RADIAL PISTON PUMP…By Vardan sedha

CONTENTS…

TYPES

DEFINATION

REQUIREMENT

APPLICATIONS

COMPARISON

PRINCIPLE

WORKING

OUTPUT

WHAT IS A PUMP

A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action. Pumps can be classified into three major groups according to the method they use to move the fluid: direct lift, displacement, and gravity pumps.

Pumps operate by some mechanism (typically reciprocating or rotary), and consume energy to perform mechanical work by moving the fluid. Pumps operate via many energy sources, including manual operation, electricity, engines, or wind power, come in many sizes, from microscopic for use in medical applications to large industrial pumps.

*******

Pumping power

where,

Δp is the change in total pressure between the inlet and outlet

Q, the volume flow-rate of the fluid

η is the pump efficiency

And..

Pump efficiency

• Pump efficiency is defined as the ratio of the power imparted on the fluid by the pump in relation to the power supplied to drive the pump.

• Its value is not fixed for a given pump, efficiency is a function of the discharge and therefore also operating head.

• For centrifugal pumps, the efficiency tends to increase with flow rate up to a point midway through the operating range (peak efficiency) and then declines as flow rates rise further.

• Pump performance data such as this is usually supplied by the manufacturer before pump selection.

HISTORY…

200 BC- Water organ, an air pump with valves on the bottom, a tank of water in between them and a row of pipes on top. This is the principal design that is now known as the reciprocating pump.

1588 Sliding vane water pump technology

1593 -Gear pump

1675 -Packed plunger pump, capable of raising great quantities of water with far less proportion of strength than a chain or other pump. The piston had a leather seal.

1687 Centrifugal pump

HISTORY…

1738 - In fluid dynamics, Bernoulli's principle states that for an inviscidflow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy. The principle is applied to various types of fluid flow and is loosely known as Bernoulli's equation.

1782 James Watt—who invented the steam engine's connecting rod crank mechanism, which made it possible to convert the piston's reciprocating motion into rotary motion—designs an oscillating piston machine in which a wing-shaped rotary blade made a near complete revolution uncovering inlet ports in a chamber separated by a curved radial wall

HISTORY…

Modern screw pump

All-metal pump

Curved vane centrifugal pump

Wood screw pump

Direct motor-driven reciprocating pump

2006 - High-tech EMTEC-A pump designed specifically for moving emulsions and cooling lubricants.

2010 - First structural composite anti-heeling pump manufactured for NCL Cruise lines

LATEST DISCOVERIES..WHAT IS ANTI-HEELING SYSTEM ON SHIPS?

• When the ship tilts on any of its sides i.e. port or starboard and doesn’t return back to its upright position, it is known as heeling of the vessel.

• the most common cause is uneven cargo loading and unloading

• The anti heeling system of a ship automatically detects the heeling angle of the ship and compensates the same by aid of pumps.

In this system, ballast tanks are internally connected to each other by means of pipe lines, automatic valves and control systems. When the ship heels to any of the sides, the heeling sensor sends the signal for change of ships angle with respect to the ship’s upright position to the master control panel. This change in heeling angle is compensated by methods of auto transferring the water from the heeled side to the other side of the ship, making the vessel upright.

BALLASTING..

• When no cargo is carried by the ship, the later becomes light in weight, which can affect its stability. For this reason, ballast water is taken in dedicated tanks in the ship to stabilize it. Tanks are filled with ballast water with the help of high capacity ballast pumps and this process is known as Ballasting.

DEBALLASTING…

• However, when the ship is filled with cargo, the stability of the ship is maintained by the weight of the cargo itself and thus there is no requirement of ballast water. The process of taking out ballast water from the ballast tanks to make them empty is known as de-ballasting.

Gear Pumps

Off-

centered

internal

gear pump

Centered

internal

gear pump

/ gerotor

pump

Screw

pump

Vane

pump

Radial Piston

Pumps

External

gear

pump

Axial Piston Pumps

Tilting

block

Stationar

y

cylinder

block

Rotating

cylinder

block

Tilting

cam

plate

APPLICATION....

Pumping water from wells

Aquarium filtering, pond filtering and aeration

In the car industry for water-cooling and fuel injection

In the energy industry for pumping oil and natural gas or for operating cooling towers

In the medical industry, pumps are used for biochemical processes and in biomimicry such as creation of artificial heart.

