Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Reexamination Certificate
1998-11-05
2001-04-17
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
C277S385000, C277S390000
Reexamination Certificate
active
06217028
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a seal assembly for providing sealing engagement between a vessel and a rotatable shaft extending through a wall of the vessel.
2. Description of Prior Art
In material processing equipment it is common that a rotatable shaft is positioned through a wall of a vessel containing material. The interface between the rotatable shaft and the vessel is often the source of leaks of the material as the rotatable shaft rotates. Mechanical, safety and efficiency problems may occur if the material contaminates the processing equipment, the material is hazardous or the material is expensive.
Stuffing boxes were often used in the prior art in an attempt to seal the area between the rotatable shaft and the vessel. A stuffing box comprises a box that is filled with dense packing or stuffing attached to the vessel around the interface between the vessel and the rotatable shaft. Such stuffing boxes are often ineffective after extended periods because the packing or stuffing begins to wear away around the rotatable shaft.
Other prior art sealing apparatuses, such as Escue, U.S. Pat. No. 4,575,098, use a series of rotatable components attached with respect to the shaft and the vessel. The Escue patent teaches an undersized collar attached to the shaft which rotates around an insert and a faceplate. The seal apparatus taught by the Escue patent involves many rotating components which may result in wear of several different components. Such wear results in frequent replacement of various components.
SUMMARY OF THE INVENTION
It is one object of this invention to provide a seal apparatus that eliminates leakage between a vessel and a rotatable shaft extending through a wall of the vessel.
It is another object of this invention to provide a seal apparatus that does not require frequent replacement of sealing members.
It is still another object of this invention to provide a seal apparatus that does not lose its seal when the rotatable shaft expands or contracts.
It is yet another object of this invention to provide a seal apparatus that occupies less space than prior art seal apparatuses.
It is another object of this invention to provide a seal apparatus having a minimum of rotating components.
It is yet another object of this invention to provide a seal apparatus wherein replacement components are easy to replace.
A seal apparatus according to this invention for providing sealing engagement between a vessel and a rotatable shaft extending through a wall of the vessel achieves the above objects and is described in more detail below.
The seal apparatus includes an insert retainer mounted to the vessel. The insert retainer preferably includes an inner diameter formed around the rotatable shaft. The inner diameter of the insert retainer is preferably substantially larger than an outer diameter of the rotatable shaft.
A shaft ring, having an inner diameter approximately equal to an outer diameter of the rotatable shaft, is mounted to the rotatable shaft and rotatably positioned within the insert retainer. The shaft ring is preferably the only rotating component in the entire seal apparatus.
An insert, having an inner face and an outer face, is positioned against the shaft ring and within the insert retainer. The insert is constructed of Teflon® or similar material and is preferably the only component in the seal apparatus requiring occasional planned replacement. The insert preferably fits snugly within the insert retainer and includes a sealing member, such as an O-ring cord, positioned between the insert and the insert retainer.
A retainer assembly biases the insert against the shaft ring to complete the seal apparatus. The retainer assembly preferably includes a bias plate positioned against the insert and a retainer plate positioned opposite the insert and adjacent the bias plate. The retainer plate is preferably connected with respect to the insert retainer and includes bias members for biasing the bias plate against the insert.
As a result of the seal assembly described herein, the vessel does not leak material through the interface between the rotatable shaft and the vessel. The seal assembly includes only one rotating component, the shaft ring, and only one component that must occasionally be replaced, the insert.
REFERENCES:
patent: 3072414 (1963-01-01), Porges
patent: 4215870 (1980-08-01), Escue
patent: 4219202 (1980-08-01), Koch
patent: 4423878 (1984-01-01), Escue
patent: 4575098 (1986-03-01), Escue
patent: 4583748 (1986-04-01), Weichenrieder, Sr.
patent: 4625977 (1986-12-01), Azibert et al.
patent: 4906008 (1990-03-01), Warner
patent: 5403020 (1995-04-01), McOnie
patent: 5538257 (1996-07-01), Sandgren
patent: 5571268 (1996-11-01), Azibert
patent: 5716054 (1998-02-01), Duffee et al.
patent: 6120034 (2000-09-01), Kowalski et al.
Custom Shaft Seals, MECO Systems brochure, Woodex Bearing Company, Inc., Bay Point Road, Box 37-A, Georgetown, Maine 04548. No date.
Carl Sorrell and William P. Stadig: Flexible mechanical seal stops loss of 800 lb/day of fine, abrasive powder,Chemical Processing, Mar. 1988.
William P. Stadig, David L. Gatling and Andrew J. Morey: Mechanical seal tolerates eccentric rotation,Chemical Processing, Aug. 1991.
Beres John L.
Knight Anthony
Pauley Petersen Kinne & Fejer
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