Automobile Engineering Lecture Notes-1 To Final Year Students By Kiranmedesign Gmail.Com

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1. AUTOMOBILE
ENGINEERING
BY
KIRAN KUMAR.K
Lecturer
Mechanical Engineering Department
College of Engineering and Technology
Eritrea Institute of Technology, Mainefai, Asmara,Eritrea.
e-mail: [email protected]
[email protected]
1

2. CONTENTS
•Working of engine
•Classification of engines
•Engine construction details
•Engine components
•Cooling system
–Air cooling system
–Water cooling system
Bearings
2

3. ENGINE
3

4. Petrol Engine Operation
A Petrol engines operation sequence is as follows:
Stroke 1 (intake) –air & fuel enter cylinder
Stroke 2 (compression) –air & fuel are
compressed
Stroke 3 (power) –spark plug fires, ignites fuel.
Stroke 4 (exhaust) –burnt gases are expelled from
the engine
4

5. ENGINE
5

6. CLASSIFICATION OF ENGINES
•Number of cylinders
•Arrangement of cylinders
–Inline, V type, Opposed piston, Opposed cylinder, Radial type
•Valve arrangement
–L head, T head, I head, F head
•Type of cooling
–Water cooling , Air cooling
•Number of cycles
–Two stroke, Four stroke
•Type of fuel
–Petrol, Diesel, LPG, CNG
6

7. Engine Construction
7
Inline
•Here all the cylinders of the engine
are in a straight line. This is the most
popular type of engine in India.
•The Engine is usually placed
vertically or in some rarer cases kept
leaning at an angle.

8. Engine Construction
8
V
The cylinders arranged in two banks
connected to the same crankshaft.
Different angles are used between the
cylinder banks.
V engines offer the car to have more
cylinders with a shorter bonnet length, giving
better road visibility.
V engines are well balanced, smooth and
quiet in operation.
Assures relatively even distribution of air fuel
mixtures to all cylinders
Shorter but lighter and more rigid engine

9. Engine Construction
9
Flat/Horizontally Opposed/Boxer
A Boxer engine is a ‘V’ engine with
an angle between the cylinder
banks of 180 Deg.
The pistons look like a boxers fists
going back and forth hence the
‘boxer’ name.
These engines offer some benefits,
but are complicated in design and
expensive to produce & maintain,
hence are not widely used.

10. Engine Construction
10
Inline
Here all the cylinders of the
engine are in a straight line.
This is the most popular type
of engine in India.
The Engine is usually placed
vertically or in some rarer
cases kept leaning at an angle.
V
The cylinders arranged in two banks
connected to the same crankshaft.
Different angles are used between the
cylinder banks.
V engines offer the car to have more
cylinders with a shorter bonnet
length, giving better road visibility.
V engines are well balanced, smooth
and quiet in operation.
Flat/Horizontally Opposed/Boxer
A Boxer engine is a ‘V’ engine with
an angle between the cylinder banks
of 180 Deg. The pistons look like a
boxers fists going back and forth
hence the ‘boxer’ name.
These engines offer some benefits,
but are complicated in design and
expensive to produce & maintain,
hence are not widely used.

11. CLASSIFICATION OF ENGINES
•Number of cylinders
•Arrangement of cylinders
–Inline, V type, Opposed piston, Opposed cylinder, Radial type
•Valve arrangement
–L head, T head, I head, F head
•Type of cooling
–Water cooling , Air cooling
•Number of cycles
–Two stroke, Four stroke
•Type of fuel
–Petrol, Diesel, LPG, CNG
11

12. 12

13. CLASSIFICATION OF ENGINES
•Number of cylinders
•Arrangement of cylinders
–Inline, V type, Opposed piston, Opposed cylinder, Radial type
•Valve arrangement
–L head, T head, I head, F head
•Type of cooling
–Water cooling , Air cooling
•Number of cycles
–Two stroke, Four stroke
•Type of fuel
–Petrol, Diesel, LPG, CNG
13

14. ENGINE –CONSTRUCTIONAL DETAILS
•Cylinder block
•Cylinder head
•Piston
•Piston rings
•Piston pins
•Connecting rod Fig
•Crank shaft
•Cam shaft
•Cam ,Push rod
•Valves
•Fly wheel
14

