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:
Mar. 23, 1999
Filed:
Sep. 08, 1997
Toyota Jidosha Kabushiki Kaisha, Aichi-ken, JP;
Abstract
An exhaust gas purifying device, for an engine performing a lean operation and having an EGR system capable of controlling an EGR ratio, comprises a NO.sub.X catalyst arranged in the exhaust passage capable of selectively reducing NO.sub.X in the inflowing exhaust gas, in the oxidizing atmosphere including a reducing agent, and a reducing agent injector arranged in the exhaust passage of the engine for secondarily supplying a reducing agent to the exhaust passage upstream of the NO.sub.X catalyst. The EGR system has an EGR passage connecting the exhaust passage and the intake passage of the engine, an EGR control valve arranged in the EGR passage, and an intake air control valve arranged in the intake passage upstream of an inlet of the EGR passage. The openings of the EGR control valve and the intake air control valve are controlled to control the temperature of the exhaust gas to make the temperature of the NO.sub.X catalyst within the optimum temperature range or equal to the optimum temperature. The amount of the reducing agent injected by the reducing agent injector is made smaller as the EGR ratio becomes higher.