DETAILED ACTION
This is a non-final rejection in response to RCE filed 1/29/26. Claims 1-3 and 5-21 are currently pending.
Response to Arguments
Applicant’s arguments with respect to claim(s) 1-3 and 5-21 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument.
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, 5-6, and 10-21 is/are rejected under 35 U.S.C. 103 as being unpatentable over Stearns et al. (US 8261527) in view of Bemment (US 2023/0323822).
Regarding independent claims 1 and 18, and dependent claims 2-3, 10-14, 17 and 20, Stearns teaches a method of operating a gas turbine engine 20 for an aircraft, the gas turbine engine comprising: an engine core comprising a turbine 54, a compressor 52, a combustor 56 arranged to combust a fuel, and a core shaft 50 connecting the turbine to the compressor; a fan 42 located upstream of the engine core; a gearbox 48 that receives an input from the core shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft (col. 4, ll. 3-24); an oil loop system 140 arranged to supply oil to the gearbox; and a heat exchange system comprising: an air-oil heat exchanger 68 through which the oil in the oil loop system flows; and a fuel-oil heat exchanger 144 through which the oil in the oil loop system and the fuel flow such that heat is transferred between the oil and the fuel, and wherein the oil loop system branches such that a proportion of the oil can flow along each branch and the air-oil and fuel-oil heat exchangers are arranged in a parallel configuration on different branches of the oil loop system (col. 5, ll. 14-26, and figure 2); and a modulation valve 76 arranged to allow the proportion of the oil sent via each branch to be varied (col. 5, ll. 14-26).
Stearns is silent to controlling the heat exchange system such that, under idle conditions, a rate of heat transfer from oil to air (kJkg-1) / rate of heat transfer from oil to fuel (kJkg-1) is in the range from 0.67 to 5.67 when the fuel comprises sustainable aviation fuel, and the heat transfer ratio varies within the range from 0.67 to 5.67 based on a percentage of the sustainable aviation fuel provided to the combustor.
However, Bemment teaches determining one or more fuel characteristic to be combusted, including the percentage of SAF [0345,0362,0649], modifying a control parameter of a heat management system of the aircraft based on one or more fuel characteristics [0649], wherein SAF may comprise higher thermal stability relative to hydrocarbon fuels, allowing the fuel to systain elevated temperatures without significantly increasing fuel breakdown products [0336,0343], and controlling the propulsion system such that heat management parameters are adjusted based on the %SAF [0574-0596, 0649-0650].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the gas turbine engine of Stearns by incorporating the fuel-characteristic-based control teachings of Bemment. Specifically using an SAF fuel and determining the % SAF of the fuel being combusted [0345] and adjusting the control modulation valve of Stearns based on the determined % SAF to vary the heat transfer ratio between the air-oil and the fuel-oil heat exchangers. Bemment further teaches SAF has higher thermal stability than conventional fuel [0336,0343], therefore ithe engine can safely transfer more heat to the fuel without risking coking, whereas with conventional fuel, more heat may need to be rejected.
Regarding the numerical range of 0.67 to 5.67 at idle conditions, while this range is not specifically taught, Bemment teaches specific thermal properties of oil and fuel used, particularly SAF thermal stability as mentioned above. Bemment also teaches maximum allowable fuel temperature to prevent coking or thermal degradation [0336]. Optimization of operational parameters such as flow split ratios and resulting heat transfer ratios to achieve desired thermal performance is routine engineering activity.
In this case, the recognized result represents the combination of Stearns and Bemment recognizes that the heat transfer ratio influences known results. Stearns teaches controlling this balance to manage oil and fuel temperatures (col. 5, l. 28-35). Bemment further teaches that fuel characteristics directly influence the allowable fuel temperature, thus the optimal heat split to prevent coking while maximizing efficiency [0459,0649]. Therefore, one of ordinary skill would recognize heat transfer ratio as a variable that influences the result of thermal management efficacy. Additionally, the general condition of controlling heat exchange based on fuel type is taught by Bemment [0649] and the general condition of controlling heat transfer ratio via modulation is taught by Stearns (col. 5, ll. 14-26).
