US1865051A - Radiator - Google Patents

Description

' June 28, 1932. R, N, TRANE 1,865,051

RADIATOR Filed Nov. 8. 1950 2 Sheets-Sheet 1 June 28, 1932T R. N. TRANE RADIA'rn Filed Nov. B. 1930 z sheets-sheet 2 @Z4/JM @a Inql" wind l? Patented June 28, 1932 I UNITED 4STATES PATENT OFFICE RADIATOR Application led November 8, 1980. Serial No. 494,258.'

My invention relates to radiators and more especially to radiators used in steam, vacuum or hot water heating systems and employing a multiplicity of fins of thin sheet metal in 5 lieat conducting relation to the heat tube portion of the radiator, which contains the heating medium. Iii heating a room such a radiator, as compared with Vthe usual cast iron radiator, operates more upon the principle io of conduction of air than upon the principle of radiation.

One of the objects of my invention is to provide an improved heat conducting contact between the fins and the heat tube Whereby very thin sheet metal may be used for the fins and the heat tube ma y be of relativelysmall diameter, and still there will be sufficient heat conduction from the tube onto .the

body of the fin to conduct the heat at the required rate. My solution for this problem involves the feeding of a substantial quantity of heat from each heat-tube-engaging flange portion of a fin not only to the radiating plate portion of its associated fin but also to the radiating plate portion of the adjacent fin in such a manner as to circumvent the restrictive or bottlemecking eiect usually encountered at the corner formed by the cylindrical heat-tube-engaging portion and the u radiating plate portion of the conventional iin.

Another object is a construction and a method of making a radiator wherein the cost of material is minimized in proportion to the 3.', Capacity of the radiator and Where the manufacturing operations are greatly simplified.

Another object of my invention is the provision of a radiator which, for the same heatinv capacity, has a volume, floor area, Weight,

4o height and cost considerably less than the usual cast iron radiator construction. As coinpa-red with the usual design of cast iron radiators, my radiator unit described in this specification, for example, has but 60% of the manufacturing cost, 8% or 10% of the weight, and less floor space.

Another object of my invention is the prolvision of a radiator which employs fins made from very thin sheet metal, but which are so 5o designed that they are sufficiently strong and have a. maximum area available for heat radiation. l

Another object is to increase the speed of the air circulating through the radiator unit, which is accomplished by the correct design I6 of the radiator unit.

Another object is the provision of an improved radiator assembly with the parts so formed and arranged that the fins may be stacked and will withstand considerable axial 'pressure during assembly without danger of telescoping, jamming, creeping or improper spacing of the fins.

Another object is the provision of improved fins which will facilitate the assembly of the same on heat tubes in the construction of radiators and which result in a radiator having greater radiating capacity than radiators heretofore constructed.

This application is in part a continuation of my application Serial No. 282,000, filed May 31, 1928 which isa division of my pending application, Serial No. 104,196', filed April 23, 1926, which has matured into Patent No. 1,805,116, issued May 21, 1931.

In the accompanying drawings,

Fig. 1 is a perspective view of a preferred form of my radiator unit;

Fig. 2 is a vertical transverse section through the unit which may be considered as taken along the line 2-2 of Fig. 3;

Fig. 3 is a fragmentary sectional View of a heat tube having spaced flanged ins mounted thereon with the heat conducting contact effected by the melting of solder rings surrounding the flanges of the fins; o

Fig. 4 shows an alternative method consisting of holding the ianges of the fins directly to the heat tube; w

Fig. 5 is a fragmentary section of a heat tube with fins mounted thereon in heat conducting contact therewith and frictionally `held in place without the use of solder rings which in this modification have been elimi. 95 nated;

Fig. 6 is a fragmentary section similar to Figure 5 but showing a slightly modified lform of fin to form a inore eiicient heat conducting engagement between the adjacent fins and between the spacing flange and the heat tube;

Fig. 7 is a. much enlarged fragment of that shown in Fig. 6;

Fig. 8 is a top plan view of a single fin of the type shown in Fig. (i and showing two heat tubes in dotted outline; and

Fig. 9 is a diagrammatic fragmentary sccfion somewhat like Fig. 7, but showing the lconventional flanged fin of the prior art for thepurpose of illustrating the bottle necking and the one way heat conduction from the flange to only one fin; and

Fig. 10 is a similar diagram illustrating the two way heat conduction from the flange tto two different fins as achieved by my invention.

