Dynamic responses after rotor drops onto a new-type active eliminating protective clearance touchdown bearing

A new-type active touchdown bearing (TDB) system integrated with a centering device to eliminate the protective clearance after rotor drop in an active magnetic bearing (AMB) system is proposed. A rotor dynamic model is established on the basis of rigid rotor theory. A collision model between the support base and outer race of the ball bearing and a real-time ball bearing elastic supporting force model are established on the basis of Hertz contact theory. The dynamic model of the new-type TDB is established on the basis of vibration theory. Using these established theoretical models, the dynamic responses after rotor drops onto the new-type TDB are simulated and compared with the responses after rotor drops onto traditional TDB. Relevant experiments are conducted on an AMB test platform to verify the simulation results. The results show that the proposed new-type TDB can rapidly eliminate the protective clearance after rotor drop and can thus effectively reduce the following rotor vibrations and impacts.