DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Election/Restrictions
Applicant’s election without traverse of Species VI drawn to Fig. 5, 6a and 6b in the reply filed on 10/21/2025 is acknowledged.
Claims 7-9 and 14 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected species, there being no allowable generic or linking claim. Additionally claims 2 and 3 are withdrawn from further consideration as they are also drawn to nonelected species (Species VII and VIII and Species I-V, respectively). Election was made without traverse in the reply filed on 10/21/2025.
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
Claim(s) 1, 4, 6, 10-11, and 19 is/are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Bidkar et al. (US 11,047,481; hereinafter Bidkar).
Regarding claim 1, Bidkar (Fig. 5-7) discloses a seal assembly for a gas turbine, the seal assembly comprising: a seal case; and a seal shoe (1502) arranged within the seal case, the seal shoe (1502) including (1) a main seal portion that is capable of engaging with a radial bearing engagement portion of a rotor shaft, (2) a radial bearing surface (120) that engages with the radial bearing engagement portion of the rotor shaft, (3) at least one hydrodynamic lift cavity (1722) extending through the radial bearing surface (120), and (4) at least one airflow passage (1700 and 1702) extending from a first side of the seal shoe (1502) through the at least one hydrodynamic lift cavity (1722) and providing airflow communication between the first side of the seal shoe (1502) and the at least one hydrodynamic lift cavity (1722). Refer to Fig. I below.
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Fig. I. Bidkar, Fig. 6 (Annotated)
Regarding claim 4, Bidkar discloses the seal assembly according to claim 1, wherein Bidkar (Fig. 1-2 and 5-7; Col. 3, lines 17-25) further discloses the seal shoe (1502) is additively manufactured.
Regarding claim 6, Bidkar discloses the seal assembly according to claim 1, wherein Bidkar (Fig. 1-2 and 5-7) further discloses that the seal assembly is configured for use in a gas turbine (Col. 1, lines 20-29), the first side of the seal shoe (1502) is a high pressure side (Phigh), and a second side of the seal shoe (1502) is a low pressure side (Plow), and, the seal assembly is configured to provide a leakage airflow to the at least one airflow passage (1700 and 1702) and to the at least one hydrodynamic lift cavity (1722) to provide a hydrodynamic lift function between the seal shoe (1502) and the radial bearing engagement portion (104) of the rotor shaft.
Regarding claim 10, Bidkar discloses the seal assembly according to claim 1, wherein Bidkar (Fig. 1-2 and 5-7) further discloses that the at least one hydrodynamic lift cavity (1722) comprises a plurality of hydrodynamic lift cavities (1722 - positions identified below in annotated Fig. 1) including a first hydrodynamic lift cavity and a second hydrodynamic lift cavity spaced apart in a first direction (108) from the first hydrodynamic lift cavity. Refer to Fig. II below.
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Fig. II. Bidkar, Fig. 1 (Annotated)
Regarding claim 11, Bidkar discloses the seal assembly according to claim 10, wherein Bidkar (Fig. 1-2 and 5-7) further discloses that the plurality of hydrodynamic lift cavities (1722) includes a first plurality of the first hydrodynamic lift cavities spaced apart from each other in a third direction (114), and a second plurality of the second hydrodynamic lift cavities spaced apart from each other in the third direction (114). Refer to Fig. III below.
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Fig. III. Bidkar, Fig. 1 (Annotated)
Regarding claim 19, Bidkar discloses the seal assembly according to claim 1, wherein Bidkar (Fig. 1-2 and 5-7) further discloses that the at least one hydrodynamic lift cavity includes a plurality of hydrodynamic lift cavities including a first group of hydrodynamic lift cavities arranged, in a first direction (108), at a first distance from the first side of the seal shoe, a second group of hydrodynamic lift cavities arranged, in the first direction, at a second distance greater than the first distance from the first side of the seal shoe, and a third group of hydrodynamic lift cavities arranged, in the first direction, at a third distance greater than the second distance from the first side of the seal shoe. Refer to Fig. I and IV below.
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Fig. IV. Bidkar, Fig. 1 (Annotated)
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claim(s) 5 is/are rejected under 35 U.S.C. 103 as being unpatentable over Bidkar et al. (US 11,047,481; hereinafter Bidkar) in view of Johnson et al. (US 2022/0389825; hereinafter Johnson).
Regarding claim 5, Bidkar discloses the seal assembly according to claim 1, but fails to explicitly disclose that the seal assembly is arranged at an inner end of at least one stator vane connected to a stator housing surrounding the rotor shaft.
Johnson (Fig. 2) teaches that it is well known to position a seal assembly between an inner end of a turbine vane (72) and a rotor shaft (51). Johnson (Paragraph 0002, lines 15-18) teaches that a seal assembly can be used to reduce leakage fluids between the rotor and stator. It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify Bidkar by specifically positioning the seal assembly between the inner end of a stator vane and a rotor shaft, as taught by Johnson, in order to reduce leakage of fluids between the rotor and stator and since Bidkar already generally teaches positioning the seal assembly between a rotor and stator.
