Iyappan Engg Products

HP BYPASS SYSTEMHP BYPASS SYSTEM

SERVO VALVES - ST 10/4, ST-10/63

SERVO VALVES - ST 10/4, ST-10/63

BLOCKING ELEMENT BL 10

BLOCKING ELEMENT BL 10

HYDRAULIC ACTUATOR ASM

63, 100, 160, 200 250

HYDRAULIC ACTUATOR ASM

63, 100, 160, 200 250

STEPPING CONTROL APL-6

STEPPING CONTROL APL-6

QUICK STROKING DEVICE SSB-10

QUICK STROKING DEVICE SSB-10

OIL SUPPLY UNIT

OIL SUPPLY UNIT

FEEDBACK TRANSMITTER


electro hydraulic servo valves...

Electro Hydraulic Servo Valves

Servo Valve -Feedback Mechanism

- An Introduction

COLD WATER

HOT WATER

- A person wants to take bath.

- He opens both the control valves of hot water & cold water

- He feels the temperature

- He is not comfortable with it


Electro Hydraulic Servo Valves- An Introduction

HOT WATER

- His brain gives feedback to his hands

- And his hand in turn adjusts the valves

- This process continues until he feels comfortable

COLD WATER


Electro Hydraulic Servo Valves- An Introduction

- He is satisfied and continues to have bath.

HOT WATER

COLD WATER

Electro Hydraulic Servo ValvesSimple Servo Valve Feedback System

BLOCK DIAGRAM OF SERVO FEEDBACK MECHANISM

CHENNAI - 600 098IYAPPAN ENGINEERING INDUSTRIES PVT LTD

VALVE

INPUT ERROR

LOAD

OUTPUT

+-HYD. CYLINDER

ORHYD.MOTOR

PUMP

FEEDBACK


Electro hydraulic Actuator System - Continuous Control


Servo System - Uses

- POSITION CONTROL

- PRESSURE CONTROL

- SPEED CONTROL

- TEMERATURE CONTROL

Servo system is used for

Electro Hydraulic Servo ValvesServo Valve - Applications

• CONTROL VALVES

• ROBOTS

•PLASTIC INJECTION MOULDING MACHINES

•AUTOMATIC GAUGE CONTROL FOR STEEL ROLLING MILLS

•DEEP SEA RESEARCH MANIPULATOR

•SIX AXIS MOTION SYSTEM FOR FLIGHT SIMULATOR

•STEERING SYSTEM FOR SHIP

•HONING MACHINE & MACHINE TOOL INDUSTRIES

•TESTING MACHINES

Electro Hydraulic Servo ValvesServo Valve - STAGES

Servo valve consists of 2 stages

SERVO VALVE

FIRST STAGE

SECOND STAGE

HYDRAULICELECTRICAL






blocking element...

Blocking Element

Blocking Element

maintenance of servo valves...

Importance of oil cleanliness :

Hydraulic oil should conform to NAS Grade -6 for the following reasons:

1. The control oil has to pass through 0.17mm & 0.25mm diameter orifices - any blockage will cause malfunction of the system.

2. The diameter clearance between the Spool & Bush is 6 to 8 microns.

- any dirt will cause scoring mark on the Spool & the Bush.- the Spool may also get stuck

Maintenance - Servo Valves

Servo Valve

Servo Valve

Servo Valves

Servo Valve

Servo Valve

Servo Valve

Servo Valve

Servo Valve

Servo Valve

Servo Valve

SL.NO.

FAULTS PROBABLE CAUSES REMEDIES

1 Actuatormoves in onedirection

a)b)

c)d)

In spool dia. 0.25 holeblocked.Throttle Pin dia.0.17hole blocked.Balancing of R6zdisturbedTorque Motor & R6zstruck up.

a)b)

c)d)

Clean the spool Clean the throttlepin

Balance the R6zClean it by Air

2 Actuator notmoving inboth directions

a)

b)

c)

d)

Spool wrong assy.

In spool dia.0.25 holeblocked in both sidesTorque Motor Rotarypart stuck up.Connecting wires areloose and discontinued

a)

b)

c)

d)

Assemble the spoolcorrectly.Clean the spool

Clean it by air

Correct the wiringand loads properly.

