Prosecution Insights
Last updated: April 19, 2026
Application No. 18/373,396

DUAL FUEL SYSTEM FOR ENGINE HAVING FUEL-ACTUATED FUEL PUMP AND METHOD

Non-Final OA §102§Other
Filed
Sep 27, 2023
Examiner
NGUYEN, HUNG Q
Art Unit
3747
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
Caterpillar Inc.
OA Round
1 (Non-Final)
83%
Grant Probability
Favorable
1-2
OA Rounds
2y 4m
To Grant
96%
With Interview

Examiner Intelligence

Grants 83% — above average
83%
Career Allow Rate
489 granted / 586 resolved
+13.4% vs TC avg
Moderate +12% lift
Without
With
+12.5%
Interview Lift
resolved cases with interview
Typical timeline
2y 4m
Avg Prosecution
14 currently pending
Career history
600
Total Applications
across all art units

Statute-Specific Performance

§101
0.6%
-39.4% vs TC avg
§103
34.0%
-6.0% vs TC avg
§102
36.6%
-3.4% vs TC avg
§112
22.7%
-17.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 586 resolved cases

Office Action

§102 §Other
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 . Election/Restrictions Claims 21-26 have been withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention, there being no allowable generic or linking claim. Election was made without traverse in the reply filed on 02/20/2026. Currently, claims 1-20 are pending prosecution. Claim Rejections - 35 USC § 102 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention. (a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention. Claim(s) 1-2, 5-7, 10-16 is/are rejected under 35 U.S.C. 102a1 & 102a2 as being clearly anticipated by Haas (US 20140238351 A1). Haas ‘351 discloses the invention as follows: 1. A dual fuel system (e.g., liquid fuel system 100 & gaseous fuel system 120; fig. 3; [0022] states “…fuel apparatus 100 comprising liquid fuel system 110, gaseous fuel system 120, internal combustion engine 130 and electronic controller 140. Liquid fuel system 110 comprises liquid fuel supply system 112, a liquid fuel pump 115 and liquid fuel delivery system 117. Liquid fuel supply system 112 provides a supply of liquid fuel, which can be diesel, bio-diesel, gasoline (petrol) and ethanol gasoline blends. Liquid fuel pump 115 is a common rail pump, such as a diesel common rail pump or a gasoline common rail pump. Pump 115 pressurizes liquid fuel received from supply system 112 to a first pressure suitable for fuel injection and provides it to engine 130 through delivery system 117.”) comprising: a first pressurized fuel reservoir 290 (fig. 3; [0023] “Pressure regulator 280 is operable to regulate the pressure of the liquid fuel from pump 115 such that the pressure within liquid-fuel common rail 290 is stable and suitable for fuel injection system 150. In other embodiments an inlet metering valve (not shown) that is controlled by electronic controller 140 and located between conduit 200 and inlet valve 240 can regulate the pressure of the liquid fuel in conduit 460. Pressurized liquid fuel is communicated from regulator 280 through fuel conditioning module 285 to common rail 290. The function of fuel conditioning module 285 is to regulate the differential pressure between the liquid fuel and the gaseous fuel, as will be described in further detail below, such that pressure of the liquid fuel from regulator 280 is substantially the same as the pressure of the liquid fuel in common rail 290. Electronic controller 140 is responsive to pressure sensor 300, which is operable to measure the pressure of the liquid fuel in common rail 290, in order to control pump 115 and regulator 280 to maintain a suitable pressure of the liquid fuel in rail 290.”); a first fuel pump 115 fluidly connected to the first pressurized fuel reservoir 290; a second pressurized fuel reservoir (e.g., accumulator 390; fig. 3; [0024] “In the illustrated embodiment, compressor 320 is a reciprocating piston-type pump, such as that described in the aforementioned '482 patent, and operates to elevate the pressure of the gaseous fuel to a pressure suitable for one or more fuel injectors 500 in fuel injection system 150. As used herein the term pump refers to a pump or a compressor for elevating the pressure of a fluid that can be in a liquid phase, a gaseous phase or a multi-phase. Compressor 320 comprises inlet port 330, outlet port 340 and hydraulic port 350. Flow switching device 360 operates to control the flow of hydraulic fluid with respect to compressor 320 between a compression stroke and an intake stroke, which will be described in further detail below. The gaseous fuel from outlet port 340 is communicated through heat exchanger 370 to lower the elevated temperature of the gaseous fuel, due to compression, in order to prevent negative combustion effects in engine 130. Accumulator 390 provides a reservoir of gaseous fuel at the desired pressure to reduce pressure fluctuations caused by compressor 320 (or by an LNG pump) and to avoid sudden drops in pressure, for example when there is a sudden high demand for fuel.”); and a second