Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Reexamination Certificate
1999-10-19
2001-11-27
Sandy, Robert J. (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
C277S384000, C277S586000
Reexamination Certificate
active
06322079
ABSTRACT:
FIELD OF INVENTION
This invention relates to an improved face seal and more particularly to such an improved face seal which can be combined with a rotor assembly to form a cartridge and to an assembly tool useful therewith.
BACKGROUND OF INVENTION
A common use of seals is to prevent fluids from leaking around shafts in aircraft gearboxes, aircraft accessories, pumps, motors, turbines, spindles, and other rotating equipment. Typically, mechanical face seals or lip seals are used to seal such shafts, but there are distinct disadvantages to both types of seals. Mechanical face seals operate at higher speeds and pressures and seal life is far superior to that of existing lip seals. However, mechanical face seals are normally three times axially longer than a lip seal for the same application and are thus unsuitable for use. The ideal seal would have the axial length of a lip seal with the performance of a mechanical face seal. Attempts at shortening existing mechanical face seals have not been successful due to seal face distortion as seal axial length is reduced. Distortion of the seal face causes seal leakage to increase excessively and thus the seal cannot be used.
Additionally, rotors on existing mechanical face seals normally are positioned against a step in the shaft or the end of a bearing to prevent axial movement of the rotor relative to the shaft. Existing rotors normally also have engagement into the shaft to ensure that the rotor rotates with the shaft. If a mechanical face seal is to be used to replace an existing lip seal, the rotor must be capable of being positioned on a shaft without a step and be capable of being rotated with the shaft without relative axial or radial movement. The rotor must also prevent leakage between the rotor and the shaft.
BRIEF SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide an improved seal assembly for a face seal.
It is a further object of this invention to provide such a seal assembly for a face seal which can operate at a reduced axial length and weight.
It is a further object of this invention to provide such a seal assembly for a face seal which can be used in the same space as a lip or magnetic seal.
It is a further object of this invention to provide such a seal assembly for a face seal with an improved seal between the sealing composite and a rotor.
It is a further object of this invention to provide such a seal assembly which positions a rotor on a shaft without a step.
It is a further object of this invention to provide such a seal assembly for a face seal which inhibits radial and axial movement of a rotor along a high velocity rotating shaft.
It is a further object of this invention to provide such a seal assembly for a face seal that the seal assembly, rotor and rotor drive ring can be assembled together as a cartridge.
It is a further object of this invention to provide such a seal assembly for a face seal that the seal assembly, rotor, and rotor drive ring can be configured separately.
It is a further object of this invention to provide an assembly tool for installing such a cartridge.
The invention results from the realization that a truly effective, smaller face seal can be achieved by using a support shell to support a primary seal insert and folding the housing so that the secondary seal is disposed proximate the seal insert resulting in an axially shorter length and the further realization that an improved rotor can be made which is both sealed to and inhibited from moving along a shaft to be sealed by providing a sealing ring groove which has a first section which is equal to or smaller than the sealing ring to hold and compress it and a second section which is larger than the sealing ring to allow it to maximize sealing ring compression to ensure maximum holding power of the sealing ring.
This invention features a seal cartridge for a face seal including an annular housing having an inner and outer wall and a back wall and a seal ring composite in the housing. A first resilient member is disposed between the housing and the seal ring composite for providing an axial bias on the seal ring composite. The seal ring composite includes a support shell and a sealing insert supported in the shell for providing a primary seal with a rotor. A second resilient member is disposed between the seal ring composite and one of the inner and outer walls for providing a secondary seal. The rotor is located in the housing, the rotor having a sealing ring groove between the rotor and a shaft to be engaged. The groove has an inner end and an outer end. A sealing ring is disposed in the groove, the groove having a width at its inner end approximately equal to or less than the width of the sealing ring and a width at its outer end confronting the shaft greater than the width of the sealing ring for sealing the rotor to the shaft and inhibiting axial movement of the rotor along the shaft.
In a preferred embodiment, the first resilient member may be a spring. Further, the first resilient member may be a wave washer. The first resilient member may be disposed between the back wall of the housing and the seal ring composite, and more specifically, between the back wall of the housing and the support shell. The second resilient member may be disposed between the inner wall of said housing and the seal ring composite, and more specifically, between the inner wall of the housing and the sealing insert. The second resilient member may be an “O” ring. The sealing insert may be made of carbon. The housing and the seal ring composite may be engaged to prevent rotation of the seal ring composite. The sealing ring groove may include at least two stepped sections. The sealing ring groove may have tapered side walls. The sealing ring may be an “O” ring. The seal cartridge may further include an assembly tool having a bearing surface for engaging the seal cartridge. The assembly tool may have a first bearing surface for engaging the rotor and a second bearing surface spaced from the first bearing surface for engaging the housing and preloading the first resilient member, maintaining engagement of the sealing insert with the rotor and setting the axial extent of the seal cartridge.
Another embodiment of this invention features a face seal cartridge assembly kit comprising an annular housing and a seal ring composite in the housing. A first resilient member is disposed between the housing and the seal ring composite for providing an axial bias on the seal ring composite. A second resilient member is disposed between the seal ring composite and the housing for providing a secondary seal. The rotor is located in the housing, the rotor having a sealing ring groove between the rotor and a shaft to be engaged. A sealing ring is disposed in the sealing ring groove. Also included is an assembly tool having a first bearing surface for engaging the rotor and a second bearing surface spaced from the first bearing surface for engaging the housing and preloading the first resilient member, maintaining engagement of the sealing insert with the rotor and setting the axial extent of the seal cartridge.
Another embodiment of this invention features a seal assembly for a face seal including an annular housing having an inner and outer wall and a back wall and a seal ring composite in the housing. A first resilient member is disposed between the housing and the seal ring composite for providing an axial bias on the seal ring composite. The seal ring composite includes a support shell and a sealing insert supported in the shell for providing a primary seal with a rotor. A second resilient member is disposed between the seal ring composite and one of the inner and outer walls for providing a secondary seal.
In a preferred embodiment, the first resilient member may be a spring. Further, the first resilient member may be a wave washer. The first resilient member may be disposed between the back wall of the housing and the seal ring composite, and more specifically, between the back wall of the housing and the support shell. The second resilient
Iandiorio & Teska
PerkinElmer Inc.
Sandy Robert J.
Schwing Karlena D.
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