This document provides an overview of four-stroke and two-stroke engines. It describes the four strokes of a four-stroke engine: intake, compression, power, and exhaust. It also outlines the two strokes of a two-stroke engine: the intake/combustion stroke and the expansion/exhaust stroke. The document compares key aspects of four-stroke and two-stroke engines such as the number of rotations required to complete a cycle, how power is produced, and design complexity. It provides details on the function and timing of valves and ports during each stroke.
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4 stroke and 2 stroke petrole engne
1. Presentation on Four stroke and Two Stroke
Engine
Muhammad Awais
BSMT-F17-LC-007
Prepared by
Azmeer CH
BSMT-F17-LC-008
Department of Mechanical
University of Sargodha Lahore Campus
9. Four Stroke Engine
There are mainly four storks in 4-stork engine
Suction/Intake Stroke
Compression Stroke
Power Stroke
Exhaust Stroke
10. Suction/Intake Stroke
inlet valve opens
exhaust valve closed
the pressure in the cylinder will
be atmosphere
the piston moves from the TDC
To BDC
the volume in the cylinder
increase
180 degree of crank angle
11. Compression Stroke
inlet valve and exhaust valve
are closed
The piston moves from BDC
to TDC
The charge contained in the
cylinder will be compressed
Pressure and temperature of
charge increases
12. Power Stroke
The inlet valve and exhaust valve
are closed
The piston moves from TDC to
BDC
The engine produces mechanical
work or power
The pressure of hot gases
gradually decreases and volume
increases
13. Exhaust Stroke
The exhaust valve opens and
the inlet valve is closed
The piston moves from BDC
to TDC
During this motion piston
pushes the exhaust gases
Again the inlet valve open
and the new cycle starts
15. INTRODUCTION
In 1878, Dugald-clerk, a British engineer introduced a
cycle
which could be completed in two stroke of piston rather
than four strokes as is the case with the four stroke cycle
engines. the engines using this cycle were called two
stroke cycle engines
In this engine suction and exhaust strokes are eliminated
Here, instead of valves, ports are used. The exhaust gases
are driven out from cylinder by the fresh charge of fuel
entering the cylinder nearly at the end of the working
stroke.
16. Identify 2 stroke engine from outside
Exhaust port in center of cylinder
Small crankcase
17. Two Stroke Engine
There are mainly two storks in 2 stork engine
Suction stroke
Compression stroke
Expansion stroke
Exhaust Stroke
One half cycle of the crank shaft for one stroke in
two stroke engine
18. Strokes name
First stroke (intake +combustion)
Second one is (expansion +exhaust)
19. First Stroke
The piston is moved from
TDC to BDC
Exhaust and transfer port
open and inlet port close
Piston movedTDC to BDC
and burnt gasses exhaust
Crank Shaft rotate 180
degree
20.
21. Second Stroke
Piston moved from BDC to
TDC and compressed fuel
and burn it
Exhaust and transfer port
close and inlet port open
Crank shaft complete 360
degree and complete 2 stroke
and 4 process
22. Compression
4 Stroke Engine 2 Stroke Engine
4 stroke engine completes 2
rotations of crankshaft after
completing one cycle.
Power is produced once every
4 strokes of the piston.
Engine design is a bit
complicated due to valve
mechanism.
2 stroke engine completes 1
rotation of crankshaft after
completing one cycle.
Power is produced once
during 2 strokes of the piston.
2 stroke engine has ports
which makes it's design
simpler.
23. Compression
No need of adding oil or
lubricant to fuel.
Top side of the piston is
flat.
Mixture remains only in
the combustion
chamber.
4 stroke engines are
heavier.
4 stroke engines make
less noise.
Addition of oil is
required.
A bump or protuberance
may be needed on top
side of piston.
Air-fuel mixture enters
through inlet port &
travels to combustion
chamber
2 stroke engines are
lighter
2 stroke engines are
louder comparatively.