Download - Engine components and classification
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 1/44
CHAPTER 1 –ENGINE
COMPONENTS &
CLASSIFICATION
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 2/44
SUMMARY The topic covers basic theoretical knowledge
and understanding of engine components,
classifications and terminologies. Areas
involving engine construction, operatingprinciples and valve train
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 3/44
SYLLABUS Understand engine construction
Explain various types of internal combustion
engines construction and operation: twostroke petrol and diesel fourstroke petrol and diesel
rotary!"ankel
Understand basic engine terminologiesExplain basic engine terminologies such as
T#$, %#$, stroke, bore, displacement,
compression ratio etc.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 4/44
Understand cylinder head and valve train
construction&tate the purpose of cylinder head
#escribe various type of valve train: '() '($
*ultivalve
Explain typical valve timing diagram
Explain basic operating principles of: )TE$
*+)E$ ))T+
$&
#))T
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 5/44
INTRODUCTION TO ENGINES Engine provides the power to drive the vehicle-s
wheel.
%iggest part of the engine is the cylinder block.
The cylinder block is a large casting of metalthat is drilled with holes to allow for the
passage of lubricants and coolant through the
block and provide spaces for movement of
mechanical parts.
The block contains the cylinders, which are
round passageways fitted with pistons.
The block houses or holds the maor mechanical
parts of the engine.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 6/44
The cylinder head fits on top of the cylinder
block to close off and seal the top of the
cylinder.
The combustion chamber is an area into which
the airfuel mixture is compressed and burned.
The cylinder head contains all or most of the
combustion chamber. The cylinder head also contains ports through
which the airfuel mixture enters and burned
gases exit the cylinder and the bore for the
sparkplug.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 7/44
The valve train is a series of parts used to
open and close the intake and exhaust ports.
A valve is a movable part that opens andcloses the ports.
A camshaft controls the movement of the
valves.
&prings are used to help close the valves.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 8/44
The upanddown motion of the pistons must be
converted to rotary motion before it can drive
the wheels of a vehicle.
This conversion is achieved by linking the piston
to a crankshaft with a connecting rod.
The upper end of the connecting rod moves
with the piston.
The lower end of the connecting rod is attached
to the crankshaft and moves in a circle.
The end of the crankshaft is connected to the
flywheel.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 9/44
ENGINE CLASSIFICATIONS 'perational cycles. /0 stroke or 1 stroke2
3umber of cylinders. /4,0,5,6,7,89,81
cylinders2
$ylinder arrangement. /lat, inline, )type2 )alve train type. /'($,'(), #'($2
+gnition type /&park, $ompression2
uel type /gasoline, natural gas, methanol,
diesel, propane, fuel cell, electric, hybrid2
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 10/44
ENGINE CONSTRUCTION Types of internal combustion engines
construction:0 &troke petrol and diesel
1 &troke petrol and diesel;otary!wankel
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 11/44
4 STROKE PETROL
+ntake &troke$ompression
&trokeower &troke
Exhaust&troke
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 12/44
INTAKE STROKE The first stroke of the cycle is the intake stroke.
As the piston moves away from top dead e!te" #TDC$, the intake
valve opens.
The downward movement of the piston increases the volume of the
cylinder above it, reducing the pressure in the cylinder. <ow
pressure /engine vacuum2 causes the atmospheric pressure to push amixture of air and fuel through the open intake valve.
As the piston reaches the bottom of its stroke, the reduction in
pressure stops, causing the intake of airfuel mixture to slow down.
+t does not stop because of the weight and movement of the airfuel
mixture.
+t continues to enter the cylinder until the intake valve closes. The
intake valve closes after the piston has reached %otto deade!te" #BDC$.
This delayed closing of the valve increases the volumetric efficiency
of the cylinder by packing as much air and fuel into it as possible.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 13/44
COMPRESSION STROKE The compression stroke begins as the piston starts to
move from %#$.
The intake valve closes, trapping the airfuel
mixture in the cylinder.
The upward movement of the piston compresses the
airfuel mixture, thus heating it up.
At T#$, the piston and cylinder walls form a
combustion chamber in which the fuel will be
burned. The volume of the cylinder with the piston at %#$
compared to the volume of the cylinder with the
piston at T#$ determines the compression ratio of
the engine.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 14/44
PO'ER STROKE The power stroke begins as the compressed fuel
mixture is ignited.
"ith the valves still closed, an electrical spark
across the electrodes of a spark plug ignites the
airfuel mixture.
The burning fuel rapidly expands, creating a
very high pressure against the top of the piston.
