1 Cylinder Design Cylinder Liner (Barrel) Design The liner functions both asa structural membera bearing surface for the piston and ringsMaterialCast Iron for wet linersSteel for dry linersDry liners are inserted into wet linersOnly Wet Liners are normally used in large Diesel Engines
4 Cylinder Design In passenger car engines and small industrial engines Liner is cast integrally with the jacket structureWorn-out bore surfaces may be refinished to a larger diameter, and over-sized pistons are inserted.For long-life industrial and commercial useSeparate removable cylinder liners are usedRepair and replacement is possibleAppropriate materials can be usedcast iron is preferredsteel is occasionally used
5 Cylinder Liner Loading The liner thickness may be calculated fromtl = Liner thickness (m)sc= Permissible cicumferential stress (kN/m2)Pmax= Maximum combustion Pressure (kPa)D = Inner liner Diameter (m)sc = ( ) x 105 kN/m2 for steelsc = ( ) x 105 kN/m2 for cast irontl = tl1 + tl2 for composite dry linerststeel > 2 mm
9 Advantages of Wet Type Liners It can be removed and replaced with great ease and without the need for any special tools or equipment.It is possible to provide for a high-velocity water circulation around the liner and therefore reduce the piston temperature.Since the liner is held only by a flange at the top end, it is free to expand without any restraint.
10 Advantages of Dry Liners Suitable when cylinder block and crankcase are formed in one piece with detachable cylinder headsCooling water can come nearer to the top end of the linerNo gas or water joints are requiredStiffness of the cylinder block is increasedMain DisadvantageA dry liner must be pressed or shrunk into the cylinder barrel.It is difficult to remove or replace without special equipment
11 Lcen/D = 1. 20 - 1. 28 for SI engines Lcen/D = 1. 25 - 1 Lcen/D = for SI engines Lcen/D = for CI engines
12 Liner Flange Design Calculation Taking moments around A ;Section Modulus of thecross-section between B&C ;
13 Design Notes on Water Cooled Cylinder Blocks Walls are tensioned by the gas forces transmitted to the studs via the cylinder headTensile forces are only applied to the walls of the water jacket and the partitions between the cylindersIn-Line and V-Engines with water cooling usually have cylinders cast integral with the upper half of the crankcaseMain casting forming the cylinder block and crankcase may be made from alimimium alloy.
14 Design Notes on Cylinder Blocks The crankcase width is determined from the trajectory of the extreme point of the connecting rod bolt head.Minimum distance between bolt head and internal surface of crankcase is mmWall ThicknessesCast-Iron crankcase walls and partitions are mmCast-Iron water jacket thickness : mmAluminium casting thicknesses are mm more.Die-cast Aluminium thickness is less than cast-iron
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