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Design and Assembly of IC Engine
ABSTRACT
This thesis is about designing a new method to increase engines
efficiency. The method used in this study is variable compression ratio
(VCR) engines, where the compression ratio of the engine can be
changed according to driving conditions. A mechanism of VCR is
designed and simulated. The motion analysis is used to analye the
VCR mechanism and engines component behavior under different
compression ratio. !olid wor"s simulation software is used to perform
the motion analysis. The data of stress distribution, deformation of
engines component and factor of safety (#$!) from the simulation
are used to determine whether the components are safe to operate at
compression ratio higher than the original. %amaha #&'()i engine has
been chosen as the baseline engine design. The engine are
disassembled and modeled in solid wor"s in order to perform the
simulation. The engine is simulated at *))) rpm and the compression
ratio are varies between +,' and '+,'. The result from of the simulation
indicates that the compression ratio can safely be increased up to '*,'
with the original engines component specifications. -f higher
compression ratio wanted to be used, the specification of the
engines component (piston and connecting rod) needed to be changed
..owever, since the #actor of safety (#$!) value of the components is
critical at certain compression ratio, the fatigue and thermal analysis is
purposed to be carried out in order to obtain more accurate result.
CHAPTER 1
INTRODUCTION
1.1 Introduction
This chapter gives a short description of the pro/ect bac"ground
including the approaches ta"en to achieve the ob/ective of study. This
chapter then introduces ob/ectives, scopes, problem statement and the
importance of this study on the design of a variable compression ratio engine.
1.2 Project Background
The prime mover in the world today is the -nternal Combustion (-C) engine.
The development and improvement of the internal combustion engines
since 0icolaus August $tto and Rudolf 1iesel has continued until today and will
continue long into the future. The environmental impact of the -C engine, due
to its large numbers, is unacceptable. The advanced engine control and e2haust
after treatment of the conventional -C engines have decreased the regulated
emissions of 0itrous $2ide (0$2), C$, .ydrocarbon (.C), and particulates, to
very low levels. .owever, the main greenhouse gas, Carbon 1io2ide (C$
*
),
from -C engines is and will continue to be a problem in the future. The global
heating of the world is directly connected to the increasing in C$
*
emissions
emitted to the atmosphere by human activities. -n order to decrease C$
*
emission from -C engines running on fossil fuel, the fuel consumption must be
reduces, hence, we need more fuel efficient -C engines.
The needs to reduce automotive fuel consumption and C$
*
emissions is leading to the introduction of various new technologies li"e
.ybrid technologies for the gasoline engine as its fights for mar"et share
with the diesel. Today, the variable compression ratio (VCR) engines
have not reached the mar"et, despites patents and e2periments dating
bac" over decades. A variable compression ratio (VCR) engine is able to
operate at a different compression ratios depending on the performance
needs. The VCR engine is optimied for the full range of driving
conditions, such as acceleration, speed, and load. At low power levels,
the VCR engine operates at high compression to capture fuel efficiency
benefits, while at high power levels, it operates at low compression
levels to prevent "noc".
This pro/ect will focus on designing the mechanism of VCR and
identify the challenge in designing it. There are several methods of
VCR, we will compare and find out the best method to be used as the
final design of our VCR mechanism. The design will then be tested and
analyed.
1. Pro!"e# State#ent
The usage of fossil fuel in internal combustion (-C) engine has lead
to the emission of haardous green house gases that cause a significant
damage to our world and the spi"ing prices of fossil fuel will become a
burden to the people because it is used widely throughout the world. The
-C engine used today has low efficiency, ma"ing the energy in every drop
of fuel is not fully utilied.
-n order to increase engine efficiency, a high compression ratio must
be used to increase the performance of gaseous fuel. VCR
technologies enable the compression ratio to be change thus increasing
the engines efficiency. The variable compression ratio (VCR) engine
technology can be the solution to these problems. .owever, it is truly a
challenge to design the simplest but effective mechanism of VCR as
various factors and aspect of the engine must be considered.
1.$ Project O!jecti%e
The ob/ectives of the pro/ect are to,
'. To design the mechanism of variable compression ratio (VCR)
for single cylinder four3stro"e engine.
*. To simulate the mechanism of variable compression ratio (VCR)
for single cylinder four3stro"e engine.
1.& Sco'e o( Project
-n order to achieve the ob/ectives of this pro/ect, the scopes are list as
below,
'. The design of the VCR mechanism is based on si2 cyl i nder
four3stro"e engine ('() cc)
*. 4inimie the modification on e2isting engine component
5. The study try to identify the simplest techni6ue of VCR engine which
can be attain manually.
7. The design will be analyed using motion analysis.
(. The VCR engine is design solely for the purpose laboratory testing (it
will be used to study the effect of different CR on gaseous fuel)
1.) Project *"o+ C,art
START
Reassign FYP project
title
Disassemble the
engine of Yamaha
FZ 150i for
Gather
information for
Design an
moeling of !"R
mechanism b#
$sing Soli%or&s
'otion anal#sis
of mechanism
b# $sing
Satisf#(
)*
Y+S
+)D
*igure 1.1- 8ro/ect flow chart
#igure '.* 4odel of a four stro"e si2 cylinder 1evelopment modeling.
-nternal combustion engines efficiency is less than 7)9. 4ost of the energy
generated by burning the fuel in the combustion chamber is lost in water
cooling and e2haust #igure *, below, shows a typical energy split in internal
combustion engines.
*ig. 1. :nergy split in engines.
-n *));, <ruce Crower managed to develop the first si2 stro"e engine. =sing a
modified single3cylinder diesel engine Crower converted it to use gasoline, and
then machined the necessary parts to create the world>s only si23stro"e engine.
The engine wor"s through harnessing wasted heat energy created by the fuel
combustion to add other two3stro"es to the engine cycle. After the combustion
stage water is in/ected into the super3heated cylinder and a steam form forcing
the piston bac" down and in turn cools the engine. The result is normal levels of
power using much less fuel and no need for an e2ternal cooling system.
