Patent ID: 8322408

Claim:
A heat exchanger which comprises a heat transfer tube and a plurality of fins arranged in an axial direction of the heat transfer tube and exchanges heat between fluid flowing through the heat transfer tube and air flowing between the fins, wherein a plurality of flat sheet fins which each are formed in the shape of a flat sheet and a plurality of corrugated sheet fins which each are formed in the shape of a corrugated sheet are provided as the fins, the flat sheet fins and the corrugated sheet fins are alternately arranged in the axial direction of the heat transfer tube, an amplitude direction of the waveform of the corrugated sheet fins is substantially parallel to an axial direction of the heat transfer tube, and a ridgeline direction of the waveform of the corrugated sheet fins is substantially orthogonal to a front surface and a back surface of the heat exchanger so as to correspond to an air passage direction, and each of the plurality of corrugated sheet fins includes a front edge located at one end of the waveform in the ridgeline direction and a back edge located at the other end of the waveform in the ridgeline direction, the front edge at least partially defining an inlet of the air passage and the back edge at least partially defining an outlet of the air passage, wherein the flat sheet fins and the corrugated sheet fins have through holes for inserting the heat transfer tubes therethrough, cylindrical first collars which are continuous with the peripheries of the through holes protrude from only the flat sheet fins and cylindrical second collars which are continuous with the peripheries of the through holes protrude from only the corrugated sheet fins, the second collars are engaged with the first collars, thereby bringing the outer circumferential surfaces of the second collars into close contact with the inner circumferential surfaces of the first collars, while the heat transfer tubes are engaged with the second collars, thereby bringing the inner circumferential surfaces of the second collars into close contact with the outer circumferential surfaces of the heat transfer tubes.