US 2488627 A
Description (OCR text may contain errors)
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ummm l man R AO EF B U T Nov.' 22, 1949 Patented Nov. 1949 TUBE AND HEADER-PLATE ASSEMBLY FOB HEAT-EXCHAN GE UNITS Donald A. Hisey, Racine, Wis., assignor to Young Radiator Company, Racine, Wis., a corporation of Wisconsin Application February 28, 1946, Serial No. 650,795
This invention relates to tube and header-l plate assemblies for heat exchange units, particularly ofthe type wherein a plurality of flat thin metal tubes, supporting a series of-closelyspaced parallel heat-dispersing 1in plates, span a pair of spaced header-plates and have their ends inserted in openings therein and subsequently solder-sealed to said plates.
In constructions of this kind, thin sheets of metal are doubled over and welded or brazed along an interlocking seam so as to form at tubes of elongated cross section the sides of which are parallel and the lateral edges of which are rounded. A battery of these tubes are inserted transversely through a series of perforated parallel sheets Iof even thinner metal, usually called finsf which serve to disperse or dissipate the heat from the fluid flowing through the tubes. Such a battery' of iinned" tubes are arranged between a pair of spaced header-plates with the tube ends inserted through openings in and solder-sealed to the header-plates.
The openings in the header-plates are stamped out. 'I'he metal thus extruded is split and turned toform a ange around the -perimeter of each opening. The practice heretofore has been to have the size and shape of the openings conform more or less exactly with the interior cross-sectional contour of the tubes. As a consequence, the exterior tube peripheries have not always fit snugly against the opening perimeters. Moreover, the flat parallel parts of the tube at times became pressed inwardly. In either 4case there was likely to be more than the desired space between the tube sides and the perimetrical portions of the openings in the tube-p1ates-and the anges therefor. Solder being used to seal the tubes to the header-plates, and solder, not having a very great tensile strength, often proved incapable of holding the two pieces of metal together as desired, when the heat exchange unit was subject to excessive strains incidentto the useof these units, especially onautomotive equip-y ment.
The main objects of this invention, therefore, are to provide an improved tube and header-platel assembly for heat exchange units wherein a tube end, when inserted into the anged header-plate opening, is forced to haveI a materially greater proportion of the external periphery of the tube in rm contact with the perimetrical surface of the flanged header-opening; and to provide an improved form of flanged opening in the header. plate which, upon the insertion of a tube into an opening will cause the sides of the tube to bow outwardly to increase the exterior peripheral contact of the tube with the perimetrical surface of the flanged header-plate opening.
A preferred embodimentof this invention is shown in the accompanying drawings, in which:
Fig. 1 is a perspective view of a section'of a heat-exchange unit embodying this invention;
Fig. 2 is an enlarged fragmentary perspective view of one end of one of the header-plates shown in Fig. .1;
Fig. 3 is a further enlarged fragment of the header-plate showing the shape and size of one of vthe flanged openings formed therein;
Fig. 4 is an end View of a tube, drawn to the same scale as the opening shown in Fig. 3;
Fig. 5 is a cross-sectional detail ofthe fragment shown in Fig. 3 with the tube end positioned preparatory to being forced into the header openins;
Fig. 6y is a plan view of the parts as shown in Fig. 5:
Fig. '7 is an enlarged cross-sectional view,- taken vertically through the tube and transversely through the header-plataon the line 'l-I of Fig. `1, showing how the solder seals the tube to the header-plate;
Fig. 8 is a transverse sectional view of the same taken on the line 8-8 of Fig. 7.
Heat-exchange units, of the type wherein this invention may be readily incorporated, comprise a plurality of tubes 8 inserted through a series of thin, perforated heat-dispersion plates 9 and -spanning the distance between a pair of spaced header-plates I0 and IIA in which have been punched a series -of openings I 3 adapted to re# ceive the ends of the tubes 8 whereby the tubes and plates maybe solder-sealed together to form a device of the general character shown in Fig. 1.
Devices of this lkind are variously used for the transferring of heat from a fluid of one temperature flowing through the tubes 8 to another fluid of a different temperaturel flowing around. the tubes in the spaces between the heat-dispersion plates 9. To that end the header-plates I0 and I i are connected to headers (not shown) which have Y conduits connected therewith to convey the uid of the one temperature to and from said headers for transmission through said tubes 8. The fluid of the other temperature is generally air forced through the spaces between the "fins and around the tubes 8.
The tubes l generally are each formed from a thin sheet metal strip doubled upon itself and soldered along an interlocking seam I2, as shown in Figs. 4 and 5. The tubes are accordingly of elongated form, as shown in the drawings, the sides being very closely if not precisely parallel, and with the lateral edges of the tube rounded, as clearly shown in Figs. 4 and 5.
Header-plates Il and Il, involving this invention, have openings I 3 punched therein. The metal extruded, in order to form the openings is slit and upset transversely of the plate to form flanges I I around the perimeters of the openings allel sides of the tubes 8. Moreover. the metal at the ends of the opening I3 is rounded as shown at I3a so as to form cam-like surfaces to the tube end.
By reason of this difference in the dimensions of the tubes 8 and the header-plate openings I3, the tubes 8 have to be forced into the openings I3. Such forcing of the tube ends into the open-A ings I3 slightly foreshortens the longitudinal cross-sectional dimension of the tube and causes the otherwise parallel sides of the tubes 8 to be bowed outwardly against the faces of the flanges I4 and the peripheral part of the openings, causing tension o'f tube wall to header opening. This materially increases the probabilities of a close contact between these peripheral surfaces, and completely obviates the necessity of opening tubes as so often has to be done with former designs. This is a very important and vital factor in such tube and header-plate assemblies, since it is necessary to seal the tubes and plates at these points of contact. The most practical sealing medium is solder. This, of course, has to be applied in a molten state.