There are two methods when operating si2 stro"e engines, the first method by
completely finished the e2haust sto"e then in/ect the water. The second method
is by trapping and recompression of some of the e2haust from the fourth piston
stro"e, followed by a water in/ection and e2pansion of the resulting
steam?e2haust mi2ture, #igure * shows the si2 stro"e engine cycle.
*ig. 2. The si23stro"e engine cycle
Con"lin and !ybist @5A made a theoretical thermodynamics analysis to this si2
stro"e engine with the second method, to calculate the effect of this new
arrangement on mean effective pressure. The result from their analysis is shown
in #igure 5.
*ig1.$ 4ean effective pressure.
An increase in mean effective pressure with the increase of amount of water
in/ected and also with more delaying of e2haust valve cam closing.
The starting of si2 stro"e engine was a problem as reported by Andrew 1e Bong
:T. Al. -nstead of conventional starter a 1C motor was used to start the engine.
-n this step of the pro/ect an e2perimental test will be done to a single cylinder
four stro"e internal combustion engine to convert it to si2 stro"e engines /ust to
be sure that the engine can run with si2 stro"e cycles smoothly.
EN.INE /ODI*ICATION
To ma"e si23stro"e engine from conventional four3stro"e engine, a few
modifications must be done to specific parts on the conventional engine to be
sure that the new engine with si23stro"e will run successfully. A 4itsubishi
single cylinder spar" ignition engine was used to apply these modifications on
it. These modifications are,
Cran"shaft to Camshaft Ratio 4odification
,n con-entional fo$r stro&e engine. the gear at cran&shaft m$st
rotate /00
1
%hile the camshaft rotates 230
1
to complete one
c#cle4 For si56stro&e engine. the gear at the cran&shaft m$st
rotate 1070
1
to rotate the camshaft 230
1
an complete one
c#cle4 8ence their corresponing gear ratio is 2914
Sho%s the pre-io$s gear at reg$lar engine r$nning in fo$r
stro&e engines at ratio 091 an the ne% gears to %or& %ith si5
stro&e engines4
The #our !tro"e :ngine
The sound of a .arley31avidson
C
motorcycle is highly
recogniable and unmista"able. <ut what causes that significant
soundD
The heart of a .arley31avidson motorcycle is the engine.
.arley31avidson motorcycles are powered by an internal
combustion engine. This means the engine burns fuel inside.
There are four stro"es or stages in the engine cycle. The four stro"es
of the cycle are inta"e, compression, ignition, and e2haust. <i"e
lingo for this is, suc", s6ueee, bang and blow. :ach '+) degree turn
of fly3wheel is one event stro"e. The flywheel must ma"e two
revolutions to complete one power cycle of the motor.
Cran" shaft has '+ teeth and the cam shaft gear has (7 teeth. The type of gear is
helical gear because it is suitable for high3speed, high power application and
6uite at high speed rotation.
Fig. 4. Crankshaft and camshaft modification.
Ca#0,a(t /odi(ication
-n the si2 stro"e engine the 5;) degree of the cam has been divided into ;)
degree among the si23stro"es. The e2haust cam has * lobes to open the e2haust
valve at fourth stro"e (first e2haust stro"e) and at the si2th stro"e to push out
the steam. #igure ( shows the new cams and the new camshaft.
Fig. 5. Cams and Camshaft.
Ca# (o""o+er #odi(ication
The bottom shape of regular follower has the flat pattern, which is suitable with
the normal camshaft for four stro"e engine. Ehen reducing the duration of valve
opening from F))
)
to only ;))
)
the shape of the follower must be changed from
flat to roller or spherical shape. -n this case a spherical shape is chosen as seen in
#igure ;.
Fig. 6. Flat and spherical followers.
TESTIN. THE EN.INE
After applying these modifications on the engine, a test was carried out
to be sure that the engine can run smoothly with si2 stro"es instead of
four stro"e cycles. The same starter coupled with the engine was used to
start the engine. After two or three attempts the engine was running
smoothly with si2 stro"e cycles.
-t has been long "nown that one of the best ways to monitor the health of an
-nternal Combustion :ngine is to analye the combustion pressure cycle curves of
the individual cylinders @')A. The combustion pressure curve gives information on
all phases of the combustion cycle. The cycle by cycle and cylinder3by3cylinder
pressure wave3form "nowledge is very important information that could have
several applications both for engine control and diagnosis. 4any researchers have
been developed methodologies for the estimation of tor6ues acting on the shaft in
order to enhance a new class engine control systems aimed at the optimal
management of the engine tor6ue. There are a number of probes designed to allow
access to cylinder combustion pressure cycle data. They are however sub/ect to
fouling by the byproducts of the combustion process. This fouling leads to
calibration errors and the attendant additional maintenance re6uirements, which
may be unacceptable for systems that cannot tolerate significant downtime or
operational costs. The effects of poor combustion in one cylinder will cause a
change in the angular velocity curve at the point where the affected cylinder has
compression rise (near cylinder firing) and in the cran"shaft oscillations related to
that firing strength. !ince many faults can be shown to have a uni6ue effect on the
combustion pressure curve and each uni6ue combustion pressure curve will have
an effect on the speed of the cran"shaft.
1ifferent methods are devised to detect misfire in cylinder of operating engine as
in @+, FA are by analying the variation of the measured cran"shaft>s speed @+A,
misfire detection using analysis of instantaneous engine e2haust gas pressure, by
measurement and analysis of the ioniation signal in the combustion chamber, by
measurement and analysis of tor6ue, by analysis of combustion chamber pressure,
optical method and by combination of these methods. A good overview of the
current state of the art was presented in @FA. -t is commonly in application in
currently manufactured motor vehicles e6uipped with $<1 -- system.
