This document provides an overview of automobile engineering topics including: - Types of internal combustion engines like 4-stroke, 2-stroke, Wankel engine. Engine components such as valves, pistons, connecting rods, crankshaft, and camshaft. - Fuel supply systems for gasoline and diesel engines including carburetors, fuel injection pumps, and various fuel injection technologies. - Lubrication, cooling, and classification of automobiles and their engines. - Construction of vehicles including chassis, body, frames, and powertrains. Working principles of 4-stroke engines are also explained diagrammatically.

1. . BMECME 702 R02 / MAUCME 702 R02
AUTOMOBILE ENGINEERING
THEORY AND PRACTICE
S. Ragul, M.E.
Research Associate
School of Mechanical Engineering
SASTRA UNIVERSITY
Thanjavur-613 402

2. UNIT - I ENGINES & COMPONENTS
IC Engines
4 stroke and 2 stroke SI & CI engine
Wankel engine
hybrid power trains
Fuel cells
Engine components - Valves, Valve actuating mechanisms(includes basics of Variable
Valve Timing and Lift Electronic Control), Piston & piston rings, Liners, Filters, Air
cleaners, connecting rod, Crank shaft, Cam shaft.

3. Fuel supply system
For SI & CI engine: Austin Classic Mechanical & Skinners Union Electrical fuel
pump
Solex carburetor
Fuel injection pump – Fuel feed pump.
Multi Point Fuel Injection, Common Rail Direct Injection, Fuel Stratified
Injection, Super Charger and Turbo Charger, Variable Geometry Turbocharger,
multistage turbo charging.
Governor and it types

4. Lubrication system
Objective
Requirements and types of lubricants
Lubricating systems ( petroil, splash, pressure, dry sump)
Cooling system
Necessity
Methods of cooling ( air and water)
Water cooling systems (thermo-syphon, pump circulation- all components
in detail), coolant, antifreeze.

5. Introduction
Mobile or motive is the one which can move.
Automobile is the one which can move by itself.
An automobile is a self-propelled vehicle.
It is driven by an internal combustion engine (also
called as prime mover)

6. The modern automobile is used for transporting equipment
unit.
The power from the engine is supplied to the wheels by the
transmission system through the clutch of fluid coupling.
It is used for transport of goods and passengers on ground.
Introduction cond.,

7. Auto
Automobile
Auto-car
Auto-buggy
Car
Motor
 Motor car
 Motor vehicle
 Motor coach
 Motor Wagon
 Horseless coach
The different names of automobile are ;

8. The design and development in cars of recent years
has provided the owners with;
Safer
Easier to drive
Comfortable
More reliable.

9. Automobile in India
The first car appeared in 1897.
For 50 Years from 1897, India was an Importer of automobiles.
The late Bharat Ratna Sir M. Visvesvaraya made an automobile
in India, but the government did not approve the plan.
In 1943 and 1944 two automobile factories were set up in India
namely;
Hindustan Motors Limited, Calcutta,
Premier Automobiles Limited, Bombay.

10. The sacrifice of German Engineer Rudolf Diesel is memorable
in Automobile and I.C. engine history.
He got very seriously injured when he successfully exploded
coal dust as fuel.
In 1913 although he invented Diesel engine using liquid fuel
‘Diesel’ but he committed suicide as he could not get financial
co-operation from his friend for his research and development.

11. Classification
Of
Automobiles

12. Classification of Automobiles
1. Based on Purpose
 Passenger Carriers
- Car, Jeep, Bus, Station wagon, etc.,
 Goods Carriers
- Truck, Pick up,.
 Special purpose
- Ambulance, Fire engine, Army
vehicles, Concrete mixer, etc.,

13. 2. Based on Fuel Used
Petrol Vehicle
- Motor cycles, Scooters, Cars, Station wagons.
Diesel Vehicle
- Trucks, Buses, etc.,
Gas Vehicle
- Coal gas turbine
Electric
- Using storage batteries
Steam
- Using steam engine

14. 3. Based on Capacity
HTV (Heavy Transport Vehicles) or HMV
(Heavy Motor Vehicles)
- Trucks, Buses, Dumpers.
LTV (Light Transport Vehicles)
- Pick up, Station Wagon
LMV (Light Motor Vehicles)
- Jeep, Cars.,
Medium Vehicle
- Tempo, Minibus, Small trucks.,

15. 4. Based on Construction
Single Unit Vehicle
Articulated Vehicles and Tractors.

