Heat exchanger, method for manufacturing the heat exchanger, and refrigeration cycle apparatus including the heat exchanger

Abstract

This heat exchanger comprises: a plurality of flat tubes that extend in the vertical direction, have a flat outer shape, and have a plurality of refrigerant flow paths formed from through holes; and a pair of headers that are connected to both ends in the vertical direction of the plurality of flat tubes, and have an L-shaped L-bent portion when viewed from above. In the heat exchanger, each of the plurality of flat tubes has a shape having a long axis and a short axis in a vertical cross-section perpendicular to a tube axis direction. Among the plurality of flat tubes, each of one or more flat tubes connected to at least the L-bent portion has a wall thickness that increases toward both ends in the long axis direction along the long axis in the vertical cross-section, and decreases toward the center in the long axis direction.

Description

Technical Field

[0001] The present disclosure relates to a heat exchanger provided with flat tubes 、Method for manufacturing this heat exchanger and a refrigeration cycle device including this heat exchanger.

Background Art

[0002] Conventionally, there has been a heat exchanger including a pair of headers facing each other with a space therebetween, and a plurality of flat tubes arranged with a space between the pair of headers and having both axial ends connected to the pair of headers (see, for example, Patent Document 1). The heat exchanger of Patent Document 1 is configured in an L shape when viewed in the direction in which the flat tubes extend, and the pair of headers have L-bent portions bent in an L shape.

[0003] The heat exchanger of Patent Document 1 discloses a technique for preventing damage to the brazed portion between the header and the flat tube at the bent portion when the pair of headers are bent in an L shape. In the heat exchanger of Patent Document 1, the outer diameter of both axial ends of the flat tube connected to the header is made larger than the outer diameter of portions other than both ends, and a large brazing allowance is secured to ensure the strength of the connection portion between the L-bent portion of the header and the flat tube and prevent damage.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The heat exchanger of Patent Document 1 has a structure in which the outer circumferences of both end portions in the tube axis direction of the flat tube are larger than the outer circumferences of portions other than the both end portions. Since the outer circumference is not uniform in the tube axis direction, the manufacturing process of the flat tube itself tends to be complicated. For this reason, it is required that the heat exchanger has a uniform outer shape of the flat tube, that is, in the tube axis direction, while increasing the strength of the connection portion. As a method of increasing the strength of the connection portion, a method of increasing the strength of the flat tube by increasing the wall thickness of the flat tube can be considered. However, in order to increase the wall thickness of the flat tube without changing the outer dimensions of the flat tube, the flow path cross-sectional area of the refrigerant flow path formed inside the flat tube has to be reduced, and there has been a problem that the pressure loss of the refrigerant increases.

[0006] The present disclosure is for solving the above-described problems, and is a heat exchanger in which a pair of headers has an L-bending portion, and is a heat exchanger capable of improving the strength of a flat tube and suppressing an increase in pressure loss. 、Method for manufacturing this heat exchanger And an object thereof is to provide a refrigeration cycle apparatus including this heat exchanger.

Means for Solving the Problems

[0007] The heat exchanger according to the present disclosure includes a plurality of flat tubes that extend in the vertical direction and are formed with an outer shape that is flat, and that have a plurality of refrigerant flow paths formed by through holes, and a pair of headers that are connected to both end portions in the vertical direction of the plurality of flat tubes and that have an L-bending portion that is L-shaped when viewed from above, and is a heat exchanger mounted on an outdoor or indoor apparatus. Each of the plurality of flat tubes has a shape having a major axis and a minor axis in a vertical cross section perpendicular to the tube axis direction. Among the plurality of flat tubes, each of at least one or two or more flat tubes connected to the L-bending portion has a larger wall thickness at both end portions in the major axis direction along the major axis in the vertical cross section, and a smaller wall thickness at the central portion in the major axis direction. In a vertical cross-section, a line passing through the center in the major axis direction is the center line, a pair of lines passing through both ends in the minor axis direction along the minor axis of a plurality of refrigerant flow paths are a pair of virtual lines at the ends of the minor axis flow paths. When a portion between a plurality of refrigerant flow paths, which is inside the pair of virtual lines at the ends of the minor axis flow paths, is called the inner column, each of one or more flat tubes has a plurality of inner columns. Among the plurality of inner columns, the thickness δ in the major axis direction of the inner column closest to the center line 1 and the thickness δ in the major axis direction of the inner column farthest from the center line among the plurality of inner columns 2 satisfy δ 2 >δ 1 . Each of one or more flat tubes has, among the plurality of inner columns, the width between the centers in the major axis direction of adjacent inner columns becoming shorter as it goes outward from the central portion in the major axis direction is such.

[0008] The method for manufacturing a heat exchanger according to the present disclosure includes a plurality of flat tubes that extend in the vertical direction, have a flat outer shape, and have a plurality of refrigerant flow paths formed by through holes, and a pair of headers that are connected to both ends in the vertical direction of the plurality of flat tubes and have an L-shaped bent portion when viewed from above. The method for manufacturing a heat exchanger is mounted on an outdoor or indoor device. Each of the plurality of flat tubes has a shape having a major axis and a minor axis in a vertical cross-section perpendicular to the tube axis direction. Among the plurality of flat tubes, each of at least one or more flat tubes connected to the L-shaped bent portion has a larger wall thickness at both ends in the major axis direction along the major axis in the vertical cross-section and a smaller wall thickness at the central portion in the major axis direction. In a vertical cross-section, a line passing through the center in the major axis direction is the center line, a pair of lines passing through both ends in the minor axis direction along the minor axis of a plurality of refrigerant flow paths are a pair of virtual lines at the ends of the minor axis flow paths. When a portion between a plurality of refrigerant flow paths, which is inside the pair of virtual lines at the ends of the minor axis flow paths, is called the inner column, each of one or more flat tubes has a plurality of inner columns. Among the plurality of inner columns, the thickness δ in the major axis direction of the inner column closest to the center line 1 and the thickness δ in the major axis direction of the inner column farthest from the center line among the plurality of inner columns 2 satisfy δ 2 >δ 1 . Each of one or more flat tubes is formed such that, among the plurality of inner columns, the width between the centers in the major axis direction of adjacent inner columns becomes shorter as it goes outward from the central portion in the major axis direction, Both ends in the tube axis direction of the plurality of flat tubes are inserted into connection ports formed in each of the pair of headers to form an integrated body, and the headers of the integrated body are bent to form L-shaped bent portions. The refrigeration cycle device according to the present disclosure includes a compressor, a condenser, an expander, and an evaporator, and at least one of the condenser and the evaporator is constituted by the above heat exchanger.

