MAGNETIC FLUID SEAL APPARATUS FOR A ROTARY SHAFT
A single pole piece magnetic fluid seal apparatus which includes a shaft sleeve (18) having magnetic properties attached to and surrounding a shaft element (20) to be sealed. The apparatus also includes a single pole piece (14) surrounding the shaft sleeve, proximate to and in non-contacting relationship with the shaft sleeve so as to define a radial gap (22) between the pole piece and the shaft sleeve. The single pole piece includes first and second annular elements (30N, 30S) attached by a cross piece consisting of a third annular element, wherein the first, second, and third annular elements define an annular channel (34) therebetween. The apparatus also includes at least one magnet (36) located within the annular channel and magnetic fluid (28) disposed in the radial gap to provide a seal between the shaft sleeve and the pole piece. The magnet and the single pole piece provide a magnetic flux path through the pole piece, magnet, magnetic shaft sleeve, and magnetic fluid.