Exhaust gas purifying system for internal combustion engine

Abstract

An exhaust gas purifying system for a cylinder direct internal combustion engine having a fuel injector valve for directly injecting fuel into a combustion chamber of the engine. The exhaust gas purifying system comprises an adsorbent catalytic converter disposed in an exhaust gas passageway of the engine. The adsorbent catalytic converter including a catalytic element having an adsorption layer. The adsorption layer contains an adsorbent for adsorbing HC (hydrocarbons) of exhaust gas in a first temperature range and to release the adsorbed HC in a second temperature range which is high relative to the first temperature range, and a catalyst component for promoting reaction for oxidizing HC which is released from the adsorbent. A control unit is provided to be programmed to carry out (a) judging that a temperature of the adsorption layer has reaches a releasing level relating to the second temperature range, so as to make a first judgment result; (b) judging that a temperature of exhaust gas flown into the adsorbent catalytic converter will rise upon injection of an additional fuel from the fuel injector valve into the combustion chamber during a time period including an expansion stroke and an exhaust stroke of the engine, so as to make a second judgment result; and (c) causing the fuel injector valve to controllably inject the additional fuel during the time period including the expansion stroke and the exhaust stroke of the engine upon making both the first and second judgment results.