Method of the unbalanced rotor critical frequency overcoming by means of the operated magnetic spring

Alexey Lukin,Lev Shtukin,Dmitry Skubov,Ivan Popov,M Belhaq

doi:10.1051/matecconf/20141603005

Abstract

When passing critical rotational frequency of a rotor with significant imbalance there can be cross- oscillations with large amplitudes. The algorithm of critical rotational frequency overcoming which allows reducing these oscillations considerably is described.It is offered to use a differential magnetic spring as an elastic support with operated stiffness. When passing critical rotational frequency of a rotor with significant imbalance there can be cross-oscillations with large amplitudes. The algorithm of critical rotational frequency overcoming which allows reducing these oscillations considerably is offered. For this aim it's proposed that elastic supports have two stiffness coefficients: working and increased, with the corresponding two values of critical frequency. It is offered to use a differential magnetic spring as an elastic support with operated stiffness. The magnetic spring consists of the permanent magnets connected by mag- netic conductors. The schematic diagram of a differential magnetic spring is shown in Fig. 1.

Highlights

The magnetic support contains three permanent magnets, side magnets are fixed and the middle one, which is connected with the shaft train, can move in the vertical direction, and is itself established on the amortized support
Its important advantage is capability to change the equivalent stiffness of an elastic support. It allows to operate the value of stiffness during the rotor acceleration so that to achieve reduction of oscillations amplitude, and, stresses in the supports up to the acceptable values even at big imbalance and to provide the acceleration to the over-critical frequency of rotation
Let the frequency at A point correspond to an operating mode, and the support stiffness at an operating mode correspond to the characteristic No.1 (Fig.3)

Summary

Introduction

The magnetic support (spring) contains three permanent magnets, side magnets are fixed and the middle one, which is connected with the shaft train, can move in the vertical direction, and is itself established on the amortized support. Numerical and analytical researches are necessary for the analysis of such nonlinear dynamic system, as a result of which its characteristics corresponding to various criteria such as the minimum time of transition to the operating frequency or the minimum of the oscillations amplitude, etc., should be received.

Results

Conclusion