This document provides an overview of reciprocating engines used in automobiles. It discusses the key components of both gasoline and diesel engines, including the cylinder, piston, crankshaft, camshaft, valves, and connecting rod. The document then explains the basic four-stroke cycle of intake, compression, power, and exhaust strokes common to gasoline engines. It also summarizes the combustion process and cycle specific to diesel engines which injects fuel into highly compressed hot air. Materials used for different engine components are also provided.
This document provides an overview of reciprocating engines used in automobiles. It discusses the key components of both gasoline and diesel engines, including the cylinder, piston, crankshaft, camshaft, valves, and connecting rod. The document then explains the basic four-stroke cycle of intake, compression, power, and exhaust strokes common to gasoline engines. It also summarizes the combustion process and cycle specific to diesel engines which injects fuel into highly compressed hot air. Materials used for different engine components are also provided.
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Learn about materials used in its Manufacturing and its characteristics and its functons.
This document provides an overview of reciprocating engines used in automobiles. It discusses the key components of both gasoline and diesel engines, including the cylinder, piston, crankshaft, camshaft, valves, and connecting rod. The document then explains the basic four-stroke cycle of intake, compression, power, and exhaust strokes common to gasoline engines. It also summarizes the combustion process and cycle specific to diesel engines which injects fuel into highly compressed hot air. Materials used for different engine components are also provided.
This document provides an overview of reciprocating engines used in automobiles. It discusses the key components of both gasoline and diesel engines, including the cylinder, piston, crankshaft, camshaft, valves, and connecting rod. The document then explains the basic four-stroke cycle of intake, compression, power, and exhaust strokes common to gasoline engines. It also summarizes the combustion process and cycle specific to diesel engines which injects fuel into highly compressed hot air. Materials used for different engine components are also provided.
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AUTOMOTIVE MATERIALS
Prepared By: Mr. Hardik Shah
Syllabus 1. Engines 2. The cylinder 3. The piston & piston ring 4. The camshaft & crankshaft 5. The connecting rod 6. The catalyst
Contents The reciprocating engine Advantages and disadvantages of reciprocating engines Engine components and typical materials Recent trends in engine technology
The reciprocating engine
The reciprocating engine is an engine in which one or more pistons move up and down in cylinders which gives power to crankshaft to rotate. The engine is the heart of a car although it is normally hidden under the bonnet. Another type is rotary engine. Basics of Reciprocating Engines The cylinder which is closed at one end is filled with a mixture of fuel and air. As the crankshaft turns it pushes piston. The piston is forced up and compresses the mixture in the top of the cylinder. The mixture is set alight and, as it burns, it creates a gas pressure on the piston, forcing it down the cylinder.
Air-cooled Reciprocating engine
Constructional details of Reciprocating Engines A cross-section of an air-cooled engine with principal parts is shown in next page.
A. Parts common to both Petrol and Diesel engine: 1. Cylinder, 2. Cylinder head, 3. Piston, 4. Piston rings, 5. Gudgeon pin, 6. Connecting rod, 7. Crankshaft, 8. Crank, 9. Engine bearing, 10. Crank case. 11. Flywheel, 12. Governor, 13. Valves and valve operating mechanism. B. Parts for Petrol engines only: 1. Spark plug, 2. Carburetor, 3. Fuel pump. C. Parts for Diesel engine only : 1. Fuel pump, 2. Injector.
Four Stroke Engine Working of Four Stroke Engines 1. Intake stroke: the intake stroke draws air and fuel into the combustion chamber. The piston descends in the cylinder bore to evacuate the combustion chamber. When the inlet valve opens, atmospheric pressure forces the air-fuel charge into the evacuated chamber. As a result, the combustible mixture of fuel and air fills the chamber. Working of Four Stroke Engines 2. Compression stroke: at the end of the intake stroke, both inlet and exhaust valves are closed. The inertial action of the crankshaft in turn lifts the piston which compresses the mixture. The ratio of the combustion chamber volume before and after compression is called the compression ratio. Typically the value is approximately 9:1 in spark ignition engines and 15:1 in diesel engines.
Working of Four Stroke Engines 3. Power stroke: when the piston ascends and reaches top dead center, an electric current ignites the spark plug and as the mixed gas burns, it expands and builds pressure in the combustion chamber. The resulting pressure pushes the piston down with several tons of force.
