Classification of Engines:Type of Fuel used:Petrol EngineDiesel EngineGas EngineCycle of operations:Otto-cycle engineDiesel-cycle engineDual Combustion cycle engine or semi diesel cycle engine

Classification of Engines:No of Strokes per cycle:Four-stroke engineTwo-stroke engineHot spot ignition engineType of Ignition:Spark ignition (SI) engineCompression ignition (CI) engine

Classification of Engines:No of Cylinders:Single-Cylinder EngineTwo-Cylinder EngineThree-Cylinder EngineFour-Cylinder EngineSix-Cylinder EngineEight-Cylinder EngineTwelve- Cylinder EngineSixteen-Cylinder Engine

Classification of Engines:Arrangement of Cylinders:Vertical EngineHorizontal EngineRadial EngineV EngineOpposed Cylinder EngineType of CoolingAir cooled engineWater cooled engine

Classification of Engines:Valve arrangement:L-head EngineI-head EngineF-head EngineT-head Engine

Classification by fuel used (Petrol):It uses petrol for running.Petrol is a hydrocarbon made up of hydrogen and carbon compounds.Air- Mixture is sucked into the cylinder during the suction stroke of the piston.The correct air petrol mixture is obtained from the carburetor.The mixture is compressed during the compression stroke, ignited during the power stroke and the exhaust gases pushed out during the exhaust stroke. Spark plug is fitted at the top of the cylinder which gives spark to ignite the mixture.

Classification by fuel used (Diesel):It uses diesel for runningIt is light , with a low viscosity and high octane number.Only air is sucked into the cylinder during the suction stroke, and compressed to high pressure.Compression ratio is 22:1. Temperature is obtained about 1000F.Diesel oil is injected by an injector at the end of the compression stroke which catch fire and burns due to the high temperature of the compressed air.No separate ignition system is required.

Diesel Engine differs from Petrol Engine:Air and Petrol mixed in carburetor before entering into the cylinder.Air + petrol mixture is compressed and ignited by a separate spark plug.Diesel directly fed into the cylinder by fuel injector.Only air is compressed in the cylinder and the ignition is accomplished by the heat of compression.

Classification by fuel used (Gas):Gas turbine essentially consists of a two sections:A gasifier sectionPower sectionThe fuel used in gas turbine can be gasoline, kerosene or oil.The gasifier section burns the fuel in a burner and delivers the resulting gas to the power section, where it spins the power turbine.The power turbine then turns the vehicle wheels through a series of gears.

Components of Gas turbine:

Figure Showing Flame Holder in Gas Turbine:

Operation of Gas turbine:

Gasifier consists of rotor with a series of blades around the edge.As the rotor rotates, air between the blades is carried around and thrown out by centrifugal force into the burner which increases the air pressure.The fuel is injected in the burner where it burnt and further rises the pressure and the temperature. The high pressure and high temperature gas then passes through the gasifier nozzle diaphragm.A series of stationary blades directs this gas against a series of curved blades.

Operation of Gas turbine:A series of stationary blades directs this gas against a series of curved blades on the outer edge of the gasifier turbine rotor causing it to rotate at high speed.The turbine rotor and the compressor rotor are mounted on the same shaft, thus the compressor also rotates at high speed.This action continues to supply the burner with a sufficient amount of compressed air.This action continues as long as fuel is supplied to the burner.The high speed is reduced by a series of transmission gears before the power is supplied to the vehicle wheels.

Classification by Cycle Operations:Otto cycle or constant volume cycle was introduced by a German scientist Otto in 1876.The engines operating on this are known as Otto cycle engines.The petrol engine operates on this cycle.Diesel cycle or constant pressure cycle was introduced by Dr. Rudolph Diesel in 1897.The engines operating on this cycle is known as Diesel engines.

Classification by Cycle Operations:Dual Cycle or Dual Combustion cycle:In this cycle more time is allowed for the combustion of fuel in diesel engine.The fuel is injected before the end of the compression stroke so that the combustion proceeds partly at constant volume and partly at constant pressure. Such a cycle is known as dual cycle.All diesel engines actually works on this cycle.

