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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.
BỘ GIAO THÔNG VẬN TẢI TRƯỜNG DẠI HỌC HANG HẢI KHOA MÁY TÀU BIỂN BỘ MÔN ĐỘNG LỰC TÀU BIỂN • • • BÀI GIẢNG ĐỘNG CƠ ĐỐT TRONG 1 TÊN HỌC PHÀN ĐỘNG CƠ ĐÓT TRONG 1 MÃ HỌC PHẦN 12*101 TRÌNH ĐỘ ĐÀO TẠO ĐẠI HỌC CHÍNH QUY DÙNG CHO SINH VIÊN NGÀNH KHAI THÁC MÁY TÀU BIÉN HẢI PHÒNG 2009 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-strokc 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 câu trao đôi khí 4.1 Chức năng và yêu câu của cơ câu trao đôi khí 48 4.2 Sơ đô cơ câu trao đôi khí dân động cơ giới 49 Câu hói ôn tập 52 5 Hệ thông nhiên liệu động CO' diesel 5.1 Chức năng và yêu câu cùa hệ thông nhiên liệu 54 5.2 Phân loại hệ thông nhiên liệu 54 5.3 Cung câp nhiên liệu cho chu trình 57 5.4 Các thiêt bị chính của hệ thông nhiên liệu 59 Câu hỏi ôn tập 64 Hệ thông bôi tron 6 6.1 Giới thiệu chung 66 6.2 Dâu bôi trơn và các thiêt bị chính cúa hệ thông bôi trơn 71 Câu hỏi ôn tập 73 7 Hệ thông làm mát 7.1 Giới thiệu chung 74 7.2 Các hệ thông làm mát động cơ diesel 75 7.3 Các thiêt bị chính cùa hệ thông làm mát 76 Câu hỏi ôn tập 77 8 Hệ thông khỏi động và đảo chiêu 8.1 Hệ thông khởi động 78 8.2 Hệ thông đảo chiêu 83 Câu hỏi ôn tập 84 9 Động cơ diescl thâp tôc cở lớn 9.1 Đặc điêm kêt câu 85 STT NỘI DUNG TRANG 9.2 Cơ câu trao đôi khí 89 9.3 Hệ thông cung càp nhiên liệu 89 Câu hỏi ôn tập 90 Môt sô đê thi tham khảo 91 Đáp án ỉham khảo 96 2 YÊU CẦU VÀ NÔI DUNG CHI TIÉT Tên học phần: Động cơ đốt trong 1 Loại học phần: 2 Bộ môn phụ trách giảng dạv: Động lực tàu biển Khoa phụ trách: MTB Mã học phần: 12101 Tổng số tín chỉ: 4 TS tiêt Lý thuyêt Thưc hành Tư hoc Bài tập lớn Đô án môn hoc 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: Nguycn 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 dicsel tàu thủy, các hệ thống phục vụ cho động cơ dicsel, kỹ năng khai thác động cơ diescl cũng như các hệ thống phục vụ của nó. Nội dung chủ yếu: - Nguyên lý hoạt động cùa động cơ diesel; - Ket cấu của động cơ diesel; - Cơ cấp phân phối khí; - Các hệ thống phục vụ động cơ diesel và kỹ năng khai thác chúng. Nội dung chi tiết: NỘI DUNG PHÂN PHÓI THỜI GIAN (tiết) Lý thuyết Thực hành Bài ỉập 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 Chưoììg 4. Co' câu trao đôi khí 4.0 4.0 8.0 3 4.1 Chức năng và yêu cầu cùa cơ cấu trao đôi khí 0.5 4.2 Sơ đô cơ câu trao đôi khí dân động cơ giới 3.5 Chưoìig 5. Hệ thông nhiên liệu động cơ diesel 8.0 5.0 13.0 5.1 Chức năng và yêu câu của hệ thông nhiên liệu 0.5 5.2 Phân loại hệ thông nhicn liệu 2.0 5.3 Cung câp nhiên liệu cho chu trình 3.0 5.4 Các thiêt bị chính của hệ thông nhiên liệu 2.5 Chưong 6. Hệ thông bôi tron 4.0 4.0 8.0 6.1 Giới thiệu chung 2.0 6.2 Dâu bôi tron và các thiêt bị chính của hệ thông bôi trơn 2.0 Chưoììg7. Hệ thông làm mát 3.0 4.0 7.0 7.1 Giới thiệu chung 0.5 7.2 Các hệ thông làm mát động cơ diesel 2.0 7.3 Các thiết bị chính của hệ thống làm mát 0.5 Chưoìig 8. Hệ thông khỏi động và đảo chiêu 5.0 3.0 8.0 8.1 Hệ thông khởi động 3.5 8.2 Hệ thông đảo chiêu 1.5 Chưoìig 9. Động cơ diesel thâp tôc cõ - lởn 6.0 6.0 9.1 Đặc điêm kêt câu 2.0 NỘI DUNG PHÂN PHỐI THỜI GIAN (tiết) Lý thuyết Thực hành Bài tập lơn Tống số 9.2 Cơ câu trao đôi khí 2.0 9.3 Hệ thông cung câp nhiên liệu 2.0 Tông sô tỉêt 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 đủng hạn. Tài liệu tham khảo: 1. Nhiều tác giả. Động cơ diesel tàu thuỳ. - Hải Phòng: Khoa Máy, Đại học Hàng hái. 2. Trần Hữu Nghị. Động cơ diesel tàu thuỷ. — Hà Nội: Nhà xuất bản Giao thông vận tải. 3. Oomhh K3.