Heat exchanger and a method and apparatus for the manufacture thereof

Claim 1

A method of attaching at least one fluid conducting metal tube to a plurality of heat dissipating metal fins, comprising the steps of: providing a plurality of heat dissipating fins; providing at least one oval or oblong shaped collar on each of said fins, said collars having openings having oval or oblong initial cross-sections through said fins; providing at least one metal tube having two ends and a generally oval or oblong outer cross section, said tube further having first similarly shaped wall portions at opposite ends of a major axis thereof and second similarly shaped wall portions at opposite ends of a minor axis thereof, and said tube having an outer cross-section slightly smaller than said initial cross-section of said openings; fitting said tube inside said openings of said fins; and attaching said tube to said fins by merely introducing an expansion means into one of said ends of said tube and moving said means through said tube to said other end thereof for progressively expanding said tube so as to progressively bring said first and second wall portions into contact with said collar and for further progressively expanding said tube and said collars to an extend such that said collars and said tube reach a condition in which said tube walls are stretched plastically to an outer cross-section slightly greater than said initial cross-section of said openings, and said collars are expanded elastically, further by providing at least one elongated spacer for supporting said second wall portions within said collars, said spacer substantially having a breadth corresponding to a distance between said second wall portions at a preselected location thereof and in the plastically stretched condition of said tube, and further by introducing said spacer into said tube at said preselected location and at said one end of said tube by moving said spacer directly with or behind said expansion means into said tube for preventing a shrinkback of said tube after plastical stretching thereof, and by terminating said process by leaving said spacer within said tube.

Claim 2

A method of attaching at least one fluid conducting metal tube to a plurality of heat dissipating metal fins, comprising the steps of: providing a plurality of heat dissipating fins; providing at least one oval or oblong shaped collar on each of said fins, said collars having openings having oval or oblong initial cross-sections through said fins; providing at least one metal tube having two ends and a generally oval or oblong outer cross section, said tube further having first similarly shaped wall portions at opposite ends of a major axis thereof and second similarly shaped wall portions at opposite ends of a minor axis thereof, and said tube having an outer cross-section slightly smaller than said initial cross-section of said openings; fitting said tube inside said openings of said fins; and attaching said tube to said fins by merely introducing an expansion means into one of said ends of said tube and moving said means through said tube to said other end thereof for progressively expanding said tube so as to progressively bring said first and second wall portions into contact with said collar and for further progressively expanding said tube and said collars to an extend such that said collars and said tube reach a condition in which said tube walls are stretched plastically to an outer cross-section slightly greater than said initial cross-section of said openings, and said collars are expanded elastically, further by providing at least one elongated spacer for supporting said second wall portions within said collars, said spacer substantially having a breadth corresponding to a distance between said second wall portions at a preselected location thereof and in the plastically stretched condition of said tube, and further by introducing said spacer into said tube at said preselected location and at said one end of said tube by moving said spacer directly with or behind said expansion means into said tube for preventing a shrinkback of said tube after plastical stretching thereof, and by terminating said process by leaving said spacer within said tube.

Claim 4

A method of attaching at least one fluid conducting metal tube to plurality of heat dissipating fins, comprising: providing a plurality of heat dissiptating fins; providing at leeast one oval or oblong shaped collar on each of said fins, said collars having openings having initial oval or oblong cross-sections through said fins; providing at least one metal tube, said tube having a longitudinal axis, two ends and a generally oval or oblong outer cross-section which is slightly smaller than said initial cross-section of said openings, and said tube comprising first wall portions at opposite ends of a major axis thereof, second wall portions at opposite ends of a minor axis thereof, and at least one inwardly directed flute in at least one of said wall portions, said flute substantially extending parallel to the longitudinal axis of said tube such that the tube has a circumference slightly greater than said openings; fitting said tube inside said openings of said fins; and attaching said tube to said fins by introducing an expansion tool into one of said ends of said tube and moving said tool through said tube to said other end thereof for progressively expanding said tube at its whole cross-section by pressing out said flute so as to bring said first and second wall portions into contact with said collars and for further expanding said tube and said collars by fully pressing out said flute to an extent such that said collars and said tube reach a condition in which said tube has a similarly shaped but slightly greater cross-section than said initial cross-section of said openings and so that said collars are deformed elastically, but without substantially stretching said tube walls, and terminating said process as all of said collars are in said elastically defomed condition.

Claim 5

A method of attaching at least one fluid conducting metal tube to plurality of heat dissipating fins, comprising: providing a plurality of heat dissiptating fins; providing at leeast one oval or oblong shaped collar on each of said fins, said collars having openings having initial oval or oblong cross-sections through said fins; providing at least one metal tube, said tube having a longitudinal axis, two ends and a generally oval or oblong outer cross-section which is slightly smaller than said initial cross-section of said openings, and said tube comprising first wall portions at opposite ends of a major axis thereof, second wall portions at opposite ends of a minor axis thereof, and at least one inwardly directed flute in at least one of said wall portions, said flute substantially extending parallel to the longitudinal axis of said tube such that the tube has a circumference slightly greater than said openings; fitting said tube inside said openings of said fins; and attaching said tube to said fins by introducing an expansion tool into one of said ends of said tube and moving said tool through said tube to said other end thereof for progressively expanding said tube at its whole cross-section by pressing out said flute so as to bring said first and second wall portions into contact with said collars and for further expanding said tube and said collars by fully pressing out said flute to an extent such that said collars and said tube reach a condition in which said tube has a similarly shaped but slightly greater cross-section than said initial cross-section of said openings and so that said collars are deformed elastically, but without substantially stretching said tube walls, and terminating said process as all of said collars are in said elastically defomed condition.