16. 5. Based on Drive
Left hand drive
-Steering wheel fitted on left hand side
Right hand drive
-Steering wheel fitted on right hand
side
Fluid drive
-Vehicle employing torque converter,
fluid flywheel (or) hydro-matic
transmission.

17. 6. Based on wheel and axle
Two Wheeler
- Auto cycle, Mopped, Scooter, Motor cycle
Three Wheeler
- Three Wheel scooter, Auto rickshaw,
Tempo.
Four wheeler (4x2) and (4x4)
- Cars, Jeep, Station wagon, Pick up,
Trucks, Buses.
Six Wheeler (6x2) and (6x4)

18. 7. Based on suspension system
Conventional
- Leaf spring
Independent
- Coil spring, Torsion bar, Pneumatic.

19. 8. Based on body and number of doors
Sedan
- Two and four door types
Convertible
- Jeep, some imported cars
Station wagon
Delivery van/pick ups
Special purpose vehicles
- Ambulance, milk van, mobile
workshop, mobile hospital, etc..

20. 9. Based on Transmission
Conventional
- All Indian vehicle
Semi-automatic
- Most of British and Japanese vehicles
Automatic
- Most of the American vehicles

21. Classification
Of
Automobile Engines

22. A) Type of fuel used
 Petrol or Gasoline engine
 Diesel Engine
 Gas Engine
B) Cycle Of Operation
 Otto cycle engine
 Diesel cycle engine
 Dual combination cycle or semi-diesel
engine

23. C) Type of Ignition used
Spark ignition engine
Hot-spot ignition engine
Compression ignition engine
D) Method of fuel admission
Carburetor engine (Petrol)
Air injection engine (Diesel)
Airless or solid injection engine (Diesel)

24. E) Number Of Strokes per cycle
 Four stroke engine
Two stroke engine
F) Arrangement of cylinders
Vertical engine
Horizontal engine
Radial engine
V – engine
Opposed cylinder engine

25. G) Valve location
Overhead valve engine
Side valve engine
H) Type of cooling engine
Air cooled engine
Water cooled engine

26. I) Lubrication Systems
 Wet sump
 Dry sump
 Pressurized
J) Speed
 Slow Speed engine
 Medium Speed engine
 High Speed engine

27. K) Method of Governing
Hit and miss governed engine
Qualitatively governed engine
Quantitatively governed engine
L) Application
Stationary engine
Automotive engine
Marine engine
Locomotive engine

28. Vehicle
Construction

29. Components of Four Wheeler Automobile
 Chassis
 Body
 Frame
 Power unit
Transmission system

30. Chassis

31. An automobile is made of two main units namely;
Body
Chassis
• A vehicle arrangement without body is called Chassis.
• The chassis supports the body, engine and
transmission system.

32. The Chassis includes the following components
Frame
Front Suspension
Steering Mechanism
Radiator
Engine, Clutch, Gear box
Propeller Shaft
Rear Springs
Road Wheels
Differential, Half Shaft,
Universal Joint
Brakes and Braking System
Storage battery
Silencer
Shock absorbers, fuel tank,
petrol, hydraulic pipe cables
and some means of mounting
these components

33. Classification
Of
Chassis

34. I. According to the fitting of engine
(a) Full Forward
(b) Semi Forward
(c) Bus Chassis
(d) Engine at back
(e) Engine at centre

35. Type of
Chassis
Location of Engine Examples
Full Forward Outside the driver cabin
or seat
Cars, Mahindra
jeeps
Semi Forward One half is exactly in
the drivers cabin and the
other half in the front
but outside the drivers
cabin
Tata SE series of
vehicles
Bus Chassis Totally in the driver
cabin which provides
increase in floor area
Buses, Trucks

