Detailed Action
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Drawings
Applicant’s argument filed 12/22/2025 overcome the 112a and 112b rejections related to terms “the second fuel pressure” in the fuel conduit downstream of the fuel metering valve” and “the pressure differential between the second fuel pressure and a pressure of the combustor” issued in Office Action mailed 09/22/2025 and therefore, overcome the drawing objection applied in Office Action mailed 09/22/2025. The drawings filed 06/09/2023 are accepted.
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 21-29 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.
Regarding claim 21 and its dependents, recitation “determine a flow over area ratio (Wf/Afmv) based on one or more of the first fuel pressure, the second fuel pressure, the pressure differential, and the state of the gaseous fuel flow” contains limitation that the specification does not provide an adequate written description of the computer and algorithm to demonstrate to one of ordinary skill in the art that the inventor possessed the claimed method step.
Specifically, according to specification, Fig. 3 and from p. 15, l. 16 to p. 16, l. 22, the specification merely discloses a rate Wf/Afmv is calculate as function of P1, T1, when the gaseous fuel flow is sonic, or as function of P1, P2, DP, and T1, when the gaseous fuel flow is subsonic. Moreover, from p. 5, l. 20 to p. 6, l. 5, the specification merely states that calculating a sonic/subsonic flow rate as a function of the first fuel pressure and the first fuel temperature/a function of the first fuel pressure, the first fuel temperature, a second fuel pressure, and a pressure differential.
It is noted, “Similarly, original claims may lack written description when the claims define the invention in functional language specifying a desired result but the specification does not sufficiently describe how the function is performed or the result is achieved. For software, this can occur when the algorithm or steps/procedure for performing the computer function are not explained at all or are not explained in sufficient detail (simply restating the function recited in the claim is not necessarily sufficient). In other words, the algorithm or steps/procedure taken to perform the function must be described with sufficient detail so that one of ordinary skill in the art would understand how the inventor intended the function to be performed”, and it is further noted, “When examining computer-implemented functional claims, examiners should determine whether the specification discloses the computer and the algorithm (e.g., the necessary steps and/or flowcharts) that perform the claimed function in sufficient detail such that one of ordinary skill in the art can reasonably conclude that the inventor possessed the claimed subject matter at the time of filing. An algorithm is defined, for example, as "a finite sequence of steps for solving a logical or mathematical problem or performing a task." Microsoft Computer Dictionary (5th ed., 2002). Applicant may "express that algorithm in any understandable terms including as a mathematical formula, in prose, or as a flow chart, or in any other manner that provides sufficient structure." Finisar Corp. v. DirecTV Grp., Inc., 523 F.3d 1323, 1340, 86 USPQ2d 1609, 1623 (Fed. Cir. 2008) (internal citation omitted). It is not enough that one skilled in the art could write a program to achieve the claimed function because the specification must explain how the inventor intends to achieve the claimed function to satisfy the written description requirement. See, e.g., Vasudevan Software, Inc. v. MicroStrategy, Inc., 782 F.3d 671, 681-683, 114 USPQ2d 1349, 1356, 1357 (Fed. Cir. 2015) (reversing and remanding the district court’s grant of summary judgment of invalidity for lack of adequate written description where there were genuine issues of material fact regarding "whether the specification show[ed] possession by the inventor of how accessing disparate databases is achieved")”, MPEP 2161.01(I).
In this case, the specification does not provide sufficient details of how the claimed flow over area ratio Wf/Afmv is determined/calculated, i.e., what function/mathematical formula is used to determine/calculate the claimed flow over area ratio.
The same lacking adequate written description rejection is also applied to the limitation, “determine the flow over area ratio (Wf/Afmv) based on one or more of the first fuel pressure, the second fuel pressure, the pressure differential, the state of the gaseous fuel flow, and the fuel temperature”, of claim 22 and its dependents.
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 21-29 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.
