To prevent exhaust of HC by an ignition lag of an exhaust re- combustor 21 for early activating a catalyst, and to avoid adverse influence by desorption of the adsorbed HC.
The exhaust re-combustor 21 is arranged on the upstream side of a catalyst device 23 of an exhaust passage 14 of an internal combustion engine 1, and an HC adsorbent 18 for adsorbing HC is interposed on the upstream side of the exhaust re-combustor. A secondary air pump 20 has an upstream side air introducing part 27 and a downstream side air introducing part 29, and is controlled by opening-closing valves 28 and 30. An engine control unit 26 burns gas again by adding secondary air by enriching the air-fuel ratio of the internal combustion engine 1 via a fuel injection valve 8. The secondary air is introduced from the downstream side of the HC adsorbent 18 up to actually starting combustion, and is switched to introduce the secondary air from the upstream side after starting the combustion. The separation of the HC is promoted by the passing of the secondary air.
OKADA KEIJI
KANETOSHI KAZUHIKO
TSUCHIDA HIROBUMI
