Ferrotec Corporation

Other

Heiichi Unozawa

Akira Yamamura

Noboru Yamazumi

Hirohisa Ishizaki

A magnetic fluid is held by a magnetic field in a stationary state and by a centrifugal force during rotation, leaking and splashing of the magnetic fluid caused by the instability of the pumping of a dynamic pressure bearing are prevented without using a magnetic fluid with a high saturation magnetization value, and the service life of the dynamic pressure bearing is extended. For this purpose, a sleevehaving a protruding tubular section is fitted and fixed to the outer periphery of the shafthaving a thrust plateformed in an axial vicinity so as to be rotatable relatively to the shaft, an annular coveris formed outwardly from the thrust platein an axial direction, the radially inward end of the annular coverserves as an opening, at least two clearance sections serve as a reservoirfor reserving the magnetic fluid, and a magnetomotive force memberis provided for concentrating the magnetic flux lines on the radially outer side of the end portionof the magnetic fluid

Dynamic pressure bearing and rotation machine employing same

A ferrofluid sealing device retaining a ferrofluid between a shaft and a pair of inner and outer pole pieces rotating in opposite directions, in which grooves are formed on a shaft surface that faces the inner diameter surfaces of pole pieces. In the sealing device, one of the pole pieces may be made thicker than the other and further a projection portion can be formed on the shaft surface facing the inner peripheral faces of the pole pieces. The sealing device can prevent, even when the ferrofluid seal is operated at a higher rotation speed, splashing of ferrofluid over the surroundings, thereby avoiding staining the surroundings as well as prolonging its lifetime.

Ferrofluid sealing device

A sealing apparatus which is disposed between the media side and the bearing side and adapted to hermetically seal members rotating concentrically relative to each other, wherein a passageway having in a U-shaped cross section is formed by an outer shielding member on the media side, an outer shielding member on the bearing side and an inner shielding member, the end portion of which is inserted into the cavity between the outer shielding members. The end portion of the inner shielding member has a T-shape or L-shape. A magnet is arranged at either the inner shielding member or the outer shielding member. A ferrofluid is retained in the cavity by the surrounding magnet. An oil repellent material may be coated on the surface of the inner shielding member except for a portion extending into the cavity and an adhered portion on its inner diameter side.

Growing community of inventors

Chiba, Japan

Heiichi Unozawa