Air/fuel ratio control apparatus in an internal combustion engine

Abstract

An air/fuel ratio control apparatus for a fuel injection type internal combustion engine is able to prevent an air/fuel mixture supplied to the engine from becoming excessively lean even immediately after engine decelerations and thus provide an optimum air/fuel ratio at all times during engine operation. An engine operating parameter sensor such as a pressure sensor, a flow meter, etc., periodically senses an engine operating parameter such as the intake pressure in an intake manifold, the flow rate of intake air sucked into the engine, and the like. A deceleration sensor senses the beginning of engine deceleration. An engine control unit including a microprocessor calculates, from the output signal of the engine operating parameter sensor, a change in the engine operating parameter between two consecutive points in time, and it further calculates a corrected amount of injection fuel supplied to the engine on the basis of the change in the engine operating parameter thus obtained. The control unit controls the fuel injector such that the fuel injector can supply the corrected amount of fuel to the engine during a predetermined length of time from the beginning of engine deceleration. In addition, the length of time, during which the fuel injector can supply the corrected amount of fuel to the engine, or the corrected amount of injection fuel, can be increased in accordance with the decreasing engine temperature.

Dependencies are inferred from the claim text.