Control device for internal combustion engine

Details Control device for internal combustion engine Control device for internal combustion engine

2007-11-13

2007-11-13

Tran, Binh Q. (Department: 3748)

Power plants

Internal combustion engine with treatment or handling of...

Having sensor or indicator of malfunction, unsafeness, or...

C060S274000, C060S276000, C060S285000, C701S103000

Reexamination Certificate

active

11326403

ABSTRACT:
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.

REFERENCES:
patent: 5579637 (1996-12-01), Yamashita et al.
patent: 5735120 (1998-04-01), Nagai
patent: 5851376 (1998-12-01), Nishioka et al.
patent: 6594987 (2003-07-01), Uranishi
patent: 6751950 (2004-06-01), Ikemoto et al.
patent: 6761024 (2004-07-01), Uchida
patent: 11-270332 (1999-10-01), None

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