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US 5,472,673 AGranted
Exhaust gas purification device for an engine
AssigneeToyota Jidosha Kabushiki Kaisha
InventorsMasato Goto, Satoshi Iguchi, Kenji Katoh, Tetsuro Kihara
Life of this patent
Estimating the term…
Abstract
An engine comprising an exhaust passage having therein a NO.sub.x absorbent which absorbs the NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent is lean and releases the absorbed NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent becomes the stoichiometric air-fuel ratio or rich. A sulphur trapping device for trapping SO.sub.x contained in the exhaust gas is arranged in the exhaust passage upstream of the NO.sub.x absorbent.
Claims8
An exhaust gas purification device for an engine comprising:
- an engine;
- an exhaust passage which extends from an upstream end which receives exhaust gas from the engine, to a downstream end from which exhaust gas is released;
- an NO.sub.x absorbent arranged in the exhaust passage, wherein the NO.sub.x absorbent absorbs NO.sub.x contained in the exhaust gas when a concentration of oxygen in the exhaust gas flowing into the NO.sub.x absorbent is above a predetermined oxygen concentration, and wherein said NO.sub.x absorbent releases the absorbed NO.sub.x when the concentration of oxygen in the exhaust gas flowing into said NO.sub.x absorbent is lower than the predetermined oxygen concentration;
- and
- sulphur trapping means arranged in the exhaust passage upstream of said NO.sub.x absorbent for trapping SO.sub.x contained in the exhaust gas, wherein the trapped SO.sub.x is not released from the sulphur trapping means when the concentration of oxygen in the exhaust gas flowing into said sulphur trapping means is lower than the predetermined oxygen concentration so that SO.sub.x is prevented from reaching and being absorbed into the NO.sub.x absorbent.
2 more elements
Dependencies are inferred from the claim text.