| 摘要 |
PURPOSE:To secure safety while a stepping motor is not excited by connecting a control valve as a rotary type flow control valve to the shaft of a stepping motor, and providing a stopper for stopping the valve body in a position where the valve body is closed up, and providing a return spring for rotating the valve body in its closing direction. CONSTITUTION:When a valve body 16 is rotated clockwise through about 90 degrees with a control valve 5 full open, a throttling piece 18 blocks an outlet port 15 and an abutting piece 22 collides with a stopper 23. In accordance with the number of pulse signals of an exiting current sent from an electronic control device 6 to a stepping motor 4, the area of the passage of the outlet port 15 is varied by the throttling piece 18 to control the amount of air so as to maintain the idling speed of an engine at a predetermined value. In the event that the exiting current is cut off because of trouble with the control device 6 and the stepping motor 4 as the control valve 5 is opened, the valve body 16 is rotated clockwise by a return spring 21 having both ends stuck to the stopper 23 and the valve body 16 so that the throttling piece 18 blocks the outlet port 15. Therefore, only the air of a throttle valve 2 is supplied to the engine and so the speed of the engine is not heightened. |
