Compression rings of low-speed high power engines

The paper describes the design of compression rings used in low-speed, high power marine engines and it analyses relations between the most important operational parameters. Ring material, dimensions, geometry of sliding surfaces, distribution of circumferential pressure as well as operational conditions (thermal and mechanical loads, way of lubrication) were taken into consideration for the analysis mentioned above. Moreover, the paper points at modifications in ring geometry that have been happening for last years, comparing previous and recent designs. The effect of ring circumferential pressure against liner on the piston-cylinder assembly operation has been considered and the causes of its variability have been pointed out as well. When presenting the methods of measurement and tangential force calculations basic advantages and disadvantages have been presented as well as the evaluation of changes resulting from the ring circumferential wear. The compression ring mathematical model developed by the authors allows for a precise definition of relations between ring geometry and distribution of ring circumferential pressure. A need for a more accurate method of ring circumferential pressure evaluation has been justified in summary, giving hints necessaryfor its preparation.