| 摘要 |
An electronic control device for an internal combustion engine 1 for controlling the air-fuel ratio of a mixture of air and fuel supplied to the engine 1 is provided. A purge passage 6 is provided between the engine 1 and a fuel tank 19 to supply evaporated fuel from the fuel tank 19 to the engine 1. Furthermore, a canister 18 is provided in the purge passage 6 to store the evaporated fuel, and a purge control valve 7 is placed between the canister 18 and the engine 1 to vary the amount of fuel vapor which is supplied to the engine 1. The control device controls the flow rate of the fuel vapor from the canister 18 to the engine 1 by controlling the length of time and the amount which the purge control valve 7 is opened. In order to accurately determine how long and to what degree to open the valve 7, the control device considers how long the purge control valve 7 has been closed immediately before it is opened. Furthermore, the control device may also take into account other operating conditions of the engine 1, such as the rotating speed of the engine 1, the position of the throttle valve 16, and the temperature of the intake air, when determining how long to open the purge control valve 7.
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