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. 05, 1998
Filed:
Sep. 08, 1995
Yukio Kinugasa, Susono, JP;
Kouhei Igarashi, Susono, JP;
Takaaki Itou, Mishima, JP;
Takehisa Yaegashi, Mishima, JP;
Toshifumi Takaoka, Susono, JP;
Toyota Jidosha Kabushiki Kaisha, Aichi, JP;
Abstract
In the present invention, the exhaust gas from the engine is divided into a first and a second branch exhaust passages after it passes through a three-way reducing and oxidizing catalyst, and the two branch exhaust passages merge into an exhaust gas outlet passage. In the first branch exhaust passage, an oxidizing catalyst is disposed, and in the exhaust gas outlet passage, a denitrating and oxidizing catalyst is disposed. NO.sub.x in the exhaust gas from the engine is all converted to N.sub.2 and NH.sub.3 by the three-way reducing and oxidizing catalyst and a part of the NH.sub.3 generated by the three-way catalyst flows into the first branch exhaust passage and is converted to NO.sub.x again by the oxidizing catalyst. The amount of NO.sub.x produced by the oxidizing catalyst and the amount of NO.sub.x flowing through the second branch exhaust passage is determined by the flow distribution ratio of the first and the second branch exhaust passages. In this invention, the flow ratio is determined in such a manner that the amount of the NO.sub.x produced by the oxidizing catalyst and the amount of the NH.sub.3 passing through the second branch exhaust passage are stoichiometric to produce N.sub.2 and H.sub.2 O. Therefore, when these exhaust gases flow into the denitrating and oxidizing catalyst after they mix with each other in the exhaust gas outlet passage, all the NO.sub.x and the NH.sub.3 are converted to N.sub.2 and H.sub.2 O by the denitrating and oxidizing catalyst without producing any surplus NO.sub.x or NH.sub.3.