A New Hydraulic Servo Variable Valve Actuation Concept - Simulation Studies 2007-01-1298

Valve actuation parameters like lift, opening and closing times affect performance and emissions of an engine. In this work, a new hydraulic variable valve actuation (VVA) concept is explained, simulated and analyzed using MATLAB. The system applies differential hydraulic pressure on two sides of a piston to open the inlet valve. A system of orifices, one of fixed diameter and the other of variable diameter is used to control the differential pressure. Some of the key parameters, which affect the performance of the system, are fluid supply pressure, damping, orifice diameters, displacement of the plunger controlling the orifice and the spring stiffnesses. The variation of parameters like the plunger movement, inlet and exit areas in a certain way was found to reduce the response time as well as increase the lift. It was also observed that the valve lift could be varied from 3.5 mm to 8 mm by just a 1.5 mm movement of the solenoid actuator. This makes the system extremely suitable for present day high speed engines. Also the valve seating velocities obtained were low, thus proving to be a good design.