Engine exhaust gas purifying system

摘要

Exhaust gas is caused to flow through a bypass passage during an adsorption mode. At this time, an adsorbing member adsorbs harmful components, e.g. HC, of the exhaust gas. Also, exhaust gas is caused to flow through the bypass passage to thermally desorb the harmful component held at the adsorbing member during a desorption mode. A quantity of heat given from exhaust gas to the adsorbing member during the desorption mode is calculated based on an operation state of an engine. It is determined that the desorption of the harmful components has been finished when the quantity of heat given to the adsorbing member reaches a total quantity of heat required for totally desorbing the harmful components adsorbed by the adsorbing member.