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ENGINEERING STUFF TO KNOW: ENGINES (2 STROKE & 4 STROKE)

  • Farrukh Zaheer
  • Jun 3, 2016
  • 3 min read

Engine's have been a great invention, a way of converting one form of energy into another. For Instance, Steam engines convert chemical energy into mechanical energy. Engine's require a mixture of air and gasoline in proportionate amounts to function. Below is some of the information that is explained in simple words and is must know for every individual no matter what ever profession they belong from.

Above diagram is the engine of a car, the main parts of the engine are labeled on the diagram. However, the three main parts of the engine are the Piston, Crank Shaft, Connecting Rod that combined together perform most of the action.


There are two types of Engines known as the External Combustion Engine and the Internal Combustion Engine.


External Combustion Engine: External combustion engine is the opposite case. In this type of an engine the combustion process takes outside the engine parameter.


Internal Combustion Engine: In this type of an engine, the combustion process responsible for the production of output happens inside the cylinder located within the engine.


FURTHER CLASSIFICATIONS OF INTERNAL COMBUSTION ENGINES:


1- Two Stroke Engine

In a two stroke engine, the piston is designated to move two times during the whole process which ensures one complete rotation of the crankshaft. The piston is a main component of this engine and performs three functions: Used for compression, serves as a wall for Inter and Exhaust routes.


In Stroke 1: As the piston moves upwards, it opens up the inlet value allowing the mixture of air and gasoline to flow within the chamber. On the other hand, the piston compresses the mixture of air and gasoline already in the cylinder. The ignition spark lights up to initiate the combustion processes that generates a repulsive force pushing the piston downwards.


In Stroke 2: As the piston moves down the exhaust port opens up allowing the exhaust fumes due to the previous compression process. While the exhaust gasses are being released the fuel below the piston transfers to the upper chamber. This process keeps on repeating itself N number of times a minute to produce the Mechanical work.


2- Four Stroke Engine

In a four stroke engine the piston movement happens four times in different processes. In this type of an engine the crankshaft rotates two times as compared to two stroke engine in which just one rotation of crankshaft occurs.


(a) The first process is the intake cycle. In this process the Inlet port is open allowing the mixture of fuel and gasoline to run in filling the space within the cylinder and pushing the piston downwards at the same time.


(b) Once the cylinder is full of air and gasoline mixture the inlet value shuts down and the compression process initiates, the piston compresses the in compressible fuel mixture increasing the pressure within the cylinder.


(c) This process is referred as the power or ignition process. The spark ignites at the spark plug point that initiates the combustion processes to begin by introducing oxygen to the fuel mixture. This generates an enormous amount of energy pushing the piston downwards.


(d) This is final phase of the 4 stroke engine in which as the piston goes down the exhaust value opens up allowing the exhaust gases from previous ignition process to escape. As the fumes escape the piston rises up opening up the inlet value to allow new fuel mixture into the cylinder while it closes the exhaust value simultaneously. This process is repeated N number of times a minute and is the working of a four stroke engine.


Comparison of 4 Stroke Engine over 2 Stroke Engine

 
 
 

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