Presentation on theme: "APPLIED HYDRAULICS AND PNEUMATICS U5MEA23"— Presentation transcript:
1 APPLIED HYDRAULICS AND PNEUMATICS U5MEA23 Prepared byMr. Jayavelu.S & Mr. Shri HarishAssistant Professor, Mechanical DepartmentVelTech Dr.RR & Dr.SR Technical University
2 UNIT I : Fluid Power Systems and Fundamentals Introduction to fluid powerAdvantages of fluid powerApplication of fluid power systemTypes of fluid power systems,General types of fluidsProperties of hydraulic fluidsFluid power symbolsBasics of HydraulicsApplications of Pascal’s LawLaminar and Turbulent flowReynolds’s numberDarcy’s equationLosses in pipe, valves and fittings
3 Introduction to fluid power Fluid power is a term describing hydraulics and pneumatics technologi es.Both technologies use a fluid (liquid or gas) to transmit power from one location to another.hydraulics, the fluid is a liquid (usually oil),pneumatics uses a gas (usually compressed air).Both are forms of power transmission, which is the technology of converting power to a more useable form and distributing it to where it is needed.The common methods of power transmission are electrical, mechanical, and fluid power.
4 Advantages of fluid power high horsepower-to-weight ratio — You could probably hold a 5-hp hydraulic motor in the palm of your hand, but a 5-hp electric motor might weight 40 lb or more.safety in hazardous environments because they are inherently spark- free and can tolerate high temperatures.force or torque can be held constant — this is unique to fluid power transmissionhigh torque at low speed — unlike electric motors, pneumatic and hydraulic motors can produce high torque while operating at low rotational speeds. Some fluid power motors can even maintain torque at zero speed without overheatingpressurized fluids can be transmitted over long distances and through complex machine configurations with only a small loss in powermulti-functional control — a single hydraulic pump or air compressor can provide power to many cylinders, motors, or other actuatorselimination of complicated mechanical trains of gears, chains, belts, cams, and linkagesmotion can be almost instantly reversed
5 Application of fluid power system ConstructionMiningAgricultureWaste ReductionUtility EquipmentMarineOffshoreEnergyMetal FormingMachine ToolsMilitary & AerospaceOther Applications
6 Types of fluid power systems Fluid transport systemTransport of water from reservoir using pipe linesTransport of oil in pipe to two countries.Fluid power systemOil used in equipments to acquire desire movement.Compressed air in pneumatics for crane movements
7 Properties of hydraulic fluids DensityThe density of a fluid is its mass per unit volu me:Liquids are essentially incompressible Density is highly variable in gases nearly prop ortional to the pressure. Note: specific volume is defined as:
8 Viscosity Cohesion Adhesion Viscosity is a measure of a fluid’s resistance to flo w. It determines the fluid strain rate that is gener ated by a given applied shear stress.CohesionIntermolecular attraction between molecules of same liquidAdhesionAttraction between molecules of liquid and molecules of solid boundary in contact with liquid.
9 Cavitation Capillarity Vapour pressure Cloud of vapour bubble will form when liquid pressure drops below vapour pressure due to flow phenomenonCapillarityLiquid rises into a thin glass tube above or below its general level.Vapour pressurePressure exerted by vapour which is in equilibrium with liquid
10 Compatibility Volatility Corrosiveness Ability of hydraulic fluid to be compatible with the system.VolatilityThe degree and rate at which it will vapourize under given conditions of temperature and pressure.CorrosivenessTendency to promote corrosion in hydraulic system.
17 UNIT 2: Hydraulic SYSTEM COMPONENTS Sources of Hydraulic Powerconstruction and working of pumps – Variable displacement pumpsActuators: Linear hydraulic actuatorsSingle acting and Double acting cylindersFluid motors.Control Components:Direction control valveFlow control valvesElectrical control -- solenoid valves. Relays, Accumulators and Intensifiers.
