| 摘要 |
PURPOSE:To improve reliability of a device, by providing a flow control step motor in a bypass passage, detouring a throttle valve, and rotating said step motor at a relatively slow constant speed till the bypass passage is fully opened when a key switch is turned OFF. CONSTITUTION:Idle speed of an engine is controlled by opening an air outflow port 18 to a surge tank provided in an intake pipe and controlling a bypass flow of air guided to said outflow port 18 from a bypass pipe 16 arranged detouring a throttle valve in the intake pipe. Here a flow control valve device 8 is constituted so that a valve shaft 20, that is, valve body 36 can be axially moved through meshing of screws 47, 29 by turning a rotor 21 with operation of a step motor 9. When the idle speed is controled out of the prescribed speed, the step motor 9 is rotated at a prescribed speed, while at OFF time of a key switch, said motor 9 is rotated at a slower speed than said prescribed speed to fully open the valve body 36. |
