Introduction to Electro-hydraulic Proportional and Servo ...

1 Introduction to Electro-hydraulic Proportional and Servo Valves 1. Servo Proportional Valves Valves Mobile bankable NFPA Mounting NFPA Mounting Servo Servo Valves Style, Threaded Without Spool With Spool Performance, With either Cartrdige Style Position Position Closed Loop Mechanical or Feedback Feedback Valves with Spool Electrical Position Feedback Feedback (spool position). Parker Models Pulsar VP, D*FWs, D*FTs' D*FXs' D*FP BDs'. VPLs. D*FHs DYs'. D*1FH SEs'. Mechanical Electro-hydraulic Electromagnetic Electromagnetic Electromagnetic Torque Motor Pilot Construction Pilot, Force, Force, Force, Mechanical Control (spool shift) Mechanical Mechanical Mechanical (spring) Return Balance PSI spool (spring) Return (spring) Return (spring) Return Control Hysteresis 3 ..7% 3 7% ..1% .5% .. Frequency < 10 Hz 10 50 Hz 10 .70 Hz Hz 100 200 Hz Response Center Lap Overlap 5 20% Zero Overlap Zero Overlap Condition Operating 1000 2000 PSI 1000 3000 PSI None Pressures Limits (Drop across metering edge).

2 Applications Open Loop Control Low End Closed Closed Loop Closed Loop Loop Position Position & Force Position & Force 2. Meter Out Circuit P to A. B to T. T P T. Free flow into the cap end Metered Flow out the head . end. A B. 3. Meter Out Circuit P to B. A to T. T P T. Free flow into the cap end Metered Flow out the head . end. A B. 4. Electrohydraulic Valves P to A. B to T. T P T. Shift Spool slightly to create A B. metering Orifice 5. Servo Proportional Valves Valves Mobile bankable NFPA Mounting NFPA Mounting Servo Servo Valves Style, Threaded Without Spool With Spool Performance, With either Cartridge Style Position Position Closed Loop Mechanical or Feedback Feedback Valves with Spool Electrical Position Feedback Feedback (spool position). Parker Models Pulsar VP, D*FWs, D*FTs' D*FXs' D*FP BDs'. VPLs. D*FHs DYs'. D*1FH SEs'. Mechanical Electro-hydraulic Electromagnetic Electromagnetic Electromagnetic Torque Motor Pilot Construction Pilot, Force, Force, Force, Mechanical Control (spool shift) Mechanical Mechanical Mechanical (spring) Return Balance PSI spool (spring) Return (spring) Return (spring) Return Control Hysteresis 3.

3 7% 3 7% ..1% .5% .. Frequency < 10 Hz 10 50 Hz 10 .70 Hz Hz 100 200 Hz Response Center Lap Overlap 5 20% Zero Overlap Zero Overlap Condition Operating 1000 2000 PSI 1000 3000 PSI None Pressures Limits (Drop across metering edge). Applications Open Loop Control Low End Closed Closed Loop Closed Loop Loop Position Position & Force Position & Force 6. Sectional Valves VPL Series C2 C1. Limiter Compensator P. T. 7. Sectional Valves VPL Series Pulsar Cyl. Relief Solenoid Anti-Cav. Check C1. Pressure Manual Limiter Override Flow Limiters Individual C2. Optional Compensator Pressure Port Limiter 8. Sectional Valves VPL Series (C1 Energized). 9. VPL Main Spool 8 Flow Rates ( , , 4, 7, 11, 17, 24, 30 GPM). OCM. VOC. CC Spool Meter-In Lands Marking Ex. 524. Centering Spring 200 or 350 PSI Meter-Out Lands Regenative Detent & Friction-Lock also Available Options 10. Compensation, VPL.

4 Series Pressure compensation maintains a constant flow regardless of pump pressure, load pressure, or any other load in the system This means when running multiple sections at the same time, there will be no change in speed Standard Spool / Springs for complete flow range 11. VPL Compensator Components 3 Sizes of Shims (.003 .008 .025 ). 12. Servo Proportional Valves Valves Mobile bankable NFPA Mounting NFPA Mounting Servo Servo Valves Style, Threaded Without Spool With Spool Performance, With either Cartridge Style Position Position Closed Loop Mechanical or Feedback Feedback Valves with Spool Electrical Position Feedback Feedback (spool position). Parker Models Pulsar VP, D*FWs, D*FTs' D*FXs' D*FP BDs'. VPLs. D*FHs DYs'. D*1FH SEs'. Mechanical Electro-hydraulic Electromagnetic Electromagnetic Electromagnetic Torque Motor Pilot Construction Pilot, Force, Force, Force, Mechanical Control (spool shift) Mechanical Mechanical Mechanical (spring) Return Balance PSI spool (spring) Return (spring) Return (spring) Return Control Hysteresis 3.

5 7% 3 7% ..1% .5% .. Frequency < 10 Hz 10 50 Hz 10 .70 Hz Hz 100 200 Hz Response Center Lap Overlap 5 20% Zero Overlap Zero Overlap Condition Operating 1000 2000 PSI 1000 3000 PSI None Pressures Limits (Drop across metering edge). Applications Open Loop Control Low End Closed Closed Loop Closed Loop Loop Position Position & Force Position & Force 13. How does it Work? (No Spool Feedback). Integrated Electronics . (PWD Amplifier). Solenoid B . Solenoid A . Command Signal based upon a % of Maximum. Typically 0 to +/- 10 VDC. Amplifier converts Voltage (Command) into Proportional Current (Typically Amps). Variable DC current into solenoid assembly produces Electromagnetic Force, Proportional to current applied. By matching Opposition Spring Force to Solenoid Force, Proportional Spool Movement is obtained. 14. How does it Work? Proportional Solenoid Construction Frame Winding Plunger (armature).

