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 Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-20 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
Claim 1 recites “the first loop including a first air-lubricant heat exchanger, which is adapted to receive cooling air from a bypass duct to dissipate heat to bypass air, the first loop not including a fuel-lubricant heat exchanger such that heat generated by the turbomachinery bearings is dissipated to the bypass air and not to any fuel-lubricant heat exchanger” (the underlining showing the newly amended text). Applicant has stated on page 10 of the Remarks filed 03/16/2026 that support for the instant newly amended phrase is in fig. 8 and pars. 6, 23 and 62 of PGPub 20240110517. Fig. 8 shows a lubricant tank 120 common to both the first loop 414 and the second loop 415. Thus heat generated by the gearbox 430 could be dissipated by fuel-lubricant heat exchanger 105 of the second loop 415 because the two loops are thermally coupled by way of the common tank 120. Regarding additional more specific discussion, some of the heat dissipated by the turbomachinery bearings 430 may be carried by the lubricant to the tank 120 where such lubricant may then be carried to the claimed second loop 415 (referred to as second lubrication circuit 415 in par. [0529]) and dissipated or partially dissipated therein (the oil heated by the turbomachinery bearings goes to the tank 120 before reaching the first lubricant heat exchanger 104; also see par. [0529]: “one single tank 120 supplies lubricant to both the first lubricant circuit 414 and the second lubricant circuit 415”).
It is noted that par. 529 points out that each of the first loop 414 and the second loop 415 may have a dedicated lubricant tank in alternative embodiments. However, there is no additional discussion or drawings of such alternative embodiments regarding the form of the dedicated lubricant tanks. For example if the two dedicated lubricant tanks are in a common casing the two tanks would be thermally coupled and thus heat generated by the bearings 430 could be dissipated by fuel-lubricant exchanger 105. Therefore the instant recitation is considered new matter. For purposes of examination the claim is interpreted consistent with applicant fig. 8 that is cited in the instant Remarks discussed above.
Claim 18 recites a similar limitation and is rejected for the same reasons. It is noted applicant elected fig. 8 in the response (filed 10/01/2024) to the restriction requirement mailed 09/05/2024.
Claim 1 recites “to prevent thermal degradation of stagnant fuel”. Applicant remarks state support is in par. 6. Par. 6 recites “in fuel spray nozzles with pilot and mains streams, when the mains stream is staged out (turned off), the fuel in the mains stream is generally stagnant and therefore picks up heat which is undesirable due to fuel thermal degradation.” Thus there is support for “generally stagnant”. This general condition does not necessarily include the condition of “stagnant fuel”. For example when fuel flow is off there may still me fuel movement due to other structures. For example see Pub. No. US 20100115956 A1 (Toon) par. 28 that points out “geometries can allow fuel to drain fully from the passage when the flow of fuel is stopped. This helps to prevent trapped fuel coking in and blocking the passage when the main fuel is stopped (staged) below full engine power and the engine operates with pilot fuel only”. One of ordinary skill in the art understands that coking of fuel is a type of fuel degradation. For example, Toon in par. 46 goes on to mention “fuel in the mains gallery should drain away completely to prevent stagnant fuel thermally degrading in the gallery and forming coke.” Thus “stagnant” fuel would mean fuel not in movement and “generally stagnant” can communicate the condition of fuel when fuel flow to the engine shutoff but fuel is permitted to otherwise move. Claim 18 recites a similar limitation and is rejected for the same reasons.
Claims dependent thereon are rejected for the same reasons.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1-20 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 1 recites “the range is configured to set a minimum portion of heat to be dissipated to air rather than to fuel”. The metes and bounds of the claim are unclear because one of ordinary skill in the art would not understand the scope of “minimum portion of heat”. There is no discussion of a minimum portion of heat is applicant disclosure. The term minimum can be interpreted as “Of, consisting of, or representing the lowest possible amount or degree permissible or attainable”. Thus minimum could refer to as the minimum amount of heat attainable (for example in a very cold climate it could be possible that only 0% or 10% of heat dissipated to the air-lubricant heat exchangers could protect against degradation of thermal fuel. For example, applicant disclosure cites 20% (i.e. 0.20) in par. 35 as an example however applicant disclosure does not specify the minimum portion relating the specific case of thermal degradation of stagnant fuel discussed in par. 6. In contrast to the above discussion of 20%, applicant states in the remarks on pages 13 bottom and 14 top that 25% of the heat generated by the power gearbox and the bearings is the minimum amount of heat to be dissipated to air in order to prevent thermal degradation of stagnant fuel. Thus one of ordinary skill in the art would not be able to understand how to avoid infringing the claim. Claim 18 recites a similar limitation and is rejected for the same reasons.
Claims dependent thereon are rejected for the same reasons.
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, 2, 7, 13-16 and 18 is/are rejected under 35 U.S.C. 103 as being unpatentable over Pub. No.: US 2021/0190008 A1 (Gaskell) in view of Pub. No.: US 2015/0361811 A1 (Schwarz) as evidenced by US 2014/0090395 A1 (Appukuttan), Pub. No.: US 2019/0145317 A1 (Holt), Pub. No. US 2020/0011273 A1 (Baralon), Pub. No.: US 2022/0403779 A1 (Walz) and Pub. No.: US 2021/0172375 A1 (Bosak).
Regarding claims 1, 2 and 7, Gaskell discloses (see fig. 1) a method of operating a gas turbine engine 10 for an aircraft (see abstract), the method comprising providing a gas turbine engine 10 comprising:
- an engine core 11 comprising a compressor 14,15, a combustor 16, a turbine 17,19, and a core shaft 26 connecting the turbine 19 to the compressor 14;
- a fan 23 comprising a plurality of fan blades (at 23) and arranged upstream (with respect to stream B) of the engine core 11;
- turbomachinery bearings (see annotated figure below);
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[AltContent: textbox (bearings)][AltContent: arrow][AltContent: textbox (bearings)][AltContent: arrow][AltContent: arrow][AltContent: textbox (bearings)][AltContent: arrow][AltContent: arrow]
- a power gearbox 30 adapted to drive the fan 23 at a lower rotation speed (see par. 10) than the turbine 19; and
- a heat management system configured to provide lubrication and cooling to the turbomachinery bearings (see par. 360 and 367 stating that oil is used for lubricating bearings and thus a lubrication system is provided; one of ordinary skill understands that heat will be transferred to the oil when the oil is at a lower temperature than the bearing for example, and thus the limitation regarding cooling the bearings is met), 85% of the core shaft maximum take-off speed (see par. 118; par. 118 discusses the operating range of the core shaft from 1500 rpm to 6200 rpm, the upper bound 6200 rpm being that speed reached at maximum take-off; therefore the speed of 85% of the core shaft maximum take-off speed would be reached at least during the increase from the lower bound of 1500 rpm to the maximum speed at take-off).
Gaskell does not explicitly disclose the heat management system configured to provide lubrication and cooling to the gearbox, and comprising a pipe assembly adapted to provide a lubricant flow to the gearbox and turbomachinery bearings,
wherein the lubricant flow includes a first loop connected to the turbomachinery bearings and a second loop connected to the gearbox,
the first loop including a first air-lubricant heat exchanger, which is adapted to receive cooling air from a bypass duct to dissipate heat to bypass air, the first loop not including a fuel-lubricant heat exchanger such that heat generated by the turbomachinery bearings is dissipated to the bypass air and not to any fuel-lubricant heat exchanger,
the second loop including a second air-lubricant heat exchanger, which is adapted to receive cooling air from the bypass duct to dissipate heat to the bypass air, at least one fuel-lubricant heat exchanger to dissipate heat to fuel, and a connecting path directly connecting the second air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger, the second air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger in the second loop are arranged in series, and
each of the first and second air-lubricant heat exchangers is a Matrix Air- Cooled Oil Cooler (MACOC), wherein: a first amount of heat is a sum of (i) a total amount of heat generated by the turbomachinery bearings all of which is dissipated to the bypass air via the first air-lubricant heat exchanger and (ii) a portion of heat generated by the gearbox that is dissipated to the bypass air via the second air-lubricant heat exchanger; a second amount of heat is another portion of the heat generated by the gearbox that is dissipated to the fuel via the at least one fuel-lubricant heat exchanger;
the method further comprising:
- operating the heat management system to provide the first amount of heat and the second amount of heat such that a first proportion defined as
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85%MTO at 85% of a core shaft maximum take-off speed is in the range of from 0.25 to 0.70; and
- operating the fan at cruise condition to provide a fan pressure ratio in the range of from 1.35 to 1.43 (more specifically Gaskell is silent the value of the fan pressure ratio).
Schwarz teaches (see figs. 1 and 9) a gas turbine 20 and further teaches a heat management system 180 configured to provide lubrication (via pipes 95 and 109 and lubrication pumps 182,184) and cooling (see discussion of heat exchangers below) to a gearbox 32 (and bearings 64), and comprising a pipe assembly 95,109 adapted to provide a lubricant flow to the gearbox 32 and turbomachinery bearings 64, at least one air-lubricant heat exchanger 92,106 adapted to receive cooling air (cooling air is from bypass gas path 68 in fig. 1; see par. 47 regarding exchanger 92, and see par. 48 regarding exchanger 106) from a bypass duct (duct at 68 in fig. 1) to dissipate a first amount (see thermal loads dissipated as heat energy in par. 44) of heat to a first heat sink (air from air valves 80,82; see pars. 47 and 48),
wherein the first heat sink (air from air valves 80,82; see pars. 47 and 48) is bypass air 68,
wherein a lubricant flow includes a first loop 78’’’ connected to the turbomachinery bearings 64 and a second loop 76 ‘’’ connected to the gearbox 32, the first loop 78’’’ including a first air-lubricant heat exchanger 106, which is adapted to receive cooling air (cooling air is from bypass gas path 68 in fig. 1; see par. 47 regarding exchanger 92, and see par. 48 regarding exchanger 106) from a bypass duct (duct at 68 in fig. 1) to dissipate heat (see thermal loads dissipated as heat energy in par. 44) to bypass air (air from air valves 80,82; see pars. 47 and 48), the first loop 78’’’ not including a fuel-lubricant heat exchanger (see fig. 9 wherein there is no fuel-lubricant heat exchanger) such that all of heat (in the same manner that applicant claims that all the heat is given to the bypass air; see 112 section above) generated by the turbomachinery bearings 64 is dissipated to the bypass air (air from air valves 80,82; see pars. 47 and 48) and not (there is not a fuel-lubricant heat exchanger in first loop 78’’’ in Schwarz fig. 9 ) to any fuel-lubricant heat exchanger (in the same manner that applicant claims and discloses that not any heat is dissipated to any fuel-lubricant heat exchanger; i.e. there is no fuel-lubricant heat exchanger in first loop 414 in applicant fig. 8; see 112 section above regarding new matter and claim interpretation),
and the second loop 76 ‘’’ including a second air-lubricant heat exchanger 92, which is adapted to receive cooling air (cooling air is from bypass gas path 68 in fig. 1; see par. 47 regarding exchanger 92, and see par. 48 regarding exchanger 106) from the bypass duct (duct at 68 in fig. 1) to dissipate heat to the bypass air (air from air valves 80,82; see pars. 47 and 48).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to provide Gaskell with the gearbox and bearing cooling system of Schwarz in order to facilitate improved lubrication and cooling (see Schwarz pars. 5-6).