Advantages of the Invention

[0009] The heat exchanger according to the present disclosure 、Method for manufacturing this heat exchangerIn the heat exchanger and the refrigeration cycle apparatus including this heat exchanger, each of at least one or two or more flat tubes connected to the L-bending portion has a larger wall thickness at both end portions in the major axis direction along the major axis in the vertical cross section, and a smaller wall thickness at the central portion in the major axis direction. One of the both end portions in the major axis direction along the major axis in the vertical cross section is located on the outer side of the bend in the L-bending portion of the pair of headers. For this reason, in the heat exchanger and the refrigeration cycle apparatus according to the present disclosure, the wall thickness of the flat tube on the outer side of the bend in the L-bending portion of the pair of headers can be increased to increase the strength, and breakage of the flat tube can be suppressed. Further, in the heat exchanger and the refrigeration cycle apparatus according to the present disclosure, since the wall thickness of the central portion in the major axis direction of the flat tube is thinner than the wall thicknesses of both end portions in the major axis direction, the flow path cross-sectional area can be secured and an increase in pressure loss can be suppressed as compared with a configuration in which the wall thickness of the central portion in the major axis direction is made as large as the wall thicknesses of both end portions. That is, the heat exchanger can suppress an increase in pressure loss while improving the strength of the flat tube.

Brief Description of the Drawings

[0010]

Figure 1

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[0011] Hereinafter, embodiments will be described with reference to the drawings. Note that the present disclosure is not limited by the embodiments described below. Also, in the following drawings including FIG. 1, the relative dimensional relationships and shapes of each component may be different from the actual ones. Further, in the following drawings, those having the same reference numerals are the same or corresponding ones, and this shall be common throughout the entire specification. Note that the terms such as up, down, right, left, front, and back used in the following description mean the directions when the heat exchanger is viewed from the front side. These terms related to directions are described as such for convenience of explanation only, and do not limit the arrangement and orientation of the device or parts.

[0012] Embodiment 1. [Overall Configuration of Heat Exchanger 100] FIG. 1 is a schematic perspective view of a heat exchanger 100 according to Embodiment 1. The vertical direction in FIG. 1 represents the direction of gravity. The heat exchanger 100 according to Embodiment 1 is an air heat exchanger that is used as a component of a refrigeration cycle device and performs heat exchange between air and a refrigerant. In the specification, the positional relationship between each component member, the extending direction of each component member, and the parallel direction of each component member are, in principle, those when the heat exchanger 100 is installed in a usable state.

[0013] As shown in FIG. 1, the heat exchanger 100 includes a plurality of flat tubes 10 extending in the vertical direction, a pair of headers 20 disposed at both ends of the plurality of flat tubes 10 in the extending direction, and a plurality of corrugated fins 30 disposed between adjacent flat tubes 10. Note that the heat exchanger 100 is not limited to a configuration having corrugated fins 30, and may be a finless heat exchanger without corrugated fins 30, or a plate heat exchanger having a plurality of plate fins through which a plurality of flat tubes 10 pass.

[0014] The heat exchanger 100 is formed in an L shape when viewed in the vertical direction, and includes a first heat exchange portion 101 extending in the left - right direction, a second heat exchange portion 102 extending in the front - rear direction, and a third heat exchange portion 103 connecting the first heat exchange portion 101 and the second heat exchange portion 102. Each of the first heat exchange portion 101, the second heat exchange portion 102, and the third heat exchange portion 103 includes a plurality of flat tubes 10, a part of a pair of headers 20, and a plurality of corrugated fins 30.

[0015] Each of the plurality of flat tubes 10 extends in the vertical direction. The plurality of flat tubes 10 are arranged in parallel with a space therebetween. Both end portions of the plurality of flat tubes 10 in the vertical direction (tube axis direction) are inserted into a pair of headers 20 and joined by brazing.

[0016] The header 20 is a cylindrical body with both ends closed, and a space for the refrigerant to flow is formed inside. In the example of FIG. 1, the header 20 shows an example with a rectangular cross-sectional shape, but it is not limited to a rectangular shape and may be circular or elliptical, and can be changed as appropriate. In addition, the structure of the header 20 may be, for example, a laminated body of plate-like bodies with slits formed, in addition to being composed of the above-described cylindrical body with both ends closed. Further, the pair of headers 20 may have different outer shapes or cross-sectional shapes from each other.

[0017] One of the headers 20 is provided with an inlet 20a through which the refrigerant flows in, and the other header 20 is provided with an outlet 20b through which the refrigerant flows out. The refrigerant flowing into one of the headers 20 from the inlet 20a is distributed to each of the plurality of flat tubes 10 and flows from the lower end to the upper end of each flat tube 10, and then merges in the other header 20 and flows out from the outlet 20b.

[0018] Each of the pair of headers 20 is formed in an L shape when viewed in the vertical direction. The header 20 has a first straight portion 21 extending in the left-right direction, a second straight portion 22 extending in the front-rear direction, and an L-bending portion 23 connecting the first straight portion 21 and the second straight portion 22.

[0019] FIG. 2 is an explanatory diagram showing the configuration of the flat tube 10 of the heat exchanger 100 according to Embodiment 1. FIG. 3 is a schematic perspective view of the connection portion between the flat tube 10 and the header 20 of the heat exchanger 100 according to Embodiment 1. FIG. 4 is an enlarged plan view of the L-bending portion 23 of the header 20 in the heat exchanger 100 according to Embodiment 1. In FIG. 4, the outer shape of the flat tube 10 is shown by a dotted line to show the positional relationship between the header 20 and the flat tube 10. FIG. 5 is an explanatory diagram of the dimension names of the flat tube 10 of the heat exchanger 100 according to Embodiment 1. FIGS. 2 and 5 show a cross-section of the flat tube 10 perpendicular to the tube axis direction of the flat tube 10 (hereinafter referred to as a vertical cross-section).

[0020] As shown in Fig. 2, the flat tube 10 has a cross-sectional shape that is flat in one direction, such as an oval shape. The flat tube 10 has an outer shape that is configured to be flat, and has a shape with a major axis and a minor axis in a vertical cross-section. The flat tube 10 has a symmetric structure centered on the center line L1 described later.

[0021] The flat tube 10 has a pair of major axis sides 11 extending along the major axis direction along the major axis, and a pair of minor axis sides 12 extending along the minor axis direction along the minor axis. The flat tube 10 has a pair of curved portions 13 connecting both ends on one side (the left side in Fig. 2) of the pair of major axis sides 11 and both ends of the minor axis side 12a among the pair of minor axis sides 12. The flat tube 10 has a pair of curved portions 14 connecting both ends on the other side (the right side in Fig. 2) of the pair of major axis sides 11 and both ends of the minor axis side 12b among the pair of minor axis sides 12. Among the pair of minor axis sides 12, the minor axis side 12a is located on the bending outer side, and the minor axis side 12b is located on the bending inner side. Here, the bending outer side corresponds to the bending outer side of the L-bending portion 23 of the header 20 as shown in Figs. 3 and 4, and the bending inner side corresponds to the bending inner side of the L-bending portion 23 of the header 20.

[0022] The flat tube 10 is a flat porous tube having a plurality of refrigerant flow paths 10a formed by through holes. The plurality of refrigerant flow paths 10a are arranged side by side in the major axis direction. In the illustrated example, an example where the cross-sectional shape of the refrigerant flow path 10a is rectangular is shown, but it is not limited to a rectangular shape, and other shapes such as a circular shape may be used.

[0023] [Terms and dimension names for each part] First, with reference to Figs. 2, 3, and 4, the terms used in this specification will be sorted out.

