Upload
amr-elghobashi
View
217
Download
0
Embed Size (px)
Citation preview
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
1/19
ALEXANDRIA UNIVERSITY
FACULTY OF ENGINEERING
Mechanical Engineering Department
Hydraulic Machines and Fluid Mechanics Branvh.
------------------------------------------------------------------------------------------------------------------------------------- ----------------------
9thTerm Electromechanical Program
FALL Term (Sept Dec 2012)
Fluid Power Systems
By
Dr. Ihab Gaber Ahmed Adam
Mechanical Engineering Department
Faculty of Engineering
Alexandria University
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
2/19
ALEXANDRIA UNIVERSITY
FACULTY OF ENGINEERING
Mechanical Engineering Department
Hydraulic Machines and Fluid Mechanics Branvh.
------------------------------------------------------------------------------------------------------------------------------------- ----------------------
__________________________________________________________________________________________________
Dr.Ihab G. Adam FALL 2012 9thTerm Elctomechanical Program.
Introduction-1
Hydraulic Power SystemsOutline:
1.
Introduction
2. Basic hydraulic system components and its hydraulic symbols
-
Pumps
- Actuators (Hydraulic cylinders and motors)
- Control Valves (Direction - Flow - Pressure)
3. Analysis (construction and operation) of some basic hydraulic circuits
4. Applications on Hydraulic Equipments circuits ( Loader,)
References:
1. Anthony Esposito, "Fluid Power with Applications."
2. F. N. Norvelle, "Fluid Power Technology."
3. Michael J. Pinches and John G. Ashby, "Power Hydraulics."
Fluid Systems
Fluid Transport Systems Fluid Power Systems
Fluid Poweris the technology that deals with generation, control and transmission of power using
pressurized fluids.
Fluid Power Systems
Fluid power system is a mechanism for converting mechanical power into hydraulic power (kinetic
and pressure) in a fluid, transmitting that power through a conduit, control it and then reconverting it
to mechanical power in order to perform work.
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
3/19
ALEXANDRIA UNIVERSITY
FACULTY OF ENGINEERING
Mechanical Engineering Department
Hydraulic Machines and Fluid Mechanics Branvh.
------------------------------------------------------------------------------------------------------------------------------------- ----------------------
__________________________________________________________________________________________________
Dr.Ihab G. Adam FALL 2012 9thTerm Elctomechanical Program.
Introduction-2
Fluid Power Systems
Hydraulic Power Systems Pneumatic Power Systems
use incompressible fluid (Liquids) use compressible fluid (gases)
- Water (freezes, evaporates, is poor Air
lubricant and rust metal components)
- Oil
Advantages of Fluid Power Systems:
1. High torques or forces from compact (small) size unit.
2. Stepless (infinitely) variable speeds and forces (or torques).
3. High accuracy of control.
4. Instantly reversible, eliminating the need to come to a gradual stop.
5. Self lubrication
6.
Fully adapted to electrical and electronic control.
7. Provide cushioning to reduce the mechanical effects of impact or shock loads.
Disadvantages of Fluid Power Systems:
1.
High pressure hazards.
2. Fire hazards.
3. Possible leakage of the fluid.
4. Component's wear due to contamination of the fluid.
Applications of Fluid Power SystemHydraulic systems are extremely important to the operation of heavy equipment. Basic hydraulic
principles are used when designing hydraulic implement systems, steering systems, brake systems
and power train systems. An understanding of the basic hydraulic principles must be accomplished
before continuing into machine systems.
1. Fluid power steers and breaks.
2. Machine tool industry.
3.
Food processing.
4. Drills teeth.
5.
Control airplanes (flaps, landing gear, and doors).
6. Cranes.
7. Lift truck.
8. Agricultural equipments.
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
4/19
ALEXANDRIA UNIVERSITY
FACULTY OF ENGINEERING
Mechanical Engineering Department
Hydraulic Machines and Fluid Mechanics Branvh.
------------------------------------------------------------------------------------------------------------------------------------- ----------------------
__________________________________________________________________________________________________
Dr.Ihab G. Adam FALL 2012 9thTerm Elctomechanical Program.
Introduction-3
Hydraulic Power System Components
1. Fluids (usually oil)
-To transmit power.
-To lubricate moving parts.
-To dissipate heat.
-To seals clearances between mating parts.
2. Tanks
-
To hold the fluid.-To allow fluid cooling.
-To allow foam (air bubble) separation.
3. Fluid Conditioning Device
-To keep the fluid clean (Filters)
-To Cool the fluid
4. Positive Displacement Pumps
-
The source of the hydraulic power-Convert the mechanical power to hydraulic power.
