Main Components of Automobile Engine

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Main components of AutomobileEngine

By: Himanshu SinghM.I.E. 7th sem

Dronacharaya College of Engg.


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Internal combustion engine

Internal combustion engines are most commonly used for mobilepropulsion invehicles and portable machinery. In mobile

equipment, internal combustion is advantageous since it canprovide high power-to-weight ratios together with excellent fuelenergy density. Generally using fossil fuel , these engines haveappeared in transport in almost all vehicles (automobiles, trucks,motorcycles,boats, and in a wide variety ofaircraft andlocomotives).

Where very high power-to-weight ratios are required, internalcombustion engines appear in the form ofgas turbines. Theseapplications includejet aircraft, helicopters, large ships and electricgenerators.


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Different types of I.C. Engines

The I.C. Engines are classified according to there principles ofoperation.

The primary examples are as follows:

Reciprocating : Two Stroke engines

Four Stroke engines

Six Stroke engines

Atkinson Cycle engines


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Rotary : Wankel Engine

Continuous combustion: Gas TurbineJet Engine (Ram jet, Turbo jet etc.)


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Four-stroke internal combustionengines As their name implies, four-stroke internal combustion engines

have four basic steps that repeat with every two revolutions of the

engine: (1) Intake stroke

(2) Compression stroke

(3) Power stroke and

(4) Exhaust stroke


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Intake stroke: The first stroke of the IC engine is also known asthe suction stroke because the piston moves to the maximum

volume position (downward direction in the cylinder). The inletvalve opens as a result of piston movement, and the vaporized fuelmixture enters the combustion chamber. The inlet valve closes atthe end of this stroke.

Compression stroke: In this stroke, both valves are closed andthe piston starts its movement to the minimum volume position(upward direction in the cylinder) and compresses the fuel mixture.During the compression process, pressure, temperature and thedensity of the fuel mixture increases.


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Power stroke: When the piston reaches the minimum volumeposition, the spark plug ignites the fuel mixture and burns. The fuel

produces power that is transmitted to the crank shaft mechanism. Exhaust stroke: In the end of the power stroke, the exhaust valve

opens. During this stroke, the piston starts its movement in theminimum volume position. The open exhaust valve allows theexhaust gases to escape the cylinder. At the end of this stroke, theexhaust valve closes, the inlet valve opens, and the sequence repeatsin the next cycle. Four stroke engines require two revolutions.


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Two-stroke internal combustionengines Engines based on the two-stroke cycle use two strokes (one up, one

down) for every power stroke. Since there are no dedicated intake or

exhaust strokes, alternative methods must be used to scavenge thecylinders. The most common method in spark-ignition two-strokesis to use the downward motion of the piston to pressurize freshcharge in the crankcase, which is then blown through the cylinderthrough ports in the cylinder walls.

Spark-ignition two-strokes are small and light for their poweroutput and mechanically very simple; however, they are alsogenerally less efficient and more polluting than their four-strokecounterparts. In terms of power per cm, a two-stroke engineproduces comparable power to an equivalent four-stroke engine.The advantage of having one power stroke for every 360 of


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crankshaft rotation (compared to 720 in a 4 stroke motor) is balancedby the less complete intake and exhaust and the shorter effective

compression and power strokes. It may be possible for a two stroketo produce more power than an equivalent four stroke, over anarrow range of engine speeds, at the expense of less power at otherspeeds.


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Six-stroke internal combustion engines

The six-stroke engine is a type ofinternal combustion enginebased on the four-stroke engine, but with additional complexity

intended to make it more efficient and reduce emissions. Twodifferent types of six-stroke engine have been developed since the1990s:

In the first approach, the engine captures the heat lost from thefour-stroke Otto cycle or Diesel cycle and uses it to power anadditional power and exhaust stroke of the piston in the samecylinder. Designs use either steam or air as the working fluid for theadditional power stroke.[1] The pistons in this type of six-strokeengine go up and down three times for each injection of fuel. Thereare two power strokes: one with fuel, the other with steam or air.


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The second approach to the six-stroke engine uses a second opposedpiston in each cylinder that moves at half the cyclical rate of the

main piston, thus giving six piston movements per cycle.Functionally, the second piston replaces the valve mechanism of aconventional engine but also increases the compression ratio.


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The Wankel engine

The Wankel engine (rotary engine) does not have piston strokes. Itoperates with the same separation of phases as the four-stroke

engine with the phases taking place in separate locations in theengine. In thermodynamics terms it follows the Otto engine cycle, somay be thought of as a "four-phase" engine. While it is true thatthree power strokes typically occur per rotor revolution due to the3:1 revolution ratio of the rotor to the eccentric shaft, only onepower stroke per shaft revolution actually occurs; this engine

provides three power 'strokes' per revolution per rotor giving it agreater power-to-weight ratio than piston engines. This type ofengine is most notably used in the current Mazda RX-8, the earlierRX-7, and other models.


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Gas turbine

A gas turbine is a rotary machine similar in principle to a steamturbine and it consists of three main components: a compressor, a

combustion chamber, and a turbine. The air after being compressedin the compressor is heated by burning fuel in it. About of theheated air combined with the products of combustion is expandedin a turbine resulting in work output which is used to drive thecompressor. The rest (about ) is available as useful work output.