Schwarz embodiment of fig. 10 teaches a heat management system 180 with a second loop 76IV (connected to turbomachinery gearbox 32 and in addition to a first loop 78IV) and further teaches at least one fuel-lubricant heat exchanger 146 to dissipate heat (see par. 12) to fuel (fuel of the at least one fuel-lubricant heat exchanger, see pars. 54 and 57; the heat exchanger removes heat from lubricant that is heated by the engine, see par. 49, bottom; such heat is removed from the lubricant by fuel by way of the passages of the at least one fuel-lubricant heat exchanger 146,148, see pars. 54 and 57), and a connecting path (pipe at location 95) directly connecting an air-lubricant heat exchanger 92 and the at least one fuel-lubricant heat exchanger 146, the air-lubricant heat exchanger 92 and the at least one fuel-lubricant heat exchanger 146 in the second loop are arranged in series (see 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 Gaskell in view of Schwarz with at least one fuel-lubricant heat exchanger to dissipate heat to fuel, and a connecting path directly connecting the second air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger, the second air-lubricant heat exchanger and the at least one fuel- lubricant heat exchanger in the second loop are arranged in series as taught by Schwarz in order to facilitate further improved lubrication and cooling (see Schwarz pars. 5-6). Including the instant fuel-lubricant heat exchanger permits the heat management system of the combination to keep the energy dissipated by the fuel in the gas turbine system and thus represents an improvement in efficiency compared to waste heat dissipated to air in the bypass duct and then to the environment.
Holt teaches (see fig. 1) a gas turbine and further teaches an air-lubricant heat exchanger 24 is a Matrix Air-Cooled Oil Cooler (MACOC) 24 (see par. 32, top). 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 MACOC type of air-lubricant heat exchanger of Holt for the type (Schwarz teaches the type can be a tube and fin type as an example; see par. 41, top and par. 44, top) of each of the first and second air-lubricant heat exchangers of Gaskell in view of Schwarz for the purpose of substituting one known element for another in order to provide the expected result of providing a structure to exchange heat between air and lubricant.
Baralon teaches (see fig. 1) a gas turbine 18 and further teaches operating a fan 23 (of gas turbine 18) at cruise condition (see that the operating point in par. 57 is cruise; see par. 30) to provide a fan pressure ratio in the range of from 1.35 to 1.43 (see par. 57) and thus Baralon teaches a gas turbine with a known value of fan pressure ratio at cruise condition. 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 value of the fan pressure ratio at cruise of Baralon for the fan pressure ratio at cruise of the Gaskell in view of Schwarz and Holt (Gaskell being silent the value fan pressure ratio) for the purpose of substituting one known element for another in order to provide the expected result of a known pressure differential or in other words a known fan pressure ratio (see par. 57 of Baralon) across the fan of the combination to provide propulsive thrust (see par. 115, bottom, of Baralon). This results in operating the fan of Gaskell in view of Schwarz, Holt and Baralon being configured to provide at cruise condition to provide a fan pressure ratio in the range of from 1.35 to 1.43.
The combination of Gaskell in view of Schwarz, Holt and Baralon teach wherein: a first amount of heat (see thermal loads dissipated as heat energy in Schwarz par. 44) is a sum of (i) a total amount (see 112 section above regarding interpretation) of heat generated by the turbomachinery bearings 64 (see Schwarz fig. 9) all of which (see 112 section above regarding interpretation) is dissipated to the bypass air (air through valve 82) (it is noted that the arrangement of the prior art combination is that same as the instant invention and thus operates in the same functional manner regarding the claimed total amount of heat generated by the bearings as explained in the 112 section above and regarding the instant functional limitations; see MPEP 2112.01) via the first air-lubricant heat exchanger 106 and (ii) a portion of heat (see thermal loads dissipated as heat energy in Schwarz par. 44) generated by the gearbox 32 (see Schwarz fig. 9) that is dissipated to the bypass air (air through valve 80) via the second air-lubricant heat exchanger 92 (see Schwarz fig. 9); a second amount of heat (see thermal loads dissipated as heat energy in Schwarz par. 44) is another portion of the heat generated by the gearbox 32 (see Schwarz fig. 9) that is dissipated to the fuel (fuel shown as horizontal arrows through lubricant heat exchanger 146 in Schwarz fig. 10; heat is dissipated to fuel, e.g., see par. 61, bottom) via the at least one fuel-lubricant heat exchanger 146 (see Schwarz fig. 10); - operating the heat management system (taught by Gaskell and Schwarz as discussed above) to provide the first amount of heat (from air-lubricant heat exchangers 92,106 in Schwarz fig. 10) and the second amount of heat (from fuel-lubricant heat exchanger 146 in Schwarz fig. 10) such that a first proportion defined as
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85%MTO at 85% of a core shaft maximum take-off speed (85% of the 6200 rpm MTO, see pars. 118 and 165, of Gaskell is 5270 rpm that is just below cruise operating condition of 5400 rpm discussed in par. 164 of Gaskell; the Gaskell core shaft has a running speed in the range of 1500 rpm to 6200 rpm, see par. 21, and thus Gaskell operates at the instant 85% value of 5270 rpm and thus one of ordinary skill understands that the heat management system of the combination is used to dissipate heat at the instant rpm); and (claim 7) such that a second proportion of heat generated by the gearbox and the turbomachinery and dissipated to air defined as
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65%MTO at 65% of a core shaft maximum take-off speed (65% of the 6200 rpm MTO, see pars. 118 and 165, of Gaskell is 4060 rpm; the Gaskell core shaft has a running speed in the range of 1500 rpm to 6200 rpm, see par. 21, and thus Gaskell operates at the instant 65% value of 4060 rpm and thus one of ordinary skill understands that the heat management system of the combination is used to dissipate heat at the instant rpm).
Regarding claims 1, 2 and 7, Gaskell in view of Schwarz, Holt and Baralon teach all the features of the claimed invention except wherein (claim 1) the first proportion is in the range of from 0.25 to 0.70; (claim 2) the first proportion is in the range of from 0.35 to 0.70; and (claim 7) the second proportion is in the range of from 0.60 to 1.
Here, Walz and Bosak teach that the first proportion is result effective across engine operation rpm ranges. The first proportion can be thought of as the comparison of heat transferred from the oil to the at least one fuel-lubricant heat exchanger compared to that transferred by the oil to the at least one first air-lubricant heat exchanger (see instant application publication PGPub US 2024/0110517 A1 at pars. 12-14). As an overall idea, it is preferred to use the at least one fuel-lubricant heat exchanger to dissipate heat from the oil. This preserves energy from the engine system by using waste heat from the oil (see Bosak par. 6) and makes the engine more efficient (see Walz pars. 30 and 35) including improving fuel consumption (see Bosak par. 6). However, Bosak further points out (see par. 41) that too much heating of fuel with a fuel-lubricant heat exchanger results in coking and can damage the fuel equipment. Therefore, (see Walz fig. 2) oil flow through an air-lubricant heat exchanger 41 and a fuel-lubricant heat exchanger 42 can include a bypass circuit 35 that bypasses the air-lubricant heat exchanger 41 using variable bypass valve 36 (also see par. 47 pointing out that the bypass valve can be variable) to vary the respective oil flows through the respective heat exchangers (one of ordinary skill understands that the amount of oil flow corresponds to or relates to the amount of heat; see Pertinent Prior Art section on pages 28-29 in the office action mailed 11/22/2024). However, if too much oil is directed to the at air-lubricant heat exchanger, there will not be enough heat remaining in the oil at the exit of the air-lubricant heat exchanger to properly heat the fuel with the fuel-lubricant heat exchanger when the gas turbine is operating in a cold operating condition as pointed out by Walz in pars. 2, 37 and 38. Finally, Walz points out that proper balance of heat dissipated to air and fuel, across engine operating conditions, is necessary to avoid overdesigned or heavy equipment (see pars. 2 and 39). Bosak adds that in some scenarios it is more efficient for the engine to dissipate more heat to air rather than to fuel because this can keep the oil from degrading at high temperatures that happens when more emphasis it put on keeping energy in the engine system using the fuel-lubricant heat exchanger (see Bosak pars. 5, 12 and 38, bottom, and 48). Bosak accomplishes this by adjusting the speed of lubricant pumps 14,16 to respective heat exchangers 22,24 as shown in figs. 1 and 9. Thus, ratios of the first amount of heat to the second amount of heat control, or have an effect on, the efficiency of operation of a gas turbine, the durability of the fuel equipment, the quality of the lubricant and the capability of a heat management system to provide enough air and fuel to effectively cool the engine oil across engine operating conditions. A recognition in the prior art that a property is affected by the variable is sufficient to find the variable result-effective (MPEP 2144.05 III. C.).
Therefore, an ordinary skilled worker would recognize that the first proportion represented by the percentage of heat from oil transferred to the at least one first air-lubricant heat exchangers compared to that transferred to the at least one fuel-lubricant heat exchanger is a result effective variable. The prior art also teaches that the such a proportion is important at gas turbine engine operating ranges. See Bosak Figure 4 explaining when it can be more efficient, regarding operational scenarios such as idle and takeoff power of the engine, to emphasize average oil temperature and thus there is minimal impact on thrust specific fuel consumption.
Thus, the claimed wherein (claim 1) the first proportion is in the range of from 0.25 to 0.70, (claim 2) the first proportion is in the range of from 0.35 to 0.70 and (claim 7) the second proportion is in the range of from 0.60 to 1 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., the at least one first air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger are configured to provide the first amount of heat and the second amount of heat, were taught in the prior art by Gaskell in view of Schwarz, Holt and Baralon, 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 Gaskell in view of Schwarz, Holt and Baralon’s invention to include wherein the (claim 1) first proportion is in the range of from 0.25 to 0.70, the (claim 2) first proportion is in the range of from 0.23 to 0.70 and (claim 7) the second proportion is in the range of from 0.60 to 1 in order to provide an efficient and cost effective heat management system that adapts to engine operating conditions as suggested and taught by Walz and Bosak. 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).
One of ordinary skill is likely to be able to achieve this range (MPEP 2144.05 II.B.) because of the following reasons:
Applicant is not using a specific precise control algorithm with a computer controller to operate applicant heat management system. For example, applicant fuel-lubricant heat exchanger (shell and tube heat exchanger a plate-fin heat exchanger) is conventional (see pertinent prior art section in the office action mailed 07/08/2025 on page 43). Also applicant is not using a special fuel or lubricant that would change heat transfer properties.