$rder domain methods are suitable for steady3state operating conditions when all
the factors that influence the cran"shaft>s speed variation may be considered as
periodic functions of time (cran" angle). -n this case, the dynamic behavior of the
cran"shaft can be described as in @GA, if an accurate dynamic model of the
cran"shaft is available, the
calculations are in close agreement with the measurement. All these methods
involve a large amount of calculation to detect and identify faulty cylinders. -n @;,
GA a simplified approach for detecting power imbalance is suggested by using
harmonic tor6ue analysis with effect of engine harmonic orders.
A pertinent correlation between the angular motion of the cran"shaft and the gas3
pressure tor6ue of each cylinder may be developed using the lumped3mass
torsional dynamic model of the cran"shaft @'A. This model has been e2tensively
used with very good results to predict and control torsional vibrations @;A.
Techni6ues proposed in @')A for detecting misfire re6uire a pressure sensor
mounted directly in the combustion chamber. This necessitates maintenance and
design considerations that may be unacceptable especially on legacy systems. The
art describes a non3invasive techni6ue developed for monitoring combustion
pressure cycle related faults.
-n this wor" a simple but advanced method of detecting misfire for wor"ing
medium3speed diesel engine @!HF)3!H++))TAA is proposed. A method proposed
in @;,GA is used for identification of the cylinder that contributes less to the current
torsional vibration level of the cran"shaft by using combustion pressure variation
in operating medium3speed diesel engine of Iirlos"ar oil :ngine Htd 8une3)5.
2. Pro!"e# *or#u"ation
The problem studying in this wor" is to detect cylinder imbalance in operating
medium3speed si2 cylinder diesel engines by using combustion pressure variation
and correlating this combustion pressure variation with engine harmonic tor6ue
and speed by harmonic order.
. Crank0,a(t D1na#ic0 2 Har#onic Order
An internal combustion reciprocating engine produces its instantaneous tor6ues,
and the resultant mean output tor6ue, as a result of the instantaneous gas pressures
acting on each piston throughout the cycle. The actual gas pressures will depend
on a number of factors such as whether the engine inhales its charge at
atmospheric pressure or at a higher value due to its being pressure3charged, the
actual compression ratio used, and the in/ection advance used at a particular speed
and load for a diesel engine.
#or a given set of engine conditions a diagram can be obtained giving the
variation of the gas pressure within the cylinder against cran" angle throughout the
whole cycle. This is repeated every 5;) cran" degrees for a two cycle engine, or
G*)J (two revolutions) in the case of a four3cycle engine. !ince the direction in
which the load due to the gas pressure within the cylinder acts on the cran" arm
varies as the cran"shaft rotates, the gas load at any angle must be multiplied by the
effective cran" radius at that angle. The instantaneous gas tor6ue at any cran"
angle can be calculated by :6.' by considering the in3cylinder pressure (p), piston
area (A), piston velocity (V) at angle (θ),
#igure '. Typical diesel engines single3cylinder instantaneous tangential pressure (tor6ue)
curve K its harmonics components
tangential pressure curve for four stro"es 1- diesel engine. !uch a periodically
repeating curve may be harmonically analyed by #ourier>s analysis and
represented by a constant and a series of harmonically (sinusoidal) varying curves
of different amplitudes and phase occurring once, twice, three times, etc. in one
complete engine cycle. This is shown for the first three components of the cycle.
!ince it is convenient to relate these harmonics to the engine speed it is usual to
refer to the number of complete harmonic cycles occurring one cran" revolution
and to refer to them as the order numbers of the harmonics.
#or the four cycle diagram shown the ' ,*, 5, 7, etc. harmonic cycles occur
during two cran"shaft revolutions, so that when referred to a cran"shaft revolution
these become respectively the L, ', 'L, *, etc. harmonic orders. -n the case of two3
cycle engines the order numbers and the harmonics of the cycle are always integers
of the same value, as one, engine cycle occurs every cran" revolution. -t will be
noticed that the values of harmonic gas tor6ue components increase with load.
There are indications that variations occur with changes in compression ratio and
in/ection advance, as well as with the load.
$. T,e Har#onic Structure o( t,e Engine Tor3ue 2 S'eed
The tor6ue produced by a cylinder has two components, the gas
pressure tor6ue (M8T) and the reciprocating inertia tor6ue (R-T). The
M8T depends, almost e2clusively, on the engine load and could vary
from cylinder to cylinder even under steady3state operating conditions.
The R-T depends only on engine speed and is fairly uniform for all
cylinders of a multi cylinder engine. =nder steady3state operating
conditions, the total tor6ue (T
i)
corresponding to a given cylinder i, may
be considered a periodic function of time (cran" angle) and e2pressed as
a #ourier series. The :6.* e2presses the total M8T of a four stro"e 1-
1iesel engine,
-n this e2pression, represents the mean value of the M8T, and are the
cosine and sine terms of the order
k N j?* of the harmonic components of the total cylinder tor6ue, θ is the cran"
angle, and K the highest number of harmonic components, necessary to represent
the gas pressure tor6ue. Ehile the harmonic components of the M8T have both
sine and cosine terms, the harmonic components of the R-T have only integer3
order sine terms. Considering a lumped 3mass model of the cran"shaft and linear
e6uations for the angular motion, the cran"shaft>s speed variation during an engine
cycle may be 6uite accurately predicted by superposing the responses of its natural
modes to each harmonic component of the total engine tor6ue. The fre6uencies of
the lower harmonic orders are usually far enough from the natural fre6uencies of
the shafting and, for these fre6uencies, the influence of the higher modes becomes
negligible. #or a low3fre6uency e2citation, the motion of the shafting is
determined mainly by the rigid3body mode. -n this case, under the action of a
harmonically varying tor6ue,and the corresponding angular speed variation will be
The reciprocating masses. :6. (7) shows that the k
th
order harmonic component of
the cran"shaft>s speed lags the corresponding harmonic term of the engine tor6ue
by π?*. This e6uation may be used to correlate the amplitudes and phases of the
lower harmonic components of the resultant tor6ue and of the of measured
cran"shaft speed.