[0024] R1, R2, R3, and R4 are the respective regions obtained by dividing the vertical cross-section of the flat tube 10 into four parts by the center line L1 and a pair of center virtual lines L3. The regions R1, R2, R3, and R4 are in this order, in the order from the bending outer side to the bending inner side.

[0025] Rc: The central region that is the region inside the pair of center virtual lines L3 in the vertical cross-section of the flat tube 10. Ro: The outer end region which is the region outside the pair of center virtual lines L3 in the vertical cross-section of the flat tube 10 In addition, in FIG. 4, the thin dot portion corresponds to the center region Rc, and the thick dot portion corresponds to the outer end region Ro. The center region Rc is also the region having the region R2 and the region R3. The outer end region Ro is also the region having the region R1 and the region R4.

[0026] Here L1: The center line which is the line passing through the center in the major axis direction of the flat tube 10 in the vertical cross-section of the flat tube 10 L2: A pair of outer end virtual lines which are a pair of lines passing through both ends in the major axis direction of the flat tube 10 respectively and parallel to the center line L1 in the vertical cross-section of the flat tube 10 L3: A pair of center virtual lines which are a pair of lines passing through the center between the center line L1 and each of the pair of outer end virtual lines L2 in the vertical cross-section of the flat tube 10 L4: A pair of short-axis flow path end virtual lines which are a pair of lines passing through both ends in the minor axis direction of the plurality of refrigerant flow paths 10a respectively in the vertical cross-section of the flat tube 10 L5: A pair of long-axis flow path end virtual lines which are a pair of lines passing through both ends in the major axis direction of the plurality of refrigerant flow paths 10a in the vertical cross-section of the flat tube 10

[0027] The flat tube 10 has a first outer column 15, an inner column 16, and a second outer column 17 when viewed in the vertical cross-section. The dots in FIG. 2 indicate the first outer column 15, the inner column 16, and the second outer column 17 in order from the thicker dot to the thinner dot. The definitions of the first outer column 15, the inner column 16, and the second outer column 17 are as follows.

[0028] First outer column 15: The portion which is inside the pair of short-axis flow path end virtual lines L4 and outside the pair of long-axis flow path end virtual lines L5 in the vertical cross-section Inner column 16: The portion which is inside the pair of short-axis flow path end virtual lines L4 and between adjacent refrigerant flow paths 10a in the vertical cross-section Second outer column 17: The portion which is outside the pair of short-axis flow path end virtual lines L4 in the vertical cross-section

[0029] There are two first outer columns 15 at both ends in the major axis direction. When distinguishing the first outer column 15 located on the bending outer side as the first outer column 15a and the first outer column 15 located on the bending inner side as the first outer column 15b.

[0030] Next, using FIG. 5, the dimensional names and the like at each location used in this specification are sorted out. T w : The major axis length which is the length in the major axis direction of the flat tube 10 in the vertical cross-section D p : The pitch interval of the flat tube 10 in the vertical cross-section δ1: The wall thickness in the major axis direction of the inner column 16a closest to the center line L1 among the plurality of inner columns 16 δ2: The wall thickness in the major axis direction of the inner column 16b farthest from the center line L1 among the plurality of inner columns 16 t x : The wall thickness in the major axis direction of the first outer column 15 t y : The wall thickness in the minor axis direction of the second outer column 17 Note that in the L-bending portion 23, since the pitch interval is different between the bending inner side and the bending outer side, the pitch interval D p shall be the pitch interval before bending or the pitch interval in the portion other than the L-bending portion 23.

[0031] Although it is stated that the flow path cross-section of the refrigerant flow path 10a of the flat tube 10 of the heat exchanger 100 may be circular, the dimensions in the case where the flow path cross-section of the refrigerant flow path 10a is circular are as shown in FIGS. 6 and 7 below.

[0032] FIG. 6 is a cross-sectional view showing the configuration of the flat tube 10 of the heat exchanger 100 according to Embodiment 1. FIG. 7 is an explanatory view of the dimensional names of the flat tube 10 of the heat exchanger 100 according to Embodiment 1. The dimensions in the case where the flow path cross-section of the refrigerant flow path 10a is rectangular are substantially the same as those in the circular case, and only the dimensions that require particular explanation are described here.

[0033] δ1: The wall thickness in the major axis direction of the inner column 16a closest to the center line L1 among the plurality of inner columns 16, which is the wall thickness of the narrowest part δ2: The wall thickness in the major axis direction of the inner tube 16b, which is the farthest from the center line L1 among the plurality of inner tubes 16, and is the wall thickness at the narrowest part t x : The wall thickness in the major axis direction of the first outer tube 15, and is the wall thickness at the narrowest part t y : The wall thickness in the minor axis direction of the second outer tube 17, and is the wall thickness at the narrowest part

[0034] By the way, in the heat exchanger 100, since the header 20 has the L-bending portion 23, during manufacturing, a stretching force as shown by the arrow a in FIG. 4 acts on the flat tube 10 on the outer side of the bend, and a compressing force as shown by the arrow b in FIG. 4 acts on the inner side of the bend. The directions of the arrow a and the arrow b are the minor axis directions.

[0035] FIG. 8 is a diagram showing a vertical cross-section of the flat tube 1000 in which the inner tube 160 is broken in the flat tube 1000 of the comparative example. In the flat tube 1000 of the comparative example, the left side in the drawing is the outer side of the bend, and the right side in the drawing is the inner side of the bend. In the flat tube 1000 of the comparative example, during the bending process for forming the L-bending portion, a stretching force in the direction of the arrow a (minor axis direction) acts on the outer side of the bend, causing the inner tube 160 to break and resulting in damage to the flat tube 1000. Also, from FIG. 8, it can be seen that the greater the distance from the center in the major axis direction of the flat tube 1000, in other words, the closer to both ends away from the center in the major axis direction of the flat tube 1000, the greater the deformation amount in the minor axis direction and the greater the force applied to the inner tube 160. Therefore, it can be understood that by increasing the wall thickness of the inner tube as the location approaches both ends in the major axis direction of the flat tube where a large force is applied during the bending process, while ensuring the flow path cross-sectional area, the strength of the flat tube against the L-bending portion can be improved.

[0036] Therefore, the heat exchanger 100 of Embodiment 1 can suppress damage to the flat tube 10, particularly breakage of the first outer tube 15 and the inner tube 16, by having the flat tube 10 with the following structure.

[0037] [Dimension Setting of Flat Tube 10] The flat tube 10 is formed such that the wall thickness is larger at both ends in the major axis direction in the vertical cross section and smaller at the center in the major axis direction. Specifically, as shown in FIG. 5, both ends in the major axis direction in the vertical cross section are the first outer columns 15, and the wall thickness t x of the first outer column 15 is larger than δ1 corresponding to the wall thickness at the center in the major axis direction. That is, the flat tube 10 has a relationship of t x > δ1. Note that the expression "the flat tube 10 has a larger wall thickness at both ends in the major axis direction in the vertical cross section and a smaller wall thickness at the center in the major axis direction" only requires that the wall thickness at both ends in the major axis direction in the vertical cross section is larger than the wall thickness at the center in the major axis direction, and includes a configuration in which there are the same portions among the wall thicknesses of a plurality of portions between both ends and the center in the major axis direction in the vertical cross section.

