General piston is cylindrical body, according to the working conditions and requirements of the different engine piston itself is constructed with a wide range, generally the piston is divided into three parts, head, skirt and piston pin for this little thing.
    The head refers to the part of the piston top ring groove. The piston top is completely depending on the requirements of the combustion chamber, the top with flat or nearly flattened design is conducive to the piston to reduce the area of ​​contact with the high temperature gas, so that the stress distribution uniform. Most gasoline flat top piston with more complex shapes, some engines (such as direct injection diesel engine and a new cylinder injection gasoline engine) in order to mixture formation needs to improve combustion efficiency, the deflagration as to minimize the need piston top , with a certain depth of the pits as part of the combustion chamber. The recess of the piston known as the ring groove, and for mounting the piston ring. The role of the piston ring is sealed to prevent leakage and to prevent oil from entering the combustion chamber.
    The skirt portion of the piston means of the lower portion of the piston, its role is to keep the piston in the reciprocating movement of the vertical posture, that is, the guide portion of the piston.
    The shape of the piston skirt is very particular about especially like cars light passenger cars, the designers from the structure and performance of the engine, the often brains piston skirt, compact and smooth operation to try to make the engine structure.
    The piston pin is a piston connected via a piston pin and connecting rod supporting portion, located above the portion of the piston skirt. Is unique in that a high-speed engine piston pin pin housing bore and the piston is not necessarily in the same centerline plane can be offset to one side a little bit, namely the work of stroke piston contact with the side of the offset of the cylinder wall, so after the piston to the upper dead point transform direction the piston percussion Gangbi degree reduced, thereby reducing the engine noise.