| 摘要 |
PURPOSE:To prevent an occurrence of engine stall while a throttle valve being driven to close, by an arrangement such that a secondary air supplying means can be rendered inoperative for a preset time from a time immediately before a throttle valve opening means starts its throttle valve closing action at the latest to a time that the valve closing action is completed. CONSTITUTION:A control circuit 24 actuates electromagnetic valves 15, 21 to operate via driving circuits 22, 23 upon an ignition switch 27 being turned ON. Since a pressure difference in negative pressure chambers 9, 10 is disappeared when the electromagnetic valve 15 is actuated, a control valve 8 is rendered inoperative, and thereby preventing a flow of secondary air to a downstream of throttle valve 5 even when a manifold negative pressure is raised abruptly. Then, the throttle valve 5 is actuated to open upon a starter switch 28 being turned ON, the control circuit 24 verifies as to whether a cranking r.p.m. is reached and thereby rendering the throttle valve to close freely after the first preset time. A secondary air supplying means is rendered inoperative for a second preset time which terminates after the first preset time. |
