Low and reverse pressure application hydrodynamic pressurizing seals

Abstract

The present invention relates to circumferential seal ring segments positioned around a rotating shaft so as to prevent fluids from leaking from a lubricant sump during both low and high pressure conditions. The circumferential seal is comprised of a plurality of adjoining annular ring segments facing the rotating shaft. Each sealing ring segment includes a dead end circumferential groove on a shaft-side face of each sealing ring such that, when the segments are joined, the circumferential dead end groove of each segment extends arcuately in the direction of shaft rotation. At least one additional groove is contained on the shaft-side face of each sealing ring segment. The additional groove(s) directs and creates pressurized air within the dead end circumferential groove, either directly or indirectly maintaining a seal between the ring segments and the shaft. A bleed hole may also be provided to create a seal between each sealing segment.

Description

CROSS REFERENCE TO RELATED PATENT APPLICATION[0001]This patent application is a continuation-in-part of U.S. patent application Ser. No. 11 / 821,578, filed on Jun. 21, 2007, which claims priority from Provisional U.S. Patent Application Ser. No. 60 / 815,782, filed Jun. 21, 2006, in the names of Thurai Maanik Vasagar, Alan D. MeNieckle (now deceased), and Glenn Marke Garrison, and assigned to Stein Seal Company.FIELD OF THE INVENTION[0002]The present invention relates to an apparatus and method for sealing a liquid sump. More specifically, the present invention relates to seal ring segments designed to generate high gas pressures across the seal and around a rotating shaft so as to prevent liquids from leaking from a liquid side of the seal to a gas side of the seal during low and high pressure conditions.BACKGROUND OF THE INVENTION[0003]There are many applications wherein housings are provided with a plurality of interior sections having rotating parts passing therethrough, wherein on...

AI Technical Summary

Benefits of technology

[0008]The present invention relates to an apparatus and method for sealing a liquid sump. More specifically, the present invention relates to circumferential seal ring segments designed to generate high gas pressures across the seal face and around a rotating shaft so as to prevent liquid from leaking from a lubricant side to a gas side of the seal during both low and high pressure conditions.

[0010]The seal cavity formed between the shaft and fluid seal housing is sized to receive the circumferential seal of the present invention, which is comprised of a plurality of segmented rings mechanically urged inwardly toward the shaft. The seal may also be biased against a seal cavity wall by a plurality of springs and support rings. By urging the seal against both the shaft and the seal cavity wall. the seal and, ultimately, the fluid seal assembly isolate the sump housing chamber such that lubricant may be prevented from passing through the open end of the housing sump, i.e. from the lubricant side to the gas side, when the shaft is not rotating.

[0014]In operation, when the shaft rotates, the inclined grooves direct fluid, preferably air, generated by the rotation of the shaft along the inclined grooves and into the dead end groove. As the air passes along the inclined grooves, it begins to accumulate within the dead end circumferential groove, thus increasing the pressure therein. This pressure is redirected toward the shaft creating a lift force on the seal segments wherein the lift force expands the sealing segments away from the shaft creating a minute clearance between the shaft-face of the seal segments and the rotating shaft. The redirection of the pressurized air within the dead end groove toward the shaft also creates an air / pressure seal within this minute clearance wherein the force of the high-pressure gas is at a sufficient velocity to prevent lubricant stored within the chamber from passing through the clearance. This air pressure seal is juxtaposed to the bore dam of the shaft-face of the seal such that the bore dam acts in concert with the air / seal to prevent lubricant from escaping from the housing chamber during operation of the turbine engine. In other words, lubricant is prevented from escaping from the lubricant side to the gas side of the chamber. This configuration has the advantages of creating an air seal that does not interfere with the rotation of the shaft, while reducing the wear on the shaft-side face seal as a result of the rotation of the shaft.

[0015]Pressurized gas from the dead end circumferential groove may also be released into the tongue / socket joints by way of a gas bleed hole. By allowing pressurized air from the dead end groove to leak into the sockets, the pressurized air also acts as an seal within the socket / tongue joints of two adjacent seal segments and flows at a high velocity so as to prevent lubricant from the liquid side from passing through the joints of the seal segments. To this end, this prevents liquid weepage through the tongue / socket joints.

Problems solved by technology

Leakage of liquids from the lubricant side into the gas side adversely affects performance of the equipment where the seal is used.

In case of an aircraft engine, oil leakage across the seal into a hot air side may cause oil coking or an engine fire.

More specifically, when an oil lubricant is used, mixing the oil with the gas could result in formation of oil coke, a byproduct of oil heated to an elevated temperature, which chemically alters the oil and is detrimental to the gas turbine.

Oil coke can foul seal surfaces reducing the integrity of the seal and prevent proper bearing lubrication within the lubricant sump.

Liquid leaking, as noted above, increases the risk of oil coking and fouling the seal face.

This increases the risk of engine fire and increases the risk of oil odor within a vehicle housing the engine.

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