PURPOSE: To improve a combustion condition in the case of low speed and low load operation at the time of cold operation of a engine.
CONSTITUTION: A throttle valve 12 is provided in an intake passage 2 in the downstream of a supercharger 5, and the intake passage 2 between the supercharger 5 and the throttle valve 12 is connected to a jet stream hole 8, provided in an internal wall surface of an intake port 7 of an engine 1, by a communication path 9. By throttling the throttle valve 12 by actuating the supercharger 5 at an engine cold time, a delivery pressure of the supercharger and its temperature at low speed time are increased. In this way, an intake air temperature of the engine is increased and supercharger delivery air of high temperature and high pressure from the jet stream hole 8 is also injected, and since large disturbance is generated in a mixture in a combustion chamber 1a, combustion in the case of low speed and low load operation is improved.
TANAKA MASAAKI
KATO YUICHI
