Riassunto analitico
The aim of the thesis and the project activity that I have done in collaboration with ZF Friedrichshafen AG (Ostellato) is the development of a lumped parameter dynamic model of an internal gear pump, which can be implemented in active suspensions vehicle. The problem is developed with the aid of graphical programming and programming language environments, like Simscape and MATLAB. They allow simulating and analysing multidomain dynamical systems, manipulating matrices, plotting functions and data in a closely connected environment.
The preliminary model of the circuit is developed in Simscape; through its tools and library, the complete hydraulic system has been built, identifying the main subsystems and key components. The further simulations, in working condition, have provided the results in terms of pressure differences at the main orifice and torque of the pump; this information have to be compared with experimental testing in order to evaluate their accuracy and characterize the dynamic conditions. A parameter sensitivity analysis is implemented at the same time, which takes into account possible variations of the fluid properties during real life applications.
Once the main circuit is characterized, the activity focuses on the study of the internal gear pump in MATLAB environment. The primary objective is to model the pump operation with a lumped parameter system. It has to permit an evaluation of the efficiency of design modifications on teeth, grooves, clearances and working conditions. The work flow starts with teeth drawing and grooves import from CAD; once the gear wheels are defined, it is possible to determine the fundamental geometric quantities, such as volumes, outflow areas and clearances as a function of wheels position. The previous steps compose the pre – processing phase, which is preparatory for the resolver; the evaluation of pressure field and forces is done through a differential equations iterative procedure solver.
|