This drives the piston down toward %#$. Thedownward movement of the piston is
transmitted through the connecting rod to the
crankshaft.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 15/44
E(HAUST STROKE The exhaust valve opens ust before the piston
reaches %#$ on the power stroke.
ressure within the cylinder causes the exhaust gas to
rush past the open valve and into the exhaust system.
*ovement of the piston from %#$ pushes most of theremaining exhaust gas from the cylinder.
As the piston nears T#$, the exhaust valve begins to
close as the intake valve starts to open.
The exhaust stroke completes the fourstroke cycle. The opening of the intake valve begins the cycle
again.
This cycle occurs in each cylinder and is repeated
over and over, as long as the engine is running.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 16/44
+t takes two full revolutions of the crankshaft
to complete the fourstroke cycle.
'ne full revolution of the crankshaft is e=ualto 469 degrees of rotation> therefore, it
takes ?19 degrees to complete the four
stroke cycle.
#uring one piston stroke, the crankshaftrotates 879 degrees.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 17/44
4 STROKE DIESEL The operation of a d)e*e+ e!,)!e is comparable to a gasoline
engine.
They also have a number of components in common, /crankshaft,
pistons, valves, camshaft, and water and oil pumps.
(owever, diesel engines have op"e**)o! ignition systems. ;ather
than relying on a spark for ignition, a diesel engine uses the heatproduced by compressing air in the combustion chamber to ignite
the fuel.
The compression ratio of diesel engines is typically three times /as
high as 15:82 that of a gasoline engine.
As intake air is compressed, its temperature rises to ?99@$ to
99@$. Bust before the air is fully compressed, a fuel inector
sprays a small amount of diesel fuel into the cylinder. The high
temperature of the compressed air instantly ignites the fuel.
The combustion causes increased heat in the cylinder and the
resulting high pressure moves the piston down on its power stroke.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 18/44
4 STROKE DIESEL ENGINE
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 19/44
- STROKE ENGINE This engine re=uires only two strokes of the piston to
complete all four operations: intake, compression,
power, and exhaust.
This is accomplished as follows:
*ovement of the piston from %#$ to T#$ completes bothintake and compression.
"hen the piston nears T#$, the compressed air!fuel
mixture is ignited, causing an expansion of the gases.
#uring this time, the intake and exhaust ports are closed.
Expanding gases in the cylinder force the piston down,rotating the crankshaft.
"ith the piston at %#$, the intake and exhaust ports are
both open, allowing exhaust gases to leave the cylinder
and airfuel mixture to enter.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 20/44
- STROKE ENGINE
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 21/44
- STROKE ENGINE Although the twostrokecycle engine is
simple in design and lightweight because it
lacks a valve train, it has not been widely
used in automobiles. +t tends to be +e** ./e+ e..))e!t and releases
o"e po++/ta!t* into the atmosphere than
fourstroke engines.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 22/44
ROTARY0'ANKEL ENGINE The "ota" engine, or 'a!2e+ engine, is
similar to the standard piston engine in that
it is a spark ignition, internal combustion
engine. +ts design, however, is =uite different. or
one thing, the rotary engine uses a rotating
motion rather than a reciprocating motion.
+n addition, it uses ports rather than valvesfor controlling the intake of the airfuel
mixture and the exhaust of the combusted
charge.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 23/44
ROTARY0'ANKEL ENGINE
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 24/44
CHARACTERISTICS OF ROTARYENGINE The rotating combustion chamber engine is
small and light for the amount of power it
produces, which makes it attractive for use
in automobiles.
(owever, the rotary engine at present cannot
compete with a piston gasoline engine in
terms of durability, exhaust emissions, and
economy.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 25/44
BASIC ENGINE TERMINOLOGIES %ore C cylinder diameter measured in inches/in2 or
milimeters /mm2.
&troke C length of the piston travel between T#$
D %#$.
T#$ C Top dead center
%#$ C %ottom dead center
+f bore stroke, the engine is called a *3/a"ee!,)!e.
+f bore F stroke, the engine is called a oe"*3/a"ee!,)!e.
+f bore G stroke, the engine is called a
/!de"*3/a"e e!,)!e.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 26/44
$ylinder #isplacement C volume of the cylinder
when the piston is at %#$.
Engine displacement C sum!total of the
displacement of each of the engine cylidners.
Typically, an engine with a larger displacement
produces more tor=ue than a smaller
displacement engine.
$ompression ratio C comparison of a cylinder-s
volume when the piston is at %#$ to the
cylinder-s volume when the piston is at T#$.The higher the compression ratio, the more power
an engine theoretically can produce.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 27/44
ENGINE EFFICIENCY )olumetric efficiency describes the engine-s
ability to have its cylinders filled with air
fuel mixture.