In Figs. 1 and 2 the radiator unit as shown employs a pair of spaced tubes 10 conveniently formed by bending a single tube into a U-shape. A multiplicity of closely spaced fins 11 formed from very thin sheet metal are threaded upon the spaced tubes, making contact therewith by the. aid of flanges 12 drawn out from the sheet stock of the fins about the margins of spaced openings through which the respective tubes pass.

In order to keep the radiator as light as possible, I prefer to use very thin metal for the fins. Sheet copper .006 inch thick has been found to give very satisfactory results and a minimum weight. The flanges 12 drawn from such thin sheets if drawn flat as arc flanges 13 in Fig. 4, would not have enough strength to form and maintain a goed heat conducting contact with the outer surface of a tube 10, and the flanges would not be thick enough to serve as spacers between adjacent fins without danger of the flanges overlapping or being crimped.

In the embodiment of the present application I obtain the advantages of heat conducting contact of the flanges with the tubes and this embodiment offers the further advantage of not necessitating a spacing sleeve. Also in this embodiment the entire operation may be performed on the unit simultaneously as is shown in Fig. 3. Here the fins 11 are provided with annular quarter round grooves 14 at the point where they are joined by the flanges 12. The fins are assembled on the tube 10 with the flanges 12 fitting relatively snugly on the tubes but with a ring of solder 15 lying in each groove 14. The outer edge of each flange 12 is preferably provided with an outwardly bent sub-flange 16, whereby the flanges act as spacers for the fins preventing telescoping of the flanges 12. The sub-flange 16 by its contact with the adjacent fin unit offers a further conduction from the tube engaging flange 12, thereby in! creasing the radiating capacity of the radiator as a whole.

When thus assembled the radiator unit is placed on its end with the tubes extending vertically and the flanges 12 pointing downwardly. A blow torch 17 is then pushed upwardly through each tube slowly enough to insure the complete melting of the solder iu the ring 15 and allowing the solder to find its way into any minute creviecs between the flanges 12 and the tube. When the. flame is withdrawn and the radiator cools, there is a complete metallic lieat conducting contact between the entire area ol' each flange and the periphery of the tube 10.

IVhile l have shown a flame as a heating ineens, it is understood that this is only diagrammatic and that any suitable heating means may be, used for this purpose. A method of' heating electrically is shown in Fig. 4, which illustrates a method of welding the flanges 13 of the fins 11 directly to the tube T. Here electrodes 1S and 19 within and without the tube weld the flanges to the tube as indicated at. 2l. It is obviousl that the surfaces of the flange and the tube may be tinned or coated with a suitable solder and that this heating means may, if desired, be applied to melt the solder in thc embodiment shown in Fig. 3.

In Fig. 5 the fins 11 are provided with spacing flanges 12 and outwardly turned sub-flanges 16 as in Fig. 3 but the recesses at the junction of the body of the fins and theirl spacing flanges are omitted, permitting the sub-flanges to directly engage the body of the adjacent fin to insure accurate spacing of'the. fins on the heat tube and to provide for the conduction of heat to two fins from each heat tube engaging flange 12. The necessity of using solder with this specific form of fin is obviated by slightly expanding the tubes 10 to increase the frictional engagement of the spacing flanges with the .tubes and thereby insure firm heat conducting contact.

In Figs. 6, 7 and 8 the fins 11 are provided with ,the spacing flanges 12 and the outwardly turned reinforcing flanges 22, similar to the flanges 16 in Fig. 5, but the flanges 22 do not extend as nearly at right angles to the spacing flanges as th'e flanges 16 do in Fig. 5.

