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Advance Electro-Hydraulics
Hand in assignments! Mid term test 2 weeks from now. Same day, time and place. CO1, CO2 and CO3 only (hydraulics, electro-hydraulics
and pneumatics) Good luck!
Before that…
Relevancy:
1. Used to build Continuous Cycle circuit.
2. Used to latch a circuit for continuous supply of electricity to a particular line.
3. Used when replacing a double solenoid valve to a single solenoid valve of a circuit, without changing the originality of the circuit function.
Memory Circuits
Types of Memory Circuits Memory ON (Dominant Set)
+24V
0V
ON
K1
K1
OFF
K1
• When ON is pressed, Relay coil K1 will be energized. Both relay K1 switches will close. This means, while the lamp turns on, the relay switch will continuously energize the coil. Therefore, the lamp is permanently on. Only when the OFF button is pressed, the lamp will switch off.
• To confirm that this is a Memory ON circuit, press both ON and OFF together. The lamp will still light ON.
Memory OFF (Dominant Reset)
Types of Memory Circuits
• The function of this circuit is similar to the previous Memory ON circuit. However, please note that the OFF button is placed below the ON button, not parallel!
• To confirm that this is a Memory OFF circuit, press both ON and OFF together. The lamp will NOT light ON.
+24V
0V
ON
K1
K1
OFF
K1
Proximity -> closeness Detect close objects without contact. Various types:1. Inductive sensor2. Capacitive sensor3. Optical sensor
Proximity Sensors
Inductive Sensor and Symbol
Used to sense only metal type of object.
Capacitive Sensor and Symbol
Used to sense only high density objects.
Optical Sensor and Symbol
Used to sense only reflective type of object.
Design of Advance Electro-Hydraulics Systems
More than 1 actuator1 cylinder needs 1 valveTips for circuit design:◦Identify sequence of movement◦Identify limit switch/sensor status
Multi Actuator Circuit
Example: A hydraulic actuated drilling machine
contains two double acting cylinders (DACs). When the work piece is located at its position, cylinder A will clamp the work piece. Then, the drilling process starts, where the spindle is controlled by cylinder B. After completion of drilling, cylinder B will retract to the initial position, before the clamping cylinder retracts.
Sequence: A (extend) -> B (extend) -> B (retract) -> A (retract)
Multi Actuator Circuit
Identify sequence of movement
Step 1: Sequence
A+ B+ B- A-
F=0 F=0
Cylinder A Cylinder BA 0 A 1 B 0 B 1
Make the group
A group must contain different elements 1 group represents 1 coil
Step 2: Grouping
A+ B+ B- A- K1 K2
Step 3: Limit switch/sensor status
Identify limit switch/sensor statusA+ B+ B- A-
A1 B1 B0 A0
F=0 F=0
Cylinder A Cylinder BA 0 A 1 B 0 B 1
<= Actions
<= Sensors
Step 4: Rephrase Rephrasing the sequence and limit
switch/sensor status A1 B0
A+ B+ B- A-
Start B1 A0
Right side of circuit
Left side of circuit
Designing of Hydraulic Circuit
Y1 Y4Y3Y2
A0 B1B0A1
2 coil for 2 groups
4 solenoid for Y1, Y2, Y3 & Y4
A+ K1 + Start + A0
Latching B+ K1 + A1
B- K2 + B1 K2 due to changing group
A- K2 + B0
END OF LECTURE