Air gap magnetic coupling with thermal isolation
AssigneeAgilent Technologies, Inc.
InventorRonald J. Forni
Life of this patent
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Abstract
A magnetic coupling assembly includes a thermal isolation system that isolates the assembly from a heat source such as a pump coupled to a driven side of the assembly, thereby enabling the assembly to operate at a reduced temperature. The system may include a labyrinth seal that reduces convective heat transfer to the assembly. The seal may include a sealing gap defined between a rotating component and a stationary component. The gap is sized to limit gas conductance therethrough. The system may also include one or more spacers positioned to reduce or eliminate conductive heat transfer from one component to another. The assembly may be utilized in a pump for contactless coupling of a motor shaft to a pump shaft.
Claims20
A magnetic coupling assembly, comprising:
- a drive shaft rotatable on a drive axis;
- a driven shaft rotatable on the drive axis;
- a drive magnet assembly coupled to the drive shaft and rotatable therewith;
- a driven magnet assembly coupled to the driven shaft and rotatable therewith, and spaced from the drive magnet assembly by an air gap;
- a first housing coupled to the driven shaft and rotatable therewith, the first housing comprising at least one first seal surface;
- a second housing disposed about the drive axis and surrounding the first housing, the second housing comprising at least one second seal surface, wherein the first housing and the second housing at least partially define a chamber disposed about the drive axis;
- and
- a labyrinth seal comprising a sealing gap formed between the at least one first seal surface and the at least one second seal surface and fluidly communicating with the chamber, wherein:
- the chamber is disposed axially between the sealing gap and the driven magnet assembly;
- and
- the sealing gap has a size effective to limit gas conductance therethrough and thereby thermally isolate the chamber from a region external to the sealing gap and the chamber.
A method for operating a magnetic coupling assembly, the method comprising:
- providing the magnetic coupling assembly with a drive magnet assembly and a driven magnet assembly spaced from each other by an air gap, wherein the drive magnet assembly and the driven magnet assembly are coupled by a magnetic field;
- providing a first housing coupled to the driven shaft and rotatable therewith, the first housing comprising at least one first seal surface;
- providing a second housing disposed about the drive axis and surrounding the first housing, the second housing comprising at least one second seal surface, wherein the first housing and the second housing at least partially define a chamber disposed about the drive axis:
- providing a labyrinth seal comprising a sealing gap formed between the at least one first seal surface and the at least one second seal surface and fluidly communicating with the chamber, wherein the chamber is disposed axially between the sealing gap and the driven magnet assembly;
- and
- rotating the drive magnet assembly about a drive axis to drive rotation of the driven magnet assembly about the drive axis via the magnetic field, and to drive rotation of the at least one first seal surface relative to the at least one second seal surface,
- wherein, during the rotating, the sealing gap has a size effective to limit gas conductance therethrough and thereby thermally isolate the chamber from a region external to the sealing gap and the chamber, and from which region heat energy propagates toward the sealing gap.
Dependencies are inferred from the claim text.