The four stroke principle upon which most modern automobile engines work was discovered by a French engineer, Alphonse Beau de Rochas in 1862. The four stroke cycle is often called the Otto cycle after the german Nikolaus August Otto who designed un engine on that principle in 1876. Show
A stroke is the movement of the piston from TDC (top dead center) to BDC (bottom dead center), or from BDC to TDC. There are four strokes in one four stroke cycle of the engine. They are: the intake stroke, compression stroke, power stroke and exhaust stroke.
The four stroke cycle is considerably more complicated than this simple explanation. When the engine is running, the timing of the opening and closing of the valves actually determines when each stroke effectively begins. Valve timing will be discussed with greater detail in one of the next articles. Bibliography: – https://www.britannica.com/technology/four-stroke-cycle – Automotive Engines – Tim Gilles A four-stroke engine is an internal combustion engine that utilises four distinct piston strokes (intake, compression, power, and exhaust) to complete one operating cycle. A complete operation in a four-stroke engine requires two revolutions (7200) of the crankshaft. In this article, let’s study the four-stroke engine. PistonIn an engine, a piston transfers the expanding forces of gas to mechanical rotation of the crankshaft through a connecting rod. CrankshaftA crankshaft is a part that converts the reciprocating motion to rotational motion. Connecting RodIt transfers motion from a piston to crankshaft acting as a lever arm FlywheelThe flywheel is a rotating mechanical device that is used to store energy. Inlet and Outlet ValvesIt allows us to enter fresh air with fuel & to exit the spent air-fuel mixture from the cylinder. Spark PlugIt is a device that delivers electric current to the combustion chamber which ignites the air-fuel mixture leading to the abrupt expansion of gas. Four Stroke Engine CycleThe four strokes of the engine go by the following names:  Suction/Intake StrokeIntake stroke occurs when the air-fuel mixture is introduced to the combustion chamber. In this stroke, the piston moves from TDC (Top Dead Center – the farthest position of piston to the crankshaft) to BDC (Bottom Dead Center – the nearest position of piston to the crankshaft.) The movement of the piston towards the BDC creates a low-pressure area in the cylinder. The inlet valve remains to open a few degrees of crankshaft rotation after BDC. The intake valve then closes and the air-fuel mixture is sealed in the cylinder
Compression StrokeIn compression stroke, the trapped air-fuel mixture is compressed inside the cylinder. During the stroke, the piston moves from BDC to TDC compressing the air-fuel mixture. The momentum of the flywheel helps the piston move forward. Compressing the air-fuel mixture allows more energy to be released when the charge is ignited. The charge is the volume of compressed air-fuel mixture trapped inside the combustion chamber ready for ignition. The inlet and outlet valves must be closed to ensure that the cylinder is sealed resulting in compression.
Power/Combustion StrokeThe second rotation of the crankshaft has begun when it completes a full rotation during the compression stroke. The power stroke occurs when the compressed air-fuel mixture is ignited with the help of a spark plug. Ignition or Combustion is the rapid, oxidizing chemical reaction in which a fuel chemically combines with oxygen in the atmosphere and releases energy in the form of heat. The hot expanding gases force the piston head away from the cylinder head.
Exhaust StrokeAs the piston reaches BDC during the power stroke, combustion is complete and the cylinder is filled with exhaust gases. The exhaust valves open during this stroke and the inertia of the flywheel and other moving parts push the piston back to TDC, forcing the exhaust gases through the open exhaust valve. At the end of the exhaust stroke, the piston is at TDC and one operating cycle has been completed.
Comparison Between 2-stroke engine and a 4-stroke engine
Two-stroke engines are typically found in smaller applications such as chainsaws, boat motors, and dirt bikes. Four-stroke engines are found in go-karts, lawnmowers, and combustion engines in your car. Stay tuned to BYJU’S and fall in love with learning! Frequently Asked Questions – FAQs A four-stroke engine is an internal combustion engine that utilizes four distinct piston
strokes to complete one operating cycle. Various parts of four stroke engine are: Which is heavier? Two stroke engine or four stroke engine?A four-stroke engine weighs 50% heavier than a two-stroke engine, and hence four-stroke engine is heavier. Which type of engine tend to wear out fast?The two stroke engine tends to wear out fast since it is designed to operate at a higher RPM. What are the three applications of four-stroke engines?Four-stroke engines are used in: What are the 4 steps in the four engine cycle process in order?4-stroke internal combustion engine. 1:fuel injection, 2:ignition, 3:expansion(work is done), 4:exhaust.
Is a car engine 4 cycle?Most modern internal combustion-powered vehicles are 4-strokes, powered by either gasoline or diesel fuel. During engine operation, pistons go through 4 events to achieve each power cycle. The definition of an event is an up or down piston motion.
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What are the four cycles of an engine
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