A Low-Friction Variable-Valve Actuation Device Part II: Analysis and Simulation 970339

A relatively simple, low-friction Variable-Valve-Actuation (VVA) device is presented. The device can be characterized as a four-bar mechanism consisting of a crank, a rocker and a coupler, all supported on a carrier body. Description of the prototype hardware, and the results of the friction measurements are presented in an accompanying paper [1].
In the present paper, a kinematic analysis/synthesis and a rigid-body dynamic analysis are outlined. Also included is a flexible-body model where the coupler link, which was suspected to be the most severely stressed member, is modeled as a flexible component. A sensitivity-uncertainty analysis employing the Fourier-Amplitude-Sensitivity-Test (FAST) method is conducted to identify the dominant design parameters, and to predict the variations in mechanism's performance due to the uncertainties in the design parameters.
Dynamometer tests reported in [1] confirmed the predictions that, due primarily to the rocking motion at the lifter interface, the mechanism consumes much less frictional-energy than a direct-acting non-roller type valvetrain. It is demonstrated that the mechanism can provide late valve opening, early valve closing, and lower lift.


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