Patent ID: 7469669
Filing Date: 2008-12-30
Classification: F01L

Abstract:
1. A variable valve train mechanism of an internal combustion engine, configured to change a lift of an intake valve or an exhaust valve of the internal combustion engine, the variable valve train mechanism comprising: a camshaft rotationally driven by a crankshaft of the internal combustion engine, a rotational cam disposed on the camshaft; a swing shaft disposed parallel to the camshaft, and a swing cam supported with the swing shaft and being swingable with a movement of the rotational cam, wherein the swing cam has a movable rotational cam abutment portion which contacts the rotational cam and transmits driving force from the rotational cam to the swing cam, and a guide portion for guiding the rotational cam abutment portion in a certain direction, the swing cam being configured to input the driving force from the rotational cam is to the guide portion via the rotational cam abutment portion so that the swing cam is swung with a movement of the rotational cam, the swing cam also comprising a contoured cam face; an abutment portion displacing mechanism configured to displace the rotational cam abutment portion along the guide portion so as to change a relative distance between the rotational cam abutment portion and a center axis of the swing shaft, the abutment portion displacing mechanism comprising a drive shaft formed continuously from the swing shaft along its axial direction and having a center axis parallel to and eccentric from the center axis of the swing shaft, and an arm with one end connected to the rotational cam abutment portion and the other end connected to the drive shaft; and a rocker arm that is configured to be swung by the swing cam and a spring configured to urge the rocker arm toward the swing cam, the rocker arm having a follower configured to contact the contoured cam face of the swing cam; wherein as the swing shaft is rotated to displace the drive shaft around the center axis of the swing shaft, the rotational cam abutment portion is displaced through the arm, so that the relative distance between the rotational cam abutment portion and the center axis of the swing shaft is changed and a relative position of the follower and the contoured face is changed, whereby a lift of the valve is changed; wherein the guide portion is configured to allow the swing cam to swing through a range of orientations corresponding to a large lift zone, a small lift zone, and an idle running zone which overlaps with both of the large and small.