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The use of Variable Valve Actuation (VVA) systems offers many advantages in terms of increased engine power, reduced fuel consumption and pollutant emissions, accomplishing a significant improvement of the global efficiency of the engine. In the last decade different devices have been proposed to implement advanced and innovative VVA managements on four-stroke engines. ElectroMechanical Valve Actuator (EMVA) formed by two opposite magnets and two balanced springs seem to be a very promising solution among several camless actuation systems. This type of valve actuator is characterized by highly nonlinear and strongly coupled dynamics which makes very difficult to govern engine valve motion during the last part of the closing and opening strokes, where an unstable behavior is exhibited. In this regard the control problem of the EMVA is tackled in this paper.

In automotive industry the Electronic Throttle Body (ETB) plays a crucial role in drive-by-wire operations since it controls the incoming air into the engine and so the produced torque. This implies the performances of the vehicle in terms of traction, emissions, idle speed regime, cold starting management, thermal transient and smoother movement during tip/in tip/out, strongly depends on the precise control of this device [17]. Despite its apparent simplicity, the behavior of the ETB is affected by many nonlinearities and uncertain parameters which can dramatically alter its dynamics. In order to cope the unwanted nonlinear phenomenons (stick-slip motion, hysteresis, hunting, impact, caos), sophisticated model based control strategies and compensators are proposed in the literature. A time consuming identification parameters of the throttle is fundamental for these approaches and it is the main drawback for their application.

In this work the authors present a model to simulate the in-cylinder pressure oscillations due to knock. Pressure oscillations are predicted by the explicit integration of a Partial Differential Wave Equation (PDWE) similar, in its structure, to the so-called “Equation of Telegraphy”. This equation differs mainly from the classical wave formulation for the presence of a loss term. The general solution of such equation is obtained by the Fourier method of variables separation. The integration space is a cylindrical acoustic cavity whose volume is evaluated at the knock onset. The integration constants are derived from the boundary and initial conditions. A novel approach is proposed to derive the initial condition for the derivative of the oscillating component of pressure. It descends, conceptually, from the integration of the linearized relation between the derivative of pressure versus time and the expansion velocity of burned gas.