DETAILED ACTION
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Objections
Claim 9 is objected to because of the following informalities:
Change line 2 accordingly: “comprises [[a]] the linear portion”. Appropriate correction is required.
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.
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.
Claim(s) 1, 3, 5-7, 9, 14, 15 and 18-20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Pub. No.: US 2018/0355877 A1 (Donnelly) in view of US Patent 3,632,223 (Hampton) and Pub. No.: US 2019/0226488 A1 (Tawfik), as evidenced by Pub. No.: US 2005/0106009 A1 (Cummings).
Regarding claim 1, Donnelly discloses (see figs. 1 and 10 wherein fig. 1 shows a view of a gas turbine engine 10 along with a prior art channel 70 and fig. 10 shows an embodiment of am annular diffuser channel 470 that is part of an overall gas turbine engine 10; see par. 46, top) a gas turbine engine 10 comprising:
an engine core 24,26,14,16,18 (see par. 2) defining an engine axis A and having a compressor section 24, a combustor section 14, and a turbine section 16 arranged along the engine axis A, with a core flow F in a core flow path 24,26,14,16 defined through (see fig. 1) the compressor section 24, the combustor section 14, and the turbine section 16;
a casing (see annotated figures below) of the compressor section 24 defining, in part, a portion (outer boundary thereof, see fig. 1) of the core flow path 10,14,16, with a bleed air cavity 62 defined between the casing (see annotated figures below) of the compressor section 24 and an engine housing (see annotated figure below);
an impeller 46 arranged between the compressor section 24 and the combustor section 16 along the core flow path 24,26,14,16, the impeller 46 comprising an impeller shroud 58, wherein the impeller 46 is configured to receive the core flow F from the compressor section 24 at an inlet (see annotated figure below) to the impeller 46 and direct a combustor portion (portion of core flow F entering impeller 46 blades 54 in fig. 1) of the core flow F to the combustor section 16;
a bleed aperture (see annotated figure below) defined axially between the casing (see annotated figures below) and the impeller shroud (58 shown in fig. 1 and see annotated figure below), wherein the bleed aperture (see annotated figure below) is defined as a circumferential slot (the bleed aperture is the inlet to the diffuser channel 470 that is an annular channel 470 and thus the bleed aperture is a circumferential slot extending circumferentially) that is continuous (it is annular and thus continuous) about a circumference of the engine core (see par. 46, top: “The compressor casing 428 includes a continuous annular bleed slot 470 disposed around its circumference” wherein slot 470 is the claimed diffuser channel); and
a bleed flow extension (see annotated figure below) extending from the casing (see annotated figures below) and into the bleed air cavity 62, wherein the bleed flow extension (see annotated figure below) is a circumferential structure (the diffuser channel is annular and thus the bleed flow extension extend into the page circumferentially for example) extending from an edge of the casing (see annotated figure below) that defines a forward edge (see annotated figure below) of the bleed aperture (see annotated figure below), the bleed flow extension being an extension of the material of the casing (see fig. 10 showing the material of bleed flow extension is a the same as the material of the casing) and having a material thickness (see thickness of bleed flow extension in fig. 10), a material thickness of the casing (see material thickness of casing in fig. 10), and comprises a linear portion (portion labeled "bleed flow extension" in annotated figure below) that extends (see annotated figure below) from the casing and into (see annotated figure below) the bleed air cavity,
wherein a diffuser (see par. 48, top) channel (annular channel 470) is defined between an upstream wall (see annotated figure below) and a downstream wall (see annotated figure below), wherein the upstream wall of the diffuser channel is defined by a surface (surface at location of pointer) of the bleed flow extension (see annotated figure below) and the downstream wall (see annotated figure below) of the diffuser channel defined by a surface (see annotated figure below) of the impeller shroud (58 shown in fig. 1 and see annotated figure below) opposite a surface (see annotated figure below) of the impeller shroud that defines a portion of the core flow path,
wherein the diffuser channel 470 has an inlet 480 area that is less than (see par. 48) an outlet 482 area,
wherein the combustor portion (portion of core flow F entering impeller 46 blades 54 in fig. 1) of the core flow F received at the inlet (see annotated figure below) to the impeller 46 is compressed (by impeller blades 54, see par. 31, bottom) and turned from an axial flow direction (see annotated figure below) to a radial flow direction (upward along impeller blades 54 in fig. 1, see par. 27, middle) and then directed into the combustor 16 and wherein a bleed air portion (portion entering bleed aperture and going through diffuser channel 470; see annotated figure below) of the core flow F received at the inlet (see annotated figure below) to the impeller 46 is separated from the combustor portion (portion of core flow F entering impeller 46 blades 54 in fig. 1) at the bleed aperture (see annotated figure below) and directed through the diffuser channel 470 and into the bleed air cavity 62.