The core speed running shaft speeds of 65%MTO and 85%MTO are common operating scenarios of flight idle and cruise;
The flow of oil in the first circuit 78’’’ and the second circuit 76’’’ (see Schwarz fig. 9) can be varied:
pumps 182 and 184 in fig. 9 of Schwarz; the pumps can be electrical pumps (see par. 33) and thus can have different speeds and thus pump different amounts of oil into the two circuits 78’’’ and 76’’’ (see fig. 9); this is discussed regarding Bosak above.
bypass valve 136 of Walz that has intermediate positions between open and closed; see par. 47; the valve can vary the amount of oil entering the at air-lubricant heat exchanger 92 (see Schwarz fig. 9) in the second circuit 76’’’ when optimizing the first proportion or the second proportion; regarding Walz fig. 2, one of ordinary skill understands that the amount of heat transferred to the fuel F3 depends on the amount of oil flowing through the heat exchanger 42 and similarly the amount of heat transferred to the air F2 depends on the amount of oil directed to heat exchanger 41; thus controlling the ratio of oil flow with valve 36/136 controls the first amount of heat and the second amount of heat.
The phrase “wherein the range is configured to set a minimum portion of heat to be dissipated to air rather than to fuel, to prevent thermal degradation of stagnant fuel” is an intended result of the method step of operating the heat management system to provide a first amount of heat and a second amount of heat such that the first proportion is in the claimed range. The cited prior art will also reach this result. For example, in the normal course of operation varying the heat dissipated by the at least one fuel-lubricant heat exchanger the two air-lubricant heat exchangers of claim 1 would result in a prevention of thermal degradation of stagnant fuel. This is evidenced by Appukuttan. The same shows (see figs. 3-4) a fuel-lubricant heat exchanger 68 in series with an air-lubricant heat exchanger 78. Appukuttan points out that varying the amount of cooling air provided to the air-lubricant heat exchanger 78 can result in avoiding thermal degradation of stagnant fuel (see par. 64, bottom). Appukuttan states in par. 63 “By providing a valve for moderating the engine cooling airflow provided to the heat exchanger, heating of the fuel to a temperature above the coking temperature prior to combustion in the combustor can be avoided.” Thus using the valve in conditions when stagnant fuel may coke may improve those condition such that coking temperature is not reached. This is consistent with Bosak’s teachings of reducing coking in par. 41. Thus using the valves 80.82 of Schwarz fig. 9 to vary the airflow provided to the air-lubricant heat exchangers prevents fuel degradation of stagnant fuel.
Regarding claims 13-16, The combination of Gaskell in view of Schwarz, Holt, Baralon, Walz and Bosak teach the current invention as claimed and discussed above. The combination teaches (claims 13 and 15) the heat management system to provide the first amount of heat (see thermal loads dissipated as heat energy in par. 44 of Schwarz regarding the claim 1 analysis above regarding the least one air-lubricant heat exchanger 92,106 in Schwarz fig. 9) and the second amount of heat (see par. 12 of Schwarz regarding the fuel-lubricant heat exchanger 146 of Schwarz fig. 10 discussed in the claim 1 analysis above) such that there is a proportion of heat (i.e. the first proportion as discussed in the claim 1 analysis above) generated by the gearbox 32 (see Schwarz fig. 9) and the turbomachinery 64 (see Schwarz fig. 9) and dissipated to air; and NH is the core shaft speed expressed as proportion of the core shaft maximum take-off speed and is in the range of from 0.65 to 1 (Gaskell core shaft has a running speed in the range of 1500 rpm to 6200 rpm, see pars. 21, 118 and 165, and thus Gaskell operates at the instant range of .65(6200) to 1(6200) and thus one of ordinary skill understands that the heat management system of the combination is used to dissipate heat at the instant rpm); wherein (claims 14 and 16) NH is in the range of from 0.65 to 085 (see above).
Regarding claims 13 and 15, these instant claims recite:
the proportion of heat
(claim 13) is greater than A-NH + B, and less than the lower of 1 and C-NH + D, wherein A is equal to -1.15, B is equal to, or greater than, 1.48, C is equal to - 1.84, D is in the range of from 2.18 to 2.30; and
(claim 15) is greater than A-NH + B, and less than the lower of 1 and E- (NH - 1) + F, wherein A is equal to -1.15, B is equal to, or greater than, 1.48, E is in the range of from -1.16 to -3; F is equal to, or greater than, 0.37
The values of the information in the two bullets points above are summarized in the table below (this just distills the requirements of the instant claims and the transformation from the bullet points to the table is not required to be taught by the prior art). The table corresponds with NH = .85 that is within the range the range of NH recited regarding claims 13 and 15.
Table regarding claims 13-16 (the first proportion is used as the “a proportion”)
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Gaskell does not disclose the first proportion
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85%MTO is (claim 13) is greater than A-NH + B, and less than the lower of 1 and C-NH + D (i.e. the first proportion is in the range from 0.50 to 0.74; see Table above); and the first proportion
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85%MTO is (claim 15) is greater than A-NH + B, and less than the lower of 1 and E- (NH - 1) + F (i.e., the first proportion is in the range from 0.50 to 0.82; see Table above).
Regarding claims 13-16, Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak teach all the features of the claimed invention except wherein (claim 13) the proportion is in the range of from 0.50 to 0.74; and (claim 15) the proportion is in the range of from 0.50 to 0.82.
Here, Walz and Bosak teach that the first proportion is result effective across engine operation rpm ranges. The first proportion can be thought of as the comparison of heat transferred from the oil to the at least one fuel-lubricant heat exchanger compared to that transferred by the oil to the at least one first air-lubricant heat exchanger (see instant application publication PGPub US 2024/0110517 A1 at pars. 12-14). As an overall idea, it is preferred to use the at least one fuel-lubricant heat exchanger to dissipate heat from the oil. This preserves energy from the engine system by using waste heat from the oil (see Bosak par. 6) and makes the engine more efficient (see Walz pars. 30 and 35) including improving fuel consumption (see Bosak par. 6). However, Bosak further points out (see par. 41) that too much heating of fuel with a fuel-lubricant heat exchanger results in coking and can damage the fuel equipment. Therefore, (see Walz fig. 2) oil flow through an air-lubricant heat exchanger 41 and a fuel-lubricant heat exchanger 42 can include a bypass circuit 35 that bypasses the air-lubricant heat exchanger 41 using variable bypass valve 36 (also see par. 47 pointing out that the bypass valve can be variable) to vary the respective oil flows through the respective heat exchangers (one of ordinary skill understands that the amount of oil flow corresponds to or relates to the amount of heat; see Pertinent Prior Art section on pages 28-29 in the office action mailed 11/22/2024). However, if too much oil is directed to the at air-lubricant heat exchanger, there will not be enough heat remaining in the oil at the exit of the air-lubricant heat exchanger to properly heat the fuel with the fuel-lubricant heat exchanger when the gas turbine is operating in a cold operating condition as pointed out by Walz in pars. 2, 37 and 38. Finally, Walz points out that proper balance of heat dissipated to air and fuel, across engine operating conditions, is necessary to avoid overdesigned or heavy equipment (see pars. 2 and 39). Bosak adds that in some scenarios it is more efficient for the engine to dissipate more heat to air rather than to fuel because this can keep the oil from degrading at high temperatures that happens when more emphasis it put on keeping energy in the engine system using the fuel-lubricant heat exchanger (see Bosak pars. 5, 12 and 38, bottom, and 48). Bosak accomplishes this by adjusting the speed of lubricant pumps 14,16 to respective heat exchangers 22,24 as shown in figs. 1 and 9. Thus, ratios of the first amount of heat to the second amount of heat control, or have an effect on, the efficiency of operation of a gas turbine, the durability of the fuel equipment, the quality of the lubricant and the capability of a heat management system to provide enough air and fuel to effectively cool the engine oil across engine operating conditions. A recognition in the prior art that a property is affected by the variable is sufficient to find the variable result-effective (MPEP 2144.05 III. C.).
Therefore, an ordinary skilled worker would recognize that the first proportion represented by the percentage of heat from oil transferred to the at least one first air-lubricant heat exchangers compared to that transferred to the at least one fuel-lubricant heat exchanger is a result effective variable. The prior art also teaches that the such a proportion is important at gas turbine engine operating ranges. See Bosak Figure 4 explaining when it can be more efficient, regarding operational scenarios such as idle and takeoff power of the engine, to emphasize average oil temperature and thus there is minimal impact on thrust specific fuel consumption.
Thus, the claimed wherein (claim 13) the proportion (i.e., the first proportion) is in the range of from 0.50 to 0.74 and (claim 15) the proportion (i.e., the first proportion) is in the range of from 0.50 to 0.82. 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., the at least one first air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger are configured to provide the first amount of heat and the second amount of heat, were taught in the prior art by Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak, 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 Gaskell in view of Schwarz, Holt, Baralon, Walz and Bosak’s invention to include wherein the proportion is in the range of from (claim 13) 0.50 to 0.74 and (claim 15) the proportion is in the range of from 0.50 to 0.82 in order to provide an efficient and cost effective heat management system that adapts to engine operating conditions as suggested and taught by Walz and Bosak. 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).
One of ordinary skill is likely to be able to achieve this range for the same reasons as discussed regarding claim 1 above.
Regarding claim 18, Gaskell discloses (see fig. 1) a gas turbine engine 10 for an aircraft (see abstract), the method comprising providing a gas turbine engine 10 comprising:
- an engine core 11 comprising a compressor 14,15, a combustor 16, a turbine 17,19, and a core shaft 26 connecting the turbine 19 to the compressor 14;
- a fan 23 comprising a plurality of fan blades (at 23) and arranged upstream (with respect to stream B) of the engine core 11;
- turbomachinery bearings (see annotated figure above);
- a power gearbox 30 adapted to drive the fan 23 at a lower rotation speed (see par. 10) than the turbine 19; and
- a heat management system configured to provide lubrication and cooling to the turbomachinery bearings (see par. 360 and 367 stating that oil is used for lubricating bearings and thus a lubrication system is provided; one of ordinary skill understands that heat will be transferred to the oil when the oil is at a lower temperature than the bearing for example, and thus the limitation regarding cooling the bearings is met), 85% of the core shaft maximum take-off speed (see par. 118; par. 118 discusses the operating range of the core shaft from 1500 rpm to 6200 rpm, the upper bound 6200 rpm being that speed reached at maximum take-off; therefore the speed of 85% of the core shaft maximum take-off speed would be reached at least during the increase from the lower bound of 1500 rpm to the maximum speed at take-off).
