KOLEJ VOKASIONAL MIRILORONG 10, JALAN JEE FOH, KROKOP

98000 MIRI, SARAWAK.

KERTAS PENERANGAN

PROGRAM TEKNOLOGI AUTOMOTIF

KOD MODUL MAT 503

TAJUK MODUL AIR INDUCTION AND EXHAUST SYSTEM

TAHUN / SEMESTER TAHUN 1 SEMESTER 5 DIPLOMA VOKASIONAL MALAYSIA

JAM KREDIT 3.0

JUMLAH JAM

KELAS/KULIAH

5.0 JAM / SEMINGGU

KOMPETENSI 1. CARRY OUT EMISSION CONTROL SYSTEM2. CARRY OUT INTERCOOLER UNIT REPLACEMENT3. CARRY OUT CATALYTIC CONVERTER REPLACEMENT4. CARRY OUT TURBOCHARGER RECTIFICATION WORK5. CARRY OUT SUPERCHARGER REPLACEMENT

STANDARD

PEMBELAJARAN

1.1 IDENTIFY EMISSION CONTROL SYSTEM1.2 IDENTIFY INTERCOOLER UNIT LOCATION1.3 IDENTIFY VEHICLE’S CATALYTIC CONVERTER

LOCATION1.4 IDENTIFY TURBOCHARGER LOCATION1.5 IDENTIFY SUPERCHARGER UNIT LOCATION

NAMA PELAJAR: TARIKH:

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TAJUK : AIR INDUCTION AND EXHAUST SYSTEM

OBJEKTIF :

Selepas aktiviti ini pelajar-pelajar mesti boleh :

1. Identify intercooler unit location

2. Identify intercooler unit location

3. Identify emission control system

4. Identify turbocharger location

5. Identify supercharger unit location

1.0 EMISSION CONTROL SYSTEM

1.1 INTRODUCTION

The emission control systems are installed to reduce the amount of CO, HC and NOx

exhausted from the engine ((3) and (4)), to prevent the atmospheric release of blow-by gas-

containing HC (1) and evaporated fuel containing HC being released from the fuel tank (2). The

function of each system is shown in these tables.

SYSTEM ABBREVIATIO

N

FUNCTION

Positive Crankcase Ventilation PVC Reduces HC

Three-Way Catalytic Converter TWC Reduces HC, CO and NOx

Electronic Fuel injection fuel for reduced EFI Injects a precisely timed,

optimum amount of exhaust

emission

Evaporative Emission Control EVAP Reduces evaporated HC

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Table 1

Picture 1

1.2 TYPES OF POLLUTIONS

1.2.1 SMOG

Smog is a term for the brownish-yellow haze that hangs in the warm, still air. It is

produced from industrial pollutants and automobiles. Hydrocarbon (HC), Nitrogen Oxide (NOx)

and volatile organic compounds (VOCs) are the pollutants that produce smog.

1.2.2 HYDROCARBON (HC)

It is another type of pollution produced by automobile combination process. Fossil fuels

are made of various hydrogen and carbon molecules. Unburned hydrocarbons emitted by the

automobile are largely unburned fuel. Any fuel that is partially burned contains hydrocarbons

and this is one of the main ingredients in the production of smog.

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1.2.3 CARBON MONOXIDE (CO)

Carbon Monoxide is considered a deadly poisonous gas that is colourless and

odourless. It causes headaches and vision difficulties if a person inhales small quantities. But in

larger quantities, it may cause sleepiness and death. Carbon Monoxide emissions are increased

as the combustion process becomes less efficient. It forms in the engine exhaust when there is

insufficient oxygen to form the carbon dioxide.

1.2.4 NITROGEN OXIDE (NOX)

Nitrogen Oxide is form freely under extreme heat condition. As the combustion process

becomes leaner, combustion temperatures typically increase. Higher temperature causes

nitrogen oxides to be produced. When the combustion temperatures reach 2,200 to 2,500

degrees Fahrenheit, the nitrogen and oxygen in the air-fuel mixture combine to form large

quantities of nitrogen oxide.

