GE AVIO S.r.l.Download PDFPatent Trials and Appeals BoardSep 1, 20212021001833 (P.T.A.B. Sep. 1, 2021) Copy Citation UNITED STATES PATENT AND TRADEMARK OFFICE UNITED STATES DEPARTMENT OF COMMERCE United States Patent and Trademark Office Address: COMMISSIONER FOR PATENTS P.O. Box 1450 Alexandria, Virginia 22313-1450 www.uspto.gov APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO. 15/348,657 11/10/2016 Daniele COUTANDIN 316450-US-3/GECV-1843 6106 122218 7590 09/01/2021 Dority & Manning, P.A. and GEC-Aviation Post Office Box 1449 Greenville, SC 29602-1449 EXAMINER MARIEN, ANDREW JAMES ART UNIT PAPER NUMBER 3745 NOTIFICATION DATE DELIVERY MODE 09/01/2021 ELECTRONIC Please find below and/or attached an Office communication concerning this application or proceeding. The time period for reply, if any, is set in the attached communication. Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the following e-mail address(es): oc.prosecution@ge.com usdocketing@dority-manning.com PTOL-90A (Rev. 04/07) UNITED STATES PATENT AND TRADEMARK OFFICE ____________________ BEFORE THE PATENT TRIAL AND APPEAL BOARD ____________________ Ex parte DANIELE COUTANDIN ____________ Appeal 2021-001833 Application 15/348,657 Technology Center 3700 ____________ Before JENNIFER D. BAHR, CARL M. DEFRANCO, and LISA M. GUIJT, Administrative Patent Judges. GUIJT, Administrative Patent Judge. DECISION ON APPEAL STATEMENT OF THE CASE Appellant1 seeks our review under 35 U.S.C. § 134(a) of the rejection of claims 1–6, 10, and 14. We have jurisdiction under 35 U.S.C. § 6(b). We AFFIRM. 1 We use the word “Appellant” to refer to “applicant” as defined in 37 C.F.R. § 1.42. Appellant identifies the General Electric Company as the real party in interest. Appeal Br. 3. Appeal 2021-001833 Application 15/348,657 2 THE INVENTION Appellant’s invention relates to “a gas turbine engine stage provided with a labyrinth seal.” Spec. 1:7–9. Claims 1, 5, and 14 are the independent claims on appeal. Claim 1, reproduced below, is illustrative of the subject matter on appeal. 1. A gas turbine engine stage, the stage extending along a rotation axis and comprising: a static part; a rotating part; and a labyrinth seal arranged radially between said static part and rotating part and comprising: a) a layer of abradable material, which is arranged on said static part, is continuous in the axial direction and, in an initial assembly configuration, is radially delimited by a cylindrical surface having a constant diameter; and b) at least three tabs, that radially project from said rotating part, are axially set apart from each other and end with respective tips, directly facing said layer of abradable material in the radial direction; characterized in that said three tabs are constituted by: first and second side tabs and one intermediate tab, which is arranged in an intermediate axial position between said side tabs and has a smaller radial height than that of said side tabs; the layer of abradable material is radially defined by a shaped surface defining first and second seats, which have been fretted by the tips of said first and second side tabs during operation and are axially separated from each other by a step of said shaped surface, wherein the first seat is positioned between Appeal 2021-001833 Application 15/348,657 3 the step and a forward portion of the abradable material which is axially forward of the first side tab and which extends radially inward past a tip of the first side tab towards the labyrinth seal and the second seat is positioned between the step and an aft portion of the abradable material which is axially aft of the second side tab and which extends radially inward past a tip of the second side tab towards the labyrinth seal; and the tip of said intermediate tab is arranged at said step and wherein the forward portion of the abradable material has a height relative to a bottom of the first seat greater than a height of the step and wherein the aft portion of the abradable material has a height relative to a bottom of the second seat greater than a height of the step. THE REJECTIONS The Examiner relies upon the following as evidence