Automobile Classification and Components

An Automobile
• A wheeled vehicle which carries its own motor and runs
on land. A car is an automobile where as a trolley is not
• Run primarily on roads
• Transportation of people
• Mostly refers to cars
• 590 million passenger cars worldwide as of 2002
2

Brief History
• Karl Benz in 1885 – An automobile powered by gasoline engine
(Germany)
• Patented on January 29 – 1886 for this
First Automobile [1]Karl Benz [1]
3

Classification of Automobiles
1. Based on Purpose :
• Passenger vehicles: These vehicles carry passengers. e.g:
Buses, Cars, passenger trains.
• Goods vehicles: These vehicles carry goods from one place
to another place. e.g: Goods lorry, Goods carrier.
• Special Purpose: These vehicles include Ambulance, Fire
engines, Army Vehicles.
2. Based on Load Capacity:
• Light duty vehicle: Small motor vehicles. eg: Car, jeep,
Scooter, motorcycle
• Heavy duty vehicle: large and bulky motor vehicles.
e.g: Bus, Truck, Tractor

3. Based on fuel used:
• Petrol engine vehicles : Automobiles powered by a
petrol engine. e.g: scooters, cars, motorcycles.
• Diesel engine vehicles : Automobiles powered by
diesel engine. e.g: Trucks, Buses, Tractors.
• Gas vehicles : Vehicles that use gas turbine as a power
source. e.g: Turbine powered cars.
• Electric vehicles : Automobiles that use electricity as a
power source. e.g: Electric cars, electric buses.
• Steam Engine vehicles : Automobiles powered by
steam engine. e.g: Steamboat, steam locomotive, steam
wagon.

4. Based on Drive of the vehicles:
• Left-Hand drive : Steering wheel fitted on the
left-hand side.
• Right-Hand drive : Steering wheel fitted on
the right-hand side.
• Fluid drive : Vehicles employing torque
converter, fluid flywheel or hydramatic
transmission.

5. Based on number of wheels and axles:
• Two wheeler : motorcycles, scooters
• Three-wheelers : Tempo, auto-rickshaws
• Four wheeler : car, Jeep, Bus, truck
• Six-wheelers : Buses and trucks have
six tires out of which four are carried on the
rear wheels for additional reaction.
• Six axle wheeler : Dodge(10 tire) vehicle

6.Based on working cycle.
• Otto cycle engine.
• Diesel cycle engines.
7. Number of Strokes per cycle.
• Two stroke engines.
• Four stroke engines.
8. Based on cooling system.
• Air cooled engines
• Water cooled engines

9. Based on type of transmission:
• Automatic transmission vehicles: Automobiles that
are capable of changing gear ratios automatically as
they move. e.g: Automatic Transmission Cars.
• Manual transmission vehicles: Automobiles whose
gear ratios have to be changed manually.
• Semi-automatic transmission vehicles: Vehicles that
facilitate manual gear changing with a clutch pedal.
10. Based on Suspension system used:
• Convectional – Leaf Spring
• Independent – Coil spring, Torsion bar, Pneumatic.

Components of an automobile
1. Basic structure
• Frame
• Suspension system
• Axles
• Wheels
2. Power plant (Engine)
• I C engines
• Gas turbine
• Electric motors
3. The Transmission system
• Clutch
• Gear box
• Propeller shaft
• Differential

4. The Auxiliaries
• Supply system – Battery and generator
• The starter
• The ignition system – Battery and magneto
ignition
5. The controls
• Steering system
• Brakes
6. The superstructure
• The superstructure consists of the car body
attached to the frame.

Classification of automobile engines
 Cylinder arrangement
 Number of cylinders
 Cooling system type
 Valve location
 Camshaft location

 Combustion chamber design
 Type of fuel burned
 Type of ignition
 Number of strokes per cycle
 Number of valves per cylinder
 Type of aspiration

1 Cylinder Arrangement
 Refers to the position of the cylinders in relation to the
crankshaft
 There are five basic cylinder arrangements:
 inline
 V-type
 Slant
 W-type
 opposed

V engine Inline cylinder engines.