Trouble shooting of Servo Valves

SL.NO.

FAULTS

PROBABLE CAUSES

REMEDIES

3 a) 3b) 3c) 3d) 3e)

Oil Leak through Filter Support Oil leak through Torque Motor Oil leak through Manual Cover Assembly Oil leak through Stud Coupling side Oil leak through Servo Valve Face side

a) b) c) a) b) a) b) a) b) c) a)

'O'Ring flat or damaged Scoring mark on dia.17.5 of Filter Support or Filter Support damaged Housing bore of Filter Support hole damaged Diaphragm damaged 'O'Ring flat or damaged Cover 'O'Ring or Piston, 'O'Ring damaged Scoring Mark on Cover Assy. ID or OD Hose, 'O'Ring damaged Stud coupling Broken or damaged Hose connection damaged Face 'O'Ring flat or damaged

a) b) c) a) b) a) b) a) b) c) a)

Change 'O'Ring Change Filter Support Change the valve Change the Diaphragm Change the 'O'Ring Change the 'O'Ring Change the Cover Assembly. Change the 'O'Ring Change the Stud Coupling Change hose Change the 'O'Ring


SL.NO.


4. Irregularoperation

a)

b)

Electrical connectingplug loose

Discontinuity of supply

a)

b)

Correct the connection

Check and correct thesupply.

5. Spool jammedand rusted

a)

b)

Oil contamination

Water mixed in the oil

a)

b)

Change the Servo valve

Clean the oil

Change the oil (send theservo valve to Factory forservicing.


maintenance of blocking elements...

Blocking Element - Maintenance



SL.NO.


1. Irregular operation a)

b)

Electrical Plug loose

Discontinuity of ElectricSupply

a)

b)

Correct theconnectionCheck and correct theElectric supply

2. Valve opening andActuator drifting

a)

b)

c)

Piston 'O'Ring damaged

Pistron Struck-up.

Solenoid Valve notfunctioning

a)

b)

c)

Change the 'O'Rings

Service and clean thePiston & bore

Check & servicesolenoid valve. (Ifproblem continues,change the solenoidvalve)

3. Oil leak throughManual Cover Assy.

a)

b)

Cover & Piston Rod'O'Ring damaged

Cover OD or Piston RodOD damaged

a)

b)

Change the 'O'Ring

Change the ManualCover Assy.

4. Oil leak throughSpring Cover Assy.

a)

b)

Spring Cover, 'O'RingdamagedImproper seating ofCover Assy.

a)

b)

Change the 'O'Ring

Correctly assemblethe Spring CoverAssy.

TROUBLE SHOOTING OF BLOCKING ELEMENT

SL.NO. FAULTS PROBABLE CAUSES REMEDIES5. Oil leak through

Solenoid ValveConnecting Plate

a)'O'Rings of Solenoid ValveConnection face damaged

a) Change both 'O'Rings

6. Oil leak through the faceof the ConnectingManifold and face of theBlocking Unit

a)

b)

c)

Face 'O'Rings damaged

Improper seating of ServoValves, Blocking Element onConnecting Manifold

Threads of connectingManifold damaged

a)

b)

c)

Change the 'O'Rings

Correct and properlyassemble the Servo Valve& Blocking Element onthe connecting Manifold

Change connectingManifold

7. Piston Jammed a)

b)

Piston rusted

Mix up of water in the oil

a)

b)

Change the BlockingElement (Send theBlocking element forservicing)Change Oil

TROUBLE SHOOTING OF BLOCKING ELEMENT

oil supply unit...

OIL SUPPLY UNIT

OIL SUPPLY UNIT

OIL SUPPLY UNIT

OIL SUPPLY UNIT

OIL SUPPLY UNIT

OIL SUPPLY UNIT

OIL SUPPLY UNIT

hydraulic actuator...

ACTUATOR

ON OF F CONTROL ASSY

QUICK STROKING ASSY

feedback transmitter...


