Air-fuel ratio control device in internal-combustion engine

Abstract

Abstract PURPOSE:To enhance the purifying capacity of a catalyst to reduce the discharge amount of NOx, by carrying out the feed-back control of the air-fuel ratio upon steady state operation of an engine to obtain the stoichiometric air-fuel ratio, and as well, by controlling the air-fuel ratio to the rich side upon transient operation of the engine. CONSTITUTION:In a control circuit 10, upon engine operation, subtraction is at first made between the present value An and a previous value An-1 of rotational speed data Ne which are obtained from an rotating angle sensor 7, and the thus obtained value is compared with a predetermined value X. If An-An-1<=X the steady state condition is discriminated to carry out the normal air-fuel ratio feed-back control so that the skip amount R for the increment of fuel is set to, for example, 3%, and the fuel injection disabling time Tv of a fuel injection valve is set to, for example, 20ms. Meanwhile if An-An-1>X, the transient (acceleration) zone is discriminated to carry out the rich side fuel-air ratio control, the above-mentioned skip amount R is set to be large, for example, to 5% and the fuel injection disabling time to be long, for example 60ms.

Inventors

• 👤 Tamotsu Ogita
• 👤 荻田　保

Bibliographic Details