摘要 |
PURPOSE:To enhance the hydrocarbon purifying performance and simplify the post-processing of adsorbed hydrocarbons. CONSTITUTION:When the temp. of the engine cooling water is below a certain specified value, a three-way valve 51 is operated under a control of a controller 80 to put a branch exhaust passage 30 in communication with the main exhaust passage 13, and hydrocarbons in the exhaust gas are adsorbed to adsorptive catalyst 40. When the temp. of the engine cooling water rises over the specified level, the branch exhaust passage 30 is shut off from the main exhaust passage 13 by means of the three-way valve 51, and the adsorptive catalyst 40 is heated by a heater 60, and the adsorbed hydrocarbons are turned into harmless substance through oxidation at the adsorptive catalyst. |