| 摘要 |
PURPOSE:To efficiently operate a ternary catalyst, by intermittently supplying secondary air to the upstream side of the catalyst. CONSTITUTION:A mixture higher than the theoretical air fuel ratio is supplied to an engine 11. Air is intermittently supplied from a secondary air feed pipe 15 to the upstream side of the ternary catalyst 14, which is installed in an exhaust pipe 13 and contains an oxygen adsorber which adsorbs oxygen when the air fuel ratio of the exhaust gas is lower than the theoretical air fuel ratio and releases the absorbed oxygen when the air fuel ratio of the exhaust gas is higher than the theoretical air fuel ratio. Thereby, the air fuel ratio of the exhaust gas is fluctuated up and down centering the theoretical air fuel ratio. As a result, it is not required to vary the air fuel ratio of the mixture for the engine, and the ternary catalyst is efficiently operated. |