15. 15

16. SWIFT DIESEL
16

17. 17

18. CYLINDER BLOCK
•Basic frame work of an engine.
•Material : Aluuiviuu, Gray cast irov or irov alloyed ?ith Ni, Cr…
•Block contains cylinder, water jackets, water pump, timing gear,
ignition distributor, valves, fuel pump etc
•Cylinder contains bore liners (iron or steel alloy with good wear resistant)
•Dry liners - Contributes to rigidity ,less heat transfer
•Wet liners - Less rigid, Easy to remove, More heat transfer, Coolant leakage
•
18

19. Engine Cylinder Block
•The engine cylinder block is the basic frame of a liquid-cooled engine, whether
it is the in-line, horizontally opposed, or V-type.
•The cylinder block and crankcase are often cast in one piece that is the
heaviest single piece of metal in the engine.
•In small engines, where weight is an important consideration, the crankcase
may be cast separately.
•In most large diesel engines, such as those used in power plants, the crankcase
is cast separately and is attached to a heavy stationary engine base.
•In practically all automotive and construction equipment, the cylinder block
and crankcase are cast in one piece.
•The cylinders of a liquid-cooled engine are surrounded by jackets through
which the cooling liquid circulates. These jackets are cast integrally with the
cylinder block.
•The cylinders of air-cooled engines have closely spaced fins surrounding the
barrel; these fins provide an increased surface area from which heat can be
dissipated.
•This engine design is in contrast to that of the liquid-cooled engine, which has
a water jacket around its cylinders.
19

20. Cylinder Block Construction
•The cylinder block is cast from gray iron or iron alloyed with other metals such as nickel, chromium,
or molybdenum or aluminum.
•Cylinders are machined by grinding or boring to give them the desired true inner surface. During
normal engine operation, cylinder walls will wear out-of-round, or they may become cracked and
scored if not properly lubricated or cooled.
•Liners (sleeves) made of metal alloys resistant to wear are used in many gasoline engines and
practically all diesel engines to lessen wear.
•The liners are inserted into a hole in the block with either a PRESS FIT or a SLIP FIT. Liners are
further designated as either a WET-TYPE or DRY-TYPE. The wet-type liner comes in direct contact
with the coolant and is sealed at the top by a metallic sealing ring and at the bottom by a rubber
sealing ring. The dry-type liner does not contact the coolant.
•Engine blocks for L-head engines contain the passageways for the valves and valve ports. The lower
part of the block (crankcase) supports the crankshaft (the main bearings and bearing caps) and
provides a place to which the oil pan can be fastened.
•The camshaft is supported in the cylinder block by bushings that fit into machined holes in the
block. On L-head in-line engines, the intake and exhaust manifolds are attached to the side of the
cylinder block. On L-head V-8 engines, the intake manifold is located between the two banks of
cylinders; these engines have two exhaust manifolds, one on the outside of each bank.
20

21. CYLINDER HEAD
•Separate casting bolted to the top of the cylinder block
•Contains the combustion chambers, spark plug, valves, water jackets
•Material :Gray iron or Aluminium alloy
GASKET
•Joint between cylinder block an cylinder head
•Material :Thin sheets of soft metal or
of asbestos and metal
•Squeezes the soft metal thus sealing effectively
21

22. 22

23. CRANK CASE
•Base of the engine
•Supports the crank shaft and cam shaft
•Top half of the crank case is the integral part of cylinder block
•Bottom half of the crank case –Oil pan (Pressed steel or Aluminium)
•Material : Ferrous alloy or semi steel
•
23

24. •The crankcase also has mounting brackets that support the entire engine
on the vehicle frame.
•These brackets are either an integral part of the crankcase or are bolted to
it so that they support the engine at three or four points.
•These points of contact usually are cushioned with rubber that insulates
the frame and the body of the vehicle from engine vibration and therefore
prevents damage to the engine supports and the transmission.
24

25. PISTON
•Acts as a cylindrical plug
•Functions:
–To create vacuum
–To compress air fuel mixture
–To transmit the power
–To expel the exhaust products
•Material
–Aluminium, Cast iron.
–Chrome Nickel
•Head, skirt, land, grooves
•Piston bosses –Reinforced sections of
the piston designed to hold the piston pin
•Piston clearance (0.001 –0.002 inches)
–Small clearance - Piston seizure, oil film
–Large clearance - Piston slap, blow by
–Depends upon (1) Bore of the cylinder
(2) Material
25

