| 摘要 |
PURPOSE:To continue an idling operation even upon occurrence of abnormality, by providing a fixed command value generating means for outputting a constant command value to a control valve located in a bypass passage in the case that the abnormality is generated in a computing device. CONSTITUTION:A control valve 30 is provided in a bypass passage 31 communicating an upstream side of a throttle valve 32 with a downstream side thereof in a suction passage of an internal combustion engine. A microcomputer 5 in an electronic control device 40 calculates a command value for the control valve 30 so that an engine speed 15 may coincide with a target idling speed set according to an engine cooling water temperature 14. In the event that abnormality is generated in computing device, a selector 55 is operated to allow an output signal from a fixed duty pulse generator 59 to be fed to a solenoid 16. Thus, even upon occurrence of abnormality in the computing device, an idling operation can be continued.
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