JP5250210B2 - Flat tubes and heat exchangers - Google Patents

Description

  The present invention relates to a heat exchange pipe for a heat exchanger, such as a condenser for an air conditioner or a refrigerant circulation pipe for an evaporator, an oil circulation pipe for an automobile oil cooler, an engine cooling water circulation pipe for an automobile radiator, and an engine cooling water circulation pipe for a heater core. The present invention relates to a flat tube and a heat exchanger using the flat tube.

  In this specification, the term “aluminum” includes aluminum alloys in addition to pure aluminum.

  For example, as shown in FIG. 14, as a heat exchanger (70) applied to a condenser of a car air conditioner of a vehicle, a pair of aluminum headers (71) extending in the vertical direction and spaced apart in the horizontal direction are arranged. ) (72) and both headers (71) (72) are oriented in the width direction in the ventilation direction and spaced apart in the vertical direction, and both ends are connected to both headers (71) (72) It is placed between the heat exchange tubes (73) made of aluminum and the adjacent heat exchange tubes (73) and outside the heat exchange tubes (73) at both upper and lower ends and brazed to the heat exchange tubes (73). The aluminum corrugated fin (74) and the side plate (75) brazed to the corrugated fin (74) arranged outside the corrugated fin (74) at both the upper and lower ends, the left header (71), Upper and lower two header parts (7) by the partition member (76) above the central part in the height direction 1a) (71b), the right header (72) is divided into two upper and lower header parts (72a) (72b) by the partition member (76) below the center in the height direction, and the left header ( 71) A fluid inlet (not shown) is formed in the upper header portion (71a), and an inlet member (77) having a fluid inflow passage (77a) communicating with the fluid inlet is brazed to the upper header portion (71a) A fluid outlet (not shown) is formed in the lower header portion (72b) of the header (72), and an outlet member (78) having a fluid outflow passage (78a) communicating with the fluid outlet is brazed to the lower header portion (72b). Are widely used (see Patent Document 1).

  The left and right headers (71), (72) of the heat exchanger (70) described above are cylindrical pipes made of aluminum brazing sheets having brazing material layers on at least the outer surfaces, for example, aluminum brazing sheets having brazing material layers on both sides. The header body (80) is made of a brazed pipe that is molded into a piece and brazed to each other with the side edges partially overlapped, and the both ends of the header body (80) are brazed to close the openings at both ends. And an aluminum closing member (81).

  The heat exchanger pipe (73) of the heat exchanger (70) is required not only to have excellent heat exchange efficiency but also to have pressure resistance because high-pressure gas refrigerant is introduced into the heat exchanger pipe (73). Moreover, in order to reduce the size of the capacitor, it is required that the tube wall of the flat tube is thin and the tube height is low.

  What was described in patent document 1 was used as a flat tube excellent in the heat exchange efficiency used for the capacitor | condenser mentioned above. The flat tube described in Patent Document 1 spans a pair of flat walls facing each other, two side walls provided across both side edges of both flat walls, and spans both flat walls between both side walls. A plurality of reinforcing walls extending in the vertical direction and spaced apart from each other, and having a plurality of parallel fluid passages therein, the first side wall being integrated with both flat walls The second side wall is formed by a side wall forming portion that is integrally formed on the side edge of each flat wall and protrudes to the other flat wall side, and is brazed with the tips being brought into contact with each other. .

  Such a flat tube is made of a single metal plate as a whole, and has two flat wall forming portions of the same width that form both flat walls, a connecting portion that connects the flat wall forming portions and forms the first side wall. In the two flat wall forming portions, the side edges opposite to the connecting portions are integrally formed in a raised shape, and the side wall forming portion forming the second side wall and the two flat wall forming portions are integrally formed in the raised shape. A flat tube manufacturing plate-like body having a reinforcing wall forming portion is bent into a hairpin shape at a connecting portion, and the ends of both side wall forming portions are brought into contact with each other and brazed to each other, and formed on one flat wall forming portion. The tip of the reinforcing wall forming portion and the tip of the reinforcing wall forming portion formed on the other flat wall forming portion are brought into contact with each other and brazed to each other. And the thickness of the 2nd side wall formed by making two side wall formation parts face each other and brazing is thinner than the thickness of the 1st side wall which consists of a connection part.

  However, when the flat tube described in Patent Document 1 is used for the capacitor as described above, when the flying stone hits the second side wall formed of the two side wall forming portions, the second side wall may be damaged by the impact. .

  Therefore, in order to solve such a problem, the present applicant previously provided a pair of flat walls facing each other and two side walls provided across both side edges of both flat walls. The first side wall is formed integrally with the two flat walls, the second side wall is formed by combining a plurality of side wall forming portions formed integrally with the side edges of the two flat walls, and the second side wall is A first side wall forming part formed on an outer edge of the first flat wall and projecting toward the second flat wall side and having a tip abutting against the second flat wall; and an inner side of the first side wall forming part in the first flat wall A first side wall formed on the outer edge of the second flat wall, and a second side wall forming part which is formed in a portion and protrudes toward the second flat wall side and whose tip is located at an intermediate portion of the height of the second side wall. And a second side wall forming portion that protrudes to the side and a front end of which contacts the front end surface of the second side wall forming portion. A flat tube is proposed in which the tip of the wall forming part and the second flat wall, the first side wall and the second and third side wall forming parts, and the second side wall forming part and the third side wall forming part are brazed (patent) Reference 2).

  The flat tube described in Patent Document 2 is composed of a single metal plate as a whole, two flat wall forming portions, a connecting portion that integrally connects the two flat wall forming portions and forms the first side wall, and both flat surfaces. Second and third side wall forming portions provided on the side edge of the wall forming portion opposite to the connecting portion so as to protrude from the flat wall forming portion, respectively, and opposite to the connecting portion in the first flat wall forming portion Second and third sidewalls obtained by bending a flat tube manufacturing plate-like body having a first side wall forming portion extension provided by extending a side edge on the side into a hairpin shape on both sides of the connecting portion. The front end portions of the forming portion are abutted with each other, the first side wall forming portion extension portion is bent to form the first side wall forming portion, and the outer surfaces of the second and third side wall forming portions are covered by the first side wall forming portion. Creating a folded body by caulking, and The front end portion of the inner side surface of the first side wall forming portion of the bent body and the end surface of the second flat wall forming portion on the second side wall side (opposite to the connecting portion), the first side wall forming portion and the second and third side wall formation And the second side wall forming part and the third side wall forming part are simultaneously brazed. Therefore, the brazing part between the first side wall forming part and the end face on the second side wall side of the second flat wall forming part exists on one surface of the flat tube.

