Patent ID: 6109024
Filing Date: 2000-08-29
Classification: F01N,F02B,F02D,Y02T

Abstract:
An exhaust gas purification device for an internal combustion engine capable of operating on lean air-fuel combustion, the engine being provided with a direct cylinder injection valve for injecting fuel directly into a cylinder thereof and an exhaust gas passage extending through which exhaust gas travels away from the cylinder, said device comprising:exhaust gas air-fuel ratio adjusting means for adjusting an air-fuel ratio of exhaust gas produced by lean air-fuel ratio combustion in the cylinder from a lean air-fuel ratio to a rich air-fuel ratio by injecting additional fuel into the cylinder from the direct cylinder injection valve during one of an expansion stroke and an exhaust stroke of the cylinder;NH.sub.3 conversion means disposed in the exhaust gas passage downstream of the cylinder wherein, when additional fuel is injected to the cylinder by the exhaust gas air-fuel ratio adjusting means, the exhaust gas air-fuel ratio adjusting means provides rich air-fuel ratio exhaust gas to the NH.sub.3 conversion means, the NH.sub.3 conversion means producing NH.sub.3 by converting at least a portion of NO.sub.x contained in the exhaust gas to NH.sub.3 ; andpurification means disposed in the exhaust gas passage downstream of the NH.sub.3 conversion means for purifying both NO.sub.x and NH.sub.3 included in the exhaust gas by reacting the NO.sub.x with the NH.sub.3.