+f the engine-s cylinders are able to be filledwith airfuel mixture during its intake stroke,
the engine has a volumetric efficiency of
899H.
Typically, engines have a volumetricefficiency of 79H to 899H.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 28/44
CYLINDER HEAD & 5AL5E TRAIN urpose of cylinder head
The cylinder head fits on top of the cylinder
block to close off and seal the top of the
cylinder.
The cylinder head also contains ports through
which the airfuel mixture enters and burned
gases exit the cylinder and the bore for the
sparkplug.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 29/44
TYPE OF 5AL5E TRAIN 'verhead )alve /'()2
'verhead $am /'($2
*ultivalve
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 30/44
O5ERHEAD 5AL5E #OH5$ The intake and exhaust valves in an '() engine
are mounted in the cylinder head and are operated
by a camshaft located in the cylinder block.
This arrangement re=uires the use of valve lifters,
pushrods, and rocker arms to transfer camshaftrotation to valve movement.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 31/44
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 32/44
O5ERHEAD CAM #OHC$ An '($ engine also has the intake and exhaust valves
located in the cylinder head.
%ut the cam is located in the cylinder head.
+n an '($ engine, the valves are operated directly by
the camshaft or through cam followers or tappets.
Engines with one camshaft above a cylinder are often
referred to as single overhead camshaft /&'($2
engines.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 33/44
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 34/44
MULTI5AL5E A multivalve design typically has three, four, or
five valves per cylinder to achieve improved
performance.
Any fourstroke internal combustion engine
needs at least two valves per cylinder: one for
intake of air and fuel, and another for exhaust
of combustion gases.
*ultivalve engines tend to have smaller valveshave lower reciprocating mass,
can reduce wear on each cam lobe,
more power from higher ;* without the danger of
valve bounce.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 35/44
MULTI5AL5E Threevalve cylinder head
This has a single large exhaust valve and two
smaller intake valves
ourvalve cylinder headThis is the most common type of multivalve
head, with two exhaust valves and two similar
/or slightly larger2 inlet valves.
ivevalve cylinder head<ess common is the fivevalve head, with two
exhaust valves and three inlet valves. All five
valves are similar in siIe.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 36/44
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 37/44
5AL5E TIMING "ith traditional fixed valve timing, an engine will have a period
of valve overlap at the end of the exhaust stroke, when both
the intake and exhaust valves are open.
The intake valve is opened %T#$ because to give enough time for
airfuel mixture to get into the cylinder.
The intake valve is allowed open A%#$ because to get advantagesof inertia created by velocity assists in drawing in the fresh
charge.
The exhaust valve is opened %%#$ because the gases inside the
cylinder posses a higher pressure even after the expansion
stroke. This higher pressure enables it to reduce the work that
needs to be done by the engine piston in pushing out these gases.
The exhaust valve close AT#$ because to give sufficient time for
exhaust gas exit through the exhaust valve. +f the exhaust valve
is closed like in actual timing diagram, a certain amount of
exhaust gases will get compressed and remain inside the cylinder
and will be carried to the next cycle also.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 38/44
5ARIABLES 5AL5E TIMING At low speed, a little valve lift already sufficient for
air!fuel to enter the cylinder.
The fuel consumption is better and enough for
cruising and low speed.
%ut at high speed, the valve need to open and closevery fast and need more longer time for air!fuel to
enter the cylinder.
Therefore, the valve lift must be higher and the
timing is longer.
+f the engine has fixed valve lift and valve timing, the
performance will be bad.
To increase the performance of the engine and better
fuel consumption, variable valve timing is introduced.
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 39/44
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 40/44
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 41/44
5IDEO (ow an Engine "orks $omprehensive Tutoria
l Animation featuring Toyota Engine Technol
ogies
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 42/44
E(ERCISE
8. Explain how 0stroke engine worksJ
1. $ompare 1stroke and 0stroke engines.
4. $ompare petrol and diesel engine.
0. &ketch and explain 0 process in the rotaryengine.
5. An engine has 0 cylinders. Each cylinder has
a bore of 5.85cm and its stroke is 6cm.
$alculate the engine displacements.6. #raw and explain a typical valve timing
diagram for 0stroke petrol engine.
?. "hat is Kvalve overlap-J
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 43/44
7UI8 1
$hapter 8
Buly 1984 /Tuesday2
7/21/2019 Engine components and classification
http://slidepdf.com/reader/full/engine-components-and-classification 44/44
THANK YOU