1.3 TYPES OF EMISSION CONTROL SYSTEM

i. Evaporative (EVAP) Control Systemii. Positive Crankcase Ventilation (PCV) Systemiii. Exhaust Gas Recirculation System (EGR)

1.4 EVAPORATIVE (EVAP) CONTROL SYSTEM

The evaporative emission control system prevents fuel vapors from escaping into

atmosphere. This system includes a canister, purge control solenoid valve, fuel cut valve, and the

lines connecting them. Fuel vapors in the fuel tank are introduced into the canister through the

evaporation line, and are absorbed by activated carbon in it. The fuel cut valve is also

incorporated in the fuel tank line. The purge control solenoid valve is controlled optimally by the

ECM according to the engine condition. The pressure control solenoid valve incorporated in the

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fuel tank evaporation line regulates the pressure/vacuum in the fuel tank under the control of the

ECM which uses the signal from the fuel tank pressure sensor. The diagnosis of the evaporative

emission control system is performed by turning each solenoid valve ON/OFF to vary the pressure

inside the fuel tank and measure this pressure change with the fuel tank pressure sensor in order to

check for leaks and proper valve operation.

Picture 2

1.4.1 FUEL CUT VALVE

The fuel cut valve is built onto the evaporation pipe of the fuel tank. The rising level of the

fuel in the fuel tank causes the float to move up and close the cap hole so that no fuel can flow to

the evaporation line.

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Picture 3

1.4.2 FUEL TANK CAP

The fuel tank cap has a relief valve which prevents development of vacuum in the fuel

tank in the event of a problem with the fuel vapor line. When there is no problem with the fuel

vapor line, the filler pipe is sealed at the portion (A) and by the seal pressed against the filler pipe

end. If vacuum develops in the fuel tank, the atmospheric pressure forces the spring down to open

the valve; consequently outside air flows into the fuel tank, thus controlling the inside pressure.

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Picture 4

1.4.3 CANISTER

The charcoal filled in the canister temporarily stores fuel vapors. When the purge control

solenoid valve is opened by a signal from the ECM, the external fresh air entering the canister

carries the fuel vapors into the intake manifold.

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Picture 5

1.3.4 PURGE CONTROL SOLENOID VALVE

The purge control solenoid valve is on the evaporation line between the canister and intake

manifold. The valve is installed under the intake manifold.

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Picture 6

1.4.5 PRESSURE CONTROL SOLENOID VALVE

The fuel tank pressure control solenoid valve is located in the evaporation line between the

canister and the fuel tank. When the tank inside pressure becomes higher than the atmospheric

pressure, the valve is opened allowing fuel vapors to be introduced into the canister. On the other

hand, when the tank inside pressure becomes lower than the atmospheric pressure, external air is

taken from the drain valve into the canister. The pressure control solenoid valve can also be

electrically closed for diagnosis of the evaporative emission control system.

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Picture 7

1.4.6 DRAIN FILTER

The drain filter is installed at the air inlet port of the drain valve. It cleans the air taken in the

canister through the drain valve.

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Picture 8

1.4.7 VENT VALVE

The vent valve is located in the fuel tank. During filling the fuel tank, fuel vapors are

introduced into the canister through the vent valve. When the fuel vapor pressure becomes higher

than the atmospheric pressure and overcomes the spring force which is applied to the back side

of the diaphragm, the port toward the canister is opened. The vent valve also has a float which

rises and blocks the port toward the canister when the fuel is full.

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Picture 9

1.5 POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM

During normal engine operation, a considerable amount of dirty air passes through the

engine crankcase. This air is the result of a process called blow-by. Blow-by is a product of

the combustion process which produces a small crankcase pressure. The gases from blow-by

are very acidic and will erode the lubricant and metal within the engine.

