GOVERNMENT ENGINEERING COLLEGE AURANGABAD

(BIHAR)

AUTOMOBILE ENGINEERING
PROf. CHANDAN KUMAR
PROf. CHANDAN KUMAR
DEPARTMENT Of MECHANICAL ENGINEERING
GOVERNMENT ENGINEERING COLLEGE ,AURANGABAD, BIHAR
(SCIENCE, TECHNOLOGy AND TECHNICAL EDUCATION
DEPARTMENT, GOVT. Of BIHAR, PATNA, )
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MODULE -1

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What is Automobile or Automotive?
• Automotive Engineering is a specialization of Mechanical
Engineering and incorporates the elements of Safety, Mechanical and
Electrical Engineering in the Design and Manufacturing of
Automobiles.
• It is also an Introduction to Vehicle Engineering, which includes
cars, motorcycles, trucks & buses, etc.
• These branches deal with the design, development, manufacturing,
testing, repair, and servicing of automobiles such as cars, trucks,
motorcycles, scooters, etc., and related sub-engineering systems.
• A self- propelled passenger vehicles that usually has four wheels and
internal combustion engine, used for land transport. Also called
motorcar.
• An automobile is a vehicle that is capable of propelling itself.
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Based on purpose:-
1. Passenger Vehicles: - These automobile carry passengers.
Example- Buses, Passenger train, cars
2. Goods Vehicles:- These vehicles are used transportation of goods
from one place to another.
Example- Goods lorry, Goods carrier.

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Type of Automobiles:-
The automobiles are classified in the following ways:-
1. On the Basis of Load or capacity:
• Heavy transport vehicle (HTV) or heavy motor vehicle (HMV) :– large trucks
and buses.
• Light transport vehicle (LTV), Light motor vehicle (LMV) :- cars and jeeps.
• Medium vehicles (MMV) :- small trucks mini buses.
2. On the Basis of Wheels:
When considering the types of cars and other vehicles, we can classify them based
on wheels.
• Two-wheeler vehicles. Example- Scooter, motorcycle, etc.
• Three-wheeler vehicles. Example- Auto-rickshaw, Three-wheeler scooter for
handicaps and tempo, etc.
• Four-wheeler vehicles. Example-Car, jeep, trucks, buses, etc.
• Six-wheeler vehicles. Example- Big trucks with two gear axles.
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3. On the basis of Fuel Used:
When discussing the types of automobile industry, the fuel used is a
significant factor.
• Petrol vehicles- Examples- motorcycles, scooters, cars, etc.
• Diesel vehicles- Examples- trucks, buses, etc.
• An Electric vehicle that uses the battery to drive.
• Steam vehicle. Examples- an engine which uses steam engine.
• Gas vehicle. Examples- LPG and CNG vehicles, where LPG is
liquefied.
4. Passenger Vehicle:
• Cars, Bus, Taxi, etc. Goods Vehicle: Trucks, Tempos, Containers, etc.
5. Special Purpose Vehicle:
• Ambulance, Fire brigade, etc.
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6. On the basis of body style:
• Sedan, Hatchback, Suv car.
• Coupe car Station wagon Convertible.
• Van Special purpose vehicle, e.g., ambulance, milk van, etc.
7. On the basis of Transmission:
• Conventional vehicles with a manual transmission, e.g., cars with
five gears.
• Semi-automatic.
• Automatic: In automatic Transmission, gears are not required to be
changed manually.
8. On the basis of Drive:
• Left-hand Drive.
• Right-hand Drive.
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9. On the basis of Driving Axle:
• Front-wheel Drive- Swift, Tata Nexon Creta, etc.
• Rear-wheel Drive-Tata Yodha,
• All-wheel Drive – Land Rover Defender, Audi, BMW, Mercendes-
Benz.
10. Position of Engine:
• The engine in Front – Most vehicles have the engine in the front.
Example: most of the cars.
• The engine in the Rear Side, very few vehicles have the engine located
in the rear—for example, a Nano car.

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Vehicles Layouts:-
Vehicles layouts roughly divided into three categories:
1. FWD (front wheel drive).
2. RWD (rear wheel drive).
3. 4WD (four wheel drive).

