The Basic Knowledge of Piston
Engine is like a car's "heart", but the piston can be understood as is the "center" of the engine. In addition to living in harsh working environment, it is the busiest one in the engine, constantly engaged from the bottom dead center to the TDC, suction, compression, workmanship, exhaust.... The interior design of the piston is emptying, more like a hat. The both ends of the hole are connected with the piston pin , which connects the smaller head of the connecting rod, and the bigger one of the connecting rod is connected with the crankshaft. Under this assembly, the reciprocating motion of the piston is transformed into the circular one of the crankshaft.
There are three lines at each piston skirt, it is with the purpose of installing two gas rings and an oil ring, and the gas ring is top loading. In the assembly, the opening of two gas rings need to be stagger so that they have the sealed effect. The main role of the oil ring is to scrape the excess lubricating oil splashed on the cylinder wall. At present, the widely used material of the piston ring mainly has the high quality gray iron, ductile iron, alloy cast iron, etc.
In addition, due to the different position of piston ring , the surface treatment they use it is different, too. The external circular surface of the first piston ring is usually processed by chrome or spraying molybdenum, which the main function is to improve the lubrication and abradability of the piston ring. Other piston rings are mostly processed by tinning or phosphatization in order to improve its abrasion resistance.
If the piston ring is improperly installed or sealing is not good, it will cause that oil on the cylinder wall flow into the combustion chamber and burn together with the mixing gas, that is the phenomenon of burning oil. If the clearance between the piston ring and cylinder wall is too small or the piston ring was jammed in the ring groove for carbon deposition, the cylinder wall probably will be scratched when the piston is doing the reciprocating movement. Besides, it will form very deep grooves on the cylinder wall after a long time, which is often said that the " cylinder scoring " phenomenon. Cylinder wall with grooves, bad sealing, also can cause burning oil. Therefore, it should be regularly check the working condition of the piston and ensure the operation of the engine in good condition.