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 .
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 11 December 2025 has been entered.
Response to Arguments
Applicant’s arguments, see Remarks, filed 11 December 2025, with respect to the rejection(s) of claim(s) 1-3, 5-18 and 5-18 20-21 under 35 USC 103 have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of Savela (US 20140060083 A1; also US 9,476,320 B2), Moore et al (US 20200200089 A1; also US 11,988,148 B2) and/or Walker (US 20200056543 A1).
Applicant’s arguments, see Remarks, filed 11 December 2025, with respect to new claims 22-23 have been fully considered and are partially persuasive. Note that newly presented claim 22 has an effective filing date of 20 June 2024 and there is prior art that render the claim obvious, see rejection below. Newly presented claim 23 has an effective filing date of 19 December 2019 and is being indicated herein as allowable.
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) 1-3 and 5 (examined as effectively filed on 20 June 2024) is/are rejected under 35 U.S.C. 103 as being unpatentable over Savela (US 20140060083 A1; also US 9,476,320 B2) in view of Moore et al – hereafter Moore – (US 20200200089 A1; also US 11,988,148 B2).
Regarding claim 1, Savela teaches a gas turbine engine for an aircraft (Fig.1-3) comprising:
an engine core (Fig.2) comprising:
a turbine that is a lowest pressure turbine (46) of the gas turbine engine, the turbine having a turbine length defined as a distance between a root of a most upstream blade of the turbine at a leading edge thereof and a root of a most downstream blade of the turbine at a trailing edge thereof (Fig.3),
a compressor (44) that is a lowest pressure compressor of the gas turbine engine (Fig.2),
a core shaft (30) connecting the turbine to the compressor, and
three bearings (38C/D/E) arranged to support the core shaft, the three bearings comprising a forward bearing (38C) and two rearward bearings (38D/E), with a minor span, S, being defined as an axial distance between the two rearward bearings (90);
a fan (22) located upstream of the engine core (Fig.2), the fan comprising a plurality of fan blades (inherent property of a gas turbine engine fan); and
a gearbox (48) configured to receive an input from the core shaft and output drive to the fan so as to drive the fan at a lower rotational speed than the core shaft (¶34),
wherein:
the core shaft has a length, L, between the forward bearing and a rearmost bearing of the two rearward bearings (Fig.2).
However, Savela does not explicitly teach the core shaft has a speed at maximum take-off (MTO) within a range of 5000 rpm to 8000 rpm, and a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio of:
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is in a range of 0.05 to 0.2.
However, it is noted that applicant has not disclosed that having the ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being in a range of 0.05 to 0.2 results in an unpredicted result not seen in the prior art and it appears that the invention of Savela would perform equally well with a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being in a range of 0.05 to 0.2. Accordingly, it has been 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 (MPEP 2144.04(IV)(A)).
Moore teaches a low noise gas turbine engine with a core shaft having a speed at maximum take-off (MTO) within a range of 5000 rpm to 8000 rpm (¶53 last sentence; ¶54). Said configuration results in a gas turbine engine with acceptably low noise levels (¶53).
It would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to modify the gas turbine engine of Savela by having the core shaft has a speed at maximum take-off (MTO) within a range of 5000 rpm to 8000 rpm based on the teachings of Moore because this would provide a gas turbine engine configuration producing reasonably low noise levels.
Regarding claim 2, Savela and Moore teach all the limitations of claim 1, see above, however, do not explicitly teach the ratio of the minor span to core shaft length ratio to the minor span to turbine length ratio is less than 0.175 or less than 0.15.
However, it is noted that applicant has not disclosed that having the ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being less than 0.175 or less than 0.15 results in an unpredicted result not seen in the prior art and it appears that the invention of Savela and Moore would perform equally well with a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being less than 0.175 or less than 0.15. Accordingly, it has been 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 (MPEP 2144.04(IV)(A)).