5. Prime mover
-Electrical motor, diesel engine and gasoline engine
-To drive the pump
6. Actuators
-Hydraulic cylinder for linear motion
-
Hydraulic motor for rotary motion
-
To perform work
7. Control Valves
-To control fluid flow rate (Flow Control Valve)
-To control fluid flow direction (Direction Control Valve)
-To control fluid flow pressure (Pressure Control Valve)
8. Conductors
-
Pipes or tubes - To carry the fluid
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
5/19
ALEXANDRIA UNIVERSITY
FACULTY OF ENGINEERING
Mechanical Engineering Department
Hydraulic Machines and Fluid Mechanics Branvh.
------------------------------------------------------------------------------------------------------------------------------------- ----------------------
__________________________________________________________________________________________________
Dr.Ihab G. Adam FALL 2012 9thTerm Elctomechanical Program.
Introduction-4
Mobile construction machines are designed using various hydraulic components (tanks,
fluids, pumps and motors, valves and cylinders). Some components when used in different parts of
the circuit perform different functions. Although these components may look alike, they may be
given different names. The ability to identify the component, state the components function and
describe the components operation will allow the serviceman to reduce complex circuits to several
simple circuits that may be more easily understood.
Hydraulic Jack
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
6/19
ALEXANDRIA UNIVERSITY
FACULTY OF ENGINEERING
Mechanical Engineering Department
Hydraulic Machines and Fluid Mechanics Branvh.
------------------------------------------------------------------------------------------------------------------------------------- ----------------------
__________________________________________________________________________________________________
Dr.Ihab G. Adam FALL 2012 9thTerm Elctomechanical Program.
Introduction-5
Pumps
Mechanical Power (T) Pump Hydraulic Power (PQ)
Non-Positive Displacement Pumps Positive Displacement Pumps
Hydrodynamic Pumps Hydrostatic Pumps
-
High flow rate (Q)
- Low Pressure (P)
-
Used in fluid transport
- Centrifugal Pump
- Propeller (axial) pump
- Smooth and continuos flow
- Qis inversely proportion to P
- No need for pressure relief valve
-
Low flow rate (Q)
- High Pressure (P)
-
Used in fluid power
- Gear Pump
- Vane Pump
- Piston Pump
- Relatively pulsating flow
- Qis almost constant60
NVQ
DT
- Pressure relief valve must be used to
protect the pump against over
pressure.
Pump's Hydraulic Symbols
Unidirectional Fixed displacement pump
Unidirectional Variable displacement pump
Bi-directional Fixed displacement pump
Bi-directional Variable displacement pump
Pumps do not pump pressure, but they produce fluid flowPressure is due to the elevation difference, friction resistance and/orLOADS
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
7/19
ALEXANDRIA UNIVERSITY
FACULTY OF ENGINEERING
Mechanical Engineering Department
Hydraulic Machines and Fluid Mechanics Branvh.
------------------------------------------------------------------------------------------------------------------------------------- ----------------------
__________________________________________________________________________________________________
Dr.Ihab G. Adam FALL 2012 9thTerm Elctomechanical Program.
Introduction-6
Si ng le su ct io n Do ub le s uc ti on
Multi stages
Centri fugal ( impel ler ) type Axial (propeller ) type
Non Positive disp lacement
External Internal
screw lobe
Gerotor
Gear pu mps
Unbalanced Balanced
vane pumps
Bent axis Sw ash plate
Axial Radial
piston pumps
Positive di splacement
Hydraulic Pumps
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
8/19
ALEXANDRIA UNIVERSITY
FACULTY OF ENGINEERING
Mechanical Engineering Department
Hydraulic Machines and Fluid Mechanics Branvh.
------------------------------------------------------------------------------------------------------------------------------------- ----------------------
__________________________________________________________________________________________________
Dr.Ihab G. Adam FALL 2012 9thTerm Elctomechanical Program.
Introduction-7
Positive Displacement Pumps
With this pump, a definite volume of liquid is delivered for each cycle of pump operation,
regardless of resistance, as long as the capacity of the power unit driving a pump is not exceeded. If
an outlet is completely closed, either the unit driving a pump will stall or something will break.
Therefore, a positive-displacement-type pump requires a pressure regulator or pressure-relief valve
in the system.
60
NVQ dTh
Th
Actual
Q
QVol
meVolTotal *
Positive Displacement Pump Performance curves
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
9/19
---- ----------------
_______
Dr.Ih
ALE
FAC
Mech
Hydraul
----------------
__________
b G. Ada
ANDRIA
LTY OF
nical Engi
ic Machines a
----------------
__________
UNIVERS
NGINEE
eering Dep
d Fluid Mecha
----------------
__________
ITY
ING
artment
nics Branvh.
---------------
__________
ALL 2012
I. Ge
----------------
__________
r Pu
----------------
__________
9thTer
p
----------------
__________
Elctomech
I
----------------
__________
anical Progr
troduction
------
____
am.
