The role of cylinder liner

1. Together with the cylinder head and piston, it forms the cylinder working space;

2. The cylinder liner of the cylindrical piston diesel engine bears the thrust of the piston side and becomes the lead of the reciprocating movement of the piston;

3. Transfer the heat of the piston assembly and itself to the cooling water to make it work at a proper temperature;

4. The cylinder liner of the two-stroke diesel engine is equipped with air ports, which are opened and closed by the piston to realize air distribution.

What are the two types of cylinder liners

Cylinder liners are divided into dry cylinder liners and wet cylinder liners. The distinction between the two is mainly based on whether it is in contact with the coolant.

1. Dry cylinder liner

The characteristic of the dry cylinder liner is that the outer surface of the cylinder liner does not come into contact with the coolant. In order to obtain a sufficient actual contact area with the cylinder block to ensure the heat dissipation effect and the positioning of the cylinder liner, the outer surface of the dry cylinder liner and the inner surface of the cylinder block bearing hole matched with it have a high machining accuracy, and they are generally used Interference fit. The dry cylinder liner has a thin wall, generally only 1~3mm. Dry cylinder liners are often used in gasoline engines, and some small-horsepower diesel engines also use dry cylinder liners.

Advantages: the rigidity of the machine body is large, the center distance between the cylinders is small, the body mass is small, and the processing technology is simple.

Disadvantages: poor heat dissipation, uneven temperature distribution, inconvenient repair, and prone to local deformation.

2. Wet cylinder liner

The characteristic of the wet cylinder liner is that its outer surface is in direct contact with the coolant. In addition, it is thicker than dry cylinder liners. The radial positioning of the wet cylinder liner generally relies on the upper and lower two protruding annular belts with clearance fit between the cylinder block, and the axial positioning uses the lower plane of the upper flange. The lower part of the cylinder liner is sealed by 1 to 3 heat-resistant and oil-resistant rubber sealing rings. There are two types of seals: expansion seal and compression seal.

Advantages: There is no sealing water jacket on the body, easy to cast, good heat transfer, relatively uniform temperature distribution, and the wall thickness is generally 5-8mm. The most important thing is that the cylinder liner can be replaced without removing the engine from the car during maintenance, which is convenient for maintenance. Wet cylinder liners are generally used in diesel engines.

Disadvantages: The rigidity of the machine body is poor, and it is easy to leak water.