Magnetic control closure system

• US 4,141,547 A
• Filed: 07/13/1977
• Issued: 02/27/1979
• Est. Priority Date: 07/20/1976
• Status: Expired due to Term

• Current Assignee: Societe Nationale dEtude et de Construction de Moteurs dAviation SNECMA (Safran SA)
• Original Assignee: Societe Nationale dEtude et de Construction de Moteurs dAviation SNECMA (Safran SA)
• Inventors: Plotkowiak, Joseph, Duquenne, Claude E. D.
• Primary Examiner(s): Smith, Robert I.
• Application Number:
  US05/815,281
• Time in Patent Office: 594 Days
• Field of Search: 277/80
• US Class Current: 277/629
• CPC Class Codes: F04D 29/143 especially adapted for elastic fluid pumps
• CPC Class Codes: F16J 15/008 with provision to put out of action at least one sealing; One sealing sealing only on standstill; Emergency or servicing sealings F16J15/164 takes precedence
• CPC Class Codes: F16J 15/54 Other sealings for rotating shafts
• CPC Class Codes: H01F 7/04 Means for releasing the attractive force
• CPC Class Codes: H01F 7/122 by permanent magnets H01F7/1615, H01F7/1646 take precedence
• CPC Class Codes: H01F 7/1646 Armatures or stationary parts of magnetic circuit having permanent magnet
• CPC Class Codes: H02K 5/124 Sealing of shafts
• CPC Class Codes: Y10S 277/919 Seal including electrical feature

Abstract

An annular seal is clamped in the active position of closure between statary knife-edges on the rotor of a rotating machine and movable knife-edges of a support member which can be displaced between an active position of magnetic coupling with the rotor and an inactive position of withdrawal from the rotor. The magnetic means have a second stable state of attraction in which the movable support member remains separated from the rotor in the inactive position.

Claims

1. A closure system for the rotor of a rotating machine for conveying a toxic fluid comprising an annular seal in a plane at right angles to the axis of rotation of the machine, said seal being clamped in an active position between stationary knife-edges on the rotor and movable knife-edges carried by an annular support member moving along the axis of the machine, the movable support member being displaced by magnetic means between an inactive position in which said member is separated from the rotor and the active position in which said member is coupled to the rotor as a result of magnetic forces of attraction, and the magnetic means having a second stable state of attraction in which the movable support member is maintained at a distance from the rotor in the inactive position and wherein the magnetic means exhibit symmetry of revolution and have two windings, one winding having two coils in series on each side of two annular permanent magnets, the other winding being a coil between the two permanent magnets for demagnetization and reversal of the residual magnetism of one of the permanent magnets.

2. A closure system according to claim 1, wherein the magnetic means cooperate in the inactive position with a pole-piece rigidly fixed to a frame of the machine.

3. A closure system according to claim 2, wherein the magnetic means includes a non-magnetic barrier to the magnetic flux on the side corresponding to attraction in the direction of the frame.

4. A closure system according to claim 3, wherein the barrier to the magnetic flux is a cylindrical groove in the armature.

5. A closure system according to claim 3, wherein the barrier to the magnetic flux is two frusto-conical annular grooves in the armature, one groove being on the same side as the pole-piece and the other groove being on the same side as the reversing coil.

6. A closure system according to claim 3, wherein the barrier to the magnetic flux is a ring of non-magnetic material in the armature.