presentation on petrol engine
TRANSCRIPT
Roll No:14ME112
Syed Ashraf Ali Shah Rizvi
Mehran UET, Jamshoro
Department of Mechanical Engineering
What is an Engine?An ENGINE is a machine used to convert HEAT ENERGY into MECHANICAL ENERGY.
PETROL ENGINE
PETROL ENGINEA petrol engine (known as a gasoline engine) is an INTERNAL COMBUSTION engine with the spark ignition. So it is also known as spark ignition engine(S.I. Engine).
Fuel used In a petrol engine is a gasoline ( Petrol ) and similar volatile fuel.
The petrol engine works on principle of theoretically OTTO CYCLE.
OTTO CYCLEAn OTTO cycle is an idealized thermodynamic cycle that describes the functioning of a typical spark ignition piston engine. It is the thermodynamic cycle most commonly found in automobile engines.
There are TWO types of Petrol Engines
- 4 STROKE PETROL ENGINE.
- 2 STROKE PETROL ENGINE.
4 STROKE PETROL ENGINE
A FOUR STROKE PETROL ENGINE shown in figure.
The valve operating the inlet is called inlet valve and the valve operating the exhaust is called exhaust valve. The spark plug fitted at the top of cylinder head initiates the ignition of the air fuel mixture.
The piston performs four stroke to complete one working cycle. The four different strokes are;
Suction stroke
Compression stroke
Power stroke
Exhaust stroke
INTAKE STROKEINTAKE VALVE OPEN
EXHAUST VALVE CLOSED
PISTON GO TO TDC TO BDC
AIR-FUEL MIXTURE ENTER IN TO THE CYLINDER
COMPRESSION STROKE INTAKE VALVE CLOSED
EXHAUST VALVE CLOSED
PISTON GO TO BDC TO TDC
AIR-FUEL MIXTURE COMPRESSED IN TO THE CYLINDER
POWER STROKEINTAKE VALVE CLOSED
EXHAUST VALVE CLOSED
AIR-FUEL MIXTURE BURN INTO THE COMBUSTION CHAMBER
PISTON GO TO TDC TO BDC
EXHAUST STROKEINTAKE VALVE CLOSED
EXHAUST VALVE OPEN
PISTON GO TO BDC TO TDC
EXHAUST GAS OUT THROUGH THE EXHAUST VALVE
THE WORKING OF 4 - STROKE PETROL ENGINE.
Exhaust valve Inlet valve
Petrol and air mixtureExhaust gases TDC
BDC
Spark plug
TWO STROKE PETROL ENGINE
• As the name itself implies, all the processes in two stroke cycle engine are completed in two strokes.
In two stroke engine cycle operations suction , compression , expansion and exhaust are completed in one complete revolution.These engines have one power stroke per revolution of the crank shaft.Two-stroke engines do not have valves, which simplifies their construction and lowers their weight.
Major parts •CYLINDER•PISTON•CRANK SHAFT •ENGINE VALVE •CONNECTING ROD•CAM SHAFT•SPARK PLUG
Cylinder in the ENGINE is
Piston in the ENGINE is
Crankshaft in the ENGINE is
Engine valve in the ENGINE is
Connecting rod in the ENGINE is
Camshaft in the ENGINE is
Spark Plug in the ENGINE is
Advantages of Petrol engine High engine speeds of about 3000 rpm.
Lighter in a weight because maximum pressure and temperature is less.
Less initial cost.
Less maintenance cost.
Disadvantages of Petrol engine
low compression ratio ranging from 6 to 10.
The thermal efficiency is lower due to lower compression ratio.
Running cost higher because petrol is costly.