18 Basic Pump Classifications Hydraulic pumps can be classified using three basic aspects:DisplacementPumping motionFluid delivery characteristics
19 Basic Pump Classifications Displacement relates to how the output of the pump reacts to system loadsPositive-displacement pumps produce a constant output per cycleNon-positive-displacement pumps produce flow variations due to internal slippage
20 Basic Pump Classifications A non-positive-displacement pump has large internal clearancesAllows fluid slippage in the pumpResults in varying flow output as system load varies
22 Basic Pump Classifications The basic pumping motions used in hydraulic pumps are:RotaryReciprocating
23 Basic Pump Classifications Gear pumps are rotary pumpsSauer-Danfoss, Ames, IA
24 Basic Pump Classifications Piston pumps are reciprocating pumpsReciprocating piston movement
25 Basic Pump Classifications In a rotary pump, the pumping action is produced by revolving componentsIn a reciprocating pump, the rotating motion of the pump input shaft is changed to reciprocating motion, which then produces the pumping action
26 Basic Pump Classifications Hydraulic pumps are classified as either fixed or variable deliveryFixed-delivery pumps have pumping chambers with a volume that cannot be changed; the output is the same during each cycleIn variable-delivery designs, chamber geometry may be changed to allow varying flow from the pump
27 Basic Pump Classifications Gear pumps are fixed-delivery pumps
28 Basic Pump Classifications Piston pumps may be designed as variable-delivery pumps
29 Basic Pump Classifications When selecting a pump for a circuit, factors that must be considered are:System operating pressureFlow rateCycle rateExpected length of serviceEnvironmental conditionsCost
30 Pump Design, Operation, and Application Gear pumps are positive-displacement, fixed-delivery, rotary unitsGear pumps are produced with either external or internal gear teeth configurations
31 Pump Design, Operation, and Application Gear pumps are commonly used
32 Pump Design, Operation, and Application Pumping action of gear pumps results from unmeshing and meshing of the gearsAs the gears unmesh in the inlet area, low pressure causes fluid to enter the pumpAs the pump rotates, fluid is carried to the pump discharge areaWhen the gears mesh in the discharge area, fluid is forced out of the pump into the system
33 Pump Design, Operation, and Application Gear pumps are available in a wide variety of sizesFlow outputs from below 1 gpm to 150 gpmPressure rating range up to 3000 psi
34 Pump Design, Operation, and Application The gerotor pump design is an internal- gear pumpUses two rotating, gear-shaped elements that form sealed chambersThe chambers vary in volume as the elements rotateFluid comes into the chambers as they are enlarging and is forced out as they decrease in size
35 Pump Design, Operation, and Application The gerotor is a common internal-gear design
36 Pump Design, Operation, and Application Gerotor operation
37 Pump Design, Operation, and Application Gerotor operation
38 Pump Design, Operation, and Application Gerotor operation
39 Pump Design, Operation, and Application Gerotor operation
40 Pump Design, Operation, and Application Vane pumps are positive-displacement, fixed or variable delivery, rotary units.Design is commonly used in industrial applicationsDelivery can range up to 75 gpmMaximum pressure of about 2000 psi
41 Pump Design, Operation, and Application Vane pump consists of a slotted rotor, fitted with moveable vanes, that rotates within a cam ring in the pump housingRotor is off center in the ring, which creates pumping chambers that vary in volume as the pump rotatesAs chamber volume increases, pressure decreases, bringing fluid into the pumpAs volume decreases, fluid is forced out into the system
42 Pump Design, Operation, and Application Operation of a typical vane pump
43 Pump Design, Operation, and Application Parts of a typical vane pump
44 Pump Design, Operation, and Application Vane pump may be pressure unbalanced or pressure balancedUnbalanced has only one inlet and one discharge, which places a side load on the shaftBalanced has two inlets and two discharges opposite each other, creating a pressure balance and, therefore, no load on the shaft
45 Pump Design, Operation, and Application Piston pumps are positive-displacement, fixed- or variable-delivery, reciprocating unitsSeveral variationsMany provide high volumetric efficiency (90%), high operating pressure (10,000 psi or higher), and high-speed operation
46 Pump Design, Operation, and Application A basic piston pump consists of a housing that supports a pumping mechanism and a motion-converting mechanismPumping mechanism is a block containing cylinders fitted with pistons and valvesMotion converter changes rotary to reciprocating motion via cams, eccentric ring, swash plate, or bent-axis designsRotating the pump shaft causes piston movement that pumps the fluid
47 Pump Design, Operation, and Application Piston pump classification is based on the relationship between the axes of the power input shaft and piston motionAxialRadialReciprocating
48 Pump Design, Operation, and Application Axial piston pumps use two design variations:InlineBent axis
49 Pump Design, Operation, and Application Inline has the cylinder block and pistons located on the same axis as the pump input shaftPistons reciprocate against a swash plateVery popular design used in many applications
50 Pump Design, Operation, and Application An inline axial-piston pump
