fluid_power_introductionعربى

7/28/2019 fluid_power_introduction

1/33

Fluid Power Introduction

All Images reprinted with permission of National Fluid Power Association


2/33

Fluid Power Definitions

Fluid PowerThe use

of a fluid to transmit power from one location toanother

() Hydraulics

The use of a liquid flowing under pressure totransmit power from one location to another

PneumaticsThe use of a

gas flowing under pressure to transmit powerfrom one location to another


3/33

/

(


4/33

Basic Fluid Power Components

Reservoir / ReceiverStores fluid

Fluid ConductorsPipe, tube, or hose that allows for flow between

components

Pump / Compressor

Converts mechanical power to fluid power

ValveControls direction and amount

of flow

Actuators

Converts fluid power to mechanical power


5/33

Fluid PowerExamples


6/33

Fluid Power Physics

Energy The ability to do work

Energy Transfer

From prime mover, or input source, to an actuator, or

output device


7/33

Fluid Power Physics

Work Force multiplied by distanceMeasured in foot-pounds

Example:How much work is completed

by moving a 1000 lb force 2

ft?

2000 foot-pounds of work


8/33

Fluid Power PhysicsPower

The rate of doing work

Work over time in seconds

Example:How many units of powerare needed to lift a 1000pound force 2 feet in 2

seconds?

1000 units of power(1000lb x 2ft) / 2 s


9/33

Fluid Power PrinciplesHorsepower

Term used to give relative meaning for

measuring power

Unit measurement of energyHydraulic horsepower is expressed as:

flow(gpm)pressure(psi)Horsepower =1714(constant)


10/33

Fluid Power PrinciplesCalculate the horsepower needed in the system

below to lift a 10,000lb force in 2 s.


11/33

Fluid Power PrinciplesHeat

..

Energy not transferred to work takes the

form of heat energy .


12/33

Fluid Power PrinciplesTorque

Twisting force force x distance (.)()

Measured in foot-pounds

Calculate the torque produced when 10 lb

of force is applied to a 1 ft long wrench.


13/33

Fluid Power Principles

Torque The generated work of a hydraulic or pneumatic

motor X

Motor rpm at a given torque specifies energy

usage or horsepower requirement


14/33

Fluid Power Principles Flow

Makes actuator operation possible

To extend the cylinder, flow must be directed

into port B.

Retracted cylinder


15/33

Fluid Power PrinciplesFlow


Flow is directed into Port B

and cylinder is extended.

To retract the cylinder, flow must be directed

into what port?


16/33

Fluid Power PrinciplesFlow


To retract the cylinder, flow must be directed

into what port?

The cylinder retracts when

flow is directed into Port A.


17/33

Fluid Power PrinciplesRate of Flow

Determines actuator speed

Measured in Liters per second lps)

Generated by a pump


18/33

Fluid Power PrinciplesWith a Given Flow Rate

Actuator volume displacement directlyaffects actuator speed

The less volume to displace, the fasterthe actuatorWill the actuator illustrated below travel the same

speed as it retracts and extends if a constant flow

rate is maintained? No. The actuator will travel faster as itretracts due to less volume caused by

the actuator shaft.


19/33

Fluid Power PrinciplesPressure

The resistance to flow

Pumps produce flow by adding pressure energy to the fluid

- If you restrict the flow from the pump, pressure will result.

All points of resistance in series within a system contribute

to total system pressure, including long runs of pipe,

elbows, etc.


20/33

Fluid Power PrinciplesPascals Law

Relationship between force, pressure, andarea

force = pressure areaforce

pressure =area

forcearea =pressure


21/33

Fluid Power PrinciplesPascals Law

Pressure applied on a confined fluid at rest

is transmitted undiminished in all directions

and acts with equal force on equal areas

and at right angles to them.How much force is exerted on every

square inch of the container wall

illustrated on the right if 10 lb of force is

applied to the one square inch stopper?10 lb

What is the total resulting force acting

on the bottom of the container? 200 lb


22/33

Pascals Law

National Fluid Power Association

Hydraulic Press

10 lb can lift 100 lb

What is the tradeoff?

Fluid Power Principles

Distance


23/33

Fluid Power Schematics

SchematicsLine drawing made up of a series of

symbols and connections that represent

the actual components in a hydraulicsystem


24/33


SymbolsCritical for technical communication

Not language-dependent

Emphasize function and methods ofoperation

Basic Symbols


25/33


Lines


26/33


Reservoirs


27/33


Pumps


28/33


Flow Control Valves


29/33

Directional Control Valves



30/33


Check Valves


31/33


Motors


32/33


Cylinders


33/33

Resources

National Fluid Power Association. (2008). What isfluid power. Retrieved February 15, 2008, fromhttp://www.nfpa.com/OurIndustry/OurInd_AboutFP_WhatIsFluidPower.asp

National Fluid Power Association. (2000). FluidPower Training.

National Fluid Power Association & Fluid PowerDistributors Association. (n.d.). Fluid power: Theactive partner in motion control technology.[Brochure]. Milwaukee, WI: Author

Documents

fluid_power_introductionعربى