What is a cylinder liner?
It is a cylinder that is fitted to the engine block to form the cylinder, and is one critical function part that forms the engine interior.
In Japan they are usually called Cylinder Liners, but some countries (companies) call them Cylinder Sleeves.
3 functions of Cylinder Liners
Function 1 Form the sliding surface
Tightly holds when the valve is seated, prevents compressed gas or combustion gas leaking into the manifold from between the valve and Valve Seat.
- High burn resistance
- Low self-friction
- Low friction with the piston ring
- Low lubricating oil consumption
Function 2 Heat conduction
Reduces vale and cylinder head friction at the same time.
Function 3 Keep airtightness
Prevent compressed gas and combustion gas leaking out. The liner should not be prone to deformation due to the high pressure/high temperature inside the cylinder.
The engine's cylinder wall is high temperature/high pressure, and the piston ring/piston is sliding at high speed, and particularly with truck/bus engines a long-life is demanded, so we use highly friction resistant casting material Cylinder Liners only for cylinders. Also, in recent years, to make engines light-weight, engine blocks are changing from casting to aluminum alloys, however, aluminum alloys suffer deformation and friction during direct sliding when used for the cylinder inner circumference, therefore, the aluminum die cast block is mainly used where the Cylinder Liner is cast-in.