MT2351_Fluid Power Systems_ Unit-II

1. Unit-II DESIGN OF HYDRAULIC CIRCUITS
MT2351 FLUID POWER SYSTEMS
Prepared by:
Dr. P. Balasundar, M.E., Ph.D.,
Assistant Professor (Senior Scale),
Department of Mechatronics Engineering,
KAMARAJ College of Engineering and Technology.

2. DESIGN OF HYDRAULIC CIRCUITS
Accumulators, Intensifiers. Hydraulic circuits - Regenerative,
Pump Unloading, Double pump, Air-over oil, Sequence, Fail-
safe, Speed control, Electro hydraulic circuits.
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3. FLUID SYMBOLS
• A family of graphic
symbols has been
developed to represent
fluid power
components and
systems on schematic
drawings.
• https://www.valmet.com/media/articles/up-
and-running/reliability/FRFluidDwgs1/
• https://engineeringlibrary.org/reference/hydraul
ics-graphic-symbols-for-fluid-power-diagrams-
navy
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4. Accumulators
• Accumulator is a pressure vessel for
storing hydraulic pressure in it utilizing
compressible and de compressible nature
of fluid.
• So, it can be said that the accumulator has
a similar function to the rechargeable
electrical battery.
• The most common application for an
accumulator is supplementing the pump
flow in a hydraulic system in which a high
flow rate is required for a brief period of
time.
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5. Types of Accumulators
1. Weight loaded accumulator
2. Spring loaded accumulator
3. Gas charged accumulator
4. Piston type
5. Bladder type
6. Diaphragm type
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6. Types of Accumulators
1. Weight loaded accumulator
2. Spring loaded accumulator
3. Gas charged accumulator
4. Piston type
5. Bladder type
6. Diaphragm type
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7. Applications of Accumulators
1. Accumulator as
leakage compensator
2. Accumulator as
auxiliary power
source
3. Accumulator as
emergency power
source
4. Accumulator as
hydraulic shock
absorber
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8. Applications of Accumulators
1. Accumulator as
leakage compensator
2. Accumulator as
auxiliary power
source
3. Accumulator as
emergency power
source
4. Accumulator as
hydraulic shock
absorber
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9. Applications of Accumulators
1. Accumulator as
leakage compensator
2. Accumulator as
auxiliary power
source
3. Accumulator as
emergency power
source
4. Accumulator as
hydraulic shock
absorber
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10. Applications of Accumulators
1. Accumulator as
leakage compensator
2. Accumulator as
auxiliary power
source
3. Accumulator as
emergency power
source
4. Accumulator as
hydraulic shock
absorber
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11. Applications of Accumulators
1. Accumulator as
leakage compensator
2. Accumulator as
auxiliary power
source
3. Accumulator as
emergency power
source
4. Accumulator as
hydraulic shock
absorber
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12. Pressure Intensifier
• Pressure Intensifier = Pressure Booster
• Devices used to generate pressure
greater than those achievable with
standard hydraulic pumps alone.
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13. Intensifier Circuit – Punching Press
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Punching Operation Both Clamping & Punching Operation

14. Industrial Circuits
• Regenerative circuit
• Sequence
• Automatic cylinder reciprocating system
• Synchronization
• Fail-Safe
• Pressure Intensifier
• Air-over oil
• Pump Unloading
• Double- Pump
• Speed Control
• Hydrostatic transmission
• Electro hydraulic circuits
• Mechanical hydraulic servo systems
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15. Air-over-oil intensifier circuit
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16. Some Sample Hydraulic Circuits
• Circuit 1 : Simple Cylinder
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17. Some Sample Hydraulic Circuits
• Circuit 2 : Simple Cylinder- Shuttle Valve Circuit
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18. Some Sample Hydraulic Circuits
• Circuit 3 : Hydraulic Motor
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19. Some Sample Hydraulic Circuits
• Circuit 4 : Pressure Reducing Valve – Operating two cylinder with variable Pressure
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20. Some Sample Hydraulic Circuits
• Circuit 5 : Sequence Valve
– Operating two cylinder in
required sequence by using
pressure
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21. Industrial Circuits – Regenerative Circuit
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• It is used to speed up the extending
speed of the double acting cylinder.
• The speed of extension in the
regenerative circuit is greater than
that for a regular double acting
cylinder.
• But the speed of retraction is similar
to the regular double acting cylinder.
• This is because oil flow from the rod
end regenerates with the pump flow
to provide a total flow rate, which is
greater than the pump flow rate to
the blank end of the cylinder.

22. Industrial Circuits – Sequencing Cylinder Circuit
• Circuit 5 : Sequence Valve
– Operating two cylinder in
required sequence by using
pressure
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23. Industrial Circuits – Automatic Reciprocation Circuit
• The sequence valves can also be used
to produce continuous reciprocation
of a hydraulic cylinder.
• This can be achieved by using two
sequence valves and a pilot pressure
operated spring-centered 4/3 DCV.
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24. Industrial Circuits – Synchronization Circuit
• To accomplish the identical task from
the cylinders at the same rate,
synchronizing circuits are employed.
• This is achieved by using double-end
cylinders in series.
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25. Industrial Circuits – Fail-safe Circuit
• Fail-safe circuit is designed to
safeguard the operator, the machine
and work piece.
• These circuits prevent any possible
injury to the operator or damage to
the machine and the work piece.
• It is also called as two handed safety
circuit.
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26. Industrial Circuits – Pump Unloading Circuit
• Replaces pressure relief valve with
unloading valve.
• Unloading valve is used to unload the
pump.
• Unloading valve unloads pump at ends
of each extension/retraction
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27. Industrial Circuits – Speed Control Circuit
• Achieves with pressure compensated
flow control valve.
• DCV is used to control the rotational
direction of motor.
• Pressure compensated flow control
valve is used to control speed of the
motor.
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28. Industrial Circuits – Double Pump Circuit
• Uses two pumps – High Pressure Low
flow pump and Low pressure high flow
pump together
• Eliminates necessity of High Pressure
and High flow pump which is too high
in cost.
• Check Valve is for protecting high
pressure pump on low pressure pump
while return.
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29. Meter In Vs Meter Out Circuits
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Meter In Circuit Meter Out Circuit

30. Industrial Circuits – Mechanical Hydraulic Servo
System Circuit
• Uses Mechanical controlled Servo Valve
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31. Industrial Circuits – Hydrostatic Transmission Circuit
• Uses Closed Circuit Drive
• Exhaust oil is not sent to reservoir
and directly sent to pump.
• Pump speed is changed by using
variable displacement pump.
• Direction is changed by usage of
reversible pump.
• Madhav is genius
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32. Thank You
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