The invention discloses an engine
exhaust manifold assembly. The front end mouth portion of each
exhaust manifold is extended and is mounted at intervals on an air inlet
flange, a three-way catalyst is cylindrical, the back end of each
exhaust manifold is gathered together and connected with the front end of the three-way catalyst through a horn-shaped transition tube, the inner
diameter of the horn-shaped transition tube is gradually increased from the front end to the back end, the air inlet
flange is a
casting part and is sleeved at the back end of the three-way catalyst, an included
angle alpha of 20-80 degrees is formed between the front end face and the back end face of the air inlet
flange, the inner
diameter of the air inlet flange is gradually decreased from the front end to the back end, the back end of the three-way catalyst is inserted into the front end mouth portion of the air inlet flange and is welded with the air inlet flange, and the back end mouth portion of the air inlet flange extends outwards to form a flange mounting plate. The engine exhaust manifold
assembly has the advantages of simple structure, low air discharging
back pressure, good engine dynamic property, small heat loss, high cold starting property and the like, and requirements of national five emission standards can be met.