Intake system in internal combustion engine

Abstract

An intake system adapted to be used in combination with an internal combustion engine having a main combustion chamber and a preliminary or subcombustion chamber equipped with an ignition plug. There is provided an intake cylinder having a venturi portion which allows the passing of the total amount of air being fed to both combustion chambers and a throttle valve controlling the amount of air being fed to respective combustion chambers. The intake cylinder is divided into a main intake passage and sub-intake passage, both of which lead to both combustion chambers, respectively. A metering orifice is provided in the sub-intake passage, so that a ratio in amount, of air passing through respective intake passages may be maintained at a given value. In respective intake passages, there are provided fuel discharge values, to which are connected fuel passages leading from a single fuel pressure controlling valve for use in providing fuel pressure commensurate with the negative pressure in the venturi portion. By the provision of the metering orifices in respective fuel passages, a ratio in flow rate, of fuel being introduced to respective fuel discharge valves is maintained at a given value. Thus, there is provided an intake system in which a ratio in flow rate, of mixture charges being fed to the main combustion chamber and the sub-combustion chamber, as well as a ratio in air-fuel-ratio, of mixture charges being fed thereto are maintained constant.