Seal for a joint or juncture – Seal between relatively movable parts – Close proximity seal
Reexamination Certificate
1998-07-09
2001-08-14
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Close proximity seal
C277S419000, C277S585000
Reexamination Certificate
active
06273429
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to cartridge seals. More particularly, the present invention relates to labyrinth cartridge seals having a shell and a plurality of sleeves which are correspondingly shaped to prevent radial and axial movement therebetween.
BACKGROUND OF THE INVENTION
In an integrally geared centrifugal compressor, pressurized gas tends to leak axially along the rotating shaft of the compressor and into the driving mechanism such as an oil lubricated gear box. Cartridge seals provide safe operation of the compressor by properly sealing, venting, or buffering the pressurized gas from the oil lubricated gear box. In compressors for compressing gas such as oxygen, oil used for lubricating the gear box must be isolated from the oxygen to prevent fires.
FIG. 1
illustrates a prior art cartridge seal
10
which comprises a bronze shell
12
having a single, elongated, silver sleeve
14
disposed therein. Sleeve
14
is provided with a plurality of ports extending through both shell
12
and sleeve
14
and opening onto the inner surface of sleeve
14
for venting or providing a buffering gas between sleeve
14
and a shaft of a compressor (not shown). During manufacture, a semi-finished silver sleeve
14
is installed into a semi-finished shell
12
and the various ports are drilled through shell
12
and sleeve
14
while assembled together to ensure proper alignment. The inner bore is finished to its required diameter ensuring proper concentricity with the outer diameter of the cartridge. The cartridge seal is then disassembled, deburred, and cleaned prior to final installation into a compressor.
The illustrated prior art cartridge seal
10
while suitable for its intended purpose includes a number of drawbacks. The fabrication of cartridge seal
10
is labor and time intensive due to the required drilling and deburring of the ports. In addition, increasing the number of ports to increase the flow areas between the shaft of the compressor and sleeve for venting or providing a buffering gas reduces the strength of the sleeve and/or shell.
U.S. Pat. No. 4,343,591 to Hannan, III et al. discloses a turbomachine seal system having first and second seal members spaced axially about the shaft of the turbomachine to define therebetween a first annular chamber. Shims are required for positioning the seals axially and radially about the shaft.
U.S. Pat. No. 4,500,096 to Tuttle et al. discloses a turbine shaft seal assembly having three split seals with axial portions or dowel pins which abut each other or which require spacer rings to axially position the seals relative to each other. A gland exhaust opening is provided in the turbine case between the first and second split rings, and a gland exhaust opening is provided in the turbine case between the second split seal and the third split seal.
A drawback of the above disclosed seal assemblies having multiple seals is that they require separately configured elements for positioning the seals axially and/or radially about the shaft of the turbine. In addition, the seal elements are typically fabricated entirely from materials best suited to the gases, e.g., expensive metals or metal alloys. Furthermore, the seal elements typically require excess material in order to properly position the seal which also increases the overall cost.
Therefore, there is a need for labyrinth cartridge seals comprising a shell and a plurality of sleeves using a minimum amount of sealing material and having corresponding portions to prevent axial and radial movement therebetween, which reduce the labor, time, material, and/or cost required for fabrication, and which provide increased areas for venting or receiving a buffering gas to isolate a gas being compressed from the drive mechanism of the compressor.
SUMMARY OF THE INVENTION
Pursuant to the present invention, the shortcomings of the prior art are overcome and additional advantages provided by a labyrinth cartridge seal having a shell and a plurality of sleeves having corresponding portions to prevent axial and radial movement therebetween. The sleeves can be fabricated from various materials suitable to sealing a variety of gases while minimizing the amount of material used. Such a labyrinth cartridge seal is particularly suitable for use in an oxygen compressor which requires costly seal materials in order to restrict the leakage of the pressurized oxygen to a drive mechanism, such as an oil lubricated gear box, to thereby reduce the likelihood of fires.
In one embodiment of the present invention, a labyrinth cartridge seal includes a shell having a passageway through the shell and a least one port opening onto said passageway, and at least two sleeves each of which has an inner surface along which a shaft of a compressor can be positioned. Each of the sleeves and the shell have corresponding portions which complementarily engage each other to radially, and axially support the sleeves in fixed, spaced-apart positions along the passageway to define a chamber around the shaft with the port opening into said chamber. Increased flow areas between the sleeves can be made by cutting annular grooves in the shell to increase the size of chambers
42
,
44
, and
46
.
The shell may include at least two, spaced-apart, inwardly extending annular portions which define a portion of the passageway. The sleeves may each include at least two outwardly extending spaced-apart, annular-shaped portions between which one of the inwardly extending annular-shaped portions of the shell is received. Desirably, the shell comprises a first half and a releasably attachable second half, and the sleeves comprise unitary sleeves.
In another embodiment of the present invention, a labyrinth cartridge seal includes a shell comprising a passageway therethrough, and four spaced-apart, concentrically aligned sleeves, axially and radially supportable along the passageway and generally sealable with the shell to define three separate chambers around the shaft. The shell has three ports, each one opening into a different one of the three separate chambers.
Another embodiment of the present invention relates to a compressor for pressurizing a gas, in which the compressor comprises a shaft, a drive mechanism attached to a first end portion of the shaft for rotating the shaft, an impeller attached to a second end portion of the shaft for pressurizing the gas, and a casing for supporting the shaft and the drive mechanism. A labyrinth cartridge seal as described above is disposed between the shaft and the casing for restricting the flow of pressurized gas along the shaft toward the drive mechanism.
One of the ports may be operably connected to return pressurized gas to the inlet of the impeller, one of the ports may be operably connected to vent the chamber to the atmosphere, and one of the ports may be operably connected to receive a buffering gas.
REFERENCES:
patent: 2356011 (1944-08-01), Sheldon
patent: 3053541 (1962-09-01), Dega
patent: 3503616 (1970-03-01), Hickey
patent: 4017127 (1977-04-01), Smith et al.
patent: 4139204 (1979-02-01), Howe
patent: 4314705 (1982-02-01), Shimizu
patent: 4343591 (1982-08-01), Hannan, III et al.
patent: 4396197 (1983-08-01), Shimizu
patent: 4486024 (1984-12-01), Cooper
patent: 4500096 (1985-02-01), Tuttle et al.
patent: 4627795 (1986-12-01), Schmitz-Montz
patent: 4721313 (1988-01-01), Pennink
patent: 4961260 (1990-10-01), Ferri et al.
patent: 4993917 (1991-02-01), Kulle et al.
patent: 5087172 (1992-02-01), Ferri et al.
patent: 5215047 (1993-06-01), Neutgens
patent: 5348456 (1994-09-01), Kun et al.
patent: 5382141 (1995-01-01), Stinessen
patent: 5503523 (1996-04-01), Prumper
patent: 5662171 (1997-09-01), Brugman et al.
patent: 5913812 (1999-06-01), Smith et al.
Dudinetz Michael J.
Hubert Ralph F.
Streifert Kenneth W.
Atlas Copco Aktiebolag
Heslin & Rothenberg, P.C.
Knight Anthony
Pickard Alison K.
LandOfFree
Labyrinth cartridge seal, and centrifugal compressor... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Labyrinth cartridge seal, and centrifugal compressor..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Labyrinth cartridge seal, and centrifugal compressor... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2437230