  By the way, the flat tube of patent document 2 is manufactured simultaneously with manufacture of the heat exchanger shown in FIG. That is, the pipe-shaped aluminum header body material having a brazing filler metal layer on at least the outer surface and having a plurality of pipe insertion holes is disposed at intervals, and the closing members are disposed at both ends of each header body material. That is, arranging a partition member in each header body material, fitting both end portions of the bent body described above when manufacturing the flat tube described in Patent Document 2 into the pipe insertion holes of both header body materials, and adjacent folding Arranging corrugated fins between the body and outside the folded body at both ends, arranging side plates outside the corrugated fins at both ends, an inlet member on one header body material, and an outlet member on the other header body material As well as arranging, heating to a predetermined temperature and manufacturing a flat tube from the bent body as described above, and simultaneously bracing other parts together By the heat exchanger is produced.

However, in the bent body described above when manufacturing Patent Document 2, the joint portion between the first side wall forming portion and the end surface of the second flat wall on the second side wall exists on the surface to which the corrugated fin is brazed. Will do. Accordingly, when the heat exchanger is manufactured, the molten brazing material melted from the header main body material flows along the joint portion and flows along the contact portion between the bent body and the corrugated fin due to a capillary phenomenon. As a result, there is a problem that the amount of brazing material covering the outer surface of the header body material must be increased, resulting in an increase in material cost and, in turn, an increase in manufacturing cost of the heat exchanger.
JP-A-6-281373 JP 2006-78163 A

  An object of the present invention is to provide a flat tube and a heat exchanger that can solve the above-described problems and can reduce the manufacturing cost when manufacturing the heat exchanger.

  In order to achieve the above object, the present invention comprises the following aspects.

1) It is provided with a pair of flat walls facing each other and two side walls provided across both side edges of both flat walls, the first side wall being formed integrally with both flat walls, The side walls of the two flat walls are formed by combining a plurality of side wall forming portions formed integrally with the side edges of the two flat walls, and the two flat wall forming portions and the two flat wall forming portions are integrally connected and the first side wall is formed. A flat tube manufacturing plate-like body provided with a connecting portion to be formed and a plurality of side wall forming portions provided on a side edge portion opposite to the connecting portion in both flat wall forming portions, and a hairpin shape at the connecting portion The second side wall is formed by brazing a plurality of side wall forming portions after the bent body is obtained by bending and bending all the side wall forming portions in combination. The outer end of the entire length only on the outer surface of the second side wall In flat tubes are exposed over,
A second side wall formed on an outer edge of the first flat wall, protruding toward the second flat wall, and having a tip abutting against the second flat wall; and a first side wall of the first flat wall A thick part formed at an interval in the inner part of the forming part and projecting to the second flat wall side and having a tip located at the middle part of the height of the second side wall, and a thickness of the tip surface of the thick part A second side wall forming portion formed of a thin wall portion integrally formed on the outer side in the direction and protruding toward the second flat wall side and having a tip abutting against the second flat wall; and a first flat wall formed on the second flat wall. And a third side wall forming portion that is fitted between the first side wall forming portion and the second side wall forming portion and whose tip is in contact with the first flat wall, and a third side wall in the second flat wall the first projecting flat wall side to the inner portion of the forming portion are formed at intervals and tip of the second side wall forming portion thickness, The fourth side wall forming portion is in contact with the inner side in the thickness direction on the front end surface of the portion, and the outer surface of the second side wall is formed by the end surface of the second side wall side edge of both flat walls and the outer surface of the first side wall forming portion. A flat tube which is formed and has an outer end portion of the brazed portion between the second flat wall and the tip of the first side wall forming portion exposed on the outer surface of the second side wall in a cross-sectional shape.

  2) The flat tube as described in 1) above, wherein the thickness of the second side wall is 1.5 to 5 times the thickness of the flat wall.

  3) The flat shape as described in 1) or 2) above, wherein in the cross-sectional shape, the brazing length of the entire side wall forming part forming the second side wall is 1.3 to 7 times the wall thickness of the second side wall. tube.

4) between a pair arranged in parallel at intervals in another header, the 1) located in parallel form a plurality of flat tubes that are described at intervals from each other in any one of 1-3) A heat exchanger in which both ends of all flat tubes are connected to both headers, fins are arranged in the ventilation gap between adjacent flat tubes, and the fins are brazed to the flat tubes.

  According to the flat tube of the above 1), since the brazing portion extending over the entire length exists only on the outer surface of the second side wall, the two flat wall forming portions and the two flat wall forming portions are integrally connected and A flat tube manufacturing plate-like body comprising a connecting portion forming one side wall and a plurality of side wall forming portions provided on a side edge portion opposite to the connecting portion in both flat wall forming portions, When a bent body is obtained by bending into a hairpin shape and further caulking all the side wall forming portions in combination, a seam portion exists only on the outer surface of the portion forming the second side wall. Therefore, when the flat tube is manufactured at the same time as the manufacture of the heat exchanger shown in FIG. 14, for example, the aluminum header body material having a brazing filler metal layer on at least the outer surface and a plurality of tube insertion holes is spaced from each other. , Disposing a closing member on each end of each header body material, disposing a partition member on each header body material, both ends of the above-described bent body when manufacturing the flat tube of 1) above Part is inserted into the pipe insertion holes of both header body materials, corrugated fins are arranged between adjacent bent bodies and outside the bent bodies at both ends, side plates are arranged outside the corrugated fins at both ends, An inlet member is placed on the header body material of the other, and an outlet member is placed on the other header body material. When the heat exchanger is manufactured by the method of brazing together other parts at the same time as the flat tube of 1) is manufactured, the molten brazing material that has melted from the header body material is caused by capillary action. The flow along the seam portion is prevented, and as a result, the flow along the contact portion between the bent body and the corrugated fin is also prevented. Accordingly, the amount of brazing material covering the outer surface of the header body material can be reduced, the material cost can be reduced, and the manufacturing cost of the heat exchanger can be reduced.

  According to the flat tube of 2) above, since the thickness of the second side wall is 1.5 to 5 times the thickness of the flat wall, even when used in a heat exchanger such as a condenser, The second side wall is prevented from being damaged due to the collision of the foreign matter, and leakage of the refrigerant is prevented.

