Electro Hydraulic Gas Exchange Valve Actuation of 4-Stroke Large Bore Diesel Engine

Abstract

After several years of study, a large bore diesel engine Electro-Hydraulic Valve Actuation (EHVA) system has reached a development point where the system has been successfully used for years in laboratory test engine environment too. During the evolution of the EHVA, insight of the hydraulic and control systems features has been cleared. This paper concludes main findings and results of EHVA research in Tampere University of Technology / IHA. The hydraulic circuit effect to the power consumption of EHVA is clear. 3-way controlled actuator has advantages compared to 4-way controlled system. Direction control valve defines controllability of the system, and has source of the largest single component power loss. Hydraulic actuator design has also a fair effect to the overall power consumption when pressure force vs. required flow changes heavily, due to load forces. Mechanically, return spring design of the gas exchange valve has great effect to power consumption too. Controller design is dependent on what kind of performance is required. The controller compensates lack of control valve bandwidth, and reacts to changing environmental variables. In this state, the Iterative Learning Controller (ILC) has proved the best choice. If gas exchange valve exact lift motion during the lift event is not important but variation between the strokes is kept in narrow range, a Model-Based Controller (MBC) is a strong option.