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Picture 10

1.6 PURPOSE OF PCV SYSTEM

The purpose of a positive crankcase ventilation (PCV) system, is to take the vapour

produced in the crankcase during the normal combustion process, and redirecting them into the

air/fuel intake system to be burned during combustion. These vapours dilute the air/fuel

mixture, they have to be carefully controlled and metered so as not to affect the performance of

the engine. This is the job of the positive crankcase ventilation (PCV) valve.

At idle, when the air/fuel mixture is very critical, just a little of the vapours are allowed

into the intake system. At high speed when the mixture is less critical and the pressures in the

engine are greater, more of the vapours are allowed into the intake system. When the valve or

the system is clogged, vapours will back up into the air filter housing or at worst, the excess

pressure will push past seals and create engine oil leaks. If the wrong valve is used or the system

has air leaks, the engine will idle rough, or at worst engine oil will be sucked out of the engine.

1.7 POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM OPERATION

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In this system, any crankcase vapours produced are directed back into the base of the

carburetor to be reburned. This system is called a closed system air is drawn through the

carburetor air cleaner assembly, into the engine valve compartment and crankcase. These

vapours are then drawn up through a vacuum-and-spring-controlled ventilating valve

(PCV valve) and into the intake manifold. The vapours are then mixed with the air-fuel

mixture and burned in the combustion process.

Picture 11

1.8 EXHAUST GAS RECIRCULATION SYSTEM (EGR)

When combustion temperatures are in the range 2,200 to 2,500 o F, nitrogen mixes

with oxygen and produces oxides of nitrogen (NOx). This type of emission has a detrimental

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effect to environment. The method used to reduce oxides of nitrogen is to cool down the

combustion process. This is done by using an Exhaust Gas Recirculation (EGR) valve. The

EGR valve is controlled either by an engine vacuum or a coolant temperature valve, whereas,

ECM unit in modern automobiles is controlled by a computer.

Picture 12

1.9 PURPOSE OF (EGR) VALVE

The purpose of the exhaust gas recirculation valve (EGR) valve is `to meter a small

amount of exhaust gas into the intake system, this dilutes the air/fuel mixture so as to

lower the combustion chamber temperature. Excessive combustion chamber temperature

creates oxides of nitrogen, which is a major pollutant. While the EGR valve is the most

effective method of controlling oxides of nitrogen, its design adversely affects engine

performance. The engine is not designed to run on exhaust gas. For this reason the amount of

exhaust entering the intake system has to be carefully monitored and controlled. This is

accomplished through a series of electrical and vacuum switches and the vehicle computer.

Since EGR action reduces performance by diluting the air /fuel mixture, the system does not

allow EGR action when the engine is cold or when the engine needs full power.

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Picture 13

2.0 INTERCOOLER UNIT

2.1 INTRODUCTION

Intercoolers are used to cool the turbocharged air and are either of the air-cooled type or

the water-cooled type. Intercooler is located above the cylinder head.

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Picture 14

2.2 TYPES OF INTERCOOLER UNIT

2.2.1 AIR COOLED TYPE INTERCOOLER

The air-cooled type intercooler utilizes the vehicle wind stream or an engine cooling fan.

This system is simple, as shown below. The intercooler may be installed at various locations

depending on the vehicle model.

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Picture 15

2.2.2 WATER COOLED TYPE INTERCOOLER

The purpose of the water-cooled type intercooler is the same as that of the air-cooled

type. The cooling system of the water-cooled type intercooler is independent from the engine

cooling system. The coolant passing through the intercooler is forced-fed to the sub radiator by

an electric pump. After being cooled by the ram air, the coolant is returned to the intercooler.

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Picture 16

3.0 CATALYTIC CONVERTER

3.1 INTRODUCTION

Catalytic converters provide another method of treating exhaust gases. It

is located in the exhaust system between the engine and the muffler. They are

used to convert harmful pollutants such as HC, CO and NOx into harmless

gases. A catalyst is a material that causes a chemical reaction without becoming

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part of the reaction process. The catalyst is not chemically changed in the

process. The catalyst which is used on the catalytic converter depends on the type of the pollutant

being removed. When the exhaust gases are passed through a coated honeycomb core, the HC

and CO react with the oxygen in the air. The result is a formation of water and carbon dioxide.

