Hydraulic and Pneumatic Actuators
and their Application Areas
Elena Ponomareva
JASS 2006 – St. Petersburg
1
06.04.2006
Introduction
Figure A. Automatic Pneumatic Drive:
UGM - units of gas networks and mains; PA - pneumatic amplifiers;
PE - pneumatic engines; MT - the mechanism of transfer; CSD converting and summing device; ACE - amplifiers of capacity of
electric signals; EMC - electromechanical converters; DF - devices of
feedbacks; AC - adjusting circuits; IF - internal feedbacks; GG - a
source of gas energy
2
Pneumatic Actuators
3
Gas Laws
The combined gas law
Boltzmann’s equation
p1V1 p2V2

T1
T2
1
3
2
m  c  kT
2
2
The ideal gas law
pV  nRT





4
P is the pressure in atmospheres
(atm) or kilopascals (kPa);
V is the volume in liters
n is the number of moles of gas
R is the ideal gas constant in
L atm/mol K or Pa m³/mol K
T is the temperature in kelvins.





3
1
kT
m  c2 
The strings 2
and 2
are the Kinetic Energy
m refers to the mass of one atom
< c2 > refers to the average of c2
k refers to the Boltzmann
constant
T refers to the temperature of the
surroundings
Classification Of Pneumatic Actuators
All pneumatic actuators can be subdivided into the
following types:
diaphragm pneumatic actuators;
pneumatic power cylinders;
gas-engine pneumatic actuators;
turbine pneumatic actuators;
jet pneumatic actuators;
pneumomuscles;
combined pneumatic actuators.
5
Diaphragm Pneumatic Actuators
Figure 1.1. The membrane pneumatic actuator:
1 - the connecting pipe of the second cavity; 2 the connecting pipe of the first cavity; 3 - the
membrane; 4 - the case; 5 - the rod; G1 - the
second charge of a gas stream in the first
cavity; G2-the second charge of a gas stream
in the second cavity; p1 - pressure of gas in the
first cavity; р2 - pressure of gas in the second
cavity; xr - moving of the rod
6
Figure 1.2. The sylphon pneumatic actuator:
1 - the connecting pipe of the second cavity; 2 the connecting pipe of the first cavity; 3 - the
case; 4 — the rod with the piston of the first
cavity; 5 - a sylphon of the first cavity; 6 – the
closing up of the sylphon of the first cavity
Pneumatic Power Cylinders
7
As compressed air moves into the
cylinder, it pushes the piston along
the length of the cylinder.
Compressed air or the spring,
located at the rod end of the
cylinder, pushes the piston back.
Pneumatic Power Cylinders
A double acting pneumatic cylinder has twodirected powered motion, with pressure on
both sides.
8
Pneumatic Power Cylinders
9
Pneumatic Power Cylinders
10
Optimal range
•Good running performance and long service
life thanks to smooth, hard cylinder bore
•Piston rod and cylinder barrel made of
stainless steel
More than the standard
•Round cylinders with piston diameters from
8 to 25 mm conform to ISO 6432, DIN ISO
6432. Variants are based on these standards.
The series is not repairable.
•The cap is swaged onto the barrel.
Functional
Three different end caps mean numerous
functional and spacesaving designs
Variants
•Non-rotating
•Through piston rod
•With or without position sensing
•Cushioning non-adjustable at either end or cushioning adjustable at both ends
•Further piston rod variants
Pneumatic Power Cylinders
The piston rods are
connected with the
same piston.
Double-rod
cylinders provide
equal force and
speed in both
directions.
11
Double-acting
double-rod
cylinder – doubleacting cylinder
with a piston rod
extending form
each end.
Pneumatic Power Cylinders
12
•Fast or slow valve actuation
•Position sensing
•Internal air channels eliminate
protruding tubing and
attachments, and thus also
harmful accumulation of
contaminants
•Suitable for manual on-site use,
as well as automatic operation
•Opening and closing actuated
via flange-mounted solenoid
valve with port pattern to Namur,
or via valve terminals with a
choice of 30 different fieldbus
protocols
•Sturdy and reliable, even in
aggressive environments
•Highly corrosion resistant
Festo Copac Linear Actuator
Pneumatic Power Cylinders
13
•Ball-bearing
circulating guide
system for a long
service life when
operated vertically
•Double piston rod for
a high level of force
in spite of a flat
design
•Compact
dimensions
•Symmetric geometry
•Low weight
•Wide variety of
mounting options
Ideal for vertical use
The ZSC series is available in five sizes
with piston diameters of 6 to 25 mm and
strokes from 10 to 100 mm (in 10 mm
increments). The mini slides operate at a
speed between 0.05 to 0.5 m/s (0.16 to
1.6 ft/s) at an operating pressure of 1.5 to
7 bar (22 to 102 psi).
