Automobile unit 2 Engine Auxiliary Systems

 Electronically controlled gasoline injection system for
SI engines.
 Electronically controlled diesel injection system ( Unit
injector system, Rotary distributor type and common
rail direct injection system)
 Electronic ignition system
 Turbo chargers
 Engine emission control by three way catalytic
converter system .

o The carburetor is a device used for atomizing and
vaporizing the fuel and mixing it with the air in
varying proportions to suit the changing operating
conditions of vehicle engines.
o The process of breaking up and mixing the fuel
with the air is called carburetion.

 It atomizes and vaporizes the fuel.
 It prepares the mixture of petrol and air in correct
proportions.
 It supplies a fine spray of petrol.
 It produces a homogenous mixture.

 Simple Carburetor
 S.U Carburetor – constant vaccum type
 Zenith Carburetor – compound jet with inner
main jet
 Solex Carburetor – Down draught type
 Carter Carburetor- Down draught type

 A modern gasoline injection system uses pressure from
an electric fuel pump to spray fuel into the engine intake
manifold.
 Like a carburetor, it must provide the engine with the
correct air-fuel mixture for specific operating
conditions.
 Unlike a carburetor, however ,PRESSURE, not engine
vacuum, is used to feed fuel into the engine .
This makes the gasoline injection
system very efficient

 Improved atomization. Fuel is forced into the intake
manifold under pressure that helps break fuel droplets into a
fine mist.
 Better fuel distribution. Equal flow of fuel
vapors into each cylinder.
 Smoother idle. Lean fuel mixture can be used without rough
idle because of better fuel distribution and low-
speed atomization.
 Lower emissions. Lean efficient air-fuel mixture reduces
exhaust pollution.

 Better cold weather drivability. Injection provides
better control of mixture enrichment than a carburetor.
 Increased engine power. Precise metering of fuel to
each cylinder and increased air flow can result in more
horsepower output.
 Fewer parts. Simpler, late model, electronic fuel
injection system have fewer parts than modern
computer-controlled carburetors.

 Indirect or direct injection
 Single- or multi-point injection

 An indirect injection system sprays fuel into the engine
intake manifold.
 Mostly gasoline injection systems are of this type.

 Direct injection forces fuel into the engine combustion
chamber.
 Diesel injection systems are of this type.

 Single-point injection is also called as Throttle Body
Injection (TBI).
 The point or location of fuel injection is one way to
classify a gasoline injection system.
 SPI or TBI has the injector nozzles in a throttle body
assembly on top of the engine.
 Fuel is sprayed into the top center of the intake manifold.

 Fuel tends to condense on the walls of the induction
manifold, subsequently evaporating off in an
uncontrolled manner.
 It is virtually impossible to obtain accurate
distribution of mixture equally to each cylinder.
 Hot spot must be provided in the throttle body to
facilitate evaporation and prevent icing.

 It is also called port injection
 It has an injector in the port (air-fuel passage) going to
each cylinder.
 Gasoline is sprayed into each intake port and toward
each intake valve.
 The term multipoint implies more than one location
fuel injection is used.

 In internal combustion engines, gasoline direct injection
is a variant of fuel injection employed in modern two-
and four- stroke petrol engines.
 The petrol/gasoline is highly pressurized, and injected
via a common rail fuel line directly into the combustion
chamber of each cylinder.
 When the driver turns the ignition key on, the power
train control module (PCM) energizes a relay that
supplies voltage to the fuel pump.
 The motor inside the pump starts to spin and runs for a
few seconds to build pressure in the fuel system.

 A timer in the PCM limits how long the pump will run
until the engine starts. Fuel is drawn into the pump
through an inlet tube and mesh filter sock.
 The fuel then flows to the fuel supply rail on the engine
and is routed to the individual fuel injectors.
 A fuel pressure regulator on the fuel rail maintains fuel
pressure, and recirculates excess fuel back to the tank.
 The fuel pump runs continuously once the engine starts,
and continues to run as long as the engine is running and
the ignition key is on.
 If the engine stalls, the (PCM) will detect the loss of the
RPM signal and turn the pump off.

