| 摘要 |
PURPOSE:To prevent a sudden change in an air-fuel ratio from occurring, by having an air throttle valve fully closed at time of specified low speed of an engine and/or at time of specified low opening of a throttle valve, in case of a device which sets up common fuel injection valves at the upstream of a throttle valve and installs the air throttle valve at the upstream side. CONSTITUTION:During drive of an engine 1, each output signal out of a throttle valve opening sensor 8, a cooling water temperature sensor 9 and an engine speed sensor 10 is inputted into an engine control unit 5, and an air throttle valve 7 is controlled for opening or closing according to the engine driving state judged from these signals. That is to say, when the engine 1 is not in a high speed state and it is in a low water temperature state, a pressure selector valve 22 is excited, leading the atmosphere into a vacuum chamber 20a of a diaphragm device 20, and the air throttle valve 7 is closed. And, even in case of being not in a low water temperature state, and at time of being in a low speed state as well as even at time of a low throttle opening state in a medium speed state, the air throttle valve 7 is controlled so as to be closed. In a driving state other than that, the air throttle valve 7 is controlled according to Venturi negative pressure.
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