Method of controlling air-fuel ratio of internal- combustion engine

Abstract

Abstract PURPOSE:To improve drivability and emission performance by controlling an air-fuel ratio to bring it to the approximation of a theoretical air-fuel ratio when the deviation between engine speeds measured for certain intervals each is greater than the specified value and controlling it to be lean when the deviation is less than the value. CONSTITUTION:A controller 44 constituted of a microcomputer takes in the newest engine speed. Ne from a revolution angle sensor 42 for every one turn of a crankshaft, reads out an engine speed Ne' preceeding thereto by one turn from RAM 52 and has Ne stored in RAM 52 as Ne'. The controller finds the deviation DELTANe between Ne and Ne' and calculates the level DELTANe' of discriminating any transient condition by multiplying Ne by the standard constant of the transient condition. In case of DELTANe<DELTANe', mixture is controlled to have a lean air-fuel ratio so as to adversely affect the exhaust gas purifying performance and improve fuel consumption. In other case of DELTANe>DELTANe', exhibiting the transient period of variation in car speed, the fuel ratio is placed under feedback control to approach the theoretical value so that a car is driven with exhaust gas purified. Since the transient condition is discriminated definitely, drivability and emission performance may be improved.

Inventors

• 👤 Mitsuharu Taura
• 👤 田浦　光晴
• 👤 「たか」尾　光則
• 👤 Mitsunori Takao

Bibliographic Details