Overview engine n t k ngan

Topic 2
Engine Overview

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Presented by: Nguyễn Thị Kiều
Ngân
Date: 22/02/2021


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vocabulary

Convert: Chuyển đổi
Operate: Vận hành
Lubrication: Bôi trơn
Camshaft drive belt =

timing belt: Dây đai cam
Sump: Bình chứa dầu
Crankshaft: Trục khuỷu
Connecting rod: Thanh
truyền
Flywheel: Bánh đà
Camshaft: Trục cam
Valve: Xú pắp
Internal combustion: Động
cơ đốt trong
Permit: Giấy phép / Cho
phép

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Various: Đa dạng
Reciprocating: Chủn
đợng qua lại
Motion: Chuyển động
Transmits: Truyền
Thrust: Đẩy
Proper: Thích hợp
Mechanical energy: Năng
lượng cơ học
Toothed belt: Dây đai có
răng
Sprocket: Bánh răng
Impulese: Động lực đẩy
tới
Oil pump: Bơm nhớt
Strainer: Lưới lọc


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Four Stroke engine: Động cơ
4 kì
Classification: Phân loại
Termed: Thời hạn, giới hạn
Suction/intake stroke: Kì nạp
Compression stroke: Kì nén
Combustion stroke: Kì nổ
Exhaust stroke: Kì xa
Spark Ignition (SI) Engine:
Động cơ xăng
Compression Ignition (CI)
Engine: Động cơ dầu
Internal combustion ( IC):
Động cơ đốt trong
Momentum: Quán tính
Injector: Kim phun

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RPM = Revolution per
minute: Vòng/ phút
Economical: Tiết kiệm
Torque peak: Momen
xoắn cực đại
Longevity: Sự bền bỉ, tuổi
thọ cao
Seal: Phốt
Spring: Lò xo
Constant: Không đổi
Turbulence: Hiệu ứng hỗn
loạn
Cylinder head: Nắp quy
lát
Cylinder block: Thân máy


Engine Overview
1.

Introduction

2.

Engine Construction and Functions

3.

Classification and Operating cycle of
internal combustion engines
3.1 Four stroke cycle
3.2 Comparison of SI and CI engines
3.3 Advantage and disadvantage of SI and CI

engines


I. Introduction of engine
The engine is the heart of the automobile. It converts
fuel into the energy that powers the automobile. To
operate, it requires clean air for the fuel, water for
cooling, electricity (which it generates) for igniting the
fuel, and oil for lubrication. A battery and electric starter
get it going.


II. Engine construction
9. Cylinder
Head

8.
Valve

10.Cylinder Block

Sum
p


• Cylinder Head is fitted
on
the top of cylinder block,
which is to seal the
working end of cylinder
and not to permit entry
and exit of gases on
cover head valve of an
engine
• The valve, spark plug,
camshaft etc. are fitted
on it.



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Cylinder Block are
main part of an
engine, which
combustion of fuel
takes place.
All other parts like

piston, connecting
rod, crankshaft, etc.
are bolted on it.




Crankshaft: It’s a shaft which
transmits the power to developed
by the engine to the various of the
vehicle. It is located in the bottom
end of cylinder block. It transmits
the reciprocating motion of piston
into rotary motion which is used
to rotate wheels of the vehicle

• Connecting rod: It connect
piston to the crankshaft and
transmits the motion and
thrust of piston to crankshaft.
The lower end is connected to
the piston and the bigger end
is connected to the crankshaft


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Valves are used to
control the inlet and
exhaust of internal
combustion engine
Two valves are used for
each cylinder for inlet of
air-fuel mixture inside
cylinder and other for
exhaust combustion
gases.
It is fitted in the port at
the cylinder head by use
of strong spring.



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Camshaft is to
control the opening
and closing of valves
at proper timing
It is placed at the top
or at the bottom of
cylinder


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Piston is placed in the
cylinder and transmits thrust
to the connecting rod
It’s free to move and
compresses the air-fuel
mixture and convert the fuel
energy into mechanical
energy which then transmits
to the crankshaft.


