BỘ GIAO THÔNG VẬN TẢI

TRƢỜNG ĐẠI HỌC HÀNG HẢI

KHOA MÁY TÀU BIỂN

BỘ MÔN ĐỘNG LỰC TÀU BIỂN

BÀI GIẢNG

ĐỘNG CƠ ĐỐT TRONG 1

TÊN HỌC PHẦN ĐỘNG CƠ ĐỐT TRONG 1

MÃ HỌC PHẦN 12101

TRÌNH ĐỘ ĐÀO TẠO ĐẠI HỌC CHÍNH QUY

DÙNG CHO SINH VIÊN NGÀNH KHAI THÁC MÁY TÀU BIỂN

HẢI PHÒNG 2009

2

MỤC LỤC

STT NỘI DUNG TRANG

CONSTRUCTION OF DIESEL ENGINES

1 Operational principle of diesel engines

1.1 The history of developments of diesel engines 7

1.2 Basic definitions, that used for a diesel engine 8

1.3 Operational principle of 4-stroke diesel engines 10

1.4 Operational principle of 2-stroke diesel engines 11

1.5 Comparison between 4-stroke and 2-stroke diesel engines 13

1.6 Timing diagram of gas exchange phases of diesel engines 13

1.7 Classification of internal combustion engines 15

Review questions 17

2 Static parts construction of diessel engines

2.1 Bedplates 18

2.2 Main bearings 20

2.3 Engine frames (frameworks) 24

2.4 Cylinder blocks and cylinder liners 25

2.5 Cylinder covers 29

Review questions 31

3 Moving parts construction of diesel engines

3.1 Piston groups 32

3.2 Connecting rods 41

3.3 Crankshaft 43

Review questions 47

4 Cơ cấu trao đổi khí

4.1 Chức năng và yêu cầu của cơ cấu trao đổi khí 48

4.2 Sơ đồ cơ cấu trao đổi khí dẫn động cơ giới 49

Câu hỏi ôn tập 52

5 Hệ thống nhiên liệu động cơ diesel

5.1 Chức năng và yêu cầu của hệ thống nhiên liệu 54

5.2 Phân loại hệ thống nhiên liệu 54

5.3 Cung cấp nhiên liệu cho chu trình 57

5.4 Các thiết bị chính của hệ thống nhiên liệu 59

Câu hỏi ôn tập 64

6

Hệ thống bôi trơn

6.1 Giới thiệu chung 66

6.2 Dầu bôi trơn và các thiết bị chính của hệ thống bôi trơn 71

Câu hỏi ôn tập 73

7 Hệ thống làm mát

7.1 Giới thiệu chung 74

7.2 Các hệ thống làm mát động cơ diesel 75

7.3 Các thiết bị chính của hệ thống làm mát 76

Câu hỏi ôn tập 77

8 Hệ thống khởi động và đảo chiều

8.1 Hệ thống khởi động 78

8.2 Hệ thống đảo chiều 83

Câu hỏi ôn tập 84

9 Động cơ diesel thấp tốc cỡ lớn

9.1 Đặc điểm kết cấu 85

3

STT NỘI DUNG TRANG

9.2 Cơ cấu trao đổi khí 89

9.3 Hệ thống cung cấp nhiên liệu 89

Câu hỏi ôn tập 90

Một số đề thi tham khảo 91

Đáp án tham khảo 96

4

YÊU CẦU VÀ NỘI DUNG CHI TIẾT

Tên học phần: Động cơ đốt trong 1 Loại học phần: 2

Bộ môn phụ trách giảng dạy: Động lực tàu biển Khoa phụ trách: MTB

Mã học phần: 12101 Tổng số tín chỉ: 4

TS tiết Lý thuyết Thực hành Tự học Bài tập lớn Đồ án môn học

75 45 30 0 0 0

Điều kiện tiên quyết: Trước khi đăng ký học học phần này, sinh viên phải học và thi

đạt các học phần sau: Nguyên lý máy; Chi tiết máy; Nhiệt kỹ thuật.

Mục tiêu của học phần: Cung cấp cho sinh viên kiến thức về kết cấu cơ bản động cơ

diesel tàu thủy, các hệ thống phục vụ cho động cơ diesel, kỹ năng khai thác động cơ diesel

cũng như các hệ thống phục vụ của nó.

Nội dung chủ yếu:

- Nguyên lý hoạt động của động cơ diesel;

- Kết cấu của động cơ diesel;

- Cơ cấp phân phối khí;

- Các hệ thống phục vụ động cơ diesel và kỹ năng khai thác chúng.

