| 摘要 |
PURPOSE:To securely prevent the erroneous detection of engine stall due to a rotation error on a high speed side by cutting off a power transistor when the lowering quantity of engine speed gets larger than a set value which is varied in accordance with said engine speed. CONSTITUTION:In an engine control device 10, a hard/soft switchover circuit 13 is switched over to either of a hard ignition or a soft ignition by means of a switchover signal from a CPU 14. That is, when the lowering quantity of engine speed is larger than the number of revolutions for judging hard ignition switchover which is obtained by multiplying an engine speed calculated from a rotation angle sensor 1 by a factor and tending to engine stall, a hard ignition is set and a transistor 15 is cut off, thereby, preventing the heat generation of the power transistor 15 and an ignition coil 20. Thus, since the number of revolutions for judging hard ignition switchover is varied by the engine speed, the erroneous detection of engine stall due to a rotation error on a high speed side can be securely prevented.
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