US2089340A - Extended fin surface for conduits - Google Patents

Description

Aug. 10, 1937. J. F. COBB l EXTENDED FIN SURFACE FOR CVGNDUITS Filed Jan. 19:, 1932 y iNvENToR Patented Aug. io, 1937 t 2,089,340

UNITED STATES PATENT oFFlcE EXTENDED FIN SURFACE FOR CONDU'I'IS James Forrest Cobb, Portland, Orcg., assignor to 'Mlore Dry Kiln Company of Oregon, a corpora on Application January 19, 1932, Serial No. 587,536

'16 Claims. (Cl. 257-262) My invention relates to improvements in tins v Figure VI `is a vertical sectionalong the line for pipes or conduits and yhas for its main object VI-VI, of Figure V, also -showing a common the production of a nov'el fin and novel means supply header. y for superimposing it on pipes or conduits con- Referring to the numerals on the drawingi taining a heating ora cooling fluid. indicates a iin, made preferably from a piece of 5 An object of my invention lato provide a reresilient sheet metal, a number of which ns movable fin with resilient means which will give may be superimposed in series on a conduit 2 as sustained intimate contact with a pipe or conduit. illustrated inFigure III.

Another object of my invention is to provide a Attention is called to the shape of the nn I ilnovel design of shape which will transmit heat lustrated in Figure II, which is a preferred form. 10 eillciently from a iluid within the conduit to the By means of a stamping process an intermediate atmosphere surrounding the conduit, or from the portion of a Sheet metal plete (lished at '0.011 atmosphere to a uid withinthe conduit. one face, lies between a preferably flat outer Another object of my invention is to provide flange 5 and a partite medial section having na single unit of annular shape which I call a fin, gers l formed around the periphery of a medial 15 for a conduit which fin will nest with another fin opening l ofthe fin l, and projecting laterally at either of lts sides, in assemblage on a conduit, from one of its faces, the inner surfaces of said whereby heat transmission between a surroundingl fingers conversing for example, along the lines i3. atmosphere and a fluid within vthe conduit is pro- The n iS preferably mode from metallic Sheet moted. having high resilience, and conductivity. The re- 20 Another object of my invention is to provide a sillones or elasticity is an essential characterfin having an extended annular flanged surface istie of the fingers 3. for a fluid containing conduit, and having a par- The intermediate portion I0 of the nn is dished tite medial section comprising individually resilion one of te feces, or otherwiseV Shaped in any 'ent fingers spaced around a medial opening, the manner preferable to render the outer flange fingers -maintaining intimate mutui; with the surface 5 of the iin I relatively inflexible. This 25 conduit regardless of expansion or contraction 1S accomplished by annular bends. for example1 due to heating or cooling of the fins or the conat 8, and 8 which are respeotlvely preferably 1111iduit. formly spaced from the outside periphery of the Another object of my invention is`to provide a iin I when it is substantially round as illus- 30 nu for a conduit more emoieut for neat transfer. trated in the drawing. These bends produce in between the conduit and the iin because of their 6390i o Corrllsaiiion in the Surface of each side having greater and better surface contact. 0f the ll- Cther objects of my invention will be made ap- It iS understood that the fins may be of any f parent to one skilled in the grt 1mm the goldesired shape. They are illustratedas being sub-l 35 lowing specification: stantially round. but they may be made sub- What constitutes my invention will be herein- Stnlilly Square. hexagonal. elliptical, or any after described in detail' and succinctly defined desired Peripheral Shape. It is understood also in the appended claims, that the shape of the nn'may be individually 40 In the accompanying drawing wherein I il- Vliedasdeslrei 40 lustrate my invention in present preferred form The lingers 3 are illustratedv as forming lateral of embodiment, extensions from preferably one face of the n,

. Figure I is a plan view of o, pnl-viewed from their inner surfaces converging, before being su- I one of its faces; l perimposed on the conduit. In Figures I and 45 Figure 1I is a, cross geotion along the line the innei` surfaces i5 of the fingers are shown 11-.11 of Figui-e1; Y rounded to t the round external surface of a Figure 111 is a side eievation of, an ampipe for example. It is understood that similar blage of ns, illustrated in Figure I, mounted on lingers may be made to conform totthe outside a pipe. I. surface of a square vor rectangular conduit. The Figure IV is a partial plan View of onef my conduit may be of any preferred shapeln cross, 50 nus illustrating certain features of its construeectliop. suches round, elliptical. or having paraltion. el s des.