Pneumatic Power Cylinders
14
The GPC series is ideal for
all applications that demand
absolute precision and side
load capacity. Compared to
standard cylinders, cylinders
from this series offer
extremely
precise movement, high
side load capacities, and
also torsion protection.
This results in fewer outer
guides to design and set up
machines.
Pneumatic Power Cylinders
Tandem cylinders ADVUT
15
By connecting 2, 3 or 4 cylinders with the
same piston diameter and stroke in series,
the force in the advance stroke (thrust) can
be doubled, tripled or quadrupled in
comparison to a single cylinder.
• A maximum of 4 cylinders can be combined.
• The internal distribution of compressed air means
that only 2 connections are required to pressurise
all cylinders.
• The force in the return stroke corresponds to that
of a single cylinder with corresponding piston
diameter.
Pneumatic Power Cylinders
Shock influence is required in a number of technological operations, such as
punching, marking, punching of holes. In this case we use shot
pneumocylinders.
16
Figure 1.3. The scheme of the shot pneumocylinder:
A, b, c – cavities; 1, 3, 4 – channels; 2 - aperture
Pneumatic Power Cylinders
In technological operations
when the executive
mechanism is, for example,
the cutting tool or a gearshift,
it is necessary to establish
two and more fixed positions,
multiposition
pneumocylinders or
pneumatic positioners are
used.
17
Figure 1.4. Threeposition pneumocylinder:
A, B, C - control valves; 1, 2, 3 – channels; T1, T2 – pneumothrottles; a, b –
cavities; Рip - pressure of compressed air in cavities a and b
Pneumatic Power Cylinders
18
•Compact – fitting length relative to stroke
•Loads and devices can be directly mounted on the
slide
•All settings accessible from one side:
•Precision end-position
adjustment
•Position of proximity sensors
•Mounting of drive
•Speed regulation
•Pneumatic endpositioncushioning
•Sealing system
Pneumatic Power Cylinders
Figure 1.5. The hose
pneumocylinder:
1 – hose;
2 - rollers of the carriage;
3 - control valve;
B
19
Pneumatic Power Cylinders
• Nominal swivel angles of 90°, 180°, 270° or
360°
• Freely selectable swivel angle from 0 to 360°
• With adjustable end-position cushioning at both
ends and end-position adjustment for piston ∅ 16
to 100 mm
• With adjustable end-position cushioning at both
ends for piston ∅ 40 to 100 mm
20
Figure 1.6 Rotary
pneumoactuator:
1, 2, 5 - channel;
3piston; 4 - chain transfer;
A - cavity; Рip - pressure
• For contactless position
sensing
• Backlash-free power
transmission
• Wide choice of mounting
options
Pneumatic Power Cylinders
Figure 1.7 Chamber
rotary
pneumoactuator:
1 – channel;
2 - chamber;
3, 4 – levers;
5 - detail
21
Pneumatic Power Cylinders
The pneumomotor with the limited
angle of turn is applied to perform
oscillating movements of the output
shaft or its rotation on the definite
angle.
22
Figure 1.8 The pneumomotor with the
limited angle of turn:
1 - case; 2 - blade: 3 - target shaft; 4 compaction; 5, 6 - fittings; 7 - stops
Pneumatic Power Cylinders
Figure 1.9 Lateral force Fq as a
function of stroke length l .
23
Pneumatic Power Cylinders
Figure 1.10 Pneumomuscle:
1 - internal elastic tube; 2 - braid;
3, 4 – covers; 5 – feeding channel
Figure 1.12 Geometrical parameters of
reduced pneumomuscles:
1 - braid; 2 - internal elastic tube;
3 – pantograph’s cell
Figure 1.11 Comparative characteristics of
output efforts of the power cylinder and the
pneumomuscle:
24
1 - power cylinder; 2 - pneumomuscle
Pneumatic Power Cylinders
Figure 1.13 The artificial muscle:
1 – casing; 2 - elastic tube; 3 –
thermoelement; 4 – filler; 5 electric leading-out wires
25
Pneumatic Power Cylinders
Figure 1.14 The
electropneumatic actuator:
1 - amplifier of direct current;
2 - electromechanical converter;
3 - choker; 4 - nozzles, 5 throttles, 6, 7 - executive
pneumocylinders, 8, 9 feedback sensors 10 - spring,
11 - flywheel
26
Directional Control Valves
27
The Stream Regulator
28
Advantages and disadvantages
Advantages:
•simplicity of realization relatively
to small back and forth motions;
•sophisticated transfer
mechanisms are not required
•low cost
•high speed of moving
•ease at reversion movements
•tolerance to overloads, up to a
full stop.
