Patent ID: 7303004

Claim:
A heat exchanger adopting a four-pass structure, comprising: a plurality of tubes disposed so as to distribute a coolant along a top-bottom direction over two rows to the front and rear along the direction of airflow; a first upper tank portion communicating with the upper end of a group of tubes disposed in one of the tube rows; a second upper tank portion communicating with the upper end of a group of tubes disposed in the other tube row; a first lower tank portion communicating with the lower end of said group of tubes disposed in the one tube row; a second lower tank portion communicating with the lower end of said group of tubes disposed in said other tube row; a communicating passage that communicates between one end of said first upper tank portion and one end of said second upper tank portion; a partitioning member partitioning said first upper tank portion and said second upper tank portion at substantial centers thereof; an inflow port communicating with the other end of said first upper tank portion, through which coolant from an outside source flows in; and an outflow port communicating with the other end of said second upper tank portion, through which coolant flows out to the outside; wherein said inflow port has an opening area smaller than an opening area of said outflow port; wherein a center of the opening area of said inflow port is located at a position higher than a center of the opening area of said outflow port; wherein the opening area of said inflow port is within a range of 25˜65 mm 2 ; wherein an end plate is fixed onto an end of said first upper tank portion and an end of said second upper tank portion; and wherein said inflow port and said outflow port are located at an outside of said end plate so as to open outside of said heat exchanger.