| 摘要 |
PURPOSE:To prevent the exhaustion of HC into the atmosphere and the deterioration of acceleration performance caused by the rising of backing pressure by shutting off the by-path, in which exhaust gas flows only when the temperature of the gas is low, based on the signal relating to the sudden change of the operation condition of an engine. CONSTITUTION:A by-path 9, in which an adsorption device 10 comprising activated carbon is included, is provided and is in parallel with the air exhaust path in the down stream of catalysts 6 and 7. Exhaust gas is made to flow through the by-path 9 only when the temperature of the exhaust gas is the specified value or less by controlling the closing of a by-path valve 13 by means of a control unit 19. The control unit 19 controls the opening of the by-path valve 13 based on the signal relating to the sudden change of engine operation condition and shut off the flow of the exhaust gas passing through the by-path 9 by controlling the closing of a shutter valve 14. This constitution can prevent the HC adsorbing to the adsorption device 10 from being exhaust into atmosphere. In addition, the deterioration of acceleration performance caused by the lowering of exhaust resistance and the rising of backing pressure can be prevented. |
