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Engine- provides the power to drive the ’s . Is motor which converts chemical energy into mechanical energy.

1. Types of Engine:

Internal combustion engine- is an engine in which the combustion of a fuel (normally a fossil fuel) occurs with an oxidizer (usually air) in a combustion chamber.

2- ENGINE 4- STROKE ENGINE

External combustion engine (EC engine) - is a heat engine where an (internal) is heated by combustion in an external source, through the engine wall or a heat exchanger. The fluid then, by expanding and acting on the mechanism of the engine, produces motion and usable work. The fluid is then cooled, compressed and reused (closed cycle), or (less commonly) dumped, and cool fluid pulled in (open cycle air engine).

LOKOMOTIF ENGINE JET ENGINE

Reciprocating engine, also often known as a engine- is a heat engine that uses one or more reciprocating to convert into a rotating motion. This article describes the common features of all types. The main types are: the internal combustion engine, used extensively in motor ; the , the mainstay of the Industrial Revolution; and the niche application Sterling engine.

STIRLING ENGINE STROKE ENGINE 2 STROKE ENGINE

Rotary engine- is essentially a standard Otto cycle engine, but instead of having a fixed block with rotating as with a conventional , the crankshaft remains stationary and the entire cylinder block rotates around it. In the most common form, the crankshaft was fixed solidly to an aircraft frame, and the propeller simply bolted onto the front of the crankcase.

Two-stroke engine- is an internal combustion engine that completes the process cycle in one revolution of the crankshaft (an up stroke and a down stroke of the piston, compared to twice that number for a four-stroke engine). This is accomplished by using the end of the combustion stroke and the beginning of the compression stroke to perform simultaneously the intake and exhaust (or scavenging) functions. In this way, two-stroke engines often provide high specific power, at least in a narrow range of rotational speeds. The functions of some or all of the valves required by a four-stroke engine are usually served in a two-stroke engine by ports that are opened and closed by the motion of the piston(s), greatly reducing the number of moving parts.

Components of Engine:

 Cylinder Block- also called as engine block is the main bottom end structure. Usually it is made up of iron or aluminum.

Function: In the of the cylinder the fresh charge of air-fuel mixture is ignited, compressed by piston.

 Block- contains the cylinders, which are round passageways fitted with pistons.

 Block houses- holds the major mechanical parts of the engine.

 Cylinder head- fits on top of the cylinder block to close off and seal the top of the cylinder. The cylinder head is flat plate of bolted to the top of cylinder block with head in between; Top of head contains rocker arm & push rod to transfer rotational mechanic from the crankshaft to linear mechanic to operate the valves. It is the key to performance of the internal combustion chamber.

 Contains all or most of the combustion chamber.

 Also contains ports through which the air-fuel mixture enters and burned gases exit the cylinder and the bore for the sparkplug.

 Valve train- is a series of parts used to open and close the intake and exhaust ports.

 Valve- is a movable part that opens and closes the ports. Allow for fuel and air to enter the combustion chamber and later let the exhaust out. They remain sealed during the combustion process and only open when required.

 Inlet Valve & Exhaust Valve- Its function is to intake the fresh air-fuel mixture into the cylinder. Exhaust valve- Its function is to exhaust is the burnt gases by the of piston.

 Camshaft- controls the movement of the valves. Camshaft is a part which is used in piston engine to operate valves. It consists of cylindrical rod with cams. The relationship between camshaft rotation & crankshaft rotation is of critical importance.

 Springs- are used to help close the valves.

 Pistons & Piston Rings- is a cylindrical piece of metal that is located inside the cylinder of the engine. Piston is connected to the crankshaft through the , when piston moves downward sucks fresh air-fuel mixture in suction stroke & ignited inside the cylinder due to this high and pressure generated, thus expanded gas force down to piston.

 Piston rings are an open ended ring that fits into a groove or outer diameter of the cylinder. Piston rings have three major functions which are to seal the expansion chamber, support heat transfer & finally, regulate the engine oil consumption.

 Spark Plug- gasoline engines make use of a spark to ignite the fuel and cause a controlled explosion in the engine. The spark plug in these engines supplies the spark that is required to ignite the air and fuel mixture.

 Crankshaft- is the part of an engine which translates the reciprocating linear motion of piston into rotation. To convert the reciprocating motion into rotation, the crankshaft has “ pin”, it typically connects to flywheel, to reduce the pulsation characteristics four stroke cycle.

 Connecting rod and Gudgeon- the connecting rod connects the piston to the crankshaft. As the piston moves up and down due to the controlled explosions, it causes the connecting rod to move. This then cause the crankshaft to move as well as it is connected to the connecting rod, in a circular motion due to the configuration of the piston, connecting rod and crankshaft.