Gaskell does not explicitly disclose the heat management system configured to provide lubrication and cooling to the gearbox, and comprising a pipe assembly adapted to provide a lubricant flow to the gearbox and turbomachinery bearings,
wherein the lubricant flow includes a first loop connected to the turbomachinery bearings and a second loop connected to the gearbox,
the first loop including a first air-lubricant heat exchanger, which is adapted to receive cooling air from a bypass duct to dissipate heat to bypass air, the first loop not including a fuel-lubricant heat exchanger such that heat generated by the turbomachinery bearings is dissipated to the bypass air and not to any fuel-lubricant heat exchanger,
the second loop including a second air-lubricant heat exchanger, which is adapted to receive cooling air from the bypass duct to dissipate heat to the bypass air, at least one fuel-lubricant heat exchanger to dissipate heat to fuel, and a connecting path directly connecting the second air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger, the second air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger in the second loop are arranged in series, and
each of the first and second air-lubricant heat exchangers is a Matrix Air- Cooled Oil Cooler (MACOC), wherein: a first amount of heat is a sum of (i) a total amount of heat generated by the turbomachinery bearings all of which is dissipated to the bypass air via the first air-lubricant heat exchanger and (ii) a portion of heat generated by the gearbox that is dissipated to the bypass air via the second air-lubricant heat exchanger; a second amount of heat is another portion of the heat generated by the gearbox that is dissipated to the fuel via the at least one fuel-lubricant heat exchanger;
the method further comprising:
- operating the heat management system to provide the first amount of heat and the second amount of heat such that a first proportion defined as
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85%MTO at 85% of a core shaft maximum take-off speed is in the range of from 0.25 to 0.70; and
- operating the fan at cruise condition to provide a fan pressure ratio in the range of from 1.35 to 1.43 (more specifically Gaskell is silent the value of the fan pressure ratio).
Schwarz teaches (see figs. 1 and 9) a gas turbine 20 and further teaches a heat management system 180 configured to provide lubrication (via pipes 95 and 109 and lubrication pumps 182,184) and cooling (see discussion of heat exchangers below) to a gearbox 32 (and bearings 64), and comprising a pipe assembly 95,109 adapted to provide a lubricant flow to the gearbox 32 and turbomachinery bearings 64, at least one air-lubricant heat exchanger 92,106 adapted to receive cooling air (cooling air is from bypass gas path 68 in fig. 1; see par. 47 regarding exchanger 92, and see par. 48 regarding exchanger 106) from a bypass duct (duct at 68 in fig. 1) to dissipate a first amount (see thermal loads dissipated as heat energy in par. 44) of heat (in the same manner that applicant claims that all the heat is given to the bypass air; see 112 section above) to a first heat sink (air from air valves 80,82; see pars. 47 and 48),
wherein the first heat sink (air from air valves 80,82; see pars. 47 and 48) is bypass air 68,
wherein a lubricant flow includes a first loop 78’’’ connected to the turbomachinery bearings 64 and a second loop 76 ‘’’ connected to the gearbox 32, the first loop 78’’’ including a first air-lubricant heat exchanger 106, which is adapted to receive cooling air (cooling air is from bypass gas path 68 in fig. 1; see par. 47 regarding exchanger 92, and see par. 48 regarding exchanger 106) from a bypass duct (duct at 68 in fig. 1) to dissipate heat (see thermal loads dissipated as heat energy in par. 44) to bypass air (air from air valves 80,82; see pars. 47 and 48), the first loop 78’’’ not including a fuel-lubricant heat exchanger (see fig. 9 wherein there is no fuel-lubricant heat exchanger) such that heat generated by the turbomachinery bearings 64 is dissipated to the bypass air (air from air valves 80,82; see pars. 47 and 48) and not (there is not a fuel-lubricant heat exchanger in first loop 78’’’ in Schwarz fig. 9 ) to any fuel-lubricant heat exchanger (in the same manner that applicant claims and discloses that not any heat is dissipated to any fuel-lubricant heat exchanger; i.e. there is no fuel-lubricant heat exchanger in first loop 414 in applicant fig. 8; see 112 section above regarding new matter and claim interpretation),
and the second loop 76 ‘’’ including a second air-lubricant heat exchanger 92, which is adapted to receive cooling air (cooling air is from bypass gas path 68 in fig. 1; see par. 47 regarding exchanger 92, and see par. 48 regarding exchanger 106) from the bypass duct (duct at 68 in fig. 1) to dissipate heat to the bypass air (air from air valves 80,82; see pars. 47 and 48).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to provide Gaskell with the gearbox and bearing cooling system of Schwarz in order to facilitate improved lubrication and cooling (see Schwarz pars. 5-6).
Schwarz embodiment of fig. 10 teaches a heat management system 180 with a second loop 76IV (connected to turbomachinery gearbox 32 and in addition to a first loop 78IV) and further teaches at least one fuel-lubricant heat exchanger 146 to dissipate heat (see par. 12) to fuel (fuel of the at least one fuel-lubricant heat exchanger, see pars. 54 and 57; the heat exchanger removes heat from lubricant that is heated by the engine, see par. 49, bottom; such heat is removed from the lubricant by fuel by way of the passages of the at least one fuel-lubricant heat exchanger 146,148, see pars. 54 and 57), and a connecting path (pipe at location 95) directly connecting an air-lubricant heat exchanger 92 and the at least one fuel-lubricant heat exchanger 146, the air-lubricant heat exchanger 92 and the at least one fuel-lubricant heat exchanger 146 in the second loop are arranged in series (see 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 Gaskell in view of Schwarz with at least one fuel-lubricant heat exchanger to dissipate heat to fuel, and a connecting path directly connecting the second air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger, the second air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger in the second loop are arranged in series as taught by Schwarz in order to facilitate further improved lubrication and cooling (see Schwarz pars. 5-6). Including the instant fuel-lubricant heat exchanger permits the heat management system of the combination to keep the energy dissipated by the fuel in the gas turbine system and thus represents an improvement in efficiency compared to waste heat dissipated to air in the bypass duct and then to the environment.
Holt teaches (see fig. 1) a gas turbine and further teaches an air-lubricant heat exchanger 24 is a Matrix Air-Cooled Oil Cooler (MACOC) 24 (see par. 32, top). 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 MACOC type of air-lubricant heat exchanger of Holt for the type (Schwarz teaches the type can be a tube and fin type as an example; see par. 41, top and par. 44, top) of each of the first and second air-lubricant heat exchangers of Gaskell in view of Schwarz for the purpose of substituting one known element for another in order to provide the expected result of providing a structure to exchange heat between air and lubricant.
Baralon teaches (see fig. 1) teaches a fan 23 (of gas turbine 18) is configured to provide at cruise condition (see that the operating point in par. 57 is cruise; see par. 30) a fan pressure ratio in the range of from 1.35 to 1.43 (see par. 57) and thus Baralon teaches a gas turbine with a known value of fan pressure ratio at cruise condition. 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 value of the fan pressure ratio at cruise of Baralon for the fan pressure ratio at cruise of the Gaskell in view of Schwarz and Holt (Gaskell being silent the value fan pressure ratio) for the purpose of substituting one known element for another in order to provide the expected result of a known pressure differential or in other words a known fan pressure ratio (see par. 57 of Baralon) across the fan of the combination to provide propulsive thrust (see par. 115, bottom, of Baralon). This results in the fan of Gaskell in view of Schwarz, Holt and Baralon being configured to provide at cruise condition a fan pressure ratio in the range of from 1.35 to 1.43.
The combination of Gaskell in view of Schwarz, Holt and Baralon teach wherein: a first amount of heat (see thermal loads dissipated as heat energy in Schwarz par. 44) is a sum of (i) a total (see 112 section above regarding interpretation) amount of heat generated by the turbomachinery bearings 64 (see Schwarz fig. 9) all of which (see 112 section above regarding interpretation) is dissipated to the bypass air (air through valve 82) (it is noted that the arrangement of the prior art combination is that same as the instant invention and thus operates in the same functional manner regarding the claimed total amount of heat generated by the bearings as explained in the 112 section above and regarding the instant functional limitations; see MPEP 2112.01) via the first air-lubricant heat exchanger 106 and (ii) a portion of heat (see thermal loads dissipated as heat energy in Schwarz par. 44) generated by the gearbox 32 (see Schwarz fig. 9) that is dissipated to the bypass air (air through valve 80) via the second air-lubricant heat exchanger 92 (see Schwarz fig. 9); a second amount of heat (see thermal loads dissipated as heat energy in Schwarz par. 44) is another portion of the heat generated by the gearbox 32 (see Schwarz fig. 9) that is dissipated to the fuel (fuel shown as horizontal arrows through lubricant heat exchanger 146 in Schwarz fig. 10; heat is dissipated to fuel, e.g., see par. 61, bottom) via the at least one fuel-lubricant heat exchanger 146 (see Schwarz fig. 10); - the heat management system (taught by Gaskell and Schwarz as discussed above) is configured to provide the first amount of heat (from air-lubricant heat exchangers 92,106 in Schwarz fig. 10) and the second amount of heat (from fuel-lubricant heat exchanger 146 in Schwarz fig. 10) such that a first proportion defined as
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85%MTO at 85% of a core shaft maximum take-off speed (85% of the 6200 rpm MTO, see pars. 118 and 165, of Gaskell is 5270 rpm that is just below cruise operating condition of 5400 rpm discussed in par. 164 of Gaskell; the Gaskell core shaft has a running speed in the range of 1500 rpm to 6200 rpm, see par. 21, and thus Gaskell operates at the instant 85% value of 5270 rpm and thus one of ordinary skill understands that the heat management system of the combination is used to dissipate heat at the instant rpm); and (claim 7) such that a second proportion of heat generated by the gearbox and the turbomachinery and dissipated to air defined as
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65%MTO at 65% of a core shaft maximum take-off speed (65% of the 6200 rpm MTO, see pars. 118 and 165, of Gaskell is 4060 rpm; the Gaskell core shaft has a running speed in the range of 1500 rpm to 6200 rpm, see par. 21, and thus Gaskell operates at the instant 65% value of 4060 rpm and thus one of ordinary skill understands that the heat management system of the combination is used to dissipate heat at the instant rpm).
Regarding claim 18, Gaskell in view of Schwarz, Holt and Baralon teach all the features of the claimed invention except wherein the first proportion is in the range of from 0.25 to 0.70.
