Drag torques of gearboxes are an important part of the overall losses in today's vehicle drive trains. From measurements it is well known that overall drag torques of vehicle gearboxes vary significantly over the range of operating points and speeds, depending on the interaction of the losses of the single gearbox elements like bearings, gearings, etc. Because today's vehicle emission regulations are becoming stricter and stricter "drag torque design" of gearboxes will be even more important in the future. Prediction of losses helps to save cost (e.g. drag torque measurements), speeds up the development and allows to assess many concepts in short time. We collected detailed semi-analytical drag models for the common gearbox components from literature and from manufacturer information and implemented them in a Modelica library. This library contains models for radial shaft seals, rotary unions, synchronizers, multi-disc clutches, helical gearings, planetary gearings, various kinds of bearings, lubrication systems and lubricant characteristics. Using this library drag torques of any vehicle gearbox may be computed for any operating condition (engaged gear, speed, torque, temperature). Simulation results for a 7 speed double clutch transmission show good correlation with measurements.
For a certain class of applications simulation models are developed and then rolled out for standalone usage without the tool with which they have been developed. The user is intended to perform simulation runs, to inspect results, to change selected parameters within given bounds, but not to inspect or even change the model itself.The reasons for such a usage scenario are manifold: The simulation is intended to be used as a black-box tool by non simulation specialists, a component vendor (electric drives, pneumatic or hydraulic components, etc.) likes to demonstrate the performance of his components in the context of a simulation or the model developer may hide model details. If a model development tool includes code generation the model specific simulator can be setup fully automatic. However, a GUI (graphical user interface) for such a simulator must be developed manually. We developed a tool which automatically generates a simulator GUI from a Modelica model and data definition.
The goal of the A2015 library presented in this paper is to develop a Modelica based, tool-independent standard for electromechanical actuators (EMA). This will contribute to the establishment of a "common language" throughout the development of EMAs for aircraft and helicopters and through the supply chain. All stages of the design and validation process (conceptual design, specification, development and validation) are covered. The modeling approach addresses specific aspects of the EMA design process not covered by existing tools. The library scope, engineering need and implementation are described. Modeling of selected EMA components is discussed in more detail. An application example of the library is given (linear actuator, A320 aileron)
Replacing hydraulic primary flight control actuators by electromechanical actuators imposes the problem of reduced reliability. This problem may be overcome by using redundant actuators what in turn increases the system complexity. The appropriate redundancy level and component mapping must be assessed. In specific failure cases the system must be reconfigured in order to maintain the specified performance level to meet aircraft safety regulations. The assessment of the system's reaction upon such kind of scenarios is however a complicated task and must be supported by modeling and simulation. Therefore, modeling and simulation of such a faulttolerant electromechanical system in Modelica is described in this paper. Sample simulation results are presented and discussed.
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