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Fig.: FWD, RWD, AWD

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1. FWD (Front Wheel Drive):-
• FWD means that the power from engine is delivered to the front
wheels.
• FWD is a form of engine and transmission layout used in motor
vehicles, in which the engine drives the front wheel only.
• In FWD, the front wheels are pulling while the rear wheels don’t
receive any power.
• FWD vehicle are better fuel economy.
• Weight of the engine is located above the driving wheels, FWD
vehicle can maintain better traction in the snow.
• Example:- Family Sedan and Hatchback have FWD such as Toyota
Corolla, Hyundai Elantra and Honda Accord.
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Advantages:-
• Its have lower towing capacity than RWD.
• Its have better traction for cornering and less risk of loosing control.
• It is more fuel efficient.
• More space for passenger and luggage as the engine is located at the
front of the car.

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Disadvantages:-
• Its have worse acceleration than RWD.
• Total weight of the engine up front , FWD can make handling more
difficult.
• It is difficult to get a car moving from a stop when driven in slippery
condition (such as ice and snow).
• The engine is located in front of the car, it can be damaged more easily
in a collision.

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2. Rear Wheel Drive (RWD):-
• RWD means that the engine power is delivered to the rear wheels
which push the car forward. The front wheels do not receive any
power.
• Weight of the RWD vehicle is more evenly spread than many FWD
vehicles, there’s better balance of weight.
• That’s why most of the sports car are based on the RWD.
• In this layout, the placing of an engine, clutch and gear box in the
back. So taking the space in the boot.
• In these type of layout more than 50% of the weight is on the rear axle.
• Clutch, gear box and engine and final drive from a single unit.
• There is one disadvantages of RWD is they do not perform well in
poor weather condition such as rain or snow .
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• Example:- BMW 3 series, Jaguar XE, BMW i4, Ford Mustang.
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Advantages:-
• Excellent traction is available while climbing hills.
• A larger passenger space is available for the given length of body.
• Very compact and accessible power and transmission assembly is
provided.
• Lot of weight at the back improves acceleration and braking, rear
wheels and disc brakes can be designed to take a bigger amount of
braking due to weight distribution to the rear.
• Passenger are comfortable from engine, noise heat and fumes.
• It can be more stable and traction control.
• Tires are longer lasting.
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Disadvantages:-
• Less fuel efficiency due to more weight and large engine is needed to
propel the car in RWD setup.
• Loss of power due to complexity (30% power output can be loss).
• At high speed, relatively high proportions of weight at the rear axle
will make the car unstable at speed. There is a strong tendency for the
vehicle to oversteer (less grip surface due rear drive can push the rear
out of line).
• Less interior space due to more room needed for transmission tunnel
and driveshaft.

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3.Four Wheel Drive (All Wheel Drive) :-
• Four wheel drive is also called 4*4.
• It refer to a two-axel vehicles drivetrain capable of providing torque to
all of its wheels simultaneously.
• Here, the Torque supplied to both the axles.
• In this arrangement all the four wheels of the vehicle are driven by the
engine thus making the entire vehicle weight available for traction.
• These four wheel drive vehicles are very useful on Hill station if one
of the wheel slipping or skidding then the other axle wheel transmit
the tractive force to the vehicle.
• The steering of the four wheel drive is hard to operate compared with
other type of drive.
• Example:- Thar, Jeep Wrangler, Lamborghini, Mahindra Thar, Force
Gurkha, Jeep compass, Toyota Fortuner.
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Advantages :-
• Traction is nearly doubled compared to a two-wheel drive layout.
• Handling characteristics in normal conditions can be configured to
emulate or RWD.
• Gives sufficient power, this results in unparalleled acceleration and
drive ability on surfaces with less than ideal and superior engine
braking on loose surfaces.

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Disadvantages:-
• The manufacturing cost of the vehicle is high.
• More component and complicate transmission.
• Increased power-train mass, rotational inertia and power transmission
losses.
• Increased fuel consumption compared to 2WD.

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 ON THE BASIS OF DATA FWD RWD

Engine Mounting Front side Front or centre or rear side

Power Transmission Front wheel Engine is mounting on that sides

Traction (grip in the road) Gripping is Good on the road Less as compared to FWD.