Here, Walz and Bosak teach that the first proportion is result effective across engine operation rpm ranges. The first proportion can be thought of as the comparison of heat transferred from the oil to the at least one fuel-lubricant heat exchanger compared to that transferred by the oil to the at least one first air-lubricant heat exchanger (see instant application publication PGPub US 2024/0110517 A1 at pars. 12-14). As an overall idea, it is preferred to use the at least one fuel-lubricant heat exchanger to dissipate heat from the oil. This preserves energy from the engine system by using waste heat from the oil (see Bosak par. 6) and makes the engine more efficient (see Walz pars. 30 and 35) including improving fuel consumption (see Bosak par. 6). However, Bosak further points out (see par. 41) that too much heating of fuel with a fuel-lubricant heat exchanger results in coking and can damage the fuel equipment. Therefore, (see Walz fig. 2) oil flow through an air-lubricant heat exchanger 41 and a fuel-lubricant heat exchanger 42 can include a bypass circuit 35 that bypasses the air-lubricant heat exchanger 41 using variable bypass valve 36 (also see par. 47 pointing out that the bypass valve can be variable) to vary the respective oil flows through the respective heat exchangers (one of ordinary skill understands that the amount of oil flow corresponds to or relates to the amount of heat; see Pertinent Prior Art section on pages 28-29 in the office action mailed 11/22/2024). However, if too much oil is directed to the at air-lubricant heat exchanger, there will not be enough heat remaining in the oil at the exit of the air-lubricant heat exchanger to properly heat the fuel with the fuel-lubricant heat exchanger when the gas turbine is operating in a cold operating condition as pointed out by Walz in pars. 2, 37 and 38. Finally, Walz points out that proper balance of heat dissipated to air and fuel, across engine operating conditions, is necessary to avoid overdesigned or heavy equipment (see pars. 2 and 39). Bosak adds that in some scenarios it is more efficient for the engine to dissipate more heat to air rather than to fuel because this can keep the oil from degrading at high temperatures that happens when more emphasis it put on keeping energy in the engine system using the fuel-lubricant heat exchanger (see Bosak pars. 5, 12 and 38, bottom, and 48). Bosak accomplishes this by adjusting the speed of lubricant pumps 14,16 to respective heat exchangers 22,24 as shown in figs. 1 and 9. Thus, ratios of the first amount of heat to the second amount of heat control, or have an effect on, the efficiency of operation of a gas turbine, the durability of the fuel equipment, the quality of the lubricant and the capability of a heat management system to provide enough air and fuel to effectively cool the engine oil across engine operating conditions. A recognition in the prior art that a property is affected by the variable is sufficient to find the variable result-effective (MPEP 2144.05 III. C.).
Therefore, an ordinary skilled worker would recognize that the first proportion represented by the percentage of heat from oil transferred to the at least one first air-lubricant heat exchangers compared to that transferred to the at least one fuel-lubricant heat exchanger is a result effective variable. The prior art also teaches that the such a proportion is important at gas turbine engine operating ranges. See Bosak Figure 4 explaining when it can be more efficient, regarding operational scenarios such as idle and takeoff power of the engine, to emphasize average oil temperature and thus there is minimal impact on thrust specific fuel consumption.
Thus, the claimed wherein the first proportion is in the range of from 0.25 to 0.70 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., the at least one first air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger are configured to provide the first amount of heat and the second amount of heat, were taught in the prior art by Gaskell in view of Schwarz, Holt and Baralon, 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 Gaskell in view of Schwarz, Holt and Baralon’s invention to include wherein the first proportion is in the range of from 0.25 to 0.70 in order to provide an efficient and cost effective heat management system that adapts to engine operating conditions as suggested and taught by Walz and Bosak. 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).
The phrase “wherein the range is configured to set a minimum portion of heat to be dissipated to air rather than to fuel, to prevent thermal degradation of stagnant fuel” is an intended result of the method step of operating the heat management system to provide a first amount of heat and a second amount of heat such that the first proportion is in the claimed range. The cited prior art will also reach this result. For example, in the normal course of operation varying the heat dissipated by the at least one fuel-lubricant heat exchanger the two air-lubricant heat exchangers of claim 18 would result in a prevention of thermal degradation of stagnant fuel. This is evidenced by Appukuttan. The same shows (see figs. 3-4) a fuel-lubricant heat exchanger 68 in series with an air-lubricant heat exchanger 78. Appukuttan points out that varying the amount of cooling air provided to the air-lubricant heat exchanger 78 can result in avoiding thermal degradation of stagnant fuel (see par. 64, bottom). Appukuttan states in par. 63 “By providing a valve for moderating the engine cooling airflow provided to the heat exchanger, heating of the fuel to a temperature above the coking temperature prior to combustion in the combustor can be avoided.” Thus using the valve in conditions when stagnant fuel may coke may improve those condition such that coking temperature is not reached. This is consistent with Bosak’s teachings of reducing coking in par. 41. Thus using the valves 80.82 of Schwarz fig. 9 to vary the airflow provided to the air-lubricant heat exchangers prevents fuel degradation of stagnant fuel.
One of ordinary skill is likely to be able to achieve this range for the same reasons as discussed regarding claim 1 above.
Claim(s) 3-6, 8-12, 19 and 20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak as applied to claim 1 above, and further in view of NPL Aeroengine Safety (ITTMD).
Regarding claims 3, 4 and 19, Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak teach the current invention as claimed and discussed above. Gaskell does not explicitly disclose operating at an environment temperature of (claims 3 and 19) ISA +40°C (i.e., 15°C + 40°C = 65°C; see applicant page 3, bottom) and (claims 4 and 19) ISA +10°C (i.e., 25°C), and the first proportion is in the range of from 0.55 to 0.70 (claims 3 and 19), and (claims 4 and 19) 0.35 to 0.65.
ITTMD teaches a gas turbine (see figure in the middle of page 4) and further teaches operating at an environment temperature of 65°C and 25°C (see figure “Thrust" on page 9; wherein surrounding temperature refers to “atmospheric temperature” in the figure explanation on the same page).
Regarding claims 3 and 4, it would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to provide Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak with operating at an environment temperature of 65°C and 25°C as taught by ITTMD in order to facilitate air transportation in across climates and to ensure the engine can withstand a range of operating conditions. Regarding claim 19, ITTMD provides evidence that aircraft gas turbine engines are configured to operate in the claimed temperature range and thus that the heat management system of the combination is configured to provide the first and second amount of heats at the instant temperature range regarding claim 19.
Regarding claims 3, 4 and 19, Gaskell in view of Schwarz, Holt, Baralon, Walz, Bosak and ITTMD teach all the features of the claimed invention except wherein the first proportion is in the range of from 0.55 to 0.70 (claims 3 and 19), and 0.35 to 0.65 (claims 4 and 19).
Here, Walz and Bosak teach that the first proportion is result effective across engine operation rpm ranges. The first proportion can be thought of as the comparison of heat transferred from the oil to the at least one fuel-lubricant heat exchanger compared to that transferred by the oil to the at least one first air-lubricant heat exchanger (see instant application publication PGPub US 2024/0110517 A1 at pars. 12-14). As an overall idea, it is preferred to use the at least one fuel-lubricant heat exchanger to dissipate heat from the oil. This preserves energy from the engine system by using waste heat from the oil (see Bosak par. 6) and makes the engine more efficient (see Walz pars. 30 and 35) including improving fuel consumption (see Bosak par. 6). However, Bosak further points out (see par. 41) that too much heating of fuel with a fuel-lubricant heat exchanger results in coking and can damage the fuel equipment. Therefore, (see Walz fig. 2) oil flow through an air-lubricant heat exchanger 41 and a fuel-lubricant heat exchanger 42 can include a bypass circuit 35 that bypasses the air-lubricant heat exchanger 41 using variable bypass valve 36 (also see par. 47 pointing out that the bypass valve can be variable) to vary the respective oil flows through the respective heat exchangers (one of ordinary skill understands that the amount of oil flow corresponds to or relates to the amount of heat; see Pertinent Prior Art section on pages 28-29 in the office action mailed 11/22/2024). However, if too much oil is directed to the at air-lubricant heat exchanger, there will not be enough heat remaining in the oil at the exit of the air-lubricant heat exchanger to properly heat the fuel with the fuel-lubricant heat exchanger when the gas turbine is operating in a cold operating condition as pointed out by Walz in pars. 2, 37 and 38. Finally, Walz points out that proper balance of heat dissipated to air and fuel, across engine operating conditions, is necessary to avoid overdesigned or heavy equipment (see pars. 2 and 39). Bosak adds that in some scenarios it is more efficient for the engine to dissipate more heat to air rather than to fuel because this can keep the oil from degrading at high temperatures that happens when more emphasis it put on keeping energy in the engine system using the fuel-lubricant heat exchanger (see Bosak pars. 5, 12 and 38, bottom, and 48). Bosak accomplishes this by adjusting the speed of lubricant pumps 14,16 to respective heat exchangers 22,24 as shown in figs. 1 and 9. Thus, ratios of the first amount of heat to the second amount of heat control, or have an effect on, the efficiency of operation of a gas turbine, the durability of the fuel equipment, the quality of the lubricant and the capability of a heat management system to provide enough air and fuel to effectively cool the engine oil across engine operating conditions. A recognition in the prior art that a property is affected by the variable is sufficient to find the variable result-effective (MPEP 2144.05 III. C.).
Therefore, an ordinary skilled worker would recognize that the first proportion represented by the percentage of heat from oil transferred to the at least one first air-lubricant heat exchangers compared to that transferred to the at least one fuel-lubricant heat exchanger is a result effective variable. The prior art also teaches that the such a proportion is important at gas turbine engine operating ranges. See Bosak Figure 4 explaining when it can be more efficient, regarding operational scenarios such as idle and takeoff power of the engine, to emphasize average oil temperature and thus there is minimal impact on thrust specific fuel consumption.
Thus, the claimed wherein (claims 3 and 19) the first proportion is in the range of from 0.55 to 0.70 and (claims 4 and 19) the first proportion is in the range of from 0.35 to 0.65 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., the at least one first air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger are configured to provide the first amount of heat and the second amount of heat, were taught in the prior art by Gaskell in view of Schwarz, Holt, Baralon, Walz, Bosak and ITTMD, 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 Gaskell in view of Schwarz, Holt, Baralon, Walz, Bosak and ITTMD’s invention to include wherein the (claims 3 and 19) first proportion is in the range of from 0.55 to 0.70 and the (claim 4 and 19) first proportion is in the range of from 0.35 to 0.65 in order to provide an efficient and cost effective heat management system that adapts to engine operating conditions as suggested and taught by Walz and Bosak. 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).
One of ordinary skill is likely to be able to achieve this range for the same reasons as discussed regarding claim 1 above.
Regarding claims 5, 6, 8, 9 and 20, Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak teach the current invention as claimed and discussed above. Gaskell does not disclose (claim 5) a ratio of the first proportion at an environment temperature of ISA + 40°C (i.e., 55°C) to the first proportion at an environment temperature of ISA -69°C (i.e., -54°C) is in the range of from 1.5 to 4.5; (claims 6 and 20) a ratio of the first proportion at an environment temperature of ISA + 40°C (i.e., 55°C) to the first proportion at an environment temperature of ISA +10°C (i.e., 25°C) is in the range of from 1.20 to 1.42; (claim 8) a ratio of the second proportion at an environment temperature of ISA + 40°C (i.e., 55°C) to the second proportion at an environment temperature of ISA -69°C (i.e., -54°C) is in the range of from 1.1 to 2.1; and (claim 9) a ratio of the second proportion at an environment temperature of ISA + 40°C (i.e., 55°C) to the second proportion at an environment temperature of ISA +10°C (i.e., 25°C) is in the range of from 1.10 to 1.25.