According to the flat tube of the above 3), in the cross-sectional shape, the brazing length of the entire side wall forming part forming the second side wall is 1.3 to 7 times the wall thickness of the second side wall. The brazing strength can be improved and the corrosion resistance can be prevented from lowering due to the corrosion of the brazed portion.

When producing the heat exchanger of 4), the same effects as in 1) are obtained.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the upper and lower sides and the left and right sides of FIGS.

  In addition, the same code | symbol is attached | subjected to the same part and the same thing through all drawings, and the overlapping description is abbreviate | omitted.

Embodiment 1
This embodiment is shown in FIGS.

  1 and 2 show the flat tube of Embodiment 1, FIG. 3 shows a flat tube manufacturing plate used for manufacturing the flat tube, and FIGS. 4 to 6 show the steps of manufacturing the flat tube. Some are shown.

  In FIG. 1 and FIG. 2, the flat tube (1) is made of aluminum, and has flat upper and lower walls (2) and (3) (a pair of flat walls) facing each other and having the same thickness, and upper and lower walls (2 ) (3) The right side wall (4) (first side wall) and the left side edge of the top and bottom walls (2) (3) The left side wall (5) (second side wall) formed by combining a plurality of side wall forming parts integrally formed on the left side edge of the upper and lower walls (2) and (3), and between the side walls (4) ( 5) a plurality of reinforcing walls (6) extending over the upper and lower walls (2) (3) and spaced apart from each other and extending in the length direction, and a plurality of fluid passages arranged in parallel inside (7) Although not shown in the figure, all the reinforcing walls (6) are provided with a plurality of communication holes through which the adjacent fluid passages (7) pass so as to form a staggered arrangement as viewed from above. Yes.

  The left side wall (5) includes a first side wall forming part (8) and a second side wall forming part (9) formed integrally with the upper wall (2) (first flat wall), and a lower wall (3) (first The second side wall forming portion (10) and the fourth side wall forming portion (11) integrally formed on the (2 flat walls) are brazed in combination.

  The first side wall forming portion (8) is integrally formed on the left edge (outer edge) of the upper wall (2) (first flat wall), protrudes toward the lower wall (3) (second flat wall), and The tip is in contact with the upper surface of the lower wall (3) and brazed to the lower wall (3). The second side wall forming part (9) is integrally formed with a space on the right side part (inner part) of the first side wall forming part (8) in the upper wall (2) and protrudes toward the lower wall (3). And the thick wall part (9a) located at the middle of the height of the left side wall (5), and the lower wall integrally formed on the left side (outside in the thickness direction) of the front end surface of the thick part (9a) It consists of a thin-walled portion (9b) that protrudes to the (3) side and whose tip is in contact with the upper surface of the lower wall (3) and brazed to the lower wall (3). The third side wall forming portion (10) is formed integrally with the lower wall (3) and protrudes toward the upper wall (2), and is formed between the first side wall forming portion (8) and the second side wall forming portion (9). The first and second side wall forming portions (8), (9) and the upper wall (2) are brazed with the tip inserted between them and in contact with the upper wall (2). The fourth side wall forming portion (11) is formed integrally with the right side portion of the third side wall forming portion (10) in the lower wall (3) at an interval, protrudes toward the upper wall (2), and the tip is the first. The second side wall forming portion (9) is brazed to the second side wall forming portion (9) while being in contact with the right side (thickness direction inner side) of the front end surface of the thick portion (9a) of the thick side wall forming portion (9). And the outer surface of the left side wall (5) is formed by the left end surface (end surface of the second side wall (4) side edge) of the upper and lower walls (2) and (3) and the outer surface of the first side wall forming portion (8), A brazed portion between the lower wall (3) and the tip of the first side wall forming portion (8) exists on the outer surface of the left side wall (5).

  The reinforcing wall (6) is a reinforcing wall projection (12) (13) integrally formed in a raised shape below the upper wall (2) and a reinforcing wall integrally formed in a raised shape above the lower wall (3). The projecting ridges (14) and (15) are formed by brazing the tips with each other being abutted against each other. On the upper wall (2) and lower wall (3), two types of reinforcing wall ridges (12) (13) and (14) (15) with different thicknesses are formed alternately in the left-right direction. The thick reinforcing wall ridges (12) on the upper wall (2) and the thin reinforcing wall ridges (15) on the lower wall (3) are brazed, and the upper wall (2) The thin reinforcing wall ridge (13) and the thick reinforcing wall ridge (14) on the lower wall (3) are brazed. Hereinafter, the thick reinforcing wall projections (12) and (14) on both the upper and lower walls (2) and (3) are referred to as first reinforcement wall projections, respectively, and the thin reinforcement wall projections (13) ( 15) shall be called the second reinforcing wall projections. The first reinforcing wall projections (12) and (14) of the upper and lower walls (2) and (3) are respectively extended in the length direction thereof and the second reinforcing wall of the other wall (3) and (2). Concave grooves (16) and (17) into which the tips of the projecting ridges (15) and (13) fit are formed over the entire length. And the front-end | tip part of the 2nd reinforcement wall protruding item | line (15) of the lower wall (3) is in the recessed wall (16) of the protruding item | line (12) for the 1st reinforcement wall of the upper wall (2), and the lower wall ( In the state where the tip of the second reinforcing wall projection (13) of the upper wall (2) is press-fitted into the concave groove (17) of the first reinforcing wall projection (14) of 3), both reinforcements Wall ridges (12) (15) and (13) (14) are brazed.

  The flat tube (1) is manufactured using the flat tube manufacturing plate (20) shown in FIG.

  In FIG. 3, the flat tube manufacturing plate (20) is formed by rolling a rolling base plate made of an aluminum brazing sheet having a brazing filler metal layer on both sides, and includes upper and lower walls (2). Flat upper wall forming part (21) (flat wall forming part) and lower wall forming part (22) (flat wall forming part) having the same width and the same thickness to form (3), and upper and lower wall forming parts (21) (22) Connect the two together and connect the connecting part (23) forming the right side wall (4) and the right side edge of the upper wall forming part (21) so as to protrude straight to the right The first side wall forming portion extension (24) and the upper portion of the right side edge of the upper wall forming portion (21) are integrally formed so as to protrude upward, and the thick portion (9a) and the thin portion (9b) ) And a third side wall forming portion (10) integrally formed in an upward projecting manner on the upper surface of the left edge of the lower wall forming portion (22) with a space in the left-right direction. And second A plurality of first and second reinforcements integrally formed in a four-side wall forming portion (11), an upper wall forming portion (21), and a lower wall forming portion (22) in a raised shape at predetermined intervals in the left-right direction. Ridges (12), (13), (14), and (15) for walls, and the first ridges for reinforcing walls (12) of the upper wall forming portion (21) and the first ridges of the lower wall forming portion (22). 2 Reinforcing wall ridges (15), first reinforcing wall ridges (14) of the lower wall forming part (22) and second reinforcing wall ridges (13) of the upper wall forming part (21) , Respectively, are in positions symmetrical with respect to the center line in the left-right direction of the connecting portion (23). An aluminum brazing sheet for forming a flat tube manufacturing plate-like body (20) is, for example, an aluminum brazing material layer formed on both sides of a core material made of an Al-Mn alloy. The cladding rate of the layers is the same.

