| 摘要 |
<p>PURPOSE:To improve the heat insulation characteristics of a catalyst during deceleration wherein an exhaust gas temperature is reduced and to improve catalyst performance. CONSTITUTION:When an engine is in a deceleration state, an exhaust bypass valve 7 is opened, exhaust gas is caused to bypass instead of the flow of it through a catalyst 3, and exhaust gas the temperature of which is reduced owing to deceleration is prevented from the flow of it to the catalyst 3. Even when an engine is in a deceleration state, if a temperature equivalent to that of the catalyst 3 is below a current exhaust gas temperature, bypass operation of exhaust gas for bypassing the catalyst 3 is stopped and exhaust gas having temperature higher than that of the catalyst 3 is introduced to the catalyst 3.</p> |
