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SERVO VALVES

SERVO VALVES. SERVO VALVE. A SERVO VALVE IS A DIRECTIONAL VALVE IT MAY BE INFINITELY POSITIONED TO PROVIDE CONTROL OF BOTH THE AMOUNT AND THE DIRECTION OF FLUID FLOW.

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SERVO VALVES

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  1. SERVO VALVES

  2. SERVO VALVE A SERVO VALVE IS A DIRECTIONAL VALVE IT MAY BE INFINITELY POSITIONED TO PROVIDE CONTROL OF BOTH THE AMOUNT AND THE DIRECTION OF FLUID FLOW. A SERVO VALVE COUPLED WITH PROPER FEEDBACK SENSING DEVICES PROVIDES VERY ACCURATE CONTROL OF THE POSITION, VELOCITY OR ACCELERATION OF AN ACTUATOR .

  3. CONVENTIONAL DIRECTIONAL VALVE T B A P

  4. SERVO VALVE - Compare with a Proportional Valve Based on Control Method

  5. SERVO VALVE - Compare with a Proportional Valve Based on Application

  6. PROPORTIONAL VALVES & SERVO VALVES OPEN LOOP & CLOSED LOOP Open Loop circuit : Accuracy, Response : POOR Controllability : GOOD Cost : LESS Controller controls the hydraulic valve according to the input signal which is given from the controller to the valve. SLOW FAST

  7. PROPORTIONAL VALVES & SERVO VALVES Closed Loop Circuit : According to the requirement of speed or position or pressure , input signal is given and compared with output value through a sensor and necessary adjustments are made. Input signal and output values are compared and differences are corrected. This gives high accuracy & high Response ( Feed back Control System ) CONSTANT SPEED

  8. SERVO VALVE Control method in a Proportional Valve

  9. SERVO VALVE Control method in a Proportional Valve By Providing Spool between Magnetic Solenoid and Spring it is possible to control Hydraulic energy.

  10. ELECTRO-HYDRAULIC TWO STAGE SERVO VALVE ARMATURE NULL ADJUST MAGNET UPPER POLEPLATE LOWER POLEPLATE FLAPPER NOZZLE COIL FEEDBACK SPRING BUSHING SPOOL INLET ORIFICE INLET FILTER P A R B

  11. ELECTRO-HYDRAULIC TWO STAGE SERVO VALVE MAGNET Graphic Symbol A B R P Side Sectional View P R

  12. SERVO VALVE - OPERATION • No Signal to Valve Service Service R P

  13. SERVO VALVE - OPERATION • Signal applied to torque motor & spool about to move. Service Service R P

  14. SERVO VALVE - OPERATION • Equilibrium condition with signal applied. Service R P Service

  15. ELECTRO-HYDRAULIC THREE STAGE SERVO VALVE PILOT VALVE SLEEVE L.V.D.T SPOOL Drain Port A B R P

  16. SERVO PILOT PROPORTIONAL VALVE Input Voltage PILOT VALVE SERVO AMPLIFIER SPOOL SPRING L.V.D.T Pilot Pr. Port R A B P

  17. MECHANICAL SERVO VALVE STYLUS SLEEVE SPOOL Drain Port Pilot Pr. Port T A B P

  18. SERVO VALVE - Compare with a Proportional Valve Based on Function

  19. SERVO VALVE - Compare with a Proportional Valve Based on Function

  20. FREQUENCY RESPONSE 38 L/min +2 63 L/min 0 -2 -110  -4 Amplitude Ratio ( Gain ) ( dB ) -6 -90  Phase Lag ( Degrees ) -8 -70  -50  -30  -10  5 10 20 30 50 100 200 Frequency ( Hz )

  21. SERVO VALVE - Compare with a Proportional Valve Performance comparison

  22. SERVO VALVE - Most Sensitive to Contamination

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