In Fig. 7 the construction is more specifically illustrated. The flange 22 is turned or flared outwardly very accurately, to abut directly on its end at 23 with the body of the fin 11 at the point of curvature where it joins l the spacing flange. In the formation of the flange 22 it is slightly thinned toward the end. The end face at the point 23 is not perpendicular to the line 24 representing the direction of the flange 22 extended. Instead it lies .on a line 25 tangent to the junction of the'fn and its flange 12 at substantially the point 23 and more specifically the line of eX- tension 24 passes outwardly of the point 26 which is the center of curvature of the arcuate junction portion and forms an angle X- preferably between 10 degrees and 430 degrecs-with the line 27 which passes through the point 26 and is normal to t e tangent line 25 at the point 23. As the angle X approaches zero or as theline 24 passes below the normal line 27. the likelihood of the flange 22 becoming jammed beneath the adjacent flange 12 increases. On the other hand as the angle X approaches or increases beyond 30 degrees. the danger of buckling up of the flange 22 increases. Such buckling would not only impair the uniformity of spacing but would reduce the area of heat conducting contact of the end of the flange 22 with the adjacent fin. A further and very `important objection to such coupling is the reduction of the pressure on the area of contact and the reduction of the total reactive pressure of the fin on the adjacent flange 22 which reduces the intensity of the engagement at 23 and reduces the firmness of the contact between the tube 10 and the spacing' is shown the construction found to be most. satlsfactory and to most nearly form a per` feet heat conducting contact over the entire area of the end of the flange 22 where it engages the fin. It maintains firm heat conducting engagement between the flange 12 and the tube 10 when the tube 10 is expanded because the flange 22 is forced against the fin and the reacting force of the fin through the flange 22 holds the flange 12 in intimate contact with the tube with much greater force than the flange 22 would hold it without the aid of the'reactive force of the fin. In tbe construction of radiators of this type the fins arel assembled on the tubes and' confined at the ends of the tubes from axial movement and since each fin is engaged by an Vadjacent flange 22. creepage orl telescoping and improper spacing of the fins is prevented while the tubes 10 are being expanded into firm engagement with the spacing flanges.

Referring now to the forms of Figs'. 3. 5 and 6 as a group, one of the problems in the design of al fin type radiator is to conduct the lheat in sufficient amount from the heat tube on to the fins to utilize the full radiation and convection capacity of the fins. This is the critical point which tends to limit the capacity of the radiator.

In the usual design of finned radiator where each fin vcarries a cylindrical tube engaging flangebut no sub-flange-as illustrated diagrammatically in Fig. 9, all of the heat transferred from the heat tube to a given cylindrical flange is conducted to only one end of the flange, and thence to only one fin. The junction of the cylindrical flange to the fin thereby acts as a bottle1ieck? 28 in the cross sectional area of the fin to limit the amount of heat which can be conducted out to the fin.

The end edge of the cylindrical tube-engaging flange in theory abuts the adjacent fin unit.l but in practice it is not the kind of an abutment which affords any substantial heat conductivity. In drawing the cylindrical flange from the stock there is necessarily a rounding off` of the corner 30 against which the end of the adjacent flange is to abut, with the result that the abutment does not come along the end face of the cylindrical flange, but only touches its outer end corner 31. There is also the practical considera-tion that in actual production the end edge 31 of the cylindrical flange does not lie in a. perfectly flat plane, normal to the axis of the heat tube; neither does the rounded corner 30 where the plate of the fin joins the cylindrical flange run true. The result is that contact between the end of the. cylindrical flange and the adj acent fin unit is not even a line along the full circumference of a circle.. but is more likely to be 'only one or two short linea-r arcs o'r points. The contact in practice is therefore too incidental and occasional to afford any substantial heat conduction to the adjacent fin. Therefore. still referring to the conventionally flan ged fin. all of the heat transferred t0 the fin by the heat tube has to travel toward one end. passing through the bottle-neck region 28 and out to but a single fin.

One of the outstanding features of my invention is the provision for an effective heat conducting contact between the outer end of the cylindrical heat tube-engaging flange and the adjacent fin unit, whereby the heatfrom each cylindrical flange may be fed to two fins instead of one, whereby the objectionable bottle-necking7 of the heat flow is largely eliminated.

Referring to Fig. 10. which is a similar diagram of the specific form of Fig. 5 of my invention, the outer or free end of the heat tube engaging flange, yby reason of its subflange makes a good heat conducting contact with the adjacent fin. The outer face 31 of the sub-flange presses against the adjacent face of the adjacent fin at or radially beyond the junction of the curved surface 30 of the fin and the flat region of the fin. This is a good heat conducting surface contact because the sub-flange has acertain resiliency, and in the course of assembly the sub-flange is given an initial pressure against the adjacent fnJwhich always maintained.

