Function introduction:
The electro-hydraulic control actuator is equipped with two sub-systemsof electro-hydraulic proportional control remote control and on-site manualoperation. Electro-hydraulic proportional control system can be set accordingto the PLC control cabinet, regulation and off valve Angle and the Angle of thespeed of controllable scope, the proportional solenoid directional valve andangular distance sensor (encoder) to form a feedback loop, control accuracy canreach 0.2‰, and is equipped with a control cabinet on-site operation function,accumulator has enough volume to open and close the valve once without a hydraulic source; The hand pump operating system can openor close the butterfly valve using the hydraulic hand pump in the case ofsystem power failure and loss of pressure.
1 Composition and performance of electro-hydraulic actuator
The electro-hydraulic actuator is generallycomposed of four parts: the hydraulic actuator, the proportional controlcircuit (on-off is the solenoid valve control circuit), the hydraulic stationand the PLC control cabinet (on-off is the ordinary electric control cabinet).The explosion-proof control cabinet can be selected according to the workingconditions On the site.
1. Actuator
Theactuators of this system adopt the shift-fork type double-acting hydraulicactuators, with the daily working pressure of 12MPa and the maximum workingpressure of 16MPa.
1)Using high performance shifting forkmechanism, with its unique torque curve to drive most of the Angle stroke valvethe most ideal mechanism, its characteristics for large diameter valve toprovide a large opening torque; The guide bar can not only absorb the lateralforce of the fork mechanism but also correct the movement direction of thepiston rod. The bronze fork bushing and sliding block provide high mechanicalefficiency and extended service life.
2)Thehydraulic cylinder adopts high precision cold-drawn steel tube, which can bearthe maximum pressure above 31.5MPa. The surface of piston rod and guide rod is chrome plated and polished, which can effectively prevent corrosion and reduce friction resistance.The seal adopts imported y-type combination ring and PTFE+bronze combination guide, which makes the service life of the oil cylinder>.2 million times, thus greatly improving the service life of the actuator.
2.Controlloop system
Main components of the control system: block valve, hydraulic control one-way valve,globe valve, accumulator, electro-hydraulic proportional valve (on-off is theelectro-hydraulic directional valve), one-way valve, overflow valve, manualhydraulic pump, manual directional valve, precision filter (<20um, withblocking alarm function), Angle travel sensor (on-off is the limit switch).
3)Through the input signal of the proportional valve to adjust the valve'sswitching Angle and controllable speed Angle range, at the same time, theinternal sensor of the proportional valve will feedback the position signal ofthe slide valve and the position signal of the encoder to compare and correct,so as to get a more accurate valve position and controllable speed.
4)The on-offfunction of the electro-hydraulic actuator is to open and close the actuatorthrough the electro-hydraulic reversing valve. The speed of opening and closingthe valve can be adjusted by the speed regulating valve.
3. Hydraulic pump station
Maincomponents of the hydraulic station:
Oil tank (with oilfilling filter) manual pump (with directional control valve) overflow valve,pressure reducing valve, one-way valve, visible type oil level gauge, pressuregauge, hydraulic oil block, accumulator, oil return filter, hydraulic pump,motor, main filter with alarm device.
4. Local electrical control cabinet
1)PLC electrical control cabinet
A. It is composed of wiring terminal, PLC, signalamplifier, integrated circuit, transformer, etc
B. Controlcabinet panel with local/remote control, emergency cut off and self-lock buttonswitches
C. PLC controlcabinet function description:
a)If the button is switched to the remotefile, the valve can be opened and closed automatically according to the PLCsetting program through the external input of the valve control signal. If youswitch to manual shift, you can press the open or close button on the panel toopen or close the valve for in-place electric operation.
b)If the power should be cut offimmediately in an emergency, press the emergency cut off button. The switchlocks itself after disconnection. To restart the power supply, reverse thebutton switch to make it pop up, and then press the power switch to start it.
2)On-off electrical control cabinet :(configured underconditions where intelligent adjustment is not required)
A. The controlcabinet panel is equipped with buttons for emergency local operation, indicatorlight for valve position, alarm light for valve failure and emergency cut-offswitch.
B. Theindicator of valve position shows the current state of the valve, and theopening valve light is on, indicating that the valve is in the open state.Similarly, the closing valve light is on, and the valve should be in the closedstate.
C. Valveposition fault light: indicating valve stuck or hydraulic system failure, needmaintenance.
D. Emergencycut-off switch: press this switch, the control cabinet will automatically cutoff the power supply, making the system stop working instantly.
E. Valveopening button: press this switch and the valve will be opened in place.
F. Close thevalve button: press this switch and the valve will be closed in place.
G. Local/remoteswitch handle: switch to local operation file, and the valve can be operated inplace; Switch to remote file, you can control the valve by remote signal.
