| 摘要 |
PROBLEM TO BE SOLVED: To reduce fuel consumption at partial load in particular by providing a device for changing the position of an exhaust valve lift curve relatively to a crank angle, providing the flow cross section of an exhaust passage so as to retreat against a combustion chamber, and arranging a chamfering part extending on one side of the flow cross section on a combustion chamber land. SOLUTION: As a device for changing the position of a valve lift curve relatively to a crank angle, for example, it is constituted so that both camshafts of a mutiple valve type engine are synchronously adjusted. In addition, at least one flow passage cross section 15 of an exhaust passage 8 is arranged so as to retreat against a combustion chamber, and a passage-like chamfering part 17 is formed in the connected range to a combustion chamber land 3 on one side of the flow passage cross section 15. The maximum length of the chamfering part 17 in the radial direction against the flow passage cross section 15 is determined by the dirction R, but the direction R is set so as to direct in the tangential direction against the axis of a cylinder, and the directions of the respective chamfering parts 17 of exhaust valves 6, 7 are set to be deviated from each other for generating an appropriate swirl flow D. |