fuel pump (e.g., compressor 320) including a pump outlet 340 fluidly connected to the second pressurized fuel reservoir 390, a pumping chamber (e.g., compression chamber 710; fig. 8; [0030] “Referring to the sectional plan views of FIGS. 7 and 8, alternative embodiments of compressor 320 are now described. Compressors 322 and 324 operate on the same principle as the free-floating piston compressor disclosed in the aforementioned '482 patent and generally only differences are discussed. It is understood that other types of pumps other than compressors 320, 322 and 324 can be employed in gaseous-fuel pumping system 125 shown in FIG. 1, and the following descriptions of free-floating piston-type compressors in no way limits the types of pumps that can be employed. In some applications the capacity of liquid fuel pump 115 as seen in FIGS. 1 to 6 may not be sufficient to meet the flow requirements of compressor 320 for pressurized liquid fuel. In these situations it is advantageous to employ reciprocating piston-type compressor 322 as illustrated in FIG. 7. Compressor 322 comprises piston 700, compression chamber 710 and driving chamber 720. Piston 700 comprises driving face 730 and compression face 740. The ratio of area A.sub.DF of driving face 730 to area A.sub.CF of compression face 740 is less than one by design.”) fluidly connected to the pump outlet 340 (fig. 3), an actuating fluid inlet 350 (fig. 3; [0024] “As used herein the term pump refers to a pump or a compressor for elevating the pressure of a fluid that can be in a liquid phase, a gaseous phase or a multi-phase. Compressor 320 comprises inlet port 330, outlet port 340 and hydraulic port 350.” and [0025] “During the compression stroke of compressor 320, flow switching device 360 receives the liquid fuel from pressure regulator 450 at inlet port 420 and directs the liquid fuel to port 430 where it is then applied to hydraulic port 350 of compressor 320. The liquid fuel enters hydraulic port 350 and operates to move a piston within compressor 320 to compress the gaseous fuel within a compression chamber. The piston in compressor 320 is a single-acting piston in the present example whereby the liquid fuel acts only on one face of the piston. A pulsed flow of the liquid fuel from liquid-fuel pump 115 is required for compressor 320 due to the single-acting piston.”) fluidly connected to at least one of the first fuel pump 115 or the first pressurized fuel reservoir 290, and at least one pumping element (e.g., piston 700; fig. 8) having an actuating surface (driving face 730) exposed to a fluid pressure of the actuating fluid inlet 350 (fig. 3), and a pumping surface (compression face 740) exposed to the pumping chamber (compression chamber 710). 2. The dual fuel system of claim 1 wherein the at least one pumping element 700 (fig. 8) includes a reverse intensifier plunger wherein the actuating surface 730 has a first area and the pumping surface 740 has a second area larger than the first area ([0030] “The ratio of area A.sub.DF of driving face 730 to area A.sub.CF of compression face 740 is less than one by design.”). 5. The dual fuel system of claim 1 further comprising a plurality of fuel injection nozzle assemblies (fuel injectors 500; fig. 3 [0022] “In the illustrative embodiments that show both liquid and gaseous fuel delivered to the fuel injectors, the fuel injectors are preferably of the type that can inject two different fuels separately and independently into the combustion chamber, such as the fuel injectors described in the applicant's own U.S. Pat. Nos. 6,439,192 and 6,761,325. Electronic controller 140 communicates with and commands liquid fuel system 110, gaseous fuel system 120 and fuel injection system 150 to deliver and inject fuel for combustion in cylinders 155.” and [0026] “…fuel injection system 150 comprises fuel injectors 500 which are dual-fuel injectors in the present example. Liquid-fuel common rail 290 provides the liquid fuel at liquid-fuel injection pressure to injectors 500, and gaseous-fuel common rail 410 provides the gaseous fuel at gaseous-fuel injection pressure to injectors 500. Electronic controller 140 commands injectors 500 to inject the liquid fuel and the gaseous fuel independently and separately of each other by actuating respective valve members therein. Each of the fuel injectors 500 communicates with return conduit 505 to return liquid fuel not used in combustion through return port 600 to liquid fuel tank 160. Fuel conditioning module 285 also communicates with return conduit 505 to return liquid fuel when common rail 290 is at full capacity.”) each including a first fuel outlet set, a first injection valve movable to open and close the first fuel outlet set to the first pressurized fuel reservoir, a second fuel outlet set, and a second injection valve movable to open and close the second fuel outlet set to the second pressurized fuel reservoir. 