W engine
• A W engine is a type of reciprocating engine arranged
with its cylinders in a configuration in which the cylinder
banks resemble the letter W, in the same way those of
a V engine resemble the letter V.
• Three different configurations have been called W
engines:
• Three banks of cylinders sharing a common crankshaft, a
configuration also known as broad arrow configuration
• Four banks of cylinders sharing a common crankshaft,
also called a 'double-V'
• Two banks of cylinders with two crankshafts.

2. No: of Cylinder
 Most car and truck engines have either 4, 6, or
8 cylinders
 Some may have 3, 5, 10, 12, or 16 cylinders
 Engine power and smoothness are enhanced
by using more cylinders

3. Method of Cooling
 There are two types of cooling systems:
 Liquid cooling system
 surrounds the cylinder with coolant
 coolant carries combustion heat out of the cylinder head
and engine block
 Air cooling system
 circulates air over cooling fins on the cylinders
 air removes heat from the cylinders

4. Fuel Type
 Engines are classified by the type of fuel used
 Gasoline engines burn gasoline
 Diesel engines burn diesel fuel
 Liquefied petroleum gas (LPG), gasohol (10%
alcohol, 90% gasoline), and pure alcohol can
also be used to power an engine

5.Aspiration (how does air arrive)
• Normal aspiration – atmospheric pressure
• Forced induction (Turbo or Supercharger)

6. Method of Ignition
 Two basic methods are used to ignite the fuel
in an engine combustion chamber:
 spark ignition (spark plug)
 compression ignition (compressed air)

7. Valve Location
Engines are classified by the location of the valves:
1. L-head engine
 also called a flat head engine
 The suction and exhaust valves are arranged side by side in the
cylinder block.
2.F-head engine
 One valve is in the cylinder block and other valve is in cylinder
head.
3. I-head engine
 The suction and exhaust valves are arranged in the cylinder
head.

4. T- head engine
• The suction and exhaust valves are on the cylinder block in
opposite direction.

8.Camshaft Location
• There are two basic locations for the engine
camshaft:
1.Camshaft located in the block
• Uses push rods to transfer motion to the rocker
arms and valves
• Also called an overhead valve (OHV) engine

2.Camshaft located in the cylinder head
• overhead cam (OHC) engine
 OHC engines may use one or two camshafts
per cylinder head
1.Single overhead cam (SOHC) engine
• uses only one camshaft per cylinder head
2.Dual overhead cam (DOHC) engine
• uses two camshafts per cylinder head
• one cam operates the intake valves, while the
other cam operates the exhaust valves

Main parts of reciprocating engine
1. Cylinder Block
• Cylinder is the main body of IC engine. Cylinder
is a part in which the intake of fuel, compression
of fuel and burning of fuel take place.
• The main function of cylinder is to guide the
piston. It is in direct contact with the products of
combustion so it must be cooled. For cooling of
cylinder a water jacket or fin are situated at the
outer side of cylinder.
• At the upper end of cylinder, cylinder head and
at the bottom end crank case is bolted.

• The upper side of cylinder is consists of a combustion
chamber where fuel burns.
• To handle all this pressure and temperature generated
by combustion of fuel, cylinder material should have
high compressive strength. So it is made by high
grade cast iron. It is made by casting and usually cast
in one piece.

2. Cylinder head
• The top end of cylinder is closed by means of
removable cylinder head.
• There are two holes or ports at the cylinder
head, one for intake of fuel and other for
exhaust.
• Both the intake and exhaust ports are closed by
the two valves known as inlet and exhaust
valve.
• The inlet valve, exhaust valve, spark plug,
injector etc. are bolted on the cylinder head.

• The main function of cylinder head is to seal
the cylinder block and not to permit entry and
exit of gases on cover head valve engine.
• Cylinder head is usually made by cast iron or
aluminium.
• It is made by casting or forging and usually in
one piece.

