Exemplary gear calculation of a modern vessel drive train Modern methods of gear calculation applied to an thruster drive train of a research vessel

摘要

Increasing requirements to modern vessels concerning performance and manoeuvrability led to very complex drive train designs. Therefore azimuthing thrusters became very common in the area of offshore supply vessels, tug boats and specialized research vessels. In order to extend the already huge field of operation and to better understand dynamic effects in such azimuthing thrusters the research project "EraNet HyDynPro" was started. The project focuses on the design of a robust drive train which contains a bevel gear stage. Therefore loads caused by propeller-water-interactions as well as loads while operating under ice conditions will be analysed. Based on this interdisciplinary project a contemporary way of gear calculation will be shown in this paper. For gear calculation it is necessary to acquire design loads. These can be measured at high costs or be simulated numerically. In the last few years the Multi-Body-System (MBS) Simulation got more and more popular to determine static and dynamic properties of large drive trains. This simulation can contain mathematical models of the propeller behaviour inside the water and under ice conditions as well as models of the electrical motor. Based on this a good prediction of gearing loads is possible. By the knowledge of the gearing load time series a complex tooth contact analysis can be made for every arbitrary point in time using specialized gearing software. Gear tiltings are considered in order to calculate the load distribution on the tooth flanks. By this knowledge a local comparison of the load and load capacity can be carried out. But how to handle the vast variety of load situations during different load cases and long time series? Therefore an appropriate classification of the different occurring states of gear deviations and gear loads will be presented. This way we are able to determine the risk of common gearing failures like pitting and tooth root breakages in detail for individual drive trains under different operating conditions. The paper will present the procedure of this contemporary way of designing gears. By using a simple spur gear set the general idea of simulating the operating conditions of a drive train and the subsequent complex tooth contact analysis will be explained.