Design of an electromechanical rotative damper prototype for automotive applications

The main objective of this thesis project is to design an electromechanical rotative damper for automotive applications: in particular the work is focused on the design of the gear transmission stage and then on the development of the damper actuator assembly to realize a prototype for bench testing. A preliminary analysis of the state of the art of rotative dampers gives some hints on possible solutions concerning the assembly, the gearbox and the leverages. The first design phase is concerning the gearbox: on the base of a previous study, the configuration selected is a double stage planetary gear set. The dimensioning of the planetary stage is performed with KISSsoft software: the target of the optimization is to minimize the size of the gears while keeping acceptable values of safety factors. In these calculations, different loading conditions are considered: besides the constant input, a more realistic load spectrum is defined by simulating road profile irregularities. Once the macro-geometry of the gear set is defined, the work is going on with the design phase of the damper actuator assembly: it includes the gearbox stage, the electric machine and the leverage system. The 3D model of the damper assembly is built in SOLIDWORKS: starting from the planetary gear set defined in KISSsoft, the design is focused mainly on the shafts and planetary housing. The study of the gear shafts is integrated with the analysis of the gears (KISSsoft) in order to minimize stresses and deformations and evaluate their reciprocal effects on the gears life. The external housing of the actuator is designed to be fitted on a customized test bench: this allows to experimentally evaluate the performances in a future phase of the project. Nonetheless, in the design phase the evaluation of performances is performed thanks to simulations and software computations, taking into account three main parameters: efficiency, mass and inertia, noise level. The gearbox efficiency is computed on the KISSsoft model. The equivalent inertia added to the suspension motion is computed starting from the rotational inertia of the damper and then transformed into linear equivalent mass. The evaluation of noise level is obtained by building a new model in COMSOL and by performing some FEM acoustic simulations. Finally, even if this thesis work is oriented to the prototype phase, anyway a preliminary analysis of the issues concerning the real suspension architecture is carried out. In particular, the feasibility of the proposed leverage solutions is investigated, a first model of input arm is defined and then a possible positioning of the damper device inside the suspension architecture is analyzed.