ÍỈ., Trân Hữu Nghị. Xác định công suất động cơ diesel tàu thuỳ. - Hà Nội: Nhà xuất bản Giao thông vận tải, 1990. 4. 0OMHH FO H., 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. 0OMHH K).5I. H Ap. Cydoebie deueamejiu eHympeHHeao ceopaHUH. — JL: Cy^ocTpoeHHe, 1989. 8. B03HHIÍKHH H.B. Coepe.uennbie cydoebie cpedueoôopomnbie deueamenu. — CIIÕ., 2003. 9. raBpHJiOB B.C., KaMKHH C.B., LUMejieB B.n. TexHUHecKLiH 3Kcwiyamaụnn Cydoebix ỊỊmenbHbix YcmaHOHOK. 1985. 4 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 biên, Khoa Máy tàu biến và được dùng đế giảng dạy cho sinh viên. Ngày phê duyệt: Truo'ng Bộ môn: TS. Nguyễn Huy Hào CONSTRUCTION OF DIESEL ENGINES CHAPTER 1 OPERATIONAL PRINCIPLE OF A DIESEL ENGINE 1.1 THE HISTORY OF DEVELOPMENTS OF DIESEL ENGINES - In the 19 th century and in the early 20 th 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. - In 1903, 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; 5 High longevity; Engine speed is appropriate for propeller revolution range. 6 1.2 BASIC DEFINITIONS THAT USED FOR A DIESEL ENGINE □ Q„I1D o Diesel engine I - 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; II - 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 ệllll III Propeller Figure 1.2 Principle diagram of a 4-stroke engine Figure 1.1 Energy transformation schematic in diesel engines 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 V c : 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 V a : Total volume (maximum volume) is the volume of the cylinder, when the piston located at the BDC. (V max = V a ). 9. Working volume (stroke volume) V s . It is the volume of the cylinder that drawn by piston top, when piston moves between two dead centers. V s = V ma x-V c = 7tD 2 S/4 10. Compression ratio 8: It is ratio between the total volume of the cylinder and the clearance volume. 6 = V max /v c = (V c + V s )/V c = 1 + v s /v c . 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 1.3 OPERATIONAL PRINCIPLE OF 4-STROKE DIESEL ENGINES 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. Theignition 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 bums 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 P r higher than the ambient pressure P 0 . Thus, the exhaust stroke is carried out to scavenge the combustion chamber clean before continuing the new working circle. 1.4 OPERATIONAL PRINCIPLE OF 2-STROKE DIESEL ENGINES Figure 1.4 The working cycle of a non-supercharged 4-stroke diesel engine 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 [...]... connecting rod and the piston rod are connected to the crosshead, figure 1. 10) 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... 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: N| : The opening moment of the intake valve; N2: The closing moment of the intake valve; F... axial (longitudinal) shifting In this case, the bearing shells are provided with shoulders, which rest on the edge of the journal (figure 2 .10 ) w f 1 & Figure 2.9 Underslung main bearing of the diesel D100 Figure 2 .10 Construction of a stop bearing 2.3 FRAMEWORK 2.3 .1 Framework of large engines with the long piston stroke - The framework consists of separate frames with a form of letter A The A frames... intake and exhaust valves (for 4-stroke engines) Each cylinder may have 2 or 4 intake and exhaust valves (figure 2. 