The sealing of these joints with molten solder can be accomplished by either of two practical methods; melting a solder foil laid on the header.
plates around the tubes; or dipping the headerplates, with the tubes in place, in a solder bath.
The first of these methods involves laying a solder foil on the inside face of the header-plates before the tubes are inserted The foil is perforated to provide openingsslightly larger than but registering with the openings I3 in the header-plates. After the tubes are inserted in a foil-covered header-plate th foil is melted by means of a ame applied by a torch, as is wellknown in the manufacture of heat-exchange units of this kind. The molten solder naturally spreads over the surface of the plate, and, because of the curved perimeters of the openings I3, runs into contact with the exterior surfaces o the tubes 8. The other method involves dipping the headerplates, one at a time, in a solder bath to a depth suiiicient vto not only immerse the protruding ends of the tubes but the anges l4.\
In the first of these methods the capillarity of the opposed exterior faces of the tubes l and the flanges Il and the perimetrlcal areas of the openings I3, plus the force of gravity, will cause the molten solder to run down the tubes beyond the edges of the flanges Il. as indicated in Fig. 7. In the second of these methods the capillarity of these abutting surfaces causes the molten solder to be drawn up along the tubes to the opposite face of the header-plate. In either case the tubes :lare firmly sealed to the header-plates I 0 and It will be readily understood that the capillarity of these abutting mbe and header-plate surfaces will be increased in proportion to the reduction in space between them. Not only will the closer spacing of these peripheries enhance the capillary action on the molten solder, but it will make for a stronger union of these surfaces than is possible where the periphery of the tube is not forced so firmly into contact with the headerplate opening and flange. Therefore, there is less likelihood for the joints in this structure to become weakened or broken when the heat-exchange unit is subject to the strains of normal use, particularly on automotive equipment.
It is va general practice in producing heat-exchange units of this kind to have the tubes 8 coated with a thin film of solder prior to the tubes being inserted through the fin-plates 9. After the assembly of the fin-plates 9 on the tubes, and prior to the header-plates I0 and Il being pressed over the ends of the tubes, the assembled tubes and fin-plates are placed in an oven at a temperature of around 606 F. This causes the film of solder on the exterior surface of the tube to melt and effect a sealed union between the tubes and the perimetrical flanges around the openings in said fin-plates.
Other varitatlons and modications in the details of structure and arrangement of the parts may be resorted to within the spirit and coverage of the appended claims.
l. A tube and header plate assembly for heat exchange units comprising a plurality ofyparallel tubes of thin sheet metal of fiat elongated cross section having substantially parallel opposite walls and rounded corners interconnecting the same, a plurality of longitudinally spaced multiapertured fins disposed on and maintaining said tubes in a predetermined relationship with the tubes disposed through the apertures in the fins and a header plate having a plurality of elliptical openings therein corresponding in number and disposition to the number and disposition of said tubes with the major axes of said openings being slightly less than the major axes of said tubes and the minor axes of said openings being greater than the minor axes of said tubes, the ends of the tubes being disposed within the openings with the opposite walls adjacent thereto being bowed outwardly in substantial flush contact with the perimetrical edges of the respective openings, whereby the ends of the tubes only conform to the shape of the openings and which ends have slightly less cross sectional area. than said openings permitting said flush contact.
2. A tube and header plate assembly as defined in and by claim 1 and including means permanently bonding the fins to the tubes and the tube ends to the header plate.
3. A tube and header plate assembly as defined rinandbyelaimhin s l which the transverse eros sectional shape of the perimetrical edges of the openings in the header plate is arcuate.
4. A tube and header plate assembly for heatl 'exchange units including at least one tube of thin sheet metal of ilat elongated cross section having substantially parallel .opposite walls and rounded corners interconnecting the same, and a short header plate having at least one elliptical opening therein having a major axis slightly less than the major axis of said tube and the minor axis of said opening being greater than the minor A axisof said tube, the end of the tube being disposed within the opening with the said opposite walls adjacent thereto being bowed outwardly in l substantial flush contact with the perimetrical amm in and-by' claim 4, in which the transverse cross sectional shape of the perimetrical edge of the opening in the header plate is arcuate.
6. A tube and header plate assembly asde'ned in and by claim 4,'and including means .parmanentlyV bonding the end of the tube to the plate.' A'
-A DONALD A. HISE'Y. 3
REFERENCES crrEn The following references are of record in the ille of patent:
Y' STATES PATENTS Name i Number 4 y Dette` l 13781243 Sonneborn Sept'. 10, 1918 1,429,878'v Spery --'June`27.-1922 1,760,505l 1. .Lea .-xMay 27, 1930 1,856,618 Y Brown May`3. 1932 317,572 v Whitt et al Apr. 27, i943 C ertiicate of Correction Patent No. 2,488,627 November 22, 1949. Y'
DONALD A.4 HISEY It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:
Column 1, line 28, for the word interior read exterior;
and that the seid Letters Patent should be read With this correction therein that the same meV conform to the record of the case in the Patent OIce.
Signed and sealed this 11th day of April, A. D. 1950.
THOMAS F. MURPHY,