A magnetoelastic viscometer for on-line monitoring of viscosity of lubricating oils

Abstract

The paper discusses the prospects for developing means for on-line measurement of the viscosity of lubricating oils, including diagnostic instrumentation based on magnetoelastic interaction. The theoretical basis for the development of magnetoelastic sensors and the main concept of measuring the fluid viscosity are presented. Two methods of measuring the viscosity are described. The first method is based on estimating variations in the natural frequency of oscillations of a sensitive element and the second involves analysis of the decay rate of the amplitude of oscillations. The design of the developed magnetoelastic sensor and the experimental results of comparing the two measurement methods are reported. The paper also presents the comparative results of measurement of the oil viscosity by a magnetoelastic sensor, a capillary viscometer, and a solid-state piezoacoustic sensor. It is shown that the reliability of the magnetoelastic sensor is high from the viewpoint of on-line monitoring; owing to its relatively low cost and ease of maintenance, it has wide potential for application in monitoring of lubricating oils in tribosystems.