The piston head need to prevent the high temperature, high pressure gas into the
crankcase, and prevent oil from entering the combustion chamber; the top of the
piston absorbed most of the heat also passed to the cylinder through the piston
head, and then through the cooling medium.
The piston head is processed with
a plurality of grooves which are arranged on the piston ring, and the number of
the piston rings is determined by the requirements of the seal, which is related
to the rotation speed of the engine and the cylinder pressure.