Speed reduction method for hand-carried engine-driven working machine

Abstract

A speed reduction method for a hand-carried engine-driven working machine is provided in which a speed reduction of an engine can be attained reliably and safely by preventing the occurrence of lean come-down phenomenon in such a state that the engine is operating in a practical revolution speed range. An acceleration is calculated based on a change in revolution speed, and when the acceleration becomes smaller than a predetermined threshold, an ignition timing is retarded by a desired amount based on a determination that the engine is being decelerated, and further, a fuel flow rate is also increased, whereby the decelerated state of the engine is maintained without fail, so that the occurrence of lean come-down phenomenon is prevented in the process of reducing the revolution speed of the engine.

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