Research On Support Characteristic Of Auto-Eliminating Clearance Auxiliary Bearing Devices

The auto-eliminating clearance auxiliary bearing(ACAB)is a device that is capable of automatically eliminating the gap between the rotor and the auxiliary bearing after the failure of the magnetic bearing,and has the advantages of high reliability,long service life and etc.The auxiliary bearing needs to temporarily support the rotor with high rotational speed.And the supporting characteristics of ACAB directly affect the dynamic characteristics of the "auxiliary bearing-rotor" system.Focusing on the key problems of the ACAB such as structural uncertain,the fact that traditional bearings identification methods only suitable for low-speed rigid rotors,this dissertation studied the following aspects.Firstly,aiming at the problems that the theoretical identification method of the rotor support parameters is subject to the frequency characteristics of the control system and the problem of identification accuracy,the support parameter identification method based on the rigid rotor model is studied,and the support stiffness and damping matrix of the ACAB are deduced.The simulation analysis pointed out that the parameter identification method is only applicable to the working condition that the rotational speed of the rotor is lower than its first-order critical speed.Then,based on the limitations of the identification method of rigid rotor model,the support parameter identification method based on the finite element method is studied,and the support parameter identification of the ACAB is realized when the rotor is above the critical speed.On this basis,the ACAB support parameter identification method based on finite element method is improved,which solves the problem that the rotor with residual unbalanced quality will affect the identification results.Furthermore,the dynamic support characteristics of the ACAB are studied experimentally.Taking into account the residual unbalanced mass of the rotor itself,the identification method based on finite element method is used to realize the experimental identification of the support parameters of the ACAB.The experimental identification results are verified by comparing to the unbalanced response data.Finally,according to the non-linear contact characteristics of the ACAB,a method of identifying the static stiffness of the ACAB by optimizing the normal contact stiffness factor is proposed.The relationship between the support static stiffness and the normal contact stiffness factor of the ACAB is analyzed,and the feasibility of the method is verified by the static stiffness experiment of the ACAB.The results show that the error between the experimental static stiffness and the simulated static stiffness under the optimal normal contact stiffness factor is 3.74%.