| 摘要 |
A dynamic catalyst bed temperature Td is computed by taking the thermal capacity of an exhaust system (36,38,40) into consideration. Therefore, even when the operating condition of an engine (2) is in transition, it is possible to obtain a bed temperature that corresponds to an actual catalyst bed temperature at an exhaust purifying catalyst (38) in a state where no addition of fuel is being performed. When a steady-state catalyst bed temperature Ts, which determines the amount of addition of fuel, satisfies an inequality Td - Ts > Tjd, addition of fuel is excessive, which can excessively increase the catalyst bed temperature. Even if this is a case, addition of fuel is prohibited by setting a fuel addition limiting flag Fac to ON. Therefore, even if the operating condition of the engine (2) is in transition, the exhaust purifying catalyst (38) is not excessively heated. |
