Heat exchanger

Abstract

Heat exchangers (H4, H3, H2, H1) are sequentially disposed within an exhaust port (18), within a pre-catalytic device (34), and on the downstream of a main catalytic device (35); the exhaust port (18), the pre-catalytic device (34), and the main catalytic device (35) being provided in an exhaust passage (33) of an internal combustion engine. With regard to the heat transfer surface densities (heat transfer area/volume) of these heat exchangers (H4, H3, H2, H1), that of the heat exchanger (H4) on the upstream side of the exhaust passage (33) is the lowest, and that of the heat exchanger (H1) on the downstream side is the highest. The heat transfer surface density becomes low in a section on the upstream side of the exhaust passage (33) where the temperature of the exhaust gas is high, and the heat transfer surface density becomes high in a section on the downstream side of the exhaust passage (33) where the temperature of the exhaust gas becomes low, thereby maintaining a uniform heat transfer performance across all of the heat exchangers (H4, H3, H2, H1).

Dependencies are inferred from the claim text.