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 .
Claims 1-8 and 10-20, 22 are currently pending. Claims 1-8, 10-16, and 22 are rejected. Claims 17-20 are withdrawn from consideration.
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on March 09, 2026, which refers to the filing of March 04, 2026, has been entered.
Response to Arguments
Applicant's arguments, see Pg. 7-8 of the remarks, filed March 04, 2026, with respect to the rejections of Claims 1 and 8 have been fully considered but they are not persuasive.
Regarding Claims 1 and 8, as best understood, Applicant has amended the claims to include a limitation similar to previously presented Claim 21. Applicant argues Hall et al. (US 2018/0017065 A1), which was used as a teaching reference in the rejection of previously presented Claim 21, is in reference to a pocket formed in an airfoil, not a radially inner surface of the airfoil. The rejection of December 10, 2025 already acknowledges the teachings of Hall to be analogous art even though the exemplary embodiment is not specifically on a shaft (see Pg. 16). Particularly, the teachings of Hall are related to the effect to of a use of a pocket rather than a plain surface when positioning of the pyrotechnic charge as described in paragraph [0057] of Hall. A requirement to be on a “radially inner surface” is not required by the teachings of Hall to be applicable, since a rejection of obviousness is based upon a combination of teachings rather than individual references. The “radially inner” aspect has already been addressed as a rearrangement of parts rationale (see Pg. 6-7 of the Final Rejection). No arguments have been provided regarding this portion of the rejection. Please note MPEP 2144.04 states if “the applicant has demonstrated the criticality of a specific limitation, it would not be appropriate to rely solely on case law as rationale to support an obviousness rejection”. No evidence of such is currently on record.
No further arguments have been provided with respect to the remaining claims.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-4, 7, and 22 are rejected under 35 U.S.C. 103 as being unpatentable over Alam et al. (US 2007/0009360 A1), hereinafter Alam, in view of Baehmann et al. (US 2014/0341715 A1), hereinafter Baehmann, Weng et al. (CN115524128A), hereinafter Weng, and Hall et al. (US 2018/0017065 A1), hereinafter Hall. A copy of Weng was provided with the IDS of February 14, 2024. References to the text of Weng will refer to the machine translation provided with the action of July 23, 2025.
Regarding Claim 1, interpreting “centering feature” under 35 U.S.C. 112(f) (see Pg. 4-5 of Non-Final of November 04, 2024) to be a lip or equivalents thereof as recited in paragraphs [0035-0036] of the Specification filed February 14, 2024, Figures 1A-B of Alam teach a spool of a gas turbine engine (see paragraph [0014]), comprising: an outer shaft assembly (interpretable as portions of 12a-c) disposed at and configured to rotate about an engine central longitudinal axis (X), the outer shaft assembly secured to two or more rotating components (12a, 12c) of the gas turbine engine, the outer shaft assembly including: a first shaft portion including a first shaft body (any body portion of the first shaft portion); a second shaft portion, the first shaft portion axially overlapping the second shaft portion at a shaft joint (at contact between first shaft portion and second shaft portion); wherein the first shaft portion includes a centering feature (axial overlap between first and second shaft portions) disposed at the shaft joint configured to radially center (due to the axial overlap preventing radial motion) the second shaft portion relative to the first shaft portion; and a tie shaft (14) concentric with and radially inboard of the outer shaft assembly, the tie shaft (14) configured to apply an axially compressive load on the outer shaft assembly (via 16) [0045-0047]. See also annotated Figure 1A’ below. Either the left or right pairs of marked portions are interpretable as first/second shaft portions. Out of each pair respectively, the claim does not limit which is considered the first or second. Note the limitation of wherein separating the tie shaft releases the axially compressive load thus allowing the uncoupling of the first shaft portion from the second shaft portion is treated as intended use of the claimed structure. Paragraph [0047] describes the axially compressive loading due to the tie shaft (14) when the shaft is not separated, i.e. the shaft is not broken.
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Alam does not expressly teach wherein the centering feature radially protrudes from the first shaft body as claimed. However, such a centering feature would have been obvious in view of Baehmann.
