Presentation on theme: "Hydraulic and Pneumatic Actuators and their Application Areas"— Presentation transcript:
1Hydraulic and Pneumatic Actuators and their Application Areas Elena PonomarevaJASS 2006 – St. Petersburg
2Figure A. Automatic Pneumatic Drive: IntroductionFigure 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
4Gas Laws The combined gas law Boltzmann’s equation The ideal gas law P is the pressure in atmospheres (atm) or kilopascals (kPa);V is the volume in litersn is the number of moles of gasR is the ideal gas constant in L atm/mol K or Pa m³/mol KT is the temperature in kelvins.Boltzmann’s equationThe strings and are the Kinetic Energym refers to the mass of one atom< c2 > refers to the average of c2k refers to the Boltzmann constantT refers to the temperature of the surroundings
5Classification 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.
6Diaphragm 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 rodFigure 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
7Pneumatic 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.
8Pneumatic Power Cylinders A double acting pneumatic cylinder has two- directed powered motion, with pressure on both sides.
10Pneumatic Power Cylinders Optimal rangeGood running performance and long service life thanks to smooth, hard cylinder borePiston rod and cylinder barrel made of stainless steelMore than the standardRound cylinders with piston diameters from 8 to 25 mm conform to ISO 6432, DIN ISO Variants are based on these standards. The series is not repairable.The cap is swaged onto the barrel.FunctionalThree different end caps mean numerous functional and spacesaving designsVariantsNon-rotatingThrough piston rodWith or without position sensingCushioning non-adjustable at either end or cushioning adjustable at both endsFurther piston rod variants
11Pneumatic Power Cylinders Double-acting double-rod cylinder – double-acting cylinder with a piston rod extending form each end.The piston rods are connected with the same piston. Double-rod cylinders provide equal force and speed in both directions.
12Pneumatic Power Cylinders Fast or slow valve actuationPosition sensingInternal air channels eliminate protruding tubing and attachments, and thus also harmful accumulation of contaminantsSuitable for manual on-site use, as well as automatic operationOpening and closing actuated via flange-mounted solenoid valve with port pattern to Namur, or via valve terminals with a choice of 30 different fieldbus protocolsSturdy and reliable, even in aggressive environmentsHighly corrosion resistantFesto Copac Linear Actuator
13Pneumatic Power Cylinders Ideal for vertical useBall-bearing circulating guide system for a long service life when operated verticallyDouble piston rod for a high level of force in spite of a flat designCompact dimensionsSymmetric geometryLow weightWide variety of mounting optionsThe 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).
14Pneumatic Power Cylinders The 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.
15Pneumatic Power Cylinders Tandem cylinders ADVUTA 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.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.
16Pneumatic 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.Figure 1.3. The scheme of the shot pneumocylinder:A, b, c – cavities; 1, 3, 4 – channels; 2 - aperture
17Pneumatic 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.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
18Pneumatic Power Cylinders All settings accessible from one side:Precision end-position adjustmentPosition of proximity sensorsMounting of driveSpeed regulationPneumatic end-positioncushioningSealing systemCompact – fitting length relative to strokeLoads and devices can be directly mounted on the slide
19Pneumatic Power Cylinders Figure 1.5. The hose pneumocylinder:1 – hose;2 - rollers of the carriage;3 - control valve;B
20Pneumatic 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 mmWith adjustable end-position cushioning at both ends for piston ∅ 40 to 100 mmFigure 1.6 Rotary pneumoactuator:1, 2, 5 - channel; piston; 4 - chain transfer; A - cavity; Рip - pressureFor contactless position sensingBacklash-free power transmissionWide choice of mounting options
22Pneumatic 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.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
23Pneumatic Power Cylinders Figure 1.9 Lateral force Fq as a function of stroke length l .
