US3521707A

US3521707A - Heat exchangers

Info

Publication number: US3521707A
Application number: US755077A
Authority: US
Inventors: Dennis Cockburn Brown
Original assignee: Associated Engineering Ltd
Current assignee: Associated Engineering Ltd
Priority date: 1967-09-13
Filing date: 1968-08-26
Publication date: 1970-07-28
Anticipated expiration: 1987-07-28
Also published as: DE1776042A1; SE380584B

Description

July 28, 1970 D. c. BROWN HEAT EXCHANGERS 2 Sheets-Sheet 1 Filed Aug. 26, 1968 July 28, 1970 D. c. BROWN 3,521,707

HEAT EXCHANGERS Filed Aug. 26, 1968 2 Sheets-Sheet 2 United States Patent 3,521,707 HEAT EXCHANGERS Dennis Cockbum Brown, Leamington Spa, England, as-

signor to Associated Engineering Limited, Leamington Spa, Warwickshire, England, a British company Filed Aug. 26, 1968, Ser. No. 755,077 Claims priority, application Great Britain, Sept. 13, 1967, 41,849/67; Apr. 19, 1968, 18,741/68 Int. Cl. F28f 1/14 US. Cl. 165-452 Claims ABSTRACT OF THE DISCLOSURE A heat exchanger, particularly intended as a radiator core for a liquid cooled internal combustion engine, has heat exchange surfaces formed as fins from metal foil. The fins are formed by areas of a strip of metal foil which is bonded to members of the heat exchanger at regions between said areas and the fins are inclined with respect to each other such that adjacent fins extending from either side of a region converge towards each other.

The present invention relates to heat exchangers, and more particularly to core constructions for the radiators of liquid cooled internal combustion engines.

Heat exchangers, for example the cores of radiators for liquid cooled internal combustion engines, generally comprise a plurality of passages for the liquid coolant which are constituted by a plurality of individual tubular passageways or tubes arranged in rows and extending between tube plates, forming part of end shells or tanks, into which the opposite ends of the tubes are secured. The tubes are provided with, or are in contact with, cooling surfaces such as fins, for dissipating heat trans ferred to the tubes from the liquid passing therethrough from one end tank to the other.

It is an object of the present invention to provide an improved heat exchanger core construction which may be made from a metal foil, that is to say sheet material having a thickness up to approximately 0.012".

According to the present invention, a heat exchanger comprises a series of members made from metal foil (as hereinbefore defined) which are spaced apart to permit the flow of a first fluid therebetween, each member being formed from one or more sheet-like metal foil elements which are assembled and bonded so as to define one or more passages through which a second fluid can flow, and wherein the space between adjacent members contains cooling surfaces in the form of fins extending generally transversely to said members and formed by areas of a strip of metal foil which is bonded to said adjacent members at regions between said areas, said regions comprising portions of said strip each having an area extending generally parallel to the adjacent surface of the member to which it is bonded, and said fins being inclined with respect to each other such that the adjacent fins extending from either side of a region converge towards each other.

According to a feature of the invention, the fins are so inclined that they converge into contact with each other, whereby the regions in contact with any member cover virtually the whole surface of that member, to which they are bonded. In this way, a highly efficient heat transfer is obtained between the walls of the members through which the second fluid flows and the fins over which the first fluid flows.

According to a further construction each of said regions comprises a series of mutually staggered portions, alternate portions being staggered in opposite directions with respect to the longitudinal extent of the fins. Preferably each portion is of generally rectangular form thereby 3,521,707 Patented July 28, 1970 ice producing a generally castellated appearance to the surface of the regions which are bonded to the surfaces of the members through which the second fluid flows. Each fin therefore comprises two series of alternating mutually disposed areas. Preferably also in this construction the fins are so inclined that they converge into contact with each other whereby the mutually staggered portions of successive regions interengage with each other to form a virtually continuous surface which is bonded to said members.

The components of the heat exchanger are preferably made from aluminium foil. It will be understood that the term aluminium includes alloys of aluminium.

The elements forming the heat exchanger may be bonded together in any desired fashion and advantageously may be bonded together by means of an adhesive. If desired, the elements may be made from a metal foil pre-coated with an adhesive. Alternatively, the elements, or at least some of the elements, may be bonded together by means of welding, for example electron beam welding, plasma arc welding or laser beam welding, or by vacuum brazing.