in support of the rejections: Name Reference(s) Date Naudet US 4,604,030 Aug. 5, 1986 Mason US 5,096,376 Mar. 17, 1992 Nakano US 2011/0068539 A1 Mar. 24, 2011 Zeng US 2012/0043728 A1 Feb. 23, 2012 The following rejections are before us for review: I. Claims 1, 4, 5, 10, and 14 stand rejected under 35 U.S.C. § 103 as unpatentable over Naudet, Nakano, and Mason. II. Claims 2, 3, and 6 stand rejected under 35 U.S.C. § 103 as unpatentable over Naudet, Nakano, Mason,2 and Zeng. 2 We view the omission of Mason in the rejection of the dependent claims as a typographical error, as the rejection cites Naudet and Nakano “as applied to claims 1 and 5,” and Naudet and Nakano are applied in combination with Mason in rejecting claims 1 and 5. Final Act. 13–14. Logically, the dependency of claims 2, 3, and 6 on independent claims 1 and 5 necessitates Appeal 2021-001833 Application 15/348,657 4 OPINION Rejection I Regarding independent claim 1, the Examiner finds that Naudet discloses, inter alia, a gas turbine engine stage with a labyrinth seal comprising a layer of abradable material arranged on a static part and at least three tabs radially projecting from a rotating part, as claimed. Final Act. 3–4 (citing, e.g., Naudet Fig. 1). The Examiner determines that Naudet does not disclose that the intermediate tab has a smaller radial height than the side tabs, and thus, also the differences in the opposing abraded material relative to the height of the forward and aft portions as compared to a step, as required by claim 1. Id. at 5–6. The Examiner relies on Nakano disclosing, with reference to Figure 8, an intermediate tab (i.e., fin 72) having a smaller radial height than the side tabs (i.e., fins 72), and reasons that it would have been obvious to have modified Naudet’s intermediate tab to have a smaller radial height than the side tabs, as taught in Nakano, “to enhance seal performance.” Final Act. 6 (citing Nakano ¶ 18). The Examiner relies on Mason for teaching that “teeth cut into the abradable seal land during relative motions between the rotating and non- rotating engine components,” such that “[i]t is known . . . to make a seal and to reduce clearances [such] that the tab structure[] cut[s] into the abradable material.” Id. at 6–7 (citing Mason 1:50–55). The Examiner reasons that it would have been obvious “to have employ[ed] the teachings of Mason to the inclusion of Mason to render obvious the subject matter of claims 2, 3, and 6, which incorporate the limitations of claims 1 and 5. Appeal 2021-001833 Application 15/348,657 5 form seals with the teeth cutting into the abradable surface,” as applied to Naudet, to allow for “less damage to the engine and seal.” Id. at 7. Appellant argues that Naudet does not disclose forward and aft portions having a greater height than a height of a step, or an intermediate tab smaller than the first and second side tabs, but rather, Naudet discloses three tabs having the same height. Appeal Br. 10; see also Reply Br. 3. However, Appellant’s argument does not address the rejection as articulated by the Examiner in that the Examiner relies on Nakano, not Naudet, for disclosing these claim limitations and proposes modifying Naudet, in view of Nakano (and in further view of Mason) to result in the claimed subject matter. In other words, the Examiner responds correctly that non- obviousness cannot be established by attacking references individually where the rejection is based upon the teachings of a combination of references. In re Merck & Co., Inc., 800 F.2d 1091, 1097 (Fed. Cir. 1986); In re Keller, 642 F.2d 413, 425 (CCPA 1981). See Ans. 5. Appellant also argues that “Naudet does not disclose an abradable material having a shaped surface formed by the tips of the tabs.” Appeal Br. 10; see also Reply Br. 3. We are not persuaded by Appellant’s argument. First, Naudet discloses, with reference to a prior art labyrinth seal (i.e., without Naudet’s improvement) depicted in Figure 1, as relied on by the Examiner, that “wear seal 9 . . . cooperates in known manner, with lips 10 of a labyrinth seal rigid with the rotor, in order to reduce leakages resulting from the pressure