mfb training

Introduction into the Mechanical FeedBack (MFB) Servovalves

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Assembly of MFB

Valve body

Pilotstage - Torque Motor

Feedback wire

Principle assembly of the a Mechanical FeedBack Valve

Bushing

Spool

Mounting manifold

Connector

Orifice

Filterplate (In P for Pilotstage)

1 2 3

4

5

6

9 8

6

7

2

3

4

5

6

7

8

9

1


Assembly / Torque Motor

Hydraulic Amplifier

Electro MechanicalAmplifier

Nozzle Flapper

This valve type is also called:Nozzle Flapper Stage

Feedback Wire


Ø Charged permanent magnetspolarize the pole pieces

Ø DC current in coils causesincreased force in diagonallyopposite air gaps

Ø Magnetic charge level setsmagnitude of decenteringforce gradient on armature

SS

N N

SSNNcoil flux

Function of Electro-Mechanical AmplifierAssembly / Torque Motor


Ø Armature and flapper rigidly joined andsupported by thin-wall flexure sleeve.

Ø Fluid continuously flows from pressurePs, through both inlet orifices, via thenozzles into the flapper chamber andfinally through the drain orifice to tank T.

FROM SPOOL END TO SPOOL ENDRETURN ORIFICE

Ø Rotary motion of armature /flapper throttles flow through onenozzle or the other

Ø This diverts flow to one end of thespool

Function of the Hydraulic AmplifierAssembly / Torque Motor


Null Position:Null current is supplied to the coils of the Torque Motor and the motor stand in hismiddle position. The gabs between the right-and-left nozzle are the same. Due tothe same gabs the pressure on both spool ends is symmetric. The Spool of themain stage is also located in middle position. Port A and B are closed

Function MFB Valve


Operating:If an input signal is applied the Torque Motor will pull out, therefore the gab betweenthe right-and-left nozzle will change and a different pressure will arise at both sites ofthe spool. Due to the Delta P on the spool ends the spool will move. Thus thefeedback wire will bent according to the displacement of a spool. The Ports P to Aand the Port B to T will open and oil will flow through the BSA of the main stage.

Movementof spool

bent feedback wire

Function MFB Valve


Position reached:As feedback torque becomes equal to torque from the magnetic forces, the Flappermoves back to centered position. Then the gab between the Nozzles and the Flapperand the pressure at both spool ends will be the same. The spool stops at the positionwhere the torque of the feedback spring is alike the torque induced by the appliedcurrent to the coil.

Function MFB Valve


MFB - Advantages

¤ 2 stage design with dry torque motor¤ Low friction double nozzle pilotstage¤ High spool control forces¤ High dynamics¤ Replaceable pilot stage filter¤ Rugged and long-life design¤ High resolution, low hysterese¤ Completely set up at the factory¤ Optional fifth port for separate pilot supply¤ Low power consumption¤ Precise axis cut


MFB - Family

D630 Series

77 Series

G631 Series

G761 Series

78 Series

72 Series

0062 Series


MFB - Comparison

D630

G771

072

D062

G631

G772

G773

G761

Manifold Max Pressure Flow Rate

Standard katalog values

ISO 10372-04-04-0-92

ISO 4401-05-05-0-94

ISO 10372-06-05-0-92

ISO 10372-04-04-0-92

Moog Norm

ISO 10372-03-03-0-92

Moog Norm

ISO 10372-04-04-0-92

3000 psi / 210 bar 19 l/min -> 38 l/min

3000 psi / 210 bar 4 l/min -> 10 l/min

3000 psi / 210 bar 57 l/min

4 l/min -> 63 l/min

Port P,X,A,B

4500 psi / 315 bar

4000 psi / 280 bar

4500 psi / 315 bar 5 l/min -> 75 l/min

3000 psi / 210 bar 95 l/min -> 230 L/min

3000 psi / 210 bar 10 l/min -> 40 l/min

at 70 bar Delta P

05 l/min -> 40 l/min


MFB - Comparison

Rated Flow *1

Dynamic Hz *2

95

40

5

*1) Q at 70 bar Delta P. *2) 210 bar and 90° Phaseangle and +/- 40% Sig *3) 280 bar and 90° Phaseangle and +/- 40% Sig *4) 210 bar and 90° Phaseangle and +/- 25% Sig

200100 15050

D630-S *3

G771

G772G773

D062*4 G761-H38

G761-S63

G761-H04

80

230

G631*4

072

G761-H19G761-H10

D630-S *3

l/min


MFB - Comparison

Hz at 90° Phaseangle *1 Hz at -3db Amplitude *3*1) At 210 bar ; 90° Phaseangle ; +/- 40% Signal *2) At 210 bar ; 90° Phaseangel ;+/- 25 Signal*3) At 280 bar ; -3 dBAmplitude ; +/- 40% Signal *4) At 210 bar ; 90° Phaseangel ;+/- 25 Signal

G771

072-

*2 D062

*2 G631

200100

G772G773

G761

200100

*3 D630

Typical dynamic characteristics (standard valves)


MFB - Comparison

l/min

G771

072-

D062

G631

7515

G772G773

G761

D630

Rated Flow at 70 bar Delta P

23090604530l/min

160


MFB - Applications

62 / D062 Low performance position controlD631 dddD630 Pilotstage for Proportional valvesG760 / G761 Material Testing, Turbine, SimulatorsG77X Turbine78 Wood, Old flight simulators72 Steel Mills, Mat. Testing


MFB - Interface

4-Port valve / ISO 10372 / ISO 4401

Hydraulic Interface

Detailed information see individual catalogs

Manifold example

Standard Manifold


MFB - Interface

Hydraulic Interface

External Pilotsupply

5-Port valve / ISO 10372 / ISO 4401

Manifold example

Use of External 5 Port¤ The Pilotstage (Torque Motor) can

be separatly supplied from themainstage.

Advantages of the fifth Port¤ Increasing the danymic and the

spool control force due to a higherpilotspressure.

¤ Additional filtration for Piltostagepossible.

¤ For Failsafe condition thePilotstage can be controlled by anexternal solinoid valve.Detailed information see individual catalogs


Electrical Interface

Detailed information see individual catalogs

Valve

Co nnect or

Valve

Co nnect or

Valve

Co nnect or

4 Pin Valve Connectorse.g.: 4 Pin MIL-C-5015/14S-2S

Coils wire leads are available at theconnector allowing for single, series,or parallel connections

MFB - Interface


MFB - Family

D630 Series

77 Series

G631 Series

G761 Series

78 Series

72 Series

0062 Series

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