Electronic Variable Geometry Turbocharger (VGT) Control Valve
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The electronic variable geometry turbocharger (VGT) control valve is a four-way proportional hydraulic flow control valve with closed center position. The valve controls linear actuator position of a closed loop hydraulic servo by charging and venting flow on both sides of a piston. Linear displacement feedback from the actuator varies a feedback spring force to move the valve spool to the center closed position when the actuator reaches the desired position. Therefore, actuator position is dependent only on control valve current - it is independent of hydraulic fluid temperature and viscosity.