SYSTEM COMPONENTS
 Fuel tank
 Electric fuel pump
 Fuel filter
 Electronic control unit
 Common rail and Pressure sensor
 Electronic Injectors
 Fuel line

 It is safe container for flammable liquids and typically
part of an engine system in which the fuel is stored
 Safe fuel storage.
 The fuel tank must be filled in a secure way and No
Sparks in the filling region.
 Storage of fuel (the system must contain a given
quantity of fuel and must avoid leakage and limit
evaporative emissions)
 Provide a method for determining level of fuel in tank
by Gauging

 Venting (if over-pressure is not allowed, the fuel
vapors must be managed through valves)
 Feeding of the engine through a pump

 An electric fuel pump is used with fuel injection to
pump fuel from the tank to the injectors.
 The pump must deliver the fuel under high pressure
(typically 30 to 85 psi depending on the application) so
the injectors can spray the fuel into the engine.
 Electric fuel pumps are usually mounted inside the fuel
tank,
 Some vehicles may even have two fuel pumps (a
transfer pump inside the tank, and a main fuel pump
outside).

 The fuel filter is the fuel system's primary line of
defense against dirt, debris and small particles of rust
that flake off the inside of the fuel tank .
 Many filters for fuel injected engines trap particles as
small as 10 to 40 microns in size.
 Fuel filter normally made into cartridges containing a
filter paper.

 In automotive electronics, electronic control unit (ECU)
is a generic term for any embedded system that controls
one or more of the electrical systems or subsystems in a
motor vehicle.
 An engine control unit (ECU), also known as power-train
control module (PCM), or engine control module (ECM)
 It is a type of electronic control unit that determines the
amount of fuel, ignition timing and other parameters an
internal combustion engine needs to keep running.
 It does this by reading values from multidimensional
maps which contain values calculated by sensor devices
monitoring the engine.

Control of fuel injection :
 If the throttle pedal is pressed further down, the ECU
will inject more fuel according to how much air is
passing into the engine.
 If the engine has not warmed up yet, more fuel will be
injected .
Control of ignition timing :
 An ECU can adjust the exact timing of the spark
(called ignition timing) to provide better power and
economy.

Control of idle speed :
The engine RPM is monitored by the crankshaft
position sensor which plays a primary role in the engine
timing functions for fuel injection, spark events, and
valve timing.
Idle speed is controlled by a programmable throttle
stop or an idle air bypass control stepper motor.

The term "common rail" refers to the fact that all of the
fuel injectors are supplied by a common fuel rail which is
nothing more than a pressure accumulator where the fuel is
stored at high pressure. This accumulator supplies multiple
fuel injectors with high pressure fuel.

 The injectors can survive the excessive temperature and
pressure of combustion by using the fuel that passes
through it as a coolant.
 The electronic fuel injector is normally closed, and opens
to inject pressurized fuel as long as electricity is applied to
the injector's solenoid coil.
 When the injector is turned on, it opens, spraying
atomized fuel at the combustion chamber .
 Depending on engine operating condition ,injection
quantity will vary .

 Fuel line hoses carry gasoline from the tank to the fuel
pump, to the fuel filter, and to the fuel injection system.
 While much of the fuel lines are rigid tube, sections of
it are made of rubber hose, which absorb engine and
road vibrations.
 There are two basic types of fuel hose: Fuel and oil
hoses that meet the SAE 30R7 standard, and fuel
injection hose that meets the requirements of SAE
30R9.

 The combustion of the fuel in CI engines begins in the
combustion chamber full of very hot air (more than
400ºC, often over 700 ºC).
 SI engine (petrol/gasoline) injection systems typically run
at pressure of 2 to 3 bar (30 to 40 psi).
 In contrast CI (diesel) engines employ injection pressures
of at least 350 bar (~5000 psi) and possibly in excess of
2000 bar (>29,000 psi)
 This explains why CI injection systems are so solidly built
and piped-up with strong steel tubing, etc.