5

Nội dung chi tiết:

NỘI DUNG

PHÂN PHỐI THỜI GIAN (tiết)

Lý

thuyết

Thực

hành

Bài tập

lớn

Tổng

số

CONSTRUCTION OF DIESEL ENGINES 45 30 75

Chapter 1. Operational principle of diesel engines 6.0 6.0

1.1 The history of developments of diesel engines 0.5

1.2 Basic definitions, that used for a diesel engine 0.5

1.3 Operational principle of 4-stroke diesel engines 1.5

1.4 Operational principle of 2-stroke diesel engines 1.0

1.5 Comparison between 4-stroke and 2-stroke diesel

engines

0.5

1.6 Timing diagram of gas exchange phases of diesel

engines

1.0

1.7 Classification of internal combustion engines 1.0

Chapter 2. Static parts construction of diessel engines 4.0 5.0 9.0

2.1 Bedplates 0.5

2.2 Main bearings 1.0

2.3 Engine frames (frameworks) 0.5

2.4 Cylinder blocks and cylinder liners 1.5

2.5 Cylinder covers 0.5

Chapter 3. Moving parts construction of diesel engines 5.0 5.0 10.0

3.1 Piston groups 3.0

3.2 Connecting rods 1.0

3.3 Crankshaft 1.0

Chƣơng 4. Cơ cấu trao đổi khí 4.0 4.0 8.0

4.1 Chức năng và yêu cầu của cơ cấu trao đổi khí 0.5

4.2 Sơ đồ cơ cấu trao đổi khí dẫn động cơ giới 3.5

Chƣơng 5. Hệ thống nhiên liệu động cơ diesel 8.0 5.0 13.0

5.1 Chức năng và yêu cầu của hệ thống nhiên liệu 0.5

5.2 Phân loại hệ thống nhiên liệu 2.0

5.3 Cung cấp nhiên liệu cho chu trình 3.0

5.4 Các thiết bị chính của hệ thống nhiên liệu 2.5

Chƣơng 6. Hệ thống bôi trơn 4.0 4.0 8.0

6.1 Giới thiệu chung 2.0

6.2 Dầu bôi trơn và các thiết bị chính của hệ thống bôi

trơn

2.0

Chƣơng7. Hệ thống làm mát 3.0 4.0 7.0

7.1 Giới thiệu chung 0.5

7.2 Các hệ thống làm mát động cơ diesel 2.0

7.3 Các thiết bị chính của hệ thống làm mát 0.5

Chƣơng 8. Hệ thống khởi động và đảo chiều 5.0 3.0 8.0

8.1 Hệ thống khởi động 3.5

8.2 Hệ thống đảo chiều 1.5

Chƣơng 9. Động cơ diesel thấp tốc cỡ lớn 6.0 6.0

9.1 Đặc điểm kết cấu 2.0

6

NỘI DUNG

PHÂN PHỐI THỜI GIAN (tiết)

Lý

thuyết

Thực

hành

Bài tập

lớn

Tổng

số

9.2 Cơ cấu trao đổi khí 2.0

9.3 Hệ thống cung cấp nhiên liệu 2.0

Tổng số tiết 45 30 75

Nhiệm vụ của sinh viên:

- Sinh viên cần phải tham gia đầy đủ các buổi học trên giảng đường cũng như tại

phòng thực hành, ghi chép nội dung bài giảng và đọc thêm các tài liệu tham khảo của môn

học;

- Hoàn thành báo cáo thực hành đúng hạn.

Tài liệu tham khảo:

1. Nhiều tác giả. Động cơ diesel tàu thuỷ. – Hải Phòng: Khoa Máy, Đại học Hàng hải.

2. Trần Hữu Nghị. Động cơ diesel tàu thuỷ. – Hà Nội: Nhà xuất bản Giao thông vận tải.

3. Фомин Ю.Я., Trần Hữu Nghị. Xác định công suất động cơ diesel tàu thuỷ. – Hà Nội:

Nhà xuất bản Giao thông vận tải,1990.

4. Фомин Ю.Я., Trần Hữu Nghị. Chế độ làm việc của động cơ diesel tàu thuỷ. – Hà Nội:

Nhà xuất bản Giao thông vận tải,1990.

5. David Burghardt M., Kingsley George D. Marine diesels. – New York: Prentice-Hall,

Inc.