[0038] The flat tube 10 only needs to be formed such that the wall thickness is larger at both ends in the major axis direction in the vertical cross section and smaller at the center in the major axis direction. For this reason, the flat tube 10 has at least one of the following configurations (1) to (4).

[0039] (1) The flat tube 10 has a shape in which the wall thickness at both ends in the major axis direction is the largest and gradually decreases toward the center in the major axis direction. That is, the wall thickness of the first outer column 15 at both ends in the major axis direction is the largest, and the wall thickness of the inner column 16 gradually decreases toward the center in the major axis direction. (2) The flat tube 10 has a relationship of δ2 > δ1. (3) The flat tube 10 has a relationship of t x ≧ δ2 > δ1. (4) The flat tube 10 has a relationship of δ2 > δ1 > t y .

[0040] Since the flat tube 10 has the above configuration, the heat exchanger 100 can increase the wall thickness of the flat tube 10 on the bending outer side where the stretching amount in the L-shaped bending portion 23 becomes large, thereby increasing the strength and suppressing the breakage of the flat tube 10.

[0041] If the thickness of the flat tube is uniformly increased overall without changing the outer dimensions of the flat tube in the heat exchanger, while the breakage of the flat tube can be suppressed, the flow path cross-sectional area of the refrigerant flow path must be reduced. Therefore, if the heat exchanger is configured such that the thickness of the flat tube is uniformly increased overall, while the breakage of the flat tube can be suppressed, the fluid loss of the refrigerant increases, leading to performance degradation.

[0042] On the other hand, the heat exchanger 100 has the above configuration, and by increasing the thickness of the flat tube 10 on the outer side of the bend, it is possible to suppress the breakage of the flat tube 10. Since the thickness at the central part in the long axis direction remains thin, the flow path cross-sectional area can be ensured and an increase in pressure loss can be suppressed. That is, the heat exchanger 100 can suppress an increase in pressure loss while improving the strength of the flat tube 10.

[0043] Note that all of the plurality of flat tubes 10 of the heat exchanger 100 may have the above configuration, or a part of the plurality of flat tubes 10 may have the configuration. In some cases, it is sufficient if one or more flat tubes 10 connected to the L-bending portion 23 of the pair of headers 20 of the heat exchanger 100 have the above configuration. That is, in the heat exchanger 100, it is sufficient if one or more flat tubes 10 connected to the L-bending portion 23 of at least a pair of headers 20 among the plurality of flat tubes 10 have the above configuration.

[0044] [Manufacturing Method of Heat Exchanger 100] FIG. 9 is an explanatory diagram of the manufacturing process of the heat exchanger 100 according to Embodiment 1. FIG. 9 is a plan view of the heat exchanger 100, and in order to show the positional relationship between the header 20 and the flat tube 10, the outer shape of the flat tube 10 is shown by a dotted line in the header 20 portion. Note that in FIG. 9, the illustration of the refrigerant flow path 10a is omitted.

[0045] FIG. 9(a) shows an integrated unit 100A in which both end portions of a plurality of flat tubes 10 in the tube axis direction are inserted into connection ports (not shown) formed in respective ones of a pair of headers 20, and the whole is integrated by brazing in this state. When the integrated unit 100A is bent into an L shape as shown in FIG. 9(b), a heat exchanger 100 having a first heat exchange portion 101, a second heat exchange portion 102, and a third heat exchange portion 103 is manufactured.

[0046] Since the flat tubes 10 connected to at least the L-bent portion 23 of the heat exchanger 100 manufactured by the above manufacturing process have the above configuration, breakage of the flat tubes 10 can be suppressed and the heat exchanger 100 can be made highly reliable.

[0047] Note that, during manufacturing, a force that stretches in the minor axis direction acts on the outer side of the bend of the flat tube 10, and a force that compresses in the minor axis direction acts on the inner side of the bend. For this reason, in the completed product of the final heat exchanger 100, the connection portions of both end portions of the flat tube 10 in the tube axis direction with the headers 20 may not have the above configuration. For example, in the vertical cross section of the flat tube 10 at the connection portions of both end portions of the flat tube 10 in the tube axis direction of the completed product of the final heat exchanger 100 with the headers 20, the wall thicknesses at both end portions in the major axis direction may be the same as the wall thickness at the central portion in the major axis direction. However, in the completed product of the final heat exchanger 100, portions other than both end portions of the flat tube 10 in the tube axis direction have the above configuration.

[0048] [Effect of the heat exchanger 100 of Embodiment 1] The heat exchanger 100 of Embodiment 1 includes a plurality of flat tubes 10 that extend in the vertical direction and are formed with a flat outer shape, and have a plurality of refrigerant flow paths 10a formed by through holes, and a pair of headers 20 that are connected to both upper and lower end portions of the plurality of flat tubes 10 and have an L-shaped L-bent portion 23 when viewed from above. Each of the plurality of flat tubes 10 has a shape having a major axis and a minor axis in a vertical cross section perpendicular to the tube axis direction. Among the plurality of flat tubes 10, at least one or more flat tubes 10 connected to the L-bent portion 23 have a larger wall thickness at both end portions along the major axis in the vertical cross section and a smaller wall thickness at the central portion in the major axis direction.

[0049] In the heat exchanger 100 having the above-described configuration, one of both end portions in the major axis direction along the major axis in the vertical cross-section is located on the outside of the bend of the L-bending portion 23 of the pair of headers 20. For this reason, in the heat exchanger 100 having the above-described configuration, it is possible to increase the strength by increasing the wall thickness of the flat tube 10 on the outside of the bend where the amount of stretching in the L-bending portion 23 of the pair of headers 20 increases, and it is possible to suppress breakage of the flat tube 10. Further, in the heat exchanger 100 having the above-described configuration, since the wall thickness at the center portion in the major axis direction of the flat tube is thinner than the wall thicknesses at both end portions in the major axis direction, a flow path cross-sectional area can be secured as compared with a configuration in which the wall thickness at the center portion in the major axis direction is increased to be the same as the wall thicknesses at both end portions, and an increase in pressure loss can be suppressed. That is, the heat exchanger 100 can suppress an increase in pressure loss while improving the strength of the flat tube 10.

[0050] Each of one or two or more flat tubes 10 has at least one of the configurations of the above (1) to (4).

[0051] With the above-described configuration, the heat exchanger 100 can increase the strength by increasing the wall thickness of the flat tube 10 on the outside of the bend where the amount of stretching in the L-bending portion 23 of the pair of headers 20 increases, and it is possible to suppress breakage of the flat tube 10.

[0052] Embodiment 2. In the heat exchanger 100 of Embodiment 2, the configuration of the flat tube 10 is different from that of Embodiment 1. In the above Embodiment 1, the wall thickness of the flat tube 10 was specified. In Embodiment 2, the wall thickness area of the flat tube 10 is specified. Hereinafter, the description will be centered on the points in which Embodiment 2 is different from Embodiment 1, and the configurations not described in Embodiment 2 are the same as those in Embodiment 1.

