| 摘要 |
PROBLEM TO BE SOLVED: To provide a four-cycle engine for an outboard engine prevented from overspeed while minimizing rotational fluctuation. SOLUTION: In this four-cycle engine 10 for the outboard engine, intake- exhaust camshafts 33 disposed parallel with a vertically disposed crankshaft 12 are rotationally driven by the crankshaft 12, and at least the intake camshaft 33 is provided with a VVT(variable valve timing mechanism) 40 for changing the opening/closing timing of at least an intake valve 22. When engine speed exceeds a set value, the opening/closing timing of at least the intake valve 22 is changed by the VVT 40. Since the opening/closing timing of at least the intake valve 22 is thus changed by the VVT 40 instead of a conventional fuel cut-off during overspeed where the engine speed exceeds the set value, the ovespeed of the engine 10 can be prevented by lowering engine output, torque and rotation while minimizing the rotational fluctuation of the engine 10.
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