Single-Cylinder Engine Tests of a Motor-Driven, Variable-Valve Actuator

A novel mechanism concept for a fully flexible, motordriven, cam-actuated engine valve was reported in [1]. It is capable of i) variable valve timing, ii) variable lift and iii) individual valve phasing control. To check the validity of the concept in real engine environment, engine tests were performed using a single-cylinder of a modified sixcylinder 3.8-liter production engine, with the new motordriven mechanisms replacing both valves. Firing tests of this engine, with equivalent valve profiles to the production profiles, yielded similar fuel consumption, lower NOx emissions but higher IMEP COV and HC emissions. Motoring tests demonstrated variable timing capability, low cycle-to-cycle valve lift-profile variation as well as low seating velocity and noise. Lessons learned from testing the system in a real engine environment are discussed in details and suggestions for future variablevalve actuation concepts' requirements are offered.