A car engine is also known as an internal combustion engine, and is designed to use small, controlled explosions to create the power necessary to move the vehicle. This type of engine is used in lawnmowers, motorcycles and other motorized devices. There have been many improvements on the design to improve efficiency and power, but the car engine is really a very simple device.
All automobile engines are designed to use a four stroke combustion cycle. The four strokes are the intake, compression, combustion and exhaust. These strokes are repeated in quick succession to generate power. All parts of the combustion cycle take place within an enclosed car engine.
To understand how a car engine works, picture a windmill. The arms of the windmill are moved by the force of the wind. As the wind moves the arms, the windmill creates power that can be used to move heavy grinding stones or generate electricity.
The automobile engine works in a very similar way. Instead of wind, a small, controlled explosion forces the piston, or "arms," of the engine to move. When the energy from the explosion is almost worn out, another explosion occurs, forcing the pistons to move again. This recurring cycle generates the power needed.
The piston is a metal rod that is connected by a crankshaft to the connecting rod. During the intake cycle, the intake valve opens and the piston moves down, to start the cycle. This motion brings a cylinder full of air and a small amount of gas into the engine.
In the compression cycle, the piston moves up and reduces the space of the air and fuel. The smaller the space, the more powerful the explosion will be. The seal on this space must be airtight, so that no energy is lost.
At the top of the cycle, the spark plug releases a spark that explodes the gasoline. The power of the explosion forces the piston down. If the spark does not occur at the right moment, the explosion does not happen.
At the bottom of the stroke, an exhaust valve opens so that the waste gas from the explosion can leave the engine. This gas is moved down through the pressure of the recurring explosions to the catalytic converter and muffler. The air is cleaned of the larger pollutants and the exhaust exits the vehicle through the tailpipe.
The speed of the cycle determines the speed of the vehicle. When the driver increases the amount of gas going to the engine, the engine pistons increase their movement. This faster pace results in an increase in the speed of the combustion cycle.
The spark plugs play a critical role in the car engine, as they provide the spark that initiates the explosion. Spark plug designers continually try to improve on this design. The more sparks that can be issued by the spark plug within a short period of time, the greater speeds the engine can achieve.