6. The dual fuel system of claim 5 wherein each respective first fuel outlet set and first injection valve together define a lesser steady flow (e.g., for injection of pilot diesel fuel), and each respective second fuel outlet set and second injection valve together define a greater steady flow (e.g., for injection of gaseous (natural) fuel as main fuel; [0026] “the liquid fuel is diesel fuel and the gaseous fuel is natural gas, and fuel injectors 500 injectors inject diesel as a pilot fuel and natural gas as a main fuel.”). 7. The dual fuel system of claim 5 wherein each respective first injection valve and second injection valve includes a hydraulic control surface exposed to a fluid pressure of the first pressurized fuel reservoir (not explicitly shown in fig. 3; but as evidenced by US 6,761,325 B2 and fig. 3-6 and “Outer needle 17 preferably controls the injection of gaseous main fuel since larger ejection ports are generally required for injecting larger quantities of main fuel compared to pilot fuel, and larger fuel ejection ports are more easily accommodated in the valve body rather than in the tip of outer needle 17. The smaller pilot fuel ejection ports can be can be easily accommodated in tip of outer needle 17. Main fuel control valve 11 controls the flow of hydraulic fluid from chamber 20 to drain 10. When main fuel control valve 11 is in a closed position, high pressure hydraulic fluid flows through inlet 8 and orifice 8a and fills chamber 20. When main fuel control valve 11 is switched to an open position, hydraulic fluid drains from chamber 20 faster than it can be replenished through orifice 8a. Consequently, when main fuel control valve is open, the pressure within chamber 20 drops from the high pressure that is in the supply manifold ("rail pressure"), to close to drain pressure and the pressure of the main fuel in chamber 22 applies an opening force to a shoulder area of outer needle 17, causing outer needle 17 to retract within the injection valve body so that fuel within chamber 22 flows into the combustion chamber through ejection ports 4. Main fuel cavity 22 is located in the bottom region of injection valve 1 and surrounds the lower portion of main fuel needle 17. The main fuel, which in preferred embodiments is gaseous fuel such as natural gas, is supplied to cavity 22 through inlet 23. Differential pressures within injection valve 1 and particularly between main fuel cavity 22 and the other cavities within the main body of injection valve 1 are preferably sealed by a fluid seal comprising hydraulic fluid disposed within fluid seal cavity 24, as best seen in FIGS. 4 and 5. Hydraulic fluid is supplied to the injection valve through a supply manifold or common rail at a substantially constant pressure. For example, in vehicular applications, an engine driven pump can be employed to pressurize the hydraulic fluid that is directed to the common rail. When the hydraulic fluid is different from the pilot fuel, the hydraulic fluid is introduced through ports 7 and 8 and the pilot fuel is introduced through inlet port 6. More preferably, the pilot fuel is a liquid fuel such as diesel, which can also be employed as the hydraulic fluid, and pilot fuel is supplied to ports 6, 7 and 8 from a common pressurized system or common rail. The rail pressure is the pressure of the fluid in the common rail.”). With regards to claim(s) 10, the claim(s) is/are commensurate in scope with claim(s) 1 & 5, and is/are rejected for the same reasons as set forth above. Re claims 11-12, Haas ‘351 teaches the method further comprising compression igniting the pressurized first fuel (diesel fuel as pilot fuel) in the plurality of cylinders, and igniting the pressurized second fuel (gaseous fuel such as natural gas as main fuel) in the plurality of cylinders via the compression ignition of the pressurized first fuel ([0026] “the liquid fuel is diesel fuel and the gaseous fuel is natural gas, and fuel injectors 500 injectors inject diesel as a pilot fuel and natural gas as a main fuel.”), and wherein the injecting the pressurized first fuel includes injecting a pilot quantity (pilot fuel) of the pressurized first fuel (pressurized diesel fuel), and the injecting the pressurized second fuel includes injecting a larger quantity (main fuel) of the pressurized second fuel (pressurized gaseous fuel) ([0026] “the liquid fuel is diesel fuel and the gaseous fuel is natural gas, and fuel injectors 500 injectors inject diesel as a pilot fuel and natural gas as a main fuel.”). Re claims 13-16, Haas ‘351 teaches the method wherein the pressurized first fuel includes a diesel fuel, and the pressurized second fuel includes an alcohol fuel, and wherein the actuating the second fuel pump 320 (fig. 3) includes actuating a plunger (e.g., piston 700; fig. 8) having an actuation surface 730 exposed to a fluid pressure of the pressurized first fuel, and a pumping surface 740 exposed to a pumping chamber 710 containing the second fuel, and wherein the