[0053] FIG. 10 is a view showing a vertical cross-section of the flat tube 10 of the heat exchanger 100 according to Embodiment 2. The flat tube 10 of the heat exchanger 100 according to Embodiment 2 has at least one of the following configurations (a) to (b). (a) The flat tube 10 has a relationship of Ao > Ac. (b) The flat tube 10 has a relationship of Ao1 = Ao2 and Ao > Ac.

[0054] Here, Ao: The wall thickness area of the portion inside the pair of minor-axis flow path end virtual lines L4 in the outer end region Ro Ac: The wall thickness area of the portion inside the pair of minor-axis flow path end virtual lines L4 in the central region Rc Ao1: The wall thickness area of the region R1 Ao2: The wall thickness area of the region R4

[0055] Ac corresponds to the total wall thickness area of the portions inside the pair of minor-axis flow path end virtual lines L4 in the regions R2 and R3. Ao corresponds to the total wall thickness area of the portions inside the pair of minor-axis flow path end virtual lines L4 in the regions R1 and R4. In FIG. 10, the total area of the portions indicated by the thick dots is the wall thickness area Ao, and the total area of the portions indicated by the thin dots is the wall thickness area Ac.

[0056] The condition in (b) above is the condition that the wall thickness area Ao1 of the region R1 and the wall thickness area Ao2 of the region R4, which are two regions at both ends in the major axis direction among the four regions R1, R2, R3, and R4, are the same as each other. This condition specifies that the flat tube 10 has a shape in which the outer column 17 portion is symmetric or nearly symmetric about the center line L1, rather than a shape like a wedge, for example, in a vertical cross section.

[0057] [Effect of the heat exchanger 100 of Embodiment 2] The heat exchanger 100 of Embodiment 2 can obtain the same effects as those of Embodiment 1.

[0058] Embodiment 3. The configuration of the flat tube 10 of the heat exchanger 100 of Embodiment 3 is different from that of Embodiment 1. Embodiment 3 relates to the flow path cross-sectional area of the refrigerant flow path 10a of the flat tube 10. Hereinafter, the description will focus on the differences between Embodiment 3 and Embodiment 1, and the configurations not described in Embodiment 3 are the same as those in Embodiment 1.

[0059] FIG. 11 is a diagram showing a vertical cross-section of the flat tube 10 of the heat exchanger 100 according to Embodiment 3. As shown in FIG. 11, in the flat tube 10 of the heat exchanger 100 according to Embodiment 3, the total flow path cross-sectional area of the plurality of refrigerant flow paths 10a2 located in the outer end region Ro is smaller than the total flow path cross-sectional area of the plurality of refrigerant flow paths 10a1 located in the central region Rc. In FIG. 11, the thick dots indicate the flow path cross-sectional area of each refrigerant flow path 10a2 located in the outer end region Ro, and the thin dots indicate the flow path cross-sectional area of each refrigerant flow path 10a1 located in the central region Rc.

[0060] With the above configuration, the heat exchanger 100 according to Embodiment 3 can obtain the same effects as those of Embodiment 1.

[0061] FIG. 12 is an explanatory diagram of the uneven flow of the liquid refrigerant in the header 120. In a heat exchanger, the liquid refrigerant flowing into the header 120 may be unevenly distributed due to the influence of centrifugal force at the L-bending portion 123 and may flow excessively into the outer side of the bend of the L-bending portion 123 as shown in the portion surrounded by the dotted circle in FIG. 12. The dots in FIG. 12 indicate the liquid refrigerant staying at the L-bending portion 123.

[0062] In the heat exchanger 100 according to Embodiment 3, in the flat tube 10, the sum of the total cross-sectional areas of the refrigerant flow paths 10a2 located in the outer end region Ro is smaller than the sum of the cross-sectional areas of the refrigerant flow paths 10a1 located in the central region Rc. Therefore, in the heat exchanger 100, among the plurality of refrigerant flow paths 10a arranged in the major axis direction in the vertical cross-section of the flat tube 10, it is more difficult for the liquid refrigerant to flow into the refrigerant flow path 10a2 on the outer side of the bend than into the refrigerant flow path 10a1 at the center in the major axis direction. Thus, the heat exchanger 100 according to Embodiment 3 can suppress the excessive inflow of the liquid refrigerant into the refrigerant flow path 10a2 on the outer side of the bend.

[0063] [Effect of the heat exchanger 100 according to Embodiment 3] The heat exchanger 100 according to Embodiment 3 can obtain the same effects as those of Embodiment 1 and can suppress the excessive inflow of the liquid refrigerant into the refrigerant flow path 10a2 on the outer side of the bend in the flat tube 10.

[0064] Embodiment 4. The heat exchanger 100 of Embodiment 4 relates to the flow path cross-sectional area of the refrigerant flow path 10a of the flat tube 10, similar to the heat exchanger 100 of Embodiment 3. Hereinafter, the description will focus on the differences between Embodiment 4 and Embodiment 3, and the configurations not described in Embodiment 4 are the same as those in Embodiment 3.

[0065] FIG. 13 is a diagram showing a vertical cross-section of the flat tube 10 of the heat exchanger 100 according to Embodiment 4. The flat tube 10 of Embodiment 4 has a configuration in which the width between the centers in the major axis direction of adjacent inner columns 16 becomes shorter as it goes outward from the central portion in the major axis direction of the flat tube 10. Specifically, in FIG. 13, the flat tube 10 has a width W1 and a width W2 as the width between the centers in the major axis direction of adjacent inner columns 16, and the width W2 is shorter than the width W1.

[0066] The configuration in which the width between the centers in the major axis direction of adjacent inner columns 16 becomes shorter as it goes outward from the central portion in the major axis direction of the flat tube 10, when viewed differently, is the same as the configuration in which the length in the major axis direction of the refrigerant flow path 10a itself becomes shorter as it goes outward from the central portion in the major axis direction of the flat tube 10. In FIG. 13, the flat tube 10 has a width W1a and a width W2a as the width in the major axis direction of the refrigerant flow path 10a itself, and the width W2a is shorter than the width W1a.

[0067] [Effect of the heat exchanger 100 of Embodiment 4] The heat exchanger 100 of Embodiment 4 can obtain the same effects as those of Embodiment 3.

[0068] Embodiment 5. The configuration of the flat tube 10 of the heat exchanger 100 of Embodiment 5 is different from that of Embodiment 1. Hereinafter, the description will focus on the differences between Embodiment 5 and Embodiment 1, and the configurations not described in Embodiment 5 are the same as those in Embodiment 1.

[0069] FIG. 14 is a diagram showing a vertical cross-section of the flat tube 10 of the heat exchanger 100 according to Embodiment 5. In the flat tube 10, among the plurality of refrigerant flow paths 10a arranged in the major axis direction, the central refrigerant flow path 10a1 has a rectangular shape, and at least the end refrigerant flow paths 10a21 at both ends in the major axis direction have a rectangular shape with R provided at four corners and curved. And the flow path cross-sectional area of the end refrigerant flow path 10a21 is smaller than the flow path cross-sectional area of the other refrigerant flow paths 10a due to having R, and accordingly, the wall thickness around the end refrigerant flow path 10a21 is thicker. That is, in the flat tube 10, the periphery of the end refrigerant flow path 10a21 is thicker than the periphery of the other refrigerant flow paths 10a.

