Rotary face seal with magnetic puller loading
The rotary face seal with magnet loading replaces known spring mechanisms with magnetic technology that provides a consistent load with minimal variation, which is not affected by natural frequency and material fatigue due to cyclic loading. This improves seal performance and service life. The tubular magnetic ring is advantageous because it replaces existing seals within stationary cartridge with a puller type magnetic assembly design that results with the stationary cartridges being an exact exchange. The use of magnetic technology attached to the outside diameter of the rotating mating ring, which is attached to the shaft, that does not produce eddy currents because it is of a single pole configuration. The single pole magnetic assembly design is achieved by either axial or radial magnet orientation, such as in the form of a tubular magnetic band locating in a circumferential notch in the rotating mating ring.
1. A rotary face seal with magnetic loading which sealingly couples a shaft to a stationary housing, comprising:
the stationary housing having a seat;
a cup having an inwardly facing groove and a central bore, the cup being disposed in the stationary housing; and the shaft located in the central bore;
a seal case residing between the cup and the shaft;
an O-ring residing in the inwardly facing groove of the cup to sealingly interface the cup with the seal case providing a secondary seal and allowing axial movement of the seal case within and relative to the cup;
a retaining ring connecting the cup to the seal case thereby preventing the seal case from becoming disengaged from the cup;
a seal ring at least partially axially aligned with and in communication with the seal case;
a rotating mating ring, having a seal face in communication with the seal ring; the rotating mating ring rotating with the shaft;
a magnetized band connected to the rotating mating ring; the magnetized band and the seal case being magnetically attracted to and pulled toward each other thereby providing a mechanical puller load assembly in the rotating mating ring thereby urging the seal case toward the rotating mating ring and the seal ring into sealing communication with the seal face of the rotating mating ring,
wherein the magnetized band is axially oriented and magnetized with a single pole adjacent to the seal case, and
wherein the seal ring maintains an air gap, in an axial direction, between the seal case and the magnetized band.
2. The rotary face seal of claim 1 , further comprising:
wherein complementary structures on the seal case and in the cup to prevent rotation of the seal case relative to the cup when the seal ring contacts a rotating mating face.
3. The rotary face seal of claim 1 , wherein the magnetized band resides in a circumferential notch in the rotating mating ring.
4. The rotary face seal of claim 1 , wherein the rotary face seal is configured and arranged as a self-contained cartridge.
5. The rotary face seal of claim 1 , wherein the rotating mating ring further includes a groove with an O-ring residing therein with the O-ring in communication with the shaft to secure the rotating mating ring to the shaft to effectuate rotation of the rotating mating ring with the shaft.
6. The rotary face seal of claim 1 , wherein the seal face of the rotating mating ring further includes a plurality of hydrodynamic grooves.
7. The rotary face seal of claim 1 , wherein the magnetized band is an annular ring.
8. The rotary face seal of claim 1 , wherein the magnetized band does not produce eddy currents.