System for Varying Cylinder Valve Timing in an Internal Combustion Engine

摘要

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.

主权项

1. A control system for varying cylinder valve timing of an internal combustion engine that has a pump, a reservoir, a crankshaft, and a camshaft; said control system comprising:
a cam phase actuator for adjusting a rotational phase of the camshaft relative to the crankshaft and having a first actuator port and a second actuator port; a first control valve comprising a first port operatively connected to receive fluid from the pump, a second port, and a first workport in fluid communication with the first port of the cam phase actuator, the first control valve having a first position in which a first fluid path is provided between the first port and the first workport, and having a second position in which a second fluid path is provided between the second port and the first workport; a second control valve comprising a third port operatively connected to receive fluid from the pump, a fourth port, and a second workport in fluid communication with the second actuator port, the second control valve having one position in which a third fluid path is provided between the third port and the second workport, and having another position in which a fourth fluid path is provided between the fourth port and the second workport; a first check valve operatively connected to restrict fluid to flow through the first path only in a direction from the pump to the cam phase actuator; and a second check valve operatively connected to restrict fluid to flow through the third path only in a direction from the pump to the cam phase actuator.