| 摘要 |
PURPOSE: A method for reducing the noise of a cam phaser by controlling the position of a center-mounted spool valve is provided to reduce the noise caused by torsional reversals of a rotor hitting a phaser housing in a VCT(Variable Camshaft Timing) cam timing system. CONSTITUTION: In a cam torque actuated phaser disposed between a first moving shaft and a second moving shaft, the phaser has a first end connected to the first moving shaft and a second end connected to the second moving shaft. A housing is connected to the first end and a rotor is connected to the second end. The rotor forms at least one vane(642) disposed within the housing and divides the housing into an advance chamber(692) and a retard chamber(693). The vane is limited by at least one physical stop caused by an inside surface of the housing. The phaser is coupled to at least one check valve(615,697) and controlled by a feed back control loop having a control law. An integrator accumulates a plurality of error signals resulting from the difference between a set point control signal and a feedback signal. In addition, the phaser has a spool valve(614) having a predetermined null position. A method for reducing the noise of a cam phaser is composed of steps for moving the spool valve just off the predetermined null position; permitting control fluid to flow at a substantially slow rate; and positioning the vane at a substantial distance away from the physical stops and accordingly reducing noise caused by the vane contacted with the housing.
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