Variable valve actuating mechanism with magnetorheological fluid lost motion device

摘要

Variable valve mechanisms utilize magnetorheological fluid (MRF) in lost motion devices for controlling lift and timing of engine valves and the like. The lost motion devices are designed with either of two operational modes, a direct shear mode and a valve mode. In the shear mode, the MR fluid is retained between relatively movable shear surfaces of a lost motion device and the relative motion is controlled by varying the shear strength of the fluid by a magnetic field applied to the MR fluid between the shear surfaces. In the valve mode, the flow rate of MR fluid through an orifice is controlled by varying the magnetic field to control the flow viscosity of the fluid passing through the orifice. The lost motion device units may be applied directly between an input cam and an output valve or may be applied to a pivot for a finger follower or another type of valve actuation.