  A concave groove (16) into which the second reinforcing wall protrusion (15) of the lower wall forming part (22) is press-fitted into the front end surface of the first reinforcing wall protrusion (12) of the upper wall forming part (21). A ditch groove that is formed and the second reinforcing wall protrusion (13) of the upper wall forming portion (21) is press-fitted into the tip surface of the first reinforcing wall protrusion (14) of the lower wall forming portion (22). 17) is formed. The dimensions of the first reinforcing wall ridges (12) of the upper wall forming portion (21) and the first reinforcing wall ridges (14) of the lower wall forming portion (22), that is, the height, thickness, and groove ( The widths 16 and 17 are the same as the depths of the grooves 16 and 17. In addition, the second reinforcing wall projection (13) of the upper wall forming portion (21) and the second reinforcing wall projection (15) of the lower wall forming portion (22) have the same dimensions, that is, height and thickness. It is.

  The flat tube manufacturing plate-like body (20) is obtained by rolling a rolling base plate made of an aluminum brazing sheet provided with a brazing filler metal layer on both sides, thereby forming an upper wall forming portion (21) and a lower wall forming portion (22). , Connecting portion (23), first side wall forming portion extension (24), second to fourth side wall forming portions (9), (10), (11), and reinforcing wall ridges (12), (13) ( 14) Since (15) is integrally molded, the entire structure excluding the left end surface of the lower wall forming portion (22) and the front end surface (right end surface) of the first side wall forming portion extension (24) is brazed. Covered by a material layer.

  In the above, the plate for manufacturing a flat tube (20) is made using a rolled base plate made of an aluminum brazing sheet provided with a brazing filler metal layer on both sides, but instead of this, Al-Mn It may be made using a rolled base plate made of an aluminum brazing sheet in which a brazing filler metal layer is provided on one side of a core alloy-based core material and a sacrificial corrosion layer made of an Al-Zn alloy is provided on the other side. In this case, the connecting part (23), the second to fourth side wall forming parts (9) (10) (11), and the reinforcing wall projections (12) (13) (14) (15) Are integrally molded.

  Next, a manufacturing method of the flat tube (1) using the flat tube manufacturing plate-like body (20) will be described with reference to FIG. 4 and FIG.

  First, the flat tube manufacturing plate (20) is sequentially bent on both the left and right sides of the connecting portion (23) by roll forming (see FIG. 4 (a)), and finally is bent into a hairpin shape. The thin-walled portion (9b) of the side wall forming portion (9) is press-fitted between the third side wall forming portion (10) and the fourth side wall forming portion (11) (see FIG. 5 (a)), and the tip is lowered. It is made to contact | abut to a wall formation part (22). At the same time, the third side wall forming portion (10) is caused to run along the outer surface of the second side wall forming portion (9), and the tip thereof is brought into contact with the upper wall forming portion (21). Furthermore, the tip of the second reinforcing wall ridges (13) and (15) is press-fitted into the concave grooves (17) and (16) of the first reinforcing wall ridges (14) and (12).

  Next, the first side wall forming portion extension (24) is bent to form the first side wall forming portion (8) along the outer surface of the third side wall forming portion (10), and the tip of the first side wall forming portion is extended to the lower wall. The first side wall forming portion (8) is pressed from the outside by the first side wall forming portion (8), and the first side wall forming portion (8) (9) (10). ) And (11) are combined and caulked to obtain a bent body (20A) (see FIG. 4 (b) and FIG. 5 (b)).

  Thereafter, the bent body (20A) is heated to a predetermined temperature, and the first side wall forming part (8), the lower wall forming part (22), the third side wall forming part (10), the second side wall forming part (9) and the lower side are formed. Wall forming portion (22), second side wall forming portion (9) and third and fourth side wall forming portions (10) and (11), third side wall forming portion (10) and upper wall forming portion (21), and both The left wall (5) and the reinforcing wall (6) are brazed to each other by brazing the tips of the reinforcing wall projections (12), (15) and (13) (14) to each other using the brazing material layer. The right side wall (4) is formed by the connecting portion (23), the upper wall (2) is formed by the upper wall forming portion (21), and the lower wall (3) is formed by the lower wall forming portion (22). To do. Thus, the flat tube (1) is manufactured.

  When the flat tube (1) is used in, for example, a heat exchanger (70) applied to the condenser shown in FIG. 14, the flat tube (1) is manufactured at the same time as the heat exchanger (70). That is, the heat exchanger is manufactured as follows. First, a pair of aluminum header body materials having a plurality of bent bodies (20A), a plurality of bent body insertion holes, and at least an outer surface having a brazing material layer, a closing member (81), and a plurality of aluminum corrugated fins (74), a side plate (75), an inlet member (77), and an outlet member (78) are prepared. Next, a pair of header body materials are arranged at intervals, and closing members (81) are arranged at both ends of both header body materials. Also, the folded body (20A) and the fins (74) are alternately arranged, and both ends of the folded body (20A) are inserted into the folded body insertion holes of the header body material, and the corrugated fins (74) at both ends are outside. A side plate (75) is arranged on the side, and an inlet member (77) and an outlet member (78) are further arranged. Thereafter, these are heated to a predetermined temperature, and at the same time as manufacturing the flat tube (1) as described above, the header body (80) is manufactured from the header body material, and the header body (80) and the closing member ( 11) to produce header (71) (72), flat tube (1) and header (71) (72), flat tube (1) and corrugated fin (74), corrugated fin (74) and side plate ( 75), and the headers (71) and (72) and the inlet members (77) and (78) and the outlet member are brazed at the same time. Thus, the heat exchanger (70) is manufactured.

