Oil scraper ring for pistons of internal combustion engines

摘要

The invention relates to an oil scraper ring for pistons of internal combustion engines, said oil scraper ring comprising a disc ( 1 ) provided with a bearing surface (h) having an asymmetrical crowned form with a vertex line ( 3 ) extending over the periphery of the disc. Said disk ( 1 ) is arranged in a ring groove ( 7 ) of the piston and respectively has a ring groove side ( 6 ) opposing the piston head and a parallel ring groove side ( 5 ) facing the piston head. The aim of the invention is to achieve an improved oil scraping action compared to that of prior art, while reducing the friction and the abrasion of the bearing surface. To this end, the disk flanks ( 2, 2 ') extend radially outwards to the bearing surface (h), at an angle (A), in a convergent manner, in such a way that when the flank is placed on the ring groove side ( 5 ) facing the piston head, the disc is only in contact with the cylinder wall ( 8 ) with the vertex line ( 3 ) thereof, and when one of the disc flanks is placed on the ring groove side ( 6 ) opposing the piston head, the disc is only in contact with the cylinder wall with a first section (I) of the bearing surface (h) thereof. The cross-section of the bearing surface (h) of the disc ( 1 ) is characterised by: a first section (I) having an asymmetrical form following a second degree polynominal with the formula h(x)=ax+bx², wherein x represents bearing surface co-ordinates in the cartesian co-ordinates system in mm, and a, b represent coefficients where a is defined by the ratio of the axial flank play of the discs to the width of the disks, and b is defined as the value of the bearing surface curvature; a carrying vertex (II) h(x=0) embodied as an edge; and, a third section (III) of the asymmetrical form following the function h(x)=cx², where c is a multiple of b.