Handling (on the running condition) Not good as compared to RWD Good.
(during turning condition vehicles is
unbalanced due to power
transmission and steering both are
mounted on the front wheel)
Adverse weather condition(snow, Good Not good
muddy area)
Smoothing Not good (at high speed) good

Space inside car More less

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ON THE BASIS OF DATA FWD RWD

Manufacturing Easy (no. of item is less and all Difficult

engine items are one unit)
Weight Less More

Tyre life Less More

Mileage More (loss is less) Less

Maintenance and service Less More

Hill Riding Easy Difficult

Cost Less More

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Vehicle construction and components:-

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The main components of an automobile refer to
the following components:-
• Frame
• Chassis
• Body
• Power unit
• Transmission system

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• An automobile is made up of mainly two units are:-
1. Chassis
2. Body
• Frame + Base components = Chassis.
• Chassis + Body = Vehicle.

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 Frame:-
• The frame is the skeleton of the vehicle. It servers as a main
foundation and base for alignment for the chassis.
• Types:-
1. Conventional frame
2. semi- integral frame
3. Integral or untidiest frame.

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 Fig. Frame

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Basic component of a vehicles:-

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Chassis of a vehicles:-

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What is Chassis?
Chassis:-
• A chassis is the framework that a vehicle is built on.
• The supporting frame of a structure.
• If the frame contains the base components its called as chassis.
• The components are like Engine, radiator, clutch, gearbox, silencer,
road wheels, fuel tank, wirings, differential units, etc.
Body:- Body is the super-structure of the vehicle and it is bolted to the
chassis.

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Car body style:-
• The easiest way to define a vehicle is by how it looks.
• What's the first thing we notice when a vehicle comes toward in the
street? Its shape. That's called the "body style”.
• Body style is the easiest way to categorize a vehicle.
• Types:- Hatchback, Coupe, Convertible, Sedan, Pickup Truck,
SUV, Minivan, Sports car, etc.

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What is frame?
• A vehicle frame is the main supporting structure of a motor vehicle.
• The various main assemblies like engine, clutch, gear box, suspension
system, steering system and all other major parts are mounted on
frame.
• It is made of steel section and is strong enough to withstand the load.
• As well as light in weight to reduce dead weight on the vehicle.

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Fig. Frame of a Vehicles

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Types of Frame:-
• Conventional frame
• Integral of Frameless Construction
• Semi- Integral frame

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Conventional Frame:-
• A conventional frame is one of the earliest kinds of frame.
• Its construction details having two longitudinal rails interconnected
by many lateral/cross braces.
• The lateral and cross members provide rigidity to the structure.
• Application :- Heavy vehicles, some SUV.
Construction:-
• It has two long side member and 5 and 6 cross member joined together
with the help of rivets and bolts.
The frame section are used generally:-
• Channel section- Good resistance to bending.
• Tubular section- Good resistance to Torsion.
• Box section- Good resistance to both bending and Torsion.
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Fig.:- Conventional Frame

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Integral or frameless construction:-
• In this type, frame is totally discarded and different units are fixed to
the body itself, so it is called as frameless construction.
Advantages:-
• More strength and stiffness.
• Light in weight.
• No body rattles.
• Improved vehicle performance and road holding capacity.
• Low centre of gravity / less height.
• Cheaper if manufactured in mass quantity.

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Disadvantages:-
• Expensive to repair if car involved in an accident.
• Greater chances of injury to drive on collision.
• Use of this structure is limited to only small cars.
• Life is limited.
• It is more expensive to introduce changes in body styling.

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Half integral or Half frame:-
• In some of the vehicles, half frame is fixed at the front end on
which engine, gear box and suspension s mounted.
• This frame is bolted to the floor and the rear portion of floor work as
floor of the body. This type of frame is used in old Fiat car.
Advantages:-
• In the event of an accident, the front half frame can be taken out easily
for replacement instead of replacing the complete chassis frame.

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What is chassis?
• A Chassis is the load bearing framework that supports the vehicle’s
body and other components.
• A vehicle without body is called chassis.
• An automotive chassis comprises a framework to support the body,
engine and other components that make up automobiles.
• It leads the whole vehicle support and rigidity.
• It is the back bone of the vehicle.