[0070] With the above configuration, the heat exchanger 100 of Embodiment 5 can increase the wall thickness at both ends in the major axis direction in the vertical cross-section of the flat tube 10, and can improve the breaking strength of the flat tube 10. In FIG. 14, among the plurality of refrigerant flow paths 10a, only the end refrigerant flow paths 10a21 at both ends in the major axis direction have a rectangular shape with R provided at four corners and curved, but it is not limited to only the end refrigerant flow paths 10a21. For example, in the heat exchanger 100, among the plurality of refrigerant flow paths 10a, the end refrigerant flow paths 10a21 at both ends in the major axis direction and the refrigerant flow paths 10a3 inside thereof may also have a rectangular shape with R provided at four corners and curved.

[0071] [Effect of the heat exchanger 100 of Embodiment 5] The heat exchanger 100 of Embodiment 5 can obtain the same effects as those of Embodiment 1.

[0072] Embodiment 6. In the heat exchanger 100 of Embodiment 6, the configuration of the flat tube 10 is different from that of Embodiment 1. Hereinafter, the description will focus on the differences between Embodiment 6 and Embodiment 1, and the configurations not described in Embodiment 6 are the same as those in Embodiment 1.

[0073] Fig. 15 is a diagram showing a vertical cross-section of the flat tube 10 of the heat exchanger 100 according to Embodiment 6. In the flat tube 10, among the plurality of refrigerant flow paths 10a arranged in the major axis direction, the refrigerant flow path 10a1 at the center is rectangular, and at least the end refrigerant flow paths 10a21 at both ends in the major axis direction have a D-shaped configuration. The D-shaped configuration means a shape having a curved portion convex to the outside in the major axis direction and a straight portion connecting both ends of the curved portion in the vertical cross-section of the flat tube 10. And, the flow path cross-sectional area of the end refrigerant flow path 10a21 is smaller than the flow path cross-sectional areas of the other refrigerant flow paths 10a due to having the D-shaped configuration, and accordingly, the wall thickness around the end refrigerant flow path 10a21 is thicker. That is, in the flat tube 10, the periphery of the end refrigerant flow path 10a21 is thicker than the periphery of the other refrigerant flow paths 10a.

[0074] With the above configuration, the heat exchanger 100 of Embodiment 6 can increase the wall thickness at both ends in the major axis direction in the vertical cross-section of the flat tube 10, and can improve the breaking strength of the flat tube 10. In Fig. 15, among the plurality of refrigerant flow paths 10a, only the end refrigerant flow paths 10a21 at both ends in the major axis direction have the D-shaped configuration, but it is not limited to only the end refrigerant flow paths 10a21. For example, in the heat exchanger 100, among the plurality of refrigerant flow paths 10a, the end refrigerant flow paths 10a21 at both ends in the major axis direction and the refrigerant flow paths 10a3 inside thereof may also have the D-shaped configuration.

[0075] [Effect of the heat exchanger 100 of Embodiment 6] The heat exchanger 100 of Embodiment 6 can obtain the same effects as those of Embodiment 1.

[0076] Embodiment 7. The heat exchanger 100 of Embodiment 7 specifies the relationship between the major axis length T w [mm] of the flat tube 10, the pitch interval D p [mm] of the flat tube 10, and the bendable radius R0 [mm] of the L-bend portion. Hereinafter, the description will focus on the differences between Embodiment 7 and Embodiment 1, and the configurations not described in Embodiment 7 are the same as those in Embodiment 1.

[0077] FIG. 16 shows the major axis length T of the flat tube 10 in the heat exchanger 100 according to Embodiment 7 w and the bendable radius R0 of the L-bend portion 23. In FIG. 16, the horizontal axis represents the major axis length T of the flat tube 10 w [mm], and the vertical axis represents the bendable radius R0 [mm] of the L-bend portion 23. FIG. 16 shows the bendable radius R0 corresponding to the major axis length T of the flat tube 10 in each case where δ2 / δ1 is 1, 2, 3, or 4 w . The bendable radius R0 is the minimum bend radius of the L-bend portion 23 that can suppress breakage of the flat tube 10

[0078] The graph of "δ2 / δ1 = 1" shows that when the flat tube 10 has the relationship of "δ2 / δ1 = 1", the bendable radius R0 is 400 [mm] when the major axis length T of the flat tube 10 is 30 [mm]. Therefore, when the flat tube 10 of the heat exchanger 100 has the relationship of "δ2 / δ1 = 1", by setting the bend radius R of the L-bend portion 23 to a value larger than the bendable radius R0 specified by the graph of "δ2 / δ1 = 1", breakage of the flat tube 10 can be suppressed. The same applies to the other graphs in FIG. 16 w Each graph in FIG. 16 is a graph obtained by substituting the value of δ2 / δ1 into the right side of the following formula (1)

[0079]

[0080]

Equation

[0081] When the flat tube 10 of the heat exchanger 100 has the relationship of 1 < δ2 / δ1, it satisfies the relationship of the above formula (1). That is, when the heat exchanger 100 sets the right side value obtained by substituting δ2 / δ1 = 1 into the right side of the above formula (1) as R1, the bend radius R of the L-bend portion 23 satisfies R > R1. Thereby, the heat exchanger 100 can suppress breakage of the flat tube 10

[0082] ​Further, when the flat tube 10 has a relationship of 2 ≦ δ2 / δ1, the heat exchanger 100 satisfies the relationship of the above formula (1). That is, when the value of R on the right side obtained by substituting δ2 / δ1 = 2 into the right side of the above formula (1) is defined as R2 for the heat exchanger 100, the bending radius R of the L-bending portion 23 satisfies R > R2. Thereby, the heat exchanger 100 can suppress the breakage of the flat tube 10.

[0083] [Effect of the heat exchanger 100 of Embodiment 7] The heat exchanger 100 of Embodiment 7 can obtain the same effects as those of Embodiment 1.

[0084] Embodiment 8. Embodiment 8 relates to a refrigeration cycle device such as an air conditioner in which the heat exchanger 100 according to any one of Embodiments 1 to 7 is mounted.

[0085] FIG. 17 is a refrigerant circuit diagram showing a schematic configuration of a refrigeration cycle device 300 according to Embodiment 8. The refrigeration cycle device 300 includes a refrigerant circuit in which a compressor 200, a suction muffler 201, a four-way switching valve 202, an outdoor heat exchanger 203, a pressure reducer 204 such as an electric expansion valve, and an indoor heat exchanger 205 are connected by pipes. The outdoor heat exchanger 203 and the indoor heat exchanger 205 function as a condenser or an evaporator by switching the four-way switching valve 202. The four-way switching valve 202 can be omitted in the refrigeration cycle device 300. Therefore, the refrigeration cycle device 300 may be configured to include a compressor 200, a condenser, a pressure reducer, and an evaporator. In an air conditioner, the indoor heat exchanger 205 is installed in an indoor device, and the remaining compressor 200, four-way switching valve 202, outdoor heat exchanger 203, and pressure reducer 204 are installed in an outdoor device.