- A small end of connecting rod is connected to the piston and other end is connected to the crankshaft. Its function is to transmit the reciprocating motion of piston to the rotary motion of crankshaft. Gudgeon pin is used to connect the piston & connecting rod.

 Sump- surrounding the crankshaft, the sump contains some amount of oil.

Various Parts of Engine:

• Cylinder Block Cylinder Head

• Inlet valve & Exhaust valve Piston

• Piston Rings Connecting Rod

• Gudgeon Pin Crankshaft

• Crankcase Crank Pin

• Camshaft Spark plug

• Fuel

Classification of Engine:

 Operational Cycles. (4 stroke or 2 stroke)  Number of Cylinders. (3,4,5,6,8,10,12 cylinders)  Cylinder Arrangement. (Flat, inline, V-type)  Valve Train Type. (OHC,OHV, DOHC)  Ignition Type (Spark, Compression)  Fuel Type (gasoline, natural gas, methanol, diesel, propane, fuel cell, electric, hybrid)

2. Internal Combustion Engines Construction:

 4 Stroke petrol and diesel  2 Stroke petrol and diesel  Rotary/Wankel

4 Stroke Petrol

Compression Exhaust Intake Stroke Power Stroke Stroke Stroke

A. Intake Stroke

 The first stroke of the cycle is the intake stroke.  As the piston moves away from top dead center (TDC), the intake valve opens.  The downward movement of the piston increases the volume of the cylinder above it, reducing the pressure in the cylinder. Low pressure (engine vacuum) causes the to push a mixture of air and fuel through the open intake valve.  As the piston reaches the bottom of its stroke, the reduction in pressure stops, causing the intake of air-fuel mixture to slow down. It does not stop because of the weight and movement of the air-fuel mixture.  It continues to enter the cylinder until the intake valve closes. The intake valve closes after the piston has reached bottom dead center (BDC).  This delayed closing of the valve increases the volumetric efficiency of the cylinder by packing as much air and fuel into it as possible.

B. Compression Stroke

 The compression stroke begins as the piston starts to move from BDC.  The intake valve closes, trapping the air-fuel mixture in the cylinder.  The upward movement of the piston compresses the air-fuel mixture, thus heating it up.  At TDC, the piston and cylinder walls form a combustion chamber in which the fuel will be burned.  The volume of the cylinder with the piston at BDC compared to the volume of the cylinder with the piston at TDC determines the compression ratio of the engine.

C. Power Stroke

 The power stroke begins as the compressed fuel mixture is ignited.  With the valves still closed, an electrical spark across the electrodes of a spark plug ignites the air-fuel mixture.  The burning fuel rapidly expands, creating a very high pressure against the top of the piston.  This drives the piston down toward BDC. The downward movement of the piston is transmitted through the connecting rod to the crankshaft.

D. Exhaust Stroke

 The exhaust valve opens just before the piston reaches BDC on the power stroke.  Pressure within the cylinder causes the exhaust gas to rush past the open valve and into the exhaust system.  Movement of the piston from BDC pushes most of the remaining exhaust gas from the cylinder.  As the piston nears TDC, the exhaust valve begins to close as the intake valve starts to open.  The exhaust stroke completes the four-stroke cycle.  The opening of the intake valve begins the cycle again.  This cycle occurs in each cylinder and is repeated over and over, as long as the engine is running.  It takes two full revolutions of the crankshaft to complete the four-stroke cycle.  One full revolution of the crankshaft is equal to 360 degrees of rotation; therefore, it takes 720 degrees to complete the four-stroke cycle.  During one piston stroke, the crankshaft rotates 180 degrees.

4 Stroke Diesel

 The operation of a is comparable to a gasoline engine.  They also have a number of components in common, (crankshaft, pistons, valves, camshaft, and water and oil .  However, diesel engines have compression ignition systems. Rather than relying on a spark for ignition, a diesel engine uses the heat produced by compressing air in the combustion chamber to ignite the fuel.  The compression ratio of diesel engines is typically three times (as high as 25:1) that of a gasoline engine.  As intake air is compressed, its temperature rises to 700°C to 900°C. Just before the air is fully compressed, a fuel sprays a small amount of diesel fuel into the cylinder. The high temperature of the compressed air instantly ignites the fuel.  The combustion causes increased heat in the cylinder and the resulting high pressure moves the piston down on its power stroke.

2 Stroke Engine

 This engine requires only two strokes of the piston to complete all four operations: intake, compression, power, and exhaust.  This is accomplished as follows:  Movement of the piston from BDC to TDC completes both intake and compression.  When the piston nears TDC, the compressed air/fuel mixture is ignited, causing an expansion of the gases. During this time, the intake and exhaust ports are closed.  Expanding gases in the cylinder force the piston down, rotating the crankshaft.  With the piston at BDC, the intake and exhaust ports are both open, allowing exhaust gases to leave the cylinder and air-fuel mixture to enter.