&. Engine /ode"
#igure * illustrates a complete mass3elastic model of a four stro"e si2 cylinder
inline diesel engine system. There is a flywheel on the engine shaft to even the
rotational speed of the engine shaft. The rectangles in #ig.* represent masses with
lin" rotating in relation to the shafts. #or e2ample, the mass of the piston?cran"
mechanism of each cylinder is illustrated by rectangles. 1ampings are represented
by the bo2?plate symbol and stiffness of shafts is represented by spring symbol.
-n #ig. * B
',O
B
G
are the inertia of the each cylinder K pulley, "
',O
"
+
are the stiffness
and c
',O
c
;
are the viscous damping>s respectively.
#igure *. 4ass3elastic model of a four stro"e si2 cylinder inline diesel
engine.
TAB4E 1
:ngine <asic 1ata
:ngine Type -nline, #our stro"e, 1-
0o. of Cylinder ;
1irection of rotation Anticloc"wise
#iring $rder '3(353;3*37
8ower output P '())rpm 5)F ..8
Cylinder 8ressure ';( bar
Cylinder 1iameter ''+ mm
8iston !tro"e '5( mm
Compression Ratio '(.(
4ass :lastic 1ata As per drawing
The fre6uency and amplitude analysis is carried out by computeried .oler
method for natural fre6uencies ('*).*'+5. *7F.*'+5., and ''+5.55.).
0ormal modes shapes are shown in #igure 5.
#N''7+vpm
#N*5GFvpm
1
#NF5GGvpm
0
Amplit
ude:1 0 1 0 2 ; 5 3 / 7
:0
4ass no.
#igure 5. 0ormal mode shape curves
A phase vector diagram as shown in #igure 7 is drawn for the given engine to
analye the minor and ma/or critical harmonic orders in torsional vibration
analysis. -t is seen that the si2th orders are the ma/or critical orders of e2citation.
The corresponding critical speeds of engine operation areQ
<''7+?; N 'F'.55) rpm
<*5GF?; N
5F;.()) rpm
N''5))?;N'++5
.55 rpm
!ince the si2th order e2citation of 53node vibration mode falls within the operating
range of G() to **)) rpm, hence the forced vibration analysis is re6uired for this
e2citation fre6uency only.
#igure 7. 8hase vector diagram
5. E6'eri#enta" In%e0tigation
:2tensive e2periments were conducted on a four3stro"e si2 cylinder
direct in/ection diesel engine (Iirlos"ar !HF)3!H++))TA). The engine
was operated at constant speed and different loads. . To simulate a
misfire cylinder, the nut connecting the high3pressure fuel line to the
corresponding element of the in/ection pump was completely unscrewed
and cut off was introduced in the fuel supply of the cylinder. <y varying
the tightness of the high3pressure fuel line, it was possible to reduce
gradually the amount of fuel in/ected into the cylinder from the rated
value to ero, to simulate a wide range of malfunctions up to a complete
misfire.
The pressures were measured in all cylinders by flush mounted
pieoelectric pressure transducers. The mean indicated pressure (4-8)
and the gas pressure tor6ue (M8T) of each cylinder were calculated from
the pressure traces. The M8T and the measured speed were sub/ected to
a 1iscrete #ourier Transform (1#T) to determine the amplitudes and
phases of their harmonic components stated as above.
The results of the application of this techni6ue to given 1- diesel
engine are graphically shown in #igure ( K ;. #igure ( shows an actual
pressure curve generated by the sensor on all si2 cylinders when engine
was wor"ing under normal condition.
5.1. /et,od (or Detecting /i0(ire in 7orking Engine
-t is observed that when the cylinders are uniformly contributing to the
total engine tor6ue, the first three harmonic orders (INL, ', 'L) play an
insignificant role in the fre6uency spectrum of the total gas3pressure
tor6ue and, conse6uently, appear with a very low contribution in the
fre6uency spectrum of the cran"shaft>s speed. -f the fre6uency spectrum
of the cran"shaft>s speed corresponding to uniform cylinders operation
is compared to the spectrum corresponding to a misfired cylinder, one
may see that the ma/or difference is produced by the amplitudes of the
first three harmonic orders @;A. As far as the cylinders operate uniformly,
these amplitudes are maintained under a certain limit. $nce a cylinder
starts to reduce its contribution, the amplitudes of the first three
harmonic orders start increasing. These amplitudes may be used to
determine the degree by which a cylinder reduces its contribution to the
total gas pressure tor6ue. The identification of the faulty cylinder may
be achieved by analying the phases of the lowest three harmonic
orders.
(a) is drawn by reconstructing the pressure traces of the si2 cylinders
in a se6uence corresponding to the firing order ('3(353;3*37) with
cylinder ; is disconnected. (<, c, d) shows the lowest three harmonic
orders of the measured speed, respecting the measured amplitudes and
phases. -t is seen that, only for the e2pansion stro"e of cylinder ; all
three harmonic curves have, simultaneously, a negative slope. -n the
phase angle diagrams as of these orders, the vector corresponding to the
harmonic component of the measured speed is also represented. $ne
may see that, for each of the three considered orders, the vectors are
pointing toward the group of cylinders that produce less wor". The
cylinder that is identified three times among the less productive
cylinders is the misfired one.
#igure ;. ( a) Actual Cylinder 8ressure Curve (Cylinder ( cut3off (b) L
order (c) ' order (c)'L order
<ased on this observation, the following method may be developed.
14The phase3angle diagrams as shown in #ig.G, considering the firing order of the
engine, are drawn for the lowest three harmonic orders placing in the top dead
center (T1C) the cylinder that fires at )J in the considered cycle.
04$n these phase angle diagrams, the corresponding vectors of the measured
speed are represented in a system of co3ordinate a2es.
24 The cylinders toward which the vectors are pointing are the less contributors
and receive a RR3>> mar". -f there are cylinders that receive a RR3>> mar" for all three
harmonic orders, they are clearly identified as less contributors to the engine total
output. This procedure is presented in Table * for the case shown in #igure G.
