Title: Hydrodynamic model of valve train systems support

Authors: Alexandre Mastaler, Katia Lucchesi Cavalca

Addresses: Schaefler Brasil Ltda, INA Division, Av. Independencia 3500, 18087-101 Sorocaba SP, Brazil. ' Department of Mechanical Design, Unicamp Postal Box 6051, 13083-970 Campinas SP, Brazil

Abstract: The main objective of this research is to find the range of normal forces for a complete turn of the cam, depending on the axial tilting angle of the tappet to drive the tappet spin, minimising its wear effect. The valve train system used in combustion engines has the function of controlling the opening and closure of gas circulation valves, that takes part in combustion process. One of its systems is the rocker arm/hydraulic lash adjuster contact. The knowledge of this sub-system is important to wear and noise evaluation that come from this contact as well as friction evaluation for the command general optimisation. To reduce wear, the tappet must spin with respect to the rocker arm. The oil film around the tappet is represented by its pressure distribution, evaluated from the Reynolds Equation. Considering the friction and the moments generated by the axial tilting in the tappet, an equilibrium condition is reached, defining the tappet spin with respect to the rocker arm.

Keywords: valve train systems; hydrodynamic pressure distribution; axial tilting; tappet spin; wear evaluation; combustion; gas circulation valves; noise evaluation; friction evaluation; rocker arm; oil film pressure; vehicle design.

DOI: 10.1504/IJVD.2007.013224

International Journal of Vehicle Design, 2007 Vol.44 No.1/2, pp.167 - 187

Published online: 12 Apr 2007 *

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