 Although the two-stroke-cycle engine is simple in design and lightweight because it lacks a valve train, it has not been widely used in automobiles.  It tends to be less fuel efficient and releases more pollutants into the atmosphere than four-stroke engines.

Rotary/

 The rotary engine, or Wankel engine, is similar to the standard piston engine in that it is a spark ignition, internal combustion engine.  Its design, however, is quite different. For one thing, the rotary engine uses a rotating motion rather than a reciprocating motion.  In addition, it uses ports rather than valves for controlling the intake of the air-fuel mixture and the exhaust of the combusted charge.

CHARACTERISTICS OF ROTARY ENGINE

 The rotating combustion chamber engine is small and light for the amount of power it produces, which makes it attractive for use in automobiles.  However, the rotary engine at present cannot compete with a piston gasoline engine in terms of durability, exhaust emissions, and economy.

3. Stationary Parts of an Engine

 cylinder block  cylinders  cylinder head or heads  crankcase  exhaust and intake manifolds

4. Engine System a. Fuel System

Animated cut through diagram of a typical fuel injector, a device used to deliver fuel to the internal combustion engine.

- Fuels burn faster and more efficiently when they present a large surface area to the oxygen in air. Liquid fuels must be atomized to create a fuel-air mixture; traditionally this was done with a in petrol engines and with fuel injection in diesel engines. Most modern petrol engines now use fuel injection too — though the is quite different. While diesel must be injected at an exact point in that engine cycle, no such precision is needed in a petrol engine. However, the lack of lubricity in petrol means that the themselves must be more sophisticated. - equipment in a motor vehicle or aircraft that delivers fuel to the engine.

 Carburetor Simpler reciprocating engines continue to use a carburetor to supply fuel into the cylinder. Although carburetor technology in automobiles reached a very high degree of sophistication and precision, from the mid-1980s it lost out on cost and flexibility to fuel injection. Simple forms of carburetor remain in widespread use in small engines such as lawn mowers and more sophisticated forms are still used in small motorcycles.  Fuel injection Larger gasoline engines used in automobiles have mostly moved to fuel injection systems (see Gasoline Direct Injection). Diesel engines have always used fuel injection system because the timing of the injection initiates and controls the combustion. Auto gas engines use either fuel injection systems or open- or closed-loop .

 Fuel pump Most internal combustion engines now require a fuel pump. Diesel engines use an all- mechanical precision pump system that delivers a timed injection direct into the combustion chamber, hence requiring a high delivery pressure to overcome the pressure of the combustion chamber. Petrol fuel injection delivers into the inlet tract at atmospheric pressure (or below) and timing is not involved, these pumps are normally driven electrically. Gas turbine and rocket engines use electrical systems. Other internal combustion engines like jet engines and rocket engines employ various methods of fuel delivery including impinging jets, gas/liquid shear, pre burners and others.

- a filter in the fuel line that screens out dirt and rust particles from the fuel.  Fuel gauge, fuel indicator - an indicator of the amount of fuel remaining in a vehicle.  Fuel line, petrol line, gas line - a that carries gasoline from a tank to a gasoline engine; "the car wouldn't start because dirt clogged the gas line"

b. Lubricating System

- Internal combustions engines require lubrication in operation that moving parts slide smoothly over each other. Insufficient lubrication subjects the parts of the engine to metal-to- metal contact, friction, heat build-up, rapid wear often culminating in parts becoming friction welded together e.g. pistons in their cylinders. Big end bearings seizing up will sometimes lead to a connecting rod breaking and poking out through the crankcase. Several different types of lubrication systems are used. Simple two-stroke engines are lubricated by oil mixed into the fuel or injected into the induction stream as a spray. Early slow- speed stationary and marine engines were lubricated by gravity from small chambers similar to those used on steam engines at the time — with an engine tender refilling these as needed. As engines were adapted for automotive and aircraft use, the need for a high power-to-weight ratio led to increased speeds, higher , and greater pressure on bearings which in turn required pressure-lubrication for crank bearings and connecting-rod journals. This was provided either by a direct lubrication from a pump, or indirectly by a jet of oil directed at pickup cups on the connecting rod ends which had the advantage of providing higher as the engine speed increased. c. Cooling System

- Combustion generates a great deal of heat, and some of this transfer to the walls of the engine. Failure will occur if the body of the engine is allowed to reach too high a temperature; either the engine will physically fail, or any lubricants used will degrade to the point that they no longer protect the engine. The lubricants must be clean as dirty lubricants may lead to over formation of sludge in the engines. Cooling systems usually employ air (air-cooled) or liquid (usually water) cooling, while some very hot engines using radioactive cooling (especially some rocket engines). Some high-altitude rocket engines use ablative cooling, where the walls gradually erode in a controlled fashion. Rockets in particular can use regenerative cooling, which uses the fuel to cool the solid parts of the engine.