Feedback Transmitter

electro hydraulic actuator…

Electro Hydraulic Actuator


Iyappan Engg Industries Pvt Ltd


Iyappan Engg Industries Pvt Ltd

List of Tests Conducted for E.H.AEHA. TESTS - FINAL STAGE

(FULLY ASSEMBLED)

OIL TANK PRE. TEST1

CYLINDER ASSY. PRE.TEST

2

HAND PUMP ASSY. TEST4

SAFETY VALVE ASSY. TEST

5

SHUT OFF VALVE ASSY. TEST

6

PRESSURE FILTER ASSY. TEST

7

DIFFERNTIAL PRESSURE ASSY. TEST

7a

CHECK VALVE ASSY. TEST

8

9 TOP PLATE ASSY. TEST


TEST

10

3 TANK & CYLINDER ASSY. TEST

List of Tests Conducted for E.H.A









ASSEMBLY CYCLIC TEST

All the assemblies are tested for a cyclic test for 3 days in our Test Bench for the total stroke length at 54 cycles per minute. Totally 10000 cycles in operation before taking out the final reading as per the data given.

SL.NO. IY-14STROKE 40MM

BEFORE STARTING THE CYCLE TEST

SERVO VALVE INPUT (mA)

TRAVEL OF PISTON UPWARD

(mm)

TRAVEL OF PISTON

DOWNWARD (mm)

OUTPUT OF FEEDBACK

TRANSMITTER - UPWARD (mA)

OUTPUT OF FEEDBACK

TRANSMITTER - DOWNWARD

(mA)4.00 0.00 0.00 4.00 4.016.00 5.12 5.18 5.97 6.008.00 10.33 10.50 7.97 8.04

10.00 15.65 15.80 10.13 10.1712.00 20.47 20.60 12.07 12.1114.00 25.44 25.48 14.02 14.0616.00 30.41 30.48 16.00 16.0318.00 35.25 35.30 17.94 17.9620.00 40.15 40.15 19.94 19.94

CONCLUSION: Hysterisis in Travel - 0.17mmHysterisis in Feedback - 0.07mA

IYAPPAN ENGINEERING INDUSTRIES PRIVATE LIMITED: CHENNAI-600098

TYPE TEST FOR EHA

GRAPH PLOTTED BEFORE STARTING THE CYCLE TESTInput Current vs Piston Travel (Sl.No.IY-14, Stroke - 40mm)

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

0.00 5.00 10.00 15.00 20.00 25.00

Input Current (mA)

Pis

ton T

ravel (

mm

)

TRAVEL OF PISTON UPWARD (mm) Piston down (mm)

GRAPH PLOTTED BEFORE STARTING THE CYCLE TESTInput Current vs Feedback Transmitter Output

(Sl.No.IY-14, Stroke - 40mm)

0.00

5.00

10.00

15.00

20.00

25.00

0.00 5.00 10.00 15.00 20.00 25.00

Input Current (mA)

Feedback

Tra

nsm

itter

Outp

ut (m

A)

OUTPUT OF FEEDBACK TRANSMITTER - UPWARD (mA)

OUTPUT OF FEEDBACK TRANSMITTER - DOWNWARD (mA)

SL.NO. IY-14STROKE 40MM

SERVO VALVE INPUT (mA)

TRAVEL OF PISTON UPWARD

(mm)

TRAVEL OF PISTON

DOWNWARD (mm)

OUTPUT OF FEEDBACK

TRANSMITTER - UPWARD (mA)

OUTPUT OF FEEDBACK

TRANSMITTER - DOWNWARD (mA)

4.00 0.00 0.00 3.98 3.976.00 5.12 5.12 5.93 5.928.00 10.24 10.35 7.87 7.90

10.00 15.48 15.61 9.97 10.0312.00 20.60 20.75 12.04 12.0914.00 25.65 25.75 14.02 14.0416.00 30.58 30.72 16.00 16.0518.00 35.48 35.58 17.94 17.9720.00 40.20 40.20 19.94 19.94

CONCLUSION: Hysterisis in Travel - 0.15mmHysterisis in Feedback - 0.06mA

AFTER COMPLETING 10000 CYCLES

IYAPPAN ENGINEERING INDUSTRIES PRIVATE LIMITED: CHENNAI-600098

TYPE TEST FOR EHA

GRAPH PLOTTED AFTER THE CYCLE TEST Input Current vs Piston Travel (Sl.No.IY-14, Stroke - 40mm)

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

0.00 5.00 10.00 15.00 20.00 25.00

Input Current (mA)