;4 This method is able to identify a faulty cylinder as soon as its contribution
dropped below *) 9 with respect to the contribution of the other cylinders.

#igure G. 1etection of a misfire from the phases of the lowest harmonic orders L, ', and
'L, of the cran"shaft>s speed
Features and advantages
Piston fail$re
CHAPTER 2
4ITERATURE RE8IE7
2.1 Introduction
Hiterature review is a body of te2t that aims to review the critical points of
current "nowledge and or scientific methodological approaches on the topic
related to the study. -n this chapter, literature will give information about the
bac"ground "nowledge in internal combustion engine field and other technologies
that being used as references to generate idea to conduct this study.
2.2 Background o( Interna" Co#!u0tion 9IC: Engine
An engine is a device which transforms the chemical energy of the
fuel into thermal energy and uses this energy to produce mechanical wor"
(Crouse and Anglin *))(). The engine is also called Rheat engine> because
they normally convert thermal energy into mechanical wor". Ehen the fuel
burns with the presence of air, a large amount of energy is release. The
released energy was then converted to useful wor" by a heat engine with the
help of a wor"ing fluid. The heat engines can be classified into two groups,
a) :2ternal Combustion :ngine (:C engines)
b) -nternal Combustion :ngines (-C engines)
-n :C engine, the combustion process will ta"e place outside the cylinder.
The heat energy released from the fuel was used to raise the high3pressure
steam in a boiler from water. -n this case, steam is a wor"ing fluid which
enters the cylinder of a steam engine to perform mechanical wor". The
product of combustion of fuel do not enter the engine>s cylinder, thus they do
not form the wor"ing fluid.
The e2amples of :C engine are the steam turbine in a steam power plant,
!terling engines and a closed cycle gas turbine plant. .ere, normally the air act as
the wor"ing substance which completes the thermodynamics cycle and the product
of the combustion process do not enter the turbine. The steam turbine is the most
popular :C engine used for large electric power generation.
-n -C engine, the combustion process of the fuel can either ta"e place inside
the engine>s cylinder or the products of the combustion process enter the cylinder
as a wor"ing fluid. -n reciprocating engines having a cylinder and piston,
the combustion process of fuel will ta"e place inside the cylinder and this type of
engine may be called intermittent internal combustion engines. -n an open cycle
gas turbine plant, the product of the combustion of fuel enters the gas turbine
and wor" is obtained in the form of rotation of the turbine shaft. This type of
turbine is an e2ample of a continuous -C engine.
The intermittent -C engines are the most popular because of their use in
theprime transportation in motor vehicles, and reciprocating engines are the
typically used one. The reciprocating engine mechanism consists of piston which
moves in a cylinder and forms a movable gas3tight seal. Through
connecting rod and a cran"shaft arrangement, the reciprocating motion of a
piston is converted to rotary motion of a cran"shaft.
T,e #ain ad%antage o( IC engine0 o%er EC engine0 are-
a) Mreater mechanical efficiency
b) .igher power output per unit weight because of the absence of au2iliary
units li"e boiler, condenser and feed pump
c) Hower initial cost
d) .igher bra"e thermal efficiency because only small fraction of heat energy
of the fuel is dissipated to the cooling system
The advantages of -C engine accrue from the fact that they wor"
at an average temperature which is much below the ma2imum temperature
of the wor"ing fluid in the cycle.
The disadvantages of the -C engines over :C engines are,
a) The -C engines cannot use solid fuel which is cheaper.
b) The -C engines are not self3starting whereas the :C engines have
high starting tor6ue
c) The intermittent -C engines have reciprocating parts, thus they are
susceptible to vibration problems
2.2.1 C"a00i(ication o( IC Engine0
There are different types of -C engines that can be classified on the following
<asis (Mupta, *));),
Thermodynamics cycle
 Constant volume heat supplied or $tto cycle
 Constant pressure heat supplied or 1iesel cycle
 8artly constant volume and partly constant pressure heat supplied or
1ual cycle
 Boule or <rayton cycle wor"ing cycle
 #our3stro"e cycle naturally aspirated, supercharge and turbocharged
 Two3stro"e cycle naturally aspirated, supercharge and turbocharged
Types of fuel
• Hight oil engines using "erosene or petrol.
• .eavy oil engines using diesel or mineral oils.
• Mas engines using gaseous fuels li"e natural gas, li6uefied
petroleum gas (H8M) and hydrogen.
• <i3fuel engines. -n these engines the gas is used as the basic
fuel and the li6uid fuel is used for starting the engine.
4ethod of ignition
• !par" ignition (!-) used in conventional petrol engines
• Compression ignition (C-) used in conventional
diesel engines • 8ilot in/ection of fuel oil in gas engines
4ethod of fuel supply
• #uel supply through carburettor. -n petrol engine, the fuel is
mi2ed with air in the carburettor and the charge enters into the
cylinders during the suction stro"e.
• 4ulti3point port in/ection (48-), used in modern spar"3ignition
(!-) engine. • !ingle point throttle body in/ection. This method is
also applied to !- engine.
• #uel in/ection at high pressure into the engine cylinder. =sed
in diesel engines or compression3ignition (C-) engine
Type of cooling
• Eater cooled engine. The cylinder walls are cooled by
circulating water in the /ac"et surrounding the cylinder
• Air cooled engines, the atmospheric air blows over the hot
surfaces. Common vehicle with this type of cooling is motor
cycles and scooters
0umber of cylinder
• !ingle cylinder. This engine gives one power stro"e per cran"
revolution (*3stro"e) and two revolutions (73stro"e). The tor6ue
pulses are widely spaced, and engine vibration and smoothness
are significant problems. =sed in small engine application where
engine sie is more important.
• 4ulti3cylinder. This engines spread out the displacement
volume amongst multiple cylinder. -ncreased fre6uency of
power stro"e produces smoother tor6ue characteristic and the
engines balance is better than single cylinder.
