US 4,447,063 AGranted

Shaft seal with positively magnetically controlled sealing gap

AssigneeM.A.N. Maschinenfabrik Augsburg-Nurnberg Aktiengesellschaft

InventorsJoachim Kotzur, Hans H. Reinersmann, Rolf Albers, Emil Aschenbruck, Gunter Neuhaus

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Abstract

In a shaft seal having a radial plane seal ring gap and comprising a seal ring rotating with a shaft, and a non-rotating seal ring mounted on a housing of the seal through an element which is elastically yielding in every direction and serves as a packing at the same time, the sealing fluid flows into the sealing gap through supply bores and through associated distributing pockets which are provided in the non-rotating seal ring and/or at the outer or inner circumference of the rotating seal ring. Sensors for measuring the sealing gap are provided in the non-rotating seal ring on the gap side. By means of the measured values, electromagnets disposed in the seal housing to face each other and cooperating with opposite magnetizable bodies provided in the non-rotating seal ring, are electronically controlled to maintain a predetermined constant small width of the seal gap. The electromagnets are disposed axially at both sides of a shoulder portion of the non-rotating seal ring to be effective in opposite directions, against each other.

Claims12

Dependent claims

A seal device for a shaft rotating with respect to a housing, comprising:

a rotating seal ring connected to and co-rotating with the shaft;
a non-rotating seal ring non-rotatably associated with the housing and defining a radial plane sealing gap with said rotating seal ring;
a packing element which is elastically yieldable in all directions, connected between the housing and said non-rotating seal ring for permitting relative motion therebetween to vary a width of the gap and exert a resetting force on said non-rotating seal ring;
sealing fluid means for supplying a sealing fluid to said gap under a supply pressure for exerting a fluid force between said rotating and non-rotating seal rings, said sealing fluid means supplying sealing fluid over at least one supply bore communicating with said gap;
said non-rotating seal ring having a radially extending shoulder with magnetically attractable material connected thereto, the housing having an annular recess for receiving said shoulder;
an electromagnet connected to the housing on each axial side of said shoulder and adjacent said recess for exerting a magnetic force on said shoulder through said magnetically attractable material;
at least one sensor connected to said non-rotating seal ring for sensing a width of said gap;
and
control means connected to said at least one sensor and each said electromagnets for activating at least one of said electromagnets in response to said at least one sensor for applying a selected magnetic force to act in conjunction with said fluid force and aid resetting force to maintain a selected width for said gap.

6 more elements

Dependencies are inferred from the claim text.