Advantages
 Freedom from blow
backs and icing
 Better starting and
acceleration
 Increased volumetric
efficiency
 Increased power and
torque
Disadvantages
 Initial cost is very high
 More complicated
mechanism because of
electronic system,
injection nozzle and fuel
injection pump

 The fuel-injection system is the most vital component in
the working of CI engine.
 The engine performance, power o/p , economy etc is
greatly dependent on the effectiveness of the fuel-
injection system.
 In fuel-injection the fuel speed at the point of delivery is
greater than the air speed to atomize the fuel as in case
of S.I engines.

 Introduction of the fuel into the combustion chamber
should take place within a precisely defined period of
the cycle.
 The metering of amount of fuel injected per cycle
should done very accurately.
 The quantities of fuel metered should vary to meet the
changing load & speed requirements.
 The injection rate should be such that it results in the
desired heat-release pattern.

 The injected fuel must be broken into very fine
droplets.
 Proper spray pattern to ensure rapid mixing of fuel &
air.
 Beginning & end of injection should be sharp.
 Timing the injection of the fuel correctly in cycle so
that maximum power is obtained, ensuring economy &
clean burning.
 Uniform distribution of fuel droplets throughout the
combustion chamber.

Methods of fuel injection
 Indirect injection system
 Direct injection system
 Air injection system
 Air-less or solid injection system

 A direct injection diesel engine injects the fuel directly
into the combustion chamber. Many designs do not use a
glow plug.

 In an indirect injection (abbreviated IDI) diesel engine,
fuel is injected into a small prechamber, which is connected
to the cylinder by a narrow opening.
 The initial combustion takes place in this prechamber.
 This has the effect of slowing the rate of combustion, which
tends to reduce noise.

 In this method fuel is forced into the cylinder by
means of compressed air to a very high pressure. The
rate of fuel admission can be controlled by varying the
pressure of air .

ADVANTAGES:
 It provides better atomization & distribution of fuel.
 Heavy & viscous fuels, which are cheaper can also be
injected.
DISADVANTAGES:
 It requires a high pressure multi stage compression.
 A separate mechanical linkage is required to time the
operation of fuel valve.
 The fuel valve sealing requires considerable skill.
 Due to the compression & the linkage the bulk of the
engine increases .
 In case of sticking of the fuel valve , the system becomes
quite dangerous due to the presence of high pressure air.

In this method fuel is injected directly into the
combustion chamber without primary atomization is
termed as solid injection. it is also termed as mechanical
injection.
Solid injection system can be classified into four types:
 Unit injector system.
 Common rail system.
 Distributor system.
 Individual pump & injector.

 The unit injector system is one in which the pump &
injector are combined in one housing.
 Each cylinder is provided with one of these unit
injectors.
 Fuel is brought up to the injector by a low pressure pump
at proper time, a rocker arm actuates the plunger & thus
injects the fuel into the cylinder.

 In common rail system a high pressure fuel pump
delivers fuel to an accumulator, whose pressure is kept
constant with the help of a pressure regulating valve.
 A common rail or a pipe starts from the accumulator &
leads to the different distributing elements for each
cylinder.
 For each cylinder there is a separate metering & timing
element which is connected to an automatic injector
injecting fuel into the cylinder.
 In the common rail system the supply pressure of the
fuel is independent of speed & hence is not affected by
the fuel pump.
 The amount of fuel entering the cylinder is regulated by
varying the length of the push rod stroke.

Common Rail Diesel Injection system

 In this system the pump which pressurizes the fuel also
meters & times it .
 The fuel pump after metering the required amount of fuel
supplies it to rotating distributor at the correct time for
supply to each cylinder.
 The number of injection strokes per cycle for the pump
is equal to the number of cylinders.
 Since there is only one metering element , a uniform
distribution is automatically ensured .
 Not only that , the cost of the fuel injection system also
reduces to a valve less than two – third of that for
individual pump system.

Rotary distributor type Injection System

 In this system , each cylinder is provided with one pump
& one injector.
 Also in this system a separate metering & compression
pump is provided for each cylinder.
 The pump may be placed close to cylinder as shown in
below figure

 May be arranged in a cluster as shown in fig(b).
 In high pressure pump , plunger is actuated by a cam &
produces the fuel pressure necessary to open the
injector valve at the correct time .
 The amount of fuel injected depends on the effective
stroke of the plunger.