  A heat exchanger provided with the above-described flat tube (1) uses a refrigeration cycle and uses a refrigeration cycle having a compressor, a condenser, and an evaporator as a car air conditioner. Used as a cycle capacitor. Moreover, it is used as an evaporator of the refrigeration cycle. Furthermore, it may be mounted on an automobile as an oil cooler or radiator having the above-described flat tube (1).

The above-described flat tube (1) uses a supercritical refrigerant such as a CO ₂ refrigerant, and combines the refrigerant that has come out of the compressor, the gas cooler, the evaporator, the decompressor, and the gas cooler, and the refrigerant that has come out of the evaporator. A supercritical refrigeration cycle having an intermediate heat exchanger for heat exchange may be used for a gas cooler or an evaporator in a vehicle mounted as a car air conditioner, for example, an automobile.

Embodiment 2
This embodiment is shown in FIG. 6 and FIG.

  FIG. 6 shows the flat tube of Embodiment 2, and FIG. 7 shows a part of process of manufacturing a flat tube.

  As shown in FIG. 6, the left side wall (5) of the flat tube (30) of this embodiment includes a first side wall forming portion (31) and a second side wall forming portion (one) formed integrally with the upper wall (2). 32) and a third side wall forming portion (33) formed integrally with the lower wall (3) in combination and brazed.

  The first side wall forming portion (31) is integrally formed on the left edge of the upper wall (2), protrudes toward the lower wall (3), and the tip abuts against the upper surface of the lower wall (3) to lower the lower wall (3 ) Is brazed. The second side wall forming portion (32) is formed integrally with the right side portion of the first side wall forming portion (31) in the upper wall (2), protrudes toward the lower wall (3), and has a tip at the left side wall (5). And is brazed to the first side wall forming portion (31). The third side wall forming portion (33) is integrally formed with the lower wall (3) at the inner portion of the first side wall forming portion (31), protrudes toward the upper wall (2), and has a tip at the left side wall (5). And is brazed to the first side wall forming portion (31). Further, the end portions of the second side wall forming portion (32) and the third side wall forming portion (33) are abutted in a phased manner and brazed to each other. In other words, the tip of the second side wall forming part (32) is shaped such that the left half is cut off, and the tip of the third side wall forming part (33) is cut off of the right half. The remaining protruding portion (32a) of the second side wall forming portion (32) is fitted into the notched portion (33b) of the third side wall forming portion (33), and the third side wall forming portion is formed. The remaining projecting portions (33a) of (33) are brazed to each other in a state of being fitted in the notched portion (32b) of the second side wall forming portion (32).

  An outer surface of the left side wall (5) is formed by the left end surfaces of the upper and lower walls (2) and (3) and the outer surface of the first side wall forming portion (31), and the lower wall (3) and the first side wall forming portion (31 ) Brazed to the tip of the left side wall (5).

  Other configurations are the same as those of the flat tube (1) of the first embodiment.

  The flat tube (30) is manufactured as follows.

  The plate-like body (34) for producing the flat tube (30) is formed in the same manner as the plate-like body (20) for producing the flat tube of the first embodiment, and although not shown, Similar to the plate-like body (20) of the form 1, it has the connecting portion (23) and the reinforcing wall projections (12) (13) (14) (15). A first side wall forming portion extension (35) integrally formed so as to protrude straight outward on the side edge of the portion (21) opposite to the connecting portion (23), and an upper wall forming portion ( 21) a second side wall forming portion (32) integrally formed on the upper surface of the side edge opposite to the connecting portion (23) so as to project upward, and a connecting portion (23) of the lower wall forming portion (22) And a third side wall forming part (33) integrally formed in an upward projecting manner on the side edge on the opposite side.

  In manufacturing the flat tube (30), first, the plate-shaped body (34) for manufacturing the flat tube is sequentially bent on the left and right sides of the connecting portion (23) by a roll forming method (see FIG. 7 (a)), Finally, it is bent into a hairpin shape, and the protrusions (32a) (33a) of the second side wall forming part (32) and the third side wall forming part (33) are fitted to the notch parts (32b) (33b). The tip portions of the side wall forming portions (32) and (33) are combined in a phase-out manner. Next, the first side wall forming portion extension (35) is bent to form the first side wall forming portion (31) along the outer surfaces of the second and third side wall forming portions (32) and (33). The tip is brought into contact with the lower wall forming portion (22), and the second and third side wall forming portions (32) and (33) are pressed from the outside by the first side wall forming portion (31), and the first to first By bending the three side wall forming portions (31), (32), and (33) in combination, a bent body (34A) is obtained (see FIG. 7 (b)).

  Thereafter, the bent body (34A) is heated to a predetermined temperature, and the first side wall forming part (31) and the lower wall forming part (22), the first side wall forming part (31) and the second side wall forming part (32), and By brazing the third side wall forming portion (33) and the second side wall forming portion (32) and the tip end portions of the third side wall forming portion (33) to each other using the brazing material layer, the left side wall ( 5) is formed. In this way, a flat tube (30) is manufactured.

Embodiment 3
This embodiment is shown in FIG. 8 and FIG.

  FIG. 8 shows the flat tube of Embodiment 3, and FIG. 9 shows a part of process of manufacturing a flat tube.

  As shown in FIG. 8, the left side wall (5) of the flat tube (40) of this embodiment includes a first side wall forming portion (41) and a second side wall forming portion (one) formed integrally with the upper wall (2). 42) and a third side wall forming portion (43) and a fourth side wall forming portion (44) formed integrally with the lower wall (3) and brazed in combination.

  The first side wall forming portion (41) is formed integrally with the left edge of the upper wall (2), protrudes toward the lower wall (3), and has a tip located near the lower wall (3). The second side wall forming portion (42) is formed on the right side portion of the first side wall forming portion (41) with a space therebetween and protrudes toward the lower wall (3), and has a tip at the height of the left side wall (5). Located in the middle. The third side wall forming portion (43) is formed at the front end of the right folded portion (43a) and the right folded portion (43a) (inward folded portion) formed at the left edge of the lower wall (3). And projecting toward the upper wall (2) and being fitted between the first side wall forming part (41) and the second side wall forming part (42) and having a tip abutting against the upper wall (2) (43b) and brazed to the upper wall (2) and the first side wall forming portion (41). The fourth side wall forming portion (44) is formed on the right side portion of the third side wall forming portion (43) in the lower wall (3), protrudes toward the upper wall (2), and has a tip at the height of the left side wall (5). It is located in the middle part of the wall and is brazed to the third side wall forming part (43). Further, the tip portions of the third side wall forming part (43) and the fourth side wall forming part (44) are abutted in a phased manner and brazed to each other. That is, the tip of the second side wall forming portion (42) is shaped such that the left half is cut off, and the tip of the fourth side wall forming portion (44) is cut off of the right half. The remaining protruding portion (42a) of the second side wall forming portion (42) is fitted into the notched portion (44b) of the fourth side wall forming portion (44), and the fourth side wall forming portion is formed. The remaining protrusions (44a) of (44) are brazed to each other in a state of being fitted in the notch (42b) of the second side wall forming part (42).

