| 摘要 |
The catalyst system for an exhaust from an internal combustion engine has at least two valve controlled exhaust outlet ports for each cylinder. A first catalyst bed (1) is adapted to interact selectively with the entire exhaust gas of the engine. A second catalyst bed (8) is disposed at a located closer to the engine exhaust than the first catalyst bed (1). Output of the second catalyst bed (8) is passed to the exhaust from said engine at a point prior to its input to the first catalyst bed (1). Inlet to the second catalyst bed (8) is from one of the exhaust outlet ports which is so controlled as to allow exhaust gas flow preferentially during a predetermined time. Other of the exhaust outlet ports of each cylinder are so controlled as to allow exhaust gas flow at other predetermined times directly to the first catalyst bed (1) along such a flow path as to avoid the second catalyst bed (8). The system allows rapid catalytic conversion of exhaust gases upon start up of the engine but prevents overheating and therefore deterioration of the initially used converter. <IMAGE> |