 Exhaust gas (or) oxygen sensor.
 Engine temperature sensor.
 Air flow sensor.
 Air inlet temperature sensor.
 Throttle position sensor.
 Manifold pressure sensor.
 Camshaft position sensor.
 Knock sensor.

 Nozzle is a part of an injector through which
the fuel is sprayed into the combustion
chamber.
Various types of nozzles used in C I engine are:
 Single hole nozzle.
 multi-hole nozzle.
 Pintle nozzle.
 Pintaux nozzle.

 Single hole nozzle are used in open combustion chamber. At the
center of the nozzle body there is a single hole which is closed by the
nozzle valve.
 The size of the hole is usually larger than 0.2mm.
 The hole may be drilled centrally or at an angle to the centre line of
the nozzle.
Main disadvantages of the Single hole nozzle are:
 Single hole nozzle has tendency to dribble.
 The spray angle is very narrow. This does not facilitate good mixing
unless higher air velocities are provided.

 In order to mix the fuel properly even with the slow air movement
available with many open combustion chamber ,a Multi-hole nozzle.
 The number of holes varies from 4 & 18 and the size from 1.5mm to
0.35mm.
 Advantages;
 Gives good atomization.
 Distribute fuel property even with lower air motion available in open
combustion chamber.
Disadvantages
 Dribbling b/w injection.
 Very high injection.
 Close tolerance in manufacture & hence costly.

 In order to avoid the weak injection & dribbling the spindle is provided with a
projection called pintle , which protrudes through the mouth of the nozzle body.
It either cylindrical or conical in shape.
 The size & shape of the pintle can be varied according to the requirement.
Advantages:
 Distribution & penetration poor. Hence not suitable for open combustion
chamber.
 It is self cleaning type.
 It prevent the carbon deposition on the nozzle hole.
 It result in good atomization.
 It avoid weak injection & dribbling.
 Disadvantages:

 It is a type of pintle nozzle which has an auxiliary hole drilled in the
nozzle body
 If the fuel is injected in a direction upstream the direction of air, the
delay period is reduced due to increased heat transfer b/w air & fuel.
This results in good cold starting performance.
Disadvantages:
 The tendency of the auxiliary hole to choke.
 The injection characteristics are even poorer then multi hole nozzle.

 Ignition system is the part of the electrical system which
carries the electrical current to the spark plug where the
spark is necessary to ignite the air fuel mixture in the
combustion chamber is produced.
 Coil ignition system or battery ignition system
 Magneto ignition system
 Electronic ignition system

 It is employed in petrol engine.
 It consists of a battery, ignition coil, condenser,
contact breaker, distributor and spark plugs.

 The initial cost is low.
 The maintenance cost is negligible expect battery.
 The weight is greater than magneto ignition
system.
 Wiring mechanism is more complicated.

 In this system, the battery is replaced with a magneto.
 It consists of a switch, magneto, contact breakers,
distributor, and spark plug.
 This system is used in two wheelers like motor cycles,
scooters etc.
 Less space is required.
 It is light in weight and compact in size.
 Initial cost is very high.
 Minimum 75 rpm is necessary to start the engine.

 There are some drawbacks in the magneto ignition system.
 Firstly, the contact breaker points will wear out or burn
when it is operated with heavy current.
 Secondly, the contact breakers is only a mechanical
device.
TYPES OF ELECTRONIC IGNITION SYSTEM
 Transistorized ignition system
➢ Pulse generator
➢ Hall effect Switch
➢ Piezo-electric
 Capacitance Discharge ignition system

 A transistor interrupts a relatively high current carrying
circuit.
 It controls a high current in the collector circuit with a
small current in base circuit.
 Therefore a transistor is used to assist the work of a
contact breakers.
 Hence this system is known as Transistor-assisted
ignition system

