Patent ID: 7610881
Filing Date: 2009-11-03
Classification: F01L,F02D,F02M,Y02T

Abstract:
1. A valve actuation system for providing added motion in a valve mechanism of an internal combustion engine, the valve actuation system comprising the valve mechanism, the valve mechanism comprising at least one inlet valve and at least one exhaust valve, the valve mechanism comprising a rotatable camshaft with a cam curve including rising and falling ramps designed to interact with a valve control plunger that is movable inside a cylinder for actuation of the inlet or exhaust valve under action of a valve spring, the plunger cylinder communicating with a hydraulic fluid feed line via a check valve and with a hydraulic control circuit allowing a return movement of an engine valve to be delayed in relation to the timing of the corresponding falling ramp, wherein the hydraulic control circuit comprises a first and a second hydraulic fluid flow restrictor connected to the plunger cylinder at different levels along a longitudinal axis of the plunger cylinder, and a selector valve enables a connection between the cylinder and hydraulic control circuit to be opened via at least one of the first and second flow restrictors.