Regarding claim 21 and its dependents, even in light of specification, the recitation “determine a flow over area ratio (Wf/Afmy) based on one or more of the first fuel pressure, the second fuel pressure, the pressure differential, and the state of the gaseous fuel flow; determine an effective area (Afmy) of the fuel metering valve based on the position of the fuel metering valve; and determine a fuel flow rate (Wf) of the gaseous fuel flow to obtain the desired power output of the aircraft engine by multiplying the flow over area ratio (Wf/Afmy) by the effective area (Afmy)” is indefinite because:
i) from p. 15, l. 16 to p. 16, l. 22 and Fig. 3, specification merely states that a sonic flow rate Wf/Afmy is calculated as a function of the first fuel pressure P1 and fuel temperature T1, where fmv effective area Afmv is calculated by reading the position sensor feedback signal 149, and required fuel flow is then calculated using Wf = (Wf/Afmv) X Afmv, and a subsonic flow rate Wf/Afmy is calculated as a function of the first fuel pressure P1, the second fuel pressure P2, the delta pressure, and the fuel temperature T1, where fmv effective area Afmv is calculated by reading the position sensor feedback signal 149, and required fuel flow is then calculated using Wf = (Wf/Afmv) X Afmv, however, the specification does not define a) reference character(s) Wf in each of the equations, i.e., Wf/Afmy and Wf = (Wf/Afmv) X Afmv, refers to what parameter(s), and b) reference character(s) Afmv in each of the equations, i.e., Wf/Afmy and Wf = (Wf/Afmv) X Afmv, refers to what parameter(s);
ii) similarly, the recitation of claim 21, does not define a) reference character(s) Wf in each of the equations, i.e., Wf/Afmy and Wf = (Wf/Afmv) X Afmv, refers to what parameter(s), and b) reference character(s) Afmv in each of the equations, i.e., Wf/Afmy and Wf = (Wf/Afmv) X Afmv, refers to what parameter(s);
iii) it is noted that the equation used to determine the required fuel flow rate as disclosed and as claimed, Wf = (Wf/Afmv) X Afmv, is ended up as Wf = Wf, thus, it is unclear a) the reference character Wf in each of the claimed flow over area ratio (Wf/Afmy), the claimed fuel flow rate (Wf) obtains the desired power output, and the claimed equation (Wf/Afmv) X Afmv, refers to what parameter(s), b) the reference character Afmy in each of the claimed flow over area ratio (Wf/Afmy) and the claimed equation (Wf/Afmv) X Afmv, refers to what parameter(s), and c) it is unclear whether the reference character Afmy in each of the claimed flow over area ratio (Wf/Afmy) and the claimed equation (Wf/Afmv) X Afmv, refers to the previously claimed effective area (Afmv) determined based on the position of the fuel metering valve.
Therefore, due to ambiguities related to the reference characters Wf and Afmv, the claim language of claim 21 is impossible for interpretation.
The same rejection is also applied to term “the flow over area ratio (Wf/Afmv)” in claim 22 and its dependents.
Regarding claim 24 and its dependent, recitation “the sensors include a third pressure sensor operable to generate a signal indicative of the third pressure” is indefinite because term “the third pressure” lacks antecedent basis and it is unclear whether “the third pressure” refers to i) any pressure of the previously claimed pressures, i.e., the first fuel pressure, the second fuel pressure, the pressure differential, or the pressure of the combustor; or ii) a different one, and it is further unclear whether “the third pressure sensor” refers to i) any sensor of the previously claimed sensors; or ii) a different one.
Relevant Arts
With reference to the rejection(s) under 35 USC 112b above, the claim 21 could not be understood, but to the extent that it could be understood, a search was performed and the following references were found to be relevant:
KAMATH 20150321767 teaches a fuel system (the fuel system as shown in Figs. 2 and 8) for an aircraft engine (5), comprising:
a fuel conduit (the section of the fuel conduit downstream from the FFC 504 in Fig. 8) fluidly connecting a source of a gaseous fuel (the part of the fuel system in Fig. 8 that upstream from the FFC 504) to a combustor (where fuel nozzles are, see Fig. 8);
a fuel metering valve the GMV 550 in Fig. 8 and [0089]) connected to the fuel conduit (annotated Figs. 2 and 8);
sensors operable to generate signals indicative of a position of the fuel metering valve (generated by LVDT 564, [0090]), a first fuel pressure (generated by GP1, [0090]) in the fuel conduit (annotated Figs. 2 and 8) upstream of the fuel metering valve (the GMV 550 in Fig. 8), a second fuel pressure (generated by GP2, [0090]) in the fuel conduit (annotated Figs. 2 and 8) downstream of the fuel metering valve (the GMV 550 in Fig. 8);
a controller (506 in Fig. 8) operatively connected to the fuel metering valve (the GMV 550 in Fig. 8) and to the sensors (LVDT 564, pressure sensor GP1, and pressure sensor GP2, see Fig. 8 and [0090]), the controller (506 in Fig. 8) having a processing unit (such processing unit is required for controller 506 to process the data received from the sensors, e.g., engine demand, fuel pressure, fuel temperature, etc., and determine a required fuel flow rate, see [0086-0087]) and a computer-readable medium (such computer-readable medium is required for controller 506 to store algorithms for determining the required fuel flow rate according to the engine demand, fuel pressure, fuel temperature, etc., see [0086-0087]) having instructions stored thereon executable by the processing unit to:
receive a signal indicative of a desired power output (a desired power output of the aircraft engine according to the different flight conditions, which determines a desired fuel split ratio of the gaseous fuel and jet fuel that can be adjusted by the pilot command, see Figs. 7-9 and [0082, 0086-0087, and 0092-0093]) of the aircraft engine (5);
determine a required fuel flow rate of the gaseous fuel flow to obtain the desired power output of the aircraft engine (a required flow rate for the gaseous fuel is determined according to the commanded/desired fuel split ratio of the gaseous fuel and jet fuel, which is variable from 0% to 100%, see Figs. 8-9 and [0082 and 0086-0087]).
