| 摘要 |
An exhaust gas cleaning apparatus for an engine has a NOx trapping catalytic converter and a control unit for controlling an intake air throttle valve and a fuel injection timing in accordance with an operating condition of the engine. The opening degree of the intake air throttle valve is reduced to accomplish rich spike control. The fuel injection timing is adjusted according to the boost pressure that develops downstream of the intake air throttle valve during rich spike control. Since the combustion tends to degrade when the boost pressure changes during rich spike control, the fuel injection timing is advanced more as the boost pressure becomes larger. This advancement of the injection timing compensates for the combustion degradation and prevents the occurrence of torque fluctuations when the opening degree of the throttle valve is adjusted during the shift to rich spike control to improve the engine operating performance.
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