Donnelly does not disclose one or more supports arranged within the circumferential slot and structurally connecting the casing with the impeller shroud; the material thickness of the bleed flow extension equal to the material thickness of the casing (i.e., the proportion of the bleed flow extension material thickness to the casing material thickness is equal to one); and a curved portion (of the bleed flow extension) that extends from the linear portion into the bleed air cavity.
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[AltContent: textbox (engine housing)][AltContent: arrow][AltContent: textbox (inlet to impeller 46 identified in fig. 1)][AltContent: textbox (impeller 46)][AltContent: arrow][AltContent: textbox (impeller shroud 58 (see fig. 1))][AltContent: arrow][AltContent: textbox (bleed flow extension; upstream wall)][AltContent: arrow][AltContent: textbox (surface of impeller shroud; downstream wall)][AltContent: arrow][AltContent: textbox (axial flow direction)][AltContent: arrow][AltContent: textbox (bleed aperture)][AltContent: arrow][AltContent: textbox (fillet)][AltContent: arrow][AltContent: textbox (inlet to diffuser channel 470)][AltContent: arrow][AltContent: textbox (casing)][AltContent: arrow][AltContent: textbox (edge of casing; forward edge)][AltContent: arrow][AltContent: arrow][AltContent: textbox (surface of the impeller shroud that defines a portion of the core flow path)][AltContent: arrow]
Hampton teaches (see figs. 1-3) a gas turbine (see fig. 1) and further teaches one or more supports 42 (i.e., ribs 42) structurally connecting a casing (at 30 in fig. 2) with an impeller (see impeller at location of the text “43” in fig. 2) shroud (at 43 in fig. 2).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to provide Donnelly with the one or more supports structurally connecting the casing with the impeller shroud as taught by Hampton to provide structural support across the annular diffuser channel 470 of Donnelly (see Hampton col. 2, ll. 20-25). This results in the upstream end of one or more supports 164 (see Hampton fig. 2) being structurally connected to the casing (see Donnelly annotated figures above) of the compressor 24 (see Donnelly fig. 1) and the downstream end of the one or more supports 164 (see Hampton fig. 2) being structurally connected to the impeller shroud 58 (see Donnelly annotated figures above). A bleed aperture of Donnelly in view of Hampton would be defined circumferentially between the one or more supports because the annular diffuser channel 470 (see Donnelly fig. 10) of Donnelly in view of Hampton would be separated into for example two or more diffuser channels by way of the one or more support taught by Hampton.
Tawfik teaches a gas turbine 12 (see fig. 1) and further teaches (see annotated figure 5 below) a curved portion (see annotated figure below) (curved portion of diffuser channel 166 in combination with a throat section 164) that extends from a linear portion (see annotated figure below; such linear portion corresponding with throat section 164). Tawfik teaches a diffuser channel 166 (in combination with the throat section 164 extending from a casing (see annotated figure below) to a bleed air plenum 42 that have a bleed angle (see annotated figure below) less than 90° (i.e., “low offtake angle” at par. 42, bottom) and have a curved portion result in low or zero swirling exit flow (see par. 42, bottom) thereby preserving pressure recovery (see par. 5). It is further noted that “when a patent claims a structure already known in the prior art that is altered by the mere substitution of one element for another known in the field, the combination must do more than yield a predictable result.” KSR International Co. v. Teleflex Inc., 82 USPQ2d 1385 at 1395 (U.S. 2007) (MPEP 2143 I.B.).