3. Piston
• A piston is fitted to each cylinder as a face to receive gas
pressure and transmit the thrust to the connecting rod.
• It is the prime mover in the engine.
• The main function of piston is to give tight seal to the
cylinder through bore and slide freely inside of cylinder.
• Piston should be light and sufficient strong to handle the gas
pressure generated by combustion of fuel. So the piston is
made by aluminium alloy and sometimes it is made by cast
iron because light alloy piston expands more than cast iron
so they need more clearances to the bore.

4.Piston rings
• A piston must be a fairly loose fit in the cylinder
so it can move freely inside the cylinder.
• If the piston is too tight fit, it would expand as it
got hot and might stick tight in the cylinder and if
it is too loose it would leaks the vapour pressure.
• To provide a good sealing fit and less friction
resistance between the piston and cylinder,
pistons are equipped with piston rings.
• These rings are fitted in grooves which have been
cut in the piston. They are split at one end so they
can expand or slipped over the end of piston.

• A small two stroke engine has two piston rings to
provide good sealing but in a four stroke engine has
an extra ring which is known as oil ring.
• Piston rings are made of cast iron of fine grain and
high elastic material which is not affected by the
working heat.
• Sometimes it is made by alloy spring steel.

5. Connecting rod
• Connecting rod connects the piston to
crankshaft and transmits the motion and thrust
of piston to crankshaft.
• It converts the reciprocating motion of the
piston into rotary motion of crankshaft.
• There are two end of connecting rod one is
known as big end and other as small end.

• Big end is connected to the crankshaft and the
small end is connected to the piston by use of
piston pin.
• The connecting rods are made of nickel, chrome,
and chrome vanadium steels.
• For small engines the material may be aluminium.

6. Gudgeon pin or piston pin
• These are hardened steel parallel spindles
fitted through the piston bosses and the small
end bushes or eyes to allow the connecting
rods to swivel.
• It connects the piston to connecting rod.
• It is made hollow for lightness.

7. Crankshaft
• The crankshaft of an internal combustion
engine receives the efforts or thrust supplied
by piston to the connecting rod and converts
the reciprocating motion of piston into rotary
motion of crankshaft.
• The crankshaft mounts in bearing so it can
rotate freely.
• The shape and size of crankshaft depends on
the number and arrangement of cylinders

• It is usually made by steel forging, but some
makers use special types of cast-iron such as
spheroidal graphitic or nickel alloy castings
which are cheaper to produce and have good
service life.

8. Crankcase
• The main body of the engine to which the
cylinder are attached and which contains the
crankshaft and crankshaft bearing is called
crankcase.
• It serves as the lubricating system too and
sometime it is called oil sump.
• All the oil for lubrication is placed in it

9. Valves
• To control the inlet and exhaust of internal
combustion engine, valves are used.
• The number of valves in an engine depends on the
number of cylinders.
• Two valves are used for each cylinder one for inlet of
air-fuel mixture inside the cylinder and other for
exhaust of combustion gases.

10. Camshaft
• Camshaft is used in IC engine to control the opening and
closing of valves at proper timing.
• For proper engine output inlet valve should open at the
end of exhaust stroke and closed at the end of intake
stroke.
• So to regulate its timing, a cam is use which is oval in
shape and it exerts a pressure on the valve to open and
release to close.
• It is drive by the timing belt which drives by crankshaft.
It is placed at the top or at the bottom of cylinder.

1. Valve mechanism for operating the valve in engine
block or straight or side valve mechanism
• This mechanism is used in the engine block.
• It is mostly adopted in L,T and F type engine heads.
• The valve stem slides up and down in the valve
stem guide which acts as a slipper bearing.
• It also prevents the gases from passing from the valve
port to the valve chamber of the engine block.
• Valve spring is fitted between the engine block and
spring retainer, which keeps the valve closed tightly on
the valve seat, until lifted by the valve tappet by the
rotation of the cam.

• The tappet or lifter is held between guide which is
generally a part of the engine block.
• Adjusting screw is provided on the tappet to adjust the
clearance between the upper end of the tappet and the
bottom of the valve stem.
• As the cam rotates, it lifts the tappet which lifts the
valve to the open position thus connecting the valve
part to the combustion chamber.

