Performance Study Of Auxiliary Bearing Based On Four-contact-point Ball Bearing

Auxiliary bearing is one of the indispensable accessories in active magnetic bearing(AMB)systems,which can protect the equipment from damage during the destruction of the AMB.However,an ordinary ball bearing is easily damaged by the giant impact forces produced by the fall of the rotor,while four-contact-point ball bearing(FCPBB)has the characteristics of high limit speed and strong bearing capacity.In this paper,FCPBB is proposed as auxiliary bearing in AMB system,and a series of relevant researches are carried out.Firstly,the design of FCPBB was carried out.Based on the internal structure of the bearing,the force model of a single ball-channel and the friction moment model of the bearing were established.By analyzing the influence of structural parameters on stress strain and friction moment,the selection range of internal structural parameters was obtained.Then the mechanical characteristics of the FCPBB were analyzed and compared with the angular contact ball bearing(ACBB).It was found that the maximum internal stress of FCPBB is smaller than that of ACBB under the same load.Secondly,the dynamic model of rotor dropping was established and the dynamic response of rotor was analyzed.By comparing the protective effects of FCPBB and ACBB,it was found that the maximum stress in the FCPBB is 10.8% less than that in the ACBB.Finally,a test rig was built to carry out the rotor drop experiment under the protection of FCPBB and ACBB.It was found that when the rotor drops on the FCPBB,the impact is more obvious and the range of bouncing is wider,but the maximum internal stress is smaller.The test results showed that the FCPBB is inferior to the ordinary auxiliary bearing in reducing the impact force and restraining the bounce of the rotor,but it has more advantages in improving bearing capacity and life.