CATALYTIC DETERIORATION DETECTING DEVICE FOR INTERNAL COMBUSTION ENGINE

Japanese Patent JP3264234

B2

PROBLEM TO BE SOLVED: To accurately detect catalyst deterioration regardless of engine operation condition.
SOLUTION: In the upstream exhaust passage of a three-way catalyst 20 of an internal combustion engine 1, air/fuel ratio sensor 13 is arranged and an O2 sensor 15 is arranged in the downstream. In a control circuit 10, engine air/fuel ratio is feedback controlled to target air/fuel ratio based on an output of the sensor 13, 15, and during feedback control execution, based on an output locus length of the sensor 13, 15 whether deterioration is provided or not in the catalyst 20 is discriminated. In the control circuit, from an engine suction pressure and rotational speed, in what diagnostic region of a plurality of diagnostic regions the present engine is operated is judged, and a deterioration decision value set in each diagnostic region is used, and from the output locus length of the sensor 13, 15, the existence of deterioration of the catalyst 20 is decided. By setting respectively suited deterioration decision value in each diagnostic region of a plurality of the diagnostic regions, accurate decision of deterioration is performed regardless of a difference between conditions of engine operation.

JPH02183138	TROUBLE DIAGNOSING APPARATUS FOR VEHICLE
JPS62500540	[Title of the Invention] A device which controls and supervises a process of a car of operation
WO/1998/044251	DIAGNOSTIC SYSTEM IN AN ENGINE MANAGEMENT SYSTEM

Noritake Mitsutani

JP28883997A

March 11, 2002

October 21, 1997

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TOYOTA JIDOSHA KABUSHIKI KAISHA

G01M15/04; F01N3/20; F02D41/14; F02D45/00; G01M15/00; (IPC1-7): F01N3/20; F02D41/14; F02D45/00; G01M15/00

JP7247830A
JP726944A
JP8100635A
JP8246854A
JP843335A
JP8303233A

Takashi Ishida (3 others)

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