Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Patent
1990-05-08
1991-01-22
Myhre, Charles J.
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
123 9039, 123 9041, 123 9044, F01L 118
Patent
active
049862278
ABSTRACT:
A variable lift valve train mechanism for an internal combustion engine. The valve train varies valve lift depending on engine RPM, providing a relatively lower valve lift at lower engine RPMs for increased bottom-end torque and a relatively higher valve lift at higher engine RPMs for increased overall top-end performance. The valve train includes a rocker arm at one end engaging a valve and at its other end engaging a cam such that upward movement of the cam causes downward opening movement of the valve. The rocker arm has a convex fulcrum-engaging upper surface extending between the rocker arm ends. A variable-position fulcrum assembly includes a pivot arm, the lower end of which is pivotally mounted to a pivot point, and the upper end of which carries a fulcrum roller element engaging the fulcrum-engaging upper surface of the rocker arm to define a variable fulcrum point. A control element in the form of a control piston driven by engine oil pressure positions the pivot arm and thus the fulcrum point to vary valve lift. To selectively restrict engine performance, a pressure relief valve may be provided for limiting the oil pressure to the control piston.
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Lo Weilun
Myhre Charles J.
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