26. 26

27. 27

28. PI“TON RING“…..
•To prevent blow by.
•Compression rings -To maintain cylinder pressures
•Oil control rings -Scrape the excess oil from the cylinder
•Material : Cast iron
•Compression rings
–Figure
•
•Figure of joints
•Diameter of rings are slightly larger than the bore
•Staggered joints
28

29. 29

30. PI“TON RING“ …..
•Compression rings
–Action during suction and compression
–Coativgs uaterials such as graphite, phospate for effecti?e ^?ear iv_
–Soak up oil –improve ring lubrication
–prevent scuffing
•Oil control rings
–-Prevents excess of oil going into combustion chamber –functions of oil
–Effect of speed on oil control 30

31. RING EXPANDER
31
•Steel spring in the shape of a wavy or humped ring
•Ring expander makes up for any loss of tension from the reduced
thickness

32. PISTON
•Methods of keeping piston from excessive dimensional change
–Use of special alloy-steel struts or rings
–Horizontal and vertical slots (Fig)
–Heat dams (Fig)
–Cam ground pistons (Fig)
32

33. CONNECTING ROD
•Should be stronger, rigid , lighter (to minimize vibration).
•I section
•Careful matchingof rods
and cap to maintain good
engine balance, equal weight
•Lubrication
•Babbitt bearings
•Bearing linings of steel backed copper
lead or steel backed cadmium
silver
•1 -Cap bolt nut lock washer
•2 - Cap –bolt nut
•3 - Cap
•4 - Rod bearings
•5 - Tongue and groove
•6 - Cap bolt
•7 - Piston pin bearing
•8 - Oil holes
•9 - Oil hole
•10 - Assembled rod
33

34. METHODS OF ATTACHING THE ROD AND PISTON
•Locking the pin to the piston with lock bolt (Fig)
•Locking the connecting rod to piston pin by clamp screw (Fig)
•Lock rings (Fig)
34

35. 35

36. 36

37. 37

38. CRANK SHAFT•Converts the reciprocating motion to the rotary motion.
•Made from steel forging or casting, Stronger
•Length of crank arm decides the stroke
•Drilled oil passages for the flow of oil to the connecting rod brg.
•
38

39. CRANK “HAFT………
•Counter Weights - To balance
–Centrifugal force
–Inertia force
•Heavy bending momentwithout the counter weights
•Speed up and slow down of crankshaft -Flywheel.
39

40. 40

41. VALVE“, CAM “HAFT, PU“H ROD …….
41

42. Camshaft
42
CAMSHAFT

43. 43
L and T type heads

44. Engine- No. of Valves
44
Valve: Valves are provided in the engine to
“breathe” (to take in air and to let out exhaust
gases).
Minimum no of valves required per cylinder are 2
(one for inlet and one for exhaust).
Most Maruti Vehicles have 4 Valves per cylinder
which is Most Advanced Technology.
VALVE

45. 45
•Material :
•Exhaust: Silichrome (unusual resistance to heat)
•Inlet : Nickel –chromium alloy
•Valve tappet clearance (valve lash)
•Valve cooling :
•Importance of valve seating
•Sodium cooled valves

46. 46
•Silent lash rocker arm (Eccentric rocker arm)-I type

47. Engine- No. of Valves
47
Advantage:
More no of valves per cylinder allow the engine to breathe easily.
Benefits :
•Higher Power
•Lesser Pollution
2 valves 3 valves 4 valves
Technology
Old New Latest
Power Developed
Less More Most
Fuel Economy
Less More Most
Emissions
Most More Less

48. Models –Valve Arrangements
48
2 valves 3 valves 4 valves
Ikon Santro XL-7 Grand Vitara
Palio 1.2 Accent 1.5 Gypsy
Petra Diesel Lancer Zen
Getz Esteem
Baleno
WagonR
Accent 1.6
Camry
Indica Xeta

49. Single Over Head Camshaft (SOHC)
In SOHC system all inlet and exhaust valves are
operated by one camshaft which is located in the
cylinder head (Top part of engine) .
This type of arrangement is used in conventional
cars and is superior to the older arrangement
which had push rods to operate the valves.
49

