Engine- provides the power to drive the vehicle’s wheel. 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- STROKE ENGINE ROTARY ENGINE 4- STROKE ENGINE External combustion engine (EC engine) - is a heat engine where an (internal) working fluid 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 piston engine- is a heat engine that uses one or more reciprocating pistons to convert pressure 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 vehicles; the steam engine, 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 cylinder block with rotating crankshaft as with a conventional radial engine, 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 bore 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 metal bolted to the top of cylinder block with head gasket 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 force 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 connecting rod, when piston moves downward sucks fresh air-fuel mixture in suction stroke & ignited inside the cylinder due to this high temperature 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 “crank 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 pump 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 atmospheric pressure 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 diesel engine is comparable to a gasoline engine. They also have a number of components in common, (crankshaft, pistons, valves, camshaft, and water and oil pumps.