ENGINES
WHAT IS AN ENGINE? – A MACHINE WITH MOVING PARTS THAT CONVERTS POWER INTO MOTION. – Engine converts force into motion.
History For Power Conversion • 1st century BC. Used water wheels, • End of 1st century AD Wind and steam powered machines developed by Heron of Alexandria • In 1206, al-Jazari employed a crank-conrod system for two of his water-raising machines • In the 13th century, the solid rocket motor was invented in China, first internal combustion engine
• In 1712,Improving on the design of the Newcomen steam engine • As for internal combustion piston engines, these were tested in France in 1807 by de Rivaz and independently
• They were theoretically advanced by Carnot in 1824 • In 1896, Karl Benz concludes the engine definition as we seeing now.
HEAT ENGINES
INTERNAL COMBUSTION ENGINES Reciprocating engine Gas turbine Air breathing jet engine Turbo-propeller engine Pulse detonation engine Pulse jet Ramjet Scramjet Liquid air cycle engine/Reaction Engines SABRE
EXTERNAL COMBUSTION ENGINES Steam engines
Function of a heat engine is burn a fuel to create heat
RECIPROCATING ENGINE CLASSIFIED WITH STROKES OF ENGINE • Two stroke engine • Four stroke engine
CLASSIFIED WITH FUEL USING
• Diesel engine • Petrol engine
RECIPROCATING ENGINE CLASSIFIED WITH STROKES OF ENGINE
• Two stroke engine • Four stroke engine
CLASSIFIED WITH FUEL USING
• Diesel engine
• Petrol engine
Two stroke engine • In Two stroke engine make one power in one full revolution of the crank shaft • For this piston takes two strokes for this
MAIN PARTS
• Cylinder • Piston and piston rings • Gudgeon pin • Cylinder head and cylinder liners • Connecting rod • Crank and crank shaft • Spark plug • Carbonator • Cylinder casing
Two stroke engine • Arrangement of engine:-
Piston functions • On one side of the piston is the combustion chamber, where the piston is compressing the air/fuel mixture and capturing the energy released by the ignition of the fuel. • On the other side of the piston is the crankcase, where the piston is creating a vacuum to suck in air/fuel from the carburetor through the reed valve and then pressurizing the crankcase so that air/fuel is forced into the combustion chamber. • Meanwhile, the sides of the piston are acting like valves, covering and uncovering the intake and exhaust ports drilled into the side of the cylinder wall.
1 ) The piston moves up from bottom
dead center (BDC) to top dead center (TDC). Both the transfer and exhaust ports covered by the piston. Air fuel mixture from carburetor is transferred already into engine cylinder is compressed by the moving piston. The pressure and temperature increases at the end of compression.
2 ) As the piston reaches the TDC the
charge ignited by means of electric spark provided by the spark plug. At the same time the piston uncovers inlet port and fresh charge enters the crankcase as shown in Figure
3 ) The gases expands in the cylinder due
to its combustion and thus the piston moves down, hence useful work is obtained. During this movement charge in the crankcase is partially compressed and this is known as crank case compression
3
4 ) At the end of expansion, exhaust
port is uncovered. The burnt gases escape to atmosphere, during this time the transfer port is also open. The partially compressed charge from crankcase enters to the cylinder through transfer port. The special shape provides the cycle reduce the escape of fresh charge along with the burned product.
4
Four stroke engine
• Internal combustion piston engine Components of a typical, four stroke cycle, internal combustion piston engine. E - Exhaust camshaft I - Intake camshaft S - Spark plug V - Valves P - Piston R - Connecting rod C - Crankshaft W - Water jacket for coolant flow