Figures 1-2 and 3 of Baehmann teach shaft assemblies with centering features (32, 132) of portions (24, 124) used in conjunction with an axially overlapping portion (28, unlabeled in Figure 3) [0032-0034, 0046]. In the Figure 1-2 embodiment, the centering feature (32) does not appear to protrude radially from the remainder of the portion (24). In the Figure 3 embodiment, centering feature (132) radially protrudes from the rest of portion (124). In both embodiments, the centering feature (32, 132) still assists in supporting the connection regardless of the change in shape. Thus, one of ordinary skill simply substituting one shape for another would expect for the centering feature to still function.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the spool taught by Alam by simply substituting the centering feature for one that radially protrudes from the first shaft body as exemplified by Baehmann, predictably resulting in the centering feature still functioning similarly.
Alam and Baehmann do not expressly teach a pyrotechnic charge configured to separate the tie shaft as claimed. However, a charge would have been obvious in view of Weng.
Figures 2-4 of Weng teach a shaft assembly having a pyrotechnic charge (16) configured to separate the shaft (11, 12). Weng explains the difficulty of simulating a shaft fracture event and how traditional cutting methods result in complexity and accuracy problems [n0005-n0006]. Weng proposes placing charge in the form of explosives at preset locations that can be detonated when the shaft reaches a preset rotation speed. The charge allows for a convenient, low-cost way to simulate a fracture at a specified location and speed [n0007-n0008, n0032-n0033].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the spool taught by Alam-Baehmann with a pyrotechnic charge configured to separate the tie shaft as suggested by Weng, to provide the benefit of having a convenient, low-cost way to simulate a fracture in the spool.
Alam, Baehmann, and Weng do not expressly teach the pyrotechnic charge is disposed in an inner surface pocket of the tie shaft as claimed. However, a pocket would have been obvious in view of Hall.
Figure 12 of Hall teaches an arrangement where a pyrotechnic charge is used to simulate the failure of an airfoil (Abstract). The charge (114) is disposed in a surface pocket (140) of the blade. The pocket (140) provides a surface for interfacing of the charge and its related components. The pocket also strategically weakens the blade at the portion where separation is desired [0057]. While not specifically on a shaft, the teachings of Hall are considered analogous art since they are in the same field of endeavor (testing with explosives) as the instant application.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the spool taught by Alam-Baehmann-Weng the pyrotechnic charge is disposed in an inner surface pocket of the tie shaft as suggested by Hall, to provide the benefit of producing an interfacing surface for the charge and strategically weakening where the charge is placed to facilitate separation at the desired location.
Alam, Baehmann, Weng, and Hall do not expressly teach the pyrotechnic charge is disposed at a location formed in a radially inner surface of the tie shaft as claimed.
However, the courts have held various practices to be routine expedients, requiring only ordinary skill. One such practice includes the rearrangement of parts. The courts have held unpatentable the shifting of position that does not modify the operation of a device, and a particular placement being merely a matter of design choice (see MPEP 2144.04, VI, C). Regarding the instant application, Weng desires to place pyrotechnic charges at a preset shaft breakage position (9) illustrated in Figure 1 [n0031]. This is illustrated as an axial positioning without regards to whether it is on the inner or outer portion of the shaft. It is after the preset position is determined that the charges are placed on the outer peripheral wall of the rotor shaft, as exemplified in the described embodiments [n0031-n0032]. There is currently no evidence of record that the placement of the charge modifies the operation of the device, since as just discussed, Weng is concerned with the placement being at the predicated preset shaft breakage position (9) that is illustrated in terms of axial positioning. As such, rearranging the charge to be on the inside or outside is considered merely a matter of design choice, since the resulting simulated breakage is still at the same axial location.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the spool taught by Alam-Baehmann-Weng-Hall such that the location of the pyrotechnic charge is formed in a radially inner surface of the tie shaft, since rearranging the charge to be on the inside or outside is considered merely a matter of design choice.
Regarding Claim 2, Alam, Baehmann, Weng, and Hall teach the spool as set forth in Claim 1.
Figures 1A-B of Alam teach a nut (16) applied to the tie shaft (14) to apply the compressive load [0047-0048]. Nut (16) is described as applying an axial loading.
Regarding Claim 3, Alam, Baehmann, Weng, and Hall teach the spool as set forth in Claim 1.