•high reliability of work
•explosion and fire safety
•ecological purity
•ability to accumulation and
transportation
29
Disadvantages:
•compressibility of the air
•impossibility to receive uniform and
constant speed of the working bodies
movement
•difficulties in performance at slow
speed
•limited conditions – use of
compressed air is beneficial up to the
definite values of pressure (the cost
of compressed air productior
increases sharply when the pressure
in the system exceeds 8…10 bar)
•compressed air requires good
preparation (the air should be cleared
of mechanical impurity and should be
free of moisture)
Hydraulic Actuators
30
Bernoulli's Equation
The original form of Bernoulli's
equation
v2
p
 gh   const
2






31
v = fluid velocity along the
streamline
g = acceleration due to gravity
on Earth
h = height from an arbitrary
point in the direction of gravity
p = pressure along the
streamline
ρ = fluid density
The second, more general form
of Bernoulli's equation
v2
p
     const ,    
2




φ is the gravitational potential
energy per unit mass
ω is the fluid enthalpy per unit
mass
ε is the fluid thermodynamic
energy per unit mass
The Structure of Hydraulic Cylinders
Figure 2.1. The hydraulic cylinder:
a - one- sided action with a
returnable spring; b — doublesided action controlled by the
differential scheme; 1 — plunger;
2 — spring; 3 — basic sealant; 4
— antisplash sealant; 5 — piston;
6 — nternal sealant; 7 — rod; 8
— a basic external sealant; 9 —
antisplash external sealant; 10 —
rod’s cavity; 11 — supply circuit;
I, II — positions of a control
valve; F — external force; S —
the full area of the piston; S' - the
ring area of the piston; Q, q —
submission and plums of a
stream accordingly
32
The Structure of Hydraulic Cylinders
Figure 2.2. The hydraulic cylinder
with a double-sided rod:
a - with the fixed rod; b — with the
fixed hydraulic cylinder and a
control valve; 1—internal
consolidation; 2, 5 — antisplash
external consolidations; 3, 4 —
basic external consolidations; F external force; h — course of the
piston; p1, р1' — low pressure;
p2, р2' — high pressure; Q — the
charge; v — speed of the piston
33
The Structure of Hydraulic Cylinders
Figure 2.3. The threehigh-speed hydraulic
cylinder:
1,3, 6
— hydrolines; 2 — the
internal hydraulic
cylinder; 4, 5 —
cavities; F— external
force; S1 - area of the
hydraulic cylinder 2; S2,
S3- area of cavities 5
and 4 accordingly
34
The Structure of Hydraulic Cylinders
Figure 2.4. The telescopic hydraulic cylinder:
1,6-pistons; 2, 3 — cavities; 4 — sleeve; 5 — hydroline; 7 —
supply; F- the external force; S1. S2 —the area of cylinders with
pistons 1 and 6 accordingly; S3, S4- areas of cavities 2 and 3
accordingly
35
The Structure of Hydraulic Cylinders
Figure 2.5. The hydraulic cylinder with trailer throttle brakes
and the protected rod:
1 - throttle; 2,3 - sockets; 4 — rubber sylphon; 5 — return
valves; 6,7- ledges of the piston; 8 — ring volume; other
designations see on fig. 2.2
36
The Structure of Hydraulic Cylinders
Figure 2.6. The piston of
the hydraulic cylinder
with fixing devices:
1 - sealant element;
2 — conic surface;
3 — ball;
4 — spring;
5, 7 — cavities of the
hydraulic cylinder;
6 — piston
37
The Structure of Hydraulic Cylinders
Figure 2.7. Consolidation
of rods (a, b) and
pistons (c, d) of
hydrocylinders:
a – with a round rubber
ring; b,c – with V-look
cuffs; d — with a
bilateral cuff; 1 —
aprotective ring; 2 —
plastic persistent ring;
3 — rubber ring; 4 —
nut; 5— dividing plastic
cuff; 6 — consolidating
rubber cuff; 7 —
directing belt of a cuff;
8— cuff; 9 — bilateral
cuff
38
Volumetric Hydraulic Actuator
Figure 2.8. Hydraulic Jack
In this system , a
reservoir and a system
of valves has been
added to a simple
hydraulic lever to
stroke a small cylinder
or pump continuously
and raise a large piston
or an actuator a notch
with each stroke.
