Vacuum control valve

摘要

A vacuum modulating chamber of a vacuum control valve is communicated with a diaphragm chamber of a EGR valve for controlling an amount of exhaust gas to be recirculated into combustion chambers of an engine, so that a modulated negative pressure is applied thereto. The chamber is provided with a diaphragm deflected responding to the negative pressure in the chamber. The vacuum control valve is further provided with a cam member and a spring which urges the diaphragm in one direction so as to change a value at which the pressure in the vacuum modulating chamber is controlled. A push rod is movably held by a cam follower and another spring is provided for urging the push rod in the above direction. The spring force of the other spring is applied to the diaphragm, when a rotational angle of the cam member exceeds a predetermined angle, so that the negative pressure is changed rapidly.