Advanced 3D Simulations of a Four-Stroke High-Performance Engine Valvetrain for the Analysis of the Mechanical Stresses and Energy Losses Università degli Studi di Firenze

Format:

Book

Conference/Event

Author/Creator:

Tarchiani, Marco, author.

Contributor:

Ferrara, Giovanni

Meli, Enrico

Pizzicori, Alessio

Raspanti, Sandro

Romani, Luca

Trassi, Paolo

Conference Name:

SETC2025: 29th Small Powertrains and Energy Systems Technology Conference (2025-11-10 : Florence, Italy)

Language:

English

Physical Description:

1 online resource cm

Place of Publication:

Warrendale, PA SAE International 2025

Summary:

Enhancing the performance of naturally aspirated 4-stroke engines relies heavily on improving trapping efficiency, increasing maximum engine speed, and reducing friction losses. In this regard, the valvetrain plays a critical role. Achieving high volumetric efficiency at higher engine speeds necessitates very steep valve opening and closing ramps, making this aspect pivotal in the design process. At high engine speeds, significant dynamic phenomena arise, including valve float during the lift phase and valve bounce during the closing phase. These effects not only induce substantial modifications to the valve lift curve but also increase the mechanical stress on critical components such as the valve and the rocker arm, thereby elevating the risk of failure. Moreover, the timing system substantially contributes to overall engine losses due to frictional energy dissipation, which results from the numerous interactions between moving components. The present work aims to develop a numerical model of the intake valvetrain of a high performance 4 stroke, single-cylinder engine, using the advanced 3D solver Comsol Multiphysics to accurately evaluate the stresses and deformations affecting each part. The simulation model includes camshaft, bearing, finger followers and the valves assembly (which includes valve, spring, retainer, and valve seat). Once the model was validated through comparison with experimental valve lift measurement, the interaction forces between the various components and the resulting mechanical stresses were analyzed. Subsequently, an investigation was conducted into the mechanisms responsible for the emergence of dynamic effects. Two different solutions were then tested in order to mitigate them. The use of the simulation software enabled a straightforward modification to be made to the material of the finger-follower, which was replaced with a lighter alternative in order to reduce the reciprocating masses. As a second solution, an alternative cam profile was designed, maintaining the same lift trend. This second approach resulted in a significant reduction of the dynamic effects acting on the valve during the closing phase, completely eliminating valve bounce. Furthermore, it enabled a substantial decrease in the mechanical stresses experienced by components such as the finger-follower and the valve-seat

Notes:

Vendor supplied data

Publisher Number:

2025-32-0010

Access Restriction:

Restricted for use by site license