Engine
An engine is a machine that converts energy into movement. It is the beating heart of every car and ensures it can do what it is meant to do: drive! Cars use so-called internal combustion engines, meaning the fuel is burned inside the engine itself. This combustion generates pressure, which is then converted into motion.
The most commonly used fuels are petrol, diesel, and LPG. Nowadays, experiments are also being conducted with alternative fuels such as hydrogen, ethanol, or natural gas. Normally, an engine can only run on one type of fuel.
The Cylinders
The combustion process takes place in the cylinders. Depending on how the cylinders are positioned, different types of engines can be distinguished. Most passenger cars have an inline engine, where the cylinders are neatly arranged in a single row.
With a V-engine, the cylinders are positioned in two rows facing each other in a V-shape. For example, a V12 engine has 6 cylinders on the left and 6 on the right. There is also the boxer engine, where the cylinders lie directly opposite each other.
The most important parts of a cylinder are the intake and exhaust valves, spark plug, and piston. The cylinder capacity (in cc or litres) indicates how much gas (air-fuel mixture) can be burned in the cylinders.
The Four-Stroke Principle
Modern engines all operate according to the four-stroke principle. This means the engine works in four steps. In the first step (the intake stroke), the piston moves downward and fresh air and fuel are drawn into the cylinder through the intake valve. During the compression stroke, the piston moves upward again and the air and fuel are mixed and compressed. Both the intake and exhaust valves are closed.
The third step is the power stroke. The spark plug ignites the air-fuel mixture, causing a small explosion. The resulting pressure pushes the piston back down. During the exhaust stroke, the piston moves up again and the waste gases are expelled through the open exhaust valve. The entire process then starts over.
The Crankshaft
THE LINK BETWEEN PISTONS AND WHEELS
The described principle applies to petrol engines. In diesel engines, only air is drawn in during the intake stroke. The diesel fuel is injected during the third step and then ignites spontaneously (without the help of a spark plug) due to the heat generated by compressing the air.
So how does the movement of the pistons make your car’s wheels turn? That’s the job of the crankshaft. It is connected to the pistons via connecting rods and converts their up-and-down movement into a rotating motion. This rotation is then transmitted further through the necessary intermediate steps.