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It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to substitute the type bleed structure Tawfik (i.e. a diffuser channel with a curved portion that extends from the linear throat portion and also a low bleed angle) for the type of bleed structure of Donnelly in view of Hampton (diffuser channel without linear throat section) for the purpose of substituting one known element for another in order to provide the expected result of providing a pathway to extract bleed air from a gas turbine compressor to a bleed cavity of the combination and for the purpose of facilitating reduced swirling (see par. 42) and thereby preserving pressure recovery and also to facilitate static pressure increase (“the bleed port flowpath is shaped to cause a static pressure increase in the air flowing therein”; see par. 5) in order to overcome prior art deficiencies caused by “limited shape variation”; see par. 6) (Tawfik’s instant teachings also reduce flow separation as discussed in par. 41). Thus having a linear/curved shape variation is beneficial to reducing pressure losses and thus mitigates the need to mechanically increase pressure of bled air with pumps for example. This results in the bleed air extension of Donnelly in view of Hampton and Tawfik having a curved portion that extends from the linear portion into the bleed air cavity. This is evidenced by Cummings fig. 2 showing a curved portion of a bleed air extension extending into a bleed air cavity 58. In other words Cummings is evidence that a person of ordinary skill in the art could configure the combination as stated above regarding bleed air extension of Donnelly in view of Hampton and Tawfik having a curved portion that extends from the linear portion into the bleed air cavity.
Regarding the claim 1 feature the proportion of the bleed flow extension material thickness to the casing material thickness is equal to one In Gardner v. TEC Syst., Inc., 725 F.2d 1338, 220 USPQ 777 (Fed. Cir. 1984), cert. denied, 469 U.S. 830, 225 USPQ 232 (1984), the Federal Circuit held that, where the only difference between the prior art and the claims was a recitation of relative dimensions of the claimed device and a device having the claimed relative dimensions would not perform differently than the prior art device, the claimed device was not patentably distinct from the prior art device.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention that the Donnelly in view of Hampton and Tawfik proportion of the bleed flow extension material thickness to the casing material thickness would have performed similar to the claimed the proportion of the bleed flow extension material thickness to the casing material thickness is equal to one and thus such feature is not patentably distinct.
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Regarding claim 3, The combination of Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. The combination teaches the linear portion (portion labeled “bleed flow extension” in Donnelly annotated figure above and see also linear portion in Tawfik annotated figure above) extends at a bleed angle (a low bleed angle as shown in Tawfik annotated figure above) relative to the casing (see casing in Donnelly annotated figures above).
Regarding claim 5, Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. Donnelly further discloses a fillet (see Donnelly annotated figure above) at a location where the linear portion (portion labeled “bleed flow extension” in Donnelly annotated figure above) extends from the casing (see annotated figures above) and defining a portion of an inlet (see annotated figure above) to the diffuser channel 470. It is noted that the angle of the fillet of the combination Donnelly in view of Hampton and Tawfik resembles the fillet shown in Tawfik annotated figure above because of the low bleed angle teaching of Tawfik in the claim 1 analysis above.
Regarding claim 6, The combination of Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. Donnelly further discloses a distance (R1) (see annotated figures above) of the casing (see annotated figures above) from the engine axis A. The combination teaches the linear portion has a length (L1) (see Tawfik annotated figure above) defined relative to a distance (R1) (see annotated figures above) of the casing from the engine axis. Donnelly does not disclose 0.05R1 ≤ L1 ≤ 0.25R1 (i.e., 0.05 ≤ (L1/R1) ≤ 0.25). It is further noted that “where the only difference between the prior art and the claims was a recitation of relative dimensions of the claimed device and a device having the claimed relative dimensions would not perform differently than the prior art device, the claimed device was not patentably distinct from the prior art device”. In Gardner v. TEC Syst., Inc., 725 F.2d 1338, 220 USPQ 777 (Fed. Cir. 1984), cert. denied, 469 U.S. 830, 225 USPQ 232 (1984) (MPEP 2144.04 IV. A.).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention that the linear portion with L1/R1 of the combination would have performed similar to the claimed linear portion with 0.05 ≤ (L1/R1) ≤ 0.25 and thus the claimed linear portion is not patentably distinct.
