01 understanding the engine

8/12/2019 01 Understanding the Engine

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Learning bjectives

At the completion of this training, participants shouldbe able to demonstrate an understanding of: Describe how internal combustion engine operate Describe how internal combustion engine s lubricated Understand the lubricant viscosity grade and API

classification

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Contents Modern overheadcam eng ne The main parts Circulatorylubrication system Diesel and gasoline Gasoline and diesel Gasoline vs diesel Gasoline four stroke cycle Diesel four stroke cycle Two stroke cycle Gasoline two stroke cycle Diesel two stroke cycle

Camshaftfour stroke engine) Valves Forced induction Turbo charging Turbo charging with intercooler Pistons Crankshaft bearings The sump Exhaust emissions control Black sludge PCV system Diesel engines - future development

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The Main Parts

CamshaftValves

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Distributor

Crankshaft

Flywheel)E f(onMobil

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Circulatory Lubrication System

Filter

Valve mechanismTiming gears

DipstickSumpDrain plug

KeyA StrainerB BearingC ig end bearingD Little end bearingE Connecting rodF CylinderG PistonH Camshaft bearing

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asolinevs Dieselasoline

Quieter Lighter Faster Better acceleration Lower initial cost Catalyst emissionscontrol

Diesel Better fueleconomy Heavier Longer life Good reliability Catalyst and particulate

trap emissions control

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Diesel Engine DesignsDirect Injection DI) Mostly heavy duty- some PassengerCars PCs) Beginning to replaceIDI for PCs Good fuel economy Lower 2 emissions High pistontemperaturesoil oxidation stabilityimportant)

Indirect Injection 101) High Revving- mainly light duty PC Currently dominant nPC applications Higher fuel consumption Lower Ox HC emissions High soot levelsoil dispersancy important)

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Diesel Engine esigns Injector

Piston

Direct Injection

Precompressionchamber

Piston

Indirect Injection

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Gasoline Four Stroke Cycle

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'Suck'Induction

Air

'Squeeze'Compression 'Bang'Power

Exhaust

'Blow'ExhaustEJf onMobil

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Diesel Four Stroke ycle

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'Suck'Induction

Air

'Squeeze'Compression 'Bang'Power

Exhaust

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'Blow'ExhaustEJf(onMobil 12

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Two Stroke Cycle Ignition methods:

- diesel by compression- gasoline by spark Lubricant introduced via the fuel (gasoline engine) Engines are relatively inexpensive Tend to be noisy

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Gasoline Two troke Cycle

l Exhaust

Pre-inductionand PowerPre-compressionand Exhaust Induction

tCompression

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300C) Deposits may form on thevalve preventing a good seal Oil flow down the valve stem

s critical:- too much can lead to deposits- too little can allow stems tobe contaminatedleading to seizure

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Cam

FollowerSpring

Poppet valve

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Forced nductionTurbochargers and Superchargers Some engines use forced induction to increasecombustion efficiency Achieved by blowing air into the inlet manifoldunder pressureTwo main methods Turbocharger- a turbine air pump driven by exhaust gases Supercharger- a mechanical air pump driven from the crankshaft

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l ~ t i \ LTurbocharging and upercharging

Turbine drivenby exhaust gas

TURBOCHARGING

L IItwB l l

l ::::::::i:: ' Compressordriven by turbine

SUPERCHARGING

Compressor drifrom crankshaft

Air in

Turbos tend to be light, lessexpensive, and use less o theengine's power output.This makes them popular for bothgasoline and diesel applications.

Exhaust;,. ~ ~gasesSuperchargers operate well even at slow speed.

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Turbocharger with ntercooler Turbos increase specific power output of

engines by improving 'breathing'- more oxygen available Cooling air prior to inductionincreases its densitymaking further oxygenavailable thus a further. .1ncrease n power

Specific PowerComparisons:NA 15kW/L; TC - 30kW/L;TCIIC - 40kW/L

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Turbocharger Cut-Away

Intake Air

The shaft turns o high speed bearings This is a critical areafor lubrication



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istons High temperature zone (200-300C390-570F) n the ring pack, with highertemperatures on the piston crown High temperatures n diesels give pistondeposits from burnt oil/fuel

- Oil is designed to minimize these Most engine friction occurs here

- Engine design plus optimizedlubrication can be used toimprove fuel economy

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Piston

RingPack

Connecting(Con) Rod

Crankshaft ConnectingRod earings

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Pistonsticking Rings

Deposits can build up aroundthe rings preventing their movementleads to loss of power, nincrease in combustion gasleakage ('blow-by') and highoil consumptionExcessive Wear Upper piston deposits- particularly in diesel engines,can abrade the cylinder wall,wearing away the honing marks('bore polishing')

Ringsosits/Wear

Skirt



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vBearingsBearing Locations:

- Crankshaft, camshaft, connecting rods and pistons

They consist o soft metal bearing shells inside which thesupported shaft rotates Oil is pumped under pressure into theshell through oil holes n the crankshaft,and/or the connecting rod Typically, bearings are coated withcopper, over laid with lead, over laid

with a lead/tin matrix Lubrication is needed to prevent contact between the shaftand the bearing shells

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ump The oil is held n a reservoirat the bottom o the cylinder

block known as the sump Oil is pumped from herearound the engine andfalls back under gravityto be recycled

Oil pump inta

Dipstick

SumpOil

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01 understanding the engine

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