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Flat tube for heat exchangerRelated Patent Categories: Heat Exchange, Tubular StructureFlat tube for heat exchanger description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060180299, Flat tube for heat exchanger. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to an aluminum-made flat tube for heat exchanger having one or more partitions therein, of which cross section is formed in a nearly B-like shape or the like, in particular to an aluminum-made flat tube for heat exchanger, which is formed by bending a strip-shaped metal plate coated with a brazing metal at the outer surface side thereof in the width direction and formed with slits in a top portion of the partition for allowing the brazing metal at the outer surface side to enter into the inner surface side through the slits for brazing the partition and the inner wall surface. BACKGROUND ART [0002] There is known a flat tube having a nearly B-like shape or the like in section, in which slits are intermittently formed in a top portion of a partition positioned in the central area thereof so as to allow a brazing metal at the outer surface side of the tube to enter into the inner surface side through the slits while brazing to integrally fix the top portion of the partition and the opposed inner surface of the tube by means of brazing; thereby the performance against the pressure is increased (for example, refer to FIGS. 8 and 9 in Japanese Patent Application Laid-open No. 2002-228369). [0003] When a corrosive fluid is circulated inside an aluminum-made flat tube, the inner surface side of the core metal of the flat tube is clad with a sacrificial anode material, and the outer surface side is clad with a brazing metal. In a flat tube having a nearly B-like shape in section, when a partition at the central area is formed in a manner of turn-up bending, the top portion and the inner side of the tube abutting thereon have to be brazed. In such case, the brazing metal at the outer surface side of the tube is allowed to enter into the inner surface side through slits formed in the top portion thereof. [0004] However, from experiments conducted by the inventor, the following fact was found; i.e., in the flat tubes using slits, the reliability of the brazing largely varies depending on the length of the respective slits, gaps between the slits and the like, and the workability into a tube of B-like shape in section and accuracy thereof is largely influenced thereby. [0005] Accordingly, an object of the present invention is to determine experimentally optimum conditions for the slits formed in the top portion of the partition in a flat tube having one or more partitions and formed into a B-like shape in section. DISCLOSURE OF THE INVENTION [0006] An aspect of the present invention, disclosed in claim 1, is a flat tube for heat exchanger, which includes: [0007] a pair of flat face portions (1) parallelly opposed to each other and a pair of curved portions (2) connected to both ends of the flat face portions (1) formed with a strip-shaped metal plate bent in the width direction thereof to form into a flat cylindrical shape, wherein the strip-shaped metal plate is coated with a brazing metal (3) on one surface thereof, and is bent so that the brazing metal (3) is positioned at the outer surface side of the cylindrical shape; [0008] in the central position in the width direction of one of the flat face portions (1), a turned-up portion (4) is bent up to the opposed flat surface side, and the top portion (5) of the turned-up portion (4) abuts on the inner surface of the opposed surface side to form a partition within the tube; [0009] many slits (6) for allowing the brazing metal to enter therethrough are formed intermittently being separated away from each other in the top portion (5) in the longitudinal direction thereof, [0010] wherein the length "c" of the slit (6) is 2 mm to 15 mm; the distance "e" between the edges of the neighboring slits (6) is 3 mm to 10 mm; and "e/c" is 0.6 or more. [0011] Another aspect of the present invention, disclosed in claim 2, is the flat tube for heat exchanger according to claim 1, wherein the thickness of the strip-shaped metal plate is 0.15 mm to 0.6 mm. [0012] The flat tube for heat exchanger according to the present invention has a structure as described above, and provides the following effects. [0013] The flat tube for heat exchanger according to the present invention is structured so that the top portion 5 of the turned-up portion 4, which is formed in the central portion in the width direction of the flat face portion 1, abuts on the inner surface at opposite side thereto to form a partition in the tube, wherein many slits 6 are formed intermittently being separated away from each other in the top portion 5, and the length of the slits 6 is 2 mm to 15 mm; the distance between the edges of the neighboring slits 6 is 3 mm to 10 mm; and "e/c" is 0.6 or more. Accordingly, a highly reliable flat tube for heat exchanger having a satisfactory brazing strength between the top portion 5 and the inner surface at the opposite side, which provides a high performance against the pressure and which generates no deformation nor twist while the flat tube is being formed, is provided. [0014] That is, since the length of the slits 6 is prescribed to 2 mm or more, the brazing metal reliably enters to the inner surface side through the slits 6 while brazing, the reliability on the brazing is ensured. [0015] Since the length of the slits 6 is prescribed to 15 mm or less, the working accuracy to form the turned-up portion 4 by bending the strip-shaped metal plate in the width direction thereof can be highly maintained; as a result, the reliability on the flat tube for heat exchanger can be maintained. [0016] Also, since the distance between the edges of the neighboring slits 6 is prescribed to 3 mm or more, no crack is generated between the edges of the slits 6, a highly reliable flat tube can be provided. [0017] Further, since the distance between the edges of the neighboring slits 6 is prescribed to 10 mm or less, the fillet of brazed point in the top portion 5 is formed satisfactorily while brazing, a flat tube for heat exchanger with high strength and performance against the pressure can be provided. BRIEF DESCRIPTION OF THE DRAWINGS [0018] FIG. 1 shows a cross sectional view of a flat tube for heat exchanger according to the present invention, illustrating a relevant portion of a first embodiment. [0019] FIG. 2 shows a cross sectional view illustrating the state of use of the flat tube after brazing. [0020] FIG. 3 shows a perspective view schematically illustrating a turned-up portion 4 of the flat tube. [0021] FIG. 4 shows an illustration of a strip-shaped metal plate before being shaped into the turned-up portion 4 of the flat tube. Continue reading about Flat tube for heat exchanger... Full patent description for Flat tube for heat exchanger Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Flat tube for heat exchanger patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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