 Piston Is a component of reciprocating engines. It is located in a cylinder and is made gas-tight by piston rings. Its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a and/or connecting rod. In two-stroke engines the piston also acts as a valve by covering and uncovering ports in the cylinder wall.

 Propelling nozzle

For jet engine forms of internal combustion engines, a propelling nozzle is present. This takes the high temperature, high pressure exhaust and expands and cools it. The exhaust leaves the nozzle going at much higher speed and provides thrust, as well as constricting the flow from the engine and raising the pressure in the rest of the engine, giving greater thrust for the exhaust mass that exits.  Crankshaft

A crankshaft for a 4-cylinder engine

Most reciprocating internal combustion engines end up turning a shaft. This means that the linear motion of a piston must be converted into rotation. This is typically achieved by a crankshaft.

 Flywheels 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 energy over from the power stroke into a subsequent compression stroke. Flywheels are present in most reciprocating engines to smooth out the power delivery over each rotation of the crank and in most automotive engines also mount a gear ring for a starter. The rotational 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 system and so by itself be out of balance, although most engines will use a neutral balance for the flywheel, enabling it to be balanced in a separate operation. The flywheel is also used as a mounting for the clutch or a converter in most automotive applications.

5. Engine Operation:

Following are the four strokes

A- Strokes- Reciprocating motion, used in reciprocating engines and other mechanisms, is back-and-forth motion. Each cycle of reciprocation consists of two opposite motions: there is a motion in one direction, and then a motion back in the opposite direction. Each of these is called a stroke. The term is also used to mean the length of the stroke. In a steam locomotive, or in a steam, Otto or Diesel piston engine, a stroke is the action of a piston travelling the full length of its locomotive cylinder or engine cylinder in one direction. The stroke length is determined by the cranks on the crankshaft. Stroke can also refer to the distance the piston travels. Engine displacement is dependent on both the diameter of the cylinder, known as its bore, and the stroke of the cylinder. In a piston less rotary engine, the term is applied to the corresponding rotor movement, see dead center. B- Two-stroke, Two-cycle, or Two-cycle engine- is a type of internal combustion engine which completes a power cycle in only one crankshaft revolution and with two strokes, or up and down movements, of the piston in comparison to a "four-stroke engine", which uses four strokes. This is accomplished by the end of the combustion stroke and the beginning of the compression stroke happening simultaneously and performing the intake and exhaust (or scavenging) functions at the same time. Two-stroke engines often provide high power-to-weight ratio, usually in a narrow range of rotational speeds called the "power band". Compared to 4-stroke engines, they have a greatly reduced number of moving parts, are more compact and significantly lighter. Two stroke engine is widely used employed where small power required for motor cycle like auto rickshaw, scooter. This type of engine is compact in size, easy for and simple in operation. In two stroke engine there are no inlet or exhaust valves as in four stroke engine.

C- Combustion Stroke- In this stroke both the ports still closed condition, the pressure of the expanding gases the piston towards BDC. The pressure in the crankcase is already rising. Later in down stroke exhaust port will be open & forced out the burnt gases, Very shortly after that the Inlet / Transfer port will also open to intake the fresh charge of fuel mixture, and engine is ready to start of the cycle.

D– Intake stroke- In suction stroke piston starts at Top Dead Center (TDC) of the cylinder and moves to the Bottom Dead Center (BDC). Outlet valve will be closed and inlet valve will be open to allowing the fresh charge of mixed fuel & air into the cylinder.

E – Compression stroke- In compression stroke, Once piston reaches BDC & moves back TDC, inlet valve will be closed, As the piston moves towards TDC, It compress air fuel mixture inside the cylinder & compression takes place, Hence it is called compression stroke. Too low a compression may result in the fuel/air mixture still burning when the piston reaches the bottom of the stroke and the exhaust valve opens.

F– Power/ Expansion stroke- In expansion stroke, Both the valves are closed, When piston reaches top of its stroke the fuel mixture is ignited by spark plug due to spark high temperature & pressure generated inside the cylinder & push down the piston to BDC, Hence it is known as expansion stroke.

G– Exhaust stroke- In this stroke exhaust valve is opened, when piston reaches to BDC & moves to upward. Piston pushes out the burnt gases to the atmosphere through the exhaust valve. Hence called exhaust stroke & the engine is ready to begin the cycle again.