| 摘要 |
PURPOSE:To steer clear of a lowering of engine maximum power caused by exhaust recirculation as well as to prevent an increase of black smoke, etc., with the exhaust recirculation suspended in high load operation, by installing two suction control valves in a control system of an EGR valve. CONSTITUTION:An EGR valve 12 being intermediately installed between capillary tubes 14 and 16 which are interconnected to an exhaust manifold 10 and a suction tube 6 through, comprises a valve element 18 to be opened or closed by a diaphragm unit 20. This diaphragm unit 20 is to actuate the valve element 18 in accordance with the magnitude of negative pressure to be taken into its suction chamber 22 and have the negative pressure by a vacuum pump 32 introduced into the said suction chamber 22 through a capillary tube 34, etc., in design. In this case, a choke system 35, the 1st and 2nd suction control valves 37 and 59 are intermediately installed through the within of the capillary tube 34, etc. This 1st suction control valve 37 is to be made up so as to cause the negative pressure, which is proportionally decreased according to the amount of treadling accelerator, to be produced at port 43 and the 2nd suction control valve 59 is also to be made up so as to close when negative pressure is below the set value. |