It will be observed that this heat conducting Contact between the outer end of a flange and the adjacent fin is at a point well beyond, that is radially outward from, the bottleneck region 28. At the point of contact the adjacent fin has the capacity to conduct ica 1 F il.)

heat in addition to the heat which can pass the bottle-neckin region 28. This additional capacity is ue to two factors. One 1s that at the point of contact the fin is of greater 'thickness 32 than a thickness 33 of the flange l the heat transferred from the heat tube to the flange has two outlets instead' of one. Part of it goes toward the inner'end of the flange past the bottle-necking region 28 and on to the integral fin 11. The other part of it goes toward the free or outer end of the flange through the sub-flange 16 across the surface contact region 31 and on to the adj acent fin 11a. The region 31 of heat transferred from the free end of the tube to the adjacent fin is at a point on the fin where the fin has the additional heat conducting capacity to take care of the additional heat. Therefore, the heat conducting capacity of the region, which is the sum of the heat conducted by the several flanges, is not limited by the bottle-necking regions 28', as would be the case in the conventional construction of Fig. 9, but the capacity is enlarged-so that it is limited only by the thickness 32 of the fins 11, which, of course, represents a much greater conduction capacity.

In the illustrative diagram of Fig. 10, I have shown the specific form of Fig. 5. The same principle andadvantage holds for the form of Figs. 6 and 7, the difference being that the heat conducting region 31 between the sub-flange and the adjacent fin is along the line 25. As previously explained, this contact is made a good heat conducting contact over the region of the abutment. Similarly the feature holds for the form shown in Fig. 3. If the sub-flange does not directly touch the fin itself, it contacts the solder ring which is made virtually a part of the fin.

There is also the advantage in the form shown in Figs. 3, 5 and 6 that the sub-flange,

in bearing against the adjacent fin, gives a certain resiliency which takes care of any inequalities in expansion between the heat tube and the several flanges. If the heat tube be made of a different metal than the fins, such that the coefficient of expansion of the heat tube is greater than that of the fins, there would be a tendency, upon admitting heat to a cold radiator unit, to a greater longitudinal expansion of the tubes than the sum of the longitudinal expansions of the flanges. In the conventional form of Fig. 9, this would mean that the contact points 31 would be drawn away from the curved surface of the adjacent fin, with the result that there would be a complete severance of whatever little heat conducting contact there might be. As applied to the eneral form of Fig. 3, if there were no subanges 15, there would be abreaking away of the adherence of the solder to the free end of the flange.

A similar advantage, but to a lesser extent, would ,obtain even though the heat tube and the fin were made of the same kind of-metal or different kinds of metal having substantially the same coefficient of expansion. Starting with the admission of steam to a cold radiator, whatever temperature gradient there might be between the heat tube and 30 the flange would cause the flange to expand longitudinally at a slower rate and less than the heat tube, similarly by the minutest fraction of an inch pullingaway the butt end of each flange from the adjacent heat tube in 35 the absence of the semi-resilient sub-flange which I provide.

The unit described above is preferably placed in a cabinet which serves as a stack or chimney to accentuate the upward flow of air between the unit and the fins. These features are fully described in the application referred to above and further description is believed to be unnecessary.

While I have described these preferred embodiments of my invention, I contemplate that changes may be made therein-including, for example, the embodiment of the illustrated structure as a cooling unit where the flow of heat is reversedwithout departing from the scope or spirit of the invention claimed.

I claim:

1. In a heat exchange device, a tube, a heat radiating fin provided with an aperture for receiving said tube, a flange carried by said fin adapted to fit against the tube, the portion of the fin adjacent the flange being bent to form a concave annular recess, a solder ring adapted to fit in said concave recess and when fused to hold the parts in fixed and heat conducting relation, to prevent crimping, and to increase the heat transferring area.-

2. A heat conducting fin comprising a thin metal plate provided with an aperture, a flange surrounding said aperture, the connection between the flange and the plate being deformed to provide an annular groove,

a solder ring in said groove, the outer edge of the flange being bent to fit against the solder ring of the adjacent flange whereby telescoping of the flanges is prevented.

3. In a heat transfer device, a tube, a heat radiating fin provided with an aperture for receiving said tube, a quarter round concave recess in said 'fin adjacent a spaced aperture, solder in said concave recess, said solder being fused to said tube and to said fin to reinforce the joint and to increase the heat transfer efficiency thereof.

4. As an article of manufacture a,` radiating fin formed from thin sheet metal having an opening for the passage of a heat tube and an annular flange integrally formed thereon about the margin of said opening for surface contact with the peri her of the heat tube, the fin being provide at t e corner where it joins the flange, with an annular groove for the reception of a ring of heatconducting fusible material.