6. Internal Combustion engines and its components. No name, no source, no date.

7. Фомин Ю.Я. и др. Судовые двигатели внутреннего сгорания. – Л.:

Судостроение, 1989.

8. Возницкий И.В. Современные судовые среднеоборотные двигатели. – СПб.,

2003.

9. Гаврилов В.С., Камкин С.В., Шмелев В.П. Техническая Эксплуатация Судовых

Дизельных Установок. 1985.

Hình thức và tiêu chuẩn đánh giá sinh viên: Thi viết, thời gian làm bài 60 phút.

Thang điểm: Thang điểm chữ A, B, C, D, E, F.

Điểm đánh giá học phần: Z = 0.3X + 0.7Y

Bài giảng này là tài liệu chính thức và thống nhất của Bộ môn Động lực tàu biển,

Khoa Máy tàu biển và được dùng để giảng dạy cho sinh viên.

Ngày phê duyệt:

Trƣởng Bộ môn: TS. Nguyễn Huy Hào

7

CONSTRUCTION OF DIESEL ENGINES

CHAPTER 1

OPERATIONAL PRINCIPLE OF A DIESEL ENGINE

1.1 THE HISTORY OF DEVELOPMENTS OF DIESEL ENGINES

- In the 19th

century and in the early 20th

century, steam engines were widely used in

the world as propulsion plans for steam ships as well as other industrial branches. The steam

engines are known as external combustion engines.

- In 1860, the first internal combustion engine in the world was invented by Lenuar, a

French engineer. This is a 2-stroke engine, its operation based on burning amount of dynamite

in the engine cylinder. However its efficiency was very low (about 3%), so it was not used in

practice.

- In 1876, German engineer Otto designed a 4-stroke engine. Fuel used for this engine

is gasoline (benzine) that burned by electric spark, so it was called spark-ignition engine or

gasoline engine. This kind of engine after has been widely used in industry and on means of

transport.

- In 1897, German engineer Rudolf Diesel designed a new kind of internal combustion

engine that based on compression-ignition principle, in which fuel burn itself at the end of

compression stroke in the cylinder. Kerosene is used as fuel oil for this engine. This kind of

engine after has been known as diesel engine.

- In 1989, the first industrial diesel engine was constructed at factory Nobel in Russia.

This engine was manufactured on base of Rudolf Diesel’s design. Fuel used for the engine

was petroleum, it had output of 18 kw, specific fuel consumption 0.3 kg/kw.h, lower 30% in

comparison with Rudolf Diesel’s design.

- In1903, Russia launched the first motor ship that named Vandan, this was the first

diesel engine ship in the world. It was equipped three same diesel engines with output of 88

kw, RPM 240, ship’s propeller was driven by electric driving mode.

- From 1911 series of ship that used diesel engine with output of 450 kw is launched.

- Nowadays, diesel engines are widely used for the ships due to following remarkable

advantages:

High efficiency;

Low specific fuel consumption;

Small relative dimensions and weight;

High longevity;

Engine speed is appropriate for propeller revolution range.

8

1.2 BASIC DEFINITIONS THAT USED FOR A DIESEL ENGINE

Figure 1.1 Energy transformation schematic in diesel engines

-

Figure 1.2 Principle diagram of a 4-stroke engine

1 – Crankshaft; 2 – Crank web; 3 – Connecting rod; 4 – Cylinder;

5 – Piston; 6 – Intake valve; 7 – Exhaust valve; 8 – Fuel injection valve;

9 – Intake manifold; 10 – Exhaust manifold; 11 – Cylinder cover.

For a diesel engine, they use the following basic definitions:

1. Working process:

Working process is the entire of the changes that happen to working substance in the

cylinder, as well as in the intake and exhaust systems of the engine.

Working process consist of separate parts, they succeed each other in a certain order

and iterate cyclically.

2. Working cycle:

Working cycle is the entire of the processes that take place in the engine cylinder in a

cycle.

Fuel

Diesel engine

Propeller

11

9

3. Four-stroke and two-stroke engines:

- Four-stroke engine: 4-stroke engine is that needs 4 strokes of the piston (correspond

with 2 revolutions of the crankshaft) to complete the working cycle.

- Two-stroke engine: 2-stroke engine is that needs 2 strokes of the piston (correspond

with one revolution of the crankshaft) to complete the working cycle.

