Influence of Liquid Film Thickness on Dynamic Property of Magnetic-Liquid Double Suspension Bearing

Due to the low viscosity of seawater, it is difficult to form the seawater-lubricated film, and the bearing capacity and stiffness of the seawater-lubricated film is very small. It is easily to cause the “overload” and “burning” phenomenon of the seawater-lubrication sliding bearing, and the operation stability and service life can be shorted. The magnetic bearing takes the bearing form of non-contact suspension, and it is more suitable as an auxiliary support to the seawater-lubrication sliding bearing. Therefore, the paper introduces the electromagnetic suspension support into the seawater-lubricated sliding bearing. And then a novel Magnetic-Liquid Double Suspension Bearing with the advantages of electromagnetic suspension and hydrostatic supporting can be formed. The structural characteristics, supporting mechanism, hydrostatic self-adjustment and electromagnetic-adjustment processes of Magnetic-Liquid Double Suspension Bearing can be analyzed in the paper. Based on force balance equation, electromagnetic equation and flow equation, the transfer function of different adjustment processes under constant-flow supply model are deduced. Then adjusting time, dynamic stiffness and phase margin are selected as dynamic indexes. The influence rule of the liquid film on capacity property of single degree freedom bearing system of Magnetic-Liquid Double Suspension Bearing can be analyzed. The results show that as liquid film thickness increases, dynamic stiffness decrease and adjusting time increase, and phase margin remain the same during the hydrostatic self-adjustment process. The proposed research provided a basis for the design of Magnetic-Liquid Double Suspension Bearing in the engineering practice.