US2592950A - Heat exchange core - Google Patents

Description

PY115, 1952 s. PRzYBoRowsKl 2,592,950

HEAT EXCHANGE CORE Filed Sept. 24, 1948 2 SHEETS-SHEET l l@ givin@ IWl llll'- l Wim-m www-mm v Ivi, ni

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(Ittorneg April 15, 1952 s. PRzYBoRowsKl HEAT EXCHANGE CORE 2 sl-xEETs-SHEET 2 Filed Sept. 24, 1948 Patented Apr. 15,r 1952 HEAT EXCHANGE CORE Stanislaus. Przyborowski, Kenmore, N. Y., as, signor to. FeddeIs-Quigan Corporation, Buffalo,

N. Y.,k a. corporation of New York Application September 24, 1948, Serial No. 50,975

This invention relates to a heat exchange apparatus, and it has particular reference to the provision of an improved iin and tube core particularly adapted for use as an automobileradiator, car heater, or the like.

More specically, the present invention is concerned with an improved heat exchange core of the type wherein spaced tubes are positioned y between spaced headers or manifolds, and ns interposed between the tubes. and headers are formed by bending a strip of metal into generally zig-zag shape. A liquid, either relatively nonvolatile, such as Watenor Ahighly volatile, such as a refrigerant, may be` circulated throughthe tubes by inlet and outlet connectionsl on thel manifolds, to effect a heat exchange function with an air stream passing through the open gaps between the successive folds of the fin strips. Cores of this nature nd application in the cooling of automotive engine coolants, heating the air in the car body, condensing hot compressed refrigerant vapor, and the like. The nature of the improvements, and the advantages attaching thereto, will be made apparent as this description proceeds, and the novelty will be pointedout in the appended claims.

In the drawings:

Fig. 1 is a generalized view of the rear face of the core as applied to an automobile engine radiator;

Fig. 2 is a side View of the radiator shown in Fig. 1;

Figs. 3 and 4 are enlarged fragmentary sections, taken on the line A-A of. Fig. 2, and respectively showing modified :forms of tube dis-l position;

Fig. 5 is, a front elevation, on anv enlarged scale, of' a portion of an improved n strip;l

Fig. 6 is a view similar to Fig. 5,r but showing a greater number of folds brought proximity;

Fig. 7 is a view similar to Fig. 5, showing a modification in the formation of thefin strip;

Fig. 8 is a View, similar to Fig. 6, of' then of Fig. 7 whencompacted between a pair of spaced A into closer'V L Claims. (Cl. 257-130) spaces between adjacent tubes, and thus provide air passage cells. In the forms illustrated in Figs. 2, 3, and 4, the core is three tubes deep from face to face, but it should be understood that a greater or less number may be employed. The fins, tubes, and headers are connected to each other by dipping in a bath of molten solder, tinning and heating in a furnace, brazing, or the like, all of which is well understood. When assembled and integrated, liquid may iiow into and out of the manifolds Il or I2 through connections attached to fittings i5 and IB', while air may flow through the spaces or cells between the folds of the ns, thereby to eiect the desired heat exchange.

Referring particularly to Fig. 3, it will be seen that each foldA 2i of the fm strips I4 is formed, beginning a short marginal distance from front and rear edges, with a series of protuberances and depressions, or bumps, 22, 23, which project alternately in opposite directions from the plane of the fold. The bump 22 is shown as depressed into the plane of the paper, and therefore appears as a depression, while the .bump 23 is shown as elevated, or as a protuberance. If the fold were viewed from the opposite side, then, of course, the depressions and protuberances would be reversed. In the direction from face to face of the core, the bumps merge into each other, as is indicated in Fig. 9. Each bump 22 or 23 overlies a similar bump in the next adjacent fold, -and thus, from face to face of the core, there is provided an undulatory air path.

In the transverse direction, each bump is arcuate along its centersection, as Will be more readily apparent from Fig. 5, rising from edge to median and then decreasingv to the opposite edge of the fold, to provide bumps all having the same height. Inasmuch as the underside of any bump formseither a depression or protuberance spaced from the immediately underlying protuberance cr depression of the next fold, it will be readily understood that, in a section taken through the bump centers longitudinally of the n, the arcuate lines merge into each other at the fold edges, to dene an u-ndulatory or more cr less sinusoidal arc whose points ofV inflexion, or reversal of curvature, lie in the edges.

