Search Results

This paper deals with the design and manufacturing of a mechanical variable valve actuation system, developed as part of the MUR financed research project concerning the realization of a high performance motorcycle engine, through a partnership of Moto Morini S.P.A. (BO), Dell’Orto S.P.A. (MI), Istituto Motori - CNR (NA), and DIME - Università di Napoli Federico II. After a synthetic description of the main variable valve actuation methods currently employed (timing, duration and lift variation, cyclic cylinder deactivation), the paper presents the results of our mechanical variable valve actuation system, consisting of three main elements: cam, main rocker arm with fixed fulcrum and secondary rocker arm with mobile fulcrum. It enables valve lift variation through a simple translation of the intermediate element (system 1).

The dual-fuel (diesel/natural gas, NG) concept represents a solution to reduce emissions from diesel engines by using natural gas as an alternative fuel. As well known, the dual-fuel technology has the potential to offer significant improvements in the emissions of carbon dioxide from light-duty compression ignition engines. A further important requirement of the DF operation in automotive engines is a satisfactory response in a wide range of load levels. In particular, the part-load levels could present more challenging conditions for an efficient combustion development, due to the poor fuel/air ratio. Basing on the above assumptions, the authors discuss in this article the results of a combined numerical and experimental study on the effect of different injection timings on performance and pollutant fractions of a common rail diesel engine supplied with natural gas and diesel oil.