21) Figure 2. 21 Cylinder cover sections of 4-stroke engines Figure 2 .19 Types of cylinder liners 32 Figure 2 .18 Cylinder liner with oil holes for lubricating In figure 2. 21 is illustrated construction of the cylinder cover of a 4-stroke diesel engine For high-speed small engines the intake... main bearings are hung on the part of the framework (figure 2 .13 b) It permits to reduce weight of the engine - For the V-shape engines, the stud bolts are used the framework, cylinder block and cylinder cover The bearings are hung on the framework (figure 2 .13 ) the engine lower the to fasten main Figure 2 .13 Framework of V-shape engines 2.4 2.4 .1 CYLINDER BLOCK AND CYLINDER LINERS Cylinder block - The... engines the cylinder block is arranged the spaces and passages for exhaust gases (figure 2 .15 ) Figure 2 .15 Cylinder block construction of 2-stroke engines - For the low-speed large engines, the cylinder block is normally made of individual units and then they are secured to each other by bolts (figure2 .16 ) Figure 2 .16 Separate cylinder blocks of low-speed large engines 2.4.2 Cylinder liners - Cylinder... environment pressure to carry out the gas exchange process 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... covers Figure 2 .19 Types of cylinder liners 33 Figure 2 .18 Cylinder liner with oil holes for lubricating To seal the combustion chamber, when assembling, between two surfaces of the cylinder cover and liner shoulder must be placed a copper or steel gasket Fastening the covers with cylinder liners must obey regulations of manufacturer Figure 2 .19 Types of cylinder liners 34 Figure 2 .18 Cylinder liner... cylinder liner 7 Describe the construction of the cylinder cover 8 State attentions that must be paid for cooling and assembling cylinder covers Figure 2 .19 Types of cylinder liners 35 CHAPTER 3 MOVING PARTS CONSTRUCTION OF DIESEL ENGINES 3 .1 3 .1. 1 PISTON GROUP Piston a - Duties of the pistons: - To transmit the pressure of the combustion (burned) gases to the connecting rods (in expansion stroke)... liners) Figure 2.4 Main bearing 3 2.2 .1 - 1 - Crankshaft; 2 - Transverse girders of the bedplate; — Bearing shell; 4 — Bearing cap; 5- Bolt Main bearing shells The bearing shell has a form of a cylindrical half Inside of the bearing shells is covered by a thin anti-corrosion layer (white metal or copper-lead alloy, figure 2.5) Figure 2.5 Main bearing shell - 1 — Upper shell; 2— Lower shell The upper . TRƯỜNG DẠI HỌC HANG HẢI KHOA MÁY TÀU BIỂN BỘ MÔN ĐỘNG LỰC TÀU BIỂN • • • BÀI GIẢNG ĐỘNG CƠ ĐỐT TRONG 1 TÊN HỌC PHÀN ĐỘNG CƠ ĐÓT TRONG 1 MÃ HỌC PHẦN 12 *10 1 TRÌNH ĐỘ ĐÀO TẠO ĐẠI HỌC CHÍNH QUY DÙNG CHO. khảo 91 Đáp án ỉham khảo 96 2 YÊU CẦU VÀ NÔI DUNG CHI TIÉT Tên học phần: Động cơ đốt trong 1 Loại học phần: 2 Bộ môn phụ trách giảng dạv: Động lực tàu biển Khoa phụ trách: MTB Mã học phần: 12 1 01. thông khỏi động và đảo chi u 8 .1 Hệ thông khởi động 78 8.2 Hệ thông đảo chi u 83 Câu hỏi ôn tập 84 9 Động cơ diescl thâp tôc cở lớn 9 .1 Đặc điêm kêt câu 85 STT NỘI DUNG TRANG 9.2 Cơ câu trao