[0086] The compressor 200 sucks in refrigerant and compresses it to a high-temperature and high-pressure state. The compressor 200 is composed of a positive displacement compressor capable of varying the operating frequency. Note that the compressor 200 is not limited to being driven with a variable operating frequency and may be a constant-speed one. The four-way switching valve 202 is connected to the discharge side of the compressor 200 and switches the flow of the refrigerant from the compressor 200.

[0087] The outdoor heat exchanger 203 is a fin-tube type heat exchanger composed of a pipe through which refrigerant flows and fins into which the pipe is inserted. The decompressor 204 expands the refrigerant. The decompressor 204 is formed of, for example, an electronic expansion valve or a thermal expansion valve capable of adjusting the opening degree, but may also be composed of a capillary tube or the like that cannot adjust the opening degree. The indoor heat exchanger 205 is a fin-tube type heat exchanger composed of a pipe through which refrigerant flows and fins into which the pipe is inserted. In the refrigeration cycle device 300, the heat exchanger 100 according to any one of Embodiments 1 to 7 is used in at least one of the outdoor heat exchanger 203 and the indoor heat exchanger 205.

[0088] In the heating operation when the refrigeration cycle device 300 is applied to an air conditioner, the four-way switching valve 202 is connected to the solid line side in FIG. 17. The high-temperature and high-pressure refrigerant compressed by the compressor 200 flows into the indoor heat exchanger 205, condenses, and liquefies. The liquefied refrigerant is decompressed by the decompressor 204 to become a low-temperature and low-pressure two-phase state, flows into the outdoor heat exchanger 203, evaporates, gasifies, and returns to the compressor 200 again through the four-way switching valve 202. That is, as shown by the solid line arrow in FIG. 17, the refrigerant circulates. By this circulation, in the outdoor heat exchanger 203 which is an evaporator, the refrigerant exchanges heat with the outside air and absorbs heat. The refrigerant that has absorbed heat is sent to the indoor heat exchanger 205 which is a condenser, exchanges heat with the indoor air, and warms the indoor air.

[0089] In the cooling operation, the four-way switching valve 202 is connected to the dashed line side in Fig. 17. When changing from the heating operation to the cooling operation, the indoor heat exchanger 205 changes from a condenser to an evaporator, and the outdoor heat exchanger 203 changes from an evaporator to a condenser. The high-temperature and high-pressure refrigerant compressed by the compressor 200 flows to the outdoor heat exchanger 203, condenses, and liquefies. The liquefied refrigerant is depressurized by the decompressor 204 and becomes a low-temperature and low-pressure two-phase state. The low-temperature and low-pressure two-phase refrigerant flows to the indoor heat exchanger 205, evaporates, gasifies, and returns to the compressor 200 again through the four-way switching valve 202. That is, as shown by the dashed arrow in Fig. 17, the refrigerant circulates. By this circulation, in the indoor heat exchanger 205 which is an evaporator, the refrigerant exchanges heat with the indoor air and absorbs heat to cool the indoor air. The refrigerant that has absorbed heat is sent to the outdoor heat exchanger 203 which is a condenser, exchanges heat with the outside air, and dissipates heat to the outside air.

[0090] Here, as the refrigerant, R407C refrigerant, R410A refrigerant, R32 refrigerant, etc. are used.

[0091] The refrigeration cycle device 300 with the above configuration includes the heat exchanger 100 according to any one of Embodiments 1 to 7, so that while improving the strength of the flat tube 10, an increase in the pressure loss of the refrigerant can be suppressed.

[0092] Note that the refrigeration cycle device 300 can be applied not only to air conditioners but also to refrigeration cycle devices used in applications such as refrigerators, freezers, vending machines, refrigeration equipment, or water heaters.

Explanation of Reference Numerals

[0093] 10 Flat tube, 10a Refrigerant flow path, 10a1 Refrigerant flow path, 10a2 Refrigerant flow path, 10a21 End refrigerant flow path, 10a3 Refrigerant flow path, 11 Long axis side, 12 Short axis side, 12a Short axis side, 12b Short axis side, 13 Bending part, 14 Bending part, 15 First outer column, 15a First outer column, 15b First outer column, 16 Inner column, 16a Inner column, 16b Inner column, 17 Second outer column, 20 Header, 20a Inlet, 20b Outlet, 21 First straight part, 22 Second straight part, 23 Part, 30 Corrugated fin, 100 Heat exchanger, 100A Integrated object, 101 First heat exchange part, 102 Second heat exchange part, 103 Third heat exchange part, 120 Header, 123 L-bending part, 160 Inner column, 200 Compressor, 201 Suction muffler, 202 Four-way switching valve, 203 Outdoor heat exchanger, 204 Expander, 205 Indoor heat exchanger, 300 Refrigeration cycle device, 1000 Flat tube, Ac Wall thickness area, Ao Wall thickness area, Ao1 Wall thickness area, Ao2 Wall thickness area, L1 Center line, L2 Outer end virtual line, L3 Center virtual line, L4 Short axis flow path end virtual line, L5 Long axis flow path end virtual line, R Bending radius, R0 Bendable radius, R1 Region, R2 Region, R3 Region, R4 Region, Rc Center region, Ro Outer end region, a Arrow, b Arrow, tx Wall thickness.

Claims

1. A heat exchanger mounted on an outdoor or indoor device, comprising: a plurality of flat tubes extending in the vertical direction and having a flat outer shape and a plurality of refrigerant flow paths formed by through holes; and a pair of headers connected to both ends in the vertical direction of the plurality of flat tubes and having an L-shaped L-bending portion when viewed from above, each of the plurality of flat tubes has a shape having a major axis and a minor axis in a vertical cross-section perpendicular to the tube axis direction, among the plurality of flat tubes, each of at least one or more flat tubes connected to the L-bending portion, the thickness is larger at both ends in the major axis direction along the major axis in the vertical cross-section, and the thickness is smaller at the central portion in the major axis direction, in the vertical cross-section, a line passing through the center in the major axis direction is a center line, a pair of lines passing through both ends in the minor axis direction along the minor axis of the plurality of refrigerant flow paths are a pair of virtual minor-axis flow path end lines, when a portion between the plurality of refrigerant flow paths, which is inside the pair of virtual minor-axis flow path end lines, is called an inner column, each of the one or more flat tubes, has a plurality of the inner columns, among the plurality of inner columns, the thickness δ1 in the major axis direction of the inner column closest to the center line and the thickness δ2 in the major axis direction of the inner column farthest from the center line among the plurality of inner columns have a relationship of δ2 > δ1, each of the one or more flat tubes, in the plurality of inner columns, a heat exchanger in which the width between the centers in the major axis direction of adjacent inner columns becomes shorter as it goes outward from the central portion in the major axis direction.