  The left side wall (5) is formed by the left end surface of the upper and lower walls (2) and (3), the outer surface of the first side wall forming portion (41), and the outer surface of the right folded portion (43a) of the third side wall forming portion (43). And a brazed portion between the tip of the first side wall forming portion (41) and the right folded portion (43b) of the third side wall forming portion (43) exists on the outer surface of the left side wall (5). ing.

  The flat tube (40) is manufactured as follows.

  The plate-like body (45) for producing the flat tube (40) is formed in the same manner as the plate-like body (20) for producing the flat tube of the first embodiment, and although not shown, Similar to the plate-like body (20) of the form 1, it has the connecting portion (23) and the reinforcing wall projections (12) (13) (14) (15). A first side wall forming portion extension (46) integrally formed so as to protrude straight outward on the side edge of the portion (21) opposite to the connecting portion (23), and an upper wall forming portion ( 21) a second side wall forming part (42) integrally formed in an upward projecting manner on the upper surface of the side edge opposite to the connecting part (23), and a connecting part (23) of the lower wall forming part (22) Is formed integrally with the opposite side edge so as to protrude straight outward, and is thinner than the lower wall forming portion (22), and the lower surface is flush with the lower wall forming portion (22). The third side wall forming part extension (47) and the lower wall forming part (22) are connected to the side edge on the opposite side of the connecting part (23). And a fourth side wall forming portion (44) integrally formed in a protruding shape.

  In manufacturing the flat tube (40), first, the plate-like body (45) for manufacturing the flat tube is sequentially bent on the left and right sides of the connecting portion (23) by a roll forming method (see FIG. 9 (a)). The third side wall forming part extension (47) is bent to form the third side wall forming part (43), and finally bent into a hairpin shape to form the second side wall forming part (42) and the fourth side wall forming part ( By fitting the protruding portions (42a) and (44a) of 44) and the notched portions (42b) and (44b), the end portions of the side wall forming portions (42) and (44) are combined in a phase-out shape. Next, the first side wall forming portion extension (46) is bent to form the first side wall forming portion (41) along the outer surface of the third side wall forming portion (43), and the tip thereof is the third side. The first side wall forming portion (43) is brought into contact with the right turn portion (43a), and the third side wall forming portion (43) is pressed from the outside by the first side wall forming portion (41) to form the first to fourth side walls. By bending the parts (41), (42), (43), and (44) together, a bent body (45A) is obtained (see FIG. 9 (b)).

  Thereafter, the bent body (45A) is heated to a predetermined temperature, and the first side wall forming part (41), the third side wall forming part (43), the second side wall forming part (42), and the fourth side wall forming part (44). And the third side wall forming part (43), the upper wall forming part (21), the third side wall forming part (43), the second side wall forming part (42), and the fourth side wall forming part (44). Are brazed to each other using the brazing material layer to form the left side wall (5). In this way, a flat tube (40) is manufactured.

Embodiment 4
This embodiment is shown in FIG. 10 and FIG.

  FIG. 10 shows the flat tube of Embodiment 4, and FIG. 11 shows a part of process of manufacturing a flat tube.

  As shown in FIG. 10, the left side wall (5) of the flat tube (50) of this embodiment includes a first side wall forming part (51) and a second side wall forming part (51) integrally formed on the upper wall (2). 52) and the third side wall forming part (53) and the fourth side wall forming part (54) formed integrally with the lower wall (3) and brazed in combination.

  The first side wall forming portion (51) is formed integrally with the left edge of the upper wall (2), protrudes toward the lower wall (3), and has a tip located at the middle of the height of the left wall (5). The thick part (51a) and the thick part (51a) are integrally formed on the right side (inward in the thickness direction) of the front end surface of the thick part (51a) and project toward the lower wall (3). It consists of a thin part (51b) located on the lower wall (3) side. The second side wall forming portion (52) is formed on the right side portion of the first side wall forming portion (51) in the upper wall (2), protrudes toward the lower wall (3), and has a tip at the height of the left side wall (5). It is located in the middle part of the wall and is brazed to the first side wall forming part (51). In addition, the thickness of the part in which the 3rd side wall formation part (53) is formed in the lower wall (3) is thinner than the thickness of another part. The third side wall forming part (53) is formed on the outer edge of the lower wall (3) and protrudes toward the upper wall (2), and the tip thereof is the thick part (51a) of the first side wall forming part (51). The first side wall forming portion (51) is brazed to contact the left side (outside in the thickness direction) of the distal end surface. The fourth side wall forming portion (54) is formed on the right side of the third side wall forming portion (53) in the lower wall (3) and protrudes toward the upper wall (2), and the tip thereof is the first side wall forming portion (51). ) And the first and second side wall forming portions (51) and (52) are brought into contact with the thin wall portion (51b) and the front end surface of the second side wall forming portion (52) and brazed to the third side wall forming portion ( 53). A protrusion (52a) protruding downward is formed on the left side portion of the front end surface of the second side wall forming portion (52), and a concave groove (54a) formed on the front end surface of the fourth side wall forming portion (54). ).

  The left side wall (5) is formed by the left end face of the upper and lower walls (2) and (3), the outer surface of the thick part (51a) of the first side wall forming part (51), and the outer surface of the third side wall forming part (53). An outer surface is formed, and a brazed portion between the tip of the thick portion (51a) of the first side wall forming portion (51) and the tip of the third side wall forming portion (53) is present on the outer surface of the left side wall (5). ing.

  The flat tube (50) is manufactured as follows.