McBrien 10317082 teaches a fuel system (see Fig. 2) comprising: a fuel conduit (21) connecting to a combustor (where diffuser 26 is, see Fig. 2); a fuel metering mechanism (15 and 14) connected to the fuel conduit (21), sensors (diffuser pressure sensor 33 and fuel manifold pressure sensor 41) operable to generate signal indicative of a pressure differential between a fuel pressure at a fuel manifold (22) and a pressure of the combustor (at diffuser 26, see col. 10, ll. 46-67); a controller (4) operatively connected to the fuel metering mechanism (15 and 14) and configured to adjust a position of the fuel metering mechanism (15 and 14) according to the signal indicative of the pressure differential between the fuel pressure at the fuel manifold (22) and the pressure of the combustor (at diffuser 26) in order to obtain a desired fuel flow rate (see col. 10, ll. 46-67).
Miller 20050021213 teaches a fuel system for controlling a gaseous fuel comprising: a fuel metering valve (10); sensors operable to generate signals indicative of a position of the fuel metering valve (Fig. 5 and [0057]), a first fuel pressure (a fuel pressure P1 measured by 96) upstream of the fuel metering valve (see Fig. 5 and [0069]), and a second fuel pressure (a fuel pressure P2 measured by 98) downstream of the fuel metering valve (see Fig. 5 and [0069]); a controller (218) operatively connected to the fuel metering valve (10) and to the sensors (see Fig. 5) and configured to:
receive a signal (signal S5 in Fig. 10) indicative of a desired power output of a turbine engine (the desired demand per [0076]);
determine (in the flow measurement equation S2 and the flow control PID loop S6 in Fig. 7, which is performed by the flow measurement algorithm as shown in Fig. 9 and the flow control PID loop algorithm as shown in Fig. 10, also see [0106]), based on the first pressure (P1 is input into the flow measurement algorithm of Fig. 9) and the second pressure (P2 is input into the flow measurement algorithm of Fig. 9), a state of a fuel flow in the fuel conduit (such state is the sonic/subsonic in the flow measurement algorithm of Fig. 9, which is determined by a calculated pressure ratio P2/P1 in S6 of Fig. 9),
determine a real-time effective area of the fuel metering valve based on the position of the fuel metering valve (performed by the convert valve position step S8 or S10 in the flow measurement algorithm in Fig. 9);
determine a real-time fuel flow rate based on the first fuel pressure, the second fuel pressure, and the state of the gaseous fuel flow (performed by the calculate mass flow steps S9 or S11 in the flow measurement algorithm in Fig. 9, also see equations at [0140-0141]);
determine a required fuel flow rate based on the desired power output (performed by read flow demand step S5 in the flow control PID loop algorithm in Fig. 10);
determine a required effective area of the fuel metering valve based on the first fuel pressure, the second fuel pressure, and the state of the gaseous fuel flow (performed by the convert flow demand to CdA steps S8 or S9 in the flow m control PID loop algorithm in Fig. 10, also see equations at [0140-0141]).
Response to Arguments
Applicant's arguments filed 12/22/2025 have been fully considered.
I. With respective to the 112a and 112b rejections issued for terms “the second fuel pressure” in the fuel conduit downstream of the fuel metering valve” and “the pressure differential between the second fuel pressure and a pressure of the combustor” in claim 21, Applicant’s argument is persuasive and thus withdrawn.
