US 9,810,132 B2
Catalyst deterioration diagnosis apparatus
Hiroyuki Kano, Tokyo (JP); and Shinsuke Koike, Tokyo (JP)
Assigned to SUBARU CORPORATION, Tokyo (JP)
Filed by FUJI JUKOGYO KABUSHIKI KAISHA, Tokyo (JP)
Filed on Feb. 23, 2016, as Appl. No. 15/50,794.
Claims priority of application No. 2015-037721 (JP), filed on Feb. 27, 2015.
Prior Publication US 2016/0251996 A1, Sep. 1, 2016
Int. Cl. F01N 11/00 (2006.01)
CPC F01N 11/007 (2013.01) [F01N 2550/02 (2013.01); F01N 2560/025 (2013.01); F01N 2900/0418 (2013.01); F01N 2900/1402 (2013.01); Y02T 10/47 (2013.01)] 3 Claims
OG exemplary drawing
 
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 configured to detect an air-fuel ratio of the exhaust gas being introduced to the catalyst converter;
a downstream side air-fuel ratio detector configured to detect an air-fuel ratio of the exhaust gas being discharged from the catalyst converter;
an air-fuel ratio variation integrator configured to calculate 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 configure to determine 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
the air-fuel ratio variation integrator is configured to hold 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 when the engine stops operating and 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 is configured to resume 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 when later the engine restarts and the diagnosis running condition is satisfied again, and
the air-fuel ratio variation integrator is configured to reset 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 when a remaining amount of fuel is equal to or less than a predetermined lower limit at an end of operation of the engine.