TYPES…

Positive displace

ment pump

valvelesspumps

steam pumps

gravity pumps

velocity pumps

impulse pumps

FURTHER CLASSIFICATION….

Positive displacement

pump

Reciprocating type

Linear type

Rotary type

Plunger pumps Radial piston pumps

Piston pumps Diaphragm

pumps

Reciprocating type

RADIAL PISTON PUMP….

A radial piston pump is a form of hydraulic pump. The working pistons extend in a radial direction symmetrically around the drive shaft, in contrast to the axial piston pump.

These are made up of valve-controlled pump cylinders arranged in radial star-shape. They supply pressurized oil reliably up to 700 bar.

They can produce a very smooth flow under extreme pressure. Generally they are variable-displacement pumps.

CONT….

In variable models, flow rate changes when the shaft holding the rotating pistons is moved with relation to the casing (in different models either the shaft or the casing moves). Output can also be varied by changing the rotation speed.

An odd number of pistons is always used to smooth the hydraulic balance. These pumps revolve at speeds up to about 1200 RPM.

CONSTRUCTION…

The stroke of each piston is caused by an eccentric drive shaft or an external eccentric tappet.

• 1 pump piston

• 2 cam

• 3 slip ring

• 4 valve piston spring (coil)

• 5 valve plug

• 6 band spring (circumferential)

• 7 Valve stem

• 8 Impact plate

• 9 Section

• 10 Valve spring (around stem)

• 11 Location

• 12 Annular collection channel

• 14 Pressure passage

• 16 Suction port

DELIVERY STROKE SUCTION STROKE

VARIATIONS…

o When filling the workspace of the pumping pistons from "inside" (e.g., over a hollow shaft) it is called an inside impinged (but outside braced) radial piston pump.

o If the workspace is filled from "outside" it's called an outside impinged radial piston pump (but inside braced).

WITH INTERNAL ECCENTRIC SHAFT…

WORKING PHASES…

PROPERTIES….

• Long life, low wear because of good lubrication

• Higher noise, uneven delivery

• Sensitive to contamination

• Excentricity can be governed, over 0 too

• For motor applications mostly at low speed, 1-10 rpm

• Relative bulky

FUNCTION…

The outer ring for bracing of the pumping pistons is in eccentric position to the hollow shaft in the center. This eccentricity determines the stroke of the pumping piston.

The piston starts in the inner dead center (IDC) with suction process. After a rotation angle of 180° it is finished and the workspace of the piston is filled with the to moved medium. The piston is now in the outer dead center(ODC). From this point on the piston displaces the previously sucked medium in the pressure channel of the pump.

ARRANGEMENT…

CHARACTERISTICS…

high efficiency

high pressure (up to 1,000 bar)

low flow and pressure ripple (due to the small dead volume in the workspace of the pumping piston)

low noise level

very high load at lowest speed due to the hydrostatically balanced parts possible

no axial internal forces at the drive shaft bearing

high reliability

DISADVANTAGES..

1) A disadvantage are the bigger radial dimensions in comparison to the axial piston pump, but it could be compensated with the shorter construction in axial direction.

2) The disadvantage of radial piston pumps of this design is the generation of noise which can extend to an excessive point. These noises arise from the ejection of the oil from the necessary lifting of the band spring. The band spring, when lifted, must push against the pressurized oil standing in the annular collection channel. This burdens the ejection of the oil by the delivering piston and is hence a party to pressure peaks in the cylinder boring which, in the first place, make lifting of the band spring possible.

APPLICATIONS…

Due to the hydrostatically balanced parts it is possible to use the pump with various hydraulic fluids like mineral oil, biodegradable oil, HFA (oil in water), HFC (water-glycol), HFD (synthetic ester) or cutting emulsion. That implies the following main applications for a radial piston pump:

• machine tools (e.g., displace of cutting emulsion, supply for hydraulic equipment like cylinders)

• high pressure units (HPU) (e.g., for overload protection of presses)

• test rigs

• automotive sector (e.g., automatic transmission, hydraulic suspension control in upper-class cars)

• plastic- and powder injection moulding

• wind energy

REFRENCES...

• en.wikipedia.org

• www.dta.eu

• www.slideshare.net

• Patent US6626647 - Radial piston pump - Google Patents

• www.animatedsoftware.com

• www.marineinsight.com