5. A radiator comprising a heat tube adapted to contain a heating medium, a plurality of sheet metal radiating fins having openings for the passage of the heat tube and mounted thereon in spaced relation, integrally formed flanges about the margins of said openings for heat conducting contact with the peri hery of the tube, annular grooves formed in the flanges where they join their fins, a ring of relatively fusible metal disposed in the grooves for soldering the flanges to the tube and an upstanding portion on the edge of each flange to prevent telescoping of the flanges.

6. A radiator comprising a heat tube adapted to contain a heating medium, a plurality of sheet metal radiating fins having openings for the passage of the heat tube and mounted thereon in spaced relation, integrally formed flanges about the margins of said openings for heat conducting contact with the periphery of the. tube, annular grooves formed in the. flanges and a ring of relatively fusible metal disposed in the grooves for soldering the flanges to the tube.

7. In a heat exchange device, a tube, and a multiplicity of heat radiating fins, each vfin provided with an aperture for receiving said tube, an annular spacing flange on said fin about sa1d aperture having hrm heat conducting engagement with said tube, and an annular integral reinforcing flange turned outwardly at the end of said spacing flange, the end edge of which has continuous annular abutting and heat conducting engagement with an adjacent fin.

8. In a heat exchan e device, a heat tube, and a multiplicity o heat radiating sheet metal fins, each fin provided with an aperture for receiving said tube, an integral annular spacing flange on said fin, and an annular arcuate portion on said fin about said aperture integrally joining said spacing flange to the body of said fin, an outwardly turned reinforcing flange on the end of said spacing flange, the end edge of which has direct abutting substantial surface engagement with the annular arcuate portion of an ad'acent fin.

9. n a heat exchange device, a heat tube, and a multi licit of heat radiating fins, each fin rovide with' an aperture for receiving sai tube, an annular spacing flange on said fin, an annular arcuate portion on said fin about said aperture integrally joining said i spacing flange to the body of said fin, and an fin, the line of extension of said reinforcing l flange passing outwardly of the center of curvature of said arcuate portion engaged by said reinforcin flange.

10. In a heat exc ange device, a heat tube, and a multiplicity of heat radiating sheet metal fins, each fin provided with anl aperture for receiving said tube, an annular spacing flange integral with said fin, an annular arcuate portion on said fin about said aperture integrally joining said spacing flange to the body of said n, and an outwardly turned reinforcing flange on the end of said spacing flange, the end edge of which has direct abutting engagement with the annular arcuate portion of an adjacent fin the line of exten.- sion of said reinforcing flange passing outwardly of a line normal to a'tangent at the point of engagement and forming small angle therewith.

11. In a heat exchange device, a heat tube,`

and a multiplicity of heat radiatin fins, each fin provided with an aperture or receiving said tube, an annular spacing flange on said fin, an annular arcuate portion on said finqabout said aperture integrallyjoining said spacing flange to the body of said. fin, and an outwardly turned reinforcing flange on the end of said spacing flange, the

yend edge of which has direct abutting engagement with the. annular arcuate portion of an adjacent fin, the line of extension of said reinforcing flange passing outwardly of a line normal to a tangent at the point of engagement and forming an angle therewith of less than 30 degrees.

12. In a heat exchange device, a heat tube, and a multiplicity of heat radiating sheet metal fins, each fin provided with an aperture for receiving said tube, an annular spacing flange on said fin, an annular' arcuate portion on said fin about said aperture integrally joining said spacing flange to the body of said fin, and an outwardly turned reinforcing flange on the. end of said spacing flange, the end'edge of which has direct abutting engagement with the annularl arcuate portion of an adjacent fin, the line of extension of said reinforcing flange forming a small angle with a line normal to a tangent to the arcuate portion at the point of engagement by the end of the reinforcing flange.

13. A heat exchange device comprising a heat tube, a multipllcity of heat radiating fins formed of sheet metal, each fin com rising a radiatin plate portion at substantially a normal to t axis of the heat tube and having an opening penetrated by the tube and having a cylindrical integral flange extending axially from the margin of the opening for heat conducting surface contact with the heat tube, the sheet metal of the fin at the intersection of the plate portion and the flange portion, formin a corner at the margin ,of the opening o fillet-like form whose outer radius of curvature is greater than the thickness of the sheet metal, an outwardly turnedA sub-flange at the end of the flange portion opposite the plate portion, the sheet metal at the intersection o f the subfiange with the flange portion being of filletlike form whose radius of curvature 1s greater than the thickness of the sheet metal, the end edge of each sub-flange havlng continuous annular abutting and heat conducting engagement with the fillet-like ortion of the adjacent fin, the heat tube bem internally expanded against the resistive orce of the plate portions of the fins to ensmall the radii of curvature of the fillet-like regions of the fin against the resilience thereof, whereby the fillet-like regions tend to enlarge the radii of their curvatures and thereby maintain said abutting engagement.

