Title:
エンジンの排気系診断装置
Document Type and Number:
Japanese Patent JP4338586
Kind Code:
B2
Abstract:
The invention relates to a diagnostic device and method of an engine exhaust purifying system, which perform active control of an air-fuel ratio and can make diagnosis of air-fuel ratio sensors (81, 82), catalysts (70, 75), etc. in the engine exhaust purifying system with high accuracy and reliability while avoiding a worsening of exhaust emissions, an increase of revolution variations, etc. The diagnostic device comprises an exhaust air-fuel ratio control unit (100) for performing control to keep an air-fuel ratio of exhaust gas flowing into a main catalyst (75) near a stoichiometric ratio in accordance with outputs of downstream air-fuel ratio sensors (82), a rich/lean switching unit (102) for switching over an air-fuel ratio in each of the cylinder groups to be rich or lean, thereby making diagnosis of each downstream air-fuel ratio sensor (82), a response detecting unit (110) for detecting a response of the downstream air-fuel ratio sensor (82) when the rich/lean switching of the air-fuel ratio in each cylinder group is performed, and a downstream sensor deterioration determining unit (104) for determining a deterioration of the downstream air-fuel ratio sensor (82) based on the detected response.
Inventors:
Yoichi Iiboshi
Shinji Nakagawa
Toshio Hori
Yoshikuni Kurashima
Shinji Nakagawa
Toshio Hori
Yoshikuni Kurashima
Application Number:
JP2004155899A
Publication Date:
October 07, 2009
Filing Date:
May 26, 2004
Export Citation:
Assignee:
株式会社日立製作所
International Classes:
F02D41/14; F02D45/00; B01D53/94; F01N3/20; F01N3/24; F01N3/28; F02D41/04; F02D41/36
Domestic Patent References:
| JP7034933A | ||||
| JP7197837A | ||||
| JP2002256936A | ||||
| JP9033478A | ||||
| JP8338291A |
Attorney, Agent or Firm:
Yusuke Hiraki