feeding the pressurized first fuel includes feeding the pressurized first fuel at a first flow rate (e.g., as pilot injection of diesel/gasoline fuel), and the feeding the pressurized second fuel includes feeding the pressurized second fuel at a second flow rate (e.g., as main injection of second gaseous fuel) that is greater than the first flow rate, and wherein an outlet pressure (at 250) of the first fuel pump 115 is greater than an outlet pressure (at 340) of the second fuel pump 320 ([0023] “Pressure regulator 280 is operable to regulate the pressure of the liquid fuel from pump 115 such that the pressure within liquid-fuel common rail 290 is stable and suitable for fuel injection system 150. In other embodiments an inlet metering valve (not shown) that is controlled by electronic controller 140 and located between conduit 200 and inlet valve 240 can regulate the pressure of the liquid fuel in conduit 460. Pressurized liquid fuel is communicated from regulator 280 through fuel conditioning module 285 to common rail 290. The function of fuel conditioning module 285 is to regulate the differential pressure between the liquid fuel and the gaseous fuel, as will be described in further detail below, such that pressure of the liquid fuel from regulator 280 is substantially the same as the pressure of the liquid fuel in common rail 290. Electronic controller 140 is responsive to pressure sensor 300, which is operable to measure the pressure of the liquid fuel in common rail 290, in order to control pump 115 and regulator 280 to maintain a suitable pressure of the liquid fuel in rail 290.”). Allowable Subject Matter Claims 3-4, 8-9 and 17 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. The following is a statement of reasons for the indication of allowable subject matter: with regards to claim 3, the prior art made of record neither discloses nor render obvious the combination set forth in the independent claim, and especially does not show “wherein the second fuel pump includes an electrically actuated flow control valve positioned fluidly between the actuating fluid inlet and the actuating surface” in combination with the other claim limitations. The following is a statement of reasons for the indication of allowable subject matter: with regards to claim 8, the prior art made of record neither discloses nor render obvious the combination set forth in the independent claim, and especially does not show “a third pressurized fuel reservoir; and a fuel manifold positioned fluidly between the second fuel pump and each of the second pressurized fuel reservoir and the third pressurized fuel reservoir” in combination with the other claim limitations. The following is a statement of reasons for the indication of allowable subject matter: with regards to claim 17, the prior art made of record neither discloses nor render obvious the combination set forth in the independent claim, and especially does not show “feeding the pressurized second fuel to a third pressurized fuel reservoir via a fuel manifold having a fuel inlet, two fuel outlets fluidly connected, respectively, to the second pressurized fuel reservoir and the third pressurized fuel reservoir, a purging gas inlet, and a purging gas valve positioned fluidly between the purging gas inlet and at least one of the two fuel outlets” in combination with the other claim limitations. Claims 18-20 are allowed. The following is a statement of reasons for the indication of allowable subject matter: with regards to claim 18, the prior art made of record neither discloses nor render obvious the combination set forth in the independent claim, and especially does not show “the second fuel pump further including a plurality of hydraulically actuated pumping elements each including an actuation surface, an actuating fluid inlet fluidly connected to the first fuel pump, and a plurality of electrically actuated flow control valves each positioned fluidly between the actuating fluid inlet and the actuation surface of one of the plurality of hydraulically actuated pumping elements” in combination with the other claim limitations. Conclusion The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. The various cited prior arts teach dual fuel injection system for internal combustion engines where the fuel injectors are capable of injecting both the pilot fuel and main fuel thru separate fuel injection outlet valves. Any inquiry concerning this communication or earlier communications from the examiner should be directed to HUNG Q NGUYEN whose telephone number is (571)270-5424. The examiner can normally be reached Mon-Fri: 7am-pm (CT). 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. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Lindsay Low can be reached at 571-272-1196. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. HUNG Q. NGUYEN Primary Examiner Art Unit 3747 /HUNG Q NGUYEN/Primary Examiner, Art Unit 3747
Read full office action

