【作者】

Johann Nagl

【摘要】

该论文已在赫尔辛基举行的第28届CIMAC世界大会上发表，论文的版权归CIMAC所有。 Technical demands for journal bearings in combustion engines are highly varied, and often in contradiction to each other. Requirements are resistance to wear, fatigue, corrosion, cavitation; sufficient emergency run and smooth running-in behaviour. Further challenges may arise from manufacturing and operational environment. Adaptability to manufacturing tolerances as well as insensitivity to original dirt and foreign particles is required in applications as well as robustness to operation and the possibility to perform bearing changes directly in the field. Driven by IMO Tier III regulations ongoing trend towards higher fuel efficiency and increased power density in diesel, gas, and dual-fuel engines, accompanied by increasing peak oil film pressures and simultaneously a reduction of minimum oil film thickness, put ever increasing demand on materials used for bearings, approaching the performance limits of conventional products. The strengths of state-of-the-art bearings are divided – while journal bearings with standard sputtered overlays provide the highest load carrying ability they are vulnerable to dirt, whereas conventional electroplated bearings offer high tolerance to foreign particles at the cost of reduced life time and wear resistance. This paper will present the recent development of journal bearings for high and medium-speed diesel, gas and dualfuel engines combining the robustness and dirt tolerance of conventional electroplated three-layer bearings with the wear resistance, and longevity of standard sputter bearings. This is achieved by a leaded or lead free bronze lining with a tin-based sputtered overlay consisting of a conforming, ductile matrix as the main component, containing a loadcarrying structure of hard particles to provide the necessary mechanical strength required for loaded bearing shells. An overview of rig testing results for wear resistance at medium and high speeds as well as for dirt shock tolerance will be given in comparison to standard bearings, complemented by results from engine tests of prototype bearings. Additional development aspects for adaptive journal bearings will be discussed, addressing measures to further prolong the service life and field performance of journal bearings. Such are advancements of the development of electroplated overlays for bearing diameters up to 450 mm, combining high strength tin based materials with extremely soft micro-alloyed running in layer. Such materials proved to show excellent ductility while massively increasing fatigue strength. We will further present material design of tin-based overlays that allows for gradual hardening of initially soft and conforming overlays during engine operation. Such an approach can provide the required adaptability during the run-in and will subsequently gain mechanical strength further extending service life.

【会议名称】

第28届CIMAC会议

【会议地点】

芬兰 赫尔辛基

【下载次数】

3

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