Using of cycloidal gear in car selfstarter

Nowadays the car selfstarters of new generation differ from those used so far, which are serial electromotors. The biggest manufacturers of these selfstarters are: Bosch, Valeo, Delco and Hitachi. Their main characteristic property is using of magnetic field from sintered magnets for excitation of selfstarter. The other characteristic property is using of planetary gear. During initial researches, the rub off teeth of ring gear has been often met in investigated selfstarters. This observation motivated the authors of the paper to investigate possibility of replacing of planetary gear by cycloidal gear in selfstarter. The influence of replacement of planetary gear by cycloidal gear upon operating conditions, such as loading and relative velocity in selfstarter bearing and for teeth of pinion - flying wheel gear, is considered in this paper. Also, the loading of elements of cycloidal gear has been calculated. It is difficult to find characteristics of such selfstarters in known literature - so it is necessary to obtain such characteristic by measurement or calculation approximated characteristic, for example, with FEM method. In the paper the approximated characteristic has been obtained for sample Bosch selfstarter. The knowledge of geometry of selfstarter, material properties and of approximated characteristic of selfstarter allows obtaining value of loading and relative velocities of mating parts with use of elaborated FEM model. For calculation the helping mathematical models have been used. The results of computation and the picture of wear of any selfstarter parts are presented in the paper.