Petrol Engine(bhargo Camp)

Petrol Engine 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 internal-combustion 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.

Working of Petrol Engine: The Working of an internal combustion engine is divided into four stages called four strokes of the engine and hence the engine is called a Four Stroke Engine.

1. The Intake Stroke: When the engine starts, the piston moves downwards in the cylinder, because of which a region of low pressure is created in the cylinder, above the piston. At this moment, the intake valve opens and the fuel mixture (petrol vapour and air mixture) is sucked into the cylinder from the carburetor.

2. The Compression Stroke When the sufficient amount of the fuel mixture (petrol vapour and air mixture) has entered the cylinder, the intake valve gets closed. The piston is then forced to move upwards which compresses the fuel-mixture to about one-eighth of its original volume. Higher the compression ratio more will be the efficiency of the engine.

3. The Power Stroke Before the piston completes its upward movement, compressing the petrol vapour and air mixture, the spark plug produces a little electric spark inside the cylinder and this spark sets fire to the petrol-air mixture. The petrol vapour burns quickly in a little explosion, producing a large volume of gases and enormous heat. The heat thus produced expands the gases rapidly. The pressure of rapidly expanding hot gases pushes the piston downward with a great force. The piston pushes the piston rod and the piston rod pushes the crank shaft. The crank shaft is joined to the wheels of a car. When the crank shaft turns, the wheels rotate and move the car.

4. The Exhaust Stroke When the piston has been pushed to the bottom of the cylinder by the hot expanding gases in the power stroke, then the exhaust valve opens. After that, due to the momentum gained by the wheels, the piston is pushed upwards. The upward movement of the piston expels the spent gases through the exhaust valve into the atmosphere, carrying away the unused heat. The exhaust valve then closes, the intake valve opens up, and the above four strokes of the engine are repeated again and again.

Carburetor:-

It is the heart of gasoline engine. They meter the fuel and

mix it with the air in precise proportions. Old carburetors do spark advance by measuring the difference in pressure between the outside and inside of the carburetor. The amount of throttle advance is also measured. The engine's remains which may be carbon monoxide or unburned hydrocarbons shows

how

well

the

carburetor

is

working.

In new engines, a small computer is used to calculate these parameters and control one or more electric injectors. Most of the new cars use electronic fuel injection as it allows the engine computer to precisely control the fuel air mixture which increases energy efficiency and reduces pollution.

Classification based on number of stokes per cycle:-

Petrol Engine

Two Strokes

Four Strokes

1. Four Stroke petrol engine: The four stroke engine is called so because the Working of internal combustion engine is divided into four stages called four stroke of the engine

2. Two stroke petrol engine: From the name itself we get the idea about the functioning of the engine. The engine ignites fuel at every upward stroke, so there are two strokes for every ignition of fuel. They are called upward and downward stroke. As the piston moves in upward direction from bottom to top in the first stroke the air and fuel mixture gets compressed and ignited by spark plug as upward stroke comes to end. This results in an explosion of mixture which forces the piston to move downwards thereby producing power.

Application These engines are widely used in vehicles, portable power plants it supply the power to run pumps and other machinery on farms. Many small boats, aero planes, trucks and buses also use it