06.04.2006 1 Hydraulic and Pneumatic Actuators and their Application Areas Elena Ponomareva JASS 2006 – St. Petersburg.

06.04.20061

Hydraulic and Pneumatic Actuators and their Application Areas

Elena Ponomareva

JASS 2006 – St. Petersburg

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IntroductionIntroduction

Figure A. Automatic Pneumatic DriveFigure 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

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Pneumatic ActuatorsPneumatic Actuators

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Gas LawsGas Laws

The combined gas lawThe combined gas law

The ideal gas lawThe ideal gas law

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.

2

22

1

11

T

Vp

T

Vp

Boltzmann’s equationBoltzmann’s equation

The strings and 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

nRTpV

kTcm2

3

2

1 2

2

2

1cm kT

2

3

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Classification Of Pneumatic Classification Of Pneumatic ActuatorsActuators

All pneumatic actuators can be subdivided into the All pneumatic actuators can be subdivided into the following types:following types:

diaphragm pneumatic actuators; pneumatic power cylinders;

gas-engine pneumatic actuators; turbine pneumatic actuators; jet pneumatic actuators;

pneumomuscles; combined pneumatic actuators.

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Diaphragm Pneumatic ActuatorsDiaphragm Pneumatic Actuators

Figure 1.1. The membrane pneumatic actuator: 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

Figure 1.2. The sylphon pneumatic actuator: 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

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Pneumatic Power CylindersPneumatic Power Cylinders

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.

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A double acting pneumatic cylinder has two- directed powered motion, with pressure on both sides.

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Optimal rangeOptimal range•Good running performance and long service life thanks to smooth, hard cylinder bore•Piston rod and cylinder barrel made of stainless steelMore than the standardMore 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.FunctionalFunctionalThree different end caps mean numerous Three different end caps mean numerous functional and spacesaving designsfunctional and spacesaving designsVariantsVariants•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

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The piston rods are connected with the same piston. Double-rod cylinders provide equal force and speed in both directions.

Double-acting double-rod cylinder – double-acting cylinder with a piston rod extending form each end.

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Festo Festo Copac Linear ActuatorCopac Linear Actuator

•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

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Ideal for vertical useIdeal 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).

•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

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The GPC seriesThe GPC series is ideal for all applications that demand absolute precision and sideload capacity. Compared to standard cylinders, cylinders from this series offer extremelyprecise movement, high side load capacities, and also torsion protection.This results in fewer outer guides to design and set up machines.

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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.

Tandem cylinders ADVUTTandem cylinders ADVUT

• 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.

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Figure 1.3. The scheme of the shot pneumocylinder:Figure 1.3. The scheme of the shot pneumocylinder:A, b, c – cavities; 1, 3, 4 – channels; 2 - aperture

Shock influence is required in a number of technological operations, such as punching, marking, punching of holes. In this case we use shot shot

pneumocylinderspneumocylinders.

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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.

FigureFigure 1. 1.44. . Threeposition pneumocylinder: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

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•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 end-positioncushioning

•Sealing system

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Figure 1.5. The hose Figure 1.5. The hose pneumocylinder:pneumocylinder:

1 – hose;

2 - rollers of the carriage;

3 - control valve;

B

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Figure 1.6 Rotary Figure 1.6 Rotary pneumoactuator:pneumoactuator:1, 2, 5 - channel; 3 - piston; 4 - chain transfer; A - cavity; Рip - pressure

• 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∅

• For contactless position sensing• Backlash-free power transmission• Wide choice of mounting options

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Figure 1.7 Chamber Figure 1.7 Chamber rotary rotary pneumoactuator:pneumoactuator: 1 – channel; 2 - chamber; 3, 4 – levers; 5 - detail

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Figure 1.8 The pneumomotor with the Figure 1.8 The pneumomotor with the limited angle of turn:limited angle of turn:

1 - case; 2 - blade: 3 - target shaft; 4 - compaction; 5, 6 - fittings; 7 - stops

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.