Pis

ton

Trav

el (m

m)

TRAVEL OF PISTON UPWARD (mm) TRAVEL OF PISTON DOWNWARD (mm)

GRAPH PLOTTED AFTER THE CYCLE TEST Input Current vs Feedback Transmitter Output

(Sl.No.IY-14, Stroke - 40mm)

0.00

5.00

10.00

15.00

20.00

25.00

0.00 5.00 10.00 15.00 20.00 25.00

Input Current (mA)

Fee

dbac

k Tr

ansm

itter

Out

put

(mA

)

OUTPUT OF FEEDBACK TRANSMITTER - UPWARD (mA)

OUTPUT OF FEEDBACK TRANSMITTER - DOWNWARD (mA)

ELECTRO HYDRAULIC ACTUATORASSY. (MODEL HSA-1-K-02)

SECTIONAL VIEW

MODIFIED ELECTRO HYDRAULIC ACTUATOR ASSEMBLY.

02

01

4-PD-E5(1)-SPEC-0064-PD-E5(1)-SPEC-006

MODIFIED ITEMS:-

SECTIONAL VIEW OF EHA - HSA-1-K-02

IYAPPAN ENGG. INDUSTRIES PVT.LTD.

HYDRAULIC CIRCUIT DIAGRAMFOR E.H.A MODEL HSA-1-K-02

4-PD-E5(1)-SPEC-0054-PD-E5(1)-SPEC-005

M

m

HYDRAULIC CIRCUIT DIAGRAM OF EHA - HSA-1-K-02

COMBINED PRESSURE RELIEF AND CONTROL VALVE ASSEMBLY

COMBINED PRESSURE RELIEF AND CONTROL VALVE ASSEMBLY

SL.NO.


1) Pressure gauge not working 1) Change the pressuregauge

2) Insufficient oil in sump 2) Fill oil upto sight glasslevel

3) Leak in pressure line 3) Tighten up allconnections(Check for pipe fractureif require change)

4) Suction Filter clogged 4) Clean the filter5) a)

b)

Motor Running inwrong direction or twophase supply

Defective Motor

5) a)

b)

Correct the supplyand direction as perthe indication mark.

Replace the Motor6) Coupling between Motor and

pump defective6) Replace the coupling

7) Pump not pumping oil 7) Replace Pump (send thepump for servicing)

8) Pressure limiting valveincorrectly adjusted

8) Adjust the pressurelimiting valve correctly

I Oil pressuregauge indicateslittle or no oilpressure

9) Accumulator Safety Blocknot working properly

9) Change the Safety Block(Send the Safety Blockfor servicing

TROUBLE SHOOTING OF ELECTRO HYDRAULIC ACTUATOR

SL.NO.


1) Feed Back Spring orRetaining spring of the Servovalve damaged

1) Replace the spring andreadjust the range

2) Feed back rod not rigidlysecured

2) Tighten and secure thefeed back rod correctly.

3) One Restrictor blocked 3) Clean the restrictor withcompressed air.

4) Dirt between flappor and oneof the nozzle

4) Clean the Nozzle

II Piston moves toone end andremainsstationary

5) Leakage in oil line tocylinder

5) Tighten oil lineconnection and to be leakfree

1) Change the ambienttemperature in over a widerange, ie. Between summerand winter

1) The displacement canonly be in the order of3% and should becorrected by means offine adjustment screw

III The stroke of theactuator shifts

2) Iron particles between thepole shoes

2) Clean the pole shoesarmature and magnet.


SL.NO.


1) Filter element blocked 1) Clean the Filter.IV Stroke time forthe operatingrange too long

2) More Load on the Actuator 2) Deflect the servo valvefully and note pressuregauge reading. Thismust always fall. Themaximum workingpressure atleast 3 barbelow the set oilpressure.

Hand pump isnot operative

Hand pump blocked due to dirt inreturn flow restrictor

Clean the restrictor

1) Pressure filter choked 1) Clean the filter2) Blockage in Nozzle of

Restrictor assy.2) Clean the Nozzle of

restrictor assy.

V Hunting of theActuator

3)

4)

Feed back spring andRetaining spring mounting isimproper and springtouching the body.

The pressure on both side ofthe flapper is not equal.