The heat transfer ratio at a particular condition is recognized as a result-effective variable, i.e. a variable which achieves a recognized result. In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977); MPEP 2144.05(II)(B).
Since the general conditions of the claim, i.e. that a certain range of the heat transfer ratio is present and that varying the heat transfer ratio in order to control the temperature of oil, temperature of fuel and fuel consumption were disclosed in the prior art, 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 at the time of the invention to provide the claimed ratio, i.e. 0.67 to 5.67 for claim 1, below 5.5 for claim 2, below 5.0 for claim 3, 0.67 to 4 for claim 9, 3.37 to 5.67 for claim 10, 0.67 to 3.67 for claim 15 and >0.75 for claim 17, 2.33 to 5.67 (claim 11), 0.67 to 4 (claim 12), 0.67 to 2.67 (claim 13, 16), 0.67 to 1.22 (claim 14) and when temperature being <200C (claim 11), >200C (claim 12), >250C (claim 13) or >280C (claim 14) and when fuel is at least 70% sustainable aviation fuel (claim 15) or fuel is at least 80% sustainable aviation fuel (claim 16). Since it has been held that optimizing a result effective variable was an obvious extension of prior art teachings, In re Antoine, 559 F.2d 618, 195 USPQ 6 (CCPA 1977), In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955),“[W]here 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.” MPEP 2144.05 I and II.
Regarding dependent claim 5, Stearns in view of Bemment teaches the invention as claimed and discussed above. Stearns further teaches wherein the controlling the heat exchange system so as to adjust the heat transfer ratio comprises decreasing the amount of oil sent via the at least one air-oil heat exchanger when the heat transfer ratio is too high (col. 5, ll. 36-54).
Regarding dependent claim 6, Stearns in view of Bemment teaches the invention as claimed and discussed above. Stearns further teaches wherein the bypass pipe is arranged to allow a proportion of the oil to flow past the air-oil heat exchanger, such that oil flowing through the bypass pipe flows through the fuel-oil heat exchanger without flowing through the air-oil heat exchanger, and wherein the controlling the heat exchange system so as to adjust the heat transfer ratio comprises increasing the amount of oil flowing through the bypass pipe when the heat transfer ratio is too high. As seen in figure 2, the oil can bypass the AOC (bypass valve 76, col. 5, ll. 36-54).
Regarding dependent claims 15-16, Stearns in view of Bemment teaches the invention as claimed and discussed above. Bemment further teaches wherein, under cruise conditions, the method comprises controlling the heat exchange system such that the heat transfer ratio is in a predetermined range ([0039-0048], Figs. 2-5), provided that the fuel is at least a certain percentage sustainable aviation fuel.
Stearns in view of Bemment, as modified above teaches the predetermined range being 0.67 to 3.67, 0.67 to 2.67, the percentage of sustainable fuel being at least 70% and 80% [Bemment, 0135].
Regarding dependent claim 19, Stearns in view of Bemment teaches the invention as claimed and discussed above. Stearns further teaches wherein: the turbine is a first turbine 46, the compressor is a first compressor 44, and the core shaft is a first core shaft 40; the engine core further comprises a second turbine 54, a second compressor 52, and a second core shaft 50 connecting the second turbine to the second compressor; and the second turbine, second compressor, and second core shaft are arranged to rotate at a higher rotational speed than the first core shaft (col. 3, ll. 40-61).
Regarding independent claim 21, Stearns teaches a method of operating a gas turbine engine 20 for an aircraft, the gas turbine engine comprising: an engine core comprising a turbine 54, a compressor 52, a combustor 56 arranged to combust a fuel, and a core shaft 50 connecting the turbine to the compressor; a fan 42 located upstream of the engine core; a gearbox 48 that receives an input from the core shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft (col. 4, ll. 3-24); an oil loop system 140 arranged to supply oil to the gearbox; and a heat exchange system comprising: an air-oil heat exchanger 68 through which the oil in the oil loop system flows; and a fuel-oil heat exchanger 144 through which the oil in the oil loop system and the fuel flow such that heat is transferred between the oil and the fuel, and wherein the oil loop system branches such that a proportion of the oil can flow along each branch and the air-oil and fuel-oil heat exchangers are arranged in a parallel configuration on different branches of the oil loop system (col. 5, ll. 14-26, and figure 2); and a modulation valve 76 arranged to allow the proportion of the oil sent via each branch to be varied (col. 5, ll. 14-26).