39
Volumetric Hydraulic Actuator
Figure 2.9. Basic schemes of a hydraulic actuator:
a - forward movement; b — rotary movement; c — hydromotor;
1 — hydraulic engine; 2 — hydraulic control valve; 3 —
hydrotank; 4 — adjustable pump; 5 — safety valve; F —
working force
40
Volumetric Hydraulic Actuator
Figure 2.10. The scheme of a hydraulic actuator with the
closed circulation of a liquid:
1 - adjustable pump; 2— auxiliary pump; 3 — downflow flap; 4
— return flap; 5— safety flaps; 6 — hydraulic engine
(adjustable hydromotor); a, b — hydrolines
41
Volumetric Hydraulic Actuator
Figure 2.11. The scheme of
a hydraulic actuator with
a regulator of a stream:
1— regulator; 2 —
adjustable throttle; 3 —
reducing valve; Рth pressure in a throttle upon
an input; Рp - pressure of
the pump
42
Volumetric Hydraulic Actuator
Figure 2.12. The scheme of a
hydraulic actuator with
steady output rotation
frequency:
1 - a pump; 2 — a hydromotor;
3 — the shaft of the
hydromotor; 4 — a centrifugal
regulator; 5 — the valve of the
hydraulic control valve ; 6 —
the hydrocylinder; 7 — a disk
43
Volumetric Hydraulic Actuator
Figure 2.13 The scheme
of a stream divider:
1 — throttles; 2, 3 —
apertures; 4 — a piston; 5
— a sleeve; M — a point of
division of stream Q on
streams Q1, and Q2
44
Follower Hydraulic Actuator
Figure 2.14 The scheme of a follower hydraulic
actuator of cross-section submission of a
support of the copy machine tool:
1 - piston; 2 — cavity; 3 — hydraulic control valve; 4
— bringing hydroline; 5 —probe; 6 — master cam; 7
— the case of the hydraulic cylinder; 8 — the case
of the support; 9 — support
Figure 2.15 The scheme of the hydraulic
booster with a mechanical feedback::
1 - point (hinge); 2—draft; 3 — piston; 4 —
power cylinder; 5 — hydraulic control valve; 6 —
rod (an output link); 7 — a point of an output link;
8 — differential lever; n, m – links of a doubleshouldered lever
45
Piston-type Hydraulic Actuator
46
Bag-Type Accumulator
47
Advantages and Disadvantages
48
Variable hydraulic actuators are widely used as
drives of machine tools, rolling mills, pressing and
the foundry equipment, road and building machines,
transport and agricultural machines, etc. A number of
advantages in comparison with mechanical and
electric transfers explains such their wide application:
•infinitely variable control of gear-ratio in a wide
range and an opportunity to create the big reduction
ratio;
•small specific weight, i.e. the weight of a
hydroactuator is in ratio to transmitted capacity
(0,2...0,3 kg / kWt);
•opportunity of simple and reliable protection of the
engine from overloads;
•small sluggishness of the rotating parts, providing
fast change of operating modes (start-up, dispersal,
a reverser, a stop);
•simplicity of transformation of rotary movement into
reciprocating one;
•opportunity of positioning a hydraulic engine on
removal(distance) from an energy source and
freedom in making configuration.
It is also necessary to reckon with
disadvantages of hydraulic
actuators:
•Efficiency of a volumetric hydraulic
actuator is a little bit lower, than
efficiency of mechanical and electric
transfers, and during regulation it is
reduced;
•conditions of operation of a
hydraulic actuator (temperature)
influence its characteristics;
•Efficiency of a hydraulic actuator is
a little reduced in the process of
exhaustion of its resource owing to
the increase in backlashes and the
increase of outflow of liquid (falling
of volumetric efficiency);
•sensitivity to pollution of working
liquid and necessity of high culture
service.
Some More Cylinders
Multi-position cylinder
49
Some More Cylinders
Linear/swivel clamp CLR
50
Some More Cylinders
Swivel/linear units DSL
51
Some More Cylinders
Bellows cylinders
52
Some More Cylinders
Fluidic Muscle
53
Some More Cylinders
54
Some More Cylinders
Festo servopneumatic systems
55
Control Systems
56
Figure 4.1.