Regarding claim 7, The combination of Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. Reference(s) of the combination teach the curved portion (see Tawfik annotated figure above) has an arc length (L2) (see annotated figure above) and an arc radius (R2) (see annotated figure above) relative to a distance (R1) (see Donnelly annotated figure above) of the casing (see annotated figures above) from the engine axis A. Donnelly does not explicitly disclose L2 and R2 defined relative to R1: 0.25R1 ≤ L2 ≤ 0.50R1 (i.e., 0.25 ≤ (L2/R1) ≤ 0.5) and 0.05R1 ≤ R2 ≤ 0.40R1 (i.e., 0.05 ≤ (R2/R1) ≤ 0.40). It is further noted that “where the only difference between the prior art and the claims was a recitation of relative dimensions of the claimed device and a device having the claimed relative dimensions would not perform differently than the prior art device, the claimed device was not patentably distinct from the prior art device”. In Gardner v. TEC Syst., Inc., 725 F.2d 1338, 220 USPQ 777 (Fed. Cir. 1984), cert. denied, 469 U.S. 830, 225 USPQ 232 (1984) (MPEP 2144.04 IV. A.).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention that the curved portion with L2/R1 and R2/R1 of the combination would have performed similar to the claimed curved portion with 0.25 ≤ (L2/R1) ≤ 0.5 and 0.05 ≤ (R2/R1) ≤ 0.40 and thus the claimed curved portion is not patentably distinct.
Regarding claim 9, Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. Donnelly further discloses the bleed flow extension (see annotated figure above) comprises the linear portion (annotated portion labeled “bleed flow extension) extending at least partially radially outward from the casing (see annotated figure above). The teachings of Hampton applied in the claim 1 analysis above include wherein the one or more supports 42 extend between the impeller (see impeller at location of the text “43” in fig. 2) shroud (at 43 in fig. 2) and a portion of a bleed flow extension (see annotated figure below). This results in the Donnelly in view of Hampton and Tawfik one or more supports extending between the impeller shroud and the linear portion because the support taught by Hampton begins at the Hampton entrance or bleed aperture (i.e. at fig. 2 arrow pointer at entrance of diffuser channel 41).
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Regarding claim 14, Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. The teachings of Hampton applied in the claim 1 analysis above include at least one stiffener element 42 (Hampton teaches a plurality of ribs 42 at col. 2, ll. 20-25; thus the ribs can serve as a claim 1 “support” and claim 14 “stiffener element”) arranged within a diffuser channel 41 and extending between a surface of a bleed flow extension (see annotated figure above) and a surface of the impeller (see impeller at location of the text “43” in fig. 2) shroud (at 43 in fig. 2).
Regarding claim 15, Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. The teachings of Hampton applied in the claim 1 analysis above include wherein the at least one stiffener element 42 is arranged radially (see two interpretations in annotate figure above) relative to an engine axis (at location 20 in fig. 1).
Regarding claim 18, Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. Donnelly discloses (see fig. 1) the bleed air cavity 62 is fluidly coupled to at least one of an engine system and an aircraft system 66 and configured to supply bleed air to the respective system (see par. 33, top).
Regarding claim 19, Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. Donnelly discloses (see fig. 1) wherein the compressor section 24 comprises at least one rotor element 32 and at least one vane element 34.
Regarding claim 20, Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. Donnelly discloses (see fig. 1) wherein the at least one vane 34 element is arranged axially aft of the at least one rotor element 32, and the bleed aperture (see annotated figures above) is positioned axially aft of the at least one vane element 34.
