US Patent 7500466 Variable valve actuation and engine braking

Systems and methods of actuating two engine valves associated with a common engine cylinder using one or more lost motion systems and one or more control valves are disclosed. The control valves are capable of selectively trapping hydraulic fluid in the lost motion systems for auxiliary engine valve actuations and selectively releasing the hydraulic fluid to default to cam controlled valve seating of the engine valves. The systems may provide a combination of main exhaust, compression release, exhaust gas recirculation and early exhaust valve opening in preferred embodiments.