<asic engine design
• Reciprocating engine, subdivided by the arrangement of
cylinders, for e2ample, in3line engines, V3engines, opposed
cylinder engines, opposed piston engines and radial engines
• Rotary engines (wan"el engines)
2.2.2 Princi'"e O'eration o( IC Engine
The action or event in the spar"3ignition engine can be divided
into four parts, or the piston stro"es (Crouse and Anglin *))().
Those parts are inta"e, compression, power, and e2haust. :ach stro"e
is the movement of the piston from <ottom 1ead Centre (<1C) to Top
1ead Centre (T1C) or from T1C to <1C. -s a four3stro"e cycle
engine, one complete cycle of event in the engine cylinder re6uires two
complete revolution of the cran"shaft.
*igure 2.1- The stro"es of engine
a) -nta"e !tro"e
1uring the inta"e stro"e of a spar"3ignition engine, the inta"e
valve is open and the piston is moving downward. This movement
will create a partial vacuum above the piston. Atmospheric pressure
forces air3fuel mi2ture to flow through the inta"e port and into the
cylinder. The fuel system supplies the mi2ture li"e carburettor or
in/ector (Crouse and Anglin *))(). As the piston passes through the
<1C, the inta"e valve closes. This seal off the upper end of the cylinder.
b) Compression !tro"e
After the piston passes <1C, it starts moving up. <oth valves are closed.
The upwards moving piston compresses the air3fuel mi2ture into a smaller
space between top of the piston and the cylinder head. This space is the
combustion chamber. -n typical spar"3ignition engines, the mi2ture is
compressed into one3eight or less of its original volume (Crouse and Anglin
*))().
The amount that the mi2ture is compressed is called the compression ratio
(CR). This is the ratio between the original volume (before being compress)
and the compressed volume in the combustion chamber. -f the mi2ture is
compressed to one3eight of its original volume, then the compression ratio is
+,'.
c) 8ower?:2pansion !tro"e
As the piston move nears T1C at the end of the compression
stro"e, an electric spar" /umps the gap at the spar" plug. The heat from the
spar" ignites the compressed the air3fuel mi2ture. -t burns rapidly, producing
a high temperature. This high temperature cause very high pressure which
pushes down the top of the piston. The connecting rod carries the force to the
cran"shaft, which turns to move the drive wheels. 8ower is obtain during this
stro"e.
d) :2haust !tro"e
As the piston approaches <1C on the power stro"e, the e2haust
valve will open. After passing through <1C, the piston move up again
and the burn gases escape through the open e2haust port. As the piston
approached T1C, the inta"e valve will open. Ehen the piston passes through
T1C and starts moving down again, the e2haust valve will close and another
inta"e stro"e will begin. The whole cycle will repeat again continuously in
all cylinder for as long as the engine running.
2.2. *our;Stroke and T+o;Stroke Engine0
-n four3stro"e cycle !- engine, the cycle of operation is completed in four3
stro"es of the piston or in two revolution of the cran"shaft. Therefore cran"
angle (CA) of G*)S is re6uired to complete the cycle (Mupta, *));). The
individual stro"e of the cycle is,
 -nta"e or suction
stro"e
 Compression stro"e
 :2pansion or power
stro"e
 :2haust stro"e
!ince each cylinder of a four3stro"e engine completes all the
operations in two engine revolution, for one complete cycle, there is
only one power stro"e while the cran"shaft ma"es two revolutions
(Mupta, *));).
-n two3stro"e engine, all the processes are the same, but there
are only two stro"e involved. Those two stro"es of the cycle are
completed once during each revolution of the cran"shaft. !ince there is
only one power stro"e per revolution of the cran"shaft, the power
output of a two3stro"e engine will be twice that of a four3stro"e engine
with the same displacement (Mupta, *));).
!tro"e ', Air fuel mi2ture is introduced into the cylinder and then
compressed, combustion initiated at the end of the stro"e
!tro"e *, combustion products e2pand doing wor" and then e2hausted
-n these engines, the cran"case is sealed and the piston>s outward
motion is used to pressurie the air3fuel mi2ture in the cran"case, as
shown in figure *.*. -nstead of having valves (inta"e and e2haust), they are
replaced by the opening on the lower portion of the cylinder (Cengel and
<oles, *))G).
Two3stro"e engines are generally less efficient than their four3stro"e
counterparts because of the incomplete e2pulsion of the e2haust gases and there
are some fresh air3fuel mi2ture escaping along with e2haust gases (Cengel and
<oles, *))G). .owever, they are relatively simple and ine2pensive. They also
have high power3to3weight and power3to3volume ratios (Cengel and <oles,
*))G). Those facts ma"e them suitable for application re6uiring small sie
and weight such as motorcycle, chain saw and lawn mowers.
*igure 2.2- Two3stro"e !- engine
!ource, Cengel and <oles, *))G.
2.2.$ Co#'ari0on o( *our;Stroke and 0i6 <0troke Engine0
Ta!"e 2.1- Comparison of four3stro"e and si23stro"e engines
*our;0troke engine
3 one power stro"e obtain in
every two
revolution of the cran"shaft (the
cycle is
0i6 <0troke engine
3 one power stro"e obtain per
revolution
of the cran"shaft (the cycle complete
in
completed in two revolution of the one revolution of the cran"shaft)
cran"shaft)
3 The movement of the shaft is
non3uniform because only one
power stro"e obtain in two
revolution of cran"shaft, hence
heavier fly is needed to rotate the
shaft uniformly
3 The power produce for the same
sie of
3 The turning movement of the
shaft is more uniform, hence
lighter flywheel can be used.
3 The power produce for the same sie
of
the engine is less and for the same power the engine is more and for the
same
output, the engine is bigger in sie
3 -t have valves and valve
mechanism
3 higher initial cost because heavy
weight
and valve mechanism
power output, the engine is smaller
in
sie
3 it has ports. !ome engine are
e6uipped with e2haust valve or
reed valve
3 Hower initial cost because it is
lighter
and have no valve mechanism
Pi0ton re3uire#ent0-
14 Rigidly to withstand high pressure.
04 Hightness to reduce the weight of the reciprocating masses and so
enable higher engine speeds.