 No rotor, distributor cap, or spark plug cables
 Crankshaft position sensor: Determines engine speed and
crankshaft position
 Gives information for sequencing fuel injection system and
coil firing
 One coil for every two spark plugs
 One on the combustion chamber’s intake side
 The other is on the exhaust side
 Waste spark: Spark produced in one cylinder is used for
ignition and other spark is produced at the exhaust stroke of
another cylinder.
 Some engines have two spark plugs per cylinder

The following pollutants are emitted from
engines during combustion
 Carbon monoxide
 Oxides of nitrogen
 Hydrocarbons
 Photo chemical smog
 Smoke
 Lead
 Particulate
 Sulphur oxide

Global Atmospheric Concentration of CO2

 Late 1940’s – Air pollution(smog) - Los Angeles,
California and Increased further during 1950’s
 1960 emissison standards were enforced in california
 Later emission standards were followed in Japan and
Europe
 The emissions were reduced to about 90% during the year
1970 & 1980’s
 By 1990’s automobile engine were developed which
consumes less than half of the fuel used in 1970
 India follows Euro norms from 1999

Indian Emission Standards (4-Wheel Vehicles)
Standard Reference YEAR Region
India 2000 Euro 1 2000 Nationwide
Bharat Stage II Euro 2 2001 NCR*, Mumbai, Kolkata,
Chennai
2003.04 NCR*, 13 Cities†
2005.04 Nationwide
Bharat Stage III Euro 3 2005.04 NCR*, 13 Cities†
2010.04 Nationwide
Bharat Stage IV Euro 4 2010.04 NCR*, 13 Cities†
Bharat Stage V Euro 5 2019.04
Bharat Stage VI Euro 6 2020.04 (proposed) Entire country
* National Capital Region (Delhi)
† Mumbai, Kolkata, Chennai, Bengaluru, Hyderabad, Ahmedabad, Pune, Surat, Kanpur, Lucknow, Sholapur,
Jamshedpur and Agra

Indian Emission Standards (2 and 3 wheelers)
Standard Reference Date
Bharat Stage II Euro 2 1 April 2005
Bharat Stage III Euro 3 1 April 2010
Bharat Stage IV Euro 4 1 April 2012
Bharat Stage V Euro 5 1 April 2017 (proposed)
Progress of emission standards for 2-and 3-wheelers
Emission Standards for Diesel Truck and Bus Engines, g/kWh
Year Reference Test CO HC NOx PM
1992 – ECE R49 17.3–32.6 2.7–3.7 – –
1996 – ECE R49 11.20 2.40 14.4 –
2000 Euro I ECE R49 4.5 1.1 8.0 0.36*
2005† Euro II ECE R49 4.0 1.1 7.0 0.15
2010† Euro III
ESC 2.1 0.66 5.0 0.10
ETC 5.45 0.78 5.0 0.16
2010‡ Euro IV
ESC 1.5 0.46 3.5 0.02
ETC 4.0 0.55 3.5 0.03
* 0.612 for engines below 85 kW
Trucks and buses

Exhaust Emissions are produced by cars, buses, and
motorcycles.
Four basic types of exhaust emissions
 Hydrocarbons (HC)
 Carbon monoxides (CO)
 Oxides of nitrogen (NOx)
 Particulates.

 Resulting from the release of unburned fuel into the atmosphere
 Produced by incomplete combustion or by fuel evaporation
 Mostly related to ignition problems.
 Effect could be eye, throat, and lung irritation, and, possibly
cancer.
 Extremely toxic emission resulting from the release of partially
burned fuel (incomplete combustion of petroleum-based fuel).
 CO prevents human blood cells from carrying oxygen to body
tissue.
 Symptoms are headaches, nausea, blurred vision, and fatigue.
 A rich air-fuel would increase CO; lean air-fuel mixture would
lower CO emissions.

 Produced by extremely high temperatures during combustion.
 Air consist of about 79% nitrogen and 21% oxygen.
 With enough heat (above 2500ºF / 1370ºC), nitrogen and
oxygen in air-fuel mixture combines to form NOx emissions.
 An engine with high compression ratio, lean air-fuel mixture,
and high-temperature thermostat will produce high
combustion heat, resulting in formation of NOx.