Classification by number of strokes per cycle:

Four Stroke Engine:Completes a cycle in four strokes of a piston.Four strokes require two revolutions of the crankshaft.For two revolutions there is a power stroke.Two stroke Engine:Completes a cycle in two strokes of a piston.Two strokes requires one revolution of crankshaft.For every one revolution there is a power stroke.

Classification by Valve arrangement: Engines are classified according to arrangement of the inlet and outlet valves in various positions in the cylinder head or block.These are L, I, F, T head designs.I head design are most commonly used in automobiles.L head design:Inlet and outlet valves are located side by side in the cylinder block.Cylinder head can be removed easily for overhauling.

Classification by Valve arrangement:

Classification by Valve arrangement: I headed design:The inlet and outlet valves are located in the cylinder head.F head design:Usually inlet valve is in the head the exhaust valve is on the block.T head design:It has inlet valves on the one side and the exhaust valve on the other side of the cylinder.

Classification by type of cooling: (Air Cooled)

Mostly used in motorcycles.The cylinders barrels are usually separate and are equipped with metal fins which gives the large radiating surface to increase the rate of cooling.Many air cooled engines are equipped with the metal shrouds which direct the air flow around the cylinders for improved cooling.

Classification by type of cooling: (Water Cooled)Mostly used in buses, trucks and four wheeled vehicles.The engine uses water with an anti freeze compound added to serve as the cooling medium.The water is circulated through the water jets around each of combustion chambers, cylinders, valve seats and valve stems.After passing through these it passes through the radiator where it is cooled by air drawn through the radiator.

Classification by Number and Arrangement of Cylinders:One cylinder engine is used in motor cycles.Max size is 250-300 cc.Two cylinder engine is used in tractors.These can be arranged in three ways inline, opposed and V type.Four cylinders are mostly used in cars, jeeps. six cylinders are used in buses, trucks.

Engine Classification by arrangement of cylinders

Engine ComponentsBy,

Usha Kiran Kumar Sushakiran.sanivada@kluniversity.inKushal Kumar CKushal.chode@kluniversity.inK Someswara Raosomeswararao@kluniversity.in

Basic Components of Engine:Engine BlockCylinder HeadPiston and piston ringsCrankcaseCrankshaftConnecting rodFlywheelValves and its mechanismCamshaftOther Parts spark plug, ignition devices, carburetor, manifolds.

Engine Block:The engine block is the basic support and attaching point for all other engine parts. Engine blocks are made by pouring molten cast iron, steel, or aluminium into moulds. These moulds can be made of sand or die cast.The major parts installed in or on the block are the pistons, crankshaft, camshaft, cylinder heads, and manifolds.

Engine Block:Cast iron has found to be the satisfactory material for cylinder wall material as it has better wearing qualities.In some small engines are plated with chromium very hard metal , to reduce wall wear and to increase their service life.The materials should have low coefficient of thermal expansion and high wear resistance.

Cylinder Head:The top of the cylinder is covered by a separate cast piece know as cylinder head.It is bolted on the top of the cylinder block.The cylinder head contains the combustion chamber for each cylinder and forms the top of the cylinder. Cylinder heads contain the intake and exhaust valves.

Cylinder HeadIt may be removed for cleaning carbon and grinding valves.To retain the compression in the cylinder a flat piece of gasket is placed between the cylinder head and cylinder block.They also contain oil galleries, coolant passages, and openings to allow the flow of intake and exhaust gases. Cylinder heads are made from either cast iron or aluminium

Crankcase:Crankcase is attached to the bottom face of the cylinder block.It acts as the base to the engine.It supports the crankshaft and camshaft in suitable bearings and provides the arms for supporting the engine on the frame.The oil pan and the lower part of the cylinder block together are called the crankcase.

Crankcase:It also functions like housing and it protects the engine parts against dust, water and mud.It stores lubricating oil required for lubricating engine parts.The size of the crankcase should be sufficiently large as it accommodates the revolving crankshaft along with connecting rod.