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Main Components of an I.C. Engine

Combustion Chamber: Internal combustion engines can containany number of combustion chambers (cylinders), with numbers

between one and twelve being common, though as many as 36(Lycomming R-7755) have been used. Having more cylinders in anengine yields two potential benefits: first, the engine can have alarger displacement with smaller individual reciprocating masses,that is, the mass of each piston can be less thus making a smoother-running engine since the engine tends to vibrate as a result of the

pistons moving up and down. Doubling the number of the same sizecylinders will double the torque and power.


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Piston : They are the reciprocating parts of an I.C. Enginewhich are found inside the combustion chambers. Engine are

classified according to the number of piston they have. Dependingupon the power requirements the engines can have up to 16cylinders.The downside to having more pistons is that the enginewill tend to weigh more and generate more internal friction as thegreater number of pistons rub against the inside of their cylinders.

This tends to decrease fuel efficiency and robs the engine of some ofits power.


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SparkPlug: Spark plugs are generally found in petrol driven

i.c. engines. They provide precise timing for the spark to be producedand hence is responsible for combustion.

Carburetor: Simpler reciprocating engines continue to use acarburetor to supply fuel into the cylinder. Although carburetortechnology in automobiles reached a very high degree of sophisticationand precision, from the mid-1980s it lost out on cost and flexibility tofuel injection. Simple forms of carburetor remain in widespread use insmall engines such as lawn mowers and more sophisticated forms are

still used in small motorcycles. Fuel injector: Fuel injection is a system for mixing fuel with air in

an internal combustion engine. It has become the primary fuel deliverysystem used in automotive engines, having almost completely replacedcarburetors in the late 1980s.


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The primary difference between carburetors and fuel injection isthat fuel injection atomizes the fuel by forcibly pumping it through a

small nozzle under high pressure, while a carburetor relies on lowpressure created by intake air rushing through it to add the fuel tothe airstream.

Fuel pump: A fuel pump is a frequently (but not always) essentialcomponent on an i.c. engine device. Many engines (older motorcycleengines in particular) do not require any fuel pump at all, requiringonly gravity to feed fuel from the fuel tank through a line or hose tothe engine. But in non-Gravity feed designs, fuel has to be pumpedfrom the Fuel tanks to the engine and delivered under low pressureto the carburetor or under high pressure to the fuel injection system.


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Fuel injector


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Super chargers:A supercharger is a forced induction systemwhich uses a compressor powered by the shaft of the engine which

forces air through the valves of the engine to achieve higher flow.When these systems are employed the maximum absolute pressureat the inlet valve is typically around 2 times atmospheric pressure ormore.


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Super charger TurbochargerLysholm screw rotors with complex shape of each rotor which must run at high speed

and with close tolerances. This makes this type of supercharger expensive. (This unithas beenblued to show close contact areas.)


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Turbo charger:Aturbocharger, or turbo (colloquialism), is acentrifugal compressor powered by a turbine which is driven by an

engine's exhaust gases. Its benefit lies with the compressorincreasing the pressure of air entering the engine (forced induction)thus resulting in greater performance (for either, or both, power and

efficiency). Oil Filter : Oil filters are placed in the engine's oil system to strain

dirt and abrasive materials out of the oil. The oil filter cannotremove things that dilute the oil, such as gasoline and acids.Removing the solid material does help cut down on the possibility ofacids forming. Removing the "grit" reduces the wear on the engineparts.


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Modern passenger car engines use the "full flow" type of oil filters.With this type of filter, all of the oil passes through the filter before

it reaches the engine bearings. If a filter becomes clogged, a bypassvalve allows oil to continue to reach the bearings. The most commontype of oil filter is a cartridge type. Oil filters are disposable; atprescribed intervals, this filter is removed, replaced and thrownaway. Most states now require that oil filters be drained completelybefore disposal, which adds to the cost of an oil change, but helps to

reduce pollution


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Crankshaft: The crankshaft, sometimes casually abbreviatedto crank, is the part of an enginewhich

translates reciprocating linear piston motion into rotation. Toconvert the reciprocating motion into rotation, the crankshaft has"crank throws" or "crankpins", additional bearing surfaces whoseaxis is offset from that of the crank, to which the "big ends" of

the connecting rods from each cylinder attach.

Flywheel:


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Flywheel: The flywheel is a disk or wheel attached to the crank,forming an inertial mass that stores rotational energy. In engines

with only a single cylinder the flywheel is essential to carry energyover from the power stroke into a subsequent compression stroke.Flywheels are present in most reciprocating engines to smooth outthe power delivery over each rotation of the crank and in mostautomotive engines also mount a gear ring for a starter. Therotational inertia of the flywheel also allows a much slower

minimum unloaded speed and also improves the smoothness at idle.The flywheel may also perform a part of the balancing of the systemand so by itself be out of balance, although most engines will use aneutral balance for the flywheel, enabling it to be balanced in aseparate operation. The flywheel is also used as a mounting for the

clutch or a torque converter in most automotive applications.


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Flywheel


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An exhaust system is usuallytubing used to guide reactionexhaust gases away from a controlled combustion inside an engine

or stove. The entire system conveys burnt gases from the engine andincludes one or more exhaust pipes. Depending on the overallsystem design, the exhaust gas may flow through one or more of:

Cylinder head and exhaust manifold

Aturbocharger to increase engine power.

Acatalytic converter to reduce air pollution.

Amuffler (North America) / silencer (Europe), to reduce noise.


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Thank you

Documents

Main Components of Automobile Engine