II. With respective to the 112a written description rejection issued for limitation “determine a flow over area ratio (W/Amv) based on one or more of the first fuel pressure, the second fuel pressure, the pressure differential, and the state of the gaseous fuel flow” in claim 21 and limitation “determine the flow over area ratio (W/Amv) based on one or more of the first fuel pressure, the second fuel pressure, the pressure differential, the state of the gaseous fuel flow, and the fuel temperature” in claim 22, Applicant’s argument, on p. 6, “Respectfully, these equations are commonly known to the person skilled in the art of compressible fluid dynamics. There is no need to recite, in the instant specification, formulae that would be common knowledge to the person skilled in the art” is not persuasive because:
it is noted, “In several Federal Circuit cases, the patentees argued that the requirement for the disclosure of an algorithm can be avoided if one of ordinary skill in the art is capable of writing the software to convert a general purpose computer to a special purpose computer to perform the claimed function. See, e.g., Blackboard, 574 F.3d at 1385, 91 USPQ2d at 1493; Biomedino, 490 F.3d at 952, 83 USPQ2d at 1123; Atmel Corp., 198 F.3d at 1380, 53 USPQ2d at 1229. Such argument was found to be unpersuasive because the understanding of one skilled in the art does not relieve the patentee of the duty to disclose sufficient structure to support means-plus-function claim terms. Blackboard, 574 F.3d at 1385, 91 USPQ2d at 1493 ("A patentee cannot avoid providing specificity as to structure simply because someone of ordinary skill in the art would be able to devise a means to perform the claimed function."); Atmel Corp., 198 F.3d at 1380, 53 USPQ2d at 1229 ("[C]onsideration of the understanding of one skilled in the art in no way relieves the patentee of adequately disclosing sufficient structure in the specification."). The specification must explicitly disclose the algorithm for performing the claimed function, and simply reciting the claimed function in the specification will not be a sufficient disclosure for an algorithm which, by definition, must contain a sequence of steps. Blackboard, 574 F.3d at 1384, 91 USPQ2d at 1492 (stating that language that simply describes the function to be performed describes an outcome, not a means for achieving that outcome); Microsoft Computer Dictionary, Microsoft Press, 5th edition, 2002; see also Encyclopaedia Britannica, Inc. v. Alpine Elecs., Inc., 355 Fed. App'x 389, 394-95 (Fed. Cir. 2009) (holding that implicit or inherent disclosure of a class of algorithms for performing the claimed functions is not sufficient, and the purported "one-step" algorithm is not an algorithm at all) (unpublished). EON Corp. IP Holdings LLC v. AT&T Mobility LLC, 785 F.3d 616, 623, 114 USPQ2d 1711, 1716 (Fed. Cir. 2015) (disagreeing "that a microprocessor can serve as sufficient structure for a software function if a person of ordinary skill in the art could implement the software function"); Blackboard, 574 F.3d at 1385, 91 USPQ2d at 1492 (explaining that "[t]he fact that an ordinarily skilled artisan might be able to design a program to create an access control list based on the system users’ predetermined roles goes to enablement[,]" whereas "[t]he question before us is whether the specification contains a sufficiently precise description of the ‘corresponding structure’ to satisfy [pre-AIA ] section 112, paragraph 6, not whether a person of skill in the art could devise some means to carry out the recited function")”, MPEP 2181 II(B). In this case, by arguing the equations that used to determine the claimed flow over area ratio are commonly known to the person skilled in the art does not overcome the lacking written description rejection maintained in the current rejection.
II. With respective to the 112b rejection issued for limitation “determine a flow over area ratio (W/Amv) based on one or more of the first fuel pressure, the second fuel pressure, the pressure differential, and the state of the gaseous fuel flow; determine an effective area (Afmv) of the fuel metering valve based on the position of the fuel metering valve; and determine a fuel flow rate (Wf) of the gaseous fuel flow to obtain the desired power output of the aircraft engine by multiplying the flow over area ratio (Wf/Amv) by the effective area (Afmv)” in claim 21, Applicant’s argument, on pp. 6-7, is not persuasive because:
it is noted, “Although the claims are interpreted in light of the specification, limitations from the specification are not read into the claims”, MPEP 2145(VI). In this case, Applicant’s augment, “The flow over area ratio (Wf/Afmv) is not obtained by dividing Wf by Afmv, it is obtained via another computation,
which involves the use of the pressure readings, as recited in claim 21. … In the world of compressible flows, these pressure differences may be used to compute the flow over area ratio. Then, since the effective area Afmv of the valve is known from the position sensor of the valve, the effective area
is multiplied by the flow over area ratio to yield the flow rate of the fuel” is not claimed in claim 21.
Conclusion
THIS ACTION IS MADE FINAL. 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.
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/JINGCHEN LIU/ /GERALD L SUNG/ Primary Examiner, Art Unit 3741 Examiner, Art Unit 3741