Session: MR-01-01 - Mechanisms Synthesis & Analysis

Paper Number: 87942

87942 - Analysis of the Finger Geometry in Finger Follower Mechanisms for Follower Spin Enhancement 

This article details the kinematics of finger-follower mechanisms in the spatial domain for the assessment of the follower spin motion. The proposed literature survey clarifies that the finger follower valve train is actually a spatial mechanism, despite it is often studied as a planar linkage. The extensive numerical and experimental works available clearly demonstrate that the overall dynamics can be satisfactorily captured by using the 2D approach, since the main motion is effectively a planar motion. However, the design of the mechanism needs to take into account also the secondary motions as they have primary consequences on its reliability. In this context, the present work evaluates the effectiveness of the cylinder-on-sphere coupling between finger and follower in defining a satisfactory valve spin pivoting radius. The study compares it with the cone-on-sphere contact condition, representing the classical layout for spin enhancement borrowed from cam tappet mechanisms. As a matter of fact, the use of conic surfaces for fingers has been borrowed from cam tappet layouts, in which it represents an unavoidable design choice. On the other hand, this solution does not constitute a mandatory selection for fingers and the modern design tools and production capabilities provide the chance to evaluate further configurations. An analytical dissertation based on a geometrical approach is proposed to detail the kinematics of the two layouts, showing that the cylinder-on-sphere coupling provides a higher number of design parameters to fully determine the system, adding flexibility to the design procedure. A parametric study focusing on the declivity of the contact surface is performed, showing the possibility to control the declivity of the cylinder surface along different planes may improve the stability of the mechanism behavior with respect to the production tolerances.

Presenting Author: Mattia Battarra University of Ferrara

Presenting Author Biography: Assistant Professor of Mechanics of Machines and Vibrations at the Engineering Department of the University of Ferrara. In this role, Dr. Battarra is lecturer of Vehicle Dynamics in the Master Degree of Mechanical Engineering at the University of Ferrara and co-tutor of two PhD students.<br/>He got the PhD in Mechanical Engineering from the University of Ferrara in 2018, obtaining the “Department of Engineering UNIFE Best PhD Thesis Award 2018”. His research activity is focused on kinematics, dynamics and design of positive displacement pumps and dynamic models of mechanical systems. He took part to the European project COST Action TU1105 as a visiting research student at the Dynamics Research Group, Loughborough University, UK dealing with the definition of NVH technics for Hybrid and Electric Vehicles. In 2016, he has been Visiting Scholar at the GearLab Research Group, The Ohio State University, OH – US, with the purpose of deepening his studies on the modeling of gear dynamics.

Authors:

Mattia Battarra University of Ferrara
Emiliano Mucchi University of Ferrara