MXPA97004142A - Flat tube with average strap for ac changer - Google Patents

Abstract

The reinforcing strap is formed by a fold (4) that penetrates inside the tube, the sheet band that serves to form it. The regions (7, 8) of the band adjacent to the fold form a first main wall of the tube, and the two marginal regions (13, 14) are bent 180o towards the inside of the tube with respect to the adjacent regions (11, 12), which constitute the second main wall of the tube, are joined to the fold in a watertight manner by means of welding. The external dimensions of the tube, in cross section, and the quality of the welding, do not depend on the exact width of the band. It has application to the cooling radiator of the drive motor of a motor vehicle

Description

FLAT TUBE WITH TIR NTE MEDIUM PflRfl COLOR CHANGER The invention relates to a flat tube for the circulation of a fluid in a heat exchanger, particularly a cooling radiator of the drive motor of a motor vehicle, formed by bending, following its longitudinal direction, a strip of sheet whose first face, which defines the outer surface of the tube, is coated with a welding material; said first and second tube comprising opposite principal, substantially flat and parallel, connected to each other by two complementary walls, so that a closed profile is formed; the first main wall being formed from a middle region of the same width as the band, and the second main wall from two intermediate regions, located on either side of the middle region, which are substantially juxtaposed in one same plane, and two marginal regions of the band, respectively adjacent to said intermediate regions, which are bent with respect to these towards the interior of the tube, and joined by welding to the internal face of the middle region. Said tubes are arranged in one or more rows, the tubes of the same row being aligned with each other parallel to their thickness; that is, perpendicular to its main walls. Each tube joins two fluid boxes together so as to allow the circulation of the fluid in one or more passes between the fluid boxes, thus changing the fluid heat with a flow of air that passes through the bundle of tubes and sweeps the surface outside of each tube. In a known tube of this type, the marginal regions of the band have a width corresponding to the internal thickness of the tube and are bent at right angles with respect to the intermediate regions, to be supported by their free edge on the inner face of the first main wall. Said marginal regions, whose coatings of welding material are oriented towards each other, are joined by the welding operation, to each other and to the first main wall, forming a reinforcement brace of the tube and dividing the interior thereof in two parallel conduits. , separated. It is clear that, for a tube having the structure just described, the shape and dimensions of the cross section of the tube impose the amplitude of the starting band. Therefore, it is not possible to start from the same band, unless it is cut, to obtain tubes of different dimensions. In addition, the desired width of the band must be respected with precision, which increases its manufacturing cost or implies rejections. Figure 3 partially shows a tube in which one of the marginal regions, the region 114, bent at right angles to the adjacent region 112 of the band, is normally supported on the inner face of the first main wall 107, while that the other marginal region 113, shorter, is at a distance from the wall 107. The region 113, therefore, does not participate in the reinforcement of the tube. In addition, it is difficult to guarantee the coplanarity of the adjacent region 111 with the region 112, to form the second main wall of the tube. In figure 4, region 113 has the desired length; but the region 114 is too long and is positioned obliquely with respect to the main walls 107 and 111, 112. The regions 113 and 114, therefore, are not mutually bonded and do not guarantee the desired reinforcement of the tube. There is also a lack of tightness. It is the object of the invention to remedy said drawbacks and to allow the obtaining of a tube of determined dimensions from a band whose width can vary in a certain measure, and to obtain consecutively tubes of somewhat different dimensions, from the same width of band. The invention mainly contemplates a tube of the genre defined in the introduction, and provides that the first main wall is formed by two areas of the middle region, located laterally on either side of a fold facing the inside of the tube; on which said marginal regions that are substantially folded at 180 ° are supported. The optional, complementary or alternative features of the invention are listed below. The fold is placed half the width of the first main wall of the tube. Said fold has a U-shaped cross section, the arms of which are mutually linked and extend perpendicular to said main walls; the marginal regions resting on the bottom of the U. Each marginal region is folded in U with respect to the adjacent intermediate region and is supported, by the bottom of its U, on said fold. The bottom of the U of each marginal region is in contact with that of the other marginal region and with said fold; defining these three elements, each other, an appropriate cavity to be filled with welding material when the coating present in the marginal regions is fused. Each marginal region is folded flat on the adjacent intermediate region; the marginal region and the intermediate region being in mutual contact by means of the second face of the band. The complementary walls have a curved convex profile. The complementary walls have a substantially semicircular profile. The invention also has as its purpose and method for obtaining a tube as defined above, comprising successive steps, in the course of which: a) said band is bent longitudinally to form the fold; the rest of the band extending substantially following a plane to one part and another of the fold; b) the marginal regions of the band, on the side of the mentioned plane where the fold is located, are folded back at a predetermined distance from it, in the direction of the width of the band; and c). the band is bent again at a predetermined distance on each side of the fold, to define the complementary walls of the tube; said intermediate regions pivoting substantially 180 ° to provide the marginal regions of the web in contact with the fold. The features and advantages of the invention will be set forth in greater detail in the description that follows, in which reference is made to the accompanying drawings, in which: Figure 1 is a partial cross-sectional view of a tube of according to the invention, before the welding operation. Figure 2 represents the middle part of the cross section of a tube similar to that of figure 1, formed from a band a little wider. Figures 3 and 4 are views similar to Figure 2, which refer to tubes according to the current state of the art; and Figure 5 is a partial cross-sectional view of the band used to form the tube of Figure 1, in the course of bending. Figure 1 shows, in transverse section], a flat tube 1, formed by folding the metal foil band 2, shown in figure 5. The face of the band 2 that faces downwards in figure 5, carries a lining 3 of a welding material, which covers the entire periphery of the cross section of the tube 1. 0 half the width of the band 2 is formed a fold 4 that penetrates into the interior of the tube. In cross-section, said fold has a U-shape, whose arms 5 and 6 are mutually linked and are bent at right angles with respect to the adjacent regions 7 and 8 of the band. In Figure 1, the regions 7 and 8 extend in the same plane to form a first main wall of the tube. They are joined, respectively, by regions 9 and 10, curved to the cylindrical shape, in other flat regions 11 and 12, which form the second main wall of the tube, parallel to the wall 7, 8. From + to the way, the periphery of the tube is formed by the two main faces 7, 8 and 11, 12, flat and parallel, and by two complementary curved walls 9 and 10. The marginal regions 13 and 14 of the bandadjacent to the regions 11 and 12, respectively, are bent at 180 ° with respect to those inside the tube, thus forming, with these latter regions, respective U-profiles, whose bottoms 15 and 16 are in mutual contact by means of the covering 3, and each of them in contact with the bottom 17 of the U formed by the recess 4. Between these three bottoms there is a cavity 18 with a curvilinear triangular cross section, which will be filled with welding material when the latter is melted, fll At the same time, the fusion of the welding material that covers the faces of the arms 5 and 6 facing each other, will ensure that the recess 4 remains rigid. In this way, an excelen + e maintenance of the brace formed by the fold 4 and by the marginal regions 13 and 14, and a perfect seal of the tube at the level of the bond between the three bottoms is obtained. The fact that the sealing area is adjacent to the outside of the tube facilitates, among other aspects, the operations of preparation for the welding operation (degreasing, provision of flux, stoving), as well as the control of the appearance before welding. The tube of figure 1 is strictly symmetrical with respect to the plane P passing through a part between the arms 5 and 6 and, on the other hand, between the bottoms 15 and 16. Said symmetry is broken, in the case of the tube of the 2, due to the fact that the marginal region 14 is greater than the marginal region 13, the starting band itself being slightly larger than that shown in figure 5. It is seen that said increase in width does not affect the external dimensions of the finished tube nor the relative shape and position of the three bottoms of the U 14, 16 and 17 nor, consequently, the quality of its link. Advantageously, in order to form the tube according to the invention, the fold 4 is first formed by a triple longitudinal folding of the band, then the marginal regions 13 and 14 are bent to 180 ° with respect to the adjacent regions. and 12, following the arrows Fl of figure 5. Then the regions 11 and 12 are straightened, making them pivot 180 ° with respect to the regions 7 and 8, respectively, following the arrows F2 of figure 5, rounding to form co o the regions 9 and 10 are sericilindros. The folding of the marginal regions 13 and 14 is carried out in such a way that the bottoms 15 and 16 are formed at a predetermined distance from the plane P defined by the arms 5 and ñ, thanks to which any excess or any defect in the width of the band 2 impinges on the width of the marginal regions 13 and 14 and not on the outer dimensions of the tube.

