EP0169610A2

EP0169610A2 - Heat exchanger fins and method of making

Info

Publication number: EP0169610A2
Application number: EP85201142A
Authority: EP
Inventors: Roelf Jan Meyer
Original assignee: Stirling Thermal Motors Inc
Current assignee: Stirling Thermal Motors Inc
Priority date: 1984-07-23
Filing date: 1985-07-09
Publication date: 1986-01-29
Also published as: EP0169610A3; JPS6142436A

Abstract

Fin structure for a heat exchanger is fabricated by folding a strip of material back over itself at locations along the length of the strip such that integrally joining one of the folds on opposite sides are first confronting portions each of which in turn integrally joins by a further fold with a corresponding second confronting portion of the strip. Each pair of first and second confronting portions are processed to form a fin which has an interior space by joining their margins. This joining extends from the fold which integrally joins the first and second confronting portions substantially to the one fold. The one fold is deformed by displacing material from it more fully between the two fins, and preferably this is done at both ends of the fold. The displaced material strengthens the structure and spaces the fins apart.

Description

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to the general subject of heat exchangers. More specifically it relates to a finned heat exchanger structure and a method of making same.
A heat exchanger often comprises fins which promote transfer of heat, making the heat exchanger more effective. In order to further enhance the effectiveness of the heat exchanger it may be desirable for flow to take place through the interiors of the fins themselves.
The present invention is in one respect directed to a new and improved construction for heat exchanger fins which have interior spaces so that heat can transfer through the fins between a medium in the interiors of the fins and a medium exteriorly of the fins.
In another respect the invention is directed to a new and improved method for making this type of heat exchanger fin..
It is also desirable to have economy in the manufacture of heat exchange fins, yet at the time produce a heat exchange structure which, in use, will perform efficiently and with durability.
The present invention in a further respect achieves this desired result.
Other attributes of the present invention are that it offers economy in use of materials and manufacturing and it is adapted to automated manufacturing procedures. Succinctly it may be said that the invention provides for the economical fabrication of an effective multi-finned heat exchange structure from a single strip of material so as to be well suited for cooperative association with other component parts of a heat exchanger.
The present invention arises through the recognition that by applying certain steps in the fabrication of a heat exchange structure from a metal strip, it is possible to provide adequate spacing between adjacent fins without the use of additional structural parts and in doing so achieve an effective and durable heat exchange fin construction. The finned structure constructed from the metal strip is typically associated with one or more additional component parts to complete a desired heat exchanger construction. Particularly, the completed structure may have flow passages through the interiors of the fins, and/or provision for mounting of the structure.
The foregoing features, advantages, and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose a preferred embodiment of the invention according to the best mode contemplated at the present time in carrying out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a fragmentary perspective view illustrating a representative construction at one stage in a typical manufacturing procedure of heat exchanger fins according to the present invention.
Fig. 2 is a fragmentary perspective view similar to Fig. 1 illustrating the representative construction at a further stage of the procedure.
Fig. 3 is a perspective view taken generally in the direction of arrow 3 in Fig. 2 at another stage of the procedure.
Fig. 4 is a top plan view illustrating a further stage in a typical procedure.
Fig. 5 is a view on an enlarged scale looking in the direction of arrow 5 in Fi^g. 3.
Fig. 6 is a view similar to Fig. 5 illustrating representative construction at a further stage of a typical procedure.
Fig. 7 is a fragmentary cross sectional view as taken in the direction of arrows 7-7 in Fig. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Figs. 1, 2, and 3 illustrate respective stages of a preferred procedure for practice of the present invention with regard to fabrication of heat exchanger fins embodying the invention. The illustrated procedure comprises fabrication of the fins from a strip 10 of either steel, alloy or any other comparable material. The strip 10 is shown to be of a uniform width W.
In accordance with the invention, strip 10 is folded back over itself at locations along the length of the strip. Fig. 1 illustrates a succession of folds, and for convenience of description each of the folds to be discussed will be identified by a particular reference numeral.
The folding may be done by any suitable procedure. Three consecutive folds of interest for the purpose of description are identified by the reference numerals 12, 14, and 16. As a consequence of creating these three folds, there are four confronting portions of the strip which will also be discussed, and they are identified by the reference numerals 18, 20, 22 and 24. These four confronting portions are of substantially identical shapes, the disclosed shapes being rectangular.
As will become apparent from the ensuing description, portions 18 and 20 will cooperatively define one fin 26 in the final construction and portions 22 and 24 the immediately adjacent fin 28.
Fold 12 serves to integrally join the two confronting portions 20 and 22. Fold 14 integrally joins confronting portions 18 and 20 while fold 16 integrally joins confronting portions 22 and 24.
As can be appreciated from consideration of Fig. 1 the typical folding procedure will be such that each fold extends over a small radius for essentially 180° to join the corresponding two immediately contiguous confronting portions. In the disclosed preferred embodiment, each of the two fins 26 and 28 is intended to have an interior space through which a fluid medium can pass. A second fluid medium is intended to pass through the space between the two fins whereby heat exchange between the two media can take place through the fins.
As can be appreciated from consideration of Fig. 1 at this stage of the fabrication process, the two confronting portions which are to form one of the fins have unjoined margins 30 extending from fold 12 to the corresponding fold 14, 16 for the respective fins 26, 28. According to principles of the invention confronting margins 30 are joined together by any suitable means such as welding, brazing, soldering and the like.
