Patent ID: 6220019
Filing Date: 2001-04-24
Classification: B01D,B60K,B60W,F01N,F02D,Y02T,Y10S

Abstract:
An exhaust gas purifying apparatus for an internal combustion engine, which is disposed in an exhaustion system of an internal combustion engine in which a driving force is assisted by an electric motor, comprising:nitrogen oxide purifying means for absorbing a nitrogen oxide in an exhaust gas in an exhaust gas-lean state in which an oxygen concentration of the exhaust gas is relatively high, and for reducing the absorbed nitrogen oxide in an exhaust gas-rich state in which the oxygen concentration of the exhaust gas is relatively low;reducing means for controlling an air-fuel ratio of an air-fuel mixture to be supplied to the engine, so as to make the exhaust gas be in the exhaust gas-rich state;engine stopping means for, provided that at least a throttle valve of the engine is substantially fully closed, stopping the engine; andcontrolling means for, when the air-fuel ratio of the air-fuel mixture is set to be on a lean side with respect to a theoretical air-fuel ratio immediately before a stop of the engine, activating said reducing means to reduce the absorbed nitrogen oxide in the exhaust gas-rich state immediately upon restart of said engine after the engine is stopped.