2.Over head valve mechanism:
• It is used in I type and F type engine heads.
• This type valve operating mechanism requires a
push rod and a rocker arm.
• As the cam rotates, it lifts the valve tappet or the
lifter which actuates the push rod.
• The push rod rotates the rocker arm about a shaft-
the rocker arm shaft, or a ball joint in some
designs to cause one end to push down on the
valve stem to open the valve, thus connecting the
valve port with the combustion chamber.

• In this mechanism, the valve tappet clearance
is between the rocker arm and valve stem. It is
adjusted by means of an adjusting screw on the
rocker-arm end that contacts the push rod

Cooling system
• I.C Engines at best can transform about 25-30
% of the chemical energy from the fuel in to
mechanical energy.
• About 35 % of the heat generated is lost to
the cooling medium remainder being
dissipated through exhaust and lubricating oil.
• 1/3 Heat to Useful Work
• 1/3 Heat to cooling System
• 1/3 Heat to exhaust system

The Purpose of Cooling System
1.Prevent Overheating
• Excess Heat generated in engine
• Peak temperatures exceed melting point of
metal
2. Regulate the most efficient Temperature
• Regulate Temperature
• Allow engine to warm up in cool weather
• Maintain engine in optimum range.

Types of cooling System
There are two types of system in general
• Liquid or indirect cooling system
• Air or direct cooling system
1. Air or direct cooling system
• In an air cooled system a current of air is made to
blow past the outside of the cylinder barrel whose
outer surface area has been considerably
increased by providing cooling fins.
• This method will increase the rate of cooling

• This method is mainly applicable to engines in
motor cycles, small cars, airplanes and combat
tanks where the motion of vehicle gives
velocity to cool the engine

2. Water or indirect cooling system

Liquid Cooling System
• Mainly water/coolant water/coolant is used
and made to circulate through the jackets
provided around the cylinder, cylinder head,
valve ports and seats where it extracts most of
the heat.
• The heat transferred from the cylinder wall and
other parts by convection and conduction
• The heat from liquid in turn is transferred to
air.
• Hence it is called the indirect cooling system

Components
1. Water Jackets
• Defined as the open space within in the
cylinder block and cylinder head where
coolant flows .
• Water jackets are designed to allow coolant
flow to the right spots so that a maximum
cooling can be obtained

2. Water pump
• It purpose is to circulate the water through the
cooling system.
• Located on the front part of the engine.
• In most of the vehicles it is driven by a belt is
attached to the crankshaft.

3. Thermostat
• One of the most important parts of the cooling system.
• Its purpose is to keep the engine coolant at most
efficient temperature.
• The thermostat is used to bring the coolant temperature
up to operating as quickly as possible.
• It is designed to sense the temperature of the coolant
• Two types – 1. Bellows type
2. Pellet type

Wax pellet type thermostat
• The temperature sensitive material in the thermostat
is placed in a metal case and it expands when heated
and contracts when cooled.
• When the pellet is heated and it expands, the metal
case pushes down the valve and opens it.
• As the pellet is cooled, its contraction allows the
spring to close the valve.

4. Radiator
• Its purpose is to allow fresh air reduce the
temperature of the coolant.
• As the coolant passes through the tubes air is forced
around the tube.
• This causes a transfer of heat from the hot coolant to
the cooler air.
• In this case, heat is exchanged from the liquid coolant
to air.
• This is called a liquid-to air heat exchanger

5. Radiator cap
• As the engine’s coolant heats, it expands, increasing
pressure inside the closed coolant system.
• The radiator cap controls this expansion and provides a
constant pressure on the system.
• The caps pressure rating varies by engine application
anywhere from 13 – 16 psi.
• The radiator cap also allows the engine’s coolant to
expand and contract without all allowing air to enter the
cooling system.
• The upper seal seals and protects the system at all times.
• After the engine warms and system pressure reaches the
caps rated pressure, the pressure spring compresses and
pressurized coolant flows into the reservoir or coolant
overflow tank.
• This allows for expansion of the heated fluid.