4. Stroke cycle:

Stroke is a part of the working cycle that takes place in the interval between two

positions of the piston at TDC (Top Dead Center) and BDC (Bottom Dead Center).

5. Dead centers:

Dead centers of the piston are points or positions of the piston in the cylinder, at which

the piston changes moving direction.

- TDC: TDC is position of the piston in the cylinder, at which distance between the top

of the piston and center line of the crankshaft is longest;

- BDC: BDC is position of the piston in the cylinder, at which distance between the

top of the piston and center line of the crankshaft is shortest.

6. Piston stroke S:

Piston stroke is distance between 2 dead centers. Piston stroke is signed by letter S.

7. Clearance volume Vc:

Clearance volume (or combustion chamber volume) is the smallest volume of the

cylinder that limited by space between the piston top, cylinder wall and cylinder cover, when

the piston located at the TDC.

8. Total volume Va:

Total volume (maximum volume) is the volume of the cylinder, when the piston

located at the BDC. (Vmax = Va).

9. Working volume (stroke volume) Vs.

It is the volume of the cylinder that drawn by piston top, when piston moves between

two dead centers.

Vs = Vmax – Vc = D2S/4

10. Compression ratio :

It is ratio between the total volume of the cylinder and the clearance volume.

= Vmax/Vc = (Vc + Vs)/Vc = 1 + Vs/Vc.

10

1.3 OPERATIONAL PRINCIPLE OF 4-STROKE DIESEL ENGINES

Figure 1.3 Operational principle of 4-stroke diesel engine

1 – Suction stroke

The suction stroke is begun when the piston moves down from the TDC to the BDC,

at that time the intake valve has been opened; the exhaust valve is being closed. Fresh air

from the air intake manifold is charged into the cylinder due to difference of pressures

between the intake port and the cylinder. When the piston reaches to the BDC, all of the

cylinder volume is fully charged by fresh air, in which exists a little amount of combustion

gases in the cylinder from previous working cycle, these gases are called residue gases.

The suction stroke finishes when the piston reaches to the BDC.

2 – Compression stroke

The compression stroke takes place when the piston is moving up from the BDC to the

TDC. At that time, both the intake and exhaust valves are being closed; the cylinder volume is

decreased while the pressure of the working substance in the cylinder is gradually increased,

because of this, the temperature of the working substance in the cylinder is gradually

increased also.

The compression stroke spends engine work (in the other word, compression work is

negative), the work serves for the compression stroke is supplied from the engine flywheel.

At the end of the compression stroke, when the piston goes up nearly the TDC, the

fuel oil is injected in the form of a fine mist into the cylinder by the fuel injection valve. Due

to the high pressure and swirling movement of airflow, the fuel oil when spraying into the

cylinder is atomized and distributed over the combustion chamber. Because of high

temperature of the compressed air in the combustion chamber, the fuel oil vapors and ignites

itself.

3 – Ignition-expansion stroke

The ignition-expansion stroke happens when the piston is moving down from the TDC

to the BDC. At the beginning of the ignition stroke, the fuel oil is being still continuously

injected into the cylinder. At that time, the temperature of the combustion chamber is very

high, because of this the injected fuel oil at this moment rapidly vapors and ignites. The

11

ignition process is divided into 2 phases: the former is the isochoric phase (equal volume

phase) with 40% of the supplied fuel oil; the latter is the isobaric phase.

The ignition of the fuel oil in the cylinder rapidly takes place and it is the same

explosion. Because the fuel oil burns in the small volume of the cylinder, pressure of the

combustion gases highly increases. Then, the combustion gases expand and push the piston

downward to turn the crankshaft. This is the work producible stroke of the engines.

4 – Exhaust stroke

The exhaust stroke takes place when the piston is moving up from the BDC to the

TDC. At that time the exhaust valve has been opened while the intake valve is being closed.

In the early of the exhaust stroke, the combustion gases escape from the combustion chamber

due to difference of pressure between the combustion chamber and the exhaust manifold.

After that, the combustion gases are discharged out by movement of the piston. When

finishing the exhaust stroke, in the combustion chamber remain amount of the residue gases

with the pressure Pr higher than the ambient pressure Po. Thus, the exhaust stroke is carried

out to scavenge the combustion chamber clean before continuing the new working circle.