Figure V is a horizontal cross section of a plu- Attention is called to the slits i2 between 1inrality of vertical conduits havinga iin common sers- These slits, spaced at intervals. preferably 55 to all of them superimposed thereon. extend laterally or radially as illustrated in Figure 55 I from the medial opening 4 beyond the point of contact of the fingers 3 with the conduit, and preferably extend across a flat surface i4 of the fin, the plane of which surface is shown, for example, at substantial right angles to the conduit. However, this angle is immaterial.

Before the finis-assembled on a conduit the laterally extending fingers 3 in Figure II have their inner surfaces converging, illustrated by the numeral il designating the median lines of said surfaces of opposite fingers. In other words, the distance between the tips 8 of opposite fingers is less than the distance between their inner surfaces 1, which have preferably substantially. the same radius I8 of inner curvature as the outer surface of the conduit. This convergence makes it possible to spring the fingers outwardly` within their Velastic limit so that these median lines I3 will be substantially parallel to each other when the fins are assembled on a conduit as shown in Figure III. The resilience of the fingers permits their springing, and causes them to grip the surface of the conduit along their inner surface extending from 6 to 'i on the finger with sustained pressure, thus permitting large contacting areas and greater heat transfer between the fin and the conduit.

The individual substantially flat base I4 for each finger is an essential feature of my invention, its function being to provide greater individual spring action of the fingers 3 at the base of each, whereby the laterally extending inner surface of each finger of the fin will more firmly grip the pipe or conduit 2. The slits are preferably made by shearing the surface of the plate between fingers and bending their inner ends laterally to form the finshown in Figure I. I'he slits tend to open when the fins are assembled on a conduit, due to the springing of the fingers outwardly to permit their inner surfaces to contact the conduit surface. Attention is called in Figure IV to the trapeziform shaded area which is shown for purposes of illustration only, as defining the base Il of each finger 3. This shaded area defines a substantially fiat area of the fin which is free to flex within the elastic limit of the material used in the finger, thus facilitating assembly of ns on the conduit making it possible to maintain greater pressure of the fingers against the conduit and therefore greater conduction of heat between the fin fingers and the conduit. This trapeziform area is bounded by the slitsfl! and imaginary lines drawn across the flat surface parallel to a line tangential to the conduit.

It is understood that the fiatsurface i4 may be of any size or shape, the main object of it being-to provide greater elasticity of the fingers. When highly resilient metal is used to form the fins the fiat surface Il may be reduced t a narrow area extending transversely across theA base of each finger between the slits I2, which will, as an axis of flexion, give the necessary elasticity and resilience to the fingers.

When the circular fins are nested on a pipe as illustrated in Figure III, a triangular space l1 is provided between the fingers leaving the conduit surface exposed therethrough, providing direct heat transfer between the surface of the conduit land the surrounding atmosphere.

It is understood that in case the conduit 2 is rectangular` in cross section, the slits I2 of some of the formed fingers may be parallel to eachV other, or not, as desired. In this case or in the case of the circular fin illustrated, resilient fingers are essential. The fiat surface area gives resiliency to the fingers. y

Attention is called to Figure III which is a View of three juxtaposed fins assembled on a pipe 2. In this position the tips I of one fin set firmly against the outer surface of the bend It of Vanother fin.

As shown in Figures IV and VI in some embodiments of my invention the tips of the fingers l may be made wedge shaped in median section as shown at Il, if desired to fit against the outer surface of the bends I6 to give greater contact between fins.

