THE FOUR-STROKE CYCLE

THE FOUR-STROKE CYCLE

Cranckshaft role is to transmit the motion created by the combustion of air-fuel mixture to the gear and, finally to the wheels

WHAT'S THAT?

MECHANICAL PARTS

This type of engine was invented during the 19th century by Nicoulas August Otto

It consists in the most common device in the world able to create motion in our vehichles

HOW DOES IT WORKS?

INTAKE

CRANKSHAFT

PISTONS

TIMING BELT

CONNECTING RODS

SPARK PLUG

VALVES

The piston's role is to absorb the energy emitted by the combustion and transorm it in kinetic energy which produces motion

Cranckshaft role is to transmit the motion created by the combustion of air-fuel mixture to the gear and, finally to the wheels

Spark plug's role is to generate a spark which is foundamental to make the air-fuel mixture explodes in case of benzine engine

The intake and exhaust valves manage the intake and the exhaust stroke by opening or closing themselves

The timing belt connects the camshafts to the crankshaft in order to permit that at a certain rotation of the crankshaft, the camshafts rotate of a certain angle

Connecting rod connects the rod journal to the piston and this part is able to tranform linear movement into circular movement

CAMSHAFT

The camshaft manages the opening and the closing of the intake and exhaust valves

During the intake stroke the intake valves get opened by the camshaft and, inside the cylinder enters the air-fuel mixture. In thos phase the piston i getting down to suck this mixture

COMPRESSION

The piston finally gets up and, by doing this compresses the air fuel mixture which consequently gets increased the pression and the heat

COMBUSTION

The higher temperature reached , anyway, it's not enough to make the air fuel mixture explode. To reach this, It is foundamental the presence of a spark. In this stroke is generated all the energy which the other strokes need. The piston is pushed to the bottom dead center

EXHAUST

In this stroke the camshaft opens the exhaust valves letting the exhaust gas be exhausted in the atmosphere. In this stroke the piston pushes the exhaust gas outside the cylinder reaching the top dead center

CYLINDER

It's the place where all the strokes happen. The main points of the cylinder are the top dead center and the bottom dead center. The distance between TDC and BDC is called engine displacement. The ratio between the volume of the air when the piston at TDC and the one at BDC is called compression ratio. An high value of compression ratio means that the air-fuel mixture will be greatly compressed when the piston gets the TDC