It will also.. be noticed that the folds are laterally offset, to provide straight` edge sections 24 against which the tubes I3 abut, and angularly disposed short spacer Sections 25. These oisets are not very large dimensionally, but are sufficient tov displace the tubes I3 approximately onethird to one-halfl a tube thickness, thereby plac- -automobile radiator.

ing the tubes in staggered relationship. At the points where the offsetting occurs, the adjacent bump 22 or 23 becomes slightly deformed, due to the action of the forming rolls or dies in displacing the metal. In Fig. 3, the offsetting of the folds is shown as progressing in one direction, while in Fig. 4 the offsetting is first in one direction and then in the other, and the offset distance is varied, so that no one of the tubes between any pair of ns is in alignment with any other between the same pair.

As also clearly shown in either Fig. 3 or Fig. 4, the tubes I3 are grouped into rows from face to face of the core, and are slightly staggered or offset by reason of the displacing of the folds. Each tube, which is relatively wide and of relatively narrow breadth, is located against the n edges with the long dimension at right angles to the core faces, or with the narrow dimension disposed transversely thereof. While the tubes are thus staggered, they nevertheless overlap each other in the transverse direction, inasmuch as the offsetting is less than the tube breadth. They are also spaced from each other by the offset portions 25, which provide abutments to facilitate assembly and supports when the core is completed to resist adventitious displacement of a tube.

It has, of course, heretofore been proposed to provide secondary heat exchange surface in the form of spacer ribbons, in which the metal is deformed with bumps from face to face of the core to provide an undulatory air path. This is illustrated in my prior Patent No. 2,016,822 of October 8, i935, in which is described a cellular In the present instance, an even more effective air path is provided by causing the air to move in an up and down undulatory path and simultaneously displacing the air flow transversely. Whether this be explained on the hypothesis of turbulence or throttling of the air stream, the fact is that by offsetting the iin folds, and thereby placing the tubes in staggered arrangement, a more effective utilization of the air is obtained, thus adding to the capacity.

Another feature of the present iin ribbon is the extension of the bumps 22 and 23 to the edges of the folds, as is somewhat better shown in Figs. and 6. After the ribbon stock has been deformed to provide the bumps and offset portions, it is gathered or folded into the generally zigzag form shown in Fig. 5, and it may thereafter be compressed to bring the folds more closely together, as shown in Fig. 6. For an automobile radiator core, the tubes I3 will be spaced by the ns a distance of about half an inch, and if effective heat transfer is to be obtained, the tubes must tightly abut the fins at the straight edge portions 24 between adjacent folds. This means that the edges of the fins, designated by the reference numeral 26 in Figs. 5 and 6, are inclined to each other at an angle, which of course becomes progressively more acute as the fold spacing is decreased.

It has been discovered that, unless the fins are so constructed as to provide substantially fixed hinges at the junctionsl of the folds, then, upon bending to folded form, the actual line of bend will shift irregularly. It will be seen in Fig. 5 that there is a broken straight line T tangent to all bends, which represents excellent contact, and hence good heat transfer, between the fins and the tubes. In the instance of irregular shifting just referred to, the condition would be that one or two of the bends might have the desired contact, but the next adjacent would either be spaced from the line T, or attempt to overlap it. With such irregular and uncontrollable displacements, all tubes cannot contact all iin edges in the desired manner, the core capacity therefore not only becomes less than desired, but it also becomes an uncertain variable.

Accordingto the present invention, the extension of the bumps 22 and 23 to the edges of the folds imparts a measure of reinforcement to the metal, except at the actual region of bending, designated by the numeral 21 in Fig, 5. When the ribbon is pleated, there is therefore only a very limited distance between successive folds through which the bend can be made, and this limited distance constitutes the xed hinge just referred to. Inasmuch as the ribbon will bend along its line of least resistance, or the region 21, the folds will be uniform and the edges will be vertically aligned to contact the tubes uniformly. The provision of the hinge lines also permits some variation of the fold spacing without change in the forming dies.

In the form shown in Figs. '7 and 8, the fins are provided with a series of folds 3l each having bumps 22 and 23 extending from edge to edge, as heretofore described. The hinge or bending section 32, however, in distinction to the bend section 21, is formed with an arcuate ridge 33 of short radius by outwardly creasing the bend section at this point. This further enforces the bending of the fins along predetermined lines to assure the desired uniformity of contact .with the tubes I3. The transverse edge 34 of the iin will therefore appear to merge into the arcuate ridges 33 through short connecting links 35, although the bumps 22 and 23 are contiguous with the ridges 33, reversing their direction of curvature at the ridges. It will also be understood that the fin shown in Figs. 7 and 8 is also transversely offset, as explained in connection with Figs. 3 and 4.