Regarding claim 3, Savela and Moore teach all the limitations of claim 2, see above, however, do not explicitly teach the ratio of the minor span to core shaft length ratio to the minor span to turbine length ratio is greater than 0.075, greater than 0.08, or greater than 0.09.
However, it is noted that applicant has not disclosed that having the ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being greater than 0.075, greater than 0.08, or greater than 0.09 results in an unpredicted result not seen in the prior art and it appears that the invention of Savela and Moore would perform equally well with a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being greater than 0.075, greater than 0.08, or greater than 0.09. Accordingly, it has been 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 (MPEP 2144.04(IV)(A)).
Regarding claim 5, Savela and Moore teach all the limitations of claim 1, see above, however, do not explicitly teach the ratio of the minor span to core shaft length ratio to the minor span to turbine length ratio is less than 0.12 and greater than 0.07.
However, it is noted that applicant has not disclosed that having the ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being in a range of 0.05 to 0.2 results in an unpredicted result not seen in the prior art and it appears that the invention of Savela and Moore would perform equally well with a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being in a range of 0.05 to 0.2. Accordingly, it has been 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 (MPEP 2144.04(IV)(A)).
Claim(s) 6-18 and 20-21 (examined as effectively filed on 20 June 2024) is/are rejected under 35 U.S.C. 103 as being unpatentable over Savela and Moore as applied to claim 1 above, and further in view of Walker (US 20200056543 A1).
Regarding claim 6, Savela and Moore teach all the limitations of claim 1, see above, however, do not explicitly teach the ratio of the minor span to core shaft length ratio to the minor span to turbine length ratio is greater 0.12 and the fan has a fan tip loading at cruise conditions greater than 0.30.
However, it is noted that applicant has not disclosed that having the ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being greater than 0.12 results in an unpredicted result not seen in the prior art and it appears that the invention of Savela and Moore would perform equally well with a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being greater than 0.12. Accordingly, it has been 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 (MPEP 2144.04(IV)(A)).
Walker teaches a gas turbine engine (Fig.1) including a fan (23), a gear (30), a low pressure compressor (14), a low pressure turbine (19) and a core shaft (26) connecting the low pressure compressor and turbine. Walker further teaches the fan has a fan tip loading at cruise conditions greater than 0.30 (¶24).
It would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to further modify the gas turbine engine of Savela and Moore by the fan having a fan tip loading at cruise conditions greater than 0.30 based on the teachings of Walker because this would require a simple substitution of one known element (fan tip loading at cruise of Savela and Moore) for another (fan tip loading at cruise of Walker) to obtain a predictable results (operating a gas turbine engine to produce thrust to power an aircraft).
Regarding claim 7, Savela, Moore and Walker further teach the fan tip loading at cruise conditions is greater than 0.31 and less than 0.4 (Walker ¶24).
Regarding claim 8, Savela and Moore teach all the limitations of claim 1, see above, however, do not explicitly teach the ratio of the minor span to core shaft length ratio to the minor span to turbine length ratio is in the range of from 0.12 to 0.14 and a bypass ratio at cruise conditions is in a range of from 10 to 12.
However, it is noted that applicant has not disclosed that having the ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being in the range of from 0.12 to 0.14 results in an unpredicted result not seen in the prior art and it appears that the invention of Savela and Moore would perform equally well with a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being in the range of from 0.12 to 0.14. Accordingly, it has been 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 (MPEP 2144.04(IV)(A)).
Walker teaches a gas turbine engine (Fig.1) including a fan (23), a gear (30), a low pressure compressor (14), a low pressure turbine (19) and a core shaft (26) connecting the low pressure compressor and turbine. Walker further teaches a bypass ratio at cruise conditions is in a range of from 10 to 12 (¶25).