6 Push pin 15. How does it Work? Solenoid Operation .5 VDC 50%.. 16. Proportional Valve Spool Designs V-Notch Spool C-Notch Spool 17. Proportional Valve Spool Designs P-A-B-T = 145 PSI. 100. 90. 80. FLOW AREA %. 70. 60. 50. 40. 30. 20. 10. 0. 0 20 40 60 8 100. SPOOL SHIFT, %. P-A-B-T = 145 PSI. 100. 90. FLOW AREA % 80. 70. 60. 50. 40. 30. 20. 10. 0. 0 20 40 60 8 100. SPOOL SHIFT, %. 18. V-Notch - Bleed Center bleed notch primary metering notch 19. Proportional Valve Deadband T Ps T. A B. 20. Positive Overlap + Spring Force + Q. - + I. Mechanical Spool Overlap (Deadband). 21. Deadband Eliminator 100 K . 100 K . - 100 K . Vin +. 100 K . - + DBE. + Vout - 100 K +. +s s DBE. + VCC VCC 100 K . 22. Deadband Compensation + Q. - + I. Deadband Compensation 23. Deadband Compensation + Q. - + I. Deadband Over Compensated 24. Valve Drivers (Open Loop) On Board Integrated Electronics 25.

7 Valve Drivers (Open Loop) On Board Integrated Electronics (Pot adjustments). Ramp Pots Max Pots MIN Pots 26. Valve Drivers (Open Loop) On Board Integrated Electronics (PC Adjustments). Digital Onboard Electronics D1FB*0 OBE. 27. Deadband Eliminator P to A flow Path T Ps T. A B. 28. Deadband Eliminator (P to B flow Path). T Ps T. A B. 29. Servo Proportional Valves Valves Mobile bankable NFPA Mounting NFPA Mounting Servo Servo Valves Style, Threaded Without Spool With Spool Performance, With either Cartrdige Style Position Position Closed Loop Mechanical or Feedback Feedback Valves with Spool Electrical Position Feedback Feedback (spool position). Parker Models Pulsar VP, D*FWs, D*FTs' D*FXs' D*FH BDs'. VPLs. D*FMs DYs'. DF**, ERVs D*1FH SEs'. Mechanical Electro-hydraulic Electromagnetic Electromagnetic Electromagnetic Torque Motor Pilot Construction Pilot, Force, Force, Force, Mechanical Control (spool shift) Mechanical Mechanical Mechanical (spring) Return Balance PSI spool (spring) Return (spring) Return (spring) Return Control Hysteresis 3.

8 7% 3 7% ..1% .5% .. Frequency < 10 Hz 10 50 Hz 10 .70 Hz Hz 100 200 Hz Response Center Lap Overlap 5 20% Zero Overlap Zero Overlap Condition Operating 1000 2000 PSI 1000 3000 PSI None Pressures Limits (Drop across metering edge). Applications Open Loop Control Low End Closed Closed Loop Closed Loop Loop Position Position & Force Position & Force 30. Spool Feedback, How does it Work? Spool Position LVDT Integrated Electronics . (PWD Amplifier). Solenoid B . Solenoid A . Same basic operation as non-feedback valves, but outcome is measured and corrected to match desired result. Closing the Loop . 31. Spool Feedback Device Linear Variable Differential Transformer Input V DC. Oscillator Primary Spool Core Secondary Secondary Output V DC. Demodulator 32. 33. Spool Feedback Devices (Electrical Schematic-Integrated Electronics). Disturbances adj CMD + Error I F. A.

9 FB - X. LVDT. 34. Internal Closed Loop Force u s Command Signal Valve position feedback 35. Sample Application 36. Kv Sizing 37. Non-Symmetrical Spools 38. Sample Application, Number 2. 39. Non-Symmetrical Spools (P-A-B-T = 145 PSI). 10. 5. Flow Rate, GPM. 0. -10 -5 0 5 10. -5. -10. Valve Command, Volts 40. Common Procedure The manufacturer can choose to take a standard 10gpm valve with normally 4 notches on each land and only cut two notches in the land that will be connected to the small area of the cylinder. 3 notches instead of 4. 4 notches instead of 6. 2 notches instead of 6 . 41. Non-symmetrical Spools T P T. A B. holes .85holes A B. PS. holes .85holes 42. Sample Application No. 2 with Non- Symmetrical Spool 43. Flow Force Effects Proportional Valves Flow X. 44. Flow Force Performance Operating Limits Curves show Valve Performance over entire Pressure Range 45.

10 Servo Proportional Valves Valves Mobile bankable NFPA Mounting NFPA Mounting Servo Servo Valves Style, Threaded Without Spool With Spool Performance, With either Cartrdige Style Position Position Closed Loop Mechanical or Feedback Feedback Valves with Spool Electrical Position Feedback Feedback (spool position). Parker Models Pulsar VP, D*FWs, D*FTs' D*FXs' D*FH BDs'. VPLs. D*FMs DYs'. DF**, ERVs D*1FH SEs'. Mechanical Electro-hydraulic Electromagnetic Electromagnetic Electromagnetic Torque Motor Pilot Construction Pilot, Force, Force, Force, Mechanical Control (spool shift) Mechanical Mechanical Mechanical (spring) Return Balance PSI spool (spring) Return (spring) Return (spring) Return Control Hysteresis 3 ..7% 3 7% ..1% .5% .. Frequency < 10 Hz 10 50 Hz 10 .70 Hz Hz 100 200 Hz Response Center Lap Overlap 5 20% Zero Overlap Zero Overlap Condition Operating 1000 2000 PSI 1000 3000 PSI None Pressures Limits (Drop across metering edge).