The flywheel is a
 heavy
Sump: disc
The
attached
to the
sump contains
end
of
the lubricating
crankshaft.
oil for the It
help
to transmits
engine’s
moving
parts.

the
power
andAto
pipe from
the
smooth
out
the
oil pump draws
individual
up the oilof the
impulses
through
piston
sothe
that
strainer
the
power flows



• Crankshaft drive
belt - A toothed
belt of often called
the timing belt –
drive the camshaft
from a sprocket
mounted on the
end of the

crankshaft. The
camshaft rotates
at half engine
speed


III. CLASSIFICATION OF
INTERNAL COMBUSTION
ENGINES
3.1 Four stroke cycle
A four-stroke (also four-cycle) engine is an internal
combustion (IC) engine in which the piston completes
four separate strokes while turning the crankshaft. A
stroke refers to the full travel of the piston along the
cylinder, in either direction. The four separate strokes are
termed


Operating Cycle

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Otto (For the Gasoline Engine - SI engine)
Diesel (For the Ideal Diesel Engine - CI engine)


Principle of operation of four-stroke
petrol engine
1. Suction/Intake stroke
In this stroke, the piston moves

from TDC to BDC [(Top Dead
Centre – the farthest position of
piston to the crankshaft) to
(Bottom Dead Centre – the
nearest position of piston to the
crankshaft)].
 The piston moves downward
sucking the air-fuel mixture from
the intake valve.
Key points : Intake valve – OPEN
 Exhaust valve – CLOSED
 Crankshaft rotation – 180°



2. Compression Stroke
Here, the piston moves
from BDC to TDC
compressing the air-fuel
mixture. The momentum
of flywheel helps the
piston to move upwards.
Key points : Intake valve – CLOSED
 Exhaust valve – CLOSED
 Crankshaft rotation –
180° (total = 360°)



3.Combustion stroke

The second rotation of
crankshaft has begun as it
completes one full rotation
during compression stroke.
Power stroke begins with the
expansion of air-fuel mixture
ignited with the help of spark
plug. Here, the piston moves
from TDC to BDC. This stroke
produces mechanical work to
rotate the crankshaft.
Key points : Intake valve – CLOSED
 Exhaust valve – CLOSED
 Crankshaft rotation – 180° (total
= 540°)



4.Exhaust stroke
4. Exhaust Stroke : Again the momentum of
flywheel moves the
piston up from BDC to
TDC thereby driving the
exhaust gases outside
through the exhaust
valve.
Key points : Intake valve – CLOSED
 Exhaust valve – OPEN
 Crankshaft rotation –

180°(total = 720°)




Look at the picture of slideshow 13 th
and describe about principle of
operation of four-stroke diesel
engine


3.2 COMPARISON OF CI AND SI
ENGINES


3.3 Advantages and Disadvantages
of SI and CI engine
 Fuel engine SI

Advantage
 These engines have
lower cost.
 They generate high
rpm at low torque.
 It creates less
pollution compare to
CI engines.
 These engines are
light in weight and
required less space

Disadvantages
 SI engines have
low efficiency
compare to CI
engine.
 These engines are
not economical at
high load.
 Higher fuel
consumption.
 Knocking problem


 Diesel engine - CI
Advantage
 Fuel consumption
 Safety – lower flash
point of diesel
 Torque – lower torque
peak and flatter torque
curve
 Reliability and
maintenance – absence
of electrical ignition
 Longevity – build –
lower rpm – fuel
lubricity

Disadvantage

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Engine weight – due to
higher compression
ratio
Cost – mainly due to
increase weight and
strength
Noise


Question
1.

How do inlet & outlet valves open & close
at that particular times of strokes ? ->
Camshaft (The camshaft is connected to crankshaft via
a gear mechanism or meshed with the help of timing
chain. Above animation – A cam on a camshaft
converting rotational motion into oscillatory motion of
valves thereby opening & closing the valves at the
exact times)

2.

Fill the right word

In SI engine, the fuel get into the
combustion chamber at …stroke.
And …stroke if it is by CI engine