MAS-3 Automotive Engines
MAS-3 Automotive Engines
MAS-3 Automotive Engines
AEL2501
Automotive Engines
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Session Objectives
To understand the classification of
automotive engines.
Study the constructional features and
arrangement of various parts of IC engines.
Discus the new developments to improve
the low-end performance of an engine
Understand the lubrication system and
cooling system of an IC engine
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Topics
Introduction to automotive engines
4S, Petrol and Diesel engines
Main engine components
Cooling system
Lubrication system
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Engine classification
Some engine classifications include:
Cylinder arrangement Type of aspiration
In-line*, V engine, opposed Naturally aspirated engine
piston / flat engine Turbo* / super charged engine
Type
yp of fuel burned Number of valve / cylinder
Diesel*
2 valves per cylinder*
Petrol
Multi valve engines
CNG / LPG
Valve location
Dual fuel engine
L head engine
Type of ignition
Compression ignition* I head engine ( OHV)*
Spark ignition
Camshaft location
Number of strokes / cycle Overhead cam engine
4 stroke cycle* Cam in the block engine*
2 stroke cycle Combustion chamber design
Cooling system type Shapes: Pancake, wedge,
Water cooled engine* hemispherical, pent roof, pre-
combustion chamber
Air cooled engine
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In-line Engines
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V- Engines
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Horizontally Opposed
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2. Compression stroke
The inlet and exhaust valves are
closed.
closed
The pistons upward movement
compresses the air to the degree
d
determined
i d by
b the
h compressioni
ratio (16:1 to 24:1).
The air, in this process, heats up to
9000C.
Near the completion of the
compression stroke, the fuel-
injection system injects the fuel at
high pressure (as much as 2000
bar in modern engines) in to hot
compressed air in the CC.
When the cylinder reaches the
TDC, the cylinder capacity is at its
minimum.
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3. Ignition stroke
After the ignition lag (a few
degrees of C/s rotation) the
ignition stroke begins.
The finely atomized and easily
combustible
b ibl diesel
di l fuel
f l
spontaneously ignites and burns.
As a result, the cylinder charge
heats up even more and pressure
in the cylinder rises.
The mass of the fuel injected
(quality based control) determines
the amount of energy released.
The pressure forces the piston
downwards. The C/s drive
translates the KE of the piston into
torque.
torque 12
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4. Exhaust stroke
Just before the piston reaches
the BDC,, the exhaust valve
opens.
opens
The hot pressurized gases flow
out of the cylinder.
The upwards movement of the
piston forces the remaining
exhaust gas out of the cylinder.
cylinder
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Piston Assembly
The piston converts the potential
energy of the combustion gases, into
the kinetic energy that turns the
crankshaft.
The piston is a cylindrical shaped Diesel Engine Piston
hollow part that moves up and down
inside the engine's cylinder.
It has grooves around its perimeter
near the top where rings are placed.
The wrist pin connects the piston to
the connecting rod. The connecting
rod comes up through the bottom of
the piston.
The wrist pin is inserted into a hole
( b
(about half
h lf way up)) that
h goes through
h h
the side of the piston, where it is
attached to the connecting rod.
Pistons are usually made of aluminum
alloy, because it is light and a good
heat conductor.
Petrol Engine Piston
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Engine Block
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Engine Head
The cylinder head is the metal part of the
engine that encloses and covers the
cylinders.
Bolted on to the top of the block, the
cylinder
y head contains combustion
chambers (petrol engine), water jackets
and valves (in overhead-valve engines).
The head gasket seals the passages within
the head-block connection, and seals the Typical Diesel Engine Heads
cylinders as well.
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Typical School
M.S Ramaiah Petrol Engine HeadStudies - Bangalore
of Advanced
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Indirect Injection:
In indirect injection, the fuel is injected into a separate chamber that is connected to the
main chamber above the piston by a narrow passage-way.
When the piston rises toward top-dead-center, the air is forced through the connecting
passage att high
hi h velocity
l it into
i t the
th small ll chamber,
h b calledll d a swirl
i l chamber.
h b
The high velocity air rotates at high velocity in the chamber as fuel is injected.
A glow plug inserted into the chamber helps during cold starting.
This type of system relies on the high velocity air swirl to mix the air so the fuel
injection system can operate at lower pressures and be less expensive.
After the fuel ignites, the combusting mixture pushes back out through the passage-way
where the rise in pressure does work on the piston.
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Direct Injection:
In the direct injection diesel engine, the
fuel is sprayed into the combustion
chamber directly above the piston.
The ppiston usuallyy has a recess or bowl
that is designed to confine the air into a
region that matches the fuel spray
trajectory.
This type of system relies primarily on
the momentum of the fuel spray to mix
the fuel and air.
The indirect injection (IDI) engine is less
efficient than the direct injection (DI)
engine
engine.
This is because the high velocity air
motion in the combustion chamber causes
high heat transfer rates resulting in greater
loss of fuel energy.
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Valve Train
The valve train consists of the valves
and a mechanism that opens and closes
them.