36. Type of
Chassis
Location of Engine Examples
Engine at back Back portion of the
chassis
Volkswagen cars,
Leyland bus of
England
Engine at
centre
Centre of the chassis Royal tiger world
master buses of
Delhi transport

37. II. According to Number of Wheels fitted in the vehicles and the Number of
driving wheels.
Type of Chassis No. of Wheels No. of Driving
Wheels
4X2 drive chassis 4 2
4X4 drive chassis 4 4
6X2 drive chassis 6 2
6X4 drive chassis 6 4

38. Characteristics of good Chassis
• Fast pickup
• Safety
• Dependability
• Quietness
• Power accessibility
• Low centre of gravity
• Load clearance
• Good springing
• Strength
• Durability
• Ease of control
• Speed
• Economy of operation
• Stability
• Braking ability
• Simplicity of lubrication

39. Four Stroke Engine
• Suction / intake
• Compression
• Power
• Exhaust

40. Suction / Intake Stroke
• Intake valve opens.
• Piston moves down, ½ turn of
crankshaft.
• A vacuum is created in the cylinder.
• Atmospheric pressure pushes the
air/fuel mixture into the cylinder.

41. Compression Stroke
• Valves close.
• Piston moves up, ½ turn of
crankshaft.
• Air/fuel mixture is compressed.
• Fuel starts to vaporize and heat begins
to build.

42. Power Stroke
• Valves remain closed.
• Spark plug fires igniting fuel mixture.
• Piston moves down, ½ turn of
crankshaft.
• Heat is converted to mechanical
energy.

43. Exhaust Stroke
• Exhaust valve opens.
• Piston move up, crankshaft makes ½
turn.
• Exhaust gases are pushed out
polluting the atmosphere.

44. Four Stroke Cycle Animation

45. Four Stroke engine working video

46. Two Stroke petrol engine working principle

47. Two Stroke Animation

48. 48
Two stroke diesel engine

50. Wankle engine (or) rotary combustion engine
The Wankel engine was designed in 1951 by
German engineer Felix Wankel for NSU
Motorenwerke AG (NSU), a German
automobile manufacturer.
The Wankel engine is an internal combustion
engine that uses the four strokes of a typical
Otto cycle (intake, compression, combustion,
exhaust) to create kinetic energy. This kinetic
energy is converted into rotational energy used
to spin the cars transmission and ultimately
propel the car.
Unlike it’s piston-driven counter-part, the
Wankel engine directly converts pressure into
rotating motion.

51. Various parts of wankle engine
INTAKE PORT - The entry point for the
gas into the engine.
OUTPUT SHAFT - Moves the
rotational kinetic energy from the rotor
to the rest of the car.
TRIANGULAR ROTOR - Divides the
chamber into intake, compression, and
combustion areas and supports the
energy of the system and the engines
gear set.

52. Various parts of wankle engine cond.,
SPARK PLUG - Provides the electric
energy used to combust the compressed
fuel.
HOUSING - Contains the combustion
reaction and guides the motion of the
triangular rotor.
FIXED GEAR - Gear attached to the
housing to ensure the correct movement
of the rotor within the housing.
OUTLET PORT - Exit area for ignited
gasoline.

53. Reuleaux triangle
There are many curves with constant width, but the simplest noncircular such
curve is named the Reuleaux triangle.

54. Working principle of wankle engine

55. Advantages
Most simpler and contain far fewer moving parts; for instance, it have no valves,
valve trains, etc.
In addition, the rotor spins the drive-shaft directly, so there is no need for
connecting rods, a conventional crankshaft, balance assemblies, etc.
All of this makes a Wankel engine much lighter, typically half that of a
conventional engine with equivalent power.

56. Challenges
There are some challenges in designing a rotary engine:
Typically, it is more difficult (but not impossible) to make a rotary engine meet
U.S. emissions regulations.
The manufacturing costs can be higher, mostly because the number of these
engines produced is not as high as the number of piston engines.
They typically consume more fuel than a piston engine because the
thermodynamic efficiency of the engine is reduced by the long combustion
chamber shape and low compression ratio.

57. Engine components

58. Cylinder block
This is a cast structure with cylindrical holes bored to guide and support the pistons
and to harness the working gases. It also provides a jacket to contain a liquid
coolant.