Claims (9)

NOVELTY OF THE INVENTION CLAIMS

1. - Flat tube (1) for the circulation of a fluid in a heat exchanger, particularly a cooling radiator of the driving motor of a motor vehicle, formed by bending, following its longitudinal direction, a strip of sheet (2) whose first face, which defines the outer surface of the tube, is coated with a welding material (3); the first (7, 8) and second (11, 12) tube comprising opposite, substantially flat and parallel main walls, connected to each other by means of two complementary walls (9, 10) so as to form a closed profile; the first main wall being formed by a middle region (7, 4, 8) of the width of the band and the second main wall, from two intermediate regions (11, 12) located on one side and another in the middle region , which are juxtaposed substantially in the same plane; and two marginal regions (13, 14) of the band, respectively adjacent to the intermediate regions, which are folded with respect to those, towards the interior of the tube and joined by welding on the inner face of the middle region; characterized said tube because the first main wall is formed by two zones (7, 8) of the middle region, located laterally on either side of a fold (4) bent towards the interior of the tube, on which the regions rest marginals that are substantially folded at 180 °.

2. Tube according to claim 1, characterized in that said retraction is placed half the width of the first main wall of the tube.

3. Pipe according to any of claims 1 and 2, further characterized in that the recess has a U-shaped cross section, whose arms (5, 6) are mutually linked and extend perpendicular to the main walls; the marginal regions resting on the bottom of the U.

4. Tube according to any of the preceding claims, further characterized in that each marginal region (13, 14) is folded in U with respect to the adjacent intermediate region and is supported by the bottom (15, 16) of its U, on said fold.

5. Tube according to claim 4, further characterized in that the bottom (15, 16) of the U of each marginal region is in contact with that of the other marginal region and with said recess (4); defining these three elements among themselves a cavity (18) suitable for being filled with welding material when the coating present in the marginal regions is melted.

6. Tube according to any of claims 4 and 5, further characterized in that each marginal region is folded flat on the adjacent intermediate region; the marginal region and the intermediate region being in mutual contact with the second face of the band.

7. Tube according to any of the preceding claims, further characterized in that the complementary walls (9, 10) have a curved convex profile.

8. Tube according to claim 7, characterized in that the complementary walls have a substantially semicircular profile. 9.- Procedure for obtaining a tube according to any of the preceding claims, characterized in that it comprises successive stages in the course of which: (a) said band (2) is folded longitudinally to form the fold (4); the rest of the band extending substantially following a plane to one part and another of the fold; (b) the marginal regions of the band (13, 14) are folded on the side of said plane in which the fold is located, at a predetermined distance from it, in the direction of the width of the band; and (c) the web is recurved at a predetermined distance from each side of the fold, to define the complementary walls £ 9, 10) of the tube; pivoting said intermediate regions sensibly at 180 ° to provide the marginal regions of the web in contact with the fold.