MECHANICAL POWER ENGINEERING DEPT.
FACULTY OF ENGINEERING - MANSOURA UNIVERSITY
FUNDAMENTALS OF
INTERNAL COMBUSTION
ENGINES
Dr. Waleed Shaaban
1
MECHANICAL POWER ENGINEERING DEPT.
FACULTY OF ENGINEERING - MANSOURA UNIVERSITY
COURSE CONTENTS
CHAPTER 1 INTRODUCTION
CHAPTER 2 OPERATING CHARACTERISTICS
CHAPTER 3 ENGINE CYCLES
CHAPTER 4 AIR AND FUEL INDUCTION
CHAPTER 5 COMBUSTION
CHAPTER 6 EXHAUST FLOW
CHAPTER 7 HEAT TRANSFER IN ENGINES
CHAPTER 8 FRICTION AND LUBRICATION
2
FUNDAMENTALS OF
INTERNAL COMBUSTION ENGINES
CHAPTER 1 INTRODUCTION
This chapter introduces and defines the internal
combustion engine. It lists ways of classifying
engines and terminology used in engine technology.
Descriptions are given of many common engine
components and of basic four-stroke and two-
stroke cycles for both spark ignition and
compression ignition engines.
3
FUNDAMENTALS OF
INTERNAL COMBUSTION ENGINES
CHAPTER 1 INTRODUCTION
1.1 Introduction
1.2 Early History
1.3 Engine Classifications
1.4 Terminology and Abbreviations
1.5 Engine Components
1.6 Basic Engine Cycles
1.7 Hybrid Vehicles
1.8 Fuel Cell Vehicles
1.9 Engine Emissions and Air Pollution
4
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.1 INTRODUCTION
The internal combustion (IC) engine is a heat engine that
converts chemical energy in a fuel into mechanical energy,
usually made available on a rotating output shaft.
5 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.2 EARLY HISTORY
The first fairly practical engine was invented by J.J.E. Lenoir (1822-1900)
and appeared on the scene about 1860.
In 1867 the Otto-Langen engine, with efficiency improved to about 11%, was
first introduced.
In the 1880s the internet combustion engine first appeared in automobiles.
By 1892, Rudolf Diesel (1858-1913) had perfected his compression ignition
engine into basically the same diesel engine know today.
Early compression ignition engines were noisy, large, slow, single-cylinder
engines. They were, however, generally more efficient than spark ignition
engines. It wasn't until the 1920s that multi-cylinder compression ignition
engines were made small enough to be used with automobiles and trucks.
6 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
Figure 1-1 The Charter Engine made in 1893 at Beloit works of
Fairbanks, Morse & Company was one of the first successful
gasoline engines offered for sale in the United States.
7 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
Figure 1-2 Cutaway view of Ford four-stroke cycle, spark-ignition, 6.0 liter V12
engine which was used in luxury/sport cars of mid 1990s. The engine was made
of aluminum alloy, with electronic fuel injection. Maximum brake power was 233
kW at 5350 RPM, with maximum torque of 478N.m at 3750 RPM.
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.3 ENGINE CLASSIFICATIONS
Internal Combustion Engines can be classified according to
1. Types of Ignition 2. Engine Cycle
3. Valve Location 4. Basic Design
5. Position and Number of Cylinders of Reciprocating Engines
6. Air Intake Process
7. Method of fuel Input for Spark Ignition Engines
8. Method of Fuel Input for Compression Ignition Engines
9. Fuel Used 10. Application
11. Type of Cooling
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.3 ENGINE CLASSIFICATIONS
1. Types of Ignition
a) Spark Ignition (SI): An SI engine starts the combustion process in each
cycle by use of a spark plug. The spark plug gives a high-voltage electrical
discharge between two electrodes which ignites the air-fuel mixture in the
combustion chamber surrounding the plug. In early engine development,
before the invention of the electric spark plug, many forms of torch holes
were used to initiate combustion from an external flame.
b) Compression Ignition (CI): The combustion process in a CI engine starts
when the air-fuel mixture self-ignites due to high temperature in the
combustion chamber caused by high compression.