Control Systems
Let's consider a control system of a pneumatic or hydraulic drive with
the use of PLC controller. The block diagram of system is specified in
the following diagram.
Logical scheme
– electrical,
pneumatic,
hydraulic.
Logical scheme
Executive devices
Sensors, controllers and operating control
Sensors – contacts, inductive, capacitive,
optical, hydraulic, pneumatic, PLC.
57
Executive devices –
hydro- and
pneumocylinders, hydroand pneumomotors and
so on.
Control Systems
Figure 4.2
58
Figure 4.3.
Control Systems
Example
Ìàíèïóëÿòîð.swf
59
Control Systems
Датчики
I0.0
a0
A+
O0.0
O0.1
I0.1
a1
A-
Gripping device
СХВАТ
Датчики
I0.2
b0
B+
O0.2
O0.3
ЦИЛИНДР
60
I0.3
b1
B-
Cylinder
Control Systems
ЦИКЛОГРАММА РАБОТЫ СХВАТА
a1
A-
A+
Gripping device
a0
ЦИКЛОГРАММА РАБОТЫ ЦИЛИНДРА
b1
B-
B+
b0
61
Шаг1
Step
1
Шаг2
Step
2
Шаг33
Step
Шаг4
Step
4
Cylinder
Control Systems
Sensors
A  a 0  a1 b0  b1
Steps
1
2
3
4
a0
1
0
0
0
a1
0
1
1
0
A  a 0  a1 b0  b1
b0
1
1
0
0
B   a 0  a1 b0  b1
b1
0
0
1
1
Commands
62
B   a 0  a1 b0  b1
A  a0  b0
B   a1 b0
A  b0
B   a1
0
A  a1 b1
A  b1
1
B   a0  b1
B   a0
A+
1
0
0
0
A-
0
0
1
0
B+
0
1
0
B-
0
0
0
Control Systems
FST 4.10
63
Control Systems
Sensors
Inductive
64
Contact
Capacitor
Application Areas
The right product for the right demands …
65
Application Areas
Pneumatic processing centers
66
Figure. 5.1. The scheme of
the pneumatic machining
center
Figure 5.2. The scheme of the pneumatic
processing center for material’s sawing:
1 -work material; 2 -a power cylinder for a
longitudinal motion; 3 - a power cylinder for
a vertical motion; 4 – saw; 5 – supports; 6 –
rotary actuator
Application Areas
Table: Scopes of systems with pneumatic muscles
67
Characteristics
Platform
positioning
Good dynamics
Large working efforts
Accuracy of positioning
Simplicity of a design
Brake
actuator
Good controllability
Absence of friction of rest
Simplicity of a design and
operation
Tightening
devices
The big efforts of a clip
Compactness
Small weight
Underwater
Corrosion preventing
Tightness
Small consumption of
working gas
Sorting
levers
Big working efforts and
acceleration
Simplicity of a design
Amortization of working
loadings
Walking
Elevating
devices
Big working efforts and
acceleration
Amortization of working
loadings
Simplicity of a design
Counterbal
ancing
Scheme
Application
Characteristics
Application
devices
platforms
devices
Good dynamics
Simplicity of a design
Small weight
Ease of positioning
Adjustment of elasticity
Adaptibility of
characteristics
Smoothness of job
Small weight
Scheme
Application Areas
Batching
Figure 5.3. The scheme of batching:
1 – tank; 2 – fluid; 3 – a lever with a ladle; 4 - power
cylinder; 5 – accepting chamber
68
Application Areas
Robotics
Figure 5.4.
69
Application Areas
Robotics
70
Figure 5.6
Figure 5.5. The scheme of the mobile robot:
1,2 – longitudinal pneumatic cylinders; 3,4 – transversal pneumatic cylinders; 5 – lifting cylinder; 6
– pedipulator; 7 – metaldetector; 8 – infra-red sensor; 9 – the chemical sensor; 10 – sensor of
longitudinal position movement; 11 - sensor of cross-section position movement; 12 - block of
valves; 13 – block of rotation; 14 – electronic compass; 15 – onboard compass
Application Areas
Figure 5.7. The scheme of the
mobile robot with vertical
displacement:
1 - longitudinal movement module;
2 - rotating movement module; 3 –
console; 4,5 - vacuum gripping
devices; 6,7 - elevating cylinders; 8
–trajectory of turn
71
Questions?
72