Stearns is silent to controlling the heat exchange system such that, under idle conditions, a rate of heat transfer from oil to air (kJkg-1) / rate of heat transfer from oil to fuel (kJkg-1) is in the range from 0.67 to 5.67 when the fuel comprises sustainable aviation fuel, and the heat transfer ratio varies within the range from 0.67 to 4.0 when the fuel temperature on entry to the combustor is a
However, Bemment teaches determining one or more fuel characteristic to be combusted, including the percentage of SAF [0345,0362,0649], modifying a control parameter of a heat management system of the aircraft based on one or more fuel characteristics [0649], wherein SAF may comprise higher thermal stability relative to hydrocarbon fuels, allowing the fuel to systain elevated temperatures without significantly increasing fuel breakdown products [0336,0343], and controlling the propulsion system such that heat management parameters are adjusted based on the %SAF [0574-0596, 0649-0650].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the gas turbine engine of Stearns by incorporating the fuel-characteristic-based control teachings of Bemment. Specifically using an SAF fuel and determining the % SAF of the fuel being combusted [0345] and adjusting the control modulation valve of Stearns based on the determined % SAF to vary the heat transfer ratio between the air-oil and the fuel-oil heat exchangers. Bemment further teaches SAF has higher thermal stability than conventional fuel [0336,0343], therefore ithe engine can safely transfer more heat to the fuel without risking coking, whereas with conventional fuel, more heat may need to be rejected.
Regarding the numerical range of 00.67 to 5.67, and controlled to be 0.67 to 4 under idle conditions when the fuel temperature on entry to the combustor is above 200C, while this range is not specifically taught, Bemment teaches specific thermal properties of oil and fuel used, particularly SAF thermal stability as mentioned above. Bemment also teaches maximum allowable fuel temperature to prevent coking or thermal degradation [0336]. Optimization of operational parameters such as flow split ratios and resulting heat transfer ratios to achieve desired thermal performance is routine engineering activity.
In this case, the recognized result represents the combination of Stearns and Bemment recognizes that the heat transfer ratio influences known results. Stearns teaches controlling this balance to manage oil and fuel temperatures (col. 5, l. 28-35). Bemment further teaches that fuel characteristics directly influence the allowable fuel temperature, thus the optimal heat split to prevent coking while maximizing efficiency [0459,0649]. Therefore, one of ordinary skill would recognize heat transfer ratio as a variable that influences the result of thermal management efficacy. Additionally, the general condition of controlling heat exchange based on fuel type is taught by Bemment [0649] and the general condition of controlling heat transfer ratio via modulation is taught by Stearns (col. 5, ll. 14-26).
The heat transfer ratio at a particular condition is recognized as a result-effective variable, i.e. a variable which achieves a recognized result. In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977); MPEP 2144.05(II)(B).
Since the general conditions of the claim, i.e. that a certain range of the heat transfer ratio is present and that varying the heat transfer ratio in order to control the temperature of oil, temperature of fuel and fuel consumption were disclosed in the prior art, 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 at the time of the invention to provide the claimed ratio, i.e. 0.67 to 5.67, and controlled to be 0.67 to 4 under idle conditions when the fuel temperature on entry to the combustor is above 200C. Since it has been held that optimizing a result effective variable was an obvious extension of prior art teachings, In re Antoine, 559 F.2d 618, 195 USPQ 6 (CCPA 1977), In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955),“[W]here 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.” MPEP 2144.05 I and II.
Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over Stearns in view of Bemment and further in view of Cass (US 6189313).
Regarding dependent claim 7, Stearns in view of Bemment teaches the invention as claimed and discussed above. Stearns in view of Bemment is silent to wherein the heat exchange system comprises at least one recirculation pipe arranged to allow a fluid to pass through a heat exchanger multiple times, and wherein the controlling the heat exchange system so as to adjust the heat transfer ratio comprises modulating the amount of the fluid sent via the recirculation pipe.