10 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.3 ENGINE CLASSIFICATIONS
2. Engine Cycle
a) Four-stroke cycle: has four piston movements over two
engine revolution for each cycle.
b) Two-stroke cycle: has two piston movements over one
revolution for each cycle.
Three-stroke cycles and six-stroke cycles were also tried in early
engine development.
11 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
3. Valve Location
Valve in block Valve in head One valve in head Valves in block on
and one valve in opposite sides of
block cylinder
Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
(a) Valve in block, L head.
Order automobiles and some
on opposite sides of cylinder,
T head.
13
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
(b) Valve in head, I head.
Standard on modern
automobiles.
14
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
(c) One valve in head and one
valve in block, F head. Order,
less common automobiles.
15
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
(d) Valves in block on opposite
sides of cylinder, T head.
16
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.3 ENGINE CLASSIFICATIONS
4. Basic Design
a) Reciprocating: Engine has one or more cylinders in which pistons
reciprocate back and forth. The combustion chamber is located in the
closed end of each cylinder. Power is delivered to a rotating output
crankshaft by mechanical linkage with the pistons.
b) Rotary: Engine is made of a block (stator) built around a large non-
concentric rotor and crankshaft. The combustion chambers are built into
the non-rotating block.
17 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.3 ENGINE CLASSIFICATIONS
5. Position and Number of Cylinders of Reciprocating Engines
a) Single Cylinder. b) In-Line. c) V Engine.
18 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.3 ENGINE CLASSIFICATIONS
5. Position and Number of Cylinders of Reciprocating Engines
d) Opposed
e) W Engine
cylinder engine
f) Opposed
g) Radial Engine
Piston Engine
19 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.3 ENGINE CLASSIFICATIONS
6. Air Intake Process
a) Naturally Aspirated
b) Super charged
c)Turbocharged
d) Crankcase compressed
20 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.3 ENGINE CLASSIFICATIONS
7. Method of fuel Input for Spark Ignition Engines
a) Carbureted
b) Multipoint port Fuel Injection: One or more injectors at each
cylinder intake.
c) Throttle Body Fuel Injection: Injectors upstream in intake
manifold.
d) Gasoline Direct Injection: Injectors mounted in combustion
chambers with injection directly into cylinders.
21 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.3 ENGINE CLASSIFICATIONS
8. Method of Fuel Input for Compression Ignition Engines
a) Direct Injection: Fuel injected into main combustion chamber.
b) Indirect Injection: Fuel injected into secondary combustion
chamber
c) Homogeneous Charge Compression Ignition: Some fuel added
during intake stroke.
22 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.3 ENGINE CLASSIFICATIONS
9. Fuel Used
a) Gasoline
b) Diesel Oil or Fuel Oil
c) Gas, Natural Gas, Methane.
d) LPG.
e) Alcohol-Ethyl, Methyl.
f) Dual Fuel
g) Gasohol.
23 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.3 ENGINE CLASSIFICATIONS
10. Application
a) Automobile, Truck, Bus.
b) Locomotive.
c) Stationary.
d) Marine.
e) Aircraft.
f) Small Portable, Chain Saw, Model Airplane.
24 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.3 ENGINE CLASSIFICATIONS
11. Type of Cooling
a) Air Cooled.
b) Liquid Cooled, Water Cooled.
Several or all of these classifications can be used at the same time to
identify a given engine. Thus, a modern engine might be called a
turbocharged, reciprocating, spark ignition, four-stroke cycle,
overhead valve, water-cooled, gasoline, multipoint fuel-injected, V8
automobile engine.
25 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
Poppet valve is a spring loaded
closed, and pushed open by cam
action at proper time in cycle. Most
automobile engines and other
reciprocating engines use poppet
valves. Much less common are
sleeve valves and rotary valves.