3)

4)

Mount the springsproperly. If required,change the Feed BackSpring

To send to Factory forcaliberation.


SL.NO.


1) Wiper seal damaged 1) Change the wiper sealVI Oil leakage inPiston Rod 2) Cylinder seat 'O'Ring

damaged2) Change the 'O'Ring

VII Oil leakage insight glassmounting

Gasket damaged Change the Gasket

1) Shut-off valve not open 1) Open the shut off valve2) 4/3 way valve or movable

plate set for incorrectdirection

2) Set 4/3 way valve tocorrect direction

3) Non-return valve to pumpdoes not close andAccumulator oil is forcedthrough Pump

3) Change the Non-returnvalve

VIII Accumulator notoperating duringpower failure

4) Leakage in oil pipe 4) Correct the oil lineIX During Power

failure theActuator notoperating to fullstroke

1)

2)

Oil in the Accumulator islow due to Nitrogen gaspressure is highAccumulator envelopdefective

Correct the Nitrogen gaspressure in the Accumulatorby charging.

Change the Accumulator(Return the defectiveAccumulator to theManufacturer for repair)


SL.NO.


X Accumulatoroperates slowly

Load on Actuator too great Discuss with manufacturer.Possibility of increasing oilpressure

XI Irregular feedback from theFeed BackTransmitter

1)

2)

Feed Back TransmitterStem Struck up.

Guide plate dislocated

1)

2)

Clean the stem (ifrequired change the FBT

Correct the guide plateand mount correctly.


IYAPPAN ENGINEERING INDUSTRIES PRIVATE LIMITED: CHENNAI-600 098

IMPROVEMENT DONE ON EHA FROM THE FEED BACK

Sl.no.

Description of item Earlier used Used atpresent Improvement

1 Tank Alumionium sand casting Aluminium fabricated out of platesand anodized

Contamination from the casting iscompletely eliminated

2 Internal Pipelines Seamless Steel carbonSteel Tube

SS Tube after acid cleaning is used This prevents contamination of particlesfrom the pipelines

3 Feed Back Transmitter Linear variable Transmitterwith cam was used

Direct mounting imported SiemensAngular Transducer is used

Avoided all linkage mechanism and playis completely removed . Now, Hysterisisis found less and repeatability is good

4 'O'Rings and seals Nitrile was used Viton O rings and seals are used Withstanding higher temperature5 D P Switch Differential pressure gauge

of Indian make was usedClogging indicator imported fromMAHLE-GERMANY is used

More accurate and compact. Damageduring transit of pressure gauges avoided

6 Motor 0.25 KW 0.33KW Tripping is totally avoided and heating ofthe motor is reduced.

7 Hand pump operation Suction was less Suction Area was increased. Suction was increased and it takes only25 strokes instead of 45 strokes takenearlier for the movement of Actuator for40mm.

8 Tests Only assembly test andfinal test was conducted

Assembly stage inspection wasintroduced and all the actuators areindividually checked cyclically for10000 times

After cyclical tests repeatability ischecked and found well within the limitincluding hysterisis.

NOW, FOR THE NEW SERIES UNDER DEVELOPMENT, FOLLOWING WERE INTRODUCED.

1. Double filteration system - this enables to change the filter during the operation without stopping the actuator.

2. Tandem Pump with combined pressure relief valve is used- this reduces volume of pressurised oil and hence, heat generated is less during idlecondition..

3. Yoke length is increased. This reduces conduction of heat from the valve of the actuator.

FINALLY TO CONCLUDE, ALL THE DIFFICULTIES WERE OVERCOME AND NOW THE EHA IS PERFORMING VERY WELL.

IMPORTANT POINTS TO NOTE

1. Electro Hydraulic Actuator Assembly is selective assembly.

2. Spool is not interchangeable

3. Spool is to be fit in correct direction only

4. Oil contamination to be maintained to NAS 6 level

5. While dismantling the nozzle, care should be taken to reassemble in the same position and also locking screw position should not be disturbed.

ELECTRO HYDRAULIC ACTUATOR

bypass limit controller...

Bypass Limit Controller

Bypass Limit Controller

electro hydraulic converter...

Electro Hydraulic Converter

Electro Hydraulic Converter

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Iyappan Engg Products