| 摘要 |
<p>PURPOSE:To prevent the supercooling of a trap and enhance the trapping rate of particulates, by bypassing the trap to allow all or a large part of an exhaust gas to flow in a bypass passage when an engine is at deceleration and an exhaust gas temperature is not greater than a predetermined value. CONSTITUTION:A trap C for trapping particulates in an exhaust gas is provided in an exhaust passage B of an engine A. There are provided a passage D bypassing the trap C, means E for detecting a decelerating condition of the engine, and means F for detecting an exhaust gas temperature or an engine operational condition relating thereto. There is further provided a valve device G for permitting all or a large amount of the exhaust gas to flow in the bypass passage D when the detected exhaust gas temperature is not greater than a predetermined value and the engine is at deceleration, while permitting all of the exhaust gas to flow through the trap C under any operational conditions other than the above condition. Accordingly, supercooling and superheating of the trap C are prevented, and the trapping rate of the particulates is enhanced.</p> |