difference existing across the stator stage.” Naudet 3:37– 41 (emphases added). Second, the Examiner further relies on Mason for teaching that a known manner of wearing the abradable material of a Appeal 2021-001833 Application 15/348,657 6 labyrinth seal is to have “[t]he teeth cut into the abradable seal land during relative motions between the rotating and non-rotating engine components,” such that “relative motion of the engine components can be accommodated without deforming the seal labyrinth teeth or damaging the engine.” Mason 1:50–55. Indeed, even Appellant’s Specification admits, in the Background of the Invention section, that [l]abyrinth seals are widely used between the stator and the rotor in aeronautical turbines, to limit the passage of gas streams from a higher pressure cavity to a lower pressure one. As is known, the labyrinth seal works by trying to create a narrow and tortuous passage for the drawn gas flow. . . . To maximize the sealing properties, labyrinth seals of the known type have one part on the stator, defined by a layer of abradable material . . . , and one part on the rotor, composed of a series of radial tabs . . . . . . . . The seal is configured such that, during operation, the tip of each radial tab frets a corresponding seat within the layer of abradable material, because of thermal expansion and of the relative rotation. Once the seats have been fretted, . . . [t]his configuration helps to increase the head losses and thereby improve the sealing properties, as it increases the tortuosity of the gas path and narrows as much as possible the passage cross section for these gases. . . . . This configuration also has the advantage that each radial tab digs its own seat in the most appropriate way on the basis of relative movements in each engine. Spec. 1:11–2:22 (emphases added). Thus, to the extent Naudet does not expressly disclose that the surface of wear seal 9 is shaped by being abraded by lips 10, the Examiner’s reliance on Mason for such a teaching is sufficient to render obvious this claimed subject matter. Appeal 2021-001833 Application 15/348,657 7 Appellant further argues that “Nakano discloses teeth of differing heights but does not disclose an abradable material with first and second seats,” as required by claim 1. Appeal Br. 10; see also Reply Br. 3. However, Appellant’s argument does not address the Examiner’s combination, wherein Nakano’s fins 72 of differing heights are used to modify Naudet’s lips 10 of a labyrinth seal, wherein the modified lips 10 of Naudet fret wear seal 9, in a known manner as evidenced by Mason, resulting in the claimed shaped surface on Naudet’s wear seal 9. Next, Appellant argues that Nakano teaches that “the abradable layer 85 need not be employed” (quoting Nakano ¶ 168) and also that Nakano’s “depressions and protrusions are pre-formed – not formed by tips of the tabs.” Appeal Br. 10–11. However, Appellant’s argument that Nakano’s abradable layer is optional or that, when employed, the abradable layer is pre-formed with steps corresponding to the fins does not apprise us of error in the Examiner’s finding that Nakano expressly discloses an intermediate fin (or tab) having a smaller radial height than the side fins (or tabs). Nor does Appellant apprise us of error in the Examiner’s reasoning that it would have been obvious to a person of ordinary skill, at the time of the invention, to have modified Naudet’s tabs of equal heights to have an intermediate tab having a smaller radial height than the side tabs, as taught by Nakano, to enhance seal performance, as Nakano specifically teaches that “depressions and protrusions may be formed [on the turbine rotor’s surface] and the length of the fins 71 may be adjusted in accordance therewith” because “[b]y doing so, . . . the steam passing through moves in a zig-zag manner, [such that] the sealing performance can be enhanced.” Nakano ¶ 167 (emphasis added); cf. Spec., supra (disclosing that known and widely used Appeal 2021-001833 Application 15/348,657 8 labyrinth seals use teeth to fret a corresponding abradable surface to increase the tortuosity of the gas path). Appellant