| 摘要 |
When an engine rotation speed in an engine for working machine without a governor mechanism is increase-and-decrease-controlled by switching ignition timings at a predetermined rotation speed, the response delay of the engine rotation speed with respect to the throttle opening operation is suppressed. The engine rotation speeds for switching the ignition timings are set to 4000 rpm and 5000 rpm. When the throttle opening is increased, a first ignition timing is advanced stepwise to a second ignition timing at the engine rotation speed of 4000 rpm so as to be switched to a rotation control characteristic C30 for high speed rotation. When the throttle opening is decreased, the second ignition timing is retarded stepwise to the first ignition timing at the engine rotation speed of 5000 rpm so as to be switched to a rotation control characteristic C05 for low speed rotation. The switching timing of the rotation control characteristic is different between at increase and decrease of the throttle opening. The difference can be reduced to a small amount DeltaTH.
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