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The components of the chassis:-
• Frame
• Power plant (engine)
• Transmission system (clutch, gear box, propeller shaft, differential).
• Axles
• Wheels and Tyres
• Suspension
• Controlling system like Braking, steering, etc.
• Also electrical system parts are mounted on the chassis frame.

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Classification of chassis:-
According to control:-
• Conventional control chassis
• Semi- forward control chassis
• Full forward control chassis
According to fitting of an Engine:-
• Engine at front
 longitudinal
Transverse(cross)
• Engine at Rear
• Engine at centre
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Fig.:- Types of a Chassis

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PROF. CHANDAN KUMAR (MECH. ENGG. DEPT.) GOVT. ENGG.
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Fig:- Engine at a Front

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Fig:- Engine at a Rear

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What is Vehicles Aerodynamics?
• Aerodynamics means it is the branch of science of dynamics concerned
with Studying the Motion of Air, particularly when it interacts with a
solid objects.
• Aerodynamics is the way of air moves around things.
• Study of the properties of moving air and the interaction between the
air and solid bodies moving through it.
Why the Automotive is Aerodynamics?
• To improve the stability of a stream lining is done to automobile body
which is called as aerodynamics shapes.
• This is done to minimize air resistance when the automobile is in motion.
• Better mileage and Higher speed.
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Fig:- vehicles is Aerodynamics

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Need of Aerodynamic:-
• To increase stability of vehicles.
• To improved speed.
• To improved fuel economy.
• To reduce air noise.
There are two forces acting on a moving vehicles:-
1. Drag force
2. Lift and Down force

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Drag force:-
• Drag is an aerodynamics resistance to the motion of the object through the
fluid.
• The component of aerodynamics force that is opposed to the motion is the
drag.
• It takes some energy to move the car through the air. This energy is used to
overcome a force is called Drag.
• Drag, in vehicles aerodynamics, is comprised primarily of three forces:-
1. Frontal pressure:- The effect created by a vehicle body pushing air out
of the way.
2. Rear vacuum or (flow detachment):- The effect created by air not being
able to fill the hole left by the vehicle body.
3. Boundary layer:- The effect of friction created by slow moving air at the
surface of the vehicle body (thin layer of air flows around a vehicles
body).
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Lift and Down force:-
• Vertical component of the drag force is a called lift force.
• Additional drag component caused by the generation of lift.
• It is not uniform but varies from root to tip.

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PROF. CHANDAN KUMAR (MECH. ENGG. DEPT.) GOVT. ENGG.
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Streamlining of a car body:-
• It is technique that reduces the drag and improves aerodynamics.
• Streamlining is generally aimed at reducing air resistance as the
airplane or car or other vehicle moves through the air.
• Reducing air resistance improves fuel efficiency, potential speed, and
various other things.
• While air resistance is a key factor, particularly for airplanes, there are
other practical factors that must be considered in the design of the
vehicle, such as payload, appearance , comfort for passengers, size,
cost, cooling, performance, etc.

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Significance of Aerodynamic Body Shape:-
• Air drag is reduced.
• Aerodynamics lift acting in vertical upward direction is reduced.
• Air eddies are not formed.
• Cross wind force acting in lateral direction is minimized.
• Speed of the automobile is maintained.
• Obtained best fuel economy.

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IC Engine component:-
Name of the component Method Materials

Piston Casting method Aluminium Alloy

Piston ring Pot casting method Cast Iron + High Elastic Materials

Crank shaft Casting method Alloy steel

Fly wheel Casting method Cast iron

Cam shaft Grinding + case hardening method Plain carbon steel

Cylinder block Casting + Forging + Machinery Ductile cast iron and low carbon
method steel

Cylinder head Casting method Aluminium alloy

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Name of the component Method Materials

Connecting rod Forging method Low carbon steel

Crank case Casting method Iron, Aluminium and Magnesium
Intake and Exhaust valve Forging, Machining and Fabrication Stainless steel, Nickle, Chromium,
method Phosphorus, Bronze, Monel steel
Spark plug
Bearing Forging, heat treatment, turning, Aluminium alloy, copper alloy and
grinding, injection molding and crome steel
stamping method.
Carburetor Extrusion, sand casting and molding Aluminum or zinc.
method
Fuel injector Injection molding method Carburizing steel or Maraging steel
Intake and Exhaust manifold Die casting, drilling, bonding, core Aluminium alloy
meltout method.
Gudgeon / Piston pin Heat treatment method Plain carbon steel
Push rod Projection welding
Rocker arm Forging method Medium carbon steel
Timing chain PROF. CHANDAN KUMAR (MECH. ENGG. DEPT.) GOVT. ENGG.
Steel
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Timing belt Synthetic rubber and nylon