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Figure 1.9 Lateral force Figure 1.9 Lateral force FqFq as a as a function of stroke length function of stroke length ll ..

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Figure 1.10 Pneumomuscle:Figure 1.10 Pneumomuscle:1 - internal elastic tube; 2 - braid; 3, 4 – covers; 5 – feeding channel

Figure 1.11 Comparative characteristics of Figure 1.11 Comparative characteristics of output efforts of the power cylinder and the output efforts of the power cylinder and the pneumomuscle: pneumomuscle:

1 - power cylinder; 2 - pneumomuscle

Figure 1.12 Geometrical parametersFigure 1.12 Geometrical parameters of of reduced pneumomuscles: reduced pneumomuscles: 1 - braid; 2 - internal elastic tube;3 – pantograph’s cell

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Figure 1.13 The artificial muscle:Figure 1.13 The artificial muscle:

1 – casing; 2 - elastic tube; 3 – thermoelement; 4 – filler; 5 - electric leading-out wires

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Figure 1.14 The Figure 1.14 The electropneumatic actuator: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

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Directional Control ValvesDirectional Control Valves

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The Stream RegulatorThe Stream Regulator

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Advantages and disadvantages

Advantages: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

Disadvantages: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)

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Hydraulic Actuators

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Bernoulli's EquationBernoulli's Equation

The original formThe original form of Bernoulli's of Bernoulli's equationequation

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 The second, more general form of Bernoulli's equationof Bernoulli's equation

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

constp

ghv

2

2

p

constv

,2

2

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The Structure of Hydraulic CylindersThe Structure of Hydraulic Cylinders

Figure 2.1. The hydraulic cylinderFigure 2.1. The hydraulic cylinder: a - one- sided action with a returnable spring; b — double-sided 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

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Figure 2.2. The hydraulic cylinder Figure 2.2. The hydraulic cylinder with a double-sided rod: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

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Figure 2.3. The three-Figure 2.3. The three-high-speed hydraulic high-speed hydraulic cylindercylinder: 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

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Figure 2.4. The telescopic hydraulic cylinder: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

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Figure 2.5. The hydraulic cylinder with trailer throttle brakes Figure 2.5. The hydraulic cylinder with trailer throttle brakes and the protected rod: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

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Figure 2.6. The piston of Figure 2.6. The piston of the hydraulic cylinder the hydraulic cylinder with fixing devices:with fixing devices:

1 - sealant element; 2 — conic surface; 3 — ball; 4 — spring; 5, 7 — cavities of the

hydraulic cylinder; 6 — piston

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Figure 2.7. ConsolidationFigure 2.7. Consolidation of rods (a, b) and of rods (a, b) and pistons (c, d) of pistons (c, d) of hydrocylinders: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

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Volumetric Hydraulic ActuatorVolumetric Hydraulic Actuator

Figure 2.8. Hydraulic JackFigure 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.

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Figure 2.9. Basic schemes of a 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

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Figure 2.10. The scheme of a hydraulic actuator with the Figure 2.10. The scheme of a hydraulic actuator with the closed circulation of a liquid: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

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Figure 2.11. The scheme of Figure 2.11. The scheme of a hydraulic actuator with a hydraulic actuator with a regulator of a stream: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

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Figure 2.12. The scheme of a Figure 2.12. The scheme of a hydraulic actuator with hydraulic actuator with steady output rotation steady output rotation frequency: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

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Figure 2.13 The scheme Figure 2.13 The scheme of a stream divider: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

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Follower Hydraulic ActuatorFollower Hydraulic Actuator

Figure 2.15 The scheme of the hydraulic Figure 2.15 The scheme of the hydraulic booster with a mechanical feedback::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 double-shouldered lever

Figure 2.14 The scheme of a follower hydraulic Figure 2.14 The scheme of a follower hydraulic actuator of cross-section submission of a actuator of cross-section submission of a support of the copy machine tool: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

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Piston-type Hydraulic Actuator

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Bag-Type Accumulator

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Advantages and Disadvantages

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 advantagesadvantages 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 disadvantagesdisadvantages 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.

