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1. (WO2014207854) INTERNAL-COMBUSTION-ENGINE DIAGNOSTIC DEVICE

Pub. No.:    WO/2014/207854    International Application No.:    PCT/JP2013/067570
Publication Date: Thu Jan 01 00:59:59 CET 2015 International Filing Date: Thu Jun 27 01:59:59 CEST 2013
IPC: F02D 41/22
F02D 45/00
Applicants: TOYOTA JIDOSHA KABUSHIKI KAISHA
トヨタ自動車株式会社
MIYAMOTO, Hiroshi
宮本 寛史
MIYOSHI, Yuji
三好 悠司
IWAZAKI, Yasushi
岩崎 靖志
KIDOKORO, Toru
木所 徹
AOKI, Keiichiro
青木 圭一郎
Inventors: MIYAMOTO, Hiroshi
宮本 寛史
MIYOSHI, Yuji
三好 悠司
IWAZAKI, Yasushi
岩崎 靖志
KIDOKORO, Toru
木所 徹
AOKI, Keiichiro
青木 圭一郎
Title: INTERNAL-COMBUSTION-ENGINE DIAGNOSTIC DEVICE
Abstract:
This internal combustion engine is equipped with an exhaust purification catalyst (20) and an air-fuel-ratio sensor (41) on the downstream side of the exhaust-purification catalyst, and executes a fuel-cut control for stopping the supply of fuel, and a post-recovery rich control for controlling, after completing the fuel-cut control, the exhaust air-fuel ratio so as to be a rich air-fuel ratio. On the basis of the output air-fuel ratio outputted from the air-fuel-ratio sensor, first air-fuel-ratio-change properties and second air-fuel-ratio-change properties are calculated at the times when, after completing the fuel-cut control, the output air-fuel ratio first passes through a first air-fuel-ratio region (X) and a second air-fuel-ratio region (Y) which differs therefrom. The diagnostic device determines the state of the air-fuel-ratio sensor to be normal, abnormal, or determination-pending on the basis of the first air-fuel-ratio-change properties, and when the state is determined to be unclear, determines the state of the air-fuel-ratio sensor to be normal or abnormal on the basis of the second air-fuel-ratio-change properties. As a result, it is possible to minimize the impact of changes to the state of the exhaust purification catalyst, and accurately diagnose a responsiveness-deterioration abnormality of the downstream-side air-fuel-ratio sensor.