It would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to further modify the gas turbine engine of Savela and Moore by having a bypass ratio at cruise conditions is in a range of from 10 to 12 based on the teachings of Walker because this would require a simple substitution of one known element (bypass ratio at cruise of Savela and Moore) for another (bypass ratio at cruise of Walker) to obtain a predictable results (operating a gas turbine engine to produce thrust to power an aircraft).
Regarding claim 9, Savela, Moore and Walker further teach the fan has a fan tip loading at cruise conditions greater than 0.30 (Walker ¶24).
Regarding claim 10, Savela and Moore teach all the limitations of claim 1, see above, however, do not explicitly teach the ratio of the minor span to core shaft length ratio to the minor span to turbine length ratio is less than 0.14 and the fan has a fan tip loading at cruise conditions greater than 0.29.
However, it is noted that applicant has not disclosed that having the ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being less than 0.14 results in an unpredicted result not seen in the prior art and it appears that the invention of Savela and Moore would perform equally well with a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being less than 0.14. Accordingly, it has been 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 (MPEP 2144.04(IV)(A)).
Walker teaches a gas turbine engine (Fig.1) including a fan (23), a gear (30), a low pressure compressor (14), a low pressure turbine (19) and a core shaft (26) connecting the low pressure compressor and turbine. Walker further teaches the fan has a fan tip loading at cruise conditions greater than 0.29 (¶24).
It would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to further modify the gas turbine engine of Savela and Moore by the fan having a fan tip loading at cruise conditions greater than 0.29 based on the teachings of Walker because this would require a simple substitution of one known element (fan tip loading at cruise of Savela and Moore) for another (fan tip loading at cruise of Walker) to obtain a predictable results (operating a gas turbine engine to produce thrust to power an aircraft).
Regarding claim 11, Savela, Moore and Walker further teach the fan tip loading at cruise conditions is greater than 0.30 or greater than 0.31 (Walker ¶24).
Regarding claim 12, Savela and Moore teach all the limitations of claim 1, see above, however, do not explicitly teach the ratio of the minor span to core shaft length ratio to the minor span to turbine length ratio is greater than 0.09 and the fan has a fan diameter greater than 220 cm.
However, it is noted that applicant has not disclosed that having the ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being greater than 0.09 results in an unpredicted result not seen in the prior art and it appears that the invention of Savela and Moore would perform equally well with a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being greater than 0.09. Accordingly, it has been 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 (MPEP 2144.04(IV)(A)).
Walker teaches a gas turbine engine (Fig.1) including a fan (23), a gear (30), a low pressure compressor (14), a low pressure turbine (19) and a core shaft (26) connecting the low pressure compressor and turbine. Walker further teaches the fan has a fan diameter greater than 220 cm (¶22).
It would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to further modify the gas turbine engine of Savela by the fan having a fan diameter greater than 220 cm based on the teachings of Walker and Moore because this would require a simple substitution of one known element (fan diameter of Savela and Moore) for another (fan diameter of Walker) to obtain a predictable results (operating a gas turbine engine to produce thrust to power an aircraft).
Regarding claim 13, Savela, Moore and Walker further teach the fan diameter is less than 420 cm (Walker ¶22).
Regarding claim 14, Savela and Moore teach all the limitations of claim 1, see above, and further teach the core shaft has a running speed range from 1500 rpm to 6200 rpm (Moore ¶54), however, do not explicitly teach a bypass ratio at cruise conditions is greater than 12.5.
Walker teaches a gas turbine engine (Fig.1) including a fan (23), a gear (30), a low pressure compressor (14), a low pressure turbine (19) and a core shaft (26) connecting the low pressure compressor and turbine. Walker further teaches a bypass ratio at cruise conditions is greater than 12.5 (¶25).
It would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to further modify the gas turbine engine of Savela and Moore by having a bypass ratio at cruise conditions is greater than 12.5 based on the teachings of Walker because this would require a simple substitution of one known element (bypass ratio at cruise of Savela and Moore) for another (bypass ratio at cruise of Walker) to obtain a predictable results (operating a gas turbine engine to produce thrust to power an aircraft).
