Scooter pistonDuring the working cycle of an internal combustion engine, the energy bound in the fuel in the cylinder is converted into heat and pressure in a very short time. This process takes place explosively so that the temperature and pressure values in the cylinder rise very sharply in fractions of a second. In mechanical engineering, a piston is a movable component of the combustion chamber which, together with the cylinder, forms a closed cavity. The piston is responsible for sealing the combustion chamber. In addition, the piston performs other important tasks. It closes off the combustion chamber, dissipates the heat generated in the combustion chamber, supports charge change and mixture formation by means of a special shape of the piston surface on the combustion chamber side. The piston is a hollow cylinder closed on one side in its basic structure, consisting of the following areas: piston hub, shaft and piston crown with ring section. Today, pistonfor reciprocating piston engines are mainly made of cast aluminium alloys. The blank is produced by gravity die casting.
piston forceThe piston is exposed to a wide variety of forces as it moves up and down continuously in the cylinder while the engine is running. At the respective reversal point it is strongly braked and then accelerated again. This creates mass inertia forces which act on the piston. Together with the forces generated by the gas pressure, they form the piston force. The piston force is transmitted to the connecting rod and the crankshaft. However, the connecting rod is only exactly vertical at the upper and lower reversal points (also called dead centre). Due to the inclined position of the connecting rod, the piston is pressed against the cylinder wall. During a working cycle, the level of this force changes direction several times and is dependent on the piston force and the angle at which the piston crown and connecting rod axis are in relation to each other. The lateral force can also be derived from the parallel force program.
Each piston is equipped with piston rings. The piston ring is a sealing element on the piston. Its task is to seal the working chamber, to dissipate the heat of combustion from the piston to the cooled cylinder wall and to dose the lubricating oil between the running surface of the ring and the cylinder wall.