50. 50

51. Engine-Power (BHP)
Brake Horse Power (BHP) is the British unit of measuring power, developed by an
engine.
Power is a measure of how quickly work can be done (moving the car)
Power (BHP) of the engine depends on its torque and engine speed (RPM), more
the torque or more the rpm, greater is the BHP
51
CC : It represents the size of Engine (Combustion Chamber)
E.g. Size of WagonR engine is 1061 cc, 1061 cubic centimeters.
Widest range of engine sizes from 800cc to 2700cc
Engine - Size

52. P-S
•PS is a German term for Metric Horse Power a different unit of measurement of power
developed by the engine.
•1 Metric hp = 1 PS = 0.986 bhp
•100 PS is equivalent to 98.6 bhp.
•In Indian Market all the manufacturers use unit of PS or Metric Horsepower to indicate
engine power.
52

53. Engine- Power to Weight Ratio (PWR)
53
Having more power only is not effective as one must also see the weight
that the power has to carry.
Thus the power to weight ratio must be observed.
Power to Weight Ratio (PWR) :
Power to weight ratio (PWR) is the ratio of bhp (power) to the weight of
the vehicle in tons.
PWR = bhp/ Weight of car in tons.
Higher PWR indicates vehicle’s capability to pull more weight and
accelerate quickly (better pick-up).

54. Comparison of Torque, BHP & PWR (e.g. WagonR)
54
TORQUE BHP PWR
Example
84 N.m@3500 rpm 64 bhp @6200 rpm 77.57
Vehicle
84 N.m indicates
maximum torque
developed
64 bhp indicates
the maximum bhp
developed
77.57 indicates
the pick-up or
acceleration of
the vehicle.
RPM
The rpm indicates
the speed of the
engine at which
maximum torque
is developed
The rpm indicates
the speed of the
engine at which
maximum power is
developed
—

55. BEARINGS
•Bearing = Any thing that supports load
•For supportingand controllingthe motion of rotating, sliding or reciprocating
parts
•Minimize friction, loss of power, heat generation (with the aid of lubrication)
•Types of Friction
–Dry friction : Resistance to relative motion between two dry objects
–Greasy friction : Friction between two solids coated with a thin film of oil
–Viscous friction: Resistance to relative motion between adjacent layers of liquid.
•Types of bearings
–Radial bearing –Load perpendicular to the axis of the shaft
–Thrust bearing - Load parallel to the axis of the shaft
–Radial Thrust bearing –Load parallel and perpendicular to the axis of the shaft
–Slipper bearing (Guide) - Limit the motion to a straight line
55

56. 56
Radial bearing (Plain)
Thrust bearing Radial thrust bearing

57. BEARING “URFACE“ IN AUTOMOBILE“….
57

58. BEARING“ IN AUTOMOBILE“….
•Plain bearing -Friction bearing
•Ball bearing -Anti friction bearing
•Roller bearing -Anti friction bearing
Plain bearing (Radial bearing) –high loads
•Made of dissimilar metals
•Lining of low friction material
•Bearing crush
58

59. 59
•Bearing oil clearance
•About 0.00015 inch –varies with engines
•Optimum oil clearance
•Excessive clearance –high oil consumption, oil starvation
•Less clearance --Metal to metal contact
•Bearing assembly
•Clean
•Free of burrs
•Centralize the cap and bearing

60. BEARING“ IN AUTOMOBILE“….
Ball bearing
•Anti friction bearing
•Substitutes rolling for sliding friction
•Radial thrust ball bearing (Angular contact) (Fig)
•Bearing number
•Needs occasional lubrication to facilitate sliding and protect highly polished
surfaces
60

61. BEARING“ IN AUTOMOBILE“….
Roller bearing
•Straight roller bearing
–Square roller bearing
–Journal roller type
–Needle bearing
•Tapered roller bearing
61

62. 62

63. 63

64. LUBRICATION OF BEARINGS
•To protect the highly finished parts from rust and corrosion
•To reduce bearing temperature
•Keep out the foreign matters
•Lubricant depends upon the operating condition and the location
•
•BEARING REQUIREMENTS
•Load carrying capacity
•Fatique resistance
•Embadability
•Corrosion resistance
•Low wear rate
64

