Four-stroke engines are the most common internal combustion engine used in automobiles, like trucks, cars, and some modern motorbikes (most motorbikes work with a two-stroke engine). Four-stroke is known as the combustion cycle. It occurs during the combustion process in the internal part of an engine. A four-stroke engine transfers power stroke for every two periods of the piston or the four-piston strokes. So, what are the things to know about the four-stroke engines?
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The four-stroke cycle
The following explained below is the combustion cycle of the four-stroke engine. That is, all these processes must be accomplished before a vehicle can move. these processes are:
- intake/inlet stroke: this is the first stage of the combustion cycle; at this stage, the piston moves downward in order to allow the fuel and air to enter the chamber.
- Compression stroke: at this stage, the intake valve is closed, blocking the air-fuel mixture from escaping. The piston moves up the chamber, making the air and fuel compressed. At the end of the stroke, the availability of a spark plug allows the ignition of the air-fuel mixture, providing the energy required for the combustion.
- Power stroke: after the combustion takes place, the heat obtained from the combusting hydrocarbon increases the pressure, giving enough energy to push down the piston and create the power output.
- Exhaust stroke: this is the final stage of the combustion cycle; it occurs when the piston moves back downward, and the exhaust valve opens. As the valve opens, the exhaust gas is pushed out by the piston when it moves back upwards.
The thermal efficiency of an engine is the ability to convert the fuel (chemical energy) to mechanical energy. This energy will vary due to the design and model of the vehicle. Typically, gasoline engines are opportune to convert 20% of fuel (chemical energy) to mechanical energy. 15% of it is used to move the wheels, and 5% is lost to its mechanical elements and friction.
However, the engine can be improved through thermodynamic efficiency through a higher compression ratio. The ratio is determined between the maximum and minimum volume of the engine chamber. An engine with a higher ratio will allow the fuel-air mixture to be immense, which will produce higher pressure, make the housing hotter, and increase thermal efficiency.
Check out: Diesel engines and gasoline engines: Detailed explanation
Diagram of four-stroke engines:
Watch this video if you need more info on Four-stroke engines:
Related Article:
- Difference between 2-stroke and 4-stroke engines
- Applications, Pros and Cons of Two-Stroke Engines
- Understanding two-stroke diesel and gasoline engines
That’s all for this article where we discussed
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