Regarding claim 15, Savela and Moore teach all the limitations of claim 1, see above, however, do not explicitly teach the ratio of the minor span to core shaft length ratio to the minor span to turbine length ratio is in the range of from 0.13 to 0.14, the fan blades have a hub-to-tip ratio in a range of from 0.28 to 0.32, and a bypass ratio at cruise conditions is less than 12.
However, it is noted that applicant has not disclosed that having the ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being from 0.13 to 0.14 results in an unpredicted result not seen in the prior art and it appears that the invention of Savela and Moore would perform equally well with a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being from 0.13 to 0.14. Accordingly, it has been 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 (MPEP 2144.04(IV)(A)).
Walker teaches a gas turbine engine (Fig.1) including a fan (23), a gear (30), a low pressure compressor (14), a low pressure turbine (19) and a core shaft (26) connecting the low pressure compressor and turbine. Walker further teaches the fan blades have a hub-to-tip ratio in a range of from 0.28 to 0.32 (¶21), and a bypass ratio at cruise conditions is less than 12 (¶25).
It would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to further modify the gas turbine engine of Savela and Moore by the fan having a fan diameter greater than 220 cm based on the teachings of Walker because this would require a simple substitution of one known element (fan blades hub-to-tip ratio and bypass ratio at cruise of Savela and Moore) for another (fan blades hub-to-tip ratio and bypass ratio at cruise of Walker) to obtain a predictable results (operating a gas turbine engine to produce thrust to power an aircraft).
Regarding claim 16, Savela and Moore teach all the limitations of claim 1, see above, however, do not explicitly teach the gas turbine engine has a specific thrust at cruise conditions in a range of from 90 Nkg-1s to 110 Nkg-1s.
Walker teaches a gas turbine engine (Fig.1) including a fan (23), a gear (30), a low pressure compressor (14), a low pressure turbine (19) and a core shaft (26) connecting the low pressure compressor and turbine. Walker further teaches the gas turbine engine has a specific thrust at cruise conditions in a range of from 90 Nkg-1s to 110 Nkg-1s (¶27).
It would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to further modify the gas turbine engine of Savela and Moore by the gas turbine engine having a specific thrust at cruise conditions in a range of from 90 Nkg-1s to 110 Nkg-1s based on the teachings of Walker because this would require a simple substitution of one known element (specific thrust at cruise of Savela and Moore) for another (specific thrust at cruise of Walker) to obtain a predictable results (operating a gas turbine engine to produce thrust to power an aircraft).
Regarding claim 17, Savela, Moore and Walker teach all the limitations of claim 16, see above, however, does not explicitly teach the ratio of the minor span to core shaft length ratio to the minor span to turbine length ratio is in the range of from 0.05 to 0.14.
However, it is noted that applicant has not disclosed that having the ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being from 0.05 to 0.14 results in an unpredicted result not seen in the prior art and it appears that the invention of Savela, Moore and Walker would perform equally well with a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being from 0.05 to 0.14. Accordingly, it has been 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 (MPEP 2144.04(IV)(A)).
Regarding claim 18, Savela, Moore and Walker further teach the gearbox has a gear ratio greater than 3.1 (Savela ¶36, note “a gear reduction ratio of greater than about 2.5:1”).
Regarding claim 19, Savela, Moore and Walker teach all the limitations of claim 16, see above, however, does not explicitly teach the ratio of the minor span to core shaft length ratio to the minor span to turbine length ratio is in the range of from 0.05 to 0.13.
However, it is noted that applicant has not disclosed that having the ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being from 0.05 to 0.13 results in an unpredicted result not seen in the prior art and it appears that the invention of Savela, Moore and Walker would perform equally well with a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being from 0.05 to 0.13. Accordingly, it has been 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 (MPEP 2144.04(IV)(A)).