Figure 1.4 The working cycle of a non-supercharged 4-stroke diesel engine

1.4 OPERATIONAL PRINCIPLE OF 2-STROKE DIESEL ENGINES

1 – First stroke

The first stroke takes place when the piston is moving up from the BDC to the TDC,

the scavenging and exhaust ports are gradually being closed. Firstly, the scavenging ports are

fully closed while the exhaust ports still open, so amount of the fresh air in the cylinder is

discharged out through the exhaust ports (this is called loss phase of the fresh air). The

compression process is begun when the piston is moving up and fully closed the scavenging

and exhaust ports. The piston continues go up to carry out the compression process, the

temperature and the pressure in the cylinder is gradually increased. At the end of the

compression process, when the piston nearly reaches to the TDC, the air temperature in the

cylinder is about 250 ~ 300o higher than the spontaneous combustion temperature. At that

time the fuel oil is injected in the form of a fine mist into the combustion chamber. In the high

temperature condition the fuel oil vapors, mixes together with air in the combustion chamber

and ignites itself. Then, the combustion gases with the high pressure expand and push the

piston downward to turn the crankshaft.

12

Figure 1.5 Principle diagram of a 2-stroke engine

1 – piston; 2 – Scavenging port; 3 – Intake manifold; 4 – Cylinder;

5 – Cylinder cover; 6 – Fuel injection valve; 7 – Exhaust manifold; 8 – Exhaust port

2 – Second stroke

In the second stroke, the piston is moving down from the TDC to carry out the

expansion process. At the end of this process, when the piston opens the exhaust ports, the

combustion gases escape from the cylinder because the pressure in the cylinder is higher than

the pressure in the exhaust manifold. This is free discharge phase.

The piston is continuing go down to the BDC, the pressure in the cylinder is quickly

decreased. When the piston opens the scavenging ports (inlet or intake ports), supercharged

air with the high pressure (higher than the environment pressure) from the intake manifold

blows into the cylinder to force out the remaining combustion gases and to fill up the cylinder

by fresh air. This is called forced discharge phase. When the piston is in the BDC, the opening

section of the scavenging and exhaust ports is maximal. And then, the piston continues go up

again to make a new working circle.

Thus, in the 2-stroke diesel engines the fresh air has to compress to the pressure,

which is higher than the environment pressure to carry out the gas exchange process.

Figure 1.6 The working cycle of a 2-stroke diesel engine

13

1.5 COMPARISON THE 2-STROKE WITH THE 4-STROKE ENGINES

1 – In comparison with the 4-stroke diesel engine, which have the same basic

dimensions (diameter of the cylinder D, stroke of the piston S, revolution speed of the

crankshaft RPM), the 2-stroke engine has a output of about 1.6 ~ 1.8 times higher than the 4-

stroke engine;

2 – Rotating moment of the 2-stroke engines is more even than the 4-stroke engines;

3 – Accelerating ability of the 2-stroke engines is better than the 4-stroke engines;

4 – Exhaust gases temperature of the 2-stroke engines is lower than the 4-stroke

engines;

5 – The gas exchange process of the 2-stroke engines is less perfect than the 4-stroke

engines;

6 – The supercharging for the 2-stroke engines is more difficult than the 4-stroke

engines;

7 – The crankshaft angle that corresponds to the ignition-expansion process in the 2-

stroke engines is smaller than the 4-stroke engines;

8 – The selection and the adjustment of the valve timing in the 2-stroke engines is

more difficult than the 4-stroke engines;

1.6 TIMING DIAGRAM OF THE GAS EXCHANGE PHASES

1.6.1 The timing diagram of the gas exchange phases of the 4-stroke diesel engines

Figure 1.7 The timing diagram of a 4-stroke diesel engine

According to the figure 1.7:

N1: The opening moment of the intake valve;

N2: The closing moment of the intake valve;

O

N1

F1

TD

C

BDC

F2

X2

X1

N2

A

C

B E

14

F1: The beginning of the fuel injection;

F2: The ending of the fuel injection;

X1: The opening moment of the exhaust valve;

X2: The closing moment of the exhaust valve;

angle N1OC = 1: The early opening angle of the intake valve before the TDC

(advanced opening angle);

angle N2OA = 2: The late closing angle of the intake valve after the BDC (delay

closing angle);

angle F1OC = s: The early fuel injection angle of the fuel injection pump be fore the

TDC;

angle F2OC = kt: The ending angle of the fuel injection after the TDC;

angle X1OA = 1: The early opening angle of the exhaust valve before the BDC;

angle X2OC = 2: The late closing angle of the exhaust valve after the TDC;

angle N1OX2: The overlap angle of the intake and exhaust valves;

