US2899178A

US2899178A - Heat exchange fins and assembly

Info

Publication number: US2899178A
Authority: US
Publication date: 1959-08-11
Anticipated expiration: 1976-08-11

Description

Aug. 11, 1959 p B ET AL 2,899,178

HEAT EXCHANGE F INS AND ASSEMBLY Filed Sept. 2-7, 1956 1 1 W mm W i "if T v Y 43 47 Maw/V DUB/N INVLAFORS #Z ls/ooes um/vs/(r A TTmOR HEAT EXCHANGE FINS AND ASSEMBLY Melvin Dubin and Isidore Turinsky, Brooklyn, N.Y., assignors to Slant-Fin Radiator Corporation, Richmond Hill, N.Y., a corporation of New York Application September 27, 1956, Serial No. 612,413

'3 Claims. (Cl. 257-26216) This invention relates to convection type heaters and is particularly concerned with improvements in heat exchange fins therefor and improvements in assemblies of such fins with pipes or conduits.

Fin constructions and the assemblies thereof with pipes in the make up of convection heaters as heretofore devised have left certain things to be desired. The fins are normally assembled on a pipe and are shipped to the job substantially ready to be installed. In the handling leading to the installation and in the installation itself, however, the actions are such that distortions of individual fins and consequent reduction in the heat co-efficient thereof are likely to take place. To overcome this the prior art approach was to make the individual tins of material of sufificient thickness and stiffness to resist such distortive action.

The making of the fins of heavier, stiifer material, in a sense, defeated itself, for their weight and stiffness made them hard to handle so subjected them to rough treatment and that, again, led to distortions.

Another drawback of the heavy fins was that invariably, due to their thickness and the actions needed to stamp them out, they were formed with sharp or rough edges and corners. Thus, they were particularly hazardous to the workmen handling them, since the sharp edges were provided on stiff and heavy members difiicult to handle and work.

Another drawback of the prior art constructions is their tendency to possess or develop what is called a reed eifect. In other words, a vibratory noise which may be present on installation and, if not, may develop and become pronounced at any time during the life of the installed heater.

The construction of the invention eliminates these prior art drawbacks and introduces additional improvement thereover as well. This is done by giving a particular formation to the individual fins so that when assembled they support each other and thus attain strength through assembly rather than through sheer weight of the individual fins. Accordingly the individual fins can be made of lighter weight material while in the assembly they present greater resistance to distortion than did the fins of the prior art. The significance of this advantage increases with increase in fin size. In fact, in actual practice it has been found that, in the larger fin sizes, for pipe from 1%" to 2" in diameter, where the fins run up to 4%" square, the thickness of the fins when made of steel can be cut from substantially .035" down to substantially .012" in thickness. Thus the principal object of the invention is to provide adequate fin constructions of substantially lighter material than has heretofore been the case.

Another object is to enable the use of such light weight fin material by particular formation and assembly of the fins so that they reinforce each other.

In forming the fins so as to engage both on the pipe and adjacent fins at positions remote from the pipe, it has been found possible to increase the fin area. Thus niteci States Patent C ice greater heat transfer is provided for, hence the external volume of the assembly can be reduced, while maintaining the heat capacity of larger volume installations of the prior art. Putting it another way, when installations of the invention of the same volume as those of the prior art are employed, the heat capacity is greater. The lighter weight material makes for better emissivity and quicker heating when the heat is turned on and heat transfer is also enhanced by the flue effect introduced by the side engagement of the fins in the assembly. It is thus another object of the invention to improve the heat exchange characteristics of the fins of convection heaters, not only through greater heat capacity but also through acceleration of heat transfer.

By the formation of the opposed pairs of fin edges of the fins in accordance with the invention, most of the edges and corners heretofore protruding to make the fins hard to handle are eliminated. The importance of this cannot be over estimated for through the combination of the elimination of sharp edges and corners and reduction in weight, installers find it infinitely easier to handle as semblies of fins and pipes in accordance with the invention. Besides handling them more readily, they also can handle them with greater care, though care in handling is really not so necessary as in the case of the prior art constructions.

Still another object of the invention, then, is to provide fins which are devoid of corners and edges and less likely to injure the installers and other handlers of the assemblies, while a further object is to render the general overall handling of the assemblies easier from a variety of standpoints.

Finally, the interlocking of the fins where they seat on the pipe and the interengagement of their pair of exterior edges puts and maintains them in constant contact in different positions, thus eliminating the possibility of vibratory noise commonly referred to as the reed effect. The elimination of this effect is one of the further objects of the invention.

