Apparatus for controlling the rotational speed of an I.C. engine in an idling operation

摘要

Apparatus for controlling the rotational speed of an I.C. engine in an idling operation comprises a constant pressure valve, a solenoid valve, and a control signal generator. A constant vacuum pressure produced by the constant pressure valve is modified by atmospheric pressure by means of the solenoid valve which is actuated by a pulsating signal produced in the control signal generator. The pulse width of the pulsating signal is variable in accordance with a detected engine speed. The modified vacuum pressure is coupled to a chamber of a main valve of a conventional boost controlled deceleration device to control the amount of air-fuel mixture supplied to the intake manifold of the engine.