1. Crankcase blow by
2. Evaporative emission
3. Exhaust emission
 Heating oil and burning of fuel that blows past piston
rings and into the crankcase.

 Chemicals that enter the air as fuel evaporate.
 Blown out of the tailpipe when engine burns a
hydrocarbon based fuel.

 Uses engine vacuum to draw blow-by gases into the
intake manifold for reburning in the combustion
chamber.
 Vacuum or electronic controlled, mounted on the valve
cover
•.

 At idle, high manifold vacuum pulls the plunger for
minimum vapour flow (prevents a lean air-fuel mixture).
 During acceleration, intake manifold decreases. This
allows the PCV valve to move to a center position for
maximum flow.
 With engine off, a spring pushes the valve against its seat,
closing the valve. A backfire will also close the valve.

 Allows burned gases to enter the engine intake manifold to
help reduce NOx
 When exhaust gases are added to air-fuel mixture, they
decrease peak combustion temperatures.
 Prevents toxic fuel system vapours from entering the
atmosphere.

Vacuum operated (Throttle Vacuum)
 When accelerated the throttle plate opens, engine vacuum
is applied to EGR, opening the diaphragm. Engine exhaust
can enter the intake manifold and combustion chamber.

Electronic-Vacuum EGR
 Valve uses both engine vacuum and electronic control
for better exhaust gas metering.

 Forces fresh air into the exhaust ports or catalytic
converter to reduce HC/CO.
 Oxygen from the air injection system causes the
unburned fuel to burn in the exhaust system or the
catalytic converter.

Parts of air injection system
 Air Injection Pump is belt driven and forces air at low
pressure into the system.
 Diverter Valve keeps air from entering the exhaust system
during deceleration. Air Distribution manifold is used to
direct a stream of air toward each engine exhaust valve.
 Air Check Valve keeps exhaust gases from entering the air
injection system.

 Oxidizes (burns) the remaining HC and CO emissions that pass
into the exhaust system.
 Extreme heat (1400°F/760°C) ignites these emissions and
change them into carbon dioxide (CO2) and water (H2O).
 Catalyst is a substance that speeds a chemical reaction without
itself being changed (coated with ceramic honey comb).
 Catalyst Substance: Platinum and Palladium treats HC and CO
emissions; Rhodium acts on the NOx emissions.

1. Mini Catalytic Converter is placed close to the engine
exhaust manifold.
2. Two-way Catalytic Converter can only reduce HC &
CO (Platinum).

3. Three-way Catalytic Converter reduces HC, CO & NOx
(Platinum and Rhodium).
4. Dual-bed Catalytic Converter normally has both a three-way
(reduction) and a two-way (oxidation) catalyst.
 Mixing chamber is provided between the two.
 Air is forced into the mixing chamber to help burn the HC
and CO emissions.

 Both turbochargers and superchargers are called forced
induction systems.
 They compress the air flowing into the engine. The advantage
of compressing the air is that it lets the engine stuff more air
into a cylinder.
 More air means that more fuel can be stuffed in, too, so you get
more power from each explosion in each cylinder.
 A turbo/supercharged engine produces more power overall than
the same engine without the charging.

 The typical boost provided by either a turbocharger or a
supercharger is 6 to 8 pounds per square inch (psi).
 Since normal atmospheric pressure is 14.7 psi at sea level, it is
able to provide 50-percent more air into the engine.
 Therefore, it is expected to get 50-percent more power. It's not
perfectly efficient, though, so you might get a 30-percent to 40-
percent improvement instead.

WHAT IS A SUPERCHARGER
 In basic concept, a supercharger is nothing more
than an air pump mechanically driven by the
engine itself.
 Usually compress the fuel/air mixture after it
leaves the carburetor.
 Some of the power created is offset by the power
required to drive the supercharger.

SUPERCHARGING OR TURBOCHARGING PRINCIPLES
 When air–fuel charge is ignited it produces
force which is directly a function of the charge
density.
 So here we increase the charge density by
using supercharger or turbocharger.
The more air and fuel that can be packed in a cylinder, the
greater the density of the air–fuel charge.

