Abstract

The cam phaser of the present invention includes an externally mounted DPCS (234) with spool position feedback to control the position of a center mounted spool valve (192) and control the phase angle of the cam mounted phaser. A position sensor (300) is mounted to the spool valve position such that a control loop (400) controls the position of the spool valve (192). A second, outer loop (430) controls the phaser angle. An offset is preferably added to the spool valve position to move the spool valve to its steady state or null position. This null position is required so that the spool (200) can move in to move the phaser in one direction and outward to move the phaser in the other direction. This type of system reduces any frictional or magnetic hysteresis in the system.