Still further and more detailed objects of the invention will in part be obvious and in part be pointed out as the description of the invention taken in conjunction with the accompanying drawing proceeds.

In that drawing:

Fig. 1 is a perspective view of an assembly of fins in accordance with the invention mounted on a pipe.

Fig. 2 is a top plan view thereof.

Fig. 3 is a plan view of a fin per se.

Fig. 4 is a side elevation thereof as viewed from the right hand side of Fig. 3.

Fig. 5 is a vertical section taken on line 55 of Fig. 3 and looking in the direction of the arrows.

Fig. 6 is a fragmentary section of a pipe with fragments of fins applied thereto, illustrating the interlocking of the fins when assembled on the pipe.

Fig. 7 is a fragmentary perspective View of an assembly of fins in accordance with a modified form of the invention.

Fig. 8 is a similar view of another modification; and

Fig. '9 is a view similar to Fig. 2 showing a further modification of fins.

In the preferred form of fin and pipe construction, as illustrated in Figs. 1-5, each of the fins, generally indicated at 1 has a main portion 2 formed to extend at right angles to the pipe receiving it. At one pair of opposite edges the main portion 2 is bent backwardly in identical turned back strips 3, the bending taking place about the crease line 4. At the end of the turned back strips 3 remote from the crease line 4 the material is further bent about the line 5 into narrow inturned strips 6. The angle 7 included between the strips 6 and the strips 3 is smaller than that included between the strips 3 and themain portion 2, and, as here illustrated, is substantially a right angle. It is not essential, however, that the angle 7 be a right angle. It is merely essential that the width of the strip -6 and the angle '7 be such that the free edge 8 of the inturned strip 6 will engage the face of the next turned back strip 3, when a plurality of the fins in accordance with the invention is in properly assembled relation.

Considering that relation, it is to be noted that the main portion 2 of each fin is perforated at substantially its midpoint and drawn outwardly in the opposite direction to the extension of the

strips

3 and 6. The opening 10 of the perforation is such as to enable the fin to be seated on the section of pipe for which it is intended with a reasonable amount of drag, but freely enough to enable the fins to be applied without injuring them. This seating is enhanced by the provision of a narrow flange 11 drawn outwardly around the opening so that each fin -has a surface rather than a mere edge contact with the pipe. As best seen in Fig. 3, the hole 10 through the main portion 2 is concentrically positioned with respect to the center of said main portion and encompasses more than half the width of said main portion.

In the perforating and drawing of such flanges, each fin is also provided with identically formed and positioned fingers 12, each of which extends out from the flange 11, there being in this instance four in number at equally spaced positions around the opening. It is to be understood however that the number and shape of the fingers as here shown is merely for the purposes of illustration and that Variations therein and modifications thereof may be effected without departing from the spirit and scope of the invention.

The fingers 12, besides adding to the engagement of the fin with the pipe, also assist in the accurate locating and the maintenance of the positioning of one fin with respect to the other. This is achieved by the upward recessing of the fingers 12 at the position 13 adjacent their bases. The recesses, of course, continue across the flange 11 and are included in the border of the opening. The pockets 13 so formed matingly receive the ends or noses 14 of the fingers on the next fin to the rear. Thus, as one fin after another is slid on to a pipe, such as that shown at 15 in Figs. 1, 2 and 6, the fins are brought into proper assembly located with each other, as best shown in Fig. 6, by projecting their noses 14 into the pockets 13 formed up into the fingers 12 of the preceding fin. The relationships of the elements of the fins for this positioning are so chosen that when the noses 14 of one fin come home into the pockets 13 of the next fin, the free edge faces 8 of that next fin will come into contact with the outer surfaces of the turned back strips 3 of said one fin.

By so assembling the fins all of them in a set are accurately positioned with respect to each other and with respect to the pipe. Each one engages the other and each one assists in supporting the other. In this way, though they be of substantial size they may, at the same time, be made of steel of approximately one-half the thickness of that heretofore used for reflector type radiator elements, or they may be made of other material of less strength, such as aluminum. Nevertheless, they will maintain uniform spacing, protect one another against distortion in the shipping, handling and installation of assemblies of them and they will present other advantages as well. The continuous contact of them will eliminate the musical instrurnent reed effect which the prior art constructions are inclined to adopt, either as installed or unexpectedly at some future time. Then, and of material importance, is the fact that by the provision of the turned back and inturned strips, the fins provide greater heating surface than do the prior art fins devoid of any such construction. Also, for protection to the installer, there is the factor of the substantial elimination of the sharp corners found in the prior art fins. Nevertheless, there is no interference with the path for air to pass up through the assembly and be heated as it passes. I

In the modified form of fin shown in Fig. 7, each main portion 20 has a turned back strip 21 at a pair of opposed sides thereof. Such strips are bent at an angle about the crease line 22 substantially the same as the angle 7 of the form of Figs. 16. The ends of the turned back strips 21 remote from the main portion 20 carry the inturned strips 23 which are formed by making a further and sharper bend at 24. As in the form of Figs. 1-6, the included angle here may be approximately a right angle, though that angularity-canbe varied as heretofore pointed out.

