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Semelhante a Hydraulic Pumps (Types of Pumps and There Properties)
Semelhante a Hydraulic Pumps (Types of Pumps and There Properties) (20)
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Hydraulic Pumps (Types of Pumps and There Properties)
- 1. Mohammad Azam Khan PUMPS PUMPS 1 Mohammad Azam Khan M.Tech. Industrial & Production
- 2. Mohammad Azam Khan HYDRAULIC PUMP PUMPS 2 • A pump is the heart of the hydraulic system,convert mechanical energy into hydraulic energy. • Main purpose of the pump is to create the flow of oil through the system & thus assist transfer of power & motion. • The combined pumping and driving motor unit is known as hydraulic pump. • The hydraulic pump takes hydraulic fluid (mostlysome oil) from the storage tank and delivers it to the rest of the hydraulic circuit. • In general,the speed of pump is constant and the pump delivers an equal volume of oil in each revolution.
- 3. Mohammad Azam Khan HYDRAULIC PUMP PUMPS 3 • The hydraulic pumps are characterizedby its flow rate capacity, power consumption,drive speed, pressure deliveredat the outlet and efficiencyof the pump. • The pumps are not 100% efficient. • The efficiencyof a pump can be specifiedby two ways: – One is the volumetric efficiency which is the ratio of actual volume of fluid delivered to the maximum theoretical volume possible. – Second is power efficiency which is the ratio of output hydraulic power to the input mechanical/electrical power. • The typical efficiencyof pumps varies from 90-98%.
- 4. Mohammad Azam Khan HYDRAULIC PUMP PUMPS 4 • The hydraulic pumps can be of two types: – centrifugal pump – reciprocating pump
- 5. Mohammad Azam Khan CENTRIFUGAL PUMP • Centrifugal pump uses rotational kinetic energy to deliverthefluid. • The rotational energytypically comes from an engine orelectric motor. • The fluid enters the pump impeller along or near to the rotating axis, accelerates in the propeller andflungout to the peripheryby centrifugal forceas shown in figure. • In centrifugal pump the delivery is not constant and varies according to the outlet pressure. PUMPS 5
- 6. Mohammad Azam Khan CENTRIFUGAL PUMP PUMPS 6 • These pumps are not suitable for high pressure applications and are generallyused for low-pressure and high-volume flow applications. • The maximum pressure capacityis limitedto 20-30 bars. • Most of the centrifugal pumps are not self-primingand the pump casing needs to be filledwith liquid before the pump is started.
- 7. Mohammad Azam Khan RECIPROCATING OR POSITIVE DISPLACEMENT PUMP • The reciprocating pump is a positive plunger pump. It is also known as positive- displacement pump or piston pump. • It is often used where relatively small quantity is to be handled and the delivery pressure is quite large. The construction of these pumps is similar to the four stroke engine as shown in figure. PUMPS 7
- 8. Mohammad Azam Khan RECIPROCATING OR POSITIVE DISPLACEMENT PUMP PUMPS 8 • The crank is driven by some external rotatingmotor. • The piston of pump reciprocates due to crank rotation.The piston moves down in one half of crank rotation,the inlet valve opens and fluid enters into the cylinder. • In second half crank rotationthe piston moves up, the outlet valve opens and the fluid moves out from the outlet. • At a time,only one valve is opened and another is closed so there is no fluid leakage. • Depending on the area of cylinder the pump delivers constant volume of fluid in each cycle independent to the pressure at the output port.
- 9. Mohammad Azam Khan CLASSIFICATION OF HYDRAULIC PUMPS • These are mainlyclassifiedintotwo categories: Pump Hydrostatic (Positive displacement) Hydrodynamic (Non-Positive displacement) PUMPS 9
- 10. Mohammad Azam Khan POSITIVE DISPLACEMENT PUMPS PUMPS 10 • This pump ejects fixed quantity of fluid per revolutionof the pump shaft. The pump outlet flow is constant & is not depended on the system pressure. So they are suited for fluid power system. • Positive displacement pumps must be protected against overload. The reason is that, it continues to eject fluid (even though it has no place to go) causing an extremelyrapid build up of pressure. • Example: Gear pump, Vane pump, piston pump.
- 11. Mohammad Azam Khan ADVANTAGES OF POSITIVE DISPLACEMENT PUMPS PUMPS 11 • PD pumps are widely used in hydraulic system • They generate high pressure • They are relativelysmall & enjoy very high power to weight ratio. • They have greater flexibilityof performance under varying speed pressure requirement.
- 12. Mohammad Azam Khan CONSTRUCTION & PRINCIPAL OF PD PUMPS.. PUMPS 12 • Reciprocatingpump are generallycylinders with operatingas a pump. • They are available in various size, shape & driving mechanisms.Due to high pressure they are used for specializedapplications. • A pump using this principle is known as piston pump. • Rotary pump are most common in oil hydraulics system when low to medium pressure is the prime consideration. – The 3 prime types are: – 1) Gear, 2) Vane, 3) Screw
- 13. Mohammad Azam Khan GEAR PUMPS PUMPS 13 • Gear pump is a robust and simple positive displacement pump.It has two meshed gears revolving about their respective axes. • The rigid design of the gears and houses allow for very high pressures and the abilityto pump highly viscous fluids. • They are suitable for a wide range of fluids and offer self - priming performance.
