The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 21, 2000
Filed:
Oct. 06, 1998
Yukihiro Yamashita, Kariya, JP;
Shigenori Isomura, Kariya, JP;
Denso Corporation, Kariya, JP;
Abstract
In an engine exhaust system, an NOx catalyst for occluding NOx in a state of the lean air-fuel ratio and reducing the occluded NOx in the state of the rich air-fuel ratio. A CPU sets a target air-fuel ratio of a mixture supplied to an engine to the lean side with respect to the stoichiometric air-fuel ratio for the lean mixture combustion. The CPU sets a rich time for a rich mixture combustion in accordance with the engine operating state and the NOx purification rate in the NOx catalyst. In this moment, the shortest rich time is set within a range in which a desired NOx purification rate by the NOx catalyst is obtained. A three-way catalyst may be arranged upstream of the NOx catalyst. The three-way catalyst carries only a noble metal such as platinum having no oxygen storing capability.