51 Pump Design, Operation, and Application Bent axis has the cylinder block and pistons set at an angle to the input shaftGeometry of the axis angle creates piston movementConsidered a more rugged pump than inlineManufactured in high flow rates and maximum operating pressures
52 Pump Design, Operation, and Application A bent-axis axial-piston pump
53 Pump Design, Operation, and Application Radial piston pumps have the highest continuous operating pressure capability of any of the pumps regularly used in hydraulic systemsModels are available with operating pressure ratings in the 10,000 psi range
54 Pump Design, Operation, and Application Two variations of radial piston pumps:Stationary-cylinder design uses springs to hold pistons against a cam that rotates with the main shaft of the pumpRotating-cylinder design uses centrifugal force to hold pistons against a reaction ringWhen the main shaft is rotated, each piston reciprocates, causing fluid to move through the pump
55 Pump Design, Operation, and Application A stationary-cylinder radial-piston pump
56 Pump Design, Operation, and Application Large, reciprocating-plunger pump designs were widely used when factories had a central hydraulic power sourceToday, plunger pumps are typically found in special applications requiring high- pressure performance
57 Pump Design, Operation, and Application Screw pumps have pumping elements that consist of one, two, or three rotating screwsAs the screws rotate, fluid is trapped and carried along to the discharge of the pumpThe design of screw pumps allows them to operate at a very low noise level
58 Pump Design, Operation, and Application A typical screw pump
59 Pump Design, Operation, and Application The lobe pump is a close relative of the gear pumpTwo three-lobed, gear-shaped units are often used to form the pumping elementOutput flow is larger than a gear pump of comparable physical size because of pumping chamber geometryLower pressure rating than gear pumpsTend to have a pulsating output flow
60 Pump Design, Operation, and Application Operation of a lobe pump
61 Pump Design, Operation, and Application Centrifugal pumps are non-positive- displacement unitsUse centrifugal force generated by a rotating impeller to move fluidLarge clearances between the impeller and the pump housing allow internal pump slippage when resistance to fluid flow is encountered in the systemTypically used in hydraulic systems as auxiliary fluid transfer pumps
62 Pump Design, Operation, and Application Operation of a centrifugal pump
63 Pump Design, Operation, and Application Propeller and jet pumps are non-positive- displacement pumpsSometimes used to transfer fluid within hydraulic systemsPropeller pump consists of a rotating propeller-shaped pumping elementJet pump creates flow by pumping fluid through a nozzle concentrically located within a venturi
64 Pump Design, Operation, and Application Construction of a propeller pump
65 Pump Design, Operation, and Application Construction of a jet pump
87 Piston type reciprocating compressor Fig shows single-acting piston actions in the cylinder of a reciprocating compressor.The piston is driven by a crank shaft via a connecting rod.At the top of the cylinder are a suction valve and a discharge valve.A reciprocating compressor usually has two, three, four, or six cylinders in it.
88 Screw compressorScrew compressors are also belong to the positive displacement compressor family.In screw compressors, the compression is accomplished by the enmeshing of two mating helically grooved rotors suitably housed in a cylinder equipped with appropriated inlet and discharge ports
89 Rotary vane compressor The rotor shaft is mounted eccentrically in a steel cylinder so that the rotor nearly touches the cylinder wall on one side, the two being separated only by an oil film at this point.Directly opposite this point the clearance between the rotor and the cylinder wall is maximum.Heads or end-plates are installed on the ends of the cylinder and to hold the rotor shaft.The vanes move back and forth radially in the rotor slots as they follow the contour of the cylinder wall when the rotor is turning.The vanes are held firmly against the cylinder wall by action of the centrifugal force developed by the rotating rotor.In some instances, the blades are spring-loaded to obtain a more positive seal against the cylinder wall.
90 Filter Air In Air Out Louver Filter Element Bowl Sight Gauge Drain Cock
93 Quick Exhaust Valve2Port 2 is connected directly to the end cover of a cylinderPort 1 receives air from the control valveAir flows past the lips of the seal to drive the cylinderWhen the control valve is exhausted, the seal flips to the right opening the large direct flow pathAir is exhausted very rapidly from the cylinder for increased speed21112
94 Unit 4: FLUIDICS & PNEUMATIC CIRCUIT DESIGN Fluidics – Introduction to fluidic devices, simple circuits Introduction to Electro Hydraulic Pneumatic logic circuits, PLC applications in fluid power control, ladder diagramsFluid Power Circuit Design: Sequential circuit design for simple applications using classic, cascade, step counter, logic with Karnaugh- Veitch Mapping and combinational circuit design methods.
104 UNIT 5: FLUID POWER Circuits Speed control circuits, synchronizing circuit, Pneumo hydraulic circuit, Accumulator circuits, Intensifier circuits. Servo systems – Hydro Mechanical servo systems, Electro hydraulic servo systems and proportional valves.Deceleration circuit, hydrostatics transmission circuits, control circuits for reciprocating drives in machine tools, Material handling equipments. Fluid power circuits; failure and troubleshooting.