By superimposing and welding one fin on a conduit, and by superimposing and jamming successively, additional fins in a nested arrangement, a tight assemblage of the fins on the conduit 2 is provided, and therefore a more etiicient transfer of heat between the fins and the conduit is made possible. 'I'he last fin or fins on any one conduit mayalso be welded to the conduit.

In the assemblage, the ends of the fingers of one fin are preferably wedged against the bend i6 of the fin ahead of it. The resilience of the fingers being augmented by the wedged assembly of the fins to give greater contact between the fins and the conduit. This wedging, illustrated in Figure VI, is effected in the assemblage of fins as they are pressed on a conduit. The tips l of the fingers 3 are jammed into the wedge shaped space between the surface of the conduit and the outer surface of the bend I6 of the adjacent fin. The tips may be wedge shaped as illustrated at Il in Figures IV and VI or they may be blunt as in Figure II. In juxtaposed assemblage the outer surface of the rounding `bend I6 holds the tip of the fin in the wedge shaped space provided thereby, iirmly against the conduit.

In the process of heating and cooling, the conduit and the fins will expand and contract. 'Ihe individu-al resiliency of the fingers makes it possible for the fin to maintain a sustained gripping contact with the conduit regardless of expansion and subsequent contraction.

The slits define two sides of the base of each finger and make possible the required resiliency, which is an essential feature of my invention.

The tight assemblage of the fins on the conduit does not impair the individual resiliency of each of the fingers, which permits them to maintain a sustained contact pressure on the conduit regardless, for example, of variable pipe size which is characteristic of commercial pipe, or changes in its size, caused by temperature changes of the fluid therein. Y

These fins may be used to increase the heating effect of conduits wherein a hot fluid is carried within the conduit and which heats the conduit wall by conduction; the pipe wall in turn .heats the rfin fingers by conduction and the fin itself by conduction and radiation; and the fins in turn heat atmosphere surrounding them by conduction and radiation.

The fins may be placed at any preferred interval on the conduit. They may be dished or bell shaped, they may be made in halves, or they may be made for attachment to two or more conduits, as illustratedin Figures V and VI, the resiliency of the fingers always remaining an important feature.

The fins may be made of copper, aluminum, steel or any other suitable material and their thickness may vary to suit the heat transfer conditions of the material that is used.

These fins are also useful for a piping system used for cooling as well as for heating.

When preferred the fins may be made in halves or any number of parts and welded or otherwise joined together for assembly on the conduit. In this case the assembled fins on the conduit would have fingers in substantially the same relationship to the conduit as illustrated in Figures I, II and'IV. 'I'he same individual resiliency of the fingers of the assembled iin would be present and exert a sustained pressure by surface contact with the conduit, as if the fin were made as a unit as shown in Figures I and II.

In some cases I prefer to make a number of fingered openings in one stripA of metal or other suitable material to be used as a common iin for a plurality of conduits which are connected to a common header 20, having a supply pipe 2i. In this 'case the extended surface may be substantially as illustrated in Figures V and VI.

It is understood that this invention is not limited to the exact design and form illustrated and described. Modifications of the principles herein described are self-evident to those skilled in the art; therefore, it is to be understood that the invention includes within its scope whatever changes fairly come within either the terms or the spirit of the appended claims.

What is claimed is:-

l. A fin having an extended, annular, plate surface, for a fluid containing conduit, a medial opening in said fin, a plurality of fingers extending laterally from one of its faces and distributed peripherally around said medial opening through which the conduit is inserted, the said fingers having surfaces in contact with the outside surface of said conduit. said fingers having a tendency to converge inwardly, and each of said iingers having a resilient base area consisting of a poi-tion of the plate with slits on two sides whereby sustained contact pressure is exerted by said fingers against the surface of said conduit.

