Patent ID: 7036568

Claim:
A heat exchanger comprising: a plurality of heat-exchanging plate members, each of which has a plurality of projection ribs to form inside fluid passages through which inside fluid flows; and a heat-exchanging core portion containing the plurality of heat-exchanging plate members, wherein each of the plurality of heat-exchanging plate members is disposed adjacent another of the plurality of heat-exchanging plate members, said heat-exchanging core portion having a space between adjacent disposed heat-exchanging plate members to which said plurality of projection ribs are exposed to disturb a flow of outside fluid in said space, wherein: each of said plurality of heat-exchanging plate members has fluid passage forming portions; each of the projection ribs has an elongated opening in a longitudinal direction thereof; the fluid passage forming portions are positioned in such a manner as to confront inner surfaces of the projection ribs which define the elongated openings; each of the fluid passage forming portions has a substantially flat wall which cooperates with a respective projection rib to define the inside fluid passage; each of the fluid passage forming portions has contact portions which are positioned at both sides of the flat wall and are connected to the inner surface of the respective projection rib; the contact portions protrude inside of the respective projection rib so as to be connected to the inner surface of the respective projection rib in such a manner that a stress is applied to the connection between the contact portions and the inner surface of the projection rib is a shearing stress; and said contact portion in each fluid passage forming portion has a convex shape protruding along said inner surface of the respective projection ribs.