A Novel, Fully Flexible, Electro-Mechanical Engine Valve Actuation System 970249
A novel, fully flexible engine valve actuation mechanism was built and tested for the first time. It consists of a permanent magnet brushless dc motor driving a cam mechanism to actuate each engine poppet valve. This mechanism has the advantages of low friction, low seating velocity and speed range comparable to that of production valve trains. The electromechanical system has also regeneration capabilities which result in an energy requirement that is equivalent to or lower than the valve-train friction of current production engines. The valve event duration is changed by increasing or decreasing the cam/motor angular velocity during valve opening in order to shorten or lengthen the valve event, respectively. Part-lift operation is also possible by oscillating the mechanism around the valve opening or closing points. The prototype mechanism was run on the bench on an actual engine cylinder head at speeds of up to 3225 r/min, equivalent to 6450 engine r/min. It demonstrated good flexibility in variable timing and part-lift operation. In addition, valve deactivation should be possible at all engine speeds.