Supercharger control means for internal combustion engine

A supercharged internal combustion engine comprising working chamber means of which volume cyclically changes in response to a rotation of the engine to conduct engine operating strokes including an intake and compression strokes, an intake system for supplying intake gas to said working chamber means, said intake system including main intake passage means having one end connected with said working chamber means to have the intake gas therein taken into the working chamber means under a suction pressure prevailing in the working chamber means, main throttle valve means provided in said main intake passage means, auxiliary intake passage means having one end connected with the working chamber means, supercharging means provided in said auxiliary intake passage means for providing a supply of supercharging gas to said working chamber means, auxiliary throttle valve means provided in said auxiliary intake passage means downstream of said supercharging means, timing valve means provided in said auxiliary intake passage means downstream of said auxiliary throttle valve means, valve operating means for operating said timing valve means in response to the rotation of the engine, engine load sensing means for detecting engine load, valve timing control means for controlling opening timing of the timing valve means so that the timing valve means is opened at least in a beginning period of the compression stroke, said valve timing control means including means for controlling the opening timing so that the opening timing is advanced in response to a decrease in the engine load.