ITTMD teaches operating at an environment temperature range of below -50°C to +55°C (see figure “Thrust" on page 9; wherein surrounding temperature refers to “atmospheric temperature” in the figure explanation on the same page; see also page 2, top, page 12, top and middle, and the plots on pages 5 and 9). It is further noted that "[A] prior art reference that discloses a range encompassing a somewhat narrower claimed range is sufficient to establish a prima facie case of obviousness." In re Peterson, 315 F.3d 1325, 1330, 65 USPQ2d 1379, 1382-83 (Fed. Cir. 2003) (MPEP 2144.05 I). Thus, ITTMD teaches an operating range consistent with a range of the endpoint temperatures of -54°C and +55°C.
Regarding claims 5-9, it would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to provide Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak with operating at an environment temperature of ISA + 10°C, ISA + 40°C and ISA -69°C as taught by ITTMD in order to facilitate air transportation in cold and hot climates and to ensure the engine can withstand a range of operating conditions. This results in operating the gas turbine at the instant temperatures to provide the first amount of heat and the second amount of heat that result in the first proportions and the second proportions. Regarding claim 20, ITTMD provides evidence that aircraft gas turbine engines are configured to operate in the claimed temperature range and thus that the heat management system of the combination is configured to provide the first and second amount of heats at the instant temperature range regarding claim 20.
Regarding claims 5, 6, 8, 9 and 20, Gaskell in view of Schwarz, Holt, Baralon, Walz, Bosak and ITTMD teach all the features of the claimed invention except wherein a ratio of the first proportion, or second proportion, at the environment temperature of 55°C to the first proportion, or second proportion, respectively, at the environment temperature of -54°C is in the range of from (claim 5) 1.5 to 4.5, or (claim 8) 1.1 to 2.1, respectively; and a ratio of the first proportion, or second proportion, at the environment temperature of 55°C to the first proportion, or second proportion, respectively, at the environment temperature of 25°C is in the range of from (claims 6 and 20) 1.20 to 1.42, or (claim 9) 1.10 to 1.25.
Here, Walz and Bosak teach that the first proportion is result effective across engine operation rpm ranges. The first proportion can be thought of as the comparison of heat transferred from the oil to the at least one fuel-lubricant heat exchanger compared to that transferred by the oil to the at least one first air-lubricant heat exchanger (see instant application publication PGPub US 2024/0110517 A1 at pars. 12-14). As an overall idea, it is preferred to use the at least one fuel-lubricant heat exchanger to dissipate heat from the oil. This preserves energy from the engine system by using waste heat from the oil (see Bosak par. 6) and makes the engine more efficient (see Walz pars. 30 and 35) including improving fuel consumption (see Bosak par. 6). However, Bosak further points out (see par. 41) that too much heating of fuel with a fuel-lubricant heat exchanger results in coking and can damage the fuel equipment. Therefore, (see Walz fig. 2) oil flow through an air-lubricant heat exchanger 41 and a fuel-lubricant heat exchanger 42 can include a bypass circuit 35 that bypasses the air-lubricant heat exchanger 41 using variable bypass valve 36 (also see par. 47 pointing out that the bypass valve can be variable) to vary the respective oil flows through the respective heat exchangers (one of ordinary skill understands that the amount of oil flow corresponds to or relates to the amount of heat; see Pertinent Prior Art section on pages 28-29 in the office action mailed 11/22/2024). However, if too much oil is directed to the at air-lubricant heat exchanger, there will not be enough heat remaining in the oil at the exit of the air-lubricant heat exchanger to properly heat the fuel with the fuel-lubricant heat exchanger when the gas turbine is operating in a cold operating condition as pointed out by Walz in pars. 2, 37 and 38. Finally, Walz points out that proper balance of heat dissipated to air and fuel, across engine operating conditions, is necessary to avoid overdesigned or heavy equipment (see pars. 2 and 39). Bosak adds that in some scenarios it is more efficient for the engine to dissipate more heat to air rather than to fuel because this can keep the oil from degrading at high temperatures that happens when more emphasis it put on keeping energy in the engine system using the fuel-lubricant heat exchanger (see Bosak pars. 5, 12 and 38, bottom, and 48). Bosak accomplishes this by adjusting the speed of lubricant pumps 14,16 to respective heat exchangers 22,24 as shown in figs. 1 and 9. Thus, ratios of the first amount of heat to the second amount of heat control, or have an effect on, the efficiency of operation of a gas turbine, the durability of the fuel equipment, the quality of the lubricant and the capability of a heat management system to provide enough air and fuel to effectively cool the engine oil across engine operating conditions. A recognition in the prior art that a property is affected by the variable is sufficient to find the variable result-effective (MPEP 2144.05 III. C.).
Therefore, an ordinary skilled worker would recognize that the first proportion represented by the percentage of heat from oil transferred to the at least one first air-lubricant heat exchangers compared to that transferred to the at least one fuel-lubricant heat exchanger is a result effective variable. The prior art also teaches that the such a proportion is important at gas turbine engine operating ranges. See Bosak Figure 4 explaining when it can be more efficient, regarding operational scenarios such as idle and takeoff power of the engine, to emphasize average oil temperature and thus there is minimal impact on thrust specific fuel consumption.
Thus, the claimed the first proportion, or second proportion, at the environment temperature of 55°C to the first proportion, or second proportion, respectively, at the environment temperature of -54°C is in the range of from (claim 5) 1.5 to 4.5, or (claim 8) 1.1 to 2.1, respectively; and a ratio of the first proportion, or second proportion, at the environment temperature of 55°C to the first proportion, or second proportion, respectively, at the environment temperature of 25°C is in the range of from (claims 6 and 20) 1.20 to 1.42, or (claim 9) 1.10 to 1.25 is found to be an obvious optimization of the prior art obtainable by an ordinary skilled worker through routine experimentation. Because each of the first and second proportions are result effective variables, as discussed in the claim 1 and 7 analyses above, it follows that the ratio of for example the first proportion at one operating temperature to the first proportion at another operating temperature is also a result effective variable. This is because at least for the reasons that the instant operating temperatures are standard operating temperatures for aircraft gas turbine engines as pointed out by ITTMD and also because Bosak communicates that the environmental temperature (see fig. 4) affects the oil flow rate provided by pumps 14,16 to the fuel-lubricant heat exchanger 22 and the air-lubricant heat exchanger 24, such flow rates corresponding with or relating to the heat provided to the fuel heat sink and air heat sink of the respective heat exchangers (see Bosak pars. 4 and 52).
Therefore, since the general conditions of the claim, i.e., the at least one first air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger are configured to provide the first amount of heat and the second amount of heat, were taught in the prior art by Gaskell in view of Schwarz, Holt, Baralon, Walz, Bosak and ITTMD, 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 Gaskell in view of Schwarz, Holt, Baralon, Walz, Bosak and ITTMD’s invention to include wherein a ratio of the first proportion, or second proportion, at the environment temperature of 55°C to the first proportion, or second proportion, respectively, at the environment temperature of -54°C is in the range of from (claim 5) 1.5 to 4.5, or (claim 8) 1.1 to 2.1, respectively; and a ratio of the first proportion, or second proportion, at the environment temperature of 55°C to the first proportion, or second proportion, respectively, at the environment temperature of 25°C is in the range of from (claims 6 and 20) 1.20 to 1.42, or (claim 9) 1.10 to 1.25 in order to provide an efficient and cost effective heat management system that adapts to engine operating conditions as suggested and taught by Walz and Bosak. 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).
One of ordinary skill is likely to be able to achieve this range for the same reasons as discussed regarding claim 1 above.
Regarding claims 10 and 11, Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak teach the current invention as claimed and discussed above. Gaskell does not disclose a ratio of the first proportion to the second proportion at an environment temperature of ISA -69°C (i.e., -54°C) is in the range of from 0.30 to 0.55; and a ratio of the first proportion to the second proportion at an environment temperature of ISA +10°C (i.e., 25°C) is in the range of from 0.45 to 0.65.
ITTMD teaches operating at an environment temperature range of below -50°C to +55°C (see figure “Thrust" on page 9; wherein surrounding temperature refers to “atmospheric temperature” in the figure explanation on the same page; see also page 2, top, page 12, top and middle, and the plots on pages 5 and 9). It is further noted that "[A] prior art reference that discloses a range encompassing a somewhat narrower claimed range is sufficient to establish a prima facie case of obviousness." In re Peterson, 315 F.3d 1325, 1330, 65 USPQ2d 1379, 1382-83 (Fed. Cir. 2003) (MPEP 2144.05 I). Thus, ITTMD teaches an operating range consistent with a range of the endpoint temperatures of -54°C and +55°C.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to provide Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak with operating at an environment temperature of ISA -69°C and ISA + 10°C as taught by ITTMD in order to facilitate air transportation in cold and hot climates and to ensure the engine can withstand a range of operating conditions. This results in operating the gas turbine at the instant temperatures to provide the first amount of heat and the second amount of heat.
Regarding claims 10 and 11, Gaskell in view of Schwarz, Holt, Baralon, Walz, Bosak and ITTMD teach all the essential features of the claimed invention except wherein a ratio of the first proportion to the second proportion, at the environment temperatures of (claim 10) -54°C and (claim 11) 25°C is in the range of from (claim 10) 0.30 to 0.55 and (claim 11) 0.45 to 0.65, respectively.