further argues that “Nakano specifically tries to avoid contact between the fins and the surfaces 83, 85, 87.” Appeal Br. 10–12 (citing Nakano ¶¶ 17, 22, 29, 35, 139, 156, 163); Reply Br. 3. Appellant concludes that “Nakano teaches away from forming seats in an abradable material using the tips of tabs/fins” and “Nakano applies the abradable material to a pre-formed surface – the abradable material taking the shape of the pre-formed surface as opposed to being formed during operation by the tips of the tabs.” Appeal Br. 12–13. The Examiner points out correctly that, although Nakano discloses a preference for maintaining a gap between the fins and the opposing surface such that the fins do not come into contact with the opposing surface, Nakano also discloses that “the gap between the fins and the opposing surface can be set so as to allow contact therebetween to some extent.” Ans. 6 (citing Nakano ¶ 42). Notably, a reference does not teach away, however, if it merely expresses a general preference for an alternative invention but does not “criticize, discredit, or otherwise discourage” investigation into the invention claimed. In re Fulton, 391 F.3d 1195, 1201 (Fed. Cir. 2004). In other words, we agree with the Examiner that Nakano does not teach away from modifying the tabs of a labyrinth seal to have different heights to result in a more tortuous path when the tabs fret uneven surfaces in the abradable material of the opposing surface, in a labyrinth seal designed to perform as known and widely used, as evidenced by Mason. Finally, Appellant argues that Mason does not disclose the claimed forward and aft portions having a greater height than a seat in the shaped Appeal 2021-001833 Application 15/348,657 9 surface formed by the tips fretting the abradable surface material, as required by claim 1, or further, that “[o]ne skilled in the art would not interpret the Mason reference [as] teaching the use of relative motions between rotating and nonrotating engine components for a predetermined structure.” Appeal Br. 13; Reply Br. 3–4. The Examiner responds that “Mason teaches that the teeth cut into abradable material during relative motion between components” and Mason is relied upon for teaching “the intended purpose of the abradable material of the seals and further explain how the seals work.” Ans. 7. The Examiner explains that the Examiner’s combination, which involves modifying Naudet’s tabs, in view of Nakano, results in the claimed “seat and step structure during operation” (id.), in view of Mason’s teaching that tabs are known to be used to form a shaped surface in abraded material. Appellant’s argument does not apprise us of error in the Examiner’s finding relative to Mason or reasoning in view of Mason. Accordingly, we sustain the Examiner’s rejection of independent claim 1. Appellant relies on the same arguments for the patentability of independent claims 5 and 14, and also dependent claims 4 and 10, as relied on for the patentability of independent claim 1 supra. Therefore, for essentially the same reasons as set forth supra, we also sustain the Examiner’s rejection of independent claims 5 and 14, and dependent claims 4 and 10. Appeal Br. 14–16. Rejection II Appellant relies on the same arguments for the patentability of dependent claims 2, 3, and 6 as relied on for the patentability of independent claim 1 supra and as also applied to independent claim 5. Appeal Br. 16. Appeal 2021-001833 Application 15/348,657 10 Therefore, for essentially the same reasons as set forth supra, we also sustain the Examiner’s rejection of dependent claims 2, 3, and 6. CONCLUSION The Examiner’s decision rejecting claims 1–6, 10, and 14 is affirmed. DECISION SUMMARY In summary: Claim(s) Rejected 35 U.S.C. § Reference(s)/Basis Affirmed Reversed 1, 4, 5, 10, 14 103 Naudet, Nakano, Mason 1, 4, 5, 10, 14 2, 3, 6 103 Naudet, Nakano, Mason, Zeng 2, 3, 6 Overall Outcome 1–6, 10, 14 TIME PERIOD FOR RESPONSE No time period for taking any subsequent action in connection with this appeal may be extended under 37 C.F.R. § 1.136(a). See 37 C.F.R. § 1.136(a)(1)(iv). AFFIRMED Copy with citationCopy as parenthetical citation