Mitsubishi Denki Kabushiki Kaisha

Kuen Yehliu

Keiichi Enoki

Hideaki Tani

Tadahiro Azuma

A device includes: downstream air-fuel ratio feedback control unit that performs feedback control of an upstream target air-fuel ratio so that a downstream air-fuel ratio detected by a downstream air-fuel ratio detecting unit coincides with a downstream target air-fuel ratio; a target air-fuel ratio varying unit that varies the upstream target air-fuel ratio at the time of diagnosing degradation of a ternary catalyst; and a catalyst degradation judging unit that judges catalyst degradation from the behavior of the downstream air-fuel ratio at the time of diagnosing degradation of the ternary catalyst. When diagnosing degradation of the ternary catalyst, the downstream air-fuel ratio feedback control unit is stopped or its control constant is set at a smaller value. Thus, when varying the air-fuel ratio for diagnosing catalyst degradation, interference between downstream air-fuel ratio feedback and upstream air-fuel ratio feedback is prevented and catalyst degradation is accurately diagnosed.

Control device for internal combustion engine

A control apparatus for an internal combustion engine can detect degradation of a three-way catalyst with high accuracy without causing deterioration in an exhaust. A pair of first and second air fuel ratio detectors are disposed in an exhaust system at locations upstream and downstream of the three-way catalyst for detecting a first and a second air fuel ratio of an exhaust gas. A target oxygen change amount calculator calculates a target oxygen change amount of the three-way catalyst, and an oxygen change amount calculator calculates an oxygen change amount of the three-way catalyst from an amount of exhaust gas passing through the three-way catalyst and the first air fuel ratio. An air fuel ratio operator inversely controls the air fuel ratio to a rich side and a lean side with a prescribed air fuel ratio width each time the oxygen change amount reaches a target oxygen change amount.

Growing community of inventors

Tokyo, Japan

Kuen Yehliu