Power plants – Internal combustion engine with treatment or handling of... – Material from exhaust structure fed to engine intake
Patent
1994-05-31
1995-09-12
Hart, Douglas
Power plants
Internal combustion engine with treatment or handling of...
Material from exhaust structure fed to engine intake
60285, 60289, F01N 320, F02M 2506, F02N 300
Patent
active
054488877
ABSTRACT:
An exhaust gas purification device of the present invention includes a three-way reducing and oxidizing catalyst disposed on an exhaust passage of an engine, and an NO.sub.x absorbent which absorbs NO.sub.x in the exhaust gas when the air-fuel ratio of the exhaust gas is lean and releases absorbed NO.sub.x when the air-fuel ratio of the exhaust gas is rich; the engine in the present invention is controlled in most of its operating region in such a manner that the operating air-fuel ratio of the engine oscillates between a rich air-fuel ratio and a lean air-fuel ratio about a center value of a stoichiometric air-fuel ratio; when the operating air-fuel ratio of the engine becomes lean, the ability of the three-way catalyst for reducing NO.sub.x in the exhaust gas becomes low, and a part of NO.sub.x in the exhaust gas passes through the three-way catalyst, and, since the air-fuel ratio of the exhaust gas is lean, this NO.sub.x is absorbed in the NO.sub.x absorbent located downstream of the three-way catalyst; when the operating air-fuel ratio of the engine becomes rich, the ability of the three-way catalyst for oxidizing HC and CO in the exhaust gas becomes low, and a part of HC and CO in the exhaust gas passes through the three-day catalyst; since the air-fuel ratio of the exhaust gas is rich, absorbed NO.sub.x is released from the NO.sub.x absorbent and this NO.sub.x is reduced as HC and CO passes through the three-way catalyst; therefore, the pollutants such as HC, CO, NO.sub.x are almost completely removed.
REFERENCES:
patent: 5201802 (1993-04-01), Hirota
patent: 5209061 (1993-05-01), Takeshima
patent: 5271223 (1993-12-01), Hoshi
patent: 5331809 (1994-07-01), Takeshima et al.
NO Removal by Absorption into BA.sub.O -CuO Binary Oxides (J. Chem Soc. Chem Commun, pp. 1165-1166).
Formation and Decomposition of BaCuO.sub.2.5 Prepared from a Mixture of Nitrates (Journal of solid state chemistry pp. 176-179).
NO Removal by Absorption into Ba-Cu-O Binary Oxides (Catalyst vol. 33 No. 2 pp. 87-89).
Hart Douglas
Toyota Jidosha & Kabushiki Kaisha
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