Claim(s) 4 is/are rejected under 35 U.S.C. 103 as being unpatentable over Donnelly in view of Hampton and Tawfik as applied to claim 3 above, and further in view of Pub. No.: US 2004/0191058 A1 (Baumann).
Regarding claim 4, Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. Donnelly does not disclose wherein the bleed angle is equal to or greater than 30° and less than or equal to 60°.
Baumann teaches (see figs. 1 and 2) a gas turbine 100 and further teaches a bleed angle (see annotated figure below) is equal to or greater than 30° and less than or equal to 60° (one of ordinary skill would understand the annotated bleed angle below to be equivalent to the angle θ in fig. 1A of Baumann wherein θ can be 40°to 50°; see par. 22, top).
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It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to provide Donnelly in view of Hampton and Tawfik with the bleed angle is equal to or greater than 30° and less than or equal to 60° as taught by Bauman in order to facilitate minimizing flow disturbances and pressure losses (see Baumann par. 22, bottom) and reducing stall tendencies (see Baumann par. 6, bottom).
Claim(s) 11 is/are rejected under 35 U.S.C. 103 as being unpatentable over Donnelly in view of Hampton and Tawfik as applied to claim 1 above, and further in view of US 2025/0059920 A1 (Wulff), US 20220282627 A1 (Wickersham) and NPL Gas Turbine Combustion, Alternative Fuels and Emissions (Lefebvre).
Regarding claim 11, Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above including that the inlet area is less than the outlet area as discussed in the claim 1 analysis above. Donnelly does not explicitly teach the inlet area is 4 times or less than that of the outlet area. In other words Donnelly does not disclose the outlet area (AO) is greater than or equal to four times the inlet area (AI), still in other words AO/AI ≥ 4.
The presence of a known result-effective variable would be a motivation for a person of ordinary skill in the art to experiment to reach another workable product or process. See KSR; MPEP 2144.05(II)(B). A particular parameter is a result-effective variable when the variable is known to achieve a recognized result. See In re Antonie, 559 F.2d 618, 620, 195 USPQ 6,8 (CCPA 1977).
Here, Wulff teaches in paragraph 32 that the flow area of a diffusion flow passage has an increasing flow area in order to reduce the velocity and increase the static pressure of the bleed air flowing through the diffuser passage in the downstream direction, in order to provide aircraft systems with bleed air at appropriate pressures (see par. 57, bottom) via a bleed air plenum with appropriate static pressure, see par. 26, bottom, such as bleed air plenum 64 in Wulff fig. 1. Wickersham points out in par. 19 that diffuser area ratio is varied along with diffuser length in order to optimize performance. For example, if the area of the diffuser is expanded too rapidly, in order to minimize diffuser length to reduce weight, then flow separation occurs resulting in diffuser losses. That the area ratio of a diffuser is a major parameter used to determine the performance of a diffuser is confirmed by Lefebvre that points out that area ratio is used to calculate the rise is static pressure of the air traveling through the diffuser (see page 81 and equation 3.9 on page 84 that includes the area ratio AR when calculating the rise in static pressure). Lefebvre further discusses that the diffuser area ratio is the area A1 at the inlet of diffuser divided by the area A2 at the outlet of the diffuser (see fig. 3.4 and equation 3.7). The calculated rise in static pressure, p2 – p1, is used to derive several useful parameters for expressing diffuser performance (see page 84, middle, and see parameters in equations (3.10), (3.11) and (3.12)). Therefore, an ordinary skilled worker would recognize that the area ratio AO/AI is a result-effective variable that controls the static pressure of bleed air, in conjunction with the length of a diffuser passage, supplied to aircraft systems. Thus, the claimed AO/AI ≥ 4 is found to be an obvious optimization of the prior art obtainable by an ordinary skilled worker through routine experimentation.