Figures 1A-B of Alam teach wherein the centering feature includes an outer diameter lip of the first shaft portion that overlaps the second shaft portion. See annotated Figure 1A’ above. For the left pair, the right portion is interpretable as the first shaft portion that overlaps the left second shaft portion. For the right pair, the left portion is interpretable as the first shaft portion that overlaps the right second shaft portion. The radially outer overlapping portion is interpreted as the claimed outer diameter lip.
Regarding Claim 4, Alam, Baehmann, Weng, and Hall teach the spool as set forth in Claim 1.
Figures 1A-B of Alam teach wherein the centering feature includes an inner diameter lip of the first shaft portion that axially overlaps the second shaft portion. See annotated Figure 1A’ above. For the left pair, the left portion is interpretable as the first shaft portion that overlaps the right second shaft portion. For the right pair, the right portion is interpretable as the first shaft portion that overlaps the left second shaft portion. The radially inner overlapping portion is interpreted as the claimed inner diameter lip. As noted in Baehmann above, having a shape is considered protruding radially appears to be a matter of simply substitution.
Regarding Claim 7, Alam, Baehmann, Weng, and Hall teach the spool as set forth in Claim 1.
Figures 1A-B of Alam teach wherein the tie shaft (14) is continuous and unbroken along an axial length of the outer shaft assembly.
Regarding Claim 22, Alam, Bahmann, Weng, and Hall teach the spool as set forth in Claim 1.
Alam, Bahmann, Weng, and Hall do not expressly teach wherein the pyrotechnic charge is disposed at a same axial position as the shaft joint as claimed.
However, as noted in Claim 1 above, the courts have held various practices to be routine expedients, requiring only ordinary skill. One such practice includes the rearrangement of parts. The courts have held unpatentable the shifting of position that does not modify the operation of a device, and a particular placement being merely a matter of design choice (see MPEP 2144.04, VI, C). Regarding the instant application, Weng desires to place pyrotechnic charges at a preset shaft breakage position (9) illustrated in Figure 1 [n0031]. In other words, the location is merely a preset axial position to be tested. There is currently no evidence of record that the placement of the charge modifies the operation of the device. As such, rearranging the charge to be at an axial location merely a matter of design choice of what breakage location is desired to be tested.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the spool taught by Alam-Baehmann-Weng-Hall such that the location of the pyrotechnic charge is formed in a radially inner surface of the tie shaft, since rearranging the charge to be at a particular axial position is merely a matter of design choice.
Claims 5-6 are rejected under 35 U.S.C. 103 as being unpatentable over Alam in view Baehmann, Weng, and Hall, as applied to Claim 1 above, and further in view of Walters et al. (US 2009/0025461 A1), hereinafter Walters.
Regarding Claim 5, Alam, Baehmann, Weng, and Hall teach the spool as set forth in Claim 1.
Alam does not expressly teach wherein the spool is a high pressure spool of a two-spool gas turbine engine. However, a high pressure spool would have been obvious in view of Walters.
Paragraph [0002-0003] of Alam describes the teachings as being related to a rotor assembly of a gas turbine engine. However, the disclosure does not provide much context in how the rotor assembly is implemented in a gas turbine engine. The exemplified structure is known structure of a high pressure spool as evidenced by Walter. Figure 1 of Walters schematically illustrates more structure of known gas turbine engines compared to what is illustrated in Alam. See also Figures 2-3. Impeller (32) and turbine (24) are analogous to the rotor stack in Figures 1A-B of Alam, as noted by impeller (32) being the same type of impeller as (12a) in Alam and rotors (30a, 30b) being the same type as (12c, 12d) in Alam. The spool connecting (32) and (24) is a high pressure spool of a two-spool gas turbine engine. This allows for the intended operation of the gas turbine engine such that the high pressure turbine (24) drives the high pressure compressor (22, 32 being a part of) through a high pressure spool and the low pressure turbine (26) drives the fan (12) through a low pressure spool. As described, the operation allows for the compressor section (14) to pressurize air, combustor (16) to ignite the compressed air, and the turbine section (18) to extract energy from the combustion gases [0028-0029]. Thus, Walters exemplifies how the spool taught by Alam would be implemented in a gas turbine engine for operation.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the spool taught by Alam-Baehmann-Weng-Hall such that the spool is a high pressure spool of a two-spool gas turbine engine as suggested by Walters, to provide the benefit of integrating the spool in a known gas turbine engine for successful operation.
Regarding Claim 6, Alam, Baehmann, Weng, Hall, and Walters teach the spool as set forth in Claim 5.
