Internal combustion engine with supercharger

Claim 1

A fuel supply system for an internal combustion engine having at least one combustion chamber, which system comprises, in combination: a supercharger; a fuel intake passage means communicating at one end with a source of air through said supercharger and at the opposite end with the combustion chamber, a portion of said fuel intake passage means between said supercharger and the combustion chamber having a partition wall formed therein for defining first and second intake passages; an exhaust manifold leading from the combustion chamber to the atmosphere for discharge of exhaust gases emitted from the engine; primary and secondary throttle valves operatively housed within said first and second intake passages, respectively, for regulating the flow of air towards the combustion chamber, said primary throttle valve being adapted to be controlled by an acceleration pedal; means for biasing said secondary throttle valve to assume a closed position to substantially close said second intake passage; means, responsive to the pressure inside a portion of said fuel intake passage means at a position downstream of at least one of said primary and secondary throttle valves and upstream of the combustion chamber with respect to the direction of flow of air towards the combustion chamber, for opening said secondary throttle valve against said biasing means when the pressure attains a value at least as great as a predetermined value, such that opening of said secondary throttle valve gradually increases with increases in the pressure; and a fuel injecting nozzle for supplying fuel to the combustion chamber in admixture with the air fed through said intake passage means in a controlled air-fuel mixing ratio.