| 摘要 |
PURPOSE:To enable to control the engine speed at the time of its idling operation to an aimed value, by controlling a switching means such that a vacuum chamber of a vacuum or negative-pressure controlling mechanism is communicated selectively with a vacuum source or an atmospheric pressure source at the time of idling operation of engine. CONSTITUTION:According to an idling operation controlling program of a control circuit 54, a throttle valve position signal 50 of a prescribed register is put into a CPU, and if it is judged from the signal 50 that the throttle valve is at its idling position, a solenoid valve 40 in a vacuum passage 44 is opened. Then, the actual speed N of a rotational angle sensor 56 is compared with an aimed speed Ne stored in a memory. In case that N is higher than Ne, duty-ratio control is performed to delay the ignition timing by increasing the time for driving a solenoid 302 of a switching valve 30 to displace a valve body 301 to the right and thereby increasing the amount of atmospheric air supplied from an air cleaner 16 to an actuator 20. In case that N is lower than Ne, on the other hand, the ignition timing is advanced by operating the valve 30 reversely. Thus, it is enabled to control the engine speed at the time of its idling operation correctly to an aimed value. |
