1020-Diploma in Mechanical Engineering - 4020340- III Semester - Thermal Engineering I -Unit 3 : Internal Combustion Engines PPT Prepared By… U. ARAVIND, B.E., M.I.S.T.E., LECTURER / MECHANICAL ENGINEERING LAKSHMI AMMAL POLYTECHNIC COLLEGE K.R. NAGAR, KOVILPATTI - 628 503 THOOTHUKUDI DISTRICT, TAMIL NADU Mobile No: 9943244068 Email Id: aravindulaganathanmech@gmail.com aravindmech@lapc.in

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Lakshmi Ammal Polytechnic College
Department of Mechanical Engineering
Subject Code : 4020340
Subject Name : Thermal Engineering I
Year & Semester : II / III
Scheme : N
Unit : 3
U.Aravind
Lect/Mech
LAPC
Kovilpatti
U.Aravind, Lecturer/Mechanical, LAPC, Kovilpatti

2. Contents:
• I.C. Engines
• Classification of I.C. Engines
• Components of I.C. Engines
and Functions, Materials and
Method of Manufacturing
• Four Stroke cycle diesel and
petrol engine
• Two Stroke cycle diesel and
petrol engine
• Fuel supply system
• Ignition system
• Lubrication system
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Heat Engine:
• It Converts Heat Energy into Mechanical Work
• It is classified into two types
I. External Combustion Engine (EC Engine)
• In this type, combustion of fuel takes place outside the
engine
• Ex. Steam Engine, Steam Turbine
II. Internal Combustion Engine (IC Engine)
• In this type, combustion of fuel takes place inside the
engine cylinder
• Ex. Petrol Engine , Diesel Engine
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7. 1. Based on Fuel
Used
Petrol Engine
Diesel Engine
Gas Engine
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8. 2. Based on
method of Ignition
Spark Ignition
(SI) Engine
Compression
Ignition (CI)
Engine
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9. 3. Based on
Number of
Strokes per Cycle
Two Stoke
Engine
Four Stoke
Engine
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10. 4. Based on
Working Cycle
Otto Cycle
Engine
Diesel Cycle
Engine
Dual
Combustion
Cycle Engine
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11. 5. Based on
Number of
Cylinders
Single
Cylinder
Engine
Multi
Cylinder
Engine
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12. 6. Based on
Arrangements of
Cylinders
Horizontal
Engine
Vertical
Engine
Radial Engine
V-Type
Engine
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13. 7. Based on
Arrangements of
Valves
L-head
Engine
I-head
Engine
F-head
Engine
T-head
Engine
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14. 8. Based on
Cooling System
Air Cooled
Engine
Water Cooled
Engine
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15. 9. Based on Speed
Low Speed
Engine
Medium
Speed Engine
High Speed
Engine
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16. 10. Based on
Applications
Marine
Engine
Automobile
Engine
Aero Engine
Stationary
Engine
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Lakshmi Ammal Polytechnic College
Department of Mechanical Engineering
Subject Code : 4020340
Subject Name : Thermal Engineering I
Year & Semester : II / III
Scheme : N
Unit : 3 – Internal Combustion Engines
U.Aravind
Lect/Mech
LAPC
Kovilpatti

29. Valve Timing Diagram
• The Valves in an IC Engines are
assumed to open and close at the dead
centre position of the piston
• But, in actual practice the valves
operates some degree before or after
the dead centers
• The spiral diagram which represents
the opening and closing of the valves is
known as valve timing diagram & It is
drawn for one complete cycle ( two
revolution of crank shaft)
• It is very useful to get best
performance of the engine
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32. IVO 20° Before TDC
IVC 30° After BDC
Ignition 25° Before TDC
EVO 40° Before BDC
EVC 10° After TDC
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35. IVO 18° Before TDC
IVC 30° After BDC
FIB 10° Before TDC
FIC 20° After TDC
EVO 40° Before BDC
EVC 15° After TDC
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36. Port Timing Diagram
• The ports are provided in the two
strokes cycle engines.
• The Circular diagram which
represents the opening and closing
of the valves is known as Port
timing diagram
• Inlet, Transfer and Exhaust ports
open and close at equal angles on
either side of the dead centre
position.
• It is drawn for one complete cycle
(one revolution of crank shaft)
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39. IPO 50° Before TDC
IPC 50° After TDC
TPO 60° Before BDC
TPC 60° After BDC
EPO 70° Before BDC
EPC 70° After BDC
Ignition 20° Before TDC
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42. IPO 50° Before TDC
IPC 50° After TDC
TPO 40° Before BDC
TPC 40° After BDC
EPO 60° Before BDC
EPC 60° After BDC
FIB 10° Before TDC
FIC 15° After TDC
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Lakshmi Ammal Polytechnic College
Department of Mechanical Engineering
Subject Code : 4020340
Subject Name : Thermal Engineering I
Year & Semester : II / III
Scheme : N
Unit : 3
U.Aravind
Lect/Mech
LAPC
Kovilpatti

