Patent ID: 7487589

Claim:
A method of making a heat exchanger, comprising: a tube, an internal fin or fins, a tube strengthener or strengtheners, a header, and a tube-to-header junction, the method including the steps of: forming an internal fin or fins; forming a tube strengthener or strengtheners of a section or sections on the fin or fins; stuffing the internal fin or fins and the tube strengthener or strengtheners into the tube; localizing the tube strengthener or strengtheners with the tube at the area of the tube-to-header junction; forming a header joint at the area of the tube-to-header junction comprising the tube, header and tube strengthener or strengtheners, such that the heat exchanger at the area of the tube and tube strengthener at the header joint provides increased strength or durability to the heat exchanger; and brazing the tube and header to form a brazed header joint of increased thermal durability; wherein the characteristics of the internal fin or fins are different from the characteristics-of the tube strengthener or strengtheners; and wherein the internal fin has end sections where the tube strengthener replaces at least one of the first or final fin end section.