N1 C A N2: The suction process;

N2 B F1: The compression process;

F1 C E X1: The ignition and expansion process;

X1 A B X2: The exhaust process;

Some definitions:

- The early opening angle of the intake valve:

- The late closing angle of the intake valve:

- The early opening angle of the exhaust valve:

- The late closing angle of the exhaust valve:

- The early injection angle:

Purpose of early opening and late closing the valves, as well early injection of fuel

1.6.2. The timing diagram of the gas exchange phases of the 2-stroke diesel engines

Figure 1.8 The timing diagram of a return flow scavenging diesel engine

O

F1

TDC

BDC

F2

d

a

c

d’

b’ b

15

According to the figure 1.8:

b: The opening moment of the exhaust ports;

d: The opening moment of the scavenging ports (inlet ports);

d’: The closing moment of the scavenging ports;

b’: The closing moment of the exhaust ports;

F1 c F2 b: The ignition and expansion process;

b d: The free discharge phase;

d d’: The scavenging (forced discharge) and air charge phases;

d’ b’: The loss phase of the fresh air.

1.7 CLASSIFICATION OF THE INTERNAL COMBUSTION ENGINES

1 – Classify by operational principle:

+ 4-stroke engines

+ 2-stroke engines

2 – Classify by kinds of using fuel oil:

+ Engines with gaseous fuel

+ Engines with light liquid fuel (Petrol, kerosene)

+ Engines with diesel oil (DO)

+ Engines with heavy fuel oil (FO or HFO)

+ Engines with mixing fuel oil (Gas and liquid fuel or DO and FO)

3 – Classify by kinds of combustion chambers:

+ Engines with direct injection chamber

+ Engines with pre-combustion chamber

+ Engines with swirl combustion chamber (vortex combustion chamber)

+ Engines with the combustion chamber in the piston crown

4 – Classify by the working circle:

+ Engines with isochoric circle (Gasoline engines, gas engines, in which the fuel is

burned by electric spark)

+ Engines with isobaric circle (Engines, in which the fuel oil is supplied by

compressed air. This kind of engines nowadays is rarely used)

+ Engines with combining circle (Diesel engines)

5 – Classify by methods of air charge:

+ Non-supercharged engines (Engines, in which the pressure at the intake port is equal

to the environment pressure, Po)

16

+ Supercharged engines (the pressure at the intake port Ps is higher than the pressure

of the environment Po)

6 – Classify by the numbers of the cylinders:

+ Engines with only one cylinder

+ Engines with many cylinders

7 – Classify by the arrangement of the cylinders:

+ Engines with the cylinders in the vertical line

+ Engines with the cylinders in the horizontal line

+ Engines with two lines of the cylinders in the V-shape

+ Engines with many (5) lines of the cylinders in the star-shape

+ Engines with the opposed pistons (figure 1.9)

Figure 1.9 Principle diagram of a opposed pistons engine

8 – Classify by the reversibility of the crankshaft:

+ Reversible engines

+ Irreversible (non-reversible) engines

9 – Classify by the action of the piston:

+ Single action engines

+ Double action engines

10 – Classify by the speed (n – revolution per minute) of the engines:

+ Low speed engines: n 240 rpm (rev/min)

+ Medium speed engines: 240 n 750 rpm (rev/min)

+ High speed engines: n 750 rpm (rev/min)

11 – Classify by the construction of the crank-connecting rod mechanism:

+ Trunk piston engines: (in which the connecting rod is connected directly with the

piston through the piston pin)

+ Crosshead piston engines (or crosshead engines, in which the connecting rod and the

piston rod are connected to the crosshead, figure 1.10)

17

Figure 1.10 Principle diagram of a crosshead engine

12 – Classify by the stroke length of the piston:

+ Short stroke engines: ratio S/D is about 1,0 ~ 1.5

+ Long stroke engines: ratio S/D = 2.5 ~ 3.0

+ Super long stroke engines: ratio S/D 3.0

Review questions

1. State the basic definitions that used for a diesel engine: working process; working circle;

4-stroke and 2-stroke engines; stroke circle; TDC and BDC; piston stroke; clearance

volume; total volume; working volume; compression ratio.

2. State operational principle of 4-stroke and 2-stroke diesel engines.

3. Compare 4-stroke with 2-stroke diesel engine types.

4. Explain the working circle of 4-stroke diesel and 2-stroke engine on the timing diagram.

5. Represent classification of internal combustion engines.