• The cap also allows the coolant to flow back into the
radiator as the engine cools.
• The radiator cap also contains a vacuum valve. As
temperatures drop and the coolant contracts a vacuum
is created in the engine’s cooling system.
• The vacuum valve opens and allows coolant to flow
from the overflow tank back into the radiator.
• This allows for contraction as the fluid cools.

6. Expansion reservoir
• A radiator overflow tank collects the expanding coolant that is
heated by the engine and recycles it back into
the coolant system once it loses enough heat.
• The radiator overflow tank works in conjunction with the
radiator cap to protect the engine and prevent coolant loss due
to overflow.

8. Coolant
• Ethylene Glycol is the primary coolant utilized in
engines today.
• Typical mixtures are 50% water and 50% ethylene
glycol.
• Chemical inhibitors, that are alkaline, are added
to the coolant to eliminate acid formation.
• Ethylene glycol raises the boiling point and lower
the freezing point.
• Additives reduce cavitations – a major source of
cylinder wall pitting.
• Other additive inhibit rust and corrosion.

Valve timing
• Valve timing is the precise timing of the opening and closing of the valves.
• One way to look at this diagram is to think of these events in terms of the position
of the crankshaft and 360 degrees rotation.
• With 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 BTDC because to give enough time for air-fuel mixture
to get into the cylinder.
• The intake valve is allowed open ABDC because to get advantages of inertia
created by velocity assists in drawing in the fresh charge.
• The exhaust valve is opened BBDC 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 ATDC because to give sufficient time for exhaust gas exit
through the exhaust valve. If 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.

air cooling system
Advantages:
• It’s lighter in weight.
• Operated in extreme climates.
• Maintenance is easy.
 Disadvantages:
• Not easy to maintain
• Noise produce is high

5. Radiator pressure cap
• Water normally starts boiling at 100 deg C
• In order to increase the boiling temperature of water, the cooling
system is pressurized
• The radiator pressure cap is set at 1.9 bar so that the cooling
system operates under a pressure of 1.9 bar
• When the pressure exceeds 1.9 bar, the pressure valve opens
and lets out the excessive pressure along with some coolant
85

Purpose of Lubrication System
•Cleans
As it circulates through the engine, the oil picks up metal
particles and carbon, and brings them back down to the pan.

•Cools
Picks up heat when moving through the engine and then
drops into the cooler oil pan, giving up some of this heat.

•Absorbs shock
When heavy loads are imposed on the bearings, the oil
helps to cushion the load.
•Absorbs Contaminants
The additives in oil helps in absorbing the contaminants
that enter the lubrication system.

Need for Lubrication
• In an I.C. engine, moving parts rub against each
other causing frictional force. Due to the
frictional force, heat is generated and the engine
parts wear easily. Power is also lost due to
friction, since more power is required to drive an
engine having more friction between rubbing
surfaces.
• To reduce the power lost and also wear and tear
of the moving part substance called lubricant is
introduced between, the rubbing surfaces.

Functions of a Lubricant
• Lubricant reduces friction between moving part.
• It reduces wear and tear of the moving parts.
• It minimizes power loss due to friction.
• It provides cooling effect. While lubricating it also
carries some heat from the moving parts and
delivers it to the surroundings through the
bottom of the engine (crank case).
• It helps reduce noise created by the moving
parts.

Engine parts to be lubricated
• Crank shaft
• Crank pin
• Big and small end of the connecting rode
• Piston pin
• Internal surfaces of cylinder walls
• Piston rings
• Valve mechanisms
• Cam shaft etc.

Types of lubrication system
• Petrol lubrication system or Mist lubrication system.
• Wet sump lubrication system.
• Dry sump lubrication system.

Petrol Lubrication System
• This system of lubrication is used in scooters and
motor cycles.
• About 3% to 6% of lubricating oil is added with
petrol in the petrol tank.
• The petrol evaporates when the engine is
working. The lubricating oil is left behind in the
form of mist.
• The parts of the engine such as piston cylinder
walls, connecting rod are lubricated by being
wetted with the oil mist.

Fuel pump
• A fuel pump is a frequently (but not always)
essential component on a car or other internal
combustion engine.
• Carburetted engines use low pressure
mechanical pumps that are mounted outside
the fuel tank.
• Fuel injected engines often use electric fuel
pumps that are mounted inside the fuel tank.