24Pneumatic Power Cylinders Figure 1.10 Pneumomuscle:1 - internal elastic tube; 2 - braid; 3, 4 – covers; 5 – feeding channelFigure 1.12 Geometrical parameters of reduced pneumomuscles:1 - braid; 2 - internal elastic tube;3 – pantograph’s cellFigure 1.11 Comparative characteristics of output efforts of the power cylinder and the pneumomuscle:1 - power cylinder; 2 - pneumomuscle
25Pneumatic Power Cylinders Figure 1.13 The artificial muscle:1 – casing; 2 - elastic tube; 3 – thermoelement; 4 – filler; electric leading-out wires
26Pneumatic Power Cylinders Figure 1.14 The electropneumatic actuator:1 - amplifier of direct current; electromechanical converter; 3 - choker; 4 - nozzles, 5 - throttles, 6, 7 - executive pneumocylinders, 8, 9 - feedback sensors 10 - spring, flywheel
29Advantages and disadvantages compressibility of the airimpossibility to receive uniform and constant speed of the working bodies movementdifficulties in performance at slow speedlimited 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)Advantages:simplicity of realization relatively to small back and forth motions;sophisticated transfer mechanisms are not requiredlow costhigh speed of movingease at reversion movementstolerance to overloads, up to a full stop.high reliability of workexplosion and fire safetyecological purityability to accumulation and transportation
31Bernoulli's Equation The original form of Bernoulli's equation v = fluid velocity along the streamlineg = acceleration due to gravity on Earthh = height from an arbitrary point in the direction of gravityp = pressure along the streamlineρ = fluid densityThe second, more general form of Bernoulli's equationφ is the gravitational potential energy per unit massω is the fluid enthalpy per unit massε is the fluid thermodynamic energy per unit mass
32The Structure of Hydraulic Cylinders Figure 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
33The 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
34The Structure of Hydraulic Cylinders Figure 2.3. The three-high-speed hydraulic cylinder: ,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
35The 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
36The 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
37The 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
38The 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
39Volumetric Hydraulic Actuator Figure 2.8. Hydraulic JackIn 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.
40Volumetric 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
41Volumetric Hydraulic Actuator Figure 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
42Volumetric Hydraulic Actuator Figure 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
43Volumetric Hydraulic Actuator Figure 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
44Volumetric Hydraulic Actuator Figure 2.13 The scheme of a stream divider: — throttles; 2, 3 — apertures; 4 — a piston; 5 — a sleeve; M — a point of division of stream Q on streams Q1, and Q2
45Follower 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 — supportFigure 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 double-shouldered lever
48Advantages 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 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.
57Control SystemsLet'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 schemeExecutive devicesSensors, controllers and operating controlSensors – contacts, inductive, capacitive, optical, hydraulic, pneumatic, PLC.Logical scheme – electrical, pneumatic, hydraulic.Executive devices – hydro- and pneumocylinders, hydro- and pneumomotors and so on.
65Application AreasThe right product for the right demands …
66Application Areas Pneumatic processing centers 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 actuatorFigure The scheme of the pneumatic machining center
67Application Areas Table: Scopes of systems with pneumatic muscles CharacteristicsSchemePlatform positioningGood dynamicsLarge working effortsAccuracy of positioningSimplicity of a designBrake actuatorGood controllabilityAbsence of friction of restSimplicity of a design and operationTightening devicesThe big efforts of a clipCompactnessSmall weightUnderwater devicesCorrosion preventingTightnessSmall consumption of working gasSorting leversBig working efforts and accelerationAmortization of working loadingsWalking platformsEase of positioningElevating devicesCounterbalancing devicesAdjustment of elasticityAdaptibility of characteristicsSmoothness of job
68Figure 5.3. The scheme of batching: Application AreasBatchingFigure 5.3. The scheme of batching:1 – tank; 2 – fluid; 3 – a lever with a ladle; 4 - power cylinder; 5 – accepting chamber
70Application Areas Robotics 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
71Figure 5.7. The scheme of the mobile robot with vertical displacement: Application AreasFigure 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