The
piston in direct contact with the high temperature gas instantaneous
temperature can reach 2500K above, therefore, is serious, and the radiation
condition is very poor, so the piston when the temperature is high, top up to
600 ~ 700K, and the temperature distribution is not uniform; piston the top
under air pressure, especially the power stroke gasoline engine maximum
pressure, up to 3 ~ 5MPa, the diesel engine is up to 6 ~ 9MPa, which makes the
piston impact, and bear the side pressure; the piston in the cylinder at a high
speed (8 ~ 12m/s) reciprocating motion, and speed changes constantly, it
produces a large inertial force, the piston is great additional load. The
piston to work in such harsh conditions, will produce deformation and
accelerated wear, will produce additional load and thermal stress, at the same
time by the chemical action of gas.