Figures 1A-B of Alam teach wherein the spool includes: an impeller (12a); and a turbine (12c-d); wherein the impeller (12a) is disposed at the first shaft portion extends axially rearwardly from the impeller (12a) and the second shaft portion extends axially forwardly from the turbine (12c-d). Referring to annotated Figure 1A’ above, the claim limits the first shaft portion to be the left (respective 12a or b portions) of each pair and the second shaft portion to be the right (respective 12b or 12c portions) of each pair.
Claims 8 and 10-16 are rejected under 35 U.S.C. 103 as being unpatentable over Alam in view of Baehmann, Walters, Weng, and Hall.
Regarding Claim 8, interpreting “centering feature” under 35 U.S.C. 112(f) (see Pg. 4-5 of Non-Final of November 04, 2024) to be a lip or equivalents thereof as recited in paragraphs [0035-0036] of the Specification filed February 14, 2024, Figures 1A-B of Alam teaches a gas turbine engine (see paragraphs [0002-0003]) comprising: at least one spool (10), the at least one spool including: a turbine (12c, d); a compressor (12a) operable connected to and driven by rotation of the turbine (12c, d); an outer shaft assembly (interpretable as portions of 12a, b, c) including: a first shaft portion connected to the compressor, the first shaft portion including a first shaft body (any body portion of the first shaft portion); a second shaft portion connected to the turbine, the first shaft portion axially overlapping the second shaft portion at a shaft joint; wherein the first shaft portion includes a centering feature (axial overlap between first and second shaft portions) disposed at the shaft joint configured to radially center (due to the axial overlap preventing radial motion) the second shaft portion relative to the first shaft portion; a tie shaft (14) concentric with and radially inboard of the outer shaft assembly (interpretable as portions of 12a-c), the tie shaft (14) configured to apply an axially compressive load on the outer shaft assembly (via 16) [0045-0047]. See also annotated Figure 1A’ above. The first shaft portion is the left (respective 12a or b portions) of each pair of marked portions and the second shaft portion is the right (respective 12b or 12c portions) of each pair. Note the limitation of wherein separating the tie shaft releases the axially compressive load thus allowing the uncoupling of the first shaft portion from the second shaft portion is treated as intended use of the claimed structure. Paragraph [0047] describes the axially compressive loading due to the tie shaft (14) when the shaft is not separated, i.e. the shaft is not broken.
Alam does not expressly teach wherein the centering feature radially protrudes from the first shaft body as claimed. However, such a centering feature would have been obvious in view of Baehmann.
Figures 1-2 and 3 of Baehmann teach shaft assemblies with centering features (32, 132) of portions (24, 124) used in conjunction with an axially overlapping portion (28, unlabeled in Figure 3) [0032-0034, 0046]. In the Figure 1-2 embodiment, the centering feature (32) does not appear to protrude radially from the remainder of the portion (24). In the Figure 3 embodiment, centering feature (132) radially protrudes from the rest of portion (124). In both embodiments, the centering feature (32, 132) still assists in supporting the connection regardless of the change in shape. Thus, one of ordinary skill simply substituting one shape for another would expect for the centering feature to still function.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the spool taught by Alam by simply substituting the centering feature for one that radially protrudes from the first shaft body as exemplified by Baehmann, predictably resulting in the centering feature still functioning similarly.
Alam does not expressly teach a combustor; the turbine configured to be driven by products of the combustor as claimed. However, a combustor would have been obvious in view of Walters.
Paragraph [0002-0003] of Alam describes the teachings as being related to a rotor assembly of a gas turbine engine. However, the disclosure does not provide much context in how the rotor assembly is implemented in a gas turbine engine. The exemplified structure is known structure of a high pressure spool as evidenced by Walter. Figure 1 of Walters schematically illustrates more structure of known gas turbine engines compared to what is illustrated in Alam. See also Figures 2-3. Impeller (32) and turbine (24) are analogous to the rotor stack in Figures 1A-B of Alam, as noted by impeller (32) being the same type of impeller as (12a) in Alam and rotors (30a, 30b) being the same type as (12c, 12d) in Alam. In Figure 1 of Walters, the gas turbine comprises a combustor (16); the turbine (24) configured to be driven by products of the combustor (16). This is known operation of a gas turbine that allows the turbine section (18) to extract energy from the combustion gases [0028-0029]. Thus, Walters exemplifies the known operation of a gas turbine engine.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the gas turbine engine taught by Alam-Baehmann with a combustor; the turbine configured to be driven by products of the combustor as suggested by Walters, to provide the benefit of allowing the gas turbine engine to operate and extract energy in a known fashion.
