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:
May. 07, 2002
Filed:
Jun. 12, 2000
Yutaka Takaku, Mito, JP;
Shigeru Kawamoto, Hitachi, JP;
Yoshihisa Fujii, Hitachinaka, JP;
Shinji Nakagawa, Hitachinaka, JP;
Toshio Ishii, Mito, JP;
Minoru Ohsuga, Hitachinaka, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
An exhaust gas cleaning system for an engine capable of judging the amount of trapped NO and the oxygen storage capacity of an NO trap agent and which can diagnose the deterioration of the NO trap agent. The NO trap is arranged in an exhaust gas passage and the air-fuel ratio of the exhaust gas is temporally changed from a lean air-fuel ratio to the stoichiometric air-fuel ratio or a rich air-fuel ratio with a predetermined cycle. The NO trapping occurs by absorbing or adsorbing NO in the exhaust gas when an air-fuel ratio of the exhaust gas is a lean air-fuel ratio and by releasing or reducing NO when the air-fuel ratio is a rich air-fuel ratio. The amount of trapped NO is judged from the oxygen concentration and the oxygen concentration in the exhaust gas is detected in the exhaust gas passage in the downstream side of the NO trap and determined by taking the oxygen storage capacity when the air-fuel ratio of the exhaust gas changes to the stoichiometric air-fuel ratio or the rich air-fuel ratio.