| 摘要 |
PURPOSE:To improve purifying efficiency for exhaust gas by providing an exhaust passage on an upstream side of an exhaust purifying catalyzer with a bypass passage having an adsorbent to adsorb unburnt gas in the exhaust gas, and its inlet part with a change-over valve. CONSTITUTION:An exhaust passage 2 extending from an exhaust port of an engine body 1 is provided with a catalytic converter rhodium 3 on its midway, and said passage 2 on an upstream side of said rhodium 3 is composed of a main passage 2a and a bypass passage 4 which are arranged in parallel with each other. The bypass passage 4 is provided with an adsorbent 5 to adsorb unburnt gas in exhaust gas, and an upstream branch connection between said both passage 2, 4 with an electromagnetic change-over valve 6. A gamma-alumina activated carbon formed of granular activated carbons covered with porous alumina, for instance, is used as said adsorbent 5. When the temperature of the exhaust gas exceeds 80 deg.C and remains below the activating temperature (about 200 deg.C) of said rhodium 3, a control unit 9 switches said valve 6 to cause the exhaust gas to flow through the main passage 2a. |
