Patent Publication Number: US-4546825-A

Title: Heat exchanger and method of assembly thereof

Description:
TECHNICAL FIELD 
     This invention relates generally to heat exchangers of the shell and tube type and, more particularly to such heat exchangers wherein the outer wall consists of two corrugated half shells welded together at their seams, the corrugations serving as seats for the headers and baffles. 
     BACKGROUND ART 
     Heretofore, heat exchanger assemblies of the shell and tube type have generally consisted of a cylindrical shell into which a tube bundle assembly of headers, baffles and tubes brazed together is inserted and brazed around the headers adjacent the ends of the cylindrical shell. 
     DISCLOSURE OF THE INVENTION 
     A general object of the invention is to provide an improved heat exchanger assembly of the shell and tube type. 
     Another object of the invention is to provide an improved and more readily assembled heat exchanger assembly wherein the outer shell consists of two welded-together half shells, each having a corrugated wall. 
     A further object of the invention is to provide a heat exchanger assembly wherein a tube assembly of headers, baffles and tubes are positioned in one corrugated half shell, with the headers and alternate baffles seated in selected corrugations, after which the other corrugated half shell is seated on the headers and remaining baffles, and the adjacent edges of the half shell welded together prior to brazing the two headers to the surrounding shell. 
     Still another object of the invention is to provide an improved method for assembling such heat exchanger assembly. 
     These and other objects and advantages of the invention will be apparent when reference is made to the following description and accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of an oil cooler heat exchanger assembly embodying the invention; 
     FIG. 2 is an end view taken along the plane of the line 2--2 of FIG. 1, and looking in the direction of the arrows; 
     FIG. 3 is a side elevational view of the inner tube assembly portion of the FIG. 1 structure; and 
     FIG. 4 is an end view taken along the plane of the line 3--3 of FIG. 2, and looking in the direction of the arrows. 
    
    
     BEST MODE OF CARRYING OUT THE INVENTION 
     Referring now to the drawings in greater detail, FIG. 1 illustrates a heat exchanger 10 of the shell and tube type, such as may be used as an oil cooler, wherein an outer shell 12 consists of two stampings serving as two symmetrical halves 14 welded together at their adjacent flanged edges 16 as seams 18 (FIG. 2). Each shell half 14 is formed to include closely spaced corrugations 20 along its full length with the exception of a predetermined short length at each end thereof. A tube bundle 22 (FIG. 3), consisting of two tube sheets or headers 24, a plurality of equally spaced, alternately positioned baffles 26, and a plurality of tubes 28 mounted through aligned openings 30 formed in the headers and baffles, is mounted in the full round shell 12 in a manner to be described. Connector means to be described are included for causing oil or other fluid to flow through the full round shell 12 intermediate the headers 24 around the tubes 28 and baffles 26, and for causing a suitable coolant, such as water to flow through the tubes 28. 
     As shown in FIGS. 1 and 3, the headers 24 are full round members, while the baffles 26 are slightly more than half round members. 
     The manufacture and assembly procedure for the heat exchanger 10 may be as follows: 
     1. Each half round shell half 14 is stamped out on a press (not shown) from flat sheet steel stock, forming the corrugations 20, along substantially the full length thereof, the flanged edges 16 and flat surfaces 32 adjacent the ends thereof, adaptable to having inlet and outlet fluid connectors 34 and 36, respectively, mounted thereon; 
     2. The perforated headers 24 and baffles 26 are inserted into respective arcuate grooves formed in a suitable assembly fixture (not shown), with alternate baffles being alternately disposed (FIG. 1); 
     3. The tubes 28 are inserted through the aligned openings 30 in the headers and baffles to complete the tube bundle 22; 
     4. A first half shell 14 is placed over the tube bundle such that the headers and baffles seat in selected corrugations 20, alternate baffles projecting outwardly therefrom; 
     5. The fixture and tube bundle are next turned over, the fixture removed, and the second half shell 14 placed thereon, such that the headers and baffles seat in selected corrugations thereof; 
     6. The assembly is thereupon placed in a suitable clamping fixture (not shown) to insure tight fitting flanged edges 16, and then welded to form the seams 18; 
     7. The tubes 28, wnich extend just beyond the respective headers 24, are brazed to the headers, and the headers are brazed to the full round shell 12, eliminating leakage from one side of the header to the other and securing the members in place as a unit; 
     8. An inlet fitting or end cap 38 is secured, as by welding, in an opening 40 formed in a circular mounting flange 42 and the latter flange, in turn, is secured, as by welding within one end of the shell 12, exterior the header 24. An outlet fitting or end cap 44 is likewise secured to another circular mounting flange 46 which is mounted within the other end of the shell 12. Hence, the inlet and outlet are in communication with each other via the intermediate open-ended tubes 28. 
     Thereafter a suitable mounting bracket 48, bearing two mounting slots 50, may be secured to the outer surface of the inlet end of the heat exchanger 10, and a second mounting bracket 52 may be secured to the outer surface of the outlet end. 
     As a variation of the above described assembly procedure, in lieu of steps 2, 4 and 5, one shell half 14 may be positioned open side up, without a holding fixture or with a simple cradle-type fixture, the headers 24 and the baffles 26 placed in the shell half, and finally the other shell half placed in position of the headers and baffles. 
     Once assembled, in operation, fluid enters through the inlet connector 34, over and around the tubes 28, but generally at right angles to the latter in view of having to contact and flow around the alternately, oppositely positioned baffles 26, and exits through the outlet connector 36, while water, or other coolant medium, flows through the tubes 28 via the inlet and outlet end caps 38 and 44, respectively. The two fluids are kept separate by the tight fit of the headers 24 in the end corrugations 20 of the full round shell 12. 
     INDUSTRIAL APPLICABILITY 
     It may be apparent from the above description that the corrugations 20: (1) add stiffness, permitting a reduction in shell wall thickness while eliminating any drawing-in of the shell during typical forming operations; (2) serve as positive spacers for the baffles, eliminating tacking or staking operations, as well as substantially reducing the possibility of the by-passing of oil therebetween which reduces cooling efficiency; and (3) reduce the gap between the shell and the headers, inasmuch as there need be no clearance provided for the insertion of a tube bundle into a cylindrical shell, as has heretofore been the case, substantially reducing the amount of brazing material required; thereby providing an efficient and more readily assembled oil cooler heat exchanger. 
     While but one apparatus embodiment and two assembly process embodiments of the invention have been shown and described, other modifications thereof are possible.