Patent GB-707738-A (GB)
Title: Improvements in or relating to a heat-exchanger and method of making the same
IPC: F28D9/00
Filed: 1950-09-11
Abstract: 707,738. Heat-exchangers. SMITH, S. H. Sept. 11, 1950, No. 22299/50. Class 64(3) [Also in Group XXII] Heat-exchangers more particularly for automobile heaters and radiators are constructed by folding a flat metal sheet S to bring opposing edges together, lapping the edges to form a fluid-tight seam and bending the folded sheet or collapsed tube 10 into corrugations and inserting the tube into a mould M, Fig. 3. The tube is then inflated to acquire a shape determined by the mould, Fig. 4. Thus elongated, corrugated portions 12 are connected by short bends 13. Ports 18 are cut in outer walls 19 of the bends and a part 21 of the inner wall at each bend is directed away from the outer wall 19 so that passageways 15 are partly enlarged in cross-section, while passageways 14 are uniform in crosssection and shape. Outer walls 19 of adjacent bends are in contact so that the core tube is closed transversely at top and bottom, while the corrugations in each adjacent portion 12 touch at spaced points to form air passages 25. In Figs. 6, 7 two headers 28 having skirt portions 29 and a flange 30 at each end are soldered to the top of the core 10 and serve to collect water from and supply water to the ports 18. Water delivery or withdrawal pipes 35, 36 pass through each header and are provided with delivery ports 38. The pipes 35, 36 may be connected to the cooling system of an automobile and the air delivery line and return baffle (not shown) be attached. By using a modified mould in which the pegs are replaced by rectangular blocks with right-angled grooves at the corners, a core is produced with straight elongated portions 47 connected by right-angled bends, the inner wall of the tube at the bends being forced into a W- shaped cross-section, Fig. 9, so that tangs 52 project inwardly. Ports 55 are provided in the bends 46. The core is placed between headers 61, Fig. 11, and fins 60 are placed between the portions 47. Retaining and stiffening plates 63 cover the core ends. The fins 60 are made from sheet metal bent into serpentine form and punched out in places to form air flow deflection means. The plates 63 are flanged to grip the vertical edges of the core and are themselves held in place by flanges 67 on header plates 68. Two headers may be arranged at top and bottom of the core and the side plates may be integral with the bottom plate. In a further modification, the inner wall of the core tube is forced at the bends into a V-shaped cross-section by using mould blocks provided with slots at the corners. Instead of a continuous passageway through the core, communication between adjacent, elongated portions may be prevented by forcing the inner wall of the tube at the bend into contact with the outer wall. To produce this modification, mould blocks are used which have an upstanding rib midway between the sides of the block. Slot-like ports are made in each bend portion after inflation of the core and. the header plates have apertures registering with the slots. Fins may be inserted in the core and attached by inflating the tube with heated air to soften the solder coating and expand the tube into engagement with the fins. The solder coating the tube preferably has a lower melting point than the solder used to seal the tube. The tubular core may be bent into a "rectangular spiral" and after inflation the ends may be opened and attached to tubular headers.