However, Cass teaches an aircraft engine 40 and method of operation (the disclosure of the engine discloses its method of operation) having a heat exchange system (see fig. 1) comprises at least one recirculation pipe 28, 32, 38 arranged to allow a fluid 22 to pass through a heat exchanger 20 multiple times, and modulating the amount of the fluid sent via the recirculation pipe (see 26 and valves on recirculation pipes that control the amount of fuel recirculating).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified heat exchange system of Stearns in view of Bemment to have at least one recirculation pipe arranged to allow a fluid to pass through a heat exchanger multiple times, and modulating the amount of the fluid sent via the recirculation pipe, as taught by Cass. Such a modification would improve repairability and maintenance (col. 1, ll. 10-29).
Claim 8-9 are rejected under 35 U.S.C. 103 as being unpatentable over Stearns in view of Bemment and further in view of Snape et al. (US 2018/0080688).
Regarding dependent claim 8, Stearns in view of Bemment teaches the invention as claimed and discussed above. Stearns in view of Bemment is silent to wherein the heat exchange system further comprises a refrigeration cycle apparatus, and the controlling the heat exchange system comprises using the refrigeration cycle apparatus to provide thermal lift by transferring further heat from the oil to the fuel such that the fuel temperature is raised above the oil temperature.
Snape teaches wherein the heat exchange system further comprises a refrigeration cycle apparatus, and the controlling the heat exchange system comprises using the refrigeration cycle apparatus to provide thermal lift by transferring further heat from the oil to the fuel such that the fuel temperature is raised above the oil temperature [0040-0043].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the gas turbine engine of Stearns in view of Bemment to have a refrigeration cycle apparatus as claimed in order to provide thermal lift, as taught by Snape, as Snape teaches thermal lift, which results in increased heat transfer [0041].
Regarding dependent claim 9, Stearns in view of Bemment and further in view of Snape teaches the invention as claimed and discussed above. Stearns in view of Bemment and further in view of Snape is silent to controlling the heat exchange system such that the heat transfer ratio is in the range from 0.67 to 4.
Regarding the numerical range of 0.67 to 4 at idle conditions, while this range is not specifically taught, Bemment teaches specific thermal properties of oil and fuel used, particularly SAF thermal stability as mentioned above. Bemment also teaches maximum allowable fuel temperature to prevent coking or thermal degradation [0336]. Optimization of operational parameters such as flow split ratios and resulting heat transfer ratios to achieve desired thermal performance is routine engineering activity.
In this case, the recognized result represents the combination of Stearns and Bemment and further in view of Snape recognizes that the heat transfer ratio influences known results. Stearns teaches controlling this balance to manage oil and fuel temperatures (col. 5, l. 28-35). Bemment further teaches that fuel characteristics directly influence the allowable fuel temperature, thus the optimal heat split to prevent coking while maximizing efficiency [0459,0649]. Therefore, one of ordinary skill would recognize heat transfer ratio as a variable that influences the result of thermal management efficacy. Additionally, the general condition of controlling heat exchange based on fuel type is taught by Bemment [0649] and the general condition of controlling heat transfer ratio via modulation is taught by Stearns (col. 5, ll. 14-26).
The heat transfer ratio at a particular condition is recognized as a result-effective variable, i.e. a variable which achieves a recognized result. In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977); MPEP 2144.05(II)(B).
Since the general conditions of the claim, i.e. that a certain range of the heat transfer ratio is present and that varying the heat transfer ratio in order to control the temperature of oil, temperature of fuel and fuel consumption were disclosed in the prior art, 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 at the time of the invention to provide the claimed ratio, i.e. 0.67 to 4. Since it has been held that optimizing a result effective variable was an obvious extension of prior art teachings, In re Antoine, 559 F.2d 618, 195 USPQ 6 (CCPA 1977), In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955),“[W]here 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.” MPEP 2144.05 I and II.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to CRAIG SANG KIM whose telephone number is (571)270-1418. The examiner can normally be reached 7:00 AM - 3:00 PM.
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/CRAIG KIM/
Primary Examiner
Art Unit 3741