HISTORICAL REVIEW OF VARIABLE VALVE ACTUATION SYSTEMS | ||
| The International Conference on Applied Mechanics and Mechanical Engineering | ||
| Article 90, Volume 13, 13th International Conference on Applied Mechanics and Mechanical Engineering., May 2008, Pages 12-38 PDF (1.73 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/amme.2008.39647 | ||
| Authors | ||
| PATRIZIO NUCCIO; MARIO R. MARZANO | ||
| Professor, Department of Energetics, Politecnico di Torino, Italy. | ||
| Abstract | ||
| ABSTRACT The internal combustion reciprocating engines that are usually employed in automotive applications need high torque at low revolution speeds to quickly increase car velocity without shifting gears. However, high power at top speed is required to obtain an adequate maximum speed as well as sufficient acceleration, through up-shifting. Designers can decide, according to different valve-timing diagrams, whether to improve torque at low speeds or power at top speeds. Unfortunately, both these improvements cannot be carried out at the same time, if the valve-timing diagram does not change with the engine revolution speed. Therefore, the current solutions for ordinary massproduced automotive engines are often a compromise between torque and power performance. A suitable choice of intake-valve and exhaust-valve timing, by means of Variable Valve Actuation (VVA), could instead satisfy both these requirements at the same time and even reduce fuel consumption and pollutant emissions. The aim of this review is to outline some of the most significant proposals over the last forty years as far as VVA systems are concerned. | ||
| Keywords | ||
| Variable Valve Actuation System | ||
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