COMBUSTION GAS PURIFIER AND INTERNAL COMBUSTION ENGINE

A combustion gas purifier, wherein a small capacity pre-catalytic device (34) is disposed just on the downstream side of an exhaust port (18) and a large capacity main catalytic device (35) is disposed just on the downstream side of the pre-catalytic device (34), the pre-catalytic device (34) comprises finely divided catalytic carriers (48) and a third stage heat exchanger (H3) formed by bending a heat exchanger tube (49) zigzag is disposed between the catalytic carriers (48), fourth stage and five stage heat exchangers (H4, H5) are disposed on the upstream side of the pre-catalytic device (34) in the exhaust gas flow direction and first and second heat exchangers (H1, H2) are disposed on the downstream side of the main catalytic device (35) in the exhaust gas flow direction, and water is flown through the first stage heat exchanger (H1) to fifth stage heat exchanger (H5) in the direction reverse to the exhaust gas flow direction so as to perform a heat exchange between the water and the exhaust gases, whereby a catalyst temperature can be controlled actively to an optimum temperature range without lowering the energy efficiency of an entire system.