After the ribbons have been formed, they are bent at the hinge portions to provide the series of folds, and are compacted to the extent required. Inasmuch as the bend line or hinge 21 or 33 is sharply defined, the fins readily retain their setting, whether it be say eight, ten, twelve, or even more folds per inch, and do not tend to expand in spring-like fashion when released from the spacing tools. They may, however, be readily extended or further compressed, to provide Wider or closer spacing. This feature is advantageous, not only in the handling of the fins during assembly, but also when it may be desired to make a change of one or two folds per unit length of tubing. After forming, the ns and I'tubes are laid one on the other until a core of the desired size is formed, and the ns and tubes are then bonded to each other in any of the well known manners.

The comparatively thin or hair line contact between the edges 21 or 33 and the side walls of the tubes I3 has been found to be beneficial in providing tight joints with a minimum of solder. Under the compressive force required to hold the core elements in place during soldering, the several hinges or junctions between the folds bite into the tube walls, thus providing joints of limited area, and accordingly decreasing the amount of solder required. Such tight joints are also effective in providing for heat transfer from the tube walls to the fin folds, inasmuch as there is less tube surface whose thickness is increased by the n stock thickness.

While the invention has been described with reference to a few embodiments, it will be understood that it is not intended to limit it to any single one of them, or to exclude from its scope such variations and modifications as are encompassed by the following claims.

I claim:

1. A heat exchange core comprising spaced headers, a plurality of independent tubes having a narrow elongated cross section positioned between the headers, said tubes being grouped in rows from the front to the back of the core with their narrow dimension disposed transversely, the tubes in each row being offset from each other a distance less than said narrow dimension, said rows of tubes being spaced transversely of the core a distance greater than said narrow dimension, and continuous ns disposed between said rows and bonded to the tubes of adjacent rows, each of said fins comprising a strip of metal ribbon bent back and forth on itself to provide a plurality of spaced folds joined to each other by narrow edges, substantially imperforate bumps extending over the surface of each fold from the front to the back of the core, said bumps merging into each other, said bumps projecting alternately in opposite directions from the front to the back and between said narrow edges dening the limits of each fold, said narrow edges having straight portions having a length substantially equal to the long dimension of the tubes, said straight portions being connected by oiset portions, whereby said narrow edges engage all of the tubes in said offset rows.

2. A heat exchange core comprising spaced headers, a plurality of independent tubes of narrow elongated cross section positioned between the headers, said tubes being grouped in spaced rows from the front to the back of the core with their narrow dimension disposed transversely, and continuous metallic fins disposed between the rows and bonded to the tubes of adjacent rows, each of said fins comprising a strip of metal bent back and forth on itself to form a series of spaced folds of equal width and having narrow edges engaging the long dimension of the tubes in adjacent rows, said folds being formed to provide a series of substantially imperforate bumps extending from the front to the back of the core between said rows of adjacent tubes, said bumps merging into each other, adjacent bumps on each fold projecting in opposite directions from the plane of the fold, each of said bumps overlying a bump on an adjacent fold which projects in the same direction, thereby to form an undulatory air path between adjacent folds, said overlying bumps, in a direction longitudinally of the n. having center sections dened by undulatory curves whose points of inflexion lie in said narrow edges, said narrow edges constituting hinge lines about which said folds are bent.

3. A heat exchange core as set forth in claim 2, wherein said folds and said narrow edges are laterally offset between the tubes in each row a distance less than the breadth of the tube, thereby placing said tubes in staggered overlapping relation.

4. A heat exchange core as set forth in claim 2, wherein said narrow edges are outwardly creased to form ridges engaging the sides of the tubes and sharply defining the hinge lines.

STANISLAS APRZYBOROWSKI.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,401,918 Neveu Dec. 27, 1921 1,417,087 Mathes May 23, 1922 1,522,404 Albach Jan. 6, 1925 1,611,894 Diamant Dec. 28, 1926 1,950,488 Gillean Mar. 13, 1934 2,016,822 Przyborowski Oct. 8, 1935 2,061,100 Palmer Nov. 17, 1936 2,083,671 Schutt June 15, 1937 2,106,091 Foster Jan. 18, 1938 2,252,211 Seemiller Aug. 12, 1941 FOREIGN PATENTS Number Country Date 450,747 Great Britain July 23, 1936

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