Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Reexamination Certificate
1998-09-30
2001-02-13
DePumpo, Daniel G. (Department: 3611)
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
C277S372000, C277S375000, C277S379000
Reexamination Certificate
active
06186510
ABSTRACT:
TECHNICAL FIELD
This invention relates to mechanical face-type shaft seal assemblies.
BACKGROUND
Pumps, motors and other devices which employ a shaft rotatable within or on a bearing often require resilient seals between the shaft and the bearing housing through which the shaft extends. Besides a portion of the rotatable shaft and the bearing itself, the bearing housing contains lubricant to reduce friction within the bearings. Operating conditions may require that the seal between the shaft and the bearing housing inhibit water, air, dirt particles or other foreign objects from contaminating or otherwise deteriorating the lubricant content of the bearing housing. In mechanical seals, the seal between the shaft and the bearing housing usually is provided by two resilient sealing faces in rotatable and sealing relation with one another, one face being stationary relative to the shaft, and the other being in rotational engagement with the shaft.
Given the rotational relationship between the stationary face and the rotary face, a biasing force is usually required to maintain the seal. Various configurations providing for, among other things, biasing force within a mechanical face-type seal assembly are known in the art. For example, U.S. Pat. No. 4,906,008 to Warner describes a seal assembly employing a wave spring, while use of leaf springs and compression springs have also been described, for example, in U.S. Pat. No. 3,799,559 to Kayser and in U.S. Pat. No. 2,844,393 to Jansen, respectively. The use of interconnected canted coils in lip seals has been described in U.S. Pat. No. 4,655,462 to Balsells.
Notwithstanding developments in the prior art, a need continues to exist for a mechanical face-type seal assembly which provides an improved substantially annular biasing force to the sealing faces of a mechanical face-type seal assembly. Prior art configurations provided biasing force at only selected points along the annular surface of the seal faces, often times resulting in uneven wear and increasing the likelihood of leakage at the junction of the sealing faces. As will be further discussed below, so far as is known, cartridge-type configurations have heretofore been unknown in seal assemblies used in bearing housing shaft apertures, especially when relatively thin and/or relatively short assemblies are required. Accordingly, a need also exists for a mechanical face-type seal which has a cartridge-type configuration. Additionally, a need persists for a mechanical face-type seal assembly which can be relatively thin (about 0.15 to about 0.25 inch) in cross-section width, i.e., in a direction transverse to the axis of the shaft, and/or relatively short (about 0.625 to about 0.875 inch) in cross-section length, i.e., in a direction parallel to said axis, and yet has a cartridge-type configuration. As used herein, the term “cartridge” or “cartridge-type configuration” means a configuration of multiple and separate parts which may be installed as a single, preassembled unit.
SUMMARY OF THE INVENTION
In one of its embodiments, this invention provides an improved mechanical face-type seal assembly which fulfills the need for a substantially annular, axially biasing force along the annular seal created between the rotary seal face and the stationary seal face in a mechanical seal. Preferably, the device combines the substantially annular, axial biasing force of biasing means in the form of annularly disposed interconnected canted coils with a mechanical seal assembly employing a rotary seal face and a stationary seal face. The device of this invention also provides a cartridge-type configuration for maintaining the sealing rings and the interconnected canted coils in axial alignment with one another, and for easily installing the entire seal assembly as a single cartridge on a variety of applications.
More particularly, this invention provides, inter alia, a mechanical face-type seal assembly for sealing space between a bearing housing wall and a rotatable shaft which extends through an aperture in the housing wall, comprising (a) a stationary seal ring having a radially extending axially facing stationary seal face; (b) a rotary seal ring rotatable relative to the stationary seal ring and having a radially extending axially facing rotary seal face; (c) biasing means (preferably in the form of a substantially annular segment of interconnected canted coils); and (d) a seal housing substantially encasing the seal rings and sized and configured to be placed around the shaft and nonrotatably inserted into the aperture, thereby creating a seal between the seal housing and the bearing housing wall, the biasing means also being disposed within the seal housing to produce a biasing force to urge and maintain the seal faces in sealing contact with each other.
Another embodiment of this invention further includes first elastomeric means annularly disposed within an inner O-ring groove in the inner diameter of the rotary seal ring for maintaining a seal between the rotary seal ring and the rotatable shaft, and second elastomeric means annularly disposed within an outer O-ring groove in the perimeter of the stationary seal ring and within the seal housing for maintaining a seal between the stationary seal ring and the seal housing.
In a Preferred Embodiment, the Seal Housing Further Comprises
(a) an inner stationary housing ring including (i) an axially extending first annular wall having a free end and a connecting end, (ii) a radially extending second annular wall which is connected at one end to the connecting end of and substantially perpendicular to the first annular wall, thereby creating inner and outer surfaces of the inner stationary housing ring, (iii) first annular race means proximate to the free end for rotatably interlocking the inner stationary housing ring with an outer rotary housing ring described below, (iv) retaining means at the second annular wall for retaining the segment of interconnected canted coils in annular alignment with the seal rings; and (v) an annular outer surface recess within the portion of the outer surface formed by the first annular wall proximate to the connection between the first and second walls to facilitate insertion of the assembly into the aperture; and
(b) an outer rotary housing ring including (i) attachment means for detachably attaching the outer rotary housing ring to the rotatable shaft, (ii) a radially extending axially facing connecting face having engaging means for engaging the rotary seal ring in unified rotational relationship with the outer rotary housing ring, and (iii) a first axially extending radially facing outer face having second annular race means for cooperating with the first race means and rotatably interlocking the housing rings.
In Another Preferred Embodiment, the Seal Housing Further Comprises
a) an inner stationary housing ring including (i) an axially extending first annular wall having a free end and a connecting end, the free end being beveled at its most axial edge, and having proximate to the free end one or more evenly and annularly displaced apertures therethrough, (ii) a radially extending second annular wall which is connected at one end to the connecting end of and substantially perpendicular to the first annular wall, thereby creating inner and outer surfaces of the inner stationary housing ring, and (iii) retaining means at the second annular wall for retaining the segment of interconnected canted coils in annular alignment with the seal rings; and (iv) an annular outer surface recess within the portion of the outer surface formed by the first annular wall proximate to the connection between the first and second walls to facilitate insertion of the assembly into the aperture; and
b) an outer rotary housing ring including (i) attachment means for detachably attaching the outer rotary housing ring to the rotatable shaft and, when not installed, for attaching the free end to the outer rotary housing ring, (ii) a radially extending axially facing connecting face having engaging means for engaging the rotary sea
DePumpo Daniel G.
Power Packing Company, Inc.
Sieberth & Patty L.L.C.
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