Here, Walz and Bosak teach that the first proportion is result effective across engine operation rpm ranges. The first proportion can be thought of as the comparison of heat transferred from the oil to the at least one fuel-lubricant heat exchanger compared to that transferred by the oil to the at least one first air-lubricant heat exchanger (see instant application publication PGPub US 2024/0110517 A1 at pars. 12-14). As an overall idea, it is preferred to use the at least one fuel-lubricant heat exchanger to dissipate heat from the oil. This preserves energy from the engine system by using waste heat from the oil (see Bosak par. 6) and makes the engine more efficient (see Walz pars. 30 and 35) including improving fuel consumption (see Bosak par. 6). However, Bosak further points out (see par. 41) that too much heating of fuel with a fuel-lubricant heat exchanger results in coking and can damage the fuel equipment. Therefore, (see Walz fig. 2) oil flow through an air-lubricant heat exchanger 41 and a fuel-lubricant heat exchanger 42 can include a bypass circuit 35 that bypasses the air-lubricant heat exchanger 41 using variable bypass valve 36 (also see par. 47 pointing out that the bypass valve can be variable) to vary the respective oil flows through the respective heat exchangers (one of ordinary skill understands that the amount of oil flow corresponds to or relates to the amount of heat; see Pertinent Prior Art section on pages 28-29 in the office action mailed 11/22/2024). However, if too much oil is directed to the at air-lubricant heat exchanger, there will not be enough heat remaining in the oil at the exit of the air-lubricant heat exchanger to properly heat the fuel with the fuel-lubricant heat exchanger when the gas turbine is operating in a cold operating condition as pointed out by Walz in pars. 2, 37 and 38. Finally, Walz points out that proper balance of heat dissipated to air and fuel, across engine operating conditions, is necessary to avoid overdesigned or heavy equipment (see pars. 2 and 39). Bosak adds that in some scenarios it is more efficient for the engine to dissipate more heat to air rather than to fuel because this can keep the oil from degrading at high temperatures that happens when more emphasis it put on keeping energy in the engine system using the fuel-lubricant heat exchanger (see Bosak pars. 5, 12 and 38, bottom, and 48). Bosak accomplishes this by adjusting the speed of lubricant pumps 14,16 to respective heat exchangers 22,24 as shown in figs. 1 and 9. Thus, ratios of the first amount of heat to the second amount of heat control, or have an effect on, the efficiency of operation of a gas turbine, the durability of the fuel equipment, the quality of the lubricant and the capability of a heat management system to provide enough air and fuel to effectively cool the engine oil across engine operating conditions. A recognition in the prior art that a property is affected by the variable is sufficient to find the variable result-effective (MPEP 2144.05 III. C.).
Therefore, an ordinary skilled worker would recognize that the first proportion represented by the percentage of heat from oil transferred to the at least one first air-lubricant heat exchangers compared to that transferred to the at least one fuel-lubricant heat exchanger is a result effective variable. The prior art also teaches that the such a proportion is important at gas turbine engine operating ranges. See Bosak Figure 4 explaining when it can be more efficient, regarding operational scenarios such as idle and takeoff power of the engine, to emphasize average oil temperature and thus there is minimal impact on thrust specific fuel consumption.
Thus, the claimed (claim 10) the first proportion to the second proportion at an environment temperature of ISA -69°C (i.e., -54°C) is in the range of from 0.30 to 0.55; and (claim 11) a ratio of the first proportion to the second proportion at an environment temperature of ISA +10°C (i.e., 25°C) is in the range of from 0.45 to 0.65 is found to be an obvious optimization of the prior art obtainable by an ordinary skilled worker through routine experimentation. Because each of the first and second proportions are result effective variables, as discussed in the claim 1 and 7 analyses above, it follows that the ratio of for example the first proportion to the second proportion is also a result effective variable. This is because at least for the reasons that the instant operating temperatures are standard operating temperatures for aircraft gas turbine engines as pointed out by ITTMD and also because the first and second heats are related to operating at different engine operating settings (i.e., 65%MTO and 85%MTO) as pointed out by Bosak in table 4 as previously discussed.
Therefore, since the general conditions of the claim, i.e., the at least one first air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger are configured to provide the first amount of heat and the second amount of heat, were taught in the prior art by Gaskell in view of Schwarz, Holt, Baralon, Walz, Bosak and ITTMD, 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 Gaskell in view of Schwarz, Holt, Baralon, Walz, Bosak and ITTMD’s invention to include wherein (claim 10) a ratio of the first proportion to the second proportion at an environment temperature of ISA -69°C (i.e., -54°C) is in the range of from 0.30 to 0.55; and (claim 11) a ratio of the first proportion to the second proportion at an environment temperature of ISA +10°C (i.e., 25°C) is in the range of from 0.45 to 0.65 in order to provide an efficient and cost effective heat management system that adapts to engine operating conditions as suggested and taught by Walz and Bosak. 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).
One of ordinary skill is likely to be able to achieve this range for the same reasons as discussed regarding claim 1 above.
Regarding claim 12, Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak teach the current invention as claimed and discussed above. Gaskell does not disclose operating at an environment temperature of ISA +10°C (i.e., 25°C) and ISA -69°C (i.e., -54°C), and the first proportion is in the range of from 0.60 to 0.95, and 0.40 to 0.75, respectively.
ITTMD teaches operating at an environment temperature of 25°C (see figure “Thrust" on page 9; wherein surrounding temperature refers to “atmospheric temperature” in the figure explanation on the same page). ITTMD teaches operating at an environment temperature range of below -50°C to +55°C (see figure “Thrust" on page 9; wherein surrounding temperature refers to “atmospheric temperature” in the figure explanation on the same page; see also page 2, top, page 12, top and middle, and the plots on pages 5 and 9). It is further noted that "[A] prior art reference that discloses a range encompassing a somewhat narrower claimed range is sufficient to establish a prima facie case of obviousness." In re Peterson, 315 F.3d 1325, 1330, 65 USPQ2d 1379, 1382-83 (Fed. Cir. 2003) (MPEP 2144.05 I). Thus, ITTMD teaches an operating range consistent with a range of the endpoint temperatures of -54°C and +55°C.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to provide Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak with operating at an environment temperature of 25°C and -54°C as taught by ITTMD in order to facilitate air transportation in across climates and to ensure the engine can withstand a range of operating conditions.
Regarding claim 12, Gaskell in view of Schwarz, Holt, Baralon, Walz, Bosak and ITTMD teach all the essential features of the claimed invention except wherein the second proportion is in the range of from 0.60 to 0.95, and 0.40 to 0.75.
Here, Walz and Bosak teach that the first proportion is result effective across engine operation rpm ranges. The first proportion can be thought of as the comparison of heat transferred from the oil to the at least one fuel-lubricant heat exchanger compared to that transferred by the oil to the at least one first air-lubricant heat exchanger (see instant application publication PGPub US 2024/0110517 A1 at pars. 12-14). As an overall idea, it is preferred to use the at least one fuel-lubricant heat exchanger to dissipate heat from the oil. This preserves energy from the engine system by using waste heat from the oil (see Bosak par. 6) and makes the engine more efficient (see Walz pars. 30 and 35) including improving fuel consumption (see Bosak par. 6). However, Bosak further points out (see par. 41) that too much heating of fuel with a fuel-lubricant heat exchanger results in coking and can damage the fuel equipment. Therefore, (see Walz fig. 2) oil flow through an air-lubricant heat exchanger 41 and a fuel-lubricant heat exchanger 42 can include a bypass circuit 35 that bypasses the air-lubricant heat exchanger 41 using variable bypass valve 36 (also see par. 47 pointing out that the bypass valve can be variable) to vary the respective oil flows through the respective heat exchangers (one of ordinary skill understands that the amount of oil flow corresponds to or relates to the amount of heat; see Pertinent Prior Art section on pages 28-29 in the office action mailed 11/22/2024). However, if too much oil is directed to the at air-lubricant heat exchanger, there will not be enough heat remaining in the oil at the exit of the air-lubricant heat exchanger to properly heat the fuel with the fuel-lubricant heat exchanger when the gas turbine is operating in a cold operating condition as pointed out by Walz in pars. 2, 37 and 38. Finally, Walz points out that proper balance of heat dissipated to air and fuel, across engine operating conditions, is necessary to avoid overdesigned or heavy equipment (see pars. 2 and 39). Bosak adds that in some scenarios it is more efficient for the engine to dissipate more heat to air rather than to fuel because this can keep the oil from degrading at high temperatures that happens when more emphasis it put on keeping energy in the engine system using the fuel-lubricant heat exchanger (see Bosak pars. 5, 12 and 38, bottom, and 48). Bosak accomplishes this by adjusting the speed of lubricant pumps 14,16 to respective heat exchangers 22,24 as shown in figs. 1 and 9. Thus, ratios of the first amount of heat to the second amount of heat control, or have an effect on, the efficiency of operation of a gas turbine, the durability of the fuel equipment, the quality of the lubricant and the capability of a heat management system to provide enough air and fuel to effectively cool the engine oil across engine operating conditions. A recognition in the prior art that a property is affected by the variable is sufficient to find the variable result-effective (MPEP 2144.05 III. C.).
Therefore, an ordinary skilled worker would recognize that the first proportion represented by the percentage of heat from oil transferred to the at least one first air-lubricant heat exchangers compared to that transferred to the at least one fuel-lubricant heat exchanger is a result effective variable. The prior art also teaches that the such a proportion is important at gas turbine engine operating ranges. See Bosak Figure 4 explaining when it can be more efficient, regarding operational scenarios such as idle and takeoff power of the engine, to emphasize average oil temperature and thus there is minimal impact on thrust specific fuel consumption.
Thus, the claimed wherein the second proportion is in the range of from 0.60 to 0.95, and 0.40 to 0.75 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., the at least one first air-lubricant heat exchanger and the at least one fuel-lubricant heat exchanger are configured to provide the first amount of heat and the second amount of heat, were taught in the prior art by Gaskell in view of Schwarz, Holt, Baralon, Walz, Bosak and ITTMD, 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 Gaskell in view of Schwarz, Holt, Baralon, Walz, Bosak and ITTMD’s invention to include wherein the second proportion is in the range of from 0.60 to 0.95, and 0.40 to 0.75 in order to provide an efficient and cost effective heat management system that adapts to engine operating conditions as suggested and taught by Walz and Bosak. 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).
One of ordinary skill is likely to be able to achieve this range for the same reasons as discussed regarding claim 1 above.
Claim(s) 17 is/are rejected under 35 U.S.C. 103 as being unpatentable over Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak as applied to claim 1 above, and further in view of Pub. No. US 2012/0285402 A1 (Foster).
Regarding claim 17, Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak teach the current invention as claimed and discussed above. Gaskell does not explicitly disclose a flow restriction valve arranged downstream of the air-lubricant heat exchanger, the method including operating the flow restriction valve to vary a mass flow rate of the cooling air across the air-lubricant heat exchanger, thereby varying the first amount of heat.
Foster teaches a gas turbine 110 (see fig. 1) heat management system (see par. 99) and further teaches (see fig. 4) a flow restriction valve 26 arranged downstream of an air-lubricant heat exchanger 52, the method including operating the flow restriction valve 26 to vary a mass flow rate (see pars. 72, 77 and 83) the amount of air of the cooling air across the air-lubricant heat exchanger 26, thereby varying an amount of heat (see par. 77).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to provide Gaskell in view of Schwarz, Holt, Baralon, Walz, and Bosak with a flow restriction valve arranged downstream of the air-lubricant heat exchanger, the method including operating the flow restriction valve to vary a mass flow rate of the cooling air across the air-lubricant heat exchanger, thereby varying the first amount of heat as taught by Foster in order to facilitate maintaining the oil quality at an acceptable level regarding for example different oil brands and level of contaminants (see Foster pars. 103 and 106).
Response to Arguments
Applicant's arguments filed 03/16/2026 have been fully considered but they are not persuasive.