II Operating principle and method of electro-hydraulic actuator
1. Principle of hydraulic pressure
Actuator hydraulic working principle(Refer to drawing 1):
1)Switch valveand valve opening adjustment: make two 2/3 open solenoid directional valve1ya-1 and 1ya-2 solenoid coils energized at the same time to close the bypassoil circuit. At this point, the proportional solenoid valve can accept 4 ~ 20mAcontrol signal to open the actuator to the corresponding Angle, and accordingto the feedback signal of the encoder Angle correction, constitute a closedcontrol loop, to achieve the valve positioning accuracy. 4 ma signal valve isfully closed, 20mA signal valve is fully open, any signal between 4 and 20mAcorresponds to a positioning valve Angle;
Note: the design mode of two 2/3 through solenoid valves in seriesis to minimize the interference to the normal operation of the system if one2/3 through solenoid valve fails.
2)Emergencyquick opening valve due to power loss: if two 2/3 solenoid valves 1ya-1 and1ya-2 lose power at the same time, the solenoid valve by-pass oil path opens,and the high pressure oil of the accumulator passes through the logic valve todrive the hydraulic actuator to open quickly. Valve opening time ≤1S;
3)Automaticpressure filling function of the accumulator: when the system pressure is lowto the set value of the oil pump on the PLC control panel, the system startsthe motor to fill the pressure of the accumulator. When the system pressurereaches the set value of the oil pump on the PLC control panel, the motor stopsand the system pressure is completed.
4)Emergencyhand pump operation: close the high pressure ball valve 10-1, 10-2, put themanual reversing valve on the hand pump 9 on the left position, shake the handpump, the valve closes; Put the manual reversing valve on hand pump 9 on theright position, shake the hand pump and open the valve.
2. Operation instructions and precautions for electro-hydraulic actuator
1)Inject clean hydraulic oil (preferably after filteringwith 20 micron filter core) into the oil inlet of the hydraulic station. It isadvisable to fuel up to about 2/3 of the oil tank. The fluid should bedeposited for one to two hours after injection, allowing it to naturallyrelease air from the oil. Hydraulic oil most avoid dirty deterioration, so 3-6months should be replaced, and clean the tank.
2)Beforeconnecting the hydraulic pipeline between the hydraulic execution structure andthe hydraulic station, if the seamless steel pipe is used, it must be picklingto remove the residue in the pipe, so as to prevent contamination and blockageof the components in the hydraulic system.
3)Checkwhether the manual reversing valve in the manual pump system is in the middleposition and the manual system is in the closed state before starting the motorpower of the hydraulic station
4)Switchon the power and start the hydraulic pump. The hydraulic pump needs no-loadpreheating for 20 minutes before reversing test. EH hydraulic oil oil suitableworking temperature: 30-55ºC(Note: observe the oil temperature at any time duringthe test, and stop the operation when the oil temperature exceeds 60ºC. Operateonly when the oil temperature is cool to prevent damage to the system seal.)
5)Electriclocal operation: press the "remote /local" button on the controlcabinet to the local operation position, then press and hold the "open"button on the touch screen, and gradually open the valve; Press and hold the"close" button to close the valve. Note:after the hydraulic system is connected to the actuator for the first time, thevalve should be repeatedly opened and closed several times in the wholeprocess, so as to eliminate the air in the hydraulic pipeline. Duringoperation, the tank cursor should be observed at all times, and the oil shouldbe filled to 2/3 of the tank immediately when the oil is below 1/2of the volume.
6)Remoteoperation: push the remote control button on the control cabinet to the remotecontrol position, then the valve can be opened or closed by input 4-20macontrol signal, and the size of 4-20mA control signal can be changed toaccurately control the valve position opening
7)Manual pump operation in case of powerfailure: cut off the power supply of the hydraulic station, open the twohigh-pressure ball valves beside the manual pump (the handle is parallel to thebox cover), position the red handle on the hydraulic manual pump in theposition of pressing down, and then pressurize the long handle of the pump bypulling it up and down; Turn the red handle on the manual reversing valve toreverse the oil flow and open and close the butterfly valve. (note: when themanual reversing valve handle is in the middle, the valve is positioned).
8)Afterthe operation of the emergency manual pump system, the manual reversing valvemust be placed in the middle in time to prevent mutual interference duringelectric operation.
9)Accumulatorfunction: the accumulator plays a role in this system to maintain the stabilityof oil line working pressure and enough to open or close the valve once whenthe hydraulic power source is lost.
10)Emergency cut-off operation: press the red emergency cut-off button onthe control cabinet panel to cut off the power supply of the hydraulic systemand the valve will stop immediately. If you want to restore theworking state, you need to reverse rotate the red cut off button, make it popup, and then press the power button on the side to start it.
11)HPUis equipped with precision filter. If the alarm indicator is on, the internalfilter element should be replaced or cleaned in time to ensure the normaloperation of the hydraulic system.
3.Assembly diagram of hydraulic actuator and hydraulic pump station
