Prosecution Insights
Last updated: April 19, 2026
Application No. 18/563,566

METHOD OF DETERMINING A HYDRAULIC TIMING OF A FUEL INJECTOR

Non-Final OA §101§103
Filed
Nov 22, 2023
Examiner
CHARIOUI, MOHAMED
Art Unit
2857
Tech Center
2800 — Semiconductors & Electrical Systems
Assignee
Delphi Technologies Ip Limited
OA Round
1 (Non-Final)
81%
Grant Probability
Favorable
1-2
OA Rounds
3y 4m
To Grant
94%
With Interview

Examiner Intelligence

Grants 81% — above average
81%
Career Allow Rate
556 granted / 686 resolved
+13.0% vs TC avg
Moderate +13% lift
Without
With
+12.7%
Interview Lift
resolved cases with interview
Typical timeline
3y 4m
Avg Prosecution
41 currently pending
Career history
727
Total Applications
across all art units

Statute-Specific Performance

§101
22.6%
-17.4% vs TC avg
§103
30.3%
-9.7% vs TC avg
§102
24.8%
-15.2% vs TC avg
§112
15.7%
-24.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 686 resolved cases

Office Action

§101 §103
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 . 35 USC § 101 The claim 1 has been evaluated under the Alice/Mayo framework in accordance with MPEP § 2106. Although the claim recites mathematical operations, including determining a slope parameter, configuring a pressure drop model, and fitting the model to measured data, the claim as a whole is not directed to an abstract idea. The recited mathematical concepts are integrated into a practical application involving a specific fuel injection system having a fuel rail and pressure sensor, and are applied to measured physical pressure data obtained during an injection event in order to determine a hydraulic timing of a fuel injector. The claimed method therefore applies mathematical analysis to a particular technological environment to improve timing determination in an internal combustion engine. Accordingly, the claim integrates any abstract idea into a practical application and is not directed to a judicial exception under Step 2A, Prong Two. Claims 1-11 are therefore patent-eligible under 35 U.S.C. § 101. Claim Rejections - 35 USC § 101 35 U.S.C. 101 reads as follows: Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title. Claim 11 is rejected under 35 USC § 101 because they are directed to non-statutory subject matter. The descriptions or expressions of the programs are not physical “things.” They are neither computer components nor statutory processes, as they are not “acts” being performed. Such claimed computer programs do not define any structural and functional interrelationships between the computer program and other claimed elements of a computer, which permit the computer program’s functionality to be realized. In contrast, a claimed a non-transitory computer-readable medium encoded with a computer program is a computer element which defines structural and functional interrelationships between the computer program and the rest of the computer which permit the computer program’s functionality to be realized, and is thus statutory. Accordingly, it is important to distinguish claims that define descriptive material per se from claims that define statutory inventions. In order to overcome this rejection, the following language is suggested: “11. (Currently amended) A non-transitory computer readable medium encoded with a computer program product comprising instructions which …” 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. Claims 1, 5, 9 and 11 are rejected under 35 U.S.C. 103 as being unpatentable over Barnes et al. (Pub. No. US 2003/0121501) (hereinafter Barnes) in view of Krogerus et al. (NPL: “Analysis of common rail pressure signal of dual-fuel large industrial engine for identification of injection duration of pilot diesel injectors”) (hereinafter Krogerus). As per claims 1 and 9, Barnes teaches a method of determining a hydraulic timing of a fuel injector in an internal combustion engine, wherein said the injector is coupled to a fuel rail comprising a pressure sensor (see ¶ [0016], i.e., a common rail fuel injection system including a fuel rail equipped with a pressure sensor, pressure sensor 21 sensing pressure in common rail 12, and ¶ [0018], i.e., determining injection timing characteristics, including delay between start of current and start of injection and control signal duration, based on rail pressure). Barnes further discloses a rail pressure predictor model for estimating rail pressure at each injection event using a model equation (see ¶¶ [0019]-[0027]) and using the predicted pressure to determine injection control signal characteristics (see ¶¶ [0033]-[0036]). However, Barnes fails to explicitly teach acquiring fuel pressure data over an acquisition window comprising an injection event of the injector; determining a slope parameter corresponding to a pressure drop caused by to the injection event, or fitting the pressure drop model to measured fuel rail pressure data to derive hydraulic timing. Krogerus, however, discloses acquiring high-resolution rail pressure data during pilot injection events and analyzing the rail pressure signal to identify injection duration (see page 2, Section 2.1 (Experimental setup), describing measurement of common rail pressure during injection evets; and pages 4-5, Section 2.3 (Diagnostics method), describing filtering of rail pressure signal and calculation of derivative of the pressure signal to identify the pressure drop caused by injection. Krogerus further discloses identifying injection start and end timing based on analysis of the rail pressure drop transient (see page 6-9, Section 3, Results and discussion and Section 4 (Conclusions)), thereby deriving injection duration (hydraulic timing) from the pressure drop behavior. It would have been obvious to one having ordinary skill in the art before the effective filling date of the claimed invention to modify the rail-pressure-based injection timing control system of Barnes to incorporate the rail pressure drop analysis technique of Krogerus