Composition Of Piston

The piston top is a component of the combustion chamber and is often shaped differently. In gasoline engines, the piston top is often flat or concave to make the combustion chamber structure compact, with a small heat dissipation area and a simple manufacturing process. The convex piston is commonly used in two-stroke gasoline engines. The piston crown of diesel engines is often made into various pits.
The piston head is the part above the piston pin seat, and the piston ring is installed on the piston head to prevent high temperature and high pressure gas from entering the crankcase, and to prevent oil from entering the combustion chamber; Most of the heat absorbed by the top of the piston also needs to be transferred to the cylinder through the piston head, and then through the cooling medium.
The piston head is machined with several grooves for installing piston rings, and the number of piston rings depends on the sealing requirements, which are related to the engine speed and cylinder pressure. High speed engines have fewer rings than low-speed engines, and gasoline engines have fewer rings than diesel engines. Generally, gasoline engines use two gas rings and one oil ring; The diesel engine has three gas rings and one oil ring; Low speed diesel engines use 3-4 gas rings. To reduce friction losses, the height of the ring should be minimized as much as possible, and efforts should be made to reduce the number of rings while ensuring sealing.