Fig. 2 illustrates a typical construction at the conclusion of joining of the margins. As can be seen, the margins of the two confronting portions 22 and 24 have been joined as indicated by the reference numeral 32. The margins 30 of the portions 20 and 18 have not as yet been joined.
The procedure for joining the margins involves a certain pinching which, in explaining with reference to fin 28, extends into fold 16 such that the ends of fold 16 are somewhat pinched together as well. In other words the radius of curvature of fold 16 is maintained for substantially its full length, except immediately adjacent the margins.
The margins are joined from fold 16 substantially to fold 12. The exact procedure by which the margins are joined is not important and various ways of joining are contemplated. However, when the margins are joined near fold 12 there is a similar tendency to pinch the ends of that fold. Absent a further feature of the invention to be next described, this pinching of the ends of fold 12 has a tendency for creating problems in the construction.
The further feature of the present invention involves the deformation of fold 12 in such a way that the structural integrity of the fins is assured while at the same time the desired functional capability of the heat exchanger is attained, this being in the context of fabricating the fin structure from a single strip of material.
According to the preferred procedure both ends of fold 12 are deformed by displacing material from the ends of the fold more fully between the confronting portions of the adjoining fins. The displacement of material serves to strengthen the heat exchanger at the adjoining fold between the immediately adjacent fins, it serves to ensure proper spacing between the immediately adjacent fins, and it allows the margins to be joined substantially to the fold 12.
The preferred procedure for deforming the ends of fold 12 comprises displacing material inwardly more fully between the adjoining fins such that the end of each fold is deformed into a generally triangular shape at each end. These triangular shaped deformations are designated by the reference numerals 34. The construction in effect amounts to the triangles being canted in relation to fold 12. The apex of each triangle is identified by the reference numeral 36 and is seen to merge into the root of fold 12. The triangular surface is generally flat and comprises a free edge 38 opposite apex 36 with the free edge being disposed in generally perpendicular relationship to the planes of the fins. Reference is made to the fins as occupying planes and it will be appreciated that this is used in a general sense for convenience since the fins do occupy three dimensions.
The construction thus far described serves to define a shape for the interior space of each fin, much like a thin pillow, or pocket. In other words each fin has an interior space of a generally thin rectangular volume except along the margins and the folds where the edges are curved due to folding and joining. Each completed fin is therefore closed along three of its four sides, with the fourth side being open (reference numeral 39 in Fig. 3).
The deforming of the ends of the fold 12 to produce the triangular shapes 34 may be conducted by any conventional procedure. Moreover, the procedure can be conducted on a continuous basis by an automatic process so as to continually produce a succession of formed fins assuming a configuration like that shown in Fig. 3. Thus Fig. 3 constitutes the resultant heat exchange fin structure 40 formed from the material of strip 10. By considering the resultant construction of Fig. 3 relative to Figs. 1 and 2, it can be understood that the description given with reference to folds 12, 14, and 16 and the adjoining confronting portions constitutes a pattern which is repeated in the resultant construction which has more than two fins.
Although the foregoing description has been necessarily given in a certain order with reference to the illustrations of Figs. 1, 2, and 3, it will be appreciated that the actual sequence in which the various operations are conducted will- depend upon the particular procedure which is utilized.
Fig. 4 illustrates a further extension of the invention wherein additional parts of the heat exchanger are cooperatively associated with the fin structure 40.
A pair of members 42 are shown attached to fin structure 40 and these may be considered to be in the form of brackets or plates each of which has a main part 44 extending away from the heat exchange fin structure and a flange 46 disposed against the heat exchange fin structure. It can be seen that each flange 46 and the main part 44 are at an obtuse angle with respect to each other. The flange is disposed against and secured to the triangularly shaped surfaces 34 by any conventional means.
These members 42 can constitute side support pieces or mounts by way of example.
Fig. 5 is an enlarged view looking into the heat exchanger fins through openings 39 to see the interior spaces 48. It is possible to cooperatively associate a still further part of the heat exchange structure with the fin structure 40. This is shown in Figs. 6 and 7 wherein a further member 50 is disposed against structure 40 at openings 39 into interior spaces 48. Member 50 is of a corrugated form matching the pattern of the heat exchanger fins. As can be seen in Figs.6 and 7 the corrugations 52 run lengthwise of the openings 39, and they project at least partially into the fin interiors. By making the dimension across the additional member from top to bottom as viewed in Fig. 7 somewhat less than the distance between the apexes 36 at the ends of fold 12, the resulting construction defines an entrance 54 into the interior space 48 adjacent one end of fold 12 and an exit 56 at the opposite end. While given shapes have been shown for the additional parts Figs. 4, 6 and 7 associated with the fin structure, it will be appreciated that other shapes and forms may be used depending upon any given implementation of the invention.
Thus it has been shown that the invention provides a novel and unique way of efficiently fabricating finned heat exchange structure, particularly where the fins are to be provided with an interior space through which a fluid medium can pass. The invention is efficient in that the finned structure can be fabricated from a strip of material through particular procedures and it does not involve the use of additional parts except those other additional parts of the heat exchanger which may be joined to the fin structure such as those which have been already described.
While a preferred embodiment of the invention has been disclosed, it will be appreciated that principles are applicable to other embodiments.

