Virtual Check Valve Control for Improved Energy Conservation and Phasing Performance

This paper describes an enhanced application of variable cam timing (VCT) systems for improved conservation of energy and phase rate performance at high temperature and low RPM conditions. This virtual check valve control is demonstrated to provide faster phase rate at high temperature and low RPM conditions than either conventional VCT systems, or those using mechanical check valves. It offers expanded temperature and RPM operating range and further removes VCT systems from imposing burden on fuel-economy-sensitive oil pump systems. The virtual check valve concept is demonstrated in simulation. An ECU control is implemented and tested on a V6 engine.