| 摘要 |
PURPOSE:To stabilize rotation of an engine at the time of starting, by controlling an idling-speed control valve by way of feedback control such that a target value of current corresponding to the duty ratio is supplied to said control valve at the time of ordinary operation of the engine, but controlling the control valve by a relatively large duty ratio by interrupting the above feedback control at the time of starting the engine. CONSTITUTION:An electromagnetic idling-speed control valve 16 is disposed in a by-pass passage 14 which is extended to by-pass a throttle valve 8 and to communicate the upstream side of the throttle valve 8 and a surge tank 12 disposed on the upstream side of the throttle valve 8 with each other. In controlling the idling speed of an engine by controlling the control valve 16 by an electronic control circuit 44, a current detector 17 is provided for detecting the mean current passed through a solenoid of the control valve 16. At the time of ordinary operation of the engine, the solenoid of the control valve 16 is feedback-controlled such that the mean value of the above current passed through the solenoid is rendered equal to the target value corresponding to the duty ratio detected from the operational conditions of the engine. At the time of starting the engine, on the other hand, the above feedback control is interrupted and the solenoid is controlled by a duty ratio larger than the above duty ratio. |