65. 65

66. COOLING SYSTEM
66

67. COOLING SYSTEM
Purpose of cooling
•To keep the engine at its most efficient operating temperature at all driving
condition
•To prevent the deterioration of the lubricating oil (160°C –200°C)
•Decrease in the strength of the material (270°C)
•Results in excessive thermal stresses resulting in cracking
•Hot spot leading to pre ignition and detonation
•Reduction of the volumetric efficiency an hence power
Over cooling problems ?????
•Starting problem
•High corrosion. To avoid condensation of acid, coolant temperature should be
more than 70°C.
67

68. AIR COOLING
•Heat transfer by convection
•Fins to enhance the heat transfer
•Heavily thermal stressed parts should be finned
•Air cooling results in higher temperature and hence larger clearance
•Height of fins control the spacing between the cylinders
•Types of fins
–Length of the fins
–Spacing between the fins
68

69. AIR COOLING…..
Advantages
•No ?ater jacker,puup… -Weight reduction –Small size
•Simpler engine design
•Less sensitive to climatic condition
•Better warm up performance
•Reduced carbon deposits due to higher Temperature
•Easier control
•Can take up some degree of damage
Disadvantages
•Combustion noise is not attenuated
•Lower volumetric efficiency
•High specific output engines can not be air cooled
69

70. Advantages
•Can be used for high sp. Output engine as h of water is high (350 times air)
•High latent heat of water avoids hot spots
•Combustion noise is attenuated
•High volumetric efficiency
•Engine can be installed anywhere
•Disadvantages
•Increase in the weight
•Increase in frontal area increases air resistance
•Requires more maintenance
•Sensitive to climatic condition –Ethylene glycol & Water solution _ Deposits
•Power absorption by the water pump
•Poor warm up performance-greater wear
70

71. TYPE OF COOLING SYSTEM
•Thermosyphon cooling
•Forced cooling system
•Cooling with thermostat regulator
•Pressurized water cooling
71

72. THERMOSYPHON COOLING
•Cooling depends only on temperature and independent of speed
•Circulation starts only after engine becomes hot
•Accumulation of scales
72

73. FORCED OR PUMP COOLING SYSTEM
•Cooling is ensured under all conditions of operations
•Circulation stops when engine stops
•Cooling depends of speed –independent of temperature
•Overheating & over cooling –Thermostatic device
73

74. THERMOSTAT COOLING
•Engine warm up quickly after starting
•No method to increase the cooling action
74

75. THERMOSTAT
75
THERMOSTAT WITH DISC VALVE RADIATOR AND BY
PASS FLOW CONTROL

76. TWO STAGE THERMOSTAT CONTROL
76

77. WATER JACKET, WATER PUMP
•Centrifugal pump
•Nonpositive pump
77

78. FAN
•To provide powerful draft of air through the radiator to improveengine
cooling.
•Need for fan drive control??
–Excessive cooling
–Vibration
–Absorption of power
78

79. ELECTRIC MOTOR DRIVEN THERMOSWITCH CONTROLLED FAN
79

80. MECHANICAL CRANK PIN VARIABLE PITCH TEMPERATURE SENSITIVE FAN DRIVE
80

81. PRESSURIZED COOLING SYSTEM
•The boiling point of the coolant is increased by increasing its pressure.
•Radiator cap
•Blow off valve and vacuum valve
81

82. RADIATOR
•To hold large volume of water in close contact with large volume of air to
enhance the heat transfer.
–Increasing the coolant flow rateraises the power required to drive the pump-
offset the increase in the effectiveness
–Increasing the mean temperature difference between coolant and air raises
the heat dissipation capacity
–Increasing the cooling systems operating pressure raises the boiling point of
the coolant
–50 % ethylene glycol reduces the heat dissipation capacity by around (15%)
82

83. RADIATOR
•Two compartments
83

84. RADIATOR CORE
84
•Tube and fin type
•Ribbon –cellular type

85. TEMPERATURE INDICATORS
•Vapour pressure
–Bourdon tube pressure gauge
•Electric indicators
–Bi metal thermostat type
–Balancing coil type
85

86. –Indicator unit (Bourdon tube )
–Indicator bulb
86

87. •Electric indicators
–Bi metal thermostat type
–Balancing coil type
87