Working of four stroke petrol engine.

1. GR0W MORE FACULTY OF DIPLOMA
ENGINEERING
TOPIC NAME :- FOUR STROKE PETROL ENGINE
BRANCH :- MECHANICAL
SEM :- 5th
GROUP MEMBERS
• VASAVA KALPESH
• VASAVA HITESH
• KISHORI PARTH
• SONDARVA TILAK
SUBJECT TEACHER :- PROF. PATEL CHIRAG SIR

2. INTRODUCTION
FOUR STROKE ENGINE
Engine:
An engine is motor which converts chemical energy into mechanical energy.
Fuel/petrol engine:
A petrol engine (known as a gasoline engine in North America) is an internal
combustion engine with spark-ignition, designed to run on petrol (gasoline) and
similar volatile fuels.
Four stroke engine:
A four-stroke engine (also known as four-cycle) is an internal combustion engine
in which the piston completes four separate strokes which comprise a single
thermodynamic cycle. A stroke refers to the full travel of the piston along the
cylinder, in either direction.

3. FOUR STROKE ENGINE
 Four stroke cycle engine s is working at completed four stroke of
the piston or two revaluation of the crank shaft it is called as four
stroke engine
It is two types of valves is presented these are
 Inlet valve
 Exhaust valve
Four stroke petrol engine working at the four types of
stroke
 Suction stroke
 Compression stroke
 Power stroke or expansion stroke
 Exhaust stroke

4. OTTO CYCLE
 In 1862 a German engineer
Nikolaus Augustus Otto began
experimenting with different kinds
of engines.
 His first experiment was conducted
on a 4-stroke engine. 10 years later
he introduced to the world the
Otto engine.
 The 4-stroke engine consists of a 4
stroke cycle better known as the
Otto cycle.

5. SUCTION STROKE
Suction Stroke (Intake): During a
suction stroke the piston moves TDC
to BDC by the engine crankshaft
either by the momentum of flywheel
and or the electric motor or the
starter motor. During this stroke
piston moves downward and creates
a vacuum inside the combustion
chamber. Inlet valve (Intake valve)
opens during this stoke allowing the
air fuel mixture to enter the
combustion chamber. Here the fuel is
petrol mixed with air.

6. COMPRESSION STROKE
Compression Stroke:
During this stroke piston
moves upward BDC to
TDC and compresses the
charge. The heat
produced by the
compression makes more
homogeneous mixture of
air and petrol inside the
cylinder. This heat makes
it easier to burn. During
this stroke both valves
remains closed.

7. POWER OR EXHAUST STROKE
During this stroke the
Piston moves from TDC
to BDC and mixture
under compression is
ignited by the spark
that is produced by a
spark plug. The
expansion of the gases
due to heat of the
combustion creates a
pressure on the piston
and the cylinder walls.
During this stroke
piston moves
downward. Both valves
remain closed during
this stroke.

8. EXHAUST STROKE
During this stroke the inlet valve remains
closed and the exhaust valve remains open.
During this stroke piston moves BDC to TDC
upward and pushes the burnt gases out
through exhaust valve. Only a small amount
of exhaust gases remain in the clearance
space which gets diluted with the fresh
incoming charge during a next suction
stroke. In this type of engine four strokes of
piston are required to complete the cycle.
Four strokes make two revolutions of the
crankshaft. Each alternative revolution of
the crankshaft has one power stroke. A
power stroke consist of above mentioned
cycles.

10. THERMODYNAMIC PROCESS ANALYSIS

11. ADVANTAGES AND DISADVANTAGES OF FOUR
STROKE PETROL ENGINE
ADVANTAGES
•Less fuel consumption.
•Thermal efficiency is more.
•More volumetric efficiency.
•Less wear and tear.
DISADVANTAGES
• More components.
•Separate valve mechanism is required.
• More cost
•More complicated design.

12. LUBRICATION OF FOUR STROKE PETROL
ENGINE
 Four-stroke engines are lubricated by oil held in an oil sump.
The oil is distributed through the engine by splash lubrication or
a pressurized lubrication pump system; these systems may be
used alone or together

13. APPLICATIONS OF FOUR STROKE PETROL
ENGINE
 The four stroke engine used in petrol car, scooters, small
motor powered boats, motorbikes, water spray system, etc.
 This type of engine is an ingenious and practical design that
has powered millions of vehicles. It produces a large amount
of power in efficient and effective manner. It also generally
produces less pollution and lasts longer than a two stroke
engine. The engine was created by Nikolaus Otto in the mid
1800s, and in his honor, it's sometimes known as the Otto
Engine. The four main strokes or steps that make up the cycle
are intake, compression, combustion, and exhaust, which is
sometimes called the Otto cycle.