Post on 04-Jun-2018
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Festo Didactic GmbH & Co. Electrohydraulics
Electrohydraulic press
Motor with hydraulic pump Control panel Valve manifold CylinderThe hydraulic press is controlled via the electrical control panel.
Electrical signals are used to activate the valves in the hydraulic installation.
The electrohydraulic press is used to form rectangular troughs.
Control pane
Motor withhydraulic pump
Valve manifold
Actuator(cylinder)
Function units
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Festo Didactic GmbH & Co.
Electrohydraulic press
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Festo Didactic GmbH & Co. Electrohydraulics
Schematic layout of an electrohydraulic installation
Division of installation into signal control section and hydraulic power section.
Input and processing of electrical signals.
Solenoid valves form the interface between the electrical signal control section and
the hydraulic power section.
Controls the flow of hydraulic fluid by means of solenoid valves. Actuators convert
hydraulic energy into motions.
Signal control section
Signalinput
Hydrauliccylinder
Solenoidvalve
Hydraulicpowersupply(conversion)
Powersupply
Signalprocessing
Power sect on
Signal control section
Hydraulic power section
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Schematic layout of an electrohydraulic insta
Signal control section
Power secti
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Festo Didactic GmbH & Co. Electrohydraulics
Electrical power supply unit
Connection to mains supply.
Supplies signal control section with specified or maximum voltage and current
values.
Voltage transformation Rectification Smoothing Stabilisation Fuse protectionIn mobile hydraulic systems, rechargeable battery systems or generators are used
as a power supply for the signal control section.
230VAC
24VDC
TR
50 C
G C T T
Transformer Rectifier Smoothing Stabilisation Fuse
Functions in
power supply unit
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Festo Didactic GmbH & Co.
Electrical power supply unit
TR G C T
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Festo Didactic GmbH & Co. Electrohydraulics
Electrohydraulic converters (solenoid valves)
Convert electrical signals into hydraulic switching operations.
The switching armature is drawn into the coil, which acts as a magnet.
This produces a displacement of the actuating piston in the hydraulic 4/2-way valve.
A B
P T
Switching armature
4/2-way solenoid valve
BT A P L
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Festo Didactic GmbH & Co.
Electrohydraulic converters (solenoid valv
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Festo Didactic GmbH & Co. Electrohydraulics
Dry solenoids
wet solenoids
The solenoid is separated from the hydraulic fluid; a seal is required on the stem.
Simple construction
The armature chamber of the solenoid is filled with hydraulic fluid, the solenoid
operates in oil.
Low friction Little abrasion Good heat dissipation Long service life
seal
Dry solenoid Wet solenoid
Dry solenoid
Advantage
Wet solenoid
Advantages
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Festo Didactic GmbH & Co.
Dry solenoid Wet sol
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Festo Didactic GmbH & Co. Electrohydraulics
Solenoid valve connections
Solenoid with plug base Cable with connector socketElectrical signals are transmitted via standard connectors.
Reliable alignment of connections Connections can be attached and detached quickly Protected against dust and water
2
1
3
Protective earth connection
Plug base
Electricalconnections
Connector components
Advantages
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Festo Didactic GmbH & Co.
Solenoid valve connections
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Festo Didactic GmbH & Co. Electrohydraulics
4/3-way solenoid valve
Valve spool is directly actuated by solenoids.
The piston spool is displaced to the right and creates the connections P A
and BT.
Rest position produced by spring centring of piston spool. All inputs of the 4/3-way
valve are closed in this position.
T A P B
T A P B
A
a b
B
P T
a
a
b
b
Actuation on left
Rest position
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Festo Didactic GmbH & Co.
4/3-way solenoid valve
a
T A P B
T A P B
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Festo Didactic GmbH & Co. Electrohydraulics
4/3-way solenoid valve, piloted
Direct activation of pilot spool via solenoids.
The pilot piston spool is displaced to the right, and hydraulic fluid is directed to the
right-hand side of the main control spool, creating the connections P A and BT.
Rest position produced by spring centring of pilot and main piston spools. All ports
of the 4/3-way valve are closed at the main valve.
Simplified symbol
P T
A
A
B
B
P T
PB AT
Detailed symbol
Actuation on left
Rest position
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Festo Didactic GmbH & Co.
4/3-way solenoid valve, piloted
PB AT
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