Components include:
(A) valve seat, (E) spring,
(B) head, (F) camshaft,
(C) stem, (G) manifold.
(D) guide,
26 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.4 Terminology and Abbreviations
1. Internal Combustion (IC) 14. Smart Engine
2. Spark Ignition (SI) 15. Engine Management System (EMS)
3. Compression Ignition (CI) 16. Wide-Open Throttle (WOT).
4. Top-Dead-Center (TDC) 17. Ignition delay (ID)
5. Bottom-Dead-center (BDC) 18. Air-fuel Ratio (AF)
6. Direct Injection (DI) 19. Fuel-Air Ratio (FA)
7. Indirect Injection (IDI) 20. Brake Maximum Torque (BMT)
8. Bore 21. Overhead Valve (OHV)
9. Stroke Movement 22. Overhead Cam (OHC)
10. Clearance Volume 23. Fuel Injected (FI)
11. Displacement Volume
(swept volume.)
12. Gasoline Direct Injection (GDI)
13. Homogeneous Charge
27 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.5 Engine Components
Cross-section of four-stroke cycle SI
engine showing engine components:
(A) block,
(B) camshaft, (J) intake manifold,
(C) combustion chamber, (K) oil pan,
(D) connecting rod, (L) piston,
(E) crankcase, (M) piston rings,
(F) crankshaft, (N) push rod,
(G) cylinder, (O) spark plug,
(H) exhaust manifold, (P) valve,
(I) head, (Q) water jacket.
28
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.6 Basic Engine Cycles
FOUR-STROKE SI ENGINE CYCLE (c) Combustion at
almost constant
(a) Intake stroke (b) Compression stroke. volume near TDC.
29
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.6 Basic Engine Cycles
FOUR-STROKE SI ENGINE CYCLE
1. First Stroke: Intake Stroke or Induction
The piston travels from TDC to BDC with the
intake valve open and exhaust valve
closed. This creates an increasing volume
in the combustion chamber, which in turn
creates a vacuum. The resulting pressure
differential through the intake system from
atmospheric pressure on the outside to the
vacuum on the inside cases air to be
pushed into the cylinder. As the air passes
through the intake system, fuel is added to
it in the desired amount by means of fuel
injectors or a carburetor.
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.6 Basic Engine Cycles
2. Second stroke: Compression
Stroke
When the piston reaches BDC, the
intake valve closes and the piston
travels back to TDC with all the valves
closed. This compresses the air-fuel
mixture, raising both the pressure and
the temperature in the cylinder. The
finite time required to close the intake
valve means that actual compression
doesn't start until sometime aBDC. Near
the end of the compression stroke, the
spark plug is fired and combustion is
initiated.
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
•Combustion
Combustion of the air-fuel mixture occurs
in a very short but finite length of time with
the piston near TDC (nearly constant-
volume combustion) . It starts near the end
of the compression stroke slightly bTDC
and lasts into the power stroke slightly
aTDC.
3. Third Stroke: Expansion Stroke or
Power Stroke
With all valves closed, the high pressure
created by the combustion process pushes
the piston away from TDC. This is the
stroke which produce the work output of
the engine cycle. As the piston travels from
TDC, cylinder volume is increased, causing
pressure and temperature to drop.
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
•Exhaust Blowdown
Late in the power stroke, the exhaust valve is
opened and exhaust blowdown occurs. Pressure
and temperature in the cylinder are still high
relative to the surroundings at the point, and a
pressure differential is created through the
exhaust system which is open to atmospheric
pressure.
4. Fourth stroke: Exhaust Stroke
This pushes most of the remaining exhaust gases
out of cylinder into the exhaust system at about
atmospheric pressure, leaving only that trapped in
the clearance volume when the piston reaches
TDC. Near the end of the exhaust stroke bTDC,
the intake valve starts to open, so that it is fully
open by TDC when the new intake stroke starts
the next cycle. Near TDC the exhaust valve starts
to close and finally is fully closed sometime
aTDC.