Applicant argues against the claim 1 rejection in the non-final office action mailed 12/15/2026 because six references were used. In response to applicant's argument that the examiner has combined an excessive number of references, reliance on a large number of references in a rejection does not, without more, weigh against the obviousness of the claimed invention. See In re Gorman, 933 F.2d 982, 18 USPQ2d 1885 (Fed. Cir. 1991). Of the six references it is noted that Walz and Bosak are merely used to show that one of ordinary skill would understand the percentage of heat from oil transferred to the first and second air-lubricant heat exchangers compared to that transferred to the at least one fuel-lubricant heat exchanger is a result effective variable. In other words that it would have been obvious to one of ordinary skill in the art before the effective filing date of the current invention to arrive at the claim 1 range by a process of routine optimization.
Applicant argues that the references are not in the same field of endeavor. In response all six references are from the gas turbine field of endeavor. For example see gas turbine 10 in Gaskell fig. 1, gas turbine 20 in Schwarz fig. 1, gas turbine 10 in Holt fig. 1, gas turbine 18 in Baralon fig. 1, gas turbine 10 in Walz fig. 1 and “gas turbine” at Bosak par. 31. Thus the instant references are all in the same field of endeavor.
Applicant argues MPEP section 707.07(g) has not been complied with. The instant section requires the office action to “reject each claim on all valid grounds available, avoiding, however, undue multiplication of references”. For example rejections are made under 35 USC 112 and 103 in this office action and thus the valid grounds of rejection are covered. In addition there were not multiple rejections of the same claims (see MPEP 904.03) with different references and thus applicant argument is not persuasive in the non-final office action.
In response to applicant's arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986). For example, applicant attacks Bosak writing many paragraphs but applicant provides no reasoning against the purpose of Bosak such purpose being to show applicant’s claimed range of the first proportion is a result effective variable. As shown below applicant’s arguments actually support Bosak’s inclusion in the 103 section above especially because applicant fig. 7 published in 2024 is almost identical to Bosak’s fig. 1 as the figures pertain to the path of lubricant through a fuel-lubricant heat exchanger and an air-lubricant heat exchanger. Applicant cites par. 41 that merely points out that increasing the oil flow rate through the fuel-lubricant heat exchanger (i.e., FOHE in Bosak’s nomenclature) raises the fuel temperature but that too much rise in fuel temperature leads to thermal degradation of the fuel in the form of coking. The coking occurs because the higher oil flow rates provide a higher amount of heat to the fuel and thus applicant is stating oil flow rates correspond with an amount of heat transfer. Applicant states “minimum heat transfer capacitance is dictated by the oil side”. In response applicant has provided no evidence of this and it does not appear that one of ordinary skill would come to the same conclusion regarding Bosak. One of ordinary skill in contrast would understand that a central concept of Bosak is to vary the flow rates of respective fuel-lubricant heat exchanger and air-lubricant heat exchanger for example shown in fig. 1 via respective lubricant pumps 14,16 in order to improve specific fuel consumption (SFC) and oil/engine component quality. For example Bosak points out that heat rejection via the fuel-lubricant heat exchanger is preferred over heat rejection over air-lubricant heat exchangers because heat from the oil is used to heat the fuel that improves fuel economy (heat from lubricants heating air is lost to the environment and does not stay in the gas turbine system). However Bosak also points out that too much heating of the fuel causes thermal degradation of the fuel such as coking as discussed above and thus some of the engine heat carried by the lubricant must be rejected to air to avoid the thermal degradation of the fuel. Heat rejection to air on the other hand can result in lower lubricant temperatures that preserve oil life and leads to less component degradation even though fuel is heated to less than its maximum temperature and there is some penalty to SFC (see Bosak pars. 5, 12 and 38, bottom, and 48). Bosak teaches varying the speeds of pumps 14 and 16 that set the oil flow rate to the fuel-lubricant and air-lubricant heat exchangers can balance the benefits of lower oil temperatures with the benefits of specific fuel consumption afforded by higher fuel temperatures. Thus the maximum heat rejection of Bosak is guided by the operation of the fuel pumps 14,16 rather than just the operation of the air-lubricant heat exchanger as stated by applicant in page 12 middle. Applicant has not shown why Bosak is not relevant to showing the claimed ranges of claimed first proportion is not a result effective variable and thus Bosak remains cited in the 103 section above.
Applicant states “The design of the heat exchanger, in particular the AOHE and its physical integration on the engine to limit the impact on air side pressure losses which could ultimately impact SFC (Specific Fuel Consumption), results in most cases in having the air side being the minimum heat transfer capacitance and hence being the limiting parameter to the thermal energy available to transfer.” This appears to have no relevance to Bosak as Bosak does not discuss heat exchanger integration nor pressure losses. Pressure losses regarding an air-lubricant heat exchanger can be due to loss of air pressure in the fan duct because air is channeled to the heat exchanger and thus there is a thrust penalty, or oil flow leakage that can affect oil flow rates. Applicant has not made clear how this is relevant to Bosak’s beneficial balancing of heat dissipated between the air-lubricant heat exchanger and the fuel-lubricant heat exchanger.
Applicant argues a hypothetical scenario of mass flow rates of oil and air but is silent mass flow rates of fuel and as best understood makes a conclusory statement about fuel-lubricant heat exchanger being control in gas turbines. As mentioned before Bosak balances the lubricant flow between the air-lubricant heat exchanger 24 and fuel-lubricant heat exchanger 22 by way of lubricant pumps 14 and 16 respectively to ensure (1) the fuel temperature is reasonably high to accommodate good SFC without fuel thermal degradation and (2) the oil temperature is reasonably low such that the lubricant does not degrade and damage the engine components the lubricant is cooling. Thus the varying of a first heat dissipated to the air oil heat exchanger 24 and a second heat dissipated to the fuel oil heat exchanger 22 has an effect on specific fuel consumption and on oil quality and gas turbine component durability. This points to applicant’s claimed range of 0.25 to 0.70 as being result effective under MPEP 2144.05 and thus it would have been obvious to arrive at the claimed range by a process of routine optimization.
Applicant argues proportionality of oil mass flow rate and heat rejection is a narrow exception. In response this appears to be directly contradicted by applicant disclosure. For example par. 20 of PGPub 2021/0172375 A1 states: “increasing (or decreasing) the lubricant mass flow rate to the air-lubricant heat exchanger(s) … would increase (or decrease) the first amount of heat dissipated to the first sink” and similarly “increasing (or decreasing) the lubricant mass flow rate to the fuel-lubricant heat exchanger(s) would increase (or decrease) the second amount of heat dissipated to the second sink. This is consistent with Tumelty (Pub. No. 20050081507 A1) cited on page 28 of the office action mailed 11/22/2024 stating: “The amount of heat rejected by the oil system is proportional to the amount of oil that flows to the lubricated components 18” wherein the heat is rejected with fuel-lubricant heat exchanger 16 in fig. 3. Thus the amount of oil flow can correspond with an amount of heat rejected.
Applicant states adding the limitation “in series” regarding describing the claimed second loop “would not allow the Examiner to derive any heat ratios from Bosak” and makes Bosak not applicable. In response it is not clear what derivations applicant is referring to. The range of 0.25 to 0.70 of the first proportion
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85%MTO at 85% of a core shaft maximum take-off speed was treated as a result effective variable and Walz and Bosak were used to explain that numerical ranges of such ratios of heats are result effective. Bosak is applicable because Bosak varies first and second amounts of heat (i.e. heats dissipated by the air oil heat exchanger and heat dissipated by the fuel oil heat exchanger to arrive at good SFC and reliable lubricant and engine components. Bosak’s applicability to claim 1 for example is further supported by applicant disclosure that communicates that the instant claimed range pertains to both figs. 7 and 8 (see pars. 454 and 463-464 stating the claimed range 0.25 to 0.70 is applies to both figs. 7 and 8). Fig. 7 is very similar to Bosak fig. 1 and thus Bosak’s result effective analysis is relevant to applicant’s claimed range. For example Bosak fig. 1 shows a lubricant path of heat load 20, tank 18, air-lubricant heat exchanger 24/fuel-lubricant heat exchanger 22 in parallel, and heat load 20 (wherein one of ordinary skill in the art would understand Bosak’s heat load is concerned with a power gearbox as pointed out in par. 3; for example Bosak seeks to improve on the geared turbofan thermal management system discussed in par. 10; Bosak further states in par. 31 that its teachings are applicable to any turbofan engine). Similarly applicant fig. 7 shows heat load 301, tank 120, air-lubricant heat exchanger 104/fuel-lubricant heat exchanger 105 in parallel, and heat load 301. Thus one or ordinary skill in the art would understand that Bosak’s configuration of heat exchangers is applicable to varying the first and second amount of heats of Gaskell in view of Schwarz, Holt and Baralon cited in the 103 section above regarding claim 1.
Applicant argues against Walz pars. 2 and 39 because applicant believes they are not related to the claimed range being result effective. Par. 2 states “Providing oil cooling that can adapt to the operating conditions of the aircraft engine can affect cost, size, weight and complexity of a cooling system. Improvement is desirable.” One example of adapting to the operating conditions of the aircraft is discussed in Walz par. 37. For example in cold conditions lubricant may bypass the air-lubricant heat exchanger 41 in fig. 2 so that more heat is available to heat the fuel via the fuel-lubricant heat exchanger 42. This saves money and space because another structure is not needed to heat the fuel in low temperature conditions. “The bypass valve 36 may be in the open configuration during relatively cold operating conditions of the gas turbine engine 10 to preserve heat from the oil to be preferably transferred to the fuel instead of the air” (see par. 38, bottom). Par. 39 points out that varying the heat dissipated to air versus that dissipated to fuel affects the cost of the engine and aircraft. For example in order to adapt to operating conditions the bypass valve 36 opening amount is varied. A flow restrictor 37 may be added to better adapt to the operating conditions and thus obviating the need for a larger bypass conduit 35 to accommodate suppling more lubricant to the fuel-lubricant heat exchanger 42 when additional fuel heating is necessary (and such the cost of a larger bypass is not needed). Thus the property of cost and equipment compactness is affected by varying the amount of the first and second heats and therefore the claimed range is result effective.
Applicant argues the cited prior art does not discuss thermal degradation of stagnant fuel. In response newly evidentiary art Appukuttan (US 2014/0090395) provided in the 103 section above communicates that this problem has been known in the art since 2014 and Appukuttan’s solution to such problem is to vary the ratio of first and second heats as explained in the 103 section. For example additional cooing air is provided to the air-lubricant heat exchanger 78 in Appukuttan figs. 3-4 via valve 84 in order to prevent coking thermal degradation of stagnant fuel (see pars. 63-64).
Applicant argues Bosak does not address SFC with first and second heats. In response one of the purposes of Bosak is to improve SFC as discussed above. Applicant argues Bosak does not discuss thermal degradation. In response, prevention of fuel coking is discussed in par. 41 that applicant cites above.
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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