An engine with a cylinder wall surface pattern providing oil storage

摘要

An internal combustion engine 10 includes cylinders 19 which have a predetermined surface finish providing discrete pockets in the cylinder wall for oil storage. There may be at least two different surface patterns, the first pattern designed to provide a predetermined oil storage volume to lubricate a piston 22 which is slidingly engaged in the cylinder 19, and the second pattern to provide little or no storage capacity for oil. The second pattern is applied to the wall 28 of each cylinder 19 at one or more positions where impingement of un-burnt fuel against the cylinder wall 28 is to be expected. The reduced storage volume of the second pattern reduces the volume of un-burnt fuel that can be transferred from the cylinder 19 to the oil supply of the engine 10. Also disclosed is a method of manufacturing such a cylinder, which may include applying the first pattern by honing and the second and/or first pattern by laser machining.