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.6 Basic Engine Cycles
TWO-STROKE SI ENGINE CYCLE
1. First Stroke: Power or expansion
stroke
2. Exhaust blow-down
3. Intake and Scavenging when
intake port opens and air/fuel
mixture is forced into cylinder under
pressure. Intake mixture pushes
some of the remaining exhaust.
4. Second Stroke: Compression
stroke Spark ignition occurs near
end of compression stroke.
5. Combustion at almost constant
volume near TDC.
34 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.6 Basic Engine Cycles
TWO-STROKE CI ENGINE CYCLE
The two-stroke cycle for a CI engine is similar to that of the SI
engine except for two changes:
1. No fuel is added to the incoming air, so that compression is done on
air only.
2. Instead of a spark plug, a fuel injector is located in the cylinder.
Near the end of the compression stroke, fuel is injected into the hot
compressed is initiated by self-ignition.
35 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.7 Hybrid Vehicles
uses both an electric motor and an internal combustion engine to provide
power for propelling the vehicle. The goals of this type of vehicle are to
provide better fuel economy with fewer emissions.
Positive characteristics of a hybrid automobile:
1.Better fuel mileage. With a smaller engine operation at lean-burn
steady-state conditions, the engine can be optimized for minimum fuel
usage.
2.Combustion engines can be shut off when not, and the startup can be
very smooth with the help of the electric motor.
4. The electric drive motors can be built as dual motor-generator units.
This allows for some of the kinetic energy of the moving vehicle to be
recovered when the vehicle is slowed down or stopped.
36 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.7 Hybrid Vehicles
Negative characteristics of a hybrid automobile:
1. High cost at present.
2. Vehicles must carry dual weight of two power units, engine and
motor.
3. Any battery system will have a negative environmental impact
when the batteries are used up and discarded.
4. Air conditioning and other auxiliary power requirements are more
difficult to satisfy with an electrical system.
37 Back to chapter contents
38 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.8 Fuel Cell Vehicles
The use of fuel cells to supply power for propelling vehicles is attractive in that
it is a more efficient method of converting chemical energy of the fuel to useful
power output. It also produces far fewer harmful emissions than a combustion
engine, with water vapor being the major exhaust. Fuel cells generate
electricity by reversing the electrolysis process of water.
This can be done in one of several ways, a common type being a proton
exchange membrane cell (PEM). With this type of fuel cell, the unit is fueled
with hydrogen H2, and Oxygen O2 (air).
39 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.9 Engine Emissions and Air Pollution
Four major emissions produced by internal combustion engines are
1. hydrocarbons (HC), fuel and lubrication particles that did not get
burned and smaller non equilibrium particles of partially burned fuel.
2. carbon monoxide (CO), occurs when insufficient oxygen is present to
fully convert all carbon to CO2 or when incomplete air-fuel mixing
occurs due to the very short engine cycle tie.
3. oxides of nitrogen (NOx), are created in an engine when high
combustion temperature cases some normally stable N2 to
dissociate into monatomic nitrogen N, which then combines with
reacting oxygen.
4. solid particulates (part) solid carbon particles formed in compression
ignition engines and are seen as black smoke in the exhaust of these
engines other emissions found in the exhaust of engines include
aldehydes, sulfur, lead, etc.
40 Back to chapter contents
FUNDAMENTALS OF
CHAPTER 1 INTRODUCTION INTERNAL COMBUSTION ENGINES
1.9 Engine Emissions and Air Pollution
Two methods are used to reduce harmful engine
emissions:
1. improve the technology of engines and fuels so that
better combustion occurs and fewer emissions are
generated.
2. This is done by using thermal converters or catalytic
converters that promote chemical reactions in the
exhaust flow. These chemical reactions convert the
harmful emissions to acceptable CO2, H2O, and N2.