Name of the component Method Materials

Gasket Paper, rubber, silicon, metal, cork,

neoprene, nitrile rubber, fibre glass,
plastic polymer

Oil pan Low carbon steel and aluminium

alloy
Muffer Cast iron, stainless steel, mild steel,
carbon steel
Catalytic converter Platinum, Palladium and Rhodium
Valve spring Oil tampered wire, steel, stainless
steel, copper, bronze, brass, exotic
alloys

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Basic component of IC Engine:-
1. Cylinder Block and Cylinder Head:-
• Cylinder block is the main supporting structure for engine which
contains piston, cylinder arrangement, inside which the combustion of
fuel takes place.
• Cylinder head is the structure mounted on the cylinder block. It
contains valve mechanism (valve, valve seat, cam & Follower, etc.)
spark plug or fuel injector, lubrication & cooling passages (like fins or
water jackets).
• Cylinder head is held tight to the cylinder block by number of studs,
bolts and gaskets.

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2. Cylinder :-
• Cylinder is a cylindrical vessel or space inside the cylinder block in
which piston makes the reciprocating motion as well as the
combustion of fuel take place.
• Cylinder is made of aluminium alloy for light duty vehicles and cast
iron for heavy duty vehicles .
3. Piston:-
• Piston is a cylindrical component fitted into the cylinder, to provide
the reciprocating motion.
• Piston transmit the force of explosion to the crank shaft via connecting
rod. (sudden burning of fuel)
• Piston also provide the slots to the piston rings.
• Piston are made of aluminium alloys & stainless steels.
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4. Piston ring:-
• Piston rings are the expandable split rings fitted into the slots
around the piston to serve the following function:-
To provide/ maintain the air tight seal between the piston and the
cylinder wall.
To provide a means to transmit surplus heat from the piston to the
cylinder walls.
To provide the lubrication between piston and cylinder walls for
smooth functioning of piston.
• Piston rings are commonly made of cast iron and forged and heat
treated steels.

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• Types of piston rings:-
• Automotive piston engine typically have three to five rings per
cylinder.
• In case of three piston rings, the top two rings- known as
“compression rings” and the bottom ring- known as “oil control ring”.
• Compression rings:- compression rings are primarily used for
sealing the combustion chamber.
• Oil control ring:- oil control ring is primarily used for controlling
the supply of oil to the cylinder wall, in order to lubricate the piston.
5. Combustion chamber:-
• A combustion chamber is the area or enclosed space within the
cylinder, where the fuel-air mixture is ignited i.e., combustion of air-
fuel mixture takes place.
• In IC Engine, space above the piston with in the cylinder is taken as
combustion chamber.
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6. Inlet and Exhaust Manifolds:-
• Inlet manifold is passage or pipe used to supply the fuel-air mixture
to the engine cylinder.
• Exhaust manifold is passage or pipe used to remove the burn of flue
gases from the engine cylinder.
7. Inlet and exhaust valves:-
• Inlet and Exhaust valves are usually mushroom shaped poppet valves
with conical seating surfaces.
• The faces of the valves and its seat on the cylinder head are at angle of
30 or 45 degree.
• Inlet and exhaust valves are made of nickel, chromium based steels.

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8. Spark plug:-
• A spark plug is an electrical device that fits into the cylinder head of
IC engine & used to deliver the electric current (or spark) from an
ignition system to ignite the compressed fuel-air mixture in the
combustion chamber.
• Construction of spark plug :-
Spark plug is constructed by various components such as :-
Terminal nut
Ceramic insulator
Central electrode (made of copper)
Special conductive seal
Threads
Ground electrode PROF. CHANDAN KUMAR (MECH. ENGG. DEPT.) GOVT. ENGG. 64
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Note:-
• To produce spark, a spark gap is generally kept between central
electrode and ground electrode. (spark gap is 0.6 to 1.0mm)
• The sparking voltage at the spark plug is 10,000 to 15,000 volt.
9. Connecting rod:-
• Connecting rod is the “I”- cross sectional link used to transmit the
force given by the piston to the crank.
• Connecting rod has two ends- Big end and small end. Small end is
connected to piston with the help of gudgeon pin and Big end is
connected to crank with the help of crank pin.