Working of Four Stroke Engines 4. Exhaust stroke: during the exhaust stroke, the inlet valve remains closed whilst the exhaust valve opens. The moving piston pushes the burned fumes through the now open exhaust port and another intake stroke starts again.
Salient Features About Engines During one cycle, the piston makes two round trips and the crankshaft revolves twice. The inlet and exhaust valves open and close only once. The ignition plug also sparks only once. A petrol engine, whether four- or two-stroke, is called a spark ignition (SI) engine because it fires with an ignition plug. The four-stroke-cycle engine contains the lubricating oil in the crankcase. The oil lubricates the crankshaft bearings and cools the hot piston
The two-stroke engine is similar to that of the four-stroke-cycle engine in its reciprocating mechanism. It uses the piston-crankshaft mechanism, but requires only one revolution of the crankshaft for a complete power-producing cycle. The two-stroke engine does not use inlet and exhaust valves. The gas exchange is implemented by scavenging and exhaust porthole openings in the bore wall. The upward and downward motion of the piston simultaneously opens and closes these portholes. The air-fuel mixture then goes in or out of the combustion chamber through the portholes. Combustion takes place at every rotation of the crankshaft.
Two-stroke Engines The gas exchange is implemented by scavenging and exhaust porthole openings in the bore wall. The upward and downward motion of the piston simultaneously opens and closes these portholes. The air-fuel mixture then goes in or out of the combustion chamber through the portholes. After spark ignition inside chamber, Combustion takes place at every rotation of the crankshaft.
Working of Two-stroke Engines In the two-stroke engine, the space in the crankcase works as a pre-compression chamber for each successive fuel charge. The fuel and lubricating oil are premixed and introduced into the crankcase, so that the crankcase cannot be used for storing the lubricating oil. When combustion occurs in the cylinder, the combustion pressure compresses the new gas in the crankcase for the next combustion. The burnt gas then exhausts while drawing in new gas. The lubricating oil mixed into the air-fuel mixture also burns Features of Two-stroke Engines Diesel Engine The only difference between diesel engine and a four-stroke gasoline engine is: No sparkplug on Diesel engine. Has a higher compression ratio. (14:1 to 25:1) Better fuel mileage. Diesel Engine Intake Stroke: Piston moves from TDC to BDC creating vacuum in the cylinder Intake valve opens allowing only air to enter the cylinder and exhaust valve remains closed
Diesel Engine Compression Stroke Both valves stay closed Piston moves from BDC to TDC, compressing air to 22:1 Compressing the air to this extent increases the temperature inside the cylinder to above 1000 degree F. Diesel Engine Power Stroke Both valves stay closed When the piston is at the end of compression stroke(TDC) the injector sprays a mist of diesel fuel into the cylinder. When hot air mixes with diesel fuel an explosion takes place in the cylinder. Expanding gases push the piston from TDC to BDC Diesel Engine Exhaust Stroke Piston moves from BDC to TDC Exhaust valve opens and the exhaust gases escape Intake valve remains closed Diesel Engine Four Strokes of Diesel Engine The piston loses speed at the dead-center points where the travelling direction reverses, which gives enough time for combustion and intake as well as for exhaust. The piston ring faces the cylinder bore wall, separated by an oil film. The resulting lubrication generates low friction and high durability. By sealing the gap between the piston and the cylinder, high compression ratio, high heat efficiency and low fuel consumption can be achieved. Advantages of Reciprocating Engine It is difficult to reuse the exhaust heat. The unbalanced inertial force may results in piston slap that can cause noise and vibration. Disadvantages of Reciprocating Engine Engine Components Parts Of An Engine. PISTON SPARK PLUG CAM SHAFT VALVE ROCKER ARM Components and its work Cylinder A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels Gray cast iron, compact graphite cast iron, cast Al alloy
Piston its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod Al-Si-Cu-Mg alloy
Components and its work Piston rings Piston rings provide a sliding seal between the outer edge of the piston and the inner edge of the cylinder.
