Automotive oil cooler

Claim 1

A heat exchanger comprising: a plurality of heat exchanger units, each unit including a first plate and a second plate, each having a through hole in a central portion thereof and an inlet hole and a communication hole in a peripheral portion thereof, a ring positioned so as to be axially aligned with said communication hole and between said first and second plates so as to be in contact with the inner surfaces thereof, and a collar, disposed around said through hole between said first plate and said second plate such that one surface of said collar is in contact with an inner surface of said first plate and the other surface of said collar is in contact with an inner surface of said second plate, said collar being formed in a generally circular shape and having a cut portion, said first and second plates being assembled together with said ring and collar therebetween with corresponding holes of said plates being axially aligned, the cut portion of said collar being positioned with respect to said through hole to permit the introduction of a first fluid through said inlet hole into said through hole, said plurality of units being stacked with corresponding holes thereof being axially aligned, the first and second plates being shaped such that when said units are stacked a first space is defined between respective first and second plates of each unit through which a first fluid can flow and a second space is defined between adjacent units through which a second fluid can flow; a case for enclosing said plural heat exchanging units and said second space; a through bolt, having a flange portion, fitted into said through hole, said flange portion of said through bolt being axially aligned with said collar.