14. A radiator comprising a heat tube and a plurality of heat radiating fins fixed thereon in spaced relation, each fin comprising a sheet metal heat radiating plate disposed at substantially a normal to the axis -of the tube, an integral sheet metal flange conforming to the outer surface of the heat tube and in heat conducting contact therewith, a heat conducting connecting corner between the plate and one end of the fiange' and an outwardly offset annular sub-fiange at the other end of the iiange in heat conducting contact with the corner of the adjoining fin for feeding heat thereto, for spacing the fins and for lpreventing their telescoping, the sub-flange being brought into substantial parallelism with the outer surface of the corner, the lateral surface of the said sub-flange remote from its own fin lying in firm heat conducting contact with the outer surface of the corner.

15. A radiator comprising a heat tube and a plurality of heat radiating fins fixed transversely thereon in spaced relation, each fin comprising a sheet metal heat radiating plate, a flange integrally formed with the plate conformed to the outer surface of the heat tube and in heat conducting contact therewith, and an outwardly offset annular sub-fiange at the other end of the flange, the sub-flange being brought into substantial parallelism with the plate, with the surface of the sub-flange distant from its own fin plate being pressed in firm heat conducting contact against the adjacent surface of the adjacent fin plate.

16. In a radiator the combination with a heat tube and a multiplicity of heat radiating fins fixed thereon in spaced relation and penetrated thereby, each fin comprising a heat radiating plate portion of sheet metal exposed to the fiow of air through the radiator, a sheet metal flange portion integral with the plate portion and conforming to the outer surface of the heat tube and in heat conducting contact therewith and a corner portion between thc plate and flange portions for conductin heat from the former out on to the latter,o

means for also conducting a substantial portion of the heat from each fiange portion out on to the plate portion of the adjacent fin, said means comprising an outwardly offset annular sub-flange at the end of each flange portion opposite its integral plate portion, which sub-flange is held in substantial heat conducting surface contact with the corner portion of the adjacent fin at a radius from the axis of the heat tube greater than the outer radius of the heat-tube-engaging region of the flange portion.

17. In a radiator, the combination with a heat tube and a multiplicity of heat radiating fins fixed thereon in spaced relation and penetrated thereby, each fin comprising a heat radiating plate portion of sheet metal exposed to the flow of air through the radiator, a sheet metal flange portion integral with the plate portion and conforming to the outer surface of the heat tube and in heat conducting contact therewith and a corner portion between the plate and flange portions for conducting heat from the former out onto the latter, the corner portion being formed of sheet metal integral with the fin and of fillet-like cross section whose outer radius of curvature is greater than the thickness of the sheet metal,-of means for also conducting a substantial portion of the heat from each flange portion out onto the plate portion of the adjacent fin, said means comprising an outwardly offset annular sub-fiange at thevend of each flange portion opposite its integral plate portion, which sub-flange is held in substantial heat conducting surface contact with the sheet metal of the corner portion of the adjacent fin at a radius from the axis of the heat tube greater than the outer radius of the heat-tubeengaging region of the flange portion.

18. A radiator comprising in combination a heat tube, a multiplicity of fins fixed-thereon and penetrated thereby, each fin comprising a heat radiating pla-te portion ofthin sheet metal exposed to the flow of air through the radiator between the plate portions, a sheet metal cylindrical unsplit ,flange portion intgral with and drawn from the sheet metal o the plate portion and conforming to theouter surface of the heat tube and in heat conducting surface contact therewith, a corner portion between the plate and flange portion, and including the integral sheet metal connecting the plate portion and the flange portion, for conducting heat from the former out onto the latter and outwardly off-set annular sub-flange portion, also integral with and stamped from the sheet metal of the plate portion, at the end of the flange portion opposite its integral plate portion, the sub-fiange p0rtion being held in substantial heat conducting surface contact with the adjacent fin at a radius from the axis of the heat tube greater than the outer radius of the heat-tube-engagin region of the flange portion.

n witness whereof, I hereunto subscribe my name this 5th day of November, 1930.

REUBEN N. TRANE.

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