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Among variable valve actuation systems, fully flexible systems such as camless devices are the most attractive valvetrains for near-future engines. This paper presents a research activity about an electro-hydraulic camless system for internal combustion engines. The Hydraulic Valve Control (HVC) system uses hydraulic forces to open the valve while a mechanical spring is used for the closure. The system is fed by an hydraulic pump and two pressure regulators which provide two different pressure levels: a high pressure level (approximately 100 bar) for the pilot stage and a low adjustable pressure level (from 20 to 90 bar) for the actuator power stage. The valve opening duration is controlled by varying the timing of the opening signal of the pilot stage; the valve lift is adjusted varying the oil pressure of the power stage. From a general point of view, the HVC system is an open loop device for engine valve actuation.

This paper presents the further development of an electro-hydraulic camless valve actuation system for internal combustion engines. The system (Hydraulic Valve Control - HVC) is an open loop device for engine valve fully flexible camless actuation. Valve timing and duration are controlled by a pilot stage governed by a solenoid, fast-acting, three-way valve. Valve lift is controlled by varying the oil pressure of the power stage. The system exploits an energy recovery working principle that plays a significant role in reducing the power demand of the whole valve train. In the present paper a new HVC actuator design is presented and its performances in terms of valve lift profile, repeatability and landing are discussed. Experimental data obtained by the application of the HVC system to a motored, single-cylinder research engine have been used to support the numerical evaluation of the potentialities of non-conventional valve actuation in engine part-load operation.

In this paper an experimental analysis is carried out to evaluate the dependence of the flow characteristics in the intake system of a high performance 4 valve, Spark Ignition Internal Combustion Engine, on the experimental conditions at the steady flow test bench. Experimental tests are performed at different pressure levels on a Ducati Corse racing engine head, to measure the Discharge Coefficient Cd and the Tumble Coefficient NT, expanding the work already presented in a previous work by the same research group: with a new test bench, the maximum test pressure level is increased up to 24 kPa, while differently-shaped tumble adaptors are used to evaluate Nt. The study is aimed at determining the influence of the test pressure on Cd and NT measurements, and in particular of the tumble adaptor shape.

This present work is aimed to the analysis of the possible advantages that could be obtained exploiting Variable Valve Actuation strategies in an high performance engine head. A set of experimental tests was carried out to obtain maps of the discharge, tumble and swirl coefficients, at any combination of asymmetric lifts of the two intake valves. The results show that asymmetric strategies could allow engine part load operation characterized by enhanced tumble/swirl generation, while keeping the same effective flow area of conventional two valves symmetric lift. Numerical simulations allowed a deeper understanding of the tumble motion characteristics at different lift combinations, and in particular for asymmetric low lifts cases where the lack of the typical abrupt tumble rising zone was noted.

This paper describes a research activity, carried out at the University of Perugia, focused on the modelling of an automatic reed valve in a coupled fluid-structure approach. The application here concerned is a reed device used to control a Secondary Air Injection (SAI) system which allows ambient air to enter the exhaust pipe upstream of the catalyst (useful for the reduction of emissions in rich mixture engine operating conditions). Since currently no commercial codes are still available for simulating in a comprehensive way the non-linear dynamics of a reed valve device with position constraints, the main objective of the work is the calculation of the air mass flow rate admitted to the exhaust system through the reed, by means of a slim and easy software tool. The task is accomplished by integrating two different codes, developed by the authors.

Modeling and studies on reed valve devices are topics often dealt with when designing internal combustion engine intake and exhaust systems. This paper describes an activity about the modeling and the optimization potentiality of an engine equipped with a secondary air injection system by means of a reed valve device. The first step of the work dealt with the development and tuning of a non-linear Finite Element model of reed valve and with the integration of this model into a one-dimensional fluid-dynamics simulation code. In particular during this phase the potentialities of the method were tested by implementing the FE model both in a 1D University code and in a 1D commercial code (by means of a provided interface for User Defined Elements). In the second step of the work the simulation results were analyzed for different engine operating points.