Alam, Baehmann, and Walters do not expressly teach a pyrotechnic charge configured to separate the tie shaft as claimed. However, a charge would have been obvious in view of Weng.
Figures 2-4 of Weng teach a shaft assembly having a pyrotechnic charge (16) configured to separate the shaft (11, 12). Weng explains the difficulty of simulating a shaft fracture event and how traditional cutting methods result in complexity and accuracy problems [n0005-n0006]. Weng proposes placing charges in the form of explosives at preset locations that can be detonated when the shaft reaches a preset rotation speed. The charge allows for a convenient, low-cost way to simulate a fracture at a specified location and speed [n0007-n0008, n0032-n0033].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the gas turbine engine taught by Alam-Baehmann-Walters with a pyrotechnic charge configured to separate the tie shaft as suggested by Weng, to provide the benefit of having a convenient, low-cost way to simulate a fracture in the gas turbine spool.
Alam, Baehmann, Walters, and Weng do not expressly teach the pyrotechnic charge is disposed in an inner surface pocket of the tie shaft as claimed. However, a pocket would have been obvious in view of Hall.
Figure 12 of Hall teaches an arrangement where a pyrotechnic charge is used to simulate the failure of an airfoil (Abstract). The charge (114) is disposed in a surface pocket (140) of the blade. The pocket (140) provides a surface for interfacing of the charge and its related components. The pocket also strategically weakens the blade at the portion where separation is desired [0057]. While not specifically on a shaft, the teachings of Hall are considered analogous art since they are in the same field of endeavor (testing with explosives) as the instant application.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the gas turbine engine taught by Alam-Baehmann-Walters-Weng the pyrotechnic charge is disposed in an inner surface pocket of the tie shaft as suggested by Hall, to provide the benefit of producing an interfacing surface for the charge and strategically weakening where the charge is placed to facilitate separation at the desired location.
Alam, Baehmann, Walters, Weng, and Hall do not expressly teach the pyrotechnic charge is disposed at a location formed in a radially inner surface of the tie shaft as claimed.
However, the courts have held various practices to be routine expedients, requiring only ordinary skill. One such practice includes the rearrangement of parts. The courts have held unpatentable the shifting of position that does not modify the operation of a device, and a particular placement being merely a matter of design choice (see MPEP 2144.04, VI, C). Regarding the instant application, Weng desires to place pyrotechnic charges at a preset shaft breakage position (9) illustrated in Figure 1 [n0031]. This is illustrated as an axial positioning without regards to whether it is on the inner or outer portion of the shaft. It is after the preset position is determined that the charges are placed on the outer peripheral wall of the rotor shaft, as exemplified in the described embodiments [n0031-n0032]. There is currently no evidence of record that the placement of the charge modifies the operation of the device, since as just discussed, Weng is concerned with the placement being at the predicated preset shaft breakage position (9) that is illustrated in terms of axial positioning. As such, rearranging the charge to be on the inside or outside is considered merely a matter of design choice, since the resulting simulated breakage is still at the same axial location.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the gas turbine engine taught by Alam-Baehmann-Walters-Weng-Hall such that the location of the pyrotechnic charge is formed in a radially inner surface of the tie shaft, since rearranging the charge to be on the inside or outside is considered merely a matter of design choice.
Regarding Claim 10, Alam, Baehmann, Walters, Weng, and Hall teach the gas turbine engine as set forth in Claim 8.
Figure 1B of Alam teaches further comprising a nut (16) applied to the tie shaft (14) to apply the compressive load [0047-0048]. Nut (16) is described as applying an axial loading.
Regarding Claim 11, Alam, Baehmann, Walters, Weng, and Hall teach the gas turbine engine as set forth in Claim 10.
Figure 1B of Alam teaches wherein application of the nut (16) to the tie shaft (14) applies a tensile load to the tie shaft (14) [0048].
Regarding Claim 12, Alam, Baehmann, Walters, Weng, and Hall teach the gas turbine engine as set forth in Claim 8.
