Patent Application
20130287551
The field of the invention relates generally to gas turbines, and more particularly to methods and a system for a seal assembly for an inter-shaft seal in a gas turbine engine.
Labyrinth seals are widely used on rotatable shafts to regulate secondary air flows and provide a radial clearance between low speed shafts and high speed shafts in gas turbine engines. Generally, in more detail, the seals include a series of parallel teeth that facilitate regulating a flow past the teeth and capturing any excess oil. The tips of the teeth provide the clearance between the two shafts. Newer generation engines include shafts made of strong, but brittle materials that may not be as tolerant of the rubbing that typical seal teeth endure during engine operation. The rubbing can cause localized micro-cracking in the shaft. Seals made of a single unit that are integral to the shaft may not be allowable in some situations due to material or stress concerns. Additionally, sections of greater shaft diameter located both forward and aft of the seal can prevent implementation of the seal on an unbroken ring of material. Accordingly, a seal that is separable and not subject to the torque load of the shaft, which results in greater flexibility in design at a lower cost for repair and maintenance is desirable.
In one aspect, a seal assembly for sealing a rotatable shaft in a gas turbine engine, wherein the shaft includes sections of greater shaft diameter located both forward and aft of the seal shaft coupling point is provided. The seal assembly includes a first semi-annular segment with a first end, a second end, and a plurality of seal teeth, where the first and second ends each include an overlap joint. The seal assembly also includes a second semi-annular segment with a first end, a second end, and a plurality of seal teeth, where the first and second ends each include an overlap joint. The first end of the second segment is coupled to the first end of the first segment, and the second end of the second segment is coupled to the second end of the first segment.
The following detailed description illustrates an inter-shaft seal and a method of assembling the same by way of example and not by way of limitation. The description enables one of ordinary skill in the art to make and use the disclosure, and the description describes several embodiments of the disclosure, including what is presently believed to be the best mode of carrying out the disclosure. The disclosure is described herein as being applied to a preferred embodiment, namely, an inter-shaft seal and a method of assembling the same. However, it is contemplated that this disclosure has general application to shaft seals in a broad range of systems and in a variety of industrial and/or consumer applications.
In operation, air is drawn into engine inlet 26, and compressed through booster compressor 18 and high pressure compressor 20. The compressed air is channeled to combustor 22 where it is mixed with fuel and ignited to produce air flow through high pressure turbine 24 and low pressure turbine 16, and exits through exhaust 28.
Assembly of first and second segments 300 and 302 about shaft 30 is accomplished by heating both first and second segments 300 and 302 to a predetermined temperature, sliding first segment 300 in from a side of shaft 30, and sliding second segment 302 axially such that connectors 308 and 310 engage the mating halves of connectors 304 and 306, respectively. When allowed to equalize in temperature with shaft 30, an interference fit is generated between first and second segments 300 and 302 and shaft 30. First and second segments 300 and 302 enable the ring formed by their coupling to carry hoop stress. To hold first and second segments 300 and 302 together, a retaining ring 404 is expanded into a slot 406. Moreover, with reference to
Assembly of first and second segments 600 and 602 about shaft 30 is accomplished by heating both first and second inner ring segments 600 and 602, sliding first inner ring segment 600 in from the side, and sliding second inner ring segment 602 axially such that connector 610 engages the mating half of connector 612, and another set of connectors (not shown) engage on the other side of seal 34. When allowed to equalize in temperature with shaft 30, an interference fit is generated between first and second inner ring segments 600 and 602 and shaft 30, enabling segments 600 and 602 to carry hoop stress. Following this initial assembly step, two 180 degree segments, first outer ring segment 604 and second outer ring segment 606, are coupled to the ring created by first and second inner ring segments 600 and 602, and welded in place. The weld joint is formed along the two 360 degree seams between outer ring segments 604 and 606, and inner ring segments 600 and 602. Seal teeth 608 are finish machined following assembly and welding of segments 600, 602, 604, and 606 to ensure tooth alignment and tip runout requirements are met.
Segments 800 are assembled about shaft 30 (shown in
The seal assembly described herein enables installation of a separable seal on a shaft where integral teeth and/or a one piece ring are not usable. The seal assembly provides a 360 degree ring that can be installed on a completed shaft without needing clearance on either end for installation. The assembly provides different connection options depending on the specifications required.
While multiple inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the invent of embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure.
Examples are used to disclose the embodiments, including the best mode, and also to enable any person skilled in the art to practice the apparatus and/or method, including making and using any devices or systems and performing any incorporated methods. These examples are not intended to be exhaustive or to limit the disclosure to the precise steps and/or forms disclosed, and many modifications and variations are possible in light of the above teaching. Features described herein may be combined in any combination. Steps of a method described herein may be performed in any sequence that is physically possible.
All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases.
It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.
In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.
This application claims the benefit of U.S. Provisional Application No. 61/639403, filed Apr. 27, 2012, which is incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61639403 | Apr 2012 | US |
