Document Type and Number:
Japanese Patent JP4225017
Kind Code:
B2
Abstract:
To correctly determine whether a amount of sulfur stored in NOXcatalyst should be reduced or not, while keeping good exhaust emission control action by the NOXcatalyst.
At two points with a time interval between them, a rich time purification ratios PER(1), PER(2), that are NOXpurification ratios of NOXcatalyst when an air-fuel ratio of inlet exhaust gas is switched to rich, and fuel consumptions SQF(1), (2) are detected to calculate a rich time purification ratio change rate DPE. A present rich time purification ratio PE is estimated based on the rich time purification ratio change rate DPE and a present fuel consumption SQF, and an accumulated amount of SOXis estimated based on the estimated present rich time purification ratio PE. When the accumulated amount of SOXis larger than a tolerance for SOX, an air-fuel ratio of exhaust gas flowing into the NOXcatalyst is temporarily switched to be rich so as to reduce the accumulated SOXin the NOXcatalyst.
COPYRIGHT: (C)2004,JPO
Inventors:
Akio Matsunaga
Masaaki Kobayashi
Kingo Suyama
Application Number:
JP2002261913A
Publication Date:
February 18, 2009
Filing Date:
September 06, 2002
Assignee:
TOYOTA JIDOSHA KABUSHIKI KAISHA
International Classes:
F01N3/20; F02M25/07; F01N3/08; F01N3/24; F01N3/28; F02D21/08; F02D41/04; F02D45/00
Domestic Patent References:
Attorney, Agent or Firm:
Takashi Ishida
Jun Tsuruta
Masaya Nishiyama
