Petrol Engine Ghannupur Amritsar

GOVT. SEC. SCHOOL GHANUPUR AMRITSAR

PROJECT BY: KARAMJIT SINGH X-A SURINDER SINGH X-A PARGAT SINGH

IX-A

INTRODUCTION: Petrol engine was introduced by the engineers Gottlieb Daimler and Karl Benz (both from Germany) in 1885. It is considered as one of biggest achievement in the automotive field. It uses petrol called as gasoline in USA as a fuel. It is made up of about 150 moving parts. Within the engine burning of fuel mixed with air causes hot gases to expand against parts of the engine and force them to move. So petrol engines are called internalcombustion engines. Petrol engines are compact and light in weight for the power they produce. The rate at which it produces work is usually measured in horsepower or watts. Parts of a petrol engine Following are some of the important parts of petrol engine: 1) Cylinders 2) Cylinder block 3) Piston and Connecting rods 4) Cylinder head Crankcase 5) Valves 6) Crank shaft Flywheel 7) Exhaust system 8) Camshaft Fuel system 9) Lubrication system 10) Ignition system

Working of a petrol engine Generally the vehicles using petrol/gasoline engine have four strokes as they are more efficient than two stroke engine and give complete combustion of fuel to optimum use. The four-stroke cycle engine has four strokes namely intake, compression, power, and exhaust strokes. a) Suction or intake stroke: Initially when engine is started piston moves downwards towards bottom of the cylinder which creates low pressure at top. Due to this intake valve opens and the fuel mixture containing petrol vapors and air are sucked in by the cylinder. Carburetor now decides in what ratio gasoline/petrol and air should be mixed. b) The compression stroke: After this the inlet valve gets closed. The piston now moves towards the top of cylinder and compresses the fuel mixture to one tenth of its initial volume. The temperature and pressure inside the cylinder increases due to compression caused. c) The power stroke: During this stroke the inlet and exhaust valve remains closed. As the piston reaches near top position spark plug produces an electric spark. Combustion is started by an ignition system that fires a high voltage spark through a field replaceable air gap called a

sparkplug. The spark produced causes explosion of fuel. The hot gases expand and force the piston to move downwards. The piston is linked to the piston rod and the piston rod to the crank shaft. They all move each other due to the link between them. The crank shaft is connected to the wheels of a car. As the crank shaft movess, the wheels rotate and move the car. d) The exhaust stroke: In this stroke the exhaust valve remains open at the start. The piston is forced to move upwards because of the momentum gained. This forces gases to move through the exhaust valve into the atmosphere. Now the exhaust valve closes and the intake valve opens. After this the four strokes of the engine are repeated again and again