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Some More CylindersSome More Cylinders

Multi-position cylinderMulti-position cylinder

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Linear/swivel clamp CLRLinear/swivel clamp CLR

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Swivel/linear units DSLSwivel/linear units DSL

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Bellows cylindersBellows cylinders

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Fluidic MuscleFluidic Muscle

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Festo servopneumatic systemsFesto servopneumatic systems

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Control SystemsControl Systems

Figure 4.1.

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Logical scheme Executive devices

Sensors, controllers and operating control

Sensors – contacts, inductive, capacitive, optical, hydraulic, pneumatic, PLC.

Logical scheme – electrical, pneumatic, hydraulic.

Executive devices – hydro- and pneumocylinders, hydro- and pneumomotors and so on.

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.

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Figure 4.2 Figure 4.3.

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Example

Ìàíèïóëÿòîð.swf

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O0.1

I0.0 I0.1

Датчики

O0.3

I0.2 I0.3

Датчики

СХВАТ

ЦИЛИНДР

O0.2

O0.0

a0 a1

b0 b1

A+ A-

B+ B-

Gripping device

Cylinder

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ЦИКЛОГРАММА РАБОТЫ СХВАТА

ЦИКЛОГРАММА РАБОТЫ ЦИЛИНДРА

B+ B-

A+ A-

a0

a1

b1

b0

Шаг1 Шаг2 Шаг3 Шаг4Step 3Step 2Step 1 Step 4

Gripping device

Cylinder

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Sensors

Steps 1 2 3 4

a0 1 0 0 0

a1 0 1 1 0

b0 1 1 0 0

b1 0 0 1 1

Commands

A+ 1 0 0 0

A- 0 0 1 0

B+ 0 1 0 0

B- 0 0 0 1

0 1 0 1

0 1 0 1

0 1 0 1

0 1 0 1

A a a b b

B a a b b

A a a b b

B a a b b

0 0

1 0

1 1

0 1

A a b

B a b

A a b

B a b

0

1

1

0

A b

B a

A b

B a

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FST 4.10

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SensorsSensors

Contact

Inductive

Capacitor

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Application AreasApplication Areas

The right product for the right demands …

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Pneumatic processing centersPneumatic processing centers

Figure. 5.1. The scheme of Figure. 5.1. The scheme of the pneumatic machining the pneumatic machining centercenter

Figure 5.2. The scheme of the pneumatic Figure 5.2. The scheme of the pneumatic processing center for material’s sawing: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

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ApplicationApplication CharacteristicsCharacteristics SchemeScheme ApplicationApplication CharacteristicsCharacteristics

SchemeScheme 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

devices Corrosion preventing

Tightness

Small consumption of working gas

Sorting levers

Big working efforts and acceleration


Amortization of working loadings

Walking

platforms Good dynamics


Small weight

Ease of positioning

Elevating devices

Big working efforts and acceleration

Amortization of working loadings


Counterbalancing

devices

Adjustment of elasticity

Adaptibility of characteristics

Smoothness of job

Small weight

Table: Scopes of systems with pneumatic musclesTable: Scopes of systems with pneumatic muscles

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BatchingBatching

Figure 5.3. The scheme of batching:Figure 5.3. The scheme of batching:1 – tank; 2 – fluid; 3 – a lever with a ladle; 4 - power

cylinder; 5 – accepting chamber

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Figure 5.4.

RoboticsRobotics

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RoboticsRobotics

Figure 5.5. The scheme of the mobile robot: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

Figure 5.6Figure 5.6

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Figure 5.7. The scheme of the Figure 5.7. The scheme of the mobile robot with vertical mobile robot with vertical

displacement:displacement:1 - longitudinal movement module; 2 - rotating movement module; 3 –

console; 4,5 - vacuum gripping devices; 6,7 - elevating cylinders; 8

–trajectory of turn

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QuestionsQuestions??

06.04.2006 1 Hydraulic and Pneumatic Actuators and their Application Areas Elena Ponomareva JASS 2006 – St. Petersburg.

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