The surfaces of the fins may be provided with dimples, louvres or other means to increase their heat exchange relationship with a fluid flowing over them.

The opposite ends of the tubular passageways formed by the members may pass through apertured tube plates extending across the ends of the structure, with the end fins bonded to the surface of the tube plates.

The invention will now 'be further described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a side sectional view of a part of one embodiment of radiator core constructed in accordance with the present invention,

FIG. 2 is a cross-sectional view along the lines IIII in FIG. 1,

FIG. 3 is a fragmentary perspective view of part of one form of the fin structure,

FIGS. 4a and 4b are fragmentary perspective views of two further forms of tubular passageway.

FIG. 5 is a fragmentary perspective view of a stage in the manufacture of a further embodiment of fin structure,

FIG. 6 is a fragmentary perspective view of part of the completed fin structure, and

FIG. 7 is a side sectional view of a part of a radiator core employing the fin structure of FIG. 6.

Referring to FIGS. 1 and 2, there is shown a side view of a part of a radiator core consisting of a plurality of tubular passageways 1, arranged spaced apart side-byside and each formed from a pair of strip elements 2 of aluminium foil having a thickness of up to approximately 0.012", for example of about 0.005 inch. Each element is formed, for example by rolling the strip, to define a central channel provided with flanges 3 along its side edges. Pairs of elements are assembled together with the abutting flanges bonded to each other so as to define the liquid passageways 1.

Between the adjacent tubular passageways are located corrugated strips 4 of metal foil of which certain areas define fins 5 extending generally transversely to said members. Each strip is bonded to the surface of the elements '2 at the regions 6 between the fins, which regions extend generally parallel to the adjacent surface of the element to which it is bonded. The fins are inclined With respect to each other such that the adjacent fins extending from either side of a region 6 converge into contact at their other ends so that said regions 6 cover virtually the whole surface of the element 2 to which they are bonded. In this way, a highly efficient heat transfer from the walls of the passageways 1 to the fins 5 is obtained.

However for some applications it may be sufi'icient if the fins merely converge towards each other, but not into contact, whereby the adjacent regions 6 in contact with any element 2 are spaced apart to some extent.

The ends of tubular passageways 1 pass through apertures plunged in tube plates 8 which are formed from a thicker gauge aluminum sheet With the walls of the passageways bonded to the neck 7 of the apertures, and with the end most fins bonded to the adjacent surfaces of the tube plates. Core end plates 9 extend between the tube plates at the opposite lateral edges of the core, these core end plates also being formed from thicker gauge aluminium sheet and serving to protect the edges of the core structure against damage. The core end p ates are secured to the tube plates by flanges 10.

The various components of the radiator core described are advantageously assembled together by means of an adhesive which is preferably a heat-curable adhesive. The aluminium foil and sheet from which the core is formed may be pre-coated with adhesive, or alternately or additionally, adhesive may be applied to the mating surfaces of the components as they are assembled together.

FIG. 3 is a fragmentary perspective view of one of the corrugated fin structures with the corrugations partly opened out and showing louvres 11 which may be provided in the surface on the fins in order to increase the heat exchange efliciency.

FIG. 4a shows a modified construction for the tubular passageways comprising two

channel sections

12 and 14 of aluminium foil, each section being formed with a longer side flange 13 which is bent over to embrace the shorter side flange 17 of the other section of the passageway and then bonded thereto.

FIG. 4b shows a further construction of tubular passageway comprising two flat foil strips 15, bonded on opposite sides of spacers 16 of metal or plastic material, arranged between the edges of the strips.

The various components of the core may be readily formed by simple mechanical shaping and/or pressing operations which can be easily adapted to the continuous formation of the components for mass production purposes. In particular the core may be constructed by firstly forming sub-assemblies consisting of a corrugated fin structure 4 having a strip 2 bonded to each side thereof, and then arranging the sub-assemblies in a stack with the flanges 3 of adjacent elements 2 in abutting relationships and bonding the flanges together to form the passageways 1.

End tanks may be secured to the tube plates to complete the radiator structure and may be formed from metal, such as aluminium, or moulded from a plastics material.

