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Topic Engine Overview { Presented by: Nguyễn Thị Kiều Ngân Date: 22/02/2021 • • • • • • • • • • • • 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 đốt Permit: Giấy phép / Cho phép • • • • • • • • • • • • Various: Đa dạng Reciprocating: Chuyển động qua lại Motion: Chuyển động Transmits: Truyền Thrust: Đẩy Proper: Thích hợp Mechanical energy: Năng lượng học Toothed belt: Dây đai có Sprocket: Bánh Impulese: Động lực đẩy tới Oil pump: Bơm nhớt Strainer: Lưới lọc • • • • • • • • • • • • Four Stroke engine: Động 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 xăng Compression Ignition (CI) Engine: Động dầu Internal combustion ( IC): Động đốt Momentum: Quán tính Injector: Kim phun 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 Introduction Engine Construction and Functions 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 Cylinder Head 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 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 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 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 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 Otto (For the Gasoline Engine - SI engine) Diesel (For the Ideal Diesel Engine - CI engine) Principle of operation of four-stroke petrol engine 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° 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 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 Engine weight – due to higher compression ratio Cost – mainly due to increase weight and strength Noise Question How 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) Fill the right word In SI engine, the fuel get into the combustion chamber at …stroke And …stroke if it is by CI engine ... Turbulence: Hiệu ứng hỗn loạn Cylinder head: Nắp quy lát Cylinder block: Thân máy Engine Overview Introduction Engine Construction and Functions Classification and Operating cycle of internal