Figures 1A-B of Alam teach wherein the tie shaft (14) is continuous and unbroken along an axial length of the outer shaft assembly.
Regarding Claim 13, Alam, Baehmann, Walters, Weng, and Hall teach the gas turbine engine as set forth in Claim 8.
Figures 1A-B of Alam teach wherein the centering feature includes an outer diameter lip of the first shaft portion that overlaps the second shaft portion. See annotated Figure 1A’ above. For the left pair, the right portion is interpretable as the first shaft portion that overlaps the left second shaft portion. For the right pair, the left portion is interpretable as the first shaft portion that overlaps the right second shaft portion. The radially outer overlapping portion is interpreted as the claimed outer diameter lip.
Regarding Claim 14, Alam, Baehmann, Walters, Weng, and Hall teach the gas turbine engine as set forth in Claim 8.
Figures 1A-B of Alam teach wherein the centering feature includes an inner diameter lip of the first shaft portion that overlaps the second shaft portion. See annotated Figure 1A’ above. For the left pair, the left portion is interpretable as the first shaft portion that overlaps the right second shaft portion. For the right pair, the right portion is interpretable as the first shaft portion that overlaps the left second shaft portion. The radially inner overlapping portion is interpreted as the claimed inner diameter lip. As noted in Baehmann above, having a shape is considered protruding radially appears to be a matter of simply substitution.
Regarding Claim 15, Alam, Baehmann, Walters, Weng, and Hall teach the gas turbine engine as set forth in Claim 8.
The modification in Claim 8 by Walters results wherein the spool is a high pressure spool of a two-spool gas turbine engine, as exemplified by Walters. Figure 1 of Walters schematically illustrates more structure of known gas turbine engines compared to what is illustrated in Alam. See also Figures 2-3. Impeller (32) and turbine (24) are analogous to the rotor stack in Figures 1A-B of Alam, as noted by impeller (32) being the same type of impeller as (12a) in Alam and rotors (30a, 30b) being the same type as (12c, 12d) in Alam. The spool connecting (32) and (24) is a high pressure spool of a two-spool gas turbine engine. This allows for the intended operation of the gas turbine engine such that the high pressure turbine (24) drives the high pressure compressor (22, 32 being a part of) and the low pressure turbine (26) drives the fan (12). As described, the operation allows for the compressor section (14) to pressurize air, combustor (16) to ignite the compressed air, and the turbine section (18) to extract energy from the combustion gases [0028-0029].
Regarding Claim 16, Alam, Baehmann, Walters, Weng, and Hall teach the gas turbine engine as set forth in Claim 8.
Figures 1A-B of Alam teach wherein the compressor (12a) is an impeller. This is clearly illustrated by its shaping.
Claim 22 is rejected under 35 U.S.C. 103 as being unpatentable over Alam in view Baehmann, Weng, and Hall, as applied to Claim 1 above, and further in view of Gurvich et al. (US 2022/0026308 A1), hereinafter Gurvich. Claim 22 is rejected again for purposes of expediting prosecution, assuming evidence of the criticality of the axial positioning is provided.
Regarding Claim 22, Alam, Baehmann, Weng, and Hall teach the spool as set forth in Claim 1.
Alam, Baehmann, Weng, and Hall do not expressly teach wherein the pyrotechnic charge is disposed at a same axial position as the shaft joint as claimed. However, such a positioning would have been obvious in view of Gurvich.
Figure 2 of Gurvich teaches a spool wherein a load applicator (34, see [0092-0093]) is disposed at a same axial position as the shaft joint (location of cross-sectional view in Figure 2). The load applicator is placed to test particularly at the joint because it would allow testing of the joint and such a location is recognized to be the weakest point of the spool [0003]. In other words, a fracture is likely to occur there. In the instance of the combination, the load applicator is analogous to the pyrotechnic charge as introduced in Claim 1 by Weng, which provides a separating force for the shaft (Weng, [n0007-n0008]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the spool taught by Alam-Baehmann-Weng-Hall such that the pyrotechnic charge is disposed at a same axial position as the shaft joint as suggested by Gurvich, to provide the benefit of allowing testing particularly the joint, and since the joint is recognized to be the weakest point of the spool.
Conclusion
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/ELTON K WONG/Primary Examiner, Art Unit 3745
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