Magnetic field finite element analysis of concentric biaxial stepped ferrofluid seals

摘要

In order to meet the high cleanliness and high vacuum requirements of the working environment of the silicon conveyer robot, a new type of concentric biaxial stepped ferrofluid sealing structure is proposed based on the original universal ferrofluid sealing structure. The two dimensional simplified physical model of concentric biaxial stepped structure under axisymmetric condition is established by using the magnetic field finite element method. The nonlinear magnetic field distributions in the ferrofluid sealing structure are calculated and analyzed. The influences of the sealing gap, the width of the pole teeth, the ratio of the permanent magnet length to its height on the its sealing capabilities were studied. The calculation results were also analyzed and discussed. The results show that the pressure resistances of the concentric biaxial stepped ferrofluid seals significantly decrease with the increase of the sealing gap. Their pressure resistances firstly increased and then decreased with the increase of tooth width. The pressure resistance of the outer diverging stepped ferrofluid seal in the concentric biaxial stepped ferrofluid seal firstly increased and then decreased with the increase of the ratio of the permanent magnet length to its height; Their pressure resistances of inner converging stepped ferrofluid seal firstly decrease and then increase with the increase of the ratio of the permanent magnet length to its height.