-8
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
10/19
---- ----------------
_______
Dr.Ih
ALE
FAC
Mech
Hydraul
----------------
__________
b G. Ada
ANDRIA
LTY OF
nical Engi
ic Machines a
----------------
__________
UNIVERS
NGINEE
eering Dep
d Fluid Mecha
----------------
__________
II
III
Vd
ITY
ING
artment
nics Branvh.
---------------
__________
ALL 2012
. Vane
Pisto
n
----------------
__________
Pum
Pum
D2
----------------
__________
9thTer
p
----------------
__________
Elctomech
I
----------------
__________
anical Progr
troduction
------
____
am.
-9
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
11/19
ALEXANDRIA UNIVERSITY
FACULTY OF ENGINEERING
Mechanical Engineering Department
Hydraulic Machines and Fluid Mechanics Branvh.
------------------------------------------------------------------------------------------------------------------------------------- ----------------------
__________________________________________________________________________________________________
Dr.Ihab G. Adam FALL 2012 9thTerm Elctomechanical Program.
Introduction-10
Hydraulic Actuators
Hydraulic Power Actuators Mechanical Power
Hydraulic Cylinders Hydraulic Motors
for Linear Motion for Rotary Motion
Linear Hydraulic Actuators (Hydraulic Cylinders)
Single Acting Hydraulic Cylinder
Single acting cylinder can exert a force in only one direction (extension or retraction). Single actingcylinders do not retract hydraulically; it retracts by gravity or spring.
Double Acting Hydraulic Cylinder
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
12/19
---- ----------------
_______
Dr.Ih
ALE
FAC
Mech
Hydraul
----------------
__________
b G. Ada
Uni
Unidi
Bi-
Bi-di
ANDRIA
LTY OF
nical Engi
ic Machines a
----------------
__________
S
D
irectiona
ectional
irectiona
ectional
UNIVERS
NGINEE
eering Dep
d Fluid Mecha
----------------
__________
ingle-End
ouble-En
Hydr
l fixed dis
ariable d
fixed dis
ariable d
ITY
ING
artment
nics Branvh.
---------------
__________
ALL 2012
ed, Doub
ed, Doub
ulic mot
placemen
isplacem
placemen
splaceme
----------------
__________
e Acting
le Acting
r's Sym
t hydrauli
nt hydra
t hydrauli
nt hydrau
----------------
__________
9thTer
Cylinder
Cylinder
ols
c motor
lic motor
c motor
lic motor
----------------
__________
Elctomech
I
----------------
__________
anical Progr
troduction
------
____
am.
-11
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
13/19
---- ----------------
_______
Dr.Ih
1. Di
2. Pr
3. Fl
A chec
only o
Free Fl
The c1. Fa
2. Pre
3. By
4. Saf
It is us
ALE
FAC
Mech
Hydraul
----------------
__________
b G. Ada
ectional
ssure Co
w Contro
valveis a
e direction
w Direction
eck valvilitate mai
vent back
ass other
ety bypass
d to provid
ANDRIA
LTY OF
nical Engi
ic Machines a
----------------
__________
ontrol V
trol Valv
l Valves (
Di
simple on
and preven
e applicatenance
p pressur
omponen
to provide
e a positiv
UNIVERS
NGINEE
eering Dep
d Fluid Mecha
----------------
__________
lves (DC
es (PCV)
FCV)
rection
-way valv
ts flow in t
No Flow D
tions:
s(usually
an alternati
Pilot-lock for h
ITY
ING
artment
nics Branvh.
---------------
__________
ALL 2012
ontrol
V)
l ContrCheck(Non-ret
e other dir
irection
ressure or
e flow pat
peratedlding susp
----------------
__________
alves
l Valvealve
rn valve)
ection.
flow contro
h around a
Check Vnded load
----------------
__________
9thTer
s (DCV
hat allows
l valves)
filter or he
alvein place.
----------------
__________
Elctomech
I
fluid to flo
t exchange
----------------
__________
anical Progr
troduction
through i
------
____
am.
-12
in
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
14/19
ALEXANDRIA UNIVERSITY
FACULTY OF ENGINEERING
Mechanical Engineering Department
Hydraulic Machines and Fluid Mechanics Branvh.
------------------------------------------------------------------------------------------------------------------------------------- ----------------------
__________________________________________________________________________________________________
Dr.Ihab G. Adam FALL 2012 9thTerm Elctomechanical Program.
Introduction-13
Directional Control Valves
Two-Position Directional Control Valves
Four Way Valve
Manual-actuated, two-position, four-way, four
ports, spring-offset Directional Control Valve.
Mechanical-actuated, two-position, four-way, fourports, spring-offset Directional Control Valve.
Solenoid-actuated, two-position, four-way, four
ports, spring-offset Directional Control Valve.
