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

2025-32-0010

To be published on 11/03/2025

Event
SETC2025: 29th Small Powertrains and Energy Systems Technology Conference
Authors Abstract
Content
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 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 works aims at developing a numerical model of the 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 and to estimate the overall system efficiency. The model is structured into two subsystems: the timing chain model and the valve model. The chain model includes the sprockets (drive, intake, and exhaust), chain tensioner arm, chain guide and silent chain, while the valve model includes the camshafts (intake and exhaust), bearings, finger follower and valve assembly (which includes valve, spring, retainer, and valve seat). Results show how the elastic and damping characteristics of each component affect the dynamic behaviour of the system and the influence of contact parameters between parts. For each time step, the contact pressure distribution is shown and used to evaluate the most critical stress region. Friction models have been added in the lubricated contacts to evaluate the system's efficiency.
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Citation
Tarchiani, M., pizzicori, A., Raspanti, S., Romani, L. et al., "Advanced 3D Simulations of a Four-Stroke High-Performance Engine Valvetrain for the Analysis of the Mechanical Stresses and Energy Losses," SAE Technical Paper 2025-32-0010, 2025, .
Additional Details
Publisher
Published
To be published on Nov 3, 2025
Product Code
2025-32-0010
Content Type
Technical Paper
Language
English