The function of the Copeland discus piston 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. 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. Therefore, the temperature of the piston is very high when working, the top is as high as 600-700K, and the temperature distribution is very uneven; the top of the piston bears The gas pressure is very high, especially when the work stroke pressure is the highest, the gasoline engine is as high as 3～5MPa, and the diesel engine is as high as 6～9MPa. ~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. Pistons working under such harsh conditions will deform and accelerate wear, as well as additional load and thermal stress, as well as being chemically corroded by the gas.

The structure of the Copeland discus piston
 
Generally, the Copeland discus piston is a cylindrical body. According to the working conditions and requirements of different engines, the piston itself has various structures. Generally, the piston is divided into three parts: the head, the skirt and the piston pin seat.
 
The head refers to the top of the piston and the ring groove part. The top of the piston completely depends on the requirements of the combustion chamber. The flat top or close to flat top design of the top is beneficial to reduce the contact area of ​​the piston with high-temperature gas and make the stress distribution uniform. Most gasoline engines use flat-topped pistons, and some engines (such as direct injection diesel engines and new in-cylinder injection gasoline engines) require a more complicated shape at the top of the piston in order to improve the combustion efficiency and reduce the deflagration to a minimum. , With a certain depth of pit as a part of the combustion chamber. The groove of the piston is called the ring groove, which is used to install the piston ring. The function of the piston ring is to seal, prevent air leakage and prevent oil from entering the combustion chamber.
 
The Copeland discus piston skirt refers to the lower part of the piston, and its function is to keep the piston as vertical as possible in the reciprocating motion, which is the guiding part of the piston.
 
The shape of the skirt of the Copeland discus piston is very exquisite, especially for light passenger cars like cars. Designers start from the structure and performance of the engine and often use their brains on the piston skirt to make the engine as compact as possible and run smoothly. .
 
The Copeland discus piston pin seat is the supporting part where the piston is connected to the connecting rod through the piston pin, and is located above the piston skirt. The special feature of the high-speed engine piston pin seat is that the pin seat hole is not necessarily on the same centerline plane as the piston, but can be offset a little bit to one side, that is, to the side where the piston contacts the cylinder wall during the work stroke. When the piston changes direction to the top dead center, the extent of the piston hitting the cylinder wall will be reduced, thereby reducing the engine noise.