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10. Crank and crank shaft:-
• Crank is a mechanical link which is used to converts the
reciprocating motion of piston into rotary motion and also used to
convert the force of piston into torque of crank shaft with the help of
connecting rod.
• Its one end is connected to connecting rod with the help of crank pin
and another end is cast to crank shaft.
11. Crank case:-
• Crank case is the lowest part of the cylinder block or engine used,.
• To support the cylinder block and other mountings.
• To stored the lubricating oil (called engine oil).
• To protect the engine parts against dust, moisture and splashing mud.

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11. flywheel:-
• Flywheel is heavy balanced disk at the end of the crank shaft to store
the energy during the power stroke and returns back, this stored
energy to piston during compression stroke for providing the uniform
motion of piston.

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What is VVT?
• A Valve Timing Diagram is a graphical representation of the opening
and closing times of intake and exhaust valves in an internal
combustion engine.
• It illustrates the relationship between the piston's position and the
valve events, crucial for engine performance.
• Proper timing enhances fuel efficiency, power output, and reduces
emissions, optimizing engine operation.

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Importance of Valve Timing Diagram:-
• The valve timing diagram is referred to when designing a 2-stroke or
4-stroke engine to ensure that the movement of the piston from the top
dead center (TDC) to the bottom dead center (BDC) aligns with the
optimal timing for the opening and closing of the intake and exhaust
valves.
• By carefully coordinating these valve actions with the piston's
position, the engine can achieve efficient and effective air intake,
combustion, and exhaust processes.
• The valve timing diagram serves as a blueprint to ensure that the valve
events occur at the right moments during the piston's stroke, ultimately
contributing to the engine's overall performance, power output, and
fuel efficiency.

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Fig.: Theoretical VVT Diagram

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• Suction Stroke: -The engine cycle commences with the suction stroke, where the piston, located at
the top dead center (TDC), moves towards the bottom dead center (BDC), causing the inlet valve
to open. This motion allows the air-fuel mixture (for petrol engines) or fresh air (for diesel engines)
to enter the cylinder until the piston reaches BDC.
• Compression Stroke:- Next is the compression stroke, where the piston moves from BDC to
TDC, compressing the air-fuel mixture (petrol engine) or fresh air (diesel engine). This
compression raises the pressure inside the cylinder, preparing it for efficient fuel combustion.
During this process, the inlet valve closes to seal the chamber for effective compression.
• Expansion Stroke:- The expansion stroke follows, ignited by the combustion of the fuel. The
combustion pushes the piston, located at TDC, towards BDC, releasing the pressure generated by
the combustion and generating output power.
• It's important to note that in petrol engines, combustion occurs due to the spark produced by the
spark plug, while in diesel engines, combustion happens due to the high compression provided
during the compression stroke, raising the temperature inside the cylinder to the auto-
ignition temperature of the diesel and air charge. In petrol engines, the air-fuel mixture enters the
cylinder during the suction stroke, whereas in diesel engines, fresh air enters during this stroke,
with fuel being sprayed by fuel injectors into the air.
• Exhaust Stroke:- Finally, the exhaust stroke takes place. After the expansion stroke, the piston,
located at BDC, moves towards TDC, and the exhaust valve opens to remove the residual
combustion gases from the cylinder. The exhaust valve closes once the piston reaches TDC,
completing the four-stroke engine cycle.

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Fig.:- Actual Valve Timing Diagram of 2
Stroke Petrol Engine

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Fig.:- Actual Valve Timing Diagram of 2
Stroke Diesel Engine

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Fig.:- Actual Valve Timing Diagram of 4 -
Stroke Petrol Engine

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Fig.:- Actual Valve Timing Diagram of 4
Stroke Diesel Engine

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PROF. CHANDAN KUMAR (MECH. ENGG. DEPT.) GOVT. ENGG.
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