Berezovetska O. Substantiation of the parameters of a rotary vacuum pump for milking installations

The dissertation is devoted to improvement of the efficiency of a vacuum system of milking machines by developing a double-rotor vacuum pump with isotropic elastic plates on the rotor ends, which rotate in the lubricating medium. The work presents classification of the vacuum pumps for milking machines by their functional and technical characteristics basing on the analysis of impact of the milking system parameters on the technological process of machine milking, justifies the type and peculiarities of the vacuum pump construction, which secures increase of the efficiency of the milking machine vacuum system. The researcher gives reasons for the rational construction sizes, such as rotor radius, distance between the conventional centers of the two rotor fillets basing on the analysis of operation of a double-rotor vacuum pump for the rotors in the form of a Cassini oval. The thesis presents the obtained analytical dependence of the active area of the pump cross section basing on the normal elliptic integral of the second kind, which sets relations between the construction parameters of rotors, angle of the rotors turning. The conducted theoretical study on the construction and technological parameters of the vacuum pump has confirmed a dependence between them, as well as their impact on the process of air flow, characterizing the quality of underpressure generating. A laboratory installation and vacuum pump were composed to study the coefficient of friction, return characteristics and capacity of the rotor drive with application of tensoresistive sensors. The author suggests a methodology to determine the coefficient of friction with application of water for lubrication of the rotors’ friction surface. For experimental determination of the coefficient of friction, the researcher proposes a methodology and makes calibration of the tensometrical beam. The experimental double-rotor vacuum pump was developed to study the process of underpressure generation, which is a component of the experimental laboratory installation. The dissertation justifies the obtained analytical dependences of the speeds and accelerations of a radial and side flow of the air in the “rotor-stator” system of a double-rotor vacuum pump, which identify relations between the rotor construction parameters, underpressure, equivalent length of a closure, and size of clearance, which serve for substantiation of the construction of a rotor with elastic plates on the rotor ends. Basing on the results of the theoretical and experimental studies, the author of the dissertation determines peculiarities of measuring the coefficient of sliding friction in the medium of a lubricating-cooling fluid under different modes of the vacuum pump operation, identifies the specificity of generating underpressure for milking machines. It is proposed to set isotropic elastic plates using a lubricating-cooling fluid. It contributes to improvement of the efficiency, reliability and sustainability of a vacuum pump.