Patent ID: 6918432

Claim:
A heat exchanger comprising: a tube in which fluid flows, the cross section of which is formed flat to define a major axis and a minor axis; and a fin for facilitating heat exchange between air and fluid, provided on a planar face of an outer surface of the tube, a portion of the fin being cut and raised so that the portion is formed into a louver, wherein a dimension of the fin parallel to the direction of the major axis of the tube is not more than an outer diameter of the tube in the direction of the major axis, a reinforcing portion, the shape of which is different from that of the louver, for enhancing the rigidity of the fin is provided in the fin on the upstream end and the downstream end of the fin in a direction of an air current, the louver being disposed between the reinforcing portion on the upstream end of the fin and the reinforcing portion on the downstream end of the fin; the length of the reinforcement portion perpendicular to the direction of the air current is generally equal to the cutting length of the louver; the reinforcing portion is composed by plastically deforming a portion of the fin into a wave-shape; and the reinforcing portion is formed over a majority of the width of the fin perpendicular to the direction of the air current.