The two stroke crosshead low speed diesel engine has been a preferred prime mover in the merchant marine for mostly a century. Although its basic working principle has not been changed, the demand for still higher power, produced at the lowest possible fuel consumption, from a machine occupying a minimum of space, has constantly increased the demands to its three principal bearings, main bearing, crank pin bearing, and crosshead bearing, This paper deals with design techniques for bearings as applied in modern large two stroke diesel engines. Simulation methodology as well as design verification techniques by measurements are described. Most important, the actual design features, as developed using the illustrated techniques, are shown. Calculation results from in house simulation software including advanced combinations of loadgeneration and Elasto Hydro Dynamic (EHD) analysis are demonstrated, in particular for a newly developed main bearing assembly, and for the Blended-Edge (BE) main bearing applied in MAN B&W two stroke diesel engines. Also simulation results for the wide pad crosshead bearing, which has been introduced in the ME-B engine series, are given. Major design particulars, bearing application range, and service experience are illustrated in each case. The actual geometry of a bearing journal, even when produced within strict tolerances of cylindricity, may strongly influence the distribution of hydraulic pressure in the oil film. A method of in situ measuring the shape of a main bearing journal in detail is presented, and the influence of typical imperfections discussed. Measurements of the oil film thickness of the main bearings during full operation, made on the 4T50MX test engine in Copenhagen, are shown in correlation with the equivalent simulation results, and illustrating the development on the main bearing components. In parallel with the mechanical/geometrical development, also the issue of material properties are addressed. Traditionally Babbitt has been the preferred bearing material for a number of reasons. However stronger Tin-Alu bearings have also been used for decades. MAN B&W diesel engines use both type of materials, and recent developments aim at merging best properties for both type of materials in one. MAN has worked on this development for well over four years now, and the first service trials are presented.


    Zugriff

    Zugriff über TIB

    Verfügbarkeit in meiner Bibliothek prüfen


    Exportieren, teilen und zitieren



    Titel :

    Recent development in analysis and design of principal bearings of large two stroke diesel engines


    Beteiligte:


    Erscheinungsdatum :

    2010


    Format / Umfang :

    17 Seiten, 42 Bilder, 1 Tabelle, 4 Quellen


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Datenträger


    Sprache :

    Englisch




    Development of large four-stroke diesel engines

    Lassberg, D. | Tema Archiv | 1976


    Recent Experience and Developments in Bearings for Diesel Engines

    Conway-Jones,J.M. / Pratt,G.C. / The Glacier Metal,US | Kraftfahrwesen | 1977


    Lubrication of small end bearings in supercharged two-stroke diesel engines

    Napel,W.E. / Akker,M. / Bosma,R. | Kraftfahrwesen | 1982


    Bearings For Turbocharged Diesel Engines

    Pfestorf,H. / Karl Schmidt,Neckarsulm | Kraftfahrwesen | 1980


    Two-stroke diesel engines

    Grecchi, A. | Engineering Index Backfile | 1923