Claims

1. The method of making fins of a finned heat exchanger comprising the steps of folding a strip back over itself at locations along the length of the strip such that integrally adjoining one of the folds on opposite sides thereof are a pair of confronting portions of the strip each of which in turn integrally joins by a further one of said folds with a further confronting portion of the strip, each of said pair of confronting portions and the corresponding further confronting portion comprising unjoined margins extending from the corresponding further fold to said one fold, joining said unjoined margins from said corresponding further folds substantially to said one fold, and deforming said one fold to displace material therefrom more fully between said pair of confronting portions which adjoin said one fold.

2. The method set forth in claim 1 in which the step of deforming said one fold comprises deforming at least one end of said one fold to displace material therefrom more fully between said pair of confronting portions at said at least one end of said one fold.

3. The method set forth in claim 2 in which the step of deforming at least one end of said one fold comprises deforming both ends of said one fold so as to displace material from both ends of said one fold more fully between said pair of confronting portions at both ends of said one fold.

4. The method set forth in claim 2 in which the step of deforming at least one end of said one fold comprises deforming said at least one end in such a way as to create a generally triangular shape of displaced material with the generally trangular shape having a free edge which is generally perpendicular to the immediately adjacent ones of said margins.

5. The method set forth in claim 1 in which the strip has a uniform width and the step of folding the strip back over itself comprises folding the strip along lines of folding which are parallel to the width of the strip so that said confronting portions are of generally rectangular shapes.

6. The method set forth in claim 1 in which the step of deforming said one fold comprises deforming said one fold so as to form a flattened surface at at least one end of said one fold and including the further step of disposing a further part of the heat exchanger against said surface and joining said further part to said surface.

7. The method set forth in claim 6 in which the step of deforming said one fold so as to form a flattened surface at least one end of said one fold comprises deforming said at least one end in such a way as to create a generally triangular shape of displaced material with the generally triangular shape having a free edge which is generally perpendicular to the immediately adjacent ones of said margins and wherein the step of disposing a further part of the heat exchanger against said surface and joining said further part to said surface comprises said further being a member having a main part and a flange which is at an obtuse angle to said main part and joining said flange and said triangular shaped surface.

8. The method set forth in claim 1 including the further step of then joining a further part of the heat exchanger to the formed fins.

9. The method set forth in claim 8 in which the steps of folding the strip back over itself and joining the unjoined margins is conducted in such a way that each of said pair of confronting portions and the corresponding further portion are formed to cooperatively define an interior space which is open immediately adjacent said one fold.

10. The method set forth in claim 9 including the further step of cooperatively associating a further part of the heat exchanger partially over the openings to the interior spaces of the fins so as to form an entrance to the interior of each fin adjacent one end of said one fold and an exit at the opposite end.

11. The method set forth in claim 9 in which said further part comprises corrugations and in which the further part is cooperatively associated with the fins such that corrugations project at least partially into the interiors of the two fins.

12. Heat exchanger fin structure comprising a strip folded back over itself at locations along the length of the strip such that a pair of immediately adjacent fins integrally adjoin via one of the folds on opposite sides thereof, and one or more deformations of said one fold comprising material displaced from said one fold more fully between said fins.

13. Heat exchanger fin structure as set forth in claim 12 in which the displaced material is from at least one of the ends of said one fold.

.4. Heat exchanger fin structure as set forth in claim 13 in which the displaced material is from both ends of said one fold.

15. Heat exchanger fin structure as set forth in claim 13 in which the displaced material qomprises a generally triangular shape having a free edge-which is generally perpendicular to the main extent of the fins.

16. Heat exchanger fin structure as set forth in claim 15 further including additional heat exchanger structure disposed against and joined to said triangular shaped displaced material.

17. Heat exchanger fin structure as set forth in claim 12 in which each of said fins is defined by two confronting portions of said strip wherein the two confronting portions of each fin integrally join along a corresponding other one of said folds, wherein each pair of confronting portions forming a fin have margins joined together from the corresponding other one of said folds substantially to said one fold, and wherein each pair of confronting portions forming a fin are spaced apart to define an interior space for the fin.

18. Heat exchanger fin structure as set forth in claim 17 wherein said fins are open to their interior spaces adjacent said one fold, and including further means disposed against the openings into the interiors of the fins to define an entrance and an exit for each fin's interior.

19. Heat exchanger fin structure as set forth in claim 18 in which said further means comprises a part having corrugations projecting at least partially into the interior spaces of said fins.