because both references are directed to improving injection timing accuracy in common rail fuel injection systems using rail pressure behavior, thereby enabling direct derivation of validation of hydraulic timing from measured rail pressure data in addition to predictive rail pressure modeling. Accordingly, the combination teaches acquiring rail pressure data over an injection event (Krogerus), determining a slope parameter corresponding to a rail pressure drop (Krogerus derivative analysis), configuring and applying a pressure drop characterization to measured pressure data (Krogerus signal processing), and deriving hydraulic timing from that pressure drop behavior (Krogerus), within the common rail control framework of Barnes. As per claim 5, the combination of Barnes and Krogerus teaches the system as stated above. Barnes further teaches that the slope map is dependent upon at least one of an initial pressure (Pmax), a high-pressure volume of injection system, a temperature, a fuel type, and/or an injector type (see ¶¶ [0018] and [0029]-[0030], i.e., the injection timing delay and control duration are determined using rail pressure as an independent variable, and that model parameters are mapped and adapted as a function of rail pressure). Thus, the rail pressure prior to injection (corresponding to claimed Pmax because rail pressure is at its highest point prior to pressure drop caused by injection) is explicitly used as a dependency variable in mapped model parameters. As per claim 11, the combination of Barnes and Krogerus teaches the system as stated above. Barnes further teaches computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method (see ¶ [0007]). Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Barnes in view of Krogerus and further in view of Cracknell “the International Symposium Towards Clean Diesel Engines TCDE 2011” As per claim 6, the combination of Barnes and Krogerus teaches the system as stated above except that the method is implemented for fuel events configured to deliver fuel quantities of at least 10, 15 or 20mg. Cracknell, however, explicitly discloses experimental common-rail diesel injection events including “single injection of 20 mg/stroke” (see page 51), thereby evidencing that injection events configured to deliver at least 20 mg of fuel per event are conventional in common rail diesel systems. It would have been obvious to one having ordinary skill in the art before the effective filling date of the claimed invention to implement the timing determination and rail-pressure-based modeling methods of Barnes and Krogerus in connection with such conventional injection quantities (e.g., 10, 15 or 20 mg) as taught by Cracknell, because those references are directed broadly to common rail injection control and timing strategies without limitation to a specific injection mass, thereby rendering the claimed fuel-quantity range an obvious application of known operating conditions. Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over Barnes in view of Krogerus and further in view of Lai et al. (NPL: “Interpolation Methods for Time-Delay Estimation Using Cross-Correlation Method for Blood Velocity Measurement”) (hereinafter Lai). As per claim 7, the combination of Barnes and Krogerus teaches the system as stated above except for computing the pressure drop model for a plurality of timings and determining a corresponding fitting index reflecting the degree of matching between the fuel pressure data and the pressure drop model, and selecting the timing at which the best index is obtained. Lai, however, teach multi-candidate timing evaluation in the context of time-delay estimation using cross-correlation (see page 277, col.2), where Lai explicitly discloses estimating time delay by searching over candidate time shifts (Ԏ) and computing a correlation function R(Ԏ, 1), where the delay is determined by selecting the Ԏthat maximizes the correlation coefficient (i.e., R(Ԏv, 1) = max R(Ԏ, 1)). Lai further teaches refining the selected timing using interpolation techniques around the peak correlation to improve estimation accuracy (see page 278, co.2, section II. INTERPOALTION METHODS DESRIPTION) (i.e., the interpolation is necessary to get good time-delay estimation…the parabolic fitting is performed near the peak). It would have been obvious to one having ordinary skill in the rat before the effective filling date of the claimed invention to incorporate Lai’s teaching into the combination of Barnes and Krogerus’s teaching because Lai’s multi-candidate matching approach would improve the robustness and accuracy of hydraulic timing determination in the rail-pressure context. Thereby, yielding a more objective and repeatable best-fit injection timing. Claim 10 is rejected under 35 U.S.C. 103 as being unpatentable over Barnes in view of Krogerus and further in view of Bosh (CN10315448B). As per claim 10, the combination of Barnes and Krogerus teaches the system as stated above except that the hydraulic timing is stored and subsequently used for on-board diagnostic and/or fuel injection control. Bosh, however, teaches a monitoring and control method for adapting injector delay time, wherein delay time relationships are stored in the control device and used to compensate injector activation, and wherein deviations in injection behavior are detected and evaluated on board (e.g., via lambda/torque response) to diagnose injector drift and adapt timing parameters (see Contents of the invention, paragraphs 1-3) (the examiner notes that using lambda probe connected to the engine control unit, and the control unit adapts stored timing parameters accordingly. Such diagnostic evaluation performed by the engine control unit during vehicle operation constitutes on-board diagnostic processing). It would have been obvious to one having ordinary skill in the art before the effective filling date of the claimed invention to incorporate Bosh’s teaching into