IMPROVING THE RELIABILITY OF ASYNCHRONOUS ELECTRIC MOTORS FOR AGRICULTURAL PRODUCTION BY IMPLEMENTING MAGNETIC SEALING TECHNOLOGIES

Abstract

Improving the reliability of agricultural equipment is an urgent task. From these positions, it is important to consider the operation of asynchronous motors (AM). These electric motors are used in severe operating conditions and have a fairly high accident rate. One of the ways to extend the operational cycle is to almost prevent the pollutants penetration completely inside the AM. It is possible to ensure the required level of tightness by using a new type of seal – magnetofluid seals. The purpose of this work is computer modelling and the spatial distribution study in the active region of the rotating shaft seal of the magnetic field, magnetic forces acting on micron-sized magnetic particles, as well as the velocity of magnetophoretic motion of particles under the action of these forces. The numerical finite element method implemented in the Comsol software package is used in this work. The following main results were obtained in this work. The finite-element calculation of magnetic induction distribution in the active zone of the seal with an increased gap (0.8 mm) for two cases – 1) when the rotating shaft is smooth and 2) in the presence of a defect on the shaft has been performed using the Comsol program. For the first time analytically considered the mode when additional magnetic particles of micron size are added to the working magnetic fluid according to the patent of Ukraine № 10642. The distribution of zones characterized by maximum local inhomogeneity of this field determining the magnitude and direction of the magnetic force acting on microscopic particles in magnetic fluid is shown. The distribution of magnetic force acting on microparticles of different diameters (0.1–10 microns) and the velocity of motion of these particles under the action of this force is obtained by calculation. It is shown that these particles concentrate in zones with inhomogeneous field – in the angular zone of the teeth of the magnetic system and near the defect on the shaft, and the characteristic time of the transient process for particles with diameters of 0.1, 1 and 10 microns is 630, 6.3 and 0.063 min, respectively. The addition of micron particles to the working gap of the seal allows it to increase up to three times the value of this gap while maintaining reliability in operation. The performed calculation showed the possibility of application of the technology according to the patent of Ukraine № 10642. Implementation of MFS with increased gaps proved the adequacy of the developed mathematical model.