Cylinder blocks

Cylinder blocks

The cylinder block is a fixed, integral part of the crank mechanism (hereinafter referred to as KM), which combines the engine cylinders. It is made by casting from cast iron. Sometimes the cylinder block is cast from cast aluminum as well as magnesium alloys. In the cylinder block, the crankshaft is mounted on special supporting surfaces. The upper part of the cylinder block is closed by the cylinder head. And the crankcase is attached to the bottom of the cylinder block. The cylinder block is the main engine part to which other engine parts are attached.

Cast iron and Aluminium cylinder blocks

Engines with a cylinder block have a water (liquid) cooling system, and the cavities through which the coolant circulates are called the engine cooling jacket.

Cylinder block and cylinder liner material

Depending on the working volume and other technical and operational characteristics, purpose, there are several layout options (arrangement of engine cylinders), as well as several materials for the manufacture of the block and cylinder.

Since the conditions of varying pressures arise in the cylinder above the piston cavity, the inner surface of the cylinder walls is in contact with the flame and hot gases (the temperature of which is from 1500–2500 ° C), such a part must be made of high-strength materials with high mechanical strength. The sliding speed of the piston rings on the cylinder walls is quite large from 12 to 15 m / s, so the inner walls of the cylinder must have increased stiffness.

In this case, the service life of the cylinder (cylinder liner) will increase and the part will be more resistant to various types of wear (abrasive, corrosive and erosive). If the surface of the cylinder block has worn out above acceptable limits (as determined by the cylinder block defect method), it is necessary to repair the cylinder block.

If there are no restrictions on the mass of the engine, for example a tractor engine, then the cylinder block is made of pearlite cast iron.

On transport engines, where there are weight restrictions, I use lighter aluminum and magnesium alloys for the manufacture of cylinder blocks.

Advantages of gray cast iron cylinder blocks:

  • low cost;
  • high manufacturability of casting;
  • stability of material properties;
  • the ability to repair block cracks (by sealing, welding, epoxy glue);
  • high hardness and rigidity of surfaces, resistance to overheating;

Cast iron cylinder blocks shortcomings

The main disadvantage of cast iron is its large mass (density 2.7 times higher), and lower thermal conductivity. Aluminum cylinder blocks Aluminum alloys are more expensive, but aluminum cylinder blocks have a much lower mass. Aluminum alloys have a number of features that should be considered when manufacturing and operating cylinder blocks.

Author: delfi

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