2. the one or more flat tubes, in the vertical cross-section, the heat exchanger according to claim 1, wherein the thickness is larger at both ends in the major axis direction, and the thickness gradually becomes smaller as it goes toward the central portion in the major axis direction.

3. in the vertical cross-section, a pair of lines passing through both ends in the major axis direction of the plurality of refrigerant flow paths are a pair of virtual major-axis flow path end lines, when a portion inside the pair of virtual minor-axis flow path end lines and outside the pair of virtual major-axis flow path end lines is called a first outer column, each of the one or more flat tubes, the wall thickness δ １ and the wall thickness δ ２ and the wall thickness t in the major axis direction of the first outer cylinder ｘ satisfy t ｘ ≧δ ２ >δ １ The heat exchanger according to claim 1 or claim 2, having such a relationship.

4. in the vertical cross-section, when a portion outside the pair of virtual minor-axis flow path end lines is called a second outer column, each of the one or more flat tubes, the wall thickness δ １ and the wall thickness δ ２ and the wall thickness t in the minor axis direction of the second outer column ｙ are such that δ ２ > δ １ > t ｙ The heat exchanger according to claim 1 or claim 2, having the relationship of

5. in the vertical cross-section, A line passing through the center in the major axis direction is defined as the center line, a pair of lines passing through both ends in the major axis direction and parallel to the center line are defined as a pair of outer end virtual lines, a pair of lines passing through the centers of the center line and each of the pair of outer end virtual lines are defined as a pair of center virtual lines, and a pair of lines passing through both ends in the minor axis direction along the minor axis of the plurality of refrigerant flow paths are defined as a pair of flow path end virtual lines. The vertical cross-section is When the vertical cross-section is divided into two regions, a center region inside the pair of center virtual lines and an outer end region outside the pair of center virtual lines, each of the one or more flat tubes in the outer end region, the wall thickness area Ao of the portion inside the pair of flow path end virtual lines is greater than the wall thickness area Ac of the portion inside the pair of flow path end virtual lines in the center region. The heat exchanger according to claim 1 or claim 2.

6. The vertical cross-section is When the vertical cross-section is divided into four regions by the center line and the pair of center virtual lines, each of the one or more flat tubes among the four regions, the wall thickness areas of the two regions at both ends in the major axis direction are the same. The heat exchanger according to claim 5.

7. Each of the one or more flat tubes Among the plurality of refrigerant flow paths, the total flow path cross-sectional area of the plurality of refrigerant flow paths located in the outer end region is smaller than the total flow path cross-sectional area of the plurality of refrigerant flow paths located in the center region. The heat exchanger according to claim 5.

8. Each of the one or more flat tubes Among the plurality of refrigerant flow paths, the end refrigerant flow paths at both ends in the major axis direction have a rectangular shape with R provided at four corners and are curved, and the periphery of the end refrigerant flow paths is thicker than the periphery of the other refrigerant flow paths. The heat exchanger according to claim 1 or claim 2.

9. Each of the one or more flat tubes Among the plurality of refrigerant flow paths, the end refrigerant flow paths at both ends in the major axis direction have a D-shaped shape, and the periphery of the end refrigerant flow paths is thicker than the periphery of the other refrigerant flow paths. The heat exchanger according to claim 1 or claim 2.

10. Each of the one or more flat tubes 1 < δ ２ / δ １ The heat exchanger according to claim 3, having a relationship of, and the bending radius R of the L-shaped bent portion satisfying the following formula (1). 【Number 1】 Here, T ｗ : The major axis length which is the length in the major axis direction of the flat tube in the vertical cross section, D ｐ : Pitch interval of the flat tube in the vertical cross section.

11. Each of the one or more flat tubes 2 ≤ δ ２ / δ １ having the relationship of, and the bending radius R of the L-shaped bent portion satisfying the following formula (2), the heat exchanger according to claim 3 [Number 2] Here, T ｗ : The major axis length, which is the length in the major axis direction of the flat tube in the vertical cross-section, D ｐ : Pitch interval of the flat tube in the vertical cross section. **Claim 12**: A heat exchanger mounted on an outdoor or indoor device, comprising: a plurality of flat tubes extending in the vertical direction and having a flat outer shape, the plurality of flat tubes having a plurality of refrigerant flow paths formed by through holes; and a pair of headers connected to both upper and lower ends of the plurality of flat tubes in the vertical direction and having an L-shaped L-bending portion when viewed from above. Each of the plurality of flat tubes has a shape having a major axis and a minor axis in a vertical cross-section perpendicular to the tube axis direction. Among the plurality of flat tubes, each of at least one or more flat tubes connected to the L-bending portion has a greater wall thickness at both ends in the major axis direction along the major axis in the vertical cross-section and a smaller wall thickness at the central portion in the major axis direction. Each of the one or more flat tubes is a heat exchanger in which a plurality of refrigerant flow paths are arranged in the major axis direction in the vertical cross-section, and the flow cross-sectional areas of the end refrigerant flow paths at both ends in the major axis direction among the plurality of refrigerant flow paths are smaller than the flow cross-sectional areas of the other refrigerant flow paths. **Claim 13** A refrigeration cycle device comprising a compressor, a condenser, an expander, and an evaporator. At least one of the condenser and the evaporator is configured by the heat exchanger according to Claim 1 or Claim 2. **Claim 14** A method for manufacturing a heat exchanger mounted on an outdoor or indoor device, comprising: a plurality of flat tubes extending in the vertical direction and having a flat outer shape, the plurality of flat tubes having a plurality of refrigerant flow paths formed by through holes; and a pair of headers connected to both upper and lower ends of the plurality of flat tubes in the vertical direction and having an L-shaped L-bending portion when viewed from above. Each of the plurality of flat tubes has a shape having a major axis and a minor axis in a vertical cross-section perpendicular to the tube axis direction. Among the plurality of flat tubes, each of at least one or more flat tubes connected to the L-bending portion is formed such that the wall thickness is greater at both ends in the major axis direction along the major axis in the vertical cross-section and smaller at the central portion in the major axis direction. In the vertical cross-section a line passing through the center in the major axis direction is a center line, a pair of lines passing through both ends in the minor axis direction along the minor axis of the plurality of refrigerant flow paths are a pair of virtual minor-axis flow path end lines, when a portion between the plurality of refrigerant flow paths, which is inside the pair of virtual minor-axis flow path end lines, is an inner column, each of the one or more flat tubes has a plurality of the inner columns. Among the plurality of inner columns, the wall thickness δ1 in the major axis direction of the inner column closest to the center line and the wall thickness δ2 in the major axis direction of the inner column farthest from the center line among the plurality of inner columns have a relationship of δ2 > δ1, Each of the one or more flat tubes is In the plurality of inner columns, the width between the centers in the major axis direction of adjacent inner columns is formed to be shorter as it goes outward from the central portion in the major axis direction, A method for manufacturing a heat exchanger, in which both end portions in the tube axis direction of the plurality of flat tubes are inserted into connection ports formed in respective ones of the pair of headers to form an integrated object, and the header of the integrated object is bent by bending to form the L-shaped bent portion.

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