| 摘要 |
PROBLEM TO BE SOLVED: To reinforce a tumble flow without increasing ventilation resistance, in an intake system for an engine. SOLUTION: The valve seat 31 of an intake valve 16 is pressed in the inlet part, fronting on a combustion chamber 14, of an intake port 12. The central axis of the inner peripheral surface 33 of the valve seat 31 is inclined along the flow passage of the intake port 12 based on the central axis of an outer peripheral surface 32. Since a flow of intake air introduced in the combustion chamber 14 through the valve seat 31 through the intake port 12 by opening of the intake valve 16 smoothly flows in the combustion chamber 14 along the inclining inner peripheral surface 33 of the valve seat 31, directivity of a flow of intake air is improved and a velocity of intake air flow is maintained at a high value and combustion efficiency is improved by reinforcing a tumble flow T. Since no throttle is situated at the intake port 12, ventilation resistance is prevented from increase.
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