| 摘要 |
PURPOSE:To enable EGR amount to be corrected when a trapper is choked in an exhaust system equipped with a particulate trapper by providing an exhaust throttle valve in the exhaust system to control exhaust pressure in response to the choked condition of said trapper. CONSTITUTION:When a trapper in a particulate trapper 24 interposed between exhaust pipes 22, 23 is not choked, exhaust pressure in an exhaust takeout portion 22 is low and an exhaust throttle valve 25 is under the inoperative condition. Thus, EGR valve 9 is then controlled by control negative pressure generated by a negative pressure controlling valve 19. On the other hand, when said trapper 24 is choked to raise the exhaust pressure, a diaphragm 28 in an exhaust throttle valve control 26 is pressed against a spring 30 to open the exhaust throttle valve 25. Then the exhaust pressure at the upstream side of the valve 25 is reduced and the difference between said exhaust pressure and pressure in an intake manifold 12 becomes small so that EGR amount is reduced even if the opening area of EGR path 13 is same. |
