Plunger piston for internal combustion engines

摘要

A piston for internal combustion engines, which has inclined surface portions in the skirt area to allow formation of hydrodynamic wedges of lubricant, these surface portions being constructed as skirt recesses (13 or 14) which are open either towards the upper or towards the lower end of the piston skirt. The transition zone from these skirt recesses to the bearing surface of the working surface of the piston is constituted by oblique surfaces which are inclined inwardly from the surface of the skirt. The oblique surfaces terminate in a circumferential direction within the bearing surfaces of the piston. The oblique surfaces constitute ramps on which a hydrodynamic wedge of lubricacting oil can form. The particular advantage of disposing the oblique surfaces in skirt depressions which are only open at one end lies in that when the hydrodynamic wedge of lubricating oil builds up as a result of the translatory motion of the piston, the oil which forms the wedge of lubricant cannot escape in a peripheral direction which thereby increases the frictional quality (or aqua-planing effect) between the working surfaces of the piston and cylinder.