Reduction of the maximum contact stresses by changing geometric parameters of the trochoidal gearing teeth profile

The primary goal of the analysis presented in this paper is to define conditions that would enable reduction of the maximum contact stresses by changing geometric parameters of the trochoidal gearing teeth profile. One of the basic problems in designing the internal trochoidal gearing is the impossibility to compensate for the wear that is the result of high contact pressures in some meshing phases. In order to define maximum contact stresses, forces and moments were analysed using analytical and numerical methods, taking into consideration the pressure variation in the pump chambers due to the fluid flow. It has been shown that gear pairs can be generated based on minimizing the equivalent curvature of the profile of the tooth in contact, when the condition that the specific slidings of the meshing profiles are equal is fulfilled. This procedure has been applied to a commercial pump, and the obtained solution has been proposed as a better solution for the given conditions. The analysis results have shown that, for the same working conditions, significant reductions in maximum contact stresses can be achieved. For the same teeth number, when the value of the parameter λ is decreased, the maximum contact stress can be reduced by about 16.8 %, while for the smaller number of teeth, with an increase in the value of the parameter λ, approximately 35 % lower values are obtained compared to the commercial pump. The results obtained in this paper have wide and practical application especially in design of gerotor pumps with better performance characteristics.