Gaskets:The gaskets is a piece of soft sheet having similar cuts and holes as it is in the cylinder head and cylinder block so that the gasket placed between the cylinder block and cylinder head does not interfere with the flow of gases or water or bolts passed.

Types of Gaskets:Copper asbestos gasket: asbestos covered on both sides with copper Steel asbestos gasket: asbestos covered on both sides with copper Single sheet rigid or corrugated gasket: only single sheet of copper or lead is used.Stainless steel gasket: Thin sheet of stainless steel is used and it is used in between the cylinder head and cylinder block. Coated with special varnish, which melts and seals when the cylinder is hot.Cork gasket: used where high pressure is not needed. In crankcase it is used.Rubber gasket: Used in place of cork gasket in holes of crankcase

Cylinder Liners:The cylindrical liners are in the form of barrels made of special alloy iron containing silicon ,manganese, nickel and chromium.They are fitted in the engine block to form a engine cylinder.Some times called as cylinder sleeves.

Dry Liner:It is made in the shape of barrel having flange at the top as shown in fig.The flange keeps the liner in the position in the block. The liner should be in prefect contact with the block for effective cooling.It is not in contact with the cooling water and hence known as dry liner. Its thickness ranges from 1.5 mm to 3mm.

Wet Liner:It is so called as the water comes in contact with the liner.Liner is provided with a flange at the top which fits in the grove made in the cylinder block.To stop the leakage of water into crankcase its lower end is sealed with sealing rings or packing rings.Thickness ranges from 3 mm to 6 mm.

Pistons and Piston Rings:Pistons transfer the force of expanding combustion gases to the connecting rods. They are made of aluminium to reduce weight. Most automotive pistons have two compression rings and one oil ring.Compression rings seal in the pressure created during the compression and power strokes.The oil-control ring is installed below the compression rings to prevent excessive oil consumption.

Piston Rings:Piston rings are not completely closed.They are provided with the gap at the ends.This gap allows the ring to fit over the piston and let the ring expands with out breaking.

Connecting Rod:The connecting rods are forged steel rods that connect the piston to the crankshaft. They transfer the force from the piston to the crankshaft. Each connecting rod is connected to a piston by a piston pin. Piston pin is called as gudgeon pin or wrist pin.

Crankshaft:The crankshaft converts the straight-line force from the piston and connecting rod into rotary force. It is attached to the engine block by bearing caps and bearings that surround the crankshaft journal. This design allows the crankshaft to rotate inside of the bearings with minimal friction. The bearing caps are held to the engine block by two, four, or six bolts torqued to specifications.

Flywheel:Aflywheelis a rotating mechanical device that is used to storerotational energy. Flywheels have a significantmoment of inertiaand thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of itsrotational speed. Energy is transferred to a flywheel by applyingtorqueto it, thereby increasing its rotational speed, and hence its stored energy. Conversely, a flywheel releases stored energy by applying torque to a mechanical load, thereby decreasing the flywheel's rotational speed.

Valves and Valve Train:One or more intake valves are used to control the flow of the air into each cylinder. One or more exhaust valves are used to control the flow of exhaust gases out of each cylinder. Valves also seal the cylinder during the compression and power strokes. They are occasionally called mushroom valves due to their resemblance to a mushroom.Intake and exhaust valves are identical in shape, but intake valves are usually larger. Opening and closing of the valves are controlled by the valve train.

Camshaft:The camshaft controls the distance the valves open and the duration of time over which they are open. There is one camshaft lobe for each valve. until the camshaft lobe allows the valve spring to reseat the valve. On overhead camshaft engines, the cam lobes usually push directly on the valve rocker arm.

62065227630 sbh

*1) The compression rings are installed at the top of the piston. A film of oil between the compression ring and cylinder wall sealspressure in the cylinder. This oil film is only about .001q (.0025 mm) thick, but if it is removed, the engine will not develop enough compression to start.2) During the pistons intake stroke, vacuum in the cylinder tries to pull oil from the cylinder wall To reduce oil loss, the oil-controlring scrapes most of the oil from the cylinder wall when the piston is moving down in the cylinder. A small amount ofoil passes by the oil-control ring to seal the compression rings against the cylinder wall.*