The important difference in the Fig. 7 modification is that the inturned strips 23 have their free end edges recessed at a plurality of positions 25, here illustrated as two in number. These provide spaces allowing air to pass through the sides as well as from top to bottom of the assembly. Nevertheless, the unrecessed portions of the free edges engage the outer surface of the adjacent turned back strip .21 to achieve the same locating and positioning effect as do the unrecessed inturned strips 6 of Figures l-6. Alternately the unrecessed portions may enter receiving perforations in the adjacent turned back strip 21.

The modification of Fig. 8 is generally similar to that of Fig. 7, each fin having a main portion 30, turned back strips 31, and inturned strips 32. Here the free edges 33 of the turned back strips are formed with undulations, the peaks 34 of which will engage the adjacent turned back strip 31, while the valleys 35 will depart therefrom and will provide air passages, the same as is done by the recesses 25 in the Fig. 7 construction.

The modification of Fig. 9 proceeds a little differently. Here the pipe 40 is shown as having a plurality of fins, generally indicated at 41, applied thereto in assembled and engaged relation. As in the previous forms, each fin has a main portion 42 which is perforated at approximately its center, has a flange 43 drawn out around such perforation, has teeth 44 extending outwardly from the flange and has upwardly recessed pockets 45 to receive the noses of the teeth carried by the preceding fin.

Importantly here, however, is the fact that instead of the abrupt bends of the previous form, one opposed pair of edges of each main portion 42 is turned backwardly in rearwardly and inwardly turned portions 46 which are merely smoothly curved extensions of the main portions 42. The curvature here is so chosen that the free edge faces 47 of the curved portions 46 of one fin engage the exterior of the curved portion 46 on the adjacent fin when the fins are properly assembled on a pipe. The whole construction thus has a smooth pleasing appearance, is devoid of any sharp angles and bends and facilitates handling. The curved portions provide additional surface for heat transfer while retaining the assembly strength and all the other desirable characteristics of the Fig. 1 form.

In the foregoing description and in the accompanying drawing, preferred and various modified embodiments have been disclosed employing the principles of the invention. It is, of course, to be understood that these showings are for illustrative and not limiting purposes and it is appreciated that one skilled in the art, upon considering the foregoing might well devise variations or modifications thereof still falling within the spirit and scope of the invention.

Speaking generally then, it is to be understood that since certain changes may be made in the above article and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing, shall be interpreted as illustrative and not in a limiting sense.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

1. A heat exchange fin formed of light weight sheet metal material which comprises, a main portion and side Portions extending from a pair of the opposite sides of said main portion, said side portions extending rearwardly and inwardly from and with respect to said main portion, said side portions each being formed of a plurality of flat strips extending at abrupt angles with respect to each other and to said main portion, the first of said strips departing from said main portion at an obtuse angle greater than a right angle and at substantially the mid position between the center and edge of said fin and the second of said strips departing from the first of said strips at substantially a right angle, said main portion formed with a hole therethrough for the reception of a pipe, said hole being concentrically positioned with respect to the center of said main portion and encompassing more than half the width of said main portion.

2. In heat exchange construction in combination, a pipe and a plurality of fins carried by said pipe, said fins being formed of sections of light weight sheet metal and each of said fins including a main portion and extending portions at a pair of opposed sides of said main portion, said main portion being formed to receive and engage said pipe and said extending portions being turned away from said main portion, said extending portions including a first strip extending from said main portion at an abrupt angle greater than a right angle and a second strip extending from said first strip at an abrupt right angle, said second strip terminating in a free edge face lying in a plane at right angles to the plane of said second strip and the free edge faces of one fin making surface contact with the flat outer surfaces of the said first strips of the next adjacent fin.

3. Heat exchange construction as in claim 2 and said second strips being formed with recesses therein.

References Cited in the file of this patent UNITED STATES PATENTS 1,950,112 Iacocks Mar. 6, 1934 2,557,760 Powell et a1 June 19, 1951 2,786,653 Martin Mar. 26, 1957 FOREIGN PATENTS 332,471 France Oct. 6, 1902 776,001 France Oct. 22, 1934