Therefore, since the general conditions of the claim, i.e. AO/ AI > 1, were taught in the prior art by Donnelly in view of Hampton and Tawfik, it is not inventive to discover the optimum workable range by routine experimentation, and it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Donnelly in view of Hampton and Tawfik’s invention to include wherein AO/ AI ≥ 4 in order to provide an optimum static pressure for aircraft systems as suggested and taught by Wulff, Wickersham and Lefebvre. It has been held “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation”, In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955).
Claim(s) 12 is/are rejected under 35 U.S.C. 103 as being unpatentable over Donnelly in view of Hampton and Tawfik as applied to claim 1 above, and further in view of NPL Lefebvre and NPL “Experimental and computational study of performance characteristics in S-shaped diffuser” (Gupta).
Regarding claim 12, Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. Donnelly further discloses a coefficient of pressure (Cp) along an upstream wall (wall labeled “bleed flow extension” in annotated figure above) of the diffuser channel 470 and a coefficient of pressure (Cp) along a downstream wall (wall labeled “surface of impeller shroud” in annotated figure above) of the diffuser channel 470. As explained below, the Cp is a fundamental property of diffusers and represents how efficiently a diffuser increases static pressure of the air flowing through the diffuser. Donnelly does not expressly teach the claimed wherein the Cp long the upstream wall of the diffuser channel and the Cp along he downstream wall are each less than 0.6.
The presence of a known result-effective variable would be a motivation for a person of ordinary skill in the art to experiment to reach another workable product or process. See KSR; MPEP 2144.05(II)(B). A particular parameter is a result-effective variable when the variable is known to achieve a recognized result. See In re Antonie, 559 F.2d 618, 620, 195 USPQ 6,8 (CCPA 1977).
Here, Lefebvre teaches on page 84 that the coefficient of pressure (Cp) was a standard variable calculated for diffusers. The function of a diffuser is to reduce velocity and to convert kinetic energy or dynamic pressure into a rise in static pressure (see page 83, middle). Such rise in static pressure, p2 – p1, is used to derive several useful parameters for expressing diffuser performance (see page 84, middle and parameters in equations (3.10), (3.11) and (3.12), wherein equation (3.10) represents coefficient of pressure Cp). One of ordinary skill would understand the Cp to represent the static pressure increase along each of the diverging walls shown in fig. 3.4, such walls corresponding with the claimed upstream and downstream walls and those disclosed by Donnelly. Lefebvre further points out that from a design standpoint, an ideal diffuser achieves the velocity reduction and pressure increase in the shortest possible length (see page 80, top). Gupta teaches a curved diffuser (see fig. 2) related to gas turbine diffusers (see endnote [11] at end of document) and further teaches in fig. 9 that Cp generally scales with the length of the diffuser. Therefore, at certain higher coefficients of pressure, a high diffuser length would be prohibitive because of the increased weight and space consumption of the diffuser that should be minimized on an aircraft gas turbine engine.
Therefore, an ordinary skilled worker would recognize that the overall coefficient of pressure (Cp) of a diffuser is a result-effective variable that is used to control a length of the diffuser . Thus, the claimed wherein the Cp along the upstream wall of the diffuser channel and the Cp along the downstream wall are each less than 0.6. is found to be an obvious optimization of the prior art obtainable by an ordinary skilled worker through routine experimentation.
Therefore, since the general conditions of the claim, i.e. a coefficient of pressure (Cp) along an upstream wall (wall labeled “bleed flow extension” in annotated figure above) of the diffuser channel 470 and a coefficient of pressure (Cp) along a downstream wall (wall labeled “surface of impeller shroud” in annotated figure above) of the diffuser channel 470, were taught in the prior art by Donnelly in view of Hampton and Tawfik teach, it is not inventive to discover the optimum workable range by routine experimentation, and it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Donnelly in view of Hampton and Tawfik’s invention to include wherein the Cp along the upstream wall of the diffuser channel and the Cp along the downstream wall are each less than 0.6 in order to an optimal diffuser length as suggested and taught by Lefebvre and Gupta above. It has been held “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation”, In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955).
