Abstract

To reduce the noise caused by torsional reversals of a rotor hitting the phaser housing in a VCT cam timing system. A cam torque actuated phaser (phaser with check valves) the control loop is opened and rather then moving the spool valve to one end or the other end, the spool valve is moved just slightly off null. By doing this the oil ports in the spool passageways that control the motion of the phaser are restricted and the motion of the phaser is reduced. Therefore the noise of the phaser is reduced.