The present invention relates to a system for automatically controlling the idling speed of an internal combustion engine, comprising a valve for supplying an adjustable quantity of additional air and generally set so as to choke a duct connecting zones up- and downstream from the throttle valve controlled by the accelerator.
On known automatic idling control systems, said valve consists of an electrovalve, the setting of which is controlled by a signal as a function of the difference between required and actually detected engine speed, for the purpose of maintaining engine speed constantly within a given range under varying operating conditions.
A major drawback on such known control systems is that they fail to provide for fast adjustment response, the disadvantage of which is particularly felt when applied to electronic injection systems providing for highly accurate, high-speed overall control of the engine via an electronic control system which, depending on signals from various sensors (mainly engine speed/stroke and air intake pressure/temperature sensors), determines, for example, air density inside the manifold, and engine speed, and calculates, via interpolation on respective memorized maps, the stroke and timing for injecting fuel into the injectors, as well as the spark lead.