Patent ID: 6981369

Claim:
An exhaust gas cleaning apparatus for an engine comprising: a NOx trapping catalytic converter disposed in an exhaust passage of the engine to trap NOx from exhaust flowing from the engine; an intake air regulating device disposed in an air intake passage of the engine to control an intake air quantity of air flowing into the engine; and a control unit configured to control the intake air regulating device and a fuel injection timing in accordance with an operating condition of the engine, the control unit including a rich spike control section configured to selectively reduce an opening degree of the intake air regulating device to reduce an excess air ratio such that the NOx accumulated in the NOx trapping catalytic converter is desorbed, a cylinder intake air quantity determining section configured to determine a representative value of a cylinder intake air quantity, a fuel injection timing computing section configured to compute the fuel injection timing based on the operating condition of the engine, and a fuel injection timing adjusting section configured to adjust the fuel injection timing based on the representative value of the cylinder intake air quantity during rich spike control.