  The plate-like body (55) for producing the flat tube (50) is formed in the same manner as the plate-like body (20) for producing the flat tube of the first embodiment and is not shown in the drawings. Similar to the plate-like body (20) of the form 1, it has the connecting portion (23) and the reinforcing wall projections (12) (13) (14) (15). It is integrally formed on the side edge of the part (21) opposite to the connecting part (23) so as to protrude straight outward, and on the end face of the thick part (56a) and the thick part (56a). A first side wall forming portion extension portion (56) comprising a thin portion (56b) formed on the upper side, and an upper surface of the side edge portion on the side opposite to the connecting portion (23) of the upper wall forming portion (21) A second side wall forming portion (52) integrally formed in a projecting shape and having a ridge (52a) on the front end surface, and an outer edge on the side edge opposite to the connecting portion (23) of the lower wall forming portion (22) Is integrally formed so as to protrude straight in the direction of the wall, and is thinner than the lower wall forming portion (22). 3rd side wall forming part extension (57) which is flush with the lower wall forming part (22), and the side wall on the side opposite to the connecting part (23) of the lower wall forming part (22) And a fourth side wall forming portion (54) which is integrally formed in a protruding shape and has a concave groove (54a) on the tip surface.

  When manufacturing the flat tube (50), first, the plate-shaped body (55) for manufacturing the flat tube is bent into a hairpin shape on both the left and right sides of the connecting portion (23) by roll forming (see FIG. 11 (a)). Then, the ridge (52a) of the second side wall forming part (52) is press-fitted into the concave groove (54a) of the fourth side wall forming part (54). Next, the first side wall forming extension (56) is bent to form the first side wall forming part (51), and then the third side wall forming part extension (57) is bent to form the first side wall forming part ( The third side wall forming portion (53) is formed along the outer surface of the thin wall portion (51b) of 51), and the front end thereof is on the left side of the front end surface of the thick wall portion (51a) of the first side wall forming portion (51). And the third side wall forming portion (53) causes the thin-walled portion (51b) and the fourth side wall forming portion (54) of the first side wall forming portion (51) to be pressed from the outside, so that the first to fourth side walls are pressed. A bent body (55A) is obtained by caulking the forming portions (51), (52), (53), and (54) in combination (see FIG. 11B).

  Thereafter, the bent body (55A) is heated to a predetermined temperature, and the first side wall forming part (51), the second to fourth side wall forming parts (52) (53) (54), and the second side wall forming part (52) And the fourth sidewall forming portion (54), and the third sidewall forming portion (53) and the first and fourth sidewall forming portions (51) and (54) are brazed to each other using the brazing material layer. To form the left side wall (5). In this way, the flat tube (50) is manufactured.

Embodiment 5
This embodiment is shown in FIG. 12 and FIG.

  FIG. 12 shows the flat tube of Embodiment 5, and FIG. 13 shows a part of process of manufacturing a flat tube.

  As shown in FIG. 12, the left side wall (5) of the flat tube (60) of this embodiment includes a first side wall forming portion (61) and a second side wall forming portion (one) formed integrally with the upper wall (2). 62) and a third side wall forming part (63) and a fourth side wall forming part (64) formed integrally with the lower wall (3) and brazed in combination.

  The first side wall forming portion (61) is formed integrally with the left edge of the upper wall (2), protrudes toward the lower wall (3), and has a tip located at the middle of the height of the left wall (5). The thick wall part (61a) and the thick wall part (61a) are integrally formed on the right side (in the wall thickness direction) of the front end surface and protrude toward the lower wall (3), and the front end touches the lower wall (3). It consists of a thin part (61b) in contact. In addition, the part which the thin wall part (61b) front-end | tip of the 1st side wall formation part (61) contact | abutted in the lower wall (3) is thin compared with another part. The second side wall forming part (62) is formed on the right side of the first side wall forming part (61) on the upper wall (2), protrudes toward the lower wall (3), and has a tip at the height of the left side wall (5). The first side wall forming part (61) is brazed to the intermediate part. The third side wall forming portion (63) is formed on the outer edge of the lower wall (3) and protrudes toward the upper wall (2), and the tip is the thick wall portion (61a) of the first side wall forming portion (61). The first side wall forming portion (61) is brazed to contact the left side (outside in the thickness direction) of the front end surface. The fourth side wall forming portion (64) is formed at a right side portion of the third side wall forming portion (63) in the lower wall (3) with a gap and protrudes to the upper wall side, and the tip thereof is the second side wall forming portion ( 62) and is brazed to the first and second side wall forming portions (62). A projecting ridge (62a) projecting downward is formed at the center in the left-right direction of the tip surface of the second side wall forming part (62), It is inserted into the formed concave groove (64a).

  The left side wall (5) is formed by the left end surface of the upper and lower walls (2) and (3), the outer surface of the thick portion (61a) of the first side wall forming portion (61), and the outer surface of the third side wall forming portion (63). An outer surface is formed, and a brazed portion between the tip of the thick portion (61a) of the first side wall forming portion (61) and the tip of the third side wall forming portion (63) is present on the outer surface of the left side wall (5). ing.

  The flat tube (60) is manufactured as follows.

  The plate-like body (65) for producing the flat tube (60) is formed in the same manner as the plate-like body (20) for producing the flat tube of the first embodiment, and is not shown. Similar to the plate-like body (20) of the form 1, it has the connecting portion (23) and the reinforcing wall projections (12) (13) (14) (15). It is integrally formed on the side edge of the part (21) opposite to the connecting part (23) so as to protrude straight outward, and on the tip surface of the thick part (66a) and the thick part (66a). The first side wall forming portion extension 66 having the thin wall portion 66b formed on the upper side and the upper surface of the side wall on the side opposite to the connecting portion 23 of the upper wall forming portion 21 A second side wall forming part (62) integrally formed in a protruding shape and having a ridge (62a) on the front end surface, and an outer edge on the side edge opposite to the connecting part (23) of the lower wall forming part (22) From the portion excluding the left edge of the lower wall forming portion (22). The third side wall forming portion extension (67), which is thin and has the lower surface flush with the lower wall forming portion (22), and the connecting portion (23) of the lower wall forming portion (22) on the opposite side And a fourth side wall forming portion (64) formed integrally with the side edge portion so as to protrude upward and having a concave groove (64a) on the tip end surface.