Three-Position Directional Control Valves
Manual-actuated, three-position, four-way, four
ports, spring-centered Directional Control Valve.
Pilot-actuated, three-position, four-way, four
ports, spring-centered Directional Control Valve.
Solenoid-actuated, three-position, four-way, four
ports, spring-centered Directional Control Valve.
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
15/19
---- ----------------
_______
Dr.Ih
ALE
FAC
Mech
Hydraul
----------------
__________
b G. Ada
Vari
ANDRIA
LTY OF
nical Engi
ic Machines a
----------------
__________
ous cente
UNIVERS
NGINEE
eering Dep
d Fluid Mecha
----------------
__________
r flow pa
ITY
ING
artment
nics Branvh.
---------------
__________
ALL 2012
ths for t
----------------
__________
ree-posit
----------------
__________
9thTer
ion, four
----------------
__________
Elctomech
I
way val
----------------
__________
anical Progr
troduction
es
------
____
am.
-14
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
16/19
ALEXANDRIA UNIVERSITY
FACULTY OF ENGINEERING
Mechanical Engineering Department
Hydraulic Machines and Fluid Mechanics Branvh.
------------------------------------------------------------------------------------------------------------------------------------- ----------------------
__________________________________________________________________________________________________
Dr.Ihab G. Adam FALL 2012 9thTerm Elctomechanical Program.
Introduction-15
Pressure Control Valves (PCV)
Pressure Relief Valve
It is used as a safety device to prevent over pressurizing the system.
Pressure Reducing Valve
Pressure reducing valves are used when we need to operate one or more branches of afluid power circuit at pressures lower than the maximum system pressure.
Comparison of Pressure Relief Valve and Pressure Reducing Valve
Pressure Relief Valve Pressure Reducing Valve
1. Senses pressure upstream of
the valve.
2. Outlet port returns to tank.
3. Outlet flow at tank pressure
(usually near atmospheric).
4. Valve normally closed.
1. Senses pressure downstream of the
valve.
2. Outlet port attached to branch circuit.
3. Outlet flow at branch circuit pressure.
4. Valve normally open.
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
17/19
---- ----------------
_______
Dr.Ih
Unloa
The pa syst
ALE
FAC
Mech
Hydraul
----------------
__________
b G. Ada
ding valv
rpose ofm.
ANDRIA
LTY OF
nical Engi
ic Machines a
----------------
__________
s unload
sequenc
UNIVERS
NGINEE
eering Dep
d Fluid Mecha
----------------
__________
the pump
e valve is
ITY
ING
artment
nics Branvh.
---------------
__________
ALL 2012
nloadin
flow to t
Sequenc
to contro
----------------
__________
Valve
e tank at
Valve
l the orde
----------------
__________
9thTer
nearly ze
of opera
----------------
__________
Elctomech
I
o pressur
ion of tw
----------------
__________
anical Progr
troduction
e.
o branche
------
____
am.
-16
s of
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
18/19
---- ----------------
_______
Dr.Ih
The o
rate a
acco
1. Va
2. Va
3. Us
Flow
ALE
FAC
Mech
Hydraul
----------------
__________
b G. Ada
ly way t
t which
plished b
ying the
ying the
ng a flo
control
ANDRIA
LTY OF
nical Engi
ic Machines a
----------------
__________
control
the fluid
peed of
utput of
control
alve wit
dire
UNIVERS
NGINEE
eering Dep
d Fluid Mecha
----------------
__________
Fl
he speed
flows i
fixed dis
a variable
alve
Adjust
an inter
tion and
ITY
ING
artment
nics Branvh.
---------------
__________
ALL 2012
w Contr
of the ac
to or o
placemen
displace
able flow
al check
free flow
----------------
__________
ol Valves
uator (cy
t of the
t pump.
ent pum
control
valveto
in the oth
----------------
__________
9thTer
inder or
actuator.
alve
allows fo
er directi
----------------
__________
Elctomech
I
otor) is
This co
restricte
n
----------------
__________
anical Progr
troduction
o control
ntrol can
flow in
------
____
am.
-17
the
be
ne
7/24/2019 Fluid Power Systems for Electromech Prog 9th Term-Introduction
19/19
ALEXANDRIA UNIVERSITY
FACULTY OF ENGINEERING
Mechanical Engineering Department
Hydraulic Machines and Fluid Mechanics Branvh.
------------------------------------------------------------------------------------------------------------------------------------- ----------------------
__________________________________________________________________________________________________
D Ih b G Ad FALL 2012 9th T El h i l P
Introduction-18
Basic Hydraulic Circuits
Control of a single-acting cylinder Control of a double-acting cylinder
Regnerative circuit Drilling machine application
Double-pump hydraulic system Locked cylinder using pilot check valve