Mechanical pump
• Most carburetted automobile engines used
mechanical fuel pumps to transfer fuel from the
fuel tank into the fuel bowls of the carburettor.
• Most mechanical fuel pumps are diaphragm
pumps, which are a type of positive displacement
pump.
• Diaphragm pumps contain a pump chamber
whose volume is increased or decreased by the
flexing of a flexible diaphragm, similar to the
action of a piston pump.
• A check valve is located at both the inlet and
outlet ports of the pump chamber to force the
fuel to flow in one direction only.

Carburettor
• Carburettor is a device that mixes air and fuel
for internal combustion engines in the proper
ratio for combustion.

Air
Filter
Tank
PETROL ENGINE – Carburettor Fuel System
Cockpit
Gauge
Pump
Carburettor
ExhaustInlet

Electronic petrol injection system

MPFI
• In petrol vehicles carburetor is used for supplying
air fuel mixture to the cylinder
• In response to the recent demand for cleaner
exhaust emission improved drivability and
mileage carburetor is not sufficient
• In place of the carburetor MPFI system is used in
vehicles
• MPFI system is injects fuel into individual
cylinders based on commands from engine
control module
• The MPFI gives higher output, faster throttle
response under varying driving conditions

Basic Concept
• MPFI is an intelligent way of doing what a
carburetor does.
• In this system each cylinder has injectors to
spray the fuel/air charge into the cylinders.
• The fuel and air are mixed in what is called the
intake manifold.
• In MPFI, each injector in controlled by the
ECU(Electronic Control Unit) or ECM (Engine
Control Module)

• The ECU monitors various engine parameters
and accordingly decides just how much fuel is
to be injected into the cylinder and at precisely
what time .
• This system also allows each cylinder to be
controlled independently

Catalytic converter
• A catalytic converter is an exhaust emission
control device that converts toxic gases
and pollutants in exhaust gas from an internal
combustion engine to less toxic pollutants
by catalyzing a redox reaction (an oxidation
and a reduction reaction).
• Catalytic converters are usually used
with internal combustion engines fuelled by
either petrol (gasoline) or diesel.

Gasoline direct injection (GDI)
• It also known as petrol direct injection, direct petrol
injection, spark-ignited direct injection (SIDI) and fuel-
stratified injection (FSI).
• It is a variant of fuel injection employed in modern two-
stroke and four-stroke gasoline engines.
• The gasoline is highly pressurized, and injected via
a common rail fuel line directly into the combustion
chamber of each cylinder, as opposed to
conventional multipoint fuel injection that injects fuel into
the intake tract or cylinder port.
• Directly injecting fuel into the combustion chamber requires
high-pressure injection, whereas low pressure is used
injecting into the intake tract or cylinder port.

• GDI (Gasoline Direct Injection) technology is
similar to CRDI (Common Rail Direct Injection).
• The only difference is that CRDI is for Diesel
Engines while GDI is for petrol engines.
• In both cases fuel is injected directly inside
combustion chamber and controlled by ECU
(Engine Control Unit).

Typical C.I. Fuel System Layout (Simplified)
Fuel Tank
Water
Trap
Lift Pump Fuel
Filters
Fuel
Injection
Pump
Fuel InjectorsLeak Off
Engine combustion
Chamber

Fuel Lift Pump (Low Pressure)
• Typically a diaphragm pump driven off
of the engine camshaft, or built into
the injection pump or electrically
driven in later systems
• May Have manual priming
• Function is to supply steady flow of
fuel to injection pump.
• May incorporate a strainer filter
which requires cleaning at service
intervals.