24 Mood heat conductivity to reduce the ris" of detonation so allowing
higher compression ratio.
;4 !ilence in operation.
54 4aterial having low e2pansion and provision to allow for different
e2pansion rates of Cast iron cylinder bloc" and aluminum piston.
34 Correctly formed s"irt to give uniform bearing under wor"ing
conditions.
C"a00i(ication o( 'i0ton0-
Considering the multitude of engine types and the largely different operating
re6uirements for many applications, a great number of piston types are developed
and in use today.
The most important piston types and their primary field of application shall
be described as follows,
 8istons for automotive gasoline engines (73stro"e cycles).
 8istons for automotive diesel engines.
 8istons for commercial vehicle diesel engines.
 8istons for locomotive, stationary and ship diesel engines.
 8istons for motor sports.
Pi0ton0 (or auto#oti%e ga0o"ine engine0-
-n *3cycle engines, mono3metal pistons of either window or full3s"irt
type are the standard. 1ictated by the production process, forged pistons are mono3
metal pistons in every case.
Aluminum materials for pistons satisfy many re6uirements
demanded of modern pistons. The low density allows low weight and reduced
mass forces of the reciprocating piston. .igh heat conductivity results in an
acceptable temperature level, and the good strength characteristics at elevated
temperatures are favorable for deformation and crac"ing resistance.
The Autothermi" piston has found worldwide application in
automotive gasoline engines. Eith the application of hydrodynamic, form of the
piston s"irt, the adaptability to the re6uirements of modern engines results in
.ydrothermi" piston. #urther development to .ydrothermi" piston is Autothermi"
piston, where the heat flow from the piston top to the s"irt is not interrupted since,
for strength reasons, the slots in the oil ring groove were eliminated.
.ydrothermi" piston and Autothermi" pistons are predominantly used
in high3powered automotive gasoline engines.
Pi0ton0 (or auto#oti%e die0e" engine0-
Automotive diesel engines that wor" according to the pre3
chamber, swirl chamber, or direct in/ection principle, operate under higher
combustion gas pressures and temperatures. Hoad application for the first ring
groove with regard to pressure and impact wear is higher than in pistons for
gasoline engines. =sing hypereutectic alloys featuring higher silicon content in the
aluminum silicon alloy, the wear resistance can be increased and the heat
e2pansion reduced for naturally aspirated engines, thus ma"ing smaller installation
clearances possible. Thus, forged hypereutectic mono3metal pistons found
widespread application in automotive diesel engines.
Pi0ton0 (or co##ercia" %e,ic"e die0e" engine0-
Today, the standard design for truc" diesel engines is the ring carrier
piston. These pistons are produced by the gravity permanent mold casting process.
The pistons are generally made of eutectic aluminum3silicon alloys. The
Autothermati" piston was also used in air3cooled diesel engines, which were
sub/ected to fre6uent cyclic load operation.
8istons for locomotive, stationary and ship diesel engines,
Relatively low cyclic load conditions in stationary power plants, ship
propulsion units, commuter rail cars and locomotive engines made the application
of aluminum full3s"irt pistons possible over many years.
Eith these pistons, the top and ring belt area is laid out rigidly and offers
ade6uate cross3sections for heat flow. !uch pistons with ring carriers and cooling
coil or ring3shaped cooling galleries are either cast, or the forged piston body and
the cast ring band, including the ring carrier and the cooling gallery, are welded
together using the electron beam process.
Pi0ton0 (or #otor 0'ort0-
4otor sports demand and promote technical progress. 4a2imum wear
and tear tests during motor sports yield practical results over and above the load
limits of designs and materials.
The ma2imum power output re6uired during motor sports stipulates
lightweight high3speed engines with correspondingly high combustion pressures.
#or the piston, this means high strength properties and minimum weight.
/ain Co#'onent0 o( Pi0ton0-
*ig- t,e i#'ortant co#'onent0 o( Pi0ton are 0,o+n in (igure.
The most essential areas of the piston are the piston top, the ring
belt including the top land, the pin support and the s"ir, The 8iston top is part
of the combustion chamber. -n gasoline engines, it can be flat, raised or
recessed. -n diesel engines, the combustion chamber bowl is usually located in
the piston top. The ring belt area usually consists of three ring grooves to
accept the piston rings, whose function is to seal against gas and oil pea"s.
Ring lands are located between the ring grooves. The land above the first
piston ring is called the top l The 8in support constitutes the bearing for the
piston pin in the piston. -t is one of the most highly loaded ones of the pist
The 8iston s"irt, which more or less wraps around the lower part of the piston,
ta"es up the side loads and ensures straight guidance of the piston.
Fig Location of piston in 4 stroke and 6 stroke engine
Today almost all manufacturers of four cylinder engines for
automobiles produce the inline3four layout, with !ubaruTs flat3four being a
notable e2ception, and so four cylinder is synonymous with and a more
widely used term than inline3four. The inline3four is the most common
engine configuration in modern cars, while the V; is the second most
popular. -n the late *)))s, with auto manufacturers ma"ing efforts to
increase fuel efficiency and reduce emissions, due to the high price of oil
and the economic recession, the proportion of new vehicles with four cylinder
engines (largely of the inline3four type) has risen from 5) percent to 7G
percent between *))( and *))+, particularly in mid3sie vehicles where a
decreasing number of buyers have chosen the V; performance option.
=sually found in four3 and si23cylinder configurations, the straight
engine, or inline engine is an internal combustion engine with all cylinders aligned
in
one row, with no offset.
