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US 5,292,137 AGranted
Rotary shaft sealing method and device
AssigneeRotoflex, Inc.
InventorsBrian Simmons, Leonid G. Zeltser, Arnold Kholodenko
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AssigneeRotoflex, Inc.
InventorsBrian Simmons, Leonid G. Zeltser, Arnold Kholodenko
Estimating the term…
A dry-face sealing method for preventing leakage around a rotary shaft uses an annular rigid seal having a smooth sealing surface and an annular resilient seal having a projecting sealing edge aligned coaxially therewith. The annular resilient seal has a breaking elongation of at least about 100 percent of its original length, the resilient seal being stretched at least about 20 percent and less than 40 percent of its breaking elongation in a direction substantially parallel to the smooth sealing surface to align polymeric resilient seal components in a direction parallel with the smooth sealing surface and smooth the sealing surface thereof. The projecting edge, because of its shape and position, functions as a stress concentrator, concentrating the stress hardening effect on the sealing surface of the projecting edge. The method comprises pressing the projecting edge in an axial direction against the smooth sealing surface with a pressure which is sufficient to effect a seal therebetween under operating conditions of the seal but which will not produce sufficient heat of friction to cause significant chemical changes in the projecting edge of the resilient seal. The result is an effective rotary sealing which does not require a liquid for lubrication or radial emission suppression. The smooth sealing surface of the device can be adjusted to change the sealing pressure to accommodate operating conditions, using a moveable, threaded housing made of a material having a high thermal conductivity. This primary seal can be used alone or in combination with a backup dry face stuffing box seal.
A method for preventing leakage around a rotary shaft extending through a structural casing by contacting a rigid smooth sealing surface with a projecting sealing edge of an annular resilient seal without liquid lubrication therebetween, the resilient seal having a breaking elongation of at least about 100 percent of its original length, the resilient seal being stretched from at least about 20 up to about 40 percent of its breaking elongation in a direction substantially parallel to the smooth sealing surface, whereby to reduce the coefficient of friction between the projecting sealing edge and the smooth sealing surface by stress hardening the projecting edge, aligning polymeric resilient seal components in a direction parallel with the smooth sealing surface, and smoothing the sealing surface thereof;
A dry face rotary seal for preventing leakage around a rotary shaft comprising an annular rigid seal having a smooth sealing surface and an annular resilient seal having an annular projecting edge means for contacting the smooth sealing surface under a biased pressure to form a dry face seal in conjunction therewith, one of the rigid seal and the resilient seal being adapted for attachment to a rotary shaft and the other of the rigid seal and the resilient seal being adapted to be secured to a structural casing surrounding the rotary shaft, the resilient seal having a breaking elongation of at least about 100 percent of its original length, the resilient seal being stretched at least about 20 percent up to about 40 percent of its breaking elongation in a direction substantially parallel to the smooth sealing surface whereby the coefficient of friction between the projecting edge and the smooth sealing surface is reduced.
A combination of a dry rotary face seal and a dry stuffing box rotary seal for preventing leakage around a rotary shaft, the dry face rotary seal comprising an annular rigid seal having a smooth sealing surface means for establishing a dry face seal and an annular resilient seal having an annular projecting edge means for contacting the smooth sealing surface under a biased pressure to form a dry face seal in conjunction therewith, one of the rigid seal and the resilient seal being adapted for attachment to a rotary shaft and the other of the rigid seal and the resilient seal being adapted to be secured to a structural casing surrounding the rotary shaft, the resilient seal having a breaking elongation of at least about 100 percent of its original length, the resilient seal being stretched at least about 20 percent up to about 40 percent of its breaking elongation in a direction substantially parallel to the smooth sealing surface whereby the coefficient of friction between the projecting edge and the smooth sealing surface is reduced, and the dry stuffing box rotary seal comprising a gland packing receptor adapted to surround a rotary sealing surface axially concentric therewith, the packing receptor having a distal end and a proximal end, the distal end having a packing abutment surface, a sloped surface extending radially outward from the abutment surface toward the proximal end, an annular, plastic sacrificial packing positioned in the distal end, the sacrificial packing having a proximal surface, and an annular, slightly deformable primary packing positioned between the proximal surface of the sacrificial packing and the proximal end of the gland packing receptor.
Dependencies are inferred from the claim text.