| 摘要 |
PURPOSE:To enable to control recirculation of exhaust gas exactly, by stopping recirculation of exhaust gas when the excess air factor becomes lower than a prescribed value, and recommencing it when the depth of accelerator pedal depression becomes a prescribed value smaller than the value of accelerator pedal depression at the time when recirculation of exhaust gas is stopped. CONSTITUTION:A control unit 100 consisting of a micro-computer or the like is furnished with the excess air factor lambda from an excess air factor sensor 101 and the depth Vr of accelerator pedal depression from an accelerator sensor 102. Recirculation of exhaust gas is started by opening an exhaust-gas recirculation control valve 12 by energizing a solenoid changeover valve 32 and introducing negative pressure corresponding to the engine load from a vacuum control valve 60 to the control valve 12. In the above arrangement, recirculation of exhaust gas is stopped by energizing the solenoid changeover valve 32 when the excess air factor lambda becomes lower than a prescribed value. On the other hand, when the depth Vr of accelerator pedal depression becomes a prescribed value smaller than the value of accelerator pedal depression at the time when recirculation of exhaust gas is stopped, recirculation of exhaust gas is recommenced by energizing the valve 32. Since, with such an arrangement, recirculation of exhaust gas is interrupted exactly at the time of high-load operation of an engine, it is enabled to prevent lack of intake air that is possibly caused by recirculation of exhaust gas and to prevent emission of a large amount of white and black smoke. |