A part of the
exhaust gas
energy is treated
by the turbine
The turbine power
is transmitted to
the compressor
through the
rotating shaft
The air is
pressurized by the
compressor
The engine can
work at a high
power density
without increase
of the thermal
load
Turbocharging Principles
The air cooler
brings the air to a
high density to the
engine by
decreasing the
temperature

WHY WE USE ?
 It uses some of the unused energy contained in the hot
exhaust gases.
 Wide range of power levels.
 Increases the density of the air to add more fuel.
 Reduces specific fuel oil consumption.
 Improves mechanical, thermal efficiencies.

INTAKE AIR
CARBURETOR
EXHAUST
WHY TURBOCHARGERS ? NOT SUPRECHARGERS
 The turbocharger does not drain power from the engine.
 By connecting a turbocharger as much as 40% to 50% of waste
energy we can use.

FUEL/AIR
MIXTURE
EXHAUST
GASES
 Some of the power created is waste to drive the
Supercharger as it is driven directly from the
engine.

 Turbine.
 Air compressor.
 Shaft
 Waste gate
 Lube holes or groove
 Snap rings
 Thrust Bearing
 Heat Shield or The turbine back plate
 Compressor & Turbine Housing

WHAT IS A TURBOCHARGER ?
 Turbocharger or turbo is a turbine driven compressor.
 It uses the waste energy from exhaust gas to increase
the charge mass of air and power of the engine.
 A form of super charger, the turbocharger increases
the pressure of air entering the engine to create more
power.

The exhaust drives the turbine wheel on the left,
which is connected to the impeller wheel on the right
through a shaft. The bushings that support the shaft
are lubricated with engine oil under pressure.

 A turbocharger uses exhaust gases to increase boost, which
causes the engine to make more exhaust gases, which in turn
increases the boost from the turbocharger.
 To prevent overboost and severe engine damage, most
turbocharger systems use a wastegate.
 A wastegate is a valve similar to a door that can open and close.
 The wastegate is a bypass valve at the exhaust inlet to the
turbine.
 It allows all of the exhaust into the turbine, or it can route part
of the exhaust past the turbine to the exhaust system.

A wastegate is used in the diesel to control maximum boost pressure.

 Turbocharger response time is directly related to the size of the
turbine and compressor wheels.
 Small wheels accelerate rapidly; large wheels accelerate slowly.
 While small wheels would seem to have an advantage over
larger ones, they may not have enough airflow capacity for an
engine.
 To minimize turbo lag, the intake and exhaust breathing
capacities of an engine must be matched to the exhaust and
intake airflow capabilities of the turbocharger.

1. WASTE GATE TURBOCHARGER (WGT)
 Waste gate valve is installed to prevent turbo breakage from
excess intake pressure and exhaust pressure in high engine speed
 Boost pressure follows engine speed, and amount of stroke
follows pressure
 Spring is selected with suitable spring constant to operate
actuator with the above values
Merits of WGT:
Enhancing Power, Fuel Economy, Noise Reduction, Drivability,
Delivery of O2 to engine at high altitude, Clean Emission

2. VARIABLE GEOMETRY TURBOCHARGER (VGT)
 Low Speed Range
 Maximize exhaust flux by expending exhaust line
 Increase MAX Torque(5~15%)
 High Speed Range
 Maximize exhaust velocity energy by downsizing exhaust
line
 Increase MAX Power(10~15%)
Merits of VGT:
Enhancing Power of O2 to Engine at High Altitude,
Clean Emissions, Fuel Economy, Noise Reduction, Driveability

 Diesel Powered Cars.
 Gasoline Powered Cars.
 Motorcycles.
 Trucks.
 Aircraft.
 Marine Engine.

0%
50%
100%
150%
200%
250%
1996-2015
Years
Level
* in terms of compressor power at engine design point for given volume flow rate and pressure
ratio
Turbocharger Performance
Impact on Turbocharging high-speed engines

Automobile unit 2 Engine Auxiliary Systems

Automobile unit 2 Engine Auxiliary Systems

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