Free Essay About 4-Stroke Engine

Piston: Pistons of 4-stroke engine moves between Bottom Dead Centre (BDC) and Top Dead Centre (TDC) to complete a single thermodynamic cycle. Latest 4-stroke automobiles are designed to run on unleaded petrol. A 4-stroke engine is called an internal combustion engine, where the piston completes 4-separate strokes they are intake, compression, power and exhaust. The intake stroke of the piston moves down (or BDC) and the engine takes a cylinder full of air and petrol. Then the piston moves back (TDC) and thus compress the petrol and air mixture. When a piston reaches at the top the spark plug of the engine generate a timely spark to ignite the fuel and ignition drives the piston down this is called power and in its fourth stroke or exhaust when the piston reaches at the bottom, the exhaust valve opens, and release the burnt gases from combustion chamber. Aluminium alloy pistons commonly used in majority pistons for automobiles; they are produced by forging the alloy in order to make the metal more durable. An oil flow provision in the pistons maintains a lubricating layer of oil between the surface of the piston and cylinder. Three rings are placed on the pistons the first two rings are compression rings, and the third is oil control ring. The rings are made up of cast alloy iron and heat resistant; the rings are used to regulate the flow of oil within the combustion chamber wall of the engine.
Connecting Rod: The connecting rods of 4-stroke engines are also termed as con rod. Con rod connects the crank or the crankshaft of an engine. It has two ends one small end that is fastened with the piston by a pin and bigger head is fastened with the crank with the help of a crank pin. The connecting rods are used to convert linear motion to rotational motion. The connecting rods of an internal combustion engine are required to be built strong and at the same time light so few metals like Titanium or Aluminium are found fit for making the connecting rods or con rods. Aluminium rods are usually applied as connecting rods of the automobiles for daily street driving.
Cylinder head: Or just head of an internal combustion engine fitted at the top most part of a 4-stroke engine that closes the top most part or TDC of the engine to form a chamber of combustion. Cylinder head of a 4-stroke engine consist of four parts they are a port or valve, inlet, exhaust and the spark plug. In most cases, cylinder heads have more than two valves per cylinder and sometimes even more. Different types of valves are in use in cylinder heads most popular is the poppet valve and is commonly used where overhead valves are fitted. In a 4-stroke engine air and fuel enters the cylinder through valve, that is located at the cylinder head, the valve control the timing of flow into the cylinder, as the air passes through the valve to the inlet; the inlet air filter cleans the air and a timed spark from spark plug ignite the mixture of a compressed mixture of air and fuel and exhaust valve opens and releases the burnt fuel. As the exhaust valve is opened on pressure, therefore, it is less critically designed than an inlet valve.
Cylinder: It is where the entire system of operation in an engine takes place. The entire process of combustion takes place in the following manner. The downward movement of the piston or movement towards the BDC creates a low pressure within the cylinder and open intake valve to allow the air and fuel mixture within the cylinder to fill the low pressure zone in the cylinder. Now, the piston starts moving upward or TDC and the upward movement of the piston closes the intake valve and the air fuel mixture are now sealed within the cylinder. In this position, the trapped air and fuel mixture is vaporized and ignited. The increase in air, fuel mixture temperature, is occurred throughout the cylinder of the combustion chamber to ensure faster fuel oxidation after ignition. The increased fuel vaporization occurs in small droplets and gets vaporized from the generated heat and the vaporized mixture get completely burnt. The more molecules are compressed in the cylinder, the more energy is obtained from the combustion process.