2. A fin providing an extended surface for a conduit, said fin comprising an annular laterally extending plate with an opening centrally disposed therein, said opening having around its periphery a series of fingers projecting laterally from one of the faces of said iin, the inner surfaces of said fingers converging, each finger being separated from the adjoining fingers by a slit extending from the end of the finger across a substantially fiat area of the plate, the area be-v conduit, the combination of an annular dished laterally extending plate, a series of fingers, the ends of which have inner surfaces tending to converge and extending laterally from one of its faces around the periphery of a centrally disposed opening theren, each finger being integral with a resilient base area of said plate which is bounded on each of two sides by a slit, whereby each finger individually has gripping contact on one of its surfaces with the outside surface of said conduit providing greater heat transfer between said conduit and the atmosphere sur rounding said iin. f

4. In a fluid containing conduit, the combination therewith of a fin formed of an extended, annular plate, a partite medial section thereof comprising laterally extending fingers with inner surfaces in contact with the surface 'of said conduit, said plate lhaving a resilient base area for each of said fingers, each separated from the next adjacent base areas by slits, each base area being in tension on the side of the finger adjacent to the conduit, and in compression on the side of the finger away from the conduit, whereby individual sustained contact pressure is maintained by each of said fingers against the surface of the conduit regardless of changes in the size of the f'ln or the conduit due to expansion land contraction.

5. In a fin, an extended annular plate having a medial opening for a substantially round fluid containing pipe, ngers extending substantially perpendicularly from said plate and distributed around the medial opening, said plate including a resilient base portion for each of saidv fingers, each base portion lying between two slits in the plate, the inner surfaces of each of said fingers being rounded to fit the outside surface of the pipe, and said fingers having a tendency to converge inwardly to maintain gripping contact with said pipe under the influence of said resilient base portions.

6. A fin, formed of an extended annular plate, said fin having a partite medial section with an opening therein for a conduit, said medial section comprising fingers integral with and extending substantially perpendicularly from said plate to outwardly around a medial opening, each of said fingers having a resilient base portion, the ends of saidfingers converging to bring the end of each finger into close contact with the outer sur face of the conduit.

8. On a conduit the combination of a series of juxtaposed fins, each fin comprising a dished flanged surface, said vfins each having a partite medial section comprising laterally extending fingers curved on their inner surfaces to fit the surface of said conduit, said flanged surface comprising substantially fiat base areas having slits on two sides which extend between said fingers,

eachfinger being in tension on its surface adjacent to the conduit and 'in compression on the surface away from the conduit, whereby greater sustained contact pressure is effected by said nngers against the surface of the conduit.

9. In a heater, the combination of a conduit, a series of fins superimposed on said conduit, said fins each having a plate extending laterally from said conduit and individually resilient fingers having surface contact with the surface of said conduit, said plate being slitted to form ajacent fln may be jammed into said space and held against said conduit.

10. A radiator n comprising a plate and a plurality of individual laterally extending fingers around a medial opening therein, said plete com- 10 spring action, denned as a plate provided with a central opening therein, they said opening being bounded by a. plurality "of spring fingers slitted from the plate on lines that radiate from the central part thereof and bent outwardly, each 15 finger being joined to the main plate by a slit defined base area that is integral with the plate and the finger.

13. A radiating fin for a pipe, formed by dishing the center of a plate, placing radiallsllts in 20 the dished portion that intersect in the center todetine lingers and medally bending the iingers normal to the plate to delimit a pipe opening surrounded by short finger points, each provided with a slit defined spring base area. 25 14. A fin for a pipe, comprising in unitary structure a plate provided with a central dished area. intersecting radial slits in the dished area to denne a plurality of fingers, the points or which are bent outwardly, normal to the plate, to define an opening for a pipe, with each finger thus provided with' a slit deiined unbent spring base area.

15. A pipe iin defined as a plate provided with intersecting radial slits formed in a centrally disposed area to define a plurality of slit defined spring fingers, the said fingers being medially bent outwardly to a plane normal to the plane of the plate. to form apipe opening surrounded by the spring lingers.

16. A radiating fin deiined as a plate provided with a plurality of radial slits that intersect at the center to detlne lingers which terminate short of the outer boundary of the plate, the said fin gers being bent outwardly to dene a circular pipe opening, at a point short of the determinant ends of the slits to define a base area that acts as a spring support for the linger of which it forms an integral part.

JALIES FORREST COBB.

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