59. Cylinder head
This casting encloses the combustion end of the cylinder block and houses both the
inlet and exhaust poppet-valves and their ports to admit air– fuel mixture and to
exhaust the combustion products.

60. Crank case
This is a cast rigid structure which supports and houses the crankshaft and
bearings. It is usually cast as a mono-construction with the cylinder block.

61. Sump or oil pan
This is a pressed-steel or cast-aluminium alloy container which encloses the bottom
of the crankcase and provides a reservoir for the engine’s lubricant.

62. Piston
This is a pressure-tight cylindrical plunger which is subjected to the expanding gas
pressure. Its function is to convert the gas pressure from combustion into a
concentrated driving thrust along the connecting rod. It must therefore also act as a
guide for the small end of the connecting-rod.

63. Piston rings
These are circular rings which seal the gaps made between the piston and the
cylinder, their object being to prevent gas escaping and to control the amount of
lubricant which is allowed to reach the top of the cylinder.

64. Piston head
The shape of the top of the piston depends on the shape of its combustion chamber
and its compression ratio. Combustion chambers vary in shape depending on the
type of engine for which it is intended. The compression ratio can be changed by
using a piston with a different head design.

65. Gudgeon-pin or piston pin
This pin transfers the thrust from the piston to the connecting-rod small-end while
permitting the rod to rock to and fro as the crankshaft rotates.

66. Connecting Rod
The connecting rod is the intermediate member between the piston and the
crankshaft. Its primary function is to transmit the push and pull from the piston pin
to the crankpin and thus convert the reciprocating motion of the piston into the
rotary motion of the crank.

67. Crank Shaft
A crankshaft is used to convert reciprocating motion of the piston into rotatory
motion or vice versa. The crankshaft consists of the shaft parts which revolve in the
main bearings, the crankpins to which the big ends of the connecting rod are
connected, the crank arms or webs (also called cheeks) which connect the crankpins
and the shaft parts.

68. Cam shaft
The camshaft’s major function is to operate the valve train. Cam shape or contour is
the major factor in determining the operating characteristics of the engine. The lobes
on the camshaft open the valves against the force of the valve springs. The camshaft
lobe changes rotary motion (camshaft) to linear motion (valves).

69. Inlet and Exhaust valve
Inlet valve - admits the air or mixture of air and fuel into engine cylinder.
Exhaust valve - discharge the product of combustion.

70. Valve actuating mechanisms
The valves used in four stroke engines are operated by two mechanisms.
• Valve mechanism for operating the valve in engine block or straight or side valve
mechanism.
• Valve mechanism for operating the valve in cylinder head or over head valve
mechanism.

71. Side valve actuating mechanisms
• 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.
• 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 tot the combustion chamber.

72. • 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.
Overhead valve actuating mechanisms

73. Variable valve timing
• In internal combustion engines, Variable valve timing (VVT), also known as
Variable valve actuation (VVA), is any mechanism or method that can alter the
shape or timing of a valve lift event within an internal combustion engine.
• VVT allows the lift, duration, or timing (in various combinations) of the intake
and/or exhaust valves to be changed while the engine is in operation. Two-stroke
engine use a power valve system to get similar results to VVT.
• There are many ways in which this can be achieved, ranging from mechanical
devices to electro-hydraulic and cam-less systems.

74. The Variable Valve Timing (VVT) system
includes
• ECM
• OCV
• VVT controller
The ECM optimizes the valve timing
using the VVT system to control the intake
camshaft. The VVT system includes the
ECM, the OCV and the VVT controller.
The ECM sends a target duty-cycle control
signal to the OCV. This control signal
regulates the oil pressure supplied to the
VVT controller. The VVT controller can
advance or retard the intake camshaft.

75. VTEC (Variable Timing Electronic Control) System

76. Performance
Advantages of Variable Valve Engine
0
20
40
60
80
100
120
140
160
0 1000 2000 3000 4000 5000 6000 7000 8000
Engine Speed (rpm)
Brake
Torque
(N*m)
Convential Engine
Varable Valve Engine
It can be seen from the graph the increases in torque across the power range
of the VVT engine.