PURPOSE: To maintain the number of revolution in the engine at the time of idling to the optimum value in such a way that a flow control valve whose opening rate is controlled by means of a step motor is installed on the path to bypass upstream and downstream of a throttle valve.
CONSTITUTION: A flow control valve device 8 which is installed on the surge tank 2 comprises a motor housing 10 to hold a step motor 9, a motor housing end plate 11, and valve housing 12. A valve chamber 15 is formed in the valve housing 12, and the valve chamber 15 is communicated through a bypass pipe 16 which is fixed in the valve housing 12 to the inside of an air intake pipe 3 in the upsteam of a throttle valve 4. On another hand, a valve seat 19 is inserted to an air efflux port 18 which is formed at a flange 14, and it cooperates with a valve body 36 that is installed at a valve shaft 20. And, the valve shaft 20 is controlled through a rotor 21 equipped with an inner cylinder 40 which is screwed with outer screw threads 29 by means of the step motor 9.
TANAKA SHINICHIROU
ITOU HIROSHI