Main Fuel Filters• Maybe of replaceable element or
cartridge type.
• Filter material must be of large
enough surface area to allow for fuel
flow, which will stop very small
partials of dirt reaching the injection
system
• Maybe large single units or consist
of a ‘primary’ & ‘secondary’ filter.
• Must be changed at the correct
service interval
• Incorporate the water trap

High Pressure Fuel Injection Pumps
• Can be of ‘Rotary’ or ‘In line’
design. Driven by the engine at
half crankshaft speed
• Pressurises the fuel and delivers
it to the injections at the correct
time for combustion
• Accurately meters the fuel
quantity to match engine load
demands
• Incorporates a governor to
control engine speed and prevent
the engine over speeding and
damaging itself

Fuel Injectors
•Each injector is fitted in the
cylinder head above each
combustion chamber
•Fuel is delivered to the injectors via
thick walled high pressure steel pipes
Injector pipes are of equal
volume/length to ensure accuracy of
timing between cylinders
Each injector sprays atomized fuel in
to the combustion chamber to insure
complete combustion

Common Rail Injection
• A diesel fuel injection system employing a common pressure
accumulator, called the rail, which is mounted along the engine
block.
• The rail is fed by a high pressure fuel pump.
•The injectors, which are fed from the common rail, are
activated by solenoid valves.
•The solenoid valves and the fuel pump are electronically
controlled.
•In the common rail injection system the injection pressure is
independent from engine speed and load.
•Therefore, the injection parameters can be freely controlled.

Firing order
• The firing order is the sequence of power delivery of
each cylinder in a multi-cylinder reciprocating engine.
• This is achieved by sparking of the spark plugs in a
gasoline engine in the correct order, or by the sequence
of fuel injection in a Diesel engine.
• When designing an engine, choosing an appropriate
firing order is critical to minimizing vibration, to
improve engine balance and achieving smooth running,
for long engine fatigue life and user comfort, and
heavily influences crankshaft design.

Turbocharger
• A turbocharger, is a turbine-driven forced induction device that
increases an internal combustion engine's efficiency and power output
by forcing extra air into the combustion chamber.
• This improvement over a naturally aspirated engine's power output is
due to the fact that the compressor can force more air—and
proportionately more fuel—into the combustion chamber than
atmospheric pressure alone.
• Turbochargers were originally known as turbo superchargers when
all forced induction devices were classified as superchargers.
• Today the term "supercharger" is typically applied only to mechanically
driven forced induction devices.
• The key difference between a turbocharger and a
conventional supercharger is that a supercharger is mechanically driven
by the engine, often through a belt connected to the crankshaft.
• Whereas a turbocharger is powered by a turbine driven by the
engine's exhaust gas.
• Compared with a mechanically driven supercharger, turbochargers tend
to be more efficient, but less responsive.

Emission control system
• Emission control system, in automobiles, means employed to limit the
discharge of noxious gases from the internal-combustion engine and other
components.
• There are three main sources of these gases: the engine exhaust, the
crankcase, and the fuel tank and carburettor.
• The exhaust pipe discharges burned and unburned hydrocarbons, carbon
monoxide, oxides of nitrogen and sulphur, and traces of various acids, alcohols,
and phenols .
• The crankcase is a secondary source of unburned hydrocarbons and, to a lesser
extent, carbon monoxide.
• In the fuel tank and the carburettor, hydrocarbons that are continually
evaporating from gasoline constitute a minor but not insignificant contributing
factor in pollution.

• A variety of systems for controlling emissions from
all these sources have been developed.
1. In the crankcase—the portion of the engine block
below the cylinders where the crankshaft is
located—leaked combustion gases are combined
with ventilating air and returned to the intake
manifold for re burning in the combustion chamber.
The device that performs this function is known as
the positive crankcase ventilation valve, or PCV
valve.

2. To control exhaust emissions, which are
responsible for two-thirds of the total engine
pollutants, two types of systems are used:
the air-injection system and the exhaust gas
recirculation (EGR) system.
In EGR a certain portion of exhaust gases are
directed back to the cylinder head, where they
are combined with the fuel-air mixture and
enter the combustion chamber.

• In a typical air-injection system, an engine-
driven pump injects air into the exhaust
manifold, where the air combines with
unburned hydrocarbons and carbon monoxide
at a high temperature and, in effect, continues
the combustion process. In this way a large
percentage of the pollutants that were
formerly discharged through the exhaust
system are burned.
• Catalytic converter

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