It is repeated from above that Lefebvre teaches that the coefficient of pressure (Cp) is a standard variable calculated for diffusers and Gupta specifically teaches in fig. 9 values of Cp less than 0.6. It is further noted that “when a patent claims a structure already known in the prior art that is altered by the mere substitution of one element for another known in the field, the combination must do more than yield a predictable result.” KSR International Co. v. Teleflex Inc., 82 USPQ2d 1385 at 1395 (U.S. 2007) (MPEP 2143 I.B.).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to substitute the Cp less than 0.6 taught by Lefebvre and Gupta for each of the Cp along the upstream wall of the diffuser channel and the Cp along the downstream wall of the diffuser channel for those of Donnelly in view of Hampton and Tawfik for the purpose of substituting one known element for another in order to provide the expected result of a measure of the increase in static pressure of the diffuser channel of the combination.
Claim(s) 16 and 17 is/are rejected under 35 U.S.C. 103 as being unpatentable over Donnelly in view of Hampton and Tawfik as applied to claim 1 above, and further in view of (Pub. No.: US 2025/0059920 A1) Wulff .
Regarding claim 16, Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. Donnelly does not explicitly disclose the at least one stiffener element is arranged with a circumferential angled orientation relative to the engine axis.
Wulff teaches (see figs. 6-7) the at least one stiffener element 164 is arranged with a circumferential angled orientation (see fig. 7 for example showing the stiffener element 164 being canted with respect to the dashed radial lines; one of ordinary skill when viewing fig. 6 would understand such radial lines to extend from the engine axis 12) relative to the engine axis (12 in fig. 6 and 212 in fig. 9).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to provide Donnelly with the at least one stiffener element of Donnelly in view of Hampton and Tawfik is arranged with a circumferential angled orientation relative to the engine axis as taught by Wulff in order to facilitate reducing metal fatigue and vibrations (see Wulff par. 21, bottom). Wulff teaches using circumferential angled orientation stiffeners with varied angular spacing between bleed channels reduces vibration noise (see varied spacings 172,174 in fig. 6).
Regarding claim 17, Donnelly in view of Hampton and Tawfik teach the current invention as claimed and discussed above. Donnelly does not explicitly teach wherein the at least one stiffener has an airfoil configuration.
Wulff teaches (see figs. 6-7) the at least one stiffener 164 has an airfoil configuration (see figs. 6-7 wherein the stiffener elements 164 look like the leading edge of a wing or airfoil).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to provide Donnelly in view of Hampton and Tawfik with wherein the at least one stiffener has an airfoil configuration as taught by Wulff in order to facilitate reducing metal fatigue and vibrations (see Wulff par. 21, bottom). Wulff teaches using airfoil configuration stiffeners with varied angular spacing between bleed channels reduces vibration noise (see varied spacings 172,174 in fig. 6).
Response to Arguments
Applicant's arguments filed 01/20/2026 have been fully considered but they are not persuasive. Applicant argues that the cited prior art do not teach or suggest the claimed bleed flow extension having a linear portion and a curved portion that extend into the bleed air cavity. It is noted that Tawfik (Pub. No.: US 2019/0226488 A1) fig. 5 teaches an annular (see par. 44: “the bleed port 150 is configured as a slot extending … wholly around the central longitudinal axis 13 (FIG. 1) and bounded by forward and aft sidewalls 160. The bleed port 150 may be described as … annular”) diffuser channel 150 with a linear portion (see annotated figure below) and a curved portion (see annotated figure below). This is beneficial because the “variation of shape” (see Tawfik par. 5) between linear and curved improves pressure losses when bleed air is extracted from the compressor flowpath. In addition the Tawfik low bleed angle (see annotated figure below) results in reduction of swirl that removes energy from the bleed flow (and thus may also decrease pressure recovery) and also is used to avoid mechanical obstructions (see par. 42).
