PURPOSE: To improve the fuel consumption at the time of idling by specifying the upstream side opening position in the bypass passage detouring a throttle valve in the device in which superchargers actuated according to rotation speed respectively are arranged in primary and secondary side intake passages arranged in a row.
CONSTITUTION: The intake passage 3 of an engine 1 is branched to branch intake passages 3a and 3b at the downstream side of an air flow meter, and their downstream sides are joined at the upstream side of an intercooler 5. Blowers Cp and Cs of primary and secondary side turbosuperchargers 9 and 10 are correspondingly arranged to passages 3a and 3b. A throttle valve 6 is arranged in the passage 3 at the downstream side of the intercooler 5, and also the bypass passage 71 detouring the valve 6 is connected. And the upstream end 71b of the passage 71 is opened to the secondary side passage 3b at the direct upstream of the blower Cs of the supercharger 10, and the adjustment valve 72, controlled according to the number of revolution of an engine at the time of idling, is interposed in the course of the passage 71.
OKIMOTO HARUO
TAJIMA SEIJI