The metal rhodium is to reduce NOx into nitrogen and oxygen.

The reaction within the catalyst produces additional heat in the exhaust system. This

additional heat (>1,600 Fahrenheit) is necessary for the catalyst to operate correctly. Because of

these high temperatures, catalytic converters are made of stainless steel. This shield is used to

protect the underbody from excessive heat. It is important that only unleaded fuel is to be

used with a catalytic converter. Leaded gasoline will destroy the effectiveness of the catalyst as

an emission control device

Picture 17

3.2 TYPES OF CATALYTIC CONVERTER

There are two types of catalytic converter:

a)Two-way converter

b)Three-way converter

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Both types can employ either a monolith or a pellet design. The pellet converter

consists of two louvered sheet-metal retainers which they called beads. The monolith converter can

have a catalyst made of either ceramic of metal. The designs are shown in diagrams respectively

I. TWO-WAY CONVERTER

The two-way catalytic converter reduces carbon monoxide and hydrocarbon particles. It

does not reduce any nitrogen oxide emissions. Here, only platinum and palladium are used as

catalysts to reduce hydrocarbon and carbon monoxide.

Picture 18

II. THREE-WAY CONVERTER

The three-way converter is designed to reduce nitrogen oxide emissions. Additional

catalyst bed which is coated with platinum and rhodium is used. The bed not only helps to reduce

HC and CO but also lowers the level of nitrogen oxide emissions. Below is the diagram of a three-

way converter.

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Picture 19

4.0 TURBOCHARGER

4.1 INTRODUCTION

The turbocharger is basically an air pump that is designed to utilize some of the fuel’s

energy that would otherwise be wasted in the form of exhaust gases. The exhaust gases drive the

turbine wheel, which is coupled to the compressor wheel by means of a shaft. This compressor

wheel is driven at high speeds, forcing more air into the cylinders. Since turbochargers use the

wasted energy of the exhaust gases, the power output of the engine can be increased with less

power loss.

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Turbochargers are used in both gasoline engines and diesel engines. Their principle of

operation is the same. The turbocharger is provided with a waste gate valve to control the boost

pressure on the intake air. Some turbocharged engines are also equipped with an intercooler to

lower the intake air temperature. This prevents engine knocking and improves air intake

efficiently.

Picture 20

4.2 TURBOCHARGER COMPONENTS

The turbocharger consists of the turbine housing, compressor housing, center housing,

turbine wheel, compressor Wheel, full floating bearings, waste gate valve, actuator, etc.

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Picture 21

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4.2.1 TURBINE AND COMPRESSOR WHEEL

The turbine wheel and the compressor wheel are mounted on the same shaft. Exhaust gas

flows from the exhaust manifold to the turbine wheel, and the pressure of the exhaust gas turns

the turbine wheel. When the turbine wheel turns, the compressor wheel also turns, forcing the

intake air into the cylinders. Since the turbine wheel is exposed directly to the exhaust gases, it

becomes extremely hot and since it rotates at high speeds, and must be heat-resistant and

durable, it is made of an ultra-heat-resistant alloy or ceramic.

Picture 22

4.2.2 CENTER HOUSING

The center housing supports the turbine and compressor wheels via the shaft. Inside the

housing, engine oil is circulated through channels that are provided for lubricating the shaft and

the bearing. Also, engine coolant is circulated through coolant channels that are built into the

housing in order to prevent engine oil temperature from rising.