Prosecution Timeline

Sep 27, 2023
Application Filed
Mar 31, 2026
Non-Final Rejection — §102, §Other (current)

Precedent Cases

Applications granted by this same examiner with similar technology

Patent 12601288
ACTIVE COOLANT MONITORING AND LEAK MITIGATION IN VEHICLE COOLING SYSTEMS
2y 5m to grant Granted Apr 14, 2026
Patent 12595758
OPTIMAL EFFICIENCY INTERNAL COMBUSTION ENGINE
2y 5m to grant Granted Apr 07, 2026
Patent 12595755
Rocker Arm for Brake with Integrated Hydraulic Capsule
2y 5m to grant Granted Apr 07, 2026
Patent 12595771
VEHICLE WITH ENGINE
2y 5m to grant Granted Apr 07, 2026
Patent 12587039
WIRELESS CHARGING AND DOCKING STATION, SYSTEM AND ASSOCIATED METHOD
2y 5m to grant Granted Mar 24, 2026
Study what changed to get past this examiner. Based on 5 most recent grants.

AI Strategy Recommendation

Get an AI-powered prosecution strategy using examiner precedents, rejection analysis, and claim mapping.
Powered by AI — typically takes 5-10 seconds

Prosecution Projections

1-2
Expected OA Rounds
83%
Grant Probability
96%
With Interview (+12.5%)
2y 4m
Median Time to Grant
Low
PTA Risk
Based on 586 resolved cases by this examiner. Grant probability derived from career allow rate.

Sign in with your work email

Enter your email to receive a magic link. No password needed.

Personal email addresses (Gmail, Yahoo, etc.) are not accepted.

Free tier: 3 strategy analyses per month