Regarding claim 20, Savela, Moore and Walker teach all the limitations of claim 16, see above, however, does not explicitly teach the ratio of the minor span to core shaft length ratio to the minor span to turbine length ratio is in the range of from 0.12 to 0.14, the specific thrust at cruise conditions is in a range of from 95 Nkg-1s to 110 Nkg-1s, and the gas turbine engine has an overall pressure ratio at cruise conditions in a range of from 40 to 65.
However, it is noted that applicant has not disclosed that having the ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being from 0.12 to 0.14results in an unpredicted result not seen in the prior art and it appears that the invention of Savela, Moore and Walker would perform equally well with a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being from 0.12 to 0.14. Accordingly, it has been 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 (MPEP 2144.04(IV)(A)).
Walker teaches a gas turbine engine (Fig.1) including a fan (23), a gear (30), a low pressure compressor (14), a low pressure turbine (19) and a core shaft (26) connecting the low pressure compressor and turbine. Walker further teaches the gas turbine engine has a specific thrust at cruise conditions in a range of from 90 Nkg-1s to 110 Nkg-1s (¶27), and the gas turbine engine has an overall pressure ratio at cruise conditions in a range of from 40 to 65 (¶26).
It would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to further modify the gas turbine engine of Savela, Moore and Walker by the gas turbine engine having a specific thrust at cruise conditions in a range of from 90 Nkg-1s to 110 Nkg-1s, and the gas turbine engine has an overall pressure ratio at cruise conditions in a range of from 40 to 65 based on the further teachings of Walker because this would require a simple substitution of one known element (specific thrust and overall pressure ratio at cruise of Savela and Moore) for another (specific thrust and overall pressure ratio at cruise of Walker) to obtain a predictable results (operating a gas turbine engine to produce thrust to power an aircraft).
Regarding claim 21, Savela, Moore and Walker teach all the limitations of claim 16, see above, however, does not explicitly teach the specific thrust is in a range of from 95 Nkg-1s to 110 Nkg-1s, the gas turbine engine has an overall pressure ratio at cruise conditions in a range of from 40 to 65, and a bypass ratio of the gas turbine engine at cruise conditions is in a range from 10 to 12.
Walker teaches a gas turbine engine (Fig.1) including a fan (23), a gear (30), a low pressure compressor (14), a low pressure turbine (19) and a core shaft (26) connecting the low pressure compressor and turbine. Walker further teaches the gas turbine engine has a specific thrust at cruise conditions in a range of from 90 Nkg-1s to 110 Nkg-1s (¶27), the gas turbine engine has an overall pressure ratio at cruise conditions in a range of from 40 to 65 (¶26), and a bypass ratio of the gas turbine engine at cruise conditions is in a range from 10 to 12 (¶25).
It would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to further modify the gas turbine engine of Savela, Moore and Walker by the gas turbine engine having a specific thrust at cruise conditions in a range of from 90 Nkg-1s to 110 Nkg-1s, and the gas turbine engine has an overall pressure ratio at cruise conditions in a range of from 40 to 65, and a bypass ratio of the gas turbine engine at cruise conditions is in a range from 10 to 12 based on the teachings of Walker because this would require a simple substitution of one known element (specific thrust, overall pressure ratio and bypass ratio at cruise of Savela and Moore) for another (specific thrust, overall pressure ratio and bypass ratio at cruise of Walker) to obtain a predictable results (operating a gas turbine engine to produce thrust to power an aircraft).
Claim(s) (examined as effectively filed on 20 June 2024) 22 is/are rejected under 35 U.S.C. 103 as being unpatentable over Gaskell et al – hereafter Gaskell – (US 20210190008 A1).
