| 摘要 |
PROBLEM TO BE SOLVED: To prevent unburned HC from increasing owing to fuel adherence to a combustion chamber wall when an intake valve 9 is set to extremely low lift by a variable valve mechanism. SOLUTION: A lift amount of the intake valve 9 is variably controlled corresponding to the operating condition owing to the variable valve mechanism. A seat surface 21 corresponding to a seal surface 26 of a valve head 9a is formed with an upstream side conical surface 22. The seat surface 21 reaches the end of the valve seat 20, and directly opens to the end. The angle of tiltβof an angular part at the angular part 23 of an opening periphery is given much. In an extremely low lift, an intake air flows along the seat surface 21. The flow is peeled off the wall surface at the angular part 23. Therefore, the flow along a combustion chamber recessed wall 3 is lessened, and the adherence of the fuel and increase of the unburned HC are suppressed. COPYRIGHT: (C)2004,JPO
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