Air-fuel ratio control device of internal combustion engine

Abstract

Abstract PURPOSE:To prevent production of CO and HC components resulting from temporary evaporation of fuel adhered to the inner wall of a suction pipe, by a method wherein, when a sudden change in a negative pressure during shifting of an engine from a high load state to a low load state is detected, an air-fuel ratio is controlled to the lean side for a given time. CONSTITUTION:During running of an engine, in a control circuit 28, based on outputs from a water temperature sensor 36 and a throttle sensor 34, it is decided whether an engine is in an air-fuel ratio feedback control condition. When decision is YES, an output from a negative pressure switch 40, detecting sudden return control of a throttle valve 4, is inputted. When the negative switch 40 is turned ON, an air-fuel ratio control valve 14, located in air incoming passages 21 and 22, is forced into a full opening state, a maximum amount of air is introduced to a carbretter through air incoming passages 17 and 18, and an air-fuel ratio is controlled to a value on the maximum limit lean side. Further, when a cooling water temperature exceeds a given value, for example, 60 deg.C and the number of revolutions of an engine is below a given value, for example, 2,000rpm, an electromagnetic valve 48 is released, and the negative pressure switch 40 is brought into an inoperative state.

Inventors

• 👤 Nobuki Uchitani
• 👤 内谷　信喜
• 👤 Tatsuyoshi Kanbara
• 👤 蒲原　辰義
• 👤 Kouichi Satoya
• 👤 里屋　浩一
• 👤 Kenichi Nomura
• 👤 野村　憲一

Bibliographic Details