20140251247 | System for Varying Cylinder Valve Timing in an Internal Combustion Engine - A variable engine valve timing control system has a cam phase actuator, with first and second actuator ports, to adjust a rotational phase of a camshaft relative to a crankshaft. A first control valve selectively couples the first actuator port to either an engine oil pump or a first valve port. A second control valve selectively couples the second actuator port to either the engine oil pump or a second valve port. Separate check valves prevent oil flow backwards through the first and second control valves from the cam phase actuator to the engine oil pump. In one implementation, the first valve port and second valve port are connected to a fluid reservoir. In another implementation, the first valve port is connected by another check valve to the second actuator port, and the second valve port is connected by a further check valve to the first actuator port. | 09-11-2014 |