| 摘要 |
PROBLEM TO BE SOLVED: To efficiently purify HC in exhaust gas and in transpired gas from a fuel tank by increasing the temperature of catalyst up to an activating temperature at an early time after a start of an engine. SOLUTION: An absorbent 5, an electrically heated oxidizing catalyst 6 and three-way catalyst 7 are arranged in an exhaust pipe 4 in the mentioned order from the upstream side. When the temperature of exhaust gas is low, HC in exhaust gas is adsorbed to the adsorbent 5. When the temperature of the exhaust gas becomes higher, HC released from the adsorbent 5 is purified by the electrically heated oxidizing catalyst 6. At this time, secondary air is fed into the exhaust pipe 4 from an air pump 13 through an atmospheric passage 8a in order to enhance the purifying performance of the electrically heated oxidizing catalyst 6. When HC is completely released from the adsorbent 5, the secondary air is fed into the exhaust pipe 4 from the pump 13 by way of a canister 14 so as to purify HC contained in transpired gas fed together with the secondary air and accumulated in the canister 14. |