- 14. Mohammad Azam Khan GEAR PUMPS PUMPS 14 • Based upon the design,the gear pumps are classified as: – External gear pumps – Lobe pumps – Internal gear pumps – Gerotor pumps
- 15. Mohammad Azam Khan EXTERNAL GEAR PUMP PUMPS 15 • External gear pumps have two matinggear in a closed fitted housing. One of the gear is connected to a drive shaft connected to the prime mover. • The 2nd one, the follower gear is driven as it meshes with the driver gear.
- 16. Mohammad Azam Khan INTERNAL GEAR PUMP PUMPS 16
- 17. GEROTOR pumps
- 18. LOBE pumps
- 19. Mohammad Azam Khan HOW EXTERNAL GEAR PUMP WORK ! PUMPS 19
- 20. Mohammad Azam Khan GENERALLY GEAR PUMPS ARE USED TO PUMP PUMPS 20 • Petrochemicals:Diesel oil, crude oil, lube oil etc. • Chemicals: Sodium silicate,acids,plastics,mixed chemicals etc. • Paint and ink • Resins and adhesives • Pulp and paper: acid, soap, lye, black liquor, lime,sludge etc. • Food: Chocolate, cacao butter, fillers,sugar, vegetable fats and oils, animal food etc.
- 21. Mohammad Azam Khan PISTON PUMPS PUMPS 21 • Piston pumps are meant for the high-pressure applications. These pumps have high efficiency and simple design and needs lower maintenance. • These pumps convert the rotary motion of the input shaft to the reciprocating motion of the piston. These pumps work similar to the four stroke engines. • They work on the principle that a reciprocating piston draws fluid inside the cylinder when the piston retracts in a cylinder bore and discharge the fluid when it extends. • These pumpsare positive displacement pump and can be used for both liquids and gases.
- 22. • Piston pumps are basicallyof two types: – Axial piston pumps • Bent axis piston pumps • Swash plate axial piston pump – Radial piston pumps Mohammad Azam Khan PISTON PUMPS TYPES PUMPS 22
- 23. • Hand pumps are basicallyof two types: – Single Stroke – Double Stroke Mohammad Azam Khan HAND PUMPS PUMPS 23
- 24. Mohammad Azam Khan AXIAL PISTON PUMP PUMPS 24 • Axial piston pumps are positive displacement pumps which converts rotary motionof the input shaft into an axial reciprocatingmotionof the pistons. • These pumps have a number of pistons (usuallyan odd number) in a circular array within a housing which is commonly referred to as a cylinder block, rotor or barrel.
- 25. BENT AXIS PUMP Bent axis pumps, axial piston pumps and motors using the bent axis principle, fixed or adjustable displacement, exists in two different basic designs. The Thoma-principle (engineer Hans Thoma, Germany, patent 1935) with max 25 degrees angle and the Wahlmark-principle (Gunnar Axel Wahlmark, patent 1960) with spherical-shaped pistons in one piece with the piston rod, piston rings, and maximum 40 degrees between the driveshaft centreline and pistons (Volvo Hydraulics Co.). These have the best efficiency of all pumps. Although in general the largest displacements are approximately one litre per revolution.
- 26. RADIAL PISTON/PLUNGER PUMP A radial piston pump is a form of hydraulic pump. The working pistons extend in a radial directionsymmetrically around the drive shaft, in contrast to the axial piston pump.
- 29. SCREW PUMP Screw Pump (fixed displacement) consist of two Archimedes’ screw that intermesh and are enclosed within the same chamber. These pumps are used for high flows at relatively low pressure (max 100 bars (10,000 kPa)). They were used on board ships where a constant pressure hydraulic system extended through the whole ship, especially to control ball valves but also to help drive the steering gear and other systems. The advantage of the screw pumps is the low sound level of these pumps; however, the efficiencyis not high.
- 30. The major problem of screw pumps is that the hydraulic reaction force is transmitted in a direction that's axially opposed to the direction of the flow. There are two ways to overcome this problem: 1.put a thrust bearing beneath each rotor; 2.create a hydraulic balance by directing a hydraulic force to a piston under the rotor. Types of screw pumps: 1.single end 2.double end 3.single rotor 4.multi rotor timed 5.multi rotor untimed. SCREW PUMP
- 31. Mohammad Azam Khan COMBINATION PUMP PUMPS 31 • Two basic requirements for load liftingor load applying by a hydraulic ram. • First, there is a need of large volume of fluid at a low pressure when the cylinder extends or retracts.The low pressure is requiredto overcome the frictional resistance. • The second requirement is that a high pressure is needed, when the load is gripped.
- 32. Mohammad Azam Khan COMBINATION PUMP PUMPS 32
- 33. Mohammad Azam Khan COMBINATION PUMP PUMPS 33 • In this system two separate pumps are driven by a common electrical motor. • Pump P1 is a high pressure low volume pump and pump P2 is a high volume low pressure pump. • The hydraulic system is associatedwith relief valves RV1 and RV2 and a one-way check valve CV1. • This kind of arrangement allows the fluid flow from left to right. • This kind of arrangement saves energy as the large volume of fluidfrom pump P2 is returnedto the tank at a very low pressure, and only a small volume of fluidfrom pump P1 is returnedat a high pressure.