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Picture 23

4.2.3 FULL FLOATING BEARINGS

Since the turbine and compressor wheels turn at speeds of up to 100,000 rpm, full-

floating bearings are used to ensure the absorption of vibrations from the shaft and lubrication of

the shaft and bearings. These bearings are lubricated by the engine oil and roate freely between

the shaft and the housing to prevent seizing during high-speed operation. Engine oil is prevented

from leaking by two ring seals or by a mechanical seal and a ring seal fitted to the shaft.

Picture 24

4.2.4 WASTE GATE VALVE AND ACTUATOR

The waste gate valve is built into turbine housing. Its purpose is to reduce the boost

pressure when this begins to rise too high. When this valves opens, part of the exhaust gas by-

passes the turbine wheel and flow to the exhaust pipe. The opening and closing of the waste gate

valve is controlled by the actuator.

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Picture 25

4.2.5 BLOWS-OFF (BYPASS) VALVES

The Blow-Off valve (BOV) is a pressure relief device on the intake tract to prevent the

turbo’s compressor from going into surge. The BOV should be installed between the compressor

discharge and the throttle body, preferably downstream of the charge air cooler (if equipped).

When the throttle is closed rapidly, the airflow is quickly reduced, causing flow instability and

pressure fluctuations. These rapidly cycling pressure fluctuations are the audible evidence of

surge. Surge can eventually lead to thrust bearing failure due to the high loads associated with it.

Blow-Off valves use a combination of manifold pressure signal and spring force to detect when

the throttle is closed. When the throttle is closed rapidly, the BOV vents boost in the intake tract

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to atmosphere to relieve the pressure; helping to eliminate the phenomenon of surge.

Picture 26

5.0 SUPERCHARGER

5.1 DEFINITION 

Supercharger is an air compressor used for forced induction of an internal combustion engine.

The greater mass flow-rate provides more oxygen to support combustion than would be available

in a naturally aspirated engine, which allows more fuel to be burned and more work to be done

per cycle, increasing the power output of the engine. A supercharger is typically powered

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mechanically by belt, gear, or chain-drive from the engine's crankshaft. There are three (3) types

such as Centrifugal supercharger, Roots supercharger and Vane Type supercharger.

Picture 27

5.2 SUPERCHARGER OPERATION

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5.2.1 CENTRIFUGAL SUPERCHARGER

The centrifugal supercharger has an impeller equipped with curved vanes. As the engine drives

the impeller, it draws air into its center and throws it off at its rim. The air then is pushed along

the inside of the circular housing. The diameter of the housing gradually increases to the

outlet where the air is pushed out.

Picture 28

5.2.2 ROTOR ( ROOTS) SUPERCHARGER

The roots supercharger is of the positive displacement type and consists of two rotors

inside housing. As the engine drives the rotor, air is trapped between them and the housing. Air

is then carried to the outlet where it is discharged. The rotors and the housing in this type of

supercharger must maintain tight clearances and therefore are sensitive to dirt.

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Picture 29

5.2.3 VANE- TYPE SUPERCHARGER

The vane-type  supercharger  has  an  integral  steel  rotor  and shaft, one end supported

in the pump flange and the other end in the cover, and revolves in the body, the bore of which is

eccentric to the rotor. Two sliding vanes are placed 180 degrees apart in slots in the rotor and are

pressed against the body bore by springs in the slots. When the shaft rotates, the vanes pick up a

charge of air at the inlet port, and it is carried around the body to the outlet where the air is

discharged. Pressures produced by the wedging action of the air, as its forced toward the outlet

port by the vane. The term supercharger generally refers to a blower driven by a belt, chain, or

gears.  Superchargers are used on large diesel and racing engines.

Picture 30

The supercharger raises the air pressure in the engine intake manifold. Then, when the

intakes valves open, more air fuel mixture (gasoline engine) or air (diesel engine) can flow into

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the cylinders. An intercooler is used between the supercharger outlet and the engine to cool the

air and to increase power (cool charge of air carries more oxygen needed for combustion ). A

supercharger will constantly produce increased pressure at low engine speed because it is

mechanically linked to the engine crankshaft. This low engine speeds because it is mechanically

linked to the engine crankshaft. This low – speed power and constant throttle response is

desirable for passing and entering interstate highways.