Regarding claim 22, Gaskell teaches a gas turbine engine (Fig.1) for an aircraft comprising:
an engine core (¶108) comprising:
a turbine that is a lowest pressure turbine of the gas turbine engine (¶108), the turbine having a turbine length defined as a distance between a root of a most upstream blade of the turbine at a leading edge thereof and a root of a most downstream blade of the turbine at a trailing edge thereof (¶108),
a compressor that is a lowest pressure compressor of the gas turbine engine (¶108),
a core shaft connecting the turbine to the compressor (¶108), and
three bearings arranged to support the core shaft, the three bearings comprising a forward bearing and two rearward bearings, with a minor span, S, being defined as an axial distance between the two rearward bearings (¶109);
a fan located upstream of the engine core, the fan comprising a plurality of fan blades (¶108);
and a gearbox configured to receive an input from the core shaft and output drive to the fan so as to drive the fan at a lower rotational speed than the core shaft (¶108),
wherein:
the core shaft has a length, L, between the forward bearing and a rearmost bearing of the two rearward bearings (¶119),
a minor span to turbine length ratio of:
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is equal to or less than 1.05 (¶109-110).
However, Gaskell does not explicitly teach a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio of:
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is in a range of 0.05 to 0.2.
However, it is noted that applicant has not disclosed that having the ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being in a range of 0.05 to 0.2 results in an unpredicted result not seen in the prior art and it appears that the invention of Gaskell would perform equally well with a ratio of a minor span to core shaft length ratio to a minor span to turbine length ratio being in a range of 0.05 to 0.2. Accordingly, it has been 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 (MPEP 2144.04(IV)(A)).
Allowable Subject Matter
Claim 23 (examined as effectively filed on 19 December 2019) is allowed.
The following is a statement of reasons for the indication of allowable subject matter.
The following claim limitations were not found in the prior art.
Gas turbine engine with three bearings comprising a forward bearing and two rearward bearings, with a minor span, S, being defined as an axial distance between the two rearward bearings, wherein a minor span to turbine length ratio of: (the minor span)/(the turbine length) is equal to or less than 1.05 (as in the context of claim 23).
A relevant prior art reference (Roberge US 20160195019 A1 & US 9,932,902 B2) teaches a gas turbine engine for an aircraft (Fig.1) comprising: an engine core (Fig.1) comprising a turbine (Fig.1/2A, 46/120), a compressor (Fig.1, 44), and a core shaft (Fig.1, 30/40) connecting the turbine to the compressor, the turbine being a lowest pressure turbine of the gas turbine engine (Fig.1/2A) and the compressor being a lowest pressure compressor of the gas turbine engine (Fig.1); and a fan (Fig.1, 42) located upstream of the engine core, the fan comprising a plurality of fan blades (Fig.1); a gearbox (Fig.1, 48) that is configured to receive an input from the core shaft and output drive to the fan so as to drive the fan at a lower rotational speed than the core shaft (Roberge 1137); wherein: the engine core further comprises three bearings arranged to support the core shaft (Fig.1/2A), the three bearings comprising a forward bearing (Fig.1, 38 adjacent numeral 48) and two rearward bearings (Fig.2A, 164/168) located downstream of a leading edge of a lowest pressure turbine blade of the turbine at a root of the blade, however, Roberge does not disclose or suggest the minor span to turbine length ratio.
Pointon (US 20180252166 A1) teaches gas turbine engine including a fan (Fig.1, 13) with a fan diameter in the range from 240 cm to 280 cm (142, note "exemplary gas turbine engines 10 the fan 13 has a diameter in the range of 95 inches to 150 inches"); and further teaches a fan tip loading greater than 0.29 (127), however, Pointon does not disclose or suggest the minor span to turbine length ratio.
No other prior art was found that would anticipate or allow the examiner establishing a prima facie case of obviousness in view of the cited prior art above.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to JUAN G FLORES whose telephone number is (571)272-3486. The examiner can normally be reached Monday - Friday, 8:30am - 5:30pm Pacific Time.
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/JUAN G FLORES/Primary Examiner, Art Unit 3745