| 摘要 |
PURPOSE:To enable an engine speed to be accurately estimated even when the first speed detector causes a trouble, by providing the second speed detector which estimates the engine speed from a pulsation of pressure in an intake and exhaust pipe. CONSTITUTION:The speed of an engine 1, when it is normal, is detected by the first speed detector 2, and its detecting signal is input to an injection control arithmetic part 4. The first speed detector 2, when it causes a trouble due to some cause, is switched to the second speed detector 3 by a selector circuit 21. And detecting a pulsation of pressure in an exhaust pipe 6 by a pulsation detector 7 and estimating the speed of the engine 1 through an engine speed converter circuit 8, the second speed detector 3 inputs a signal, corresponding to this speed, to the injection control arithmetic part 4. Accordingly, even when the speed detector 2 causes a trouble, fuel injection of a fuel injection device main unit 5 is continuously controlled.
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