Catalyst deterioration diagnosis apparatus

Patent metadata

Field	Value
Publication number	US-2016251996-A1
Application number	US-201615050794-A
Country	US
Kind code	A1
Filing date	Feb 23, 2016
Priority date	Feb 27, 2015
Publication date	Sep 1, 2016
Grant date	—

Abstract

A catalyst deterioration diagnosis apparatus includes an upstream side air-fuel ratio detector, a downstream side air-fuel ratio detector, an air-fuel ratio variation integrator that integrates the output variations of the respective air-fuel ratio detectors when a diagnosis running condition is satisfied, and a determiner that determines catalyst deterioration when the output variation integrated value of the upstream side air-fuel ratio detector exceeds a predetermined integration ending threshold, and further when a ratio between the output variation integrated value of the two detectors exceeds a predetermined determination threshold. The air-fuel ratio variation integrator holds the integrated values when the diagnosis running condition becomes unsatisfied before the integrated value of the upstream side air-fuel ratio detector reaches the integration ending threshold. The air-fuel ratio variation integrator resumes the integration using the held values as initial values when the diagnosis running condition is satisfied later again.

First claim

1 . A catalyst deterioration diagnosis apparatus that diagnoses deterioration of a catalyst converter to which exhaust gas of an engine is introduced, the apparatus comprising:
an upstream side air-fuel ratio detector that detects an air-fuel ratio of the exhaust gas being introduced to the catalyst converter; a downstream side air-fuel ratio detector that detects an air-fuel ratio of the exhaust gas being discharged from the catalyst converter; an air-fuel ratio variation integrator that calculates an output variation integrated value of the upstream side air-fuel ratio detector and an output variation integrated value of the downstream side air-fuel ratio detector when a predetermined diagnosis running condition is satisfied; and a determiner that determines catalyst deterioration of the catalyst converter when the output variation integrated value of the upstream side air-fuel ratio detector exceeds a predetermined integration ending threshold, and further when a ratio of the output variation integrated value of the downstream side air-fuel ratio detector to the output variation integrated value of the upstream side air-fuel ratio detector exceeds a predetermined determination threshold wherein, when the diagnosis running condition becomes unsatisfied before the output variation integrated value of the upstream side air-fuel ratio detector reaches the integration ending threshold, the air-fuel ratio variation integrator holds the current output variation integrated value of the upstream side air-fuel ratio detector and the current output variation integrated value of the downstream side air-fuel ratio detector and, when the diagnosis running condition is satisfied later again, the air-fuel ratio variation integrator resumes integration of the output variation integrated values using the held output variation integrated value of the upstream side air-fuel ratio detector and the held output variation integrated value of the downstream side air-fuel ratio detector as initial values.

2 . The catalyst deterioration diagnosis apparatus according to claim 1 ,
wherein, when the engine stops operating before the output variation integrated value of the upstream side air-fuel ratio detector reaches the integration ending threshold, the air-fuel ratio variation integrator holds the current output variation integrated value of the upstream side air-fuel ratio detector and the current output variation integrated value of the downstream side air-fuel ratio detector and, when the engine restarts and the diagnosis running condition is satisfied later, the air-fuel ratio variation integrator resumes integration of the output variation integrated values using the held output variation integrated value of the upstream side air-fuel ratio detector and the held output variation integrated value of the downstream side air-fuel ratio detector as initial values.

3 . The catalyst deterioration diagnosis apparatus according to claim 2 ,
wherein, when a remaining amount of fuel is equal to or less than a predetermined lower limit at an end of operation of the engine, the air-fuel ratio variation integrator resets the output variation integrated value of the upstream side air-fuel ratio detector and the output variation integrated value of the downstream side air-fuel ratio detector.

4 . The catalyst deterioration diagnosis apparatus according to claim 1 , further comprising: a misfire detector that detects a misfire of the engine,
wherein, when a frequency of a misfire detected by the misfire detector is equal to or more than a predetermined misfire determination threshold, the air-fuel ratio variation integrator resets the output variation integrated value of the upstream side air-fuel ratio detector and the output variation integrated value of the downstream side air-fuel ratio detector.

5 . The catalyst deterioration diagnosis apparatus according to claim 2 , further comprising: a misfire detector that detects a misfire of the engine,
wherein, when a frequency of a misfire detected by the misfire detector is equal to or more than a predetermined misfire determination threshold, the air-fuel ratio variation integrator resets the output variation integrated value of the upstream side air-fuel ratio detector and the output variation integrated value of the downstream side air-fuel ratio detector.

6 . The catalyst deterioration diagnosis apparatus according to claim 3 , further comprising: a misfire detector that detects a misfire of the engine,
wherein, when a frequency of a misfire detected by the misfire detector is equal to or more than a predetermined misfire determination threshold, the air-fuel ratio variation integrator resets the output variation integrated value of the upstream side air-fuel ratio detector and the output variation integrated value of the downstream side air-fuel ratio detector.

Assignees

• Fuji Heavy Ind Ltd

Inventors

• Kano Hiroyuki
• Koike Shinsuke

Classifications

• F01N2550/02

  Catalytic activity of catalytic converters · CPC title

• F01N11/007 Primary

  the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus · CPC title

• Y02T10/40

  Engine management systems · CPC title

• F01N2560/025

  for measuring or detecting O2, e.g. lambda sensors · CPC title

• F01N3/20

  specially adapted for catalytic conversion (F01N3/22 takes precedence) · CPC title