What is a four Stroke Engine four Stroke Engine
Most of the engines used to run most of the vehicles as well as machineries are four-stroke engines. These engines follow the Otto cycle named after Nicolaus Otto who was able to produce a functioning four stroke engine that was originally patented and introduced by Eugenio Barsanti and Felice Matteucci in 1854.
The mechanisms behind this type of engine can be categorized into four namely intake stroke, compression stroke, power stroke and exhaust stroke. The names are primarily based from the four movements of the piston in the engine firing cycle.
FIRST STROKE INTAKE STROKE
In the intake stroke, the crankshaft rotates that is responsible for pulling down the piston. The intake valve opens and the mixture of fuel and air go into the combustion chamber then to the cylinder. As the electrical switch opens, the exhaust valve is then closed. The low pressure of the fuel-air mixture will then cause the intake valve to close as the piston moves to the right.
SECOND STROKE COMPRESSION STROKE
When the piston moves to the right, the volume of the fuel and air mixture are reduced as they are compressed inside the combustion chamber and cylinder. The decrease in volume, however, results in an increase in increase of gas pressure. The electrical contact stays open in this stroke until the volume reaches the lowest and the pressure reaches the highest point that would signal the electrical contact to close.
THIRD STROKE POWER STROKE
In this stroke, the electrical contact opens again. This prompts the ignition of the fuel-air mixture found in the combustion chamber. This is the only time that heat will be generated and exhaust will start forming inside the chamber. Since until this time both the intake and the exhaust valve are still closed, the chamber as well as the remaining gases will undergo an increase in temperature and this will lead also to an increase in pressure. Power stroke actually commence when the high pressure of gasses that acts on the piston causes it to move to the left. Once the piston moves, the volume of the gas increases and it would then cause a decrease in pressure and temperature of the gas.
FOURTH STROKE EXHAUST
Power stroke ends when the piston is located on the far left position. The heat remaining from the previous stroke is now transmitted to the liquid in the water jacket and the pressure will reach approximately the atmospheric pressure that will then result for the exhaust valve to open. This is the start of the exhaust stroke which aims of removing the by-products of the ignition cycle before another cycle begins.
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