The rings serve two purposes: They prevent the fuel/air mixture and exhaust in the combustion chamber from leaking into the sump during compression and combustion. They keep oil in the sump from leaking into the combustion area, where it would be burned and lost. Gray cast iron, spheroidized graphite cast iron, alloy cast iron, spring steel and stainless steel Components and its work Connecting rod The connecting rod connects the piston to the crankshaft. It can rotate at both ends so that its angle can change as the piston moves and the crankshaft rotates. Carbon steel, iron base sintered metal, micro-alloyed steel, spheroidized graphite cast iron Crankshaft The crankshaft turns the piston's up and down motion into circular motion just like a crank on a jack-in-the- box does Carbon steel, micro-alloyed steel, Cr-Mo steel and nodular, cast iron Sump The sump surrounds the crankshaft. It contains some amount of oil, which collects in the bottom of the sump (the oil pan).
Components and its work Camshaft Its an internal component of valve train which controls the valve operation timing with pushrod or rocker arms or self controlling lobes. Chilled cast iron, Cr-Mo steel, iron base sintered metal Valve and Valve spring The valve which allows mixture into the cylinder is the inlet valve; the one through which the spent gases escape is the exhaust valve. They are designed to open and close at precise moments, to allow the engine to run efficiently at all speeds.
Valve: Heat-resistive steel, Ti alloy, SiC ceramics. Valve spring: Spring steel, music wire Valve Seat: Iron base sintered metal, cast iron Components and its work Exhaust Manifold The exhaust manifold is the first part of your vehicles exhaust system. It is connected to your vehicles engine and collects your engines emissions. The exhaust manifold receives the air/fuel mixture from the multiple cylinders in your vehicles engine, it completely burns any unused or incomplete burnt gases using its very high temperature. Components and its work Exhaust Manifold The manifold also houses the first oxygen sensor in your exhaust system to inspect the amount of oxygen entering the system. Once the amount of gas in one place completely burnt, the manifold sends the emissions into the rest of the exhaust system.
High-Si cast iron, niresist cast iron, cast stainless steel,stainless steel tube and sheet Components and its work Engine Bearings Bearing is a device supporting a mechanical element and providing its movement relatively to another element with a minimum power loss.
Main crankshaft bearings It support the crankshaft and help it rotate under inertia forces generated by the parts of the shaft and oscillating forces transmitted by the connecting rods. Main bearings are mounted in the crankcase Connecting rod bearings provide rotating motion of the crank pin within the connecting rod, which transmits cycling loads applied to the piston. Connecting rod bearings are mounted in the Big end of the connecting rod. Camshaft bearings It support camshaft and provide its rotation. Al-Si-Sn and Cu-Pb alloys Recent trends in engine technology 1. The multi-valve engine was previously limited to sports cars and motorcycles. To obtain higher output power, the number of valves used in car engines has increased. 2. The multi-cylinder engine has become more widespread. It has a smoother rotation to decrease noise and vibration. 3. Three-way catalyst (Pt-Pd-Rh alloy) technology, using O2 and knock sensors, has decreased the three components CO, HC, and NOx in the exhaust gas, to decrease environmental pollution. 4. The variable valve system has decreased fuel consumption. 5. Decreased inertial weight and electronic control have given improved engine performance. 6. Hybrid systems including an electric motor have reduced fuel consumption.
Part name Material Cylinder block Gray cast iron, compact graphite cast iron, cast Al alloy Piston Al-Si-Cu-Mg alloy Piston ring Gray cast iron, spheroidized graphite cast iron, alloy cast iron, spring steel and stainless steel Camshaft Chilled cast iron, Cr-Mo steel, iron base sintered metal Valve Heat-resistive steel, Ti alloy, SiC ceramics Valve seat Iron base sintered metal, cast iron Valve spring Spring steel, music wire Piston pin Nodular cast iron, Si-Cr steel, stainless steel Connecting rod Carbon steel, iron base sintered metal, micro-alloyed steel,spheroidized graphite cast iron Crankshaft Carbon steel, micro-alloyed steel, Cr-Mo steel and nodular,cast iron Turbo charger Niresist cast iron, cast stainless steel, superalloy Exhaust manifold High-Si cast iron, niresist cast iron, cast stainless steel,stainless steel tube and sheet Plain bearing Al-Si-Sn and Cu-Pb alloys Catalyst Pt-Pd-Rh alloy The science and technology of materials in automotive engines by Hiroshi Yamagata Automotive Engineering Lightweight, Functional, and Novel Materials by Brian Cantor.
Advance composite materials for automotive applications by Ahmed Elmarakbi