  When manufacturing the flat tube (60), first, the plate-shaped body for manufacturing the flat tube (65) is bent into a hairpin shape on both the left and right sides of the connecting portion (23) by a roll forming method (see FIG. 13 (a)). Then, the ridges (62a) of the second side wall forming part (62) are press-fitted into the concave grooves (64a) of the fourth side wall forming part (64). Next, the first side wall forming extension portion (66) is bent to form the first side wall forming portion (61), and the tip of the thin portion (61b) is brought into contact with the lower wall forming portion (22). And along the outer side surfaces of the fourth side wall forming portions (62) and (64). Next, the third side wall forming portion extension (47) is bent to form the third side wall forming portion (63) along the outer surface of the thin portion (61b) of the first side wall forming portion (61). The tip is brought into contact with the left side of the tip surface of the thick portion (61a) of the first side wall forming portion (61), and the third side wall forming portion (63) is used to bring the first side wall forming portion (61) from the outside. By pressing and combining the first to fourth side wall forming portions (61) (62) (63) (64) and caulking, a bent body (65A) is obtained (see FIG. 13 (b)).

  Thereafter, the bent body (65A) is heated to a predetermined temperature, and the first side wall forming part (61), the second to fourth side wall forming parts (62) (63) (64), the second side wall forming part (62), By brazing the fourth side wall forming part (64) and the third side wall forming part (63) and the first side wall forming part (61) to each other using the brazing material layer, the left side wall (5) is Form. In this way, a flat tube (60) is manufactured.

  In the description of the method for manufacturing the flat tubes (30), (40), (50), and (60) in Embodiments 2 to 5, the method for forming the reinforcing wall (6) is not mentioned, but in the case of Embodiment 1 It is the same.

  Moreover, in the said Embodiments 2-5, when a flat tube (30) (40) (50) (60) is used for the heat exchanger (70) applied to the capacitor | condenser shown, for example in FIG. The manufacture of 30), 40, 50, and 60 is performed simultaneously with the manufacture of the heat exchanger 70 as in the case of the first embodiment.

It is a cross-sectional view which shows the flat tube of Embodiment 1 of this invention. It is the elements on larger scale of FIG. It is a front view which shows the flat body for flat tube manufacture used for manufacturing the flat tube shown in FIG. It is a figure which shows a part of process of manufacturing the flat tube shown in FIG. It is the elements on larger scale which show a part of process of manufacturing the flat tube shown in FIG. It is the elements on larger scale which show the flat tube of Embodiment 2 of this invention. It is the elements on larger scale which show a part of process of manufacturing the flat tube shown in FIG. It is the elements on larger scale which show the flat tube of Embodiment 3 of this invention. It is the elements on larger scale which show a part of process of manufacturing the flat tube shown in FIG. It is the elements on larger scale which show the flat tube of Embodiment 4 of this invention. It is the elements on larger scale which show a part of process of manufacturing the flat tube shown in FIG. It is the elements on larger scale which show the flat tube of Embodiment 5 of this invention. It is the elements on larger scale which show a part of process of manufacturing the flat tube shown in FIG. It is a perspective view which shows the heat exchanger applied to the capacitor | condenser for car air conditioners.

(1) (30) (40) (50) (60): Flat tube
(2): Upper wall (first flat wall)
(3): Lower wall (second flat wall)
(4): Right side wall (first side wall)
(5): Left side wall (second side wall)
(8): 1st side wall formation part
(9): Second side wall forming part
(9a): Thick part
(9b): Thin part
(10): Third side wall forming part
(11): Fourth side wall forming part
(20) (34) (45) (55) (65): Plate for flat tube manufacturing
(21): Upper wall forming part (flat wall forming part)
(22): Lower wall forming part (flat wall forming part)
(23): Connection part
(31): First side wall forming part
(32): Second side wall forming part
(33): Third side wall forming part
(41): First side wall forming part
(42): Second side wall forming part
(43): Third side wall forming part
(43a): Inward turn part
(43b): Projection
(44): Fourth side wall forming part
(51): First side wall forming part
(51a): Thick part
(51b): Thin part
(52): Second side wall forming part
(53): Third side wall forming part
(54): Fourth side wall forming part
(61): First side wall forming part
(61a): Thick part
(61b): Thin part
(62): Second side wall forming part
(63): Third side wall forming part
(64): Fourth side wall forming part

Claims (4)

A pair of flat walls facing each other and two side walls provided across both side edges of the two flat walls, the first side wall being formed integrally with the two flat walls, the second side wall Is formed by combining a plurality of side wall forming portions integrally formed on the side edge portions of both flat walls, and connects the two flat wall forming portions and the two flat wall forming portions together to form a first side wall. A flat tube manufacturing plate-like body having a connecting portion and a plurality of side wall forming portions provided on a side edge portion opposite to the connecting portion in both flat wall forming portions is bent into a hairpin shape at the connecting portion. Further, after obtaining a folded body by caulking all the side wall forming portions in combination, the second side wall is formed by brazing the plurality of side wall forming portions, and the outer side of the brazing portion in the cross-sectional shape The end is full length only on the outer surface of the second side wall In flat tubes are exposed standing,
A second side wall formed on an outer edge of the first flat wall, protruding toward the second flat wall, and having a tip abutting against the second flat wall; and a first side wall of the first flat wall A thick part formed at an interval in the inner part of the forming part and projecting to the second flat wall side and having a tip located at the middle part of the height of the second side wall, and a thickness of the tip surface of the thick part A second side wall forming portion formed of a thin wall portion integrally formed on the outer side in the direction and protruding toward the second flat wall side and having a tip abutting against the second flat wall; and a first flat wall formed on the second flat wall. And a third side wall forming portion that is fitted between the first side wall forming portion and the second side wall forming portion and whose tip is in contact with the first flat wall, and a third side wall in the second flat wall the first projecting flat wall side to the inner portion of the forming portion are formed at intervals and tip of the second side wall forming portion thickness, The fourth side wall forming portion is in contact with the inner side in the thickness direction on the front end surface of the portion, and the outer surface of the second side wall is formed by the end surface of the second side wall side edge of both flat walls and the outer surface of the first side wall forming portion. A flat tube which is formed and has an outer end portion of the brazed portion between the second flat wall and the tip of the first side wall forming portion exposed on the outer surface of the second side wall in a cross-sectional shape. The flat tube according to claim 1, wherein the thickness of the second side wall is 1.5 to 5 times the thickness of the flat wall. The flat tube according to claim 1 or 2, wherein a brazing length of all side wall forming portions forming the second side wall is 1.3 to 7 times a wall thickness of the second side wall in the cross-sectional shape. Between a pair of headers arranged parallel to each other at intervals, a plurality of flat tubes according to any one of claims 1 to 3 are arranged in parallel at intervals from each other. A heat exchanger in which both ends of a flat tube are connected to both headers, fins are arranged in a ventilation gap between adjacent flat tubes, and the fins are brazed to the flat tubes.

Images