Exhaust gas purification device for an engine

Abstract

A NO.sub.x absorbent which absorbs NO.sub.x in exhaust gas when the air-fuel ratio of the exhaust gas is lean and releases absorbed NO.sub.x when the oxygen concentration of the exhaust gas is lowered, is disposed in an exhaust passage of an engine. When the amount of the NO.sub.x absorbed by the NO.sub.x absorbent is increased, the regenerating process of the NO.sub.x absorbent is performed by supplying a reducing agent to the NO.sub.x absorbent so that the NO.sub.x absorbed by the NO.sub.x absorbent is released and reduced by the reducing agent. Usually, to reduce the amount of the reducing agent required for the regenerating process, the inflowing exhaust gas into the NO.sub.x absorbent is shut off. In the present invention, even in the regenerating process of NO.sub.x absorbent, a small amount of the exhaust gas (carrier gas) is introduced to the NO.sub.x absorbent to carry the supplied reducing agent through the NO.sub.x absorbent to thereby reduce the amount of the reducing agent required for the regenerating process and to shorten the time required to complete the regenerating process.

Dependencies are inferred from the claim text.