Claim(s) 15 and 17 is/are rejected under 35 U.S.C. 103 as being unpatentable over Bidkar et al. (US 11,047,481; hereinafter Bidkar).
Regarding claim 15, Bidkar discloses the seal assembly according to claim 10, wherein Bidkar (Fig. 1-2 and 5-7) further discloses that the plurality of hydrodynamic lift cavities (1722) further includes a third hydrodynamic lift cavity spaced apart in a second direction (108) from the first hydrodynamic lift cavity. Refer to Fig. II above.
Bidkar fails to disclose a fourth hydrodynamic lift cavity spaced apart in the second direction from the second hydrodynamic lift cavity.
Although Bidkar fails to disclose a fourth hydrodynamic lift cavity spaced apart in the second direction from the second hydrodynamic lift cavity, it has been held in re Harza, 274 F.2d 669, 124 USPQ 378 (CCPA 1960), “the duplication of parts has no patentable significance unless a new and unexpected result is produced” (see MPEP 2144.04, Section VI(B)). In the instant claim, additional rows of hydrodynamic lift cavities produce the expected result of more evenly distributed fluid between the seal segments and rotor. So it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify Bidkar by adding a row of fourth hydrodynamic lift cavities spaced apart in the second direction from the second hydrodynamic lift cavity since it has been held in re Harza, 274 F.2d 669, 124 USPQ 378 (CCPA 1960), “the duplication of parts has no patentable significance unless a new and unexpected result is produced”.
Regarding claim 17, Bidkar, as modified, discloses the seal assembly according to claim 15, wherein Bidkar (Fig. 1-2 and 5-7), as modified, further discloses that the plurality of hydrodynamic lift cavities (1722 - positions identified in annotated Fig. 1 above) includes a first plurality of the first hydrodynamic lift cavities (in line with the first hydrodynamic lift cavity identified in Fig. II) spaced apart from each other in a third direction (114), and a second plurality of the second hydrodynamic lift cavities (in line with the second hydrodynamic lift cavity identified in Fig. II) spaced apart from each other in the third direction (114), a third plurality of the third hydrodynamic lift cavities (in line with the third hydrodynamic lift cavity identified in Fig. II) spaced apart from each other in the third direction (114), and a fourth plurality of the fourth hydrodynamic lift cavities (refer to the rejection of claim 15) spaced apart from each other in the third direction (114). Refer to Fig. II above.
Allowable Subject Matter
Claims 12, 16, 18, and 20 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
The following is a statement of reasons for the indication of allowable subject matter:
Regarding claim 12:
Closest prior art: Bidkar et al. (US 11,047,481; hereinafter Bidkar)
Bidkar discloses the seal assembly according to claim 10.
The closest prior art fails to disclose or suggest that the at least one airflow passage includes a plurality of branched airflow passages including a first branched airflow passage providing airflow communication with the first hydrodynamic lift cavity, and a second branched airflow passage providing airflow communication with the second hydrodynamic lift cavity.
Regarding claim 16:
Closest prior art: Bidkar et al. (US 11,047,481; hereinafter Bidkar)
Bidkar discloses that the first hydrodynamic lift cavity and the second hydrodynamic lift cavity are open hydrodynamic lift cavities having a first side that is open through the radial bearing surface.
The closest prior art fails to disclose or suggest that the third hydrodynamic lift cavity and the fourth hydrodynamic lift cavity are closed hydrodynamic lift cavities contained within the seal shoe.
Regarding claim 18:
Closest prior art: Bidkar et al. (US 11,047,481; hereinafter Bidkar)
Bidkar discloses that each of the first hydrodynamic lift cavities and the second hydrodynamic lift cavities are open hydrodynamic lift cavities having a first side that is open through the radial bearing surface.
The closest prior art fails to disclose or suggest that each of the third hydrodynamic lift cavities and the fourth hydrodynamic lift cavities are closed hydrodynamic lift cavities contained within the seal shoe.
Regarding claim 20:
Closest prior art: Bidkar et al. (US 11,047,481; hereinafter Bidkar)
Bidkar discloses that each of the first group of hydrodynamic lift cavities and the third group of hydrodynamic lift cavities includes an open hydrodynamic lift cavity having a radially inner side extending through the radial bearing surface.
The closest prior art fails to disclose or suggest that each of the first group of hydrodynamic lift cavities and the third group of hydrodynamic lift cavities also includes a closed hydrodynamic lift cavity arranged within the seal shoe radially outward of the open hydrodynamic lift cavity, and the second group of hydrodynamic lift cavities includes a first closed hydrodynamic lift cavity arranged within the seal shoe radially outward of the radial bearing surface and a second closed hydrodynamic lift cavity arranged radially outward of the first closed hydrodynamic lift cavity.
Pertinent Prior Art
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Sen et al. (US 2019/0211699) discloses a seal positioned between the inner end of a stator vane and a rotor.
Contact Information
Any inquiry concerning this communication or earlier communications from the examiner should be directed to DANIELLE M CHRISTENSEN whose telephone number is (571)270-3275. The examiner can normally be reached M-F 9-5 PM.
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/Danielle M. Christensen/Examiner, Art Unit 3745