Parker Abex – Jet Pipe Servos Electrohydraulic Servovalves Nuclear, Steam and Gas Power Plant Applications Unique Jet Pipe® First Stage Design
Presentation Abstract Pedigree – Parker Non-Incendive Jetpipe Electro-Hydraulic Servovalve Design Hydraulic Design Features & “Varnishing” Special note on A160 varnishing Performance of Jetpipe Design Versus Flapper Style Servovalves “Intrinsically Safe” vs “Non-Incendive” Designs Open Questions
Presentation Abstract (cont.) Goal is 20 minutes ppt, 25 minutes questions/open discussion Single task is to show how Jetpipe Servo design is more robust/fail resistant in harsh oil environments (i.e. A160 lube skid) Presenter is Sr. Engineer at Electro Hydraulic Servovalve Division Asst. will be handy to help with more specific 7FA related questions Following Slides Give a Flavor of ppt
Servo Controls Division Uniquely positioned for the powergen market Over 40 years as a supplier to the Power Gen Market EHSV’s specified on over 40 GE drawings Unique Jet-Pipe® construction 5-70 GPM 1, 2 or 3 coil models available Factory Mutual Approved Intrinsically Safe Models by 2Q ‘04 Complete R & O facilities-to OE requirements Single sourcing within Parker enables access to over 500,000 parts
SERVO CONTROLS DIVISION JET-PIPE OPERATION Figure 1 — Servovalve at null High pressure filtered fluid flows to the flexible feed pipe attached at the base of the torque motor, to the top of the jet pipe, and out the projector jet. Fluid from the projector jet impinges upon the receiver. Two small orifices are connected hydraulically to the ends of the second-stage spool. With the servovalve at null, the projector jet is centered over the receiver holes and equal pressures are developed at each end of the spool.
SERVO CONTROLS DIVISION JET-PIPE OPERATION Figure 2 — Actuation Input current is applied to the torque motor. A magnetic torque is produced causing the armature and the attached jet pipe with projector jet to rotate through a very small angle. The polarity will cause the jet pipe to move left or right.. The projector jet movement causes differential pressure across the second-stage spool causing movement. As t he spool moves, the feedback spring pulls the jet pipe back against the magnetic torque toward the center of the receiver. When the feedback spring force is equal to the magnetic force, the projector jet will again be centered over the receiver generating equal pressure at each end of the spool, and spool movement stops at the new position. Fluid will now flow from the second stage pressure port to the cylinder port C2, through the actuator, and back through cylinder port C1 to return. A reversal of the input current results in an opposite motion of the spool, changing the direction of the flow to the actuator.
SERVO CONTROLS DIVISION JET-PIPE SERVO VALVES Excellent contamination resistance. Jet-Pipe allows larger particulate passage than nozzles. Additionally, high spool-driving forces and long power-stage strokes help our Jet-Pipe servovalves deliver premium contamination resistance – the highest in the industry. The reliability leader. Rugged servovalve design and construction combine with excellent contamination resistance to make Parker’s Jet-Pipe servovalve the industry leader in performance and reliability. Low life-cycle costs. High reliability minimizes servovalve and actuator maintenance, significantly reducing life-cycle costs