Determination wear intensity of electrical brushes in DC machines considering impact of collector’s surface

Abstract

One of the most loaded units affecting the reliability of DC machines is the collector-brush unit. There is a continuous process of mechanical, electrical and chemical interaction of the electric brushes with the collector during operation of the DC motor, which increases the wear of the electric brushes. In a result of the analysis of the works, devoted to the study of the operation of the collector-brush unit’s elements, the authors proposed a mathematical model for determining the intensity of wear of electric brushes, which allows taking into account the effect of the collector profile on the electric brushes wear intensity. The basic data and dependencies for modelling the movement of the electric brush on the collector surface, which based on the design scheme, are presented. A distinctive feature of the developed scheme is that the elastic force at the contact of the brush with the surface of the collector is determined from the side of each collector plate. For the above scheme, a system of differential equations is compiled, allowing simulating the movement of the brush in the radial and tangential direction during its interaction with the surface of the collector. The resulting mathematical model allows us to determine the trajectory of the brush and the oscillations of the elastic force that occurs at the point of contact of the brush with the collector, with different parameters of the collector-brush unit’s elements and modes of operation of the machine, causing a certain frequency of rotation of the armature. Taking into account the above mathematical model, a software product has been developed for calculating the wear rate of DC motor electric brushes during its operation. The practical value of the work is that the use of the developed software allows you to find more optimal operating parameters for the collector-brush unit of DC motor with a minimum of time.