The opening and closing system is
made upp of a camshaft and rocker
arms.
arms
The camshaft has lobes on it that move
the valves up and down. Diesel Engine Cam shaft
Poppet valves
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(Advanced inlet gives more top end power at the expense of low end power, and vice-versa) 25
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Flywheels
A flywheel is bolted to the
crankshaft flange
The flywheel is also fitted
with a ring
w g ge
gear to
owwhich
c thee
starter pinion meshes while
cranking the engine using
starter.
The clutch cover with the
clutch disc are bolted to the
flywheel.
y
In certain diesel engines used
on light vehicle, the flywheel
will be replaced with a DMF
for smoother, vibration free
operation.
operation 27
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Coolants
Ethylene glycol based engine coolant concentrate
40 to 70 percent concentration in water
Effective during both winter and summer in
automotive
i vehicle
hi l cooling
li systems to provide
id
protection against freezing, boiling and corrosion.
A typical coolant fluid used in cooling system
consists essentially of:
ethylene glycol
corrosion inhibitors,
a foam
f suppressor,
sufficient water to dissolve the additives
Can be poured at temperatures as low as zero
degrees -17.8 degrees C.
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Water pump:
A centrifugal pump forces coolant through
the engine block, cylinder head, intake
manifold, hoses and radiator
It is often driven by engine crankshaft
through belt
Radiator
Transfers coolant heat to the outside air
Normally mounted in the front of the engine
Scorpio water pump
Consists:
Radiator core
Radiator tanks
Radiator filler neck
Transmission oil cooler
Radiator drain cock
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Radiator Types
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Closed system
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Thermostat
Senses engine temperature and
controls the coolant flow through
the radiator.
It reduces the coolant flow when W pellet
Wax ll t type
t thermostat
th t t operation
ti
engine is cold and increases as the
engines gets warmer
Wax pellet type is commonly used.
When heated, the pellet expands and
pushes the valve open.
As the pellet and the thermostat cool,
the spring tension overcomes pellet
expansion
i andd the
th valve
l closes
l
The rating of the thermostat is its
operating temperature which is
normally 82 91 degree Centigrade
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SAE Classification
A higher viscosity oil is very thick and resists flow and
vise versa
SAE has established an oil viscosity classification system.
It is a numeric rating in which higher the number,
number higher
the viscosity.
Single-viscosity oil:
Rated and designated for a limited range of operating temperatures.
Its viscosity is not stable as multiviscosity oil
Multiviscosity oil:
Will exhibit operating characteristics of a thin oil light oil when
cold and a thicker, heavier oil when hot.
Although single
single--viscosity oils are available, most engine
oils are multiviscosity oils.Ex:
oils SAE 10W-30
To specify engine oil, both the API service designation and
the SAE viscosity grade are required.
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Oil pump:
Most commonly used oil pumps:
Rotor type
Gear type
Both are positive displacement type
pumps.
The output volume is proportional to
the speed of the pump.
Pump is directly or indirectly driven by
the cam shaft or a gear at the front of
the crankshaft.
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Engine oil galleries:
The oil galleries consist of interconnecting passages
that have been drilled completely through the engine
block during manufacturing.
The oil is routed through these passages to various parts
of the engine
engine.
The crankshaft also contains oil passages to route the
oil from the main bearing to the connecting rod bearing
surfaces.
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Oil filters
All the oil that leaves the pump is directed to the oil filter (Full-flow filter).
This is to ensure that very small particles of dirt and metal carried by the oil
will not reach the close-fitting engine parts.
From filter, oil flows into engines main oil gallery
gallery.
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Example: Commercial vehicle engine
Specifications 6.12TCA 6.12TCE
Euro III, capability for Euro III, capability for
Emissions
Euro IV Euro IV
Configuration 6, Inline 6, Inline
Valves / Cylinder 4 4
Displacement Lts 7.2 7.2
Bore x Stroke mm 105 x 137 105 x 137
Combustion system Direct Injection Direct Injection
Injection system Mechanical Common Rail
Thecombustiontechnologywith4valveper 180 - 210 (132.5 - 260 - 315 (190 - 232)
cylinderandoptimised fuelinjectionsystem Power Output hp (kW) @ rpm
154.5) @ 2200 @ 2200
helpsinachievingthestringentBSIII
emissionswithoutanyaftertreatmentand 97.8 - 112 (960 -
Peak Torque kgf-m (Nm) @ rpm 89.7 (880) @ 1400
notevenEGRsystem. 1100) @ 1250 - 1500
Thesuperiorcombustiontechnology Weight (Dry) kg 540 570
enablestomeetthefuturisticemission
normsofBSIValsowithoutanyafter Dimensions mm
treatmentlikeSCRorCatalyticconvertors. Length 1100 1100
Width 734 734
Height 985 985
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Summary
The classification of IC engines based on various
parameters, and engine applications have been
explained.
The constructional details of the main parts of an
engine like piston assembly, block, head and
valve mechanisms including the recent
developments have been discussed.
The lubrication system and cooling systems of an
IC engine has been explained
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