Power plants – Internal combustion engine with treatment or handling of... – Methods
Patent
1995-09-08
1998-05-05
Hart, Douglas
Power plants
Internal combustion engine with treatment or handling of...
Methods
60276, 60288, 60289, 422171, 4232137, F01N 320
Patent
active
057460523
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.
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Database WPI, Section Ch, Week 9432, Derwent Publications Ltd., London, GB; Class E19, AN 94-259675, XP002025404 & JP 06 190 246 (Idemitsu Kosan Co., Ltd.), Jul. 12, 1994.
Igarashi Kouhei
Itou Takaaki
Kinugasa Yukio
Takaoka Toshifumi
Yaegashi Takehisa
Hart Douglas
Toyota Jidosha & Kabushiki Kaisha
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