5.3 SUPERCHARGER CONSTRUCTION

Picture 31

At 1 shown the inlet pipe for conducting the explosive mixture into the supercharger and

against the vanes 3 of the impeller 2. The impeller 2 is mounted on a shaft 4 and is operated at

high speed through suitable gearing, partly shown at 5 and 6, from the crankshaft of the engine.

The spacing of the impeller from the engine proper depends upon the space required for the

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gearing 5, 6 and the inner wall 7 of the impeller casing extends at the right angles to the impeller

shaft for a distance equal to the diameter of the impeller. From the point 8 the inner wall 9 of the

casing is slanted sharply toward the engine 10 and forms, with the outer wall of the impeller

casing, the slanting diffuser section 11 comprising the principal movement of the supercharger.

Ordinarily, the diffuser section is radial to the impeller shaft but it will be seen that the

construction is substantially conical in shape, thus allowing the collector pipe 12, into which the

diffuser section merges, to be placed close to the engine 10 to which it is secured at 13 forming

with the engine a housing 17 for the gear train. The collector pipe 12 is partially separated from

the diffuser section by a web 14 forming an extension of the wall 9, this structure serving to

reduce the necessary overall diameter of the supercharger. The slanting diffuser section thus

leaves the spaces at 16 radially of the impeller and within the engine compartment free for

mounting other accessories.

The foregoing construction which provides for terminating the impeller 2 at a point

within the diffuser casing 11, which is intermediate the fuel inlet pipe 1 and the collector pipe 12,

so that the line of vertical axis of the impeller which is indicated at 15 crosses the diffuser casing

at a point between the extremity of the impeller 2 and the collector pipe 12, furnishes a very

advantageous result.

Particles of liquid fuel reaching the impeller are thrown off the impeller vanes by

centrifugal force in the direction of the axial line 15, and thus cross the main stream of fuel gas

within the diffuser casing. The result is that instead of adhering to the inner faces of the diffuser

casing, particles of liquid fuel become thoroughly mixed with the main fuel stream before

entering the collector pipe 12.

5.4 SUPERCHARGER CONTROL

A supercharger control system for an internal combustion engine wherein a control valve

is advantageously placed in the inlet bypass of the supercharger. The control valve is activated

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and controlled by a combination of the throttle position and the pressure differential within the

intake manifold. A linkage including a lost-motion mechanism connects the control valve to the

engine throttle valve for limiting the closing of the control valve for supercharging to

corresponding open positions of the throttle valve. A pressure differential device urges the

control valve toward a closed position for supercharging upon the occurrence of a lower pressure

at a venturi portion of the air intake than at a portion upstream thereof at the supercharger outlet.

5.5 SUPERCHARGER COMPONENTS

Picture 32

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RUJUKAN:

Anshuman Panda (2010). Supercharger-Seminar Report. India: Visvesvaraya Technological

University, Belgaum.

Muhd. Amir Hakim (2011). Turbocharger and Supercharger. Kuala Lumpur: Universiti Kuala

Lumpur-Malaysian France Institute.

Panel-Panel GiatMara (2014), WIM TP-300-3 Juruteknik Automotif. Kuala Lumpur: Institut

Kemahiran Mara,

Panel-Panel Penulis Politeknik. Internal Combustion Engine Module 7 & 11. Kuala Lumpur:

Politeknik Kementerian Pengajian Tinggi.

Panel Penulis (2013). WIM TP-300-3 Automotive After Sales and Services.

Technical Education for Automotive Mastery (1997). Turbocharger and Supercharger Training

Manual Volume 2. Tokyo: Toyota Motor Corporation.

Tim Gilles (2003). Automotive Service Inspection, Maintenance,Repair 2nd Edition. New York:

Cengage Learning.

http://ken-gilbert.com/.../07.%20Evaporative%20Emission%20Control%20Sys...

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