| 摘要 |
<p>PURPOSE:To improve the exhaust emission control rate and raise the temperature of an ONx purifying catalyst speedily, during the cold time when the engine temperature is low and a three-component catalyst does not effectively operate. CONSTITUTION:A bypass passage 3 which discharges exhaust gas, making a detour around an NOx purifying catalyst 1 and a three-component catalyst 4 which purifies the exhaust gas discharged through the bypass passage 3 are installed in an engine exhaust system, and when the air-fuel ratio is over a prescribed value or less than a prescribed value and the engine temperature is below a prescribed value, the exhaust gas is allowed to flow to the NOx purifying catalyst 1 side.</p> |