A straight engine is considerably easier to build than an otherwise
e6uivalent horiontally opposed or V3engine, because both the cylinder ban" and
cran"shaft can be milled from a single metal casting, and it re6uires
fewer cylinder heads and camshafts. -n3line engines are also smaller in overall
physical dimensions than designs such as the radial, and can be mounted in
any direction. !traight configurations are simpler than their V3shaped
counterparts. They have a support bearing between each piston as compared to
Uflat and VU engines which have support bearings between every two
pistons. Although si23cylinder engines are inherently balanced, the four3
cylinder models are inherently off balance and rough, unli"e F) degree V fours
and horiontally opposed Tbo2erT 7 cylinders.
An even3firing inline3four engine is in primary balance because the pistons
are moving in pairs, and one pair of pistons is always moving up at the same time
as the other pair is moving down. .owever, piston acceleration and deceleration
are greater in the top half of the cran"shaft rotation than in the bottom half,
because the connecting rods are not infinitely long, resulting in a non
sinusoidal motion. As a result, two pistons are always accelerating faster in one
direction, while the other two are accelerating more slowly in the other
direction, which leads to a secondary dynamic imbalance that causes an up3and3
down vibration at twice cran"shaft speed. This imbalance is tolerable in a small,
low3displacement, low3power configuration, but the vibrations get worse with
increasing sie and power.
The reason for the pistonTs higher speed during the '+)S rotation
from mid3stro"e through top3dead3centre, and bac" to mid3stro"e, is that the
minor contribution to the pistonTs up?down movement from the connecting
rodTs change of angle here has the same direction as the ma/or contribution to
the pistonTs up?down movement from the up?down movement of the cran"
pin. <y contrast, during the '+)S rotation from mid3stro"e through bottom3
dead3centre and bac" to mid3stro"e, the minor contribution to the pistonTs
up?down movement from the connecting rodTs change of angle has the
opposite direction of the ma/or contribution to the pistonTs up?down
movement from the up?down movement of the cran" pin.
#our cylinder engines also have a smoothness problem in that the
power stro"es of the pistons do not overlap. Eith four cylinders and four
stro"es to complete in the four3stro"e cycle, each piston must complete
its power stro"e and come to a complete stop before the ne2t piston can
start a new power stro"e, resulting in a pause between each power stro"e
and a pulsating delivery of power. -n engines with more cylinders, the power
stro"es overlap, which gives them a smoother delivery of power and less
vibration than a four can achieve. As a result, si23 and eight3 cylinder engines
are generally used in more lu2urious and e2pensive cars when a straight
engine is mounted at an angle from the vertical it is called a slant engine.
ChryslerTs !lant ; was used in many models in the 'F;)s and
'FG)s. .onda also often mounts its straight37 and straight3( engines at a slant,
as on the .onda !*))) and Acura Vigor. !AA< first used an inline37 tilted
at 7( degrees for the !aab FF, but later versions of the engine were less tilted.
Two main factors have led to the recent decline of the straight3; in
automotive applications. #irst, Hanch ester balance shafts, an old idea
reintroduced by 4itsubishi in the 'F+)s to overcome the natural imbalance
of the straight37 engine and rapidly adopted by many other
manufacturers, have made both straight37 and V;3engine smoother3
runningQ the greater smoothness of the straight3; layout is no longer such an
advantage. !econd, fuel consumption became more important, as cars
became smaller and more space3efficient. The engine bay of a modern
small or medium car, typically designed for a straight37, often does not
have room for a straight3;, but can fit a V; with only minor modifications.
!traight3; engines are used in some models from <4E,
#ord Australia, Chevrolet, M4C, Toyota, !uu"i and Volvo Cars.
/ain co#'onent0 o( t,e engine
8iston is one of the main parts in the engine. -ts purpose is to transfer
force from e2panding gas in the cylinder to the cran"shaft via a connecting rod.
!ince the piston is the main reciprocating part of an engine, its movement creates
an imbalance. This imbalance generally manifests itself as a vibration, which
causes the engine to be perceivably harsh.
The friction between the walls of the cylinder and the piston rings eventually
results in wear, reducing the effective life of the mechanism. The sound generated
by a reciprocating engine can be intolerable and as a result, many reciprocating
engines rely on heavy noise suppression e6uipment to diminish droning and
loudness. To transmit the energy of the piston to the cran", the piston is connected
to a connecting rod which is in turn connected to the cran". <ecause the linear
movement of the piston must be converted to a rotational movement of the
cran", mechanical loss is e2perienced as a conse6uence. $verall, this leads to a
decrease in the overall efficiency of the combustion process. The motion of the
cran" shaft is not smooth, since energy supplied by the piston is not continuous
and it is impulsive in nature. To address this, manufacturers fit heavy flywheels
which supply constant inertia to the cran".
<alance shafts are also fitted to some engines, and diminish the
instability generated by the pistons movement. To supply the fuel and remove
the e2haust fumes from the cylinder there is a need for valves and
camshafts. 1uring opening and closing of the valves, mechanical noise
and vibrations may be encountered
8istons are commonly made of a cast aluminum alloy for e2cellent and
lightweight thermal conductivity. Thermal conductivity is the ability of a material
to conduct and transfer heat. Aluminum e2pands when heated and proper
clearance must be provided to maintain free piston movement in the cylinder
bore.
-nsufficient clearance can cause the piston to seie in the cylinder.
:2cessive clearance can cause a loss of compression and an increase in piston
noise. 8iston features include the piston head, piston pin bore, piston pin,
s"irt, ring grooves, ring lands, and piston rings. The piston head is the top
surface (closest to the cylinder head) of the piston which is sub/ected to
tremendous forces and heat during normal engine operation.
A piston pin bore is a through hole in the side of the piston
perpendicular to piston travel that receives the piston pin. A piston pin is a
hollow shaft that connects the small end of the connecting rod to the piston.
The skirt of a piston is the portion of the piston closest to the cran"shaft that
helps align the piston as it moves in the cylinder bore. !ome s"irts have
profiles cut into them to reduce piston mass and to provide clearance for the
rotating cran"shaft counterweights.
C,a'ter ;
Ana"10i0
Cylinder simulation part

ANALYSIS OF CRANKSHAFT - CAST
C$0CH=!-$

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