Referring now to the embodiment of FIGS. and 6, the fin structure is made from aluminium foil having a thickness, for example, of about 0.004". As shown in FIG. 5, a strip of foil 21 is formed with a series of slits 22 and so folded transversely to the strip as to f rm a series of generally rectangular ribs 23 comprising mutually staggered portions 24 throughout the longitudinal extent of each rib, successive portions being staggered in opposite directions. The areas 25 will form the cooling fins and the regions 26 between said areas and formed by the mutually staggered portions 24 are the surfaces bonded to the member through which the second fluid flows, such as the passageways 1 of FIGS. 1 and 2. The mutually staggered portions 24 are of generally rectangular form so that the surface of the regions 26 have a castellated appearance, as shown.

FIG. 6 shows the finished fin structure when the strip formed as shown in FIG. 5 is compressed so that adjacent fins 25 extending from either side of a region 26 converge into contact at their other end. The compres-' sion of the formed strip also causes the castellated portions 24 of the adjacent regions 26 to interfit as shown at 27 to form a virtually continuous surface to be bonded t0 the other members of the heat exchanger, so that a highly eflicient heat transfer can be obtained.

By reason of the structure of this embodiment includ ing the slitting and folding of the strip to produce the mutually staggered portions, each fin surface throughout its longitudinal extent comprises two series of alternating mutually displaced areas which interfit with areas of the next adjacent fin to produce a louvre-like overall fin structure.

The bonding of the fins and other features of construction of the heat exchanger may be generally as described in relation to the previous embodiments.

It will of course be understood that, if desirable, the formed strip of FIG. 5 may only be compressed to an extent such that the fins 25 extending from either side of a region 26 do not converge into contact with each other, in which case the castellated portions 24 of the regions 26 only partially interengage with each other.

FIG. 7 shows part of a radiator core, similar to FIG. 1 but employing fin structures as in FIG. 6. The tubular liquid passageways are again shown at 1 and may be of any of the forms herein described. The fin structure is shown with the areas 25 defining the fins and the regions 26 bonded to the walls 2 of the passageways 1. The tube end plates are shown at 8 and the core end plates at 9; these two parts being bonded together at the flanges 10.

I claim:

1. A heat exchanger comprising:

a plurality of tubular member made from metal foil which are spaced apart to permit the flow of a first fluid therebetween,

each of said tubular members being formed from at least one sheet-like metal foil element which is assembled and bonded to form said tubular member through which a second fluid can flow,

said tubular members having flat wall portions defining the space between adjacent members,

cooling surfaces in the form of fins disposed in the space between adjacent ones of said members and extending generally transversely to the longitudinal axis of said members,

said fins being formed by areas of a strip of metal foil which is bonded to said adjacent members at regions between said areas,

said regions comprising flat portions of said strip each extending generally parallel to the adjacent flat wall portion of said tubular member to which it is bonded, and

said fins being inclined with respect to each other such that the adjacent fins extending from either side of a region converge towards each other.

2. A heat exchanger as claimed in claim 1 wherein the fins are so inclined that they converge into contact with each other, whereby the regions in contact with any member cover virtually the whole surface of that member to which they are bonded.

3. A heat exchanger as claimed in claim 1, wherein each of said regions comprises a series of mutually staggered portions, alternate portions being staggered in opposite directions with respect to the longitudinal extent of the fins.

4. A heat exchanger as claimed in claim 3, wherein each portion is of generally rectangular form thereby producing a generally castellated appearance to the surface of the regions which are bonded to the surfaces of the member through which the second fluid flows.

5. A heat exchanger as claimed in claim 3, wherein the fins are so inclined that they converge into contact with each other whereby the mutually staggered portions of successive regions interengage with each other to form a virtually continuous surface which is bonded to said members.

6. A heat exchanger as claimed in claim 1, wherein said metal foil is an aluminium foil.

7. A heat exchanger as claimed in claim 1, wherein the elements thereof are bonded together by means of an References Cited adhesive.

8. A heat exchanger as claimed in claim 7, wherein UNITED STATES PATENTS said elements are made from a metal foil with adhesive 3??? r-o--k- 51-62 5215 means serving as a bonding medium. 1 1 Z 0 WS 1 9. A heat exchanger as claimed in claim 1, wherein 5 $265,127 8/1966 Mlckol at -152 the surfaces of the fins are provided with means to increase their heat exchamg6 area ROBERT A. OLEARY, Primary Exammer 10. A heat exchanger as claimed in claim 1, wherein T. W. STREULE, Assistant Examiner the opposite ends of the tubular passageways formed by 10 the members pass through apertured tube plates extending across the ends of the structure with the end fins bonded to the surface of the tube plates.