초록 ▼

A control device of a lean-burn engine has an electronic control unit. Upon start of switching from stoichiometric driving to lean driving, the control unit (10) derives, from a map, a target pressure (P0) and a basic opening degree (D0) of an idling speed control valve, serving as an air bypass val

A control device of a lean-burn engine has an electronic control unit. Upon start of switching from stoichiometric driving to lean driving, the control unit (10) derives, from a map, a target pressure (P0) and a basic opening degree (D0) of an idling speed control valve, serving as an air bypass valve, based on the throttle opening degree (TPS) and the engine rotation speed (Ne) at the start of the switching. The control unit supplies driving pulses (N) of a number corresponding to the basic opening degree (D0) to a stepper motor (32) of the idling speed control valve. Then, the control unit supplies the stepper motor with driving pulses of a number corresponding to an opening degree correction amount (D1) which in turn corresponds to a deviation between the target intake pressure (P0) and an actual intake pressure (PB), to thereby suppress a change in the torque at the time of switching between the rich driving, including the stoichiometric driving, and the lean driving of the lean-burn engine.

대표청구항 ▼

[ We claim:] [1.] A control device for a lean-burn engine, comprising:load state detecting means for detecting a load state of the engine;fuel supply means for supplying fuel to the engine;intake air amount adjusting means for adjusting an amount of intake air supplied to the engine; andcontrol mean

[ We claim:] [1.] A control device for a lean-burn engine, comprising:load state detecting means for detecting a load state of the engine;fuel supply means for supplying fuel to the engine;intake air amount adjusting means for adjusting an amount of intake air supplied to the engine; andcontrol means for controlling said intake air amount adjusting means according to the engine load state detected by said load state detecting means, so as to cause that change in the load state which permits a difference between output torques of the engine before and after switching to be reduced or canceled, when the switching is made from driving with a first air-fuel ratio which is set equal to a theoretical air-fuel ratio or on a fuel-rich side with respect thereto to driving with a second air-fuel ratio which is set on a fuel-lean side with respect to the theoretical air-fuel ratio, whereinsaid intake air amount adjusting means includes an intake flow rate control valve provided in an intake passage for introducing the intake air into a combustion chamber of the engine,said control means includes target air-fuel ratio setting means for setting a target air-fuel ratio according to a driving state of the engine, and fuel amount setting means for setting a fuel amount to realize the target air-fuel ratio thus set;said fuel supply means supplies the fuel to the engine in accordance with the fuel amount set by said fuel amount setting means; andsaid target air-fuel ratio setting means includes follow-up changing means for successive iterative changing the air-fuel ratio to follow a change in an actual intake air amount at a time of switching from the driving with the first air-fuel ratio to the driving with the second air-fuel ratio.