Cylinder liner structure

The inner surface of the cylinder is easily worn due to the action of high temperature and high pressure gas and contact with the high-speed moving piston. In order to improve the wear resistance of the cylinder and prolong the service life of the cylinder, there are different cylinder structures and surface treatment methods. There are three types of cylinder structure: no cylinder liner type, dry cylinder liner type, and wet cylinder liner type.
The cylinder-free body is a body without any cylinder liner, and the cylinder is directly processed on the body. The advantage is that the center distance of the cylinder can be shortened, and the size and quality of the body can be reduced. But the cost is higher.

The dry cylinder liner is not in contact with the coolant, the wall thickness is 2~3mm, and the outer surface and the inner surface of the cylinder liner seat hole must be finished to ensure the necessary position accuracy and facilitate disassembly and assembly. The advantages are that the rigidity of the body is large, the center distance of the cylinder is small, the weight is light, and the processing technology is simple. The disadvantage is that the heat transfer is poor, the temperature distribution is uneven, and local deformation is prone to occur.
The outer wall of the wet cylinder liner is in direct contact with the coolant, and the wall thickness is 5~8mm. The upper and lower positioning rings are used to achieve radial positioning, and the axial positioning is achieved by the cooperation between the upper flange of the cylinder liner and the corresponding supporting surface on the top of the body. The advantage of wet cylinder liner is that there is no sealing water jacket on the body, easy casting, good heat transfer, relatively uniform temperature distribution, convenient repair, and the cylinder liner can be replaced without removing the engine from the car. The disadvantage is that the rigidity of the body is poor and it is easy to leak.