Apparatus for sealing a shaft to prevent penetration of particles, comprises an annular stationary sealing device disposed radially around the shaft at the distance of an annular gap, where the annular gap is applied with a magnetic field

摘要

The apparatus comprises an annular stationary sealing device (54) disposed radially around a shaft (50) at the distance of an annular gap (64), where the annular gap is applied with a magnetic field and is filled with a mixture of sealing and lubricant medium (66) and magnetic carrier particles. The sealing and lubricant medium contains oil-graphite mixture, whose oil consists of single oil component. The sealing and lubricant medium exhibits structure-viscous and/or shear-thinning behavior, and is thixotropic liquid. The oil of the oil-graphite mixture is silicone oil. The apparatus comprises an annular stationary sealing device (54) disposed radially around a shaft (50) at the distance of an annular gap (64), where the annular gap is applied with a magnetic field and is filled with a mixture of sealing and lubricant medium (66) and magnetic carrier particles. The sealing and lubricant medium contains oil-graphite mixture, whose oil consists of single oil component. The sealing and lubricant medium exhibits structure-viscous and/or shear-thinning behavior, and is a thixotropic liquid. The oil of the oil-graphite mixture is silicone oil. The sealing and lubricant medium contains components which cause that the viscosity of the sealing- and lubricant medium decreases with a shear force effect to the sealing and lubricant medium. The sealing and lubricant medium has a viscosity of 50000-500000 mm 2/seconds. The mixture of oil and graphite contains 20-40 wt.% of graphite. The mixture of sealing and lubricant medium and magnetic carrier particles contains 40-60 wt.% of magnetic carrier particles. The graphite particles have an average diameter of 5-20 mu m. Independent claims are included for: (1) a developer station of an electrographic printer or copier with a roller; and (2) a method for sealing a shaft to prevent the penetration of particles.