The piston is an important part of the excavator engine. Its main function is to withstand the gas pressure and transmit it to the connecting rod through the piston pin to drive the crankshaft to rotate. The top of the piston is also an integral part of the combustion chamber. The following Komatsu excavator parts factory will introduce the piston in detail:
Working conditions: The piston works under the conditions of high temperature, high pressure, high speed and poor lubrication. The piston is in direct contact with the high-temperature gas, and the instantaneous temperature can reach more than 2500K. Therefore, the heating is serious and the heat dissipation conditions are very poor, so the temperature of the piston is very high during operation, the top is as high as 600-700K, and the temperature distribution is very uneven; the top of the piston is subjected to The gas pressure is very high, especially the working stroke pressure is the largest, the gasoline engine is as high as 3-5MPa, and the diesel engine is as high as 6-9MPa, which makes the piston produce impact and bear the effect of side pressure; the piston moves at a high speed in the cylinder (8 ~12m/s) reciprocating motion, and the speed is constantly changing, which produces a large inertial force, which makes the piston subject to a large additional load.
When the piston works under such harsh conditions, it will deform and accelerate the wear, and it will also generate additional load and thermal stress, and at the same time, it will be chemically corroded by the gas. Hence the requirement:
(1), there must be sufficient rigidity and strength, and the reliability of force transmission;
(2), good thermal conductivity, high pressure resistance, high temperature resistance, wear resistance;
(3) The mass is small, the weight is light, and the reciprocating inertial force is minimized. Aluminum alloy materials basically meet the above requirements. Therefore, high-strength aluminum alloys are generally used for pistons, but high-grade cast iron or heat-resistant steel are used in some low-speed diesel engines.