the combination of Barnes and Krogerus’s teaching because it would store the determined hydraulic timing for an on-board diagnostic evaluation and injection control adaptation, thereby enabling detection of injector timing deviations and maintaining accurate fuel injection control over the engine’s operating life. Allowable Subject Matter Claims 2-4 and 8 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. Regarding claim 2, none of the prior art of record teaches or fairly suggests a method of determining a hydraulic timing of a fuel injector in an internal combustion engine, wherein the injector is coupled to a fuel rail comprising a pressure sensor, the method comprising: wherein the pressure drop model is based on the slope parameter as well as on a maximum pressure, Pmax, and on a minimum pressure, Pmin, corresponding respectively to fuel rail pressures before and after the injection event, in combination with the rest of the claim limitations as claimed and defined by the applicant. Regarding claim 3, none of the prior art of record teaches or fairly suggests a method of determining a hydraulic timing of a fuel injector in an internal combustion engine, wherein the injector is coupled to a fuel rail comprising a pressure sensor, the method comprising: wherein the pressure drop model describes a function having a first section at Pmax, a middle section connecting the first section to a third section at Pmin, the middle section corresponding to a straight line having a slope matching to the slope parameter, in combination with the rest of the claim limitations as claimed and defined by the applicant. Regarding claim 8, none of the prior art of record teaches or fairly suggests a method of determining a hydraulic timing of a fuel injector in an internal combustion engine, wherein the injector is coupled to a fuel rail comprising a pressure sensor, the method comprising: wherein the fitting index represents the area between the curve described by the pressure data and the pressure drop model, and wherein the timing corresponding to the fitting index representing the smallest area is selected as hydraulic timing, in combination with the rest of the claim limitations as claimed and defined by the applicant. Prior art The prior art made record and not relied upon is considered pertinent to applicant’s disclosure: Schmitt [‘342] discloses a method for operating an internal combustion engine having a common-rail injection system as a function of a quantity of fuel injected. The method includes determining an information item about a relative-pressure characteristic from a characteristic of an absolute rail pressure in a high-pressure reservoir of the common-rail injection system; determining the quantity of fuel injected as a function of the information item about the relative-pressure characteristic, and with the aid of a trained functional model, in particular, a nonparametric functional model or a neural network; operating the internal combustion engine as a function of the quantity of fuel injected. Dingle [‘487] discloses a fuel injector for an internal combustion engine, the fuel injector comprising an injector body, a fuel supply passage defined in the injector body, the fuel supply passage containing fuel under high pressure in use of the injector, a pressure sensor for measuring the pressure of fuel in the passage in use, wherein the pressure sensor is situated within the injector body and is separated from fuel in the passage in use, and a method of fuel injection, comprising constructing an hydraulic behavior profile by fuel pressure measurement, using the hydraulic behavior profile to predict fuel pressure that will prevail in a fuel injector during an injection event, and supplying a control signal to the fuel injector to control the amount of fuel injected during the injection event in accordance with the predicted fuel pressure. By predicting the fuel pressure that will prevail during an injection event, the fuel delivered during the injection event can be accurately controlled. Hagner et al. [‘900] discloses a method for determining cylinder blow-through air via engine volumetric efficiency is disclosed. In one example, the method provides a way to adjust cylinder blow-through to promote and control a reaction in an exhaust after treatment device. The approach may simplify cylinder blow-through calculations and improve engine emissions via providing improved control of constituents reaching an exhaust after treatment device. Contact information Any inquiry concerning this communication or earlier communications from the examiner should be directed to MOHAMED CHARIOUI whose telephone number is (571)272-2213. The examiner can normally be reached Monday through Friday, from 9 am to 6 pm. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Andrew Schechter can be reached on (571) 272-2302. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. Information regarding the status of an application may be obtained from the Patent Application Information Retrieval (PAIR) system. Status information for published applications may be obtained from either Private PAIR or Public PAIR. Status information for unpublished applications is available through Private PAIR only. For more information about the PAIR system, see http://pair-direct.uspto.gov. Should you have questions on access to the Private PAIR system, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). Mohamed Charioui /MOHAMED CHARIOUI/Primary Examiner, Art Unit 2857
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Prosecution Timeline

Nov 22, 2023
Application Filed
Feb 21, 2026
Non-Final Rejection — §101, §103 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
81%
Grant Probability
94%
With Interview (+12.7%)
3y 4m
Median Time to Grant
Low
PTA Risk
Based on 686 resolved cases by this examiner. Grant probability derived from career allow rate.

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