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