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• Lubrication
• Purpose of Lubrication
• Properties of Lubricants
• Parts of IC Engine to be lubricated
• Types of Lubricants
• Types of Lubrication system
• Oil Pumps
Contents:

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• In an IC engine, moving parts and rotating
parts rub against each other, Frictional
force is developed.
• Due to this, Heat Generated and the
engine parts wear quickly.
• Also, Power is loss due to friction.
• Lubricants are introduced between
moving parts and rotating parts to reduce
heat loss wear.

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• To reduce friction between the rubbing parts
• To reduce wear and tear of the rubbing parts
• To reduce noise
• To reduce temperature of engine parts
• To reduce power loss due to friction
• To keep engine parts clean
• To absorb shock
• To prevent Corrosion
• To form a good seal between piston and
cylinder
• To increase the life of the parts

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• High Flash point
• High Oil ness
• High Film Strength
• Optimum Viscosity
• High fire point
• High stability
• Non Corrosive
• Low Cost

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51. Types
of
Lubricants
Liquid
Lubricants
SAE Oil
Mineral Oil
Vegetable Oil
Semi Solid
Lubricants
Grease
Solid
Lubricants
Graphite
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• Crank shaft and Crank Shaft
Bearing
• Cam shaft and Cam Shaft Bearing
• Connecting Rod
• Piston Pin
• Piston Ring
• Valve
• Cylinder Walls

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56. Types
of
Lubrication
System Petroil
Lubrication
System
Wet Sump
Lubrication
System
Gravity
Lubrication
System
Splash
Lubrication
System
High Pressure
Lubrication
System
Semi Pressure
Lubrication
System
Dry Sump
Lubrication
System
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• This system is used in light
engines like automobile engines.
• In this method, the lubricating oil
is forced under pressure for
efficient lubrication.
• It consists of oil sump, oil pump,
oil gallery, oil filter, pressure relief
valve, pressure gauges and oil dip
stick.

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•The oil pump (gear pump) is submerged in the
lubricating oil and it is driven by the cam shaft.
•The gear pump supplies oil to the oil gallery
with high pressure through filters.
•From the oil gallery, the oil is distributed under
pressure to the different parts of the engine
through oil tubes.
•Separate oil tubes carry oil for lubricating big
end bearings, timing gears, crank shaft, cam
shaft, valve assembly, etc.
•Oil from the gallery is supplied to the crank
shaft bearing.

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•The oil flows to the connecting rod big end bearing
through the diagonally drilled hole in the crank shaft.
• A through hole is drilled at the centre of the
connecting rod.
• The oil from the big end bearings flows to the small
end bearings through the hole and lubricate it.
• The excess oil is drained back into the oil sump.
•The delivery pressure of the oil is controlled by relief
valve.
•A pressure gauge indicates the oil pressure in the
system.
•An oil dip stick is provided to measure the oil level in
the sump.

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• The function of an oil pump is to
supply lubricating oil under
pressure to the bearings and the
various parts of the engine to be
lubricated.
• It is located inside the crankcase
and submerged in the oil sump.
• It is driven by the camshaft
through a worm or spiral gear.

64. Types of Oil
Pumps
Gear
Pump
Rotor
Pump
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• The purpose of oil filters is to
remove impurities from the oil,
circulating through the engine
lubrication system.
Types of Oil
Filters
By Pass
System
Full Flow
System

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