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[AltContent: textbox (liner portion)][AltContent: textbox (curved portion)][AltContent: arrow][AltContent: arrow][AltContent: arc][AltContent: textbox (low bleed angle)][AltContent: textbox (fillet)][AltContent: arrow][AltContent: textbox (L1)][AltContent: arrow][AltContent: oval][AltContent: oval][AltContent: textbox (arc length L2 (length between shaded dots))][AltContent: arrow][AltContent: arrow][AltContent: textbox (R2)][AltContent: arrow][AltContent: textbox (casing)][AltContent: arrow][AltContent: arrow]
Tawfik applied to Donnely (Pub. No.: US 2018/0355877 A1) in view of Hampton (US Patent 3,632,223) in the claim 1 analysis in the 103 section above results in the bleed extension having a curved portion extending into the bleed air cavity because of the instant Tawfik teaching (this is evidenced by Cummings (Pub. No.: US 2005/0106009 A1) fig. 2 as shown in the 103 section above). Applicant argues against Tawfik fig. 7. In response the non-final office action cited both fig. 5 and fig. 7 in support of the instant linear and curved portions. However fig. 7 is no longer supported in this office action and thus such arguments are moot. Applicant further argues against Tawfik fig. 5-6 vanes 168. It is noted that such vanes 168 are optional (see par. 46: The bleed port 150 may include plurality of vanes … In the case where such vanes 168 are not present …”). However such vanes are similar to (vanes 168 extend fully from upstream wall to downstream wall; see Tawfik par. 46) supports and thus Tawfik is consistent with the Hampton one or more supports applied in the claim 1 analysis above such Hampton supports used because Hampton includes the one or more supports arranged structurally connecting a casing with an impeller shroud as claimed. Applicant further argues Tawfik fails to provide teaching of the claimed bleed aperture, bleed flow extension, and diffuser channel. In response Donnelly discloses the claimed bleed aperture (see annotated figure below), bleed flow extension (see annotated figure below), and diffuser (see par. 48, top) channel (annular channel 470). Tawfik is merely used to teach introducing a curved portion to the Donnelly bleed flow extension. One of ordinary skill in the art would naturally be motivated to include the benefits of a low bleed angle also.
Applicant discusses the material of the bleed flow extension is a continuation of the material of the casing. Such is disclosed by Donnelly in fig. 10 above. The thickness limitation was addressed by In Gardner v. TEC Syst., Inc., 725 F.2d 1338, 220 USPQ 777 (Fed. Cir. 1984), cert. denied, 469 U.S. 830, 225 USPQ 232 (1984) in the 103 section above. Applicant does not appear to have a particular reason for this thickness feature. For example par. 54 states “Although specific example relationships, values, and characteristics are described herein, those of skill in the art will appreciate that the … thicknesses … may be selected outside of the disclosed values/ranges”.
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[AltContent: textbox (engine housing)][AltContent: arrow][AltContent: textbox (inlet to impeller 46 identified in fig. 1)][AltContent: textbox (impeller 46)][AltContent: arrow][AltContent: textbox (impeller shroud 58 (see fig. 1))][AltContent: arrow][AltContent: textbox (bleed flow extension; upstream wall)][AltContent: arrow][AltContent: textbox (surface of impeller shroud; downstream wall)][AltContent: arrow][AltContent: textbox (axial flow direction)][AltContent: arrow][AltContent: textbox (bleed aperture)][AltContent: arrow][AltContent: textbox (fillet)][AltContent: arrow][AltContent: textbox (inlet to diffuser channel 470)][AltContent: arrow][AltContent: textbox (casing)][AltContent: arrow][AltContent: textbox (edge of casing; forward edge)][AltContent: arrow][AltContent: arrow][AltContent: textbox (surface of the impeller shroud that defines a portion of the core flow path)][AltContent: arrow]
Pertinent Prior Art
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure:
Airfoil shaped stiffener: US 10934943 (figs.2-3)
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to MARC J AMAR whose telephone number is (571)272-9948. The examiner can normally be reached M-F 9:00-6:00.
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/MARC AMAR/Examiner, Art Unit 3741 /DEVON C KRAMER/Supervisory Patent Examiner, Art Unit 3741
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