WO2015200443A1 - Combustion mode transition methods for dual-fuel engines - Google Patents

Combustion mode transition methods for dual-fuel engines Download PDF

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Publication number
WO2015200443A1
WO2015200443A1 PCT/US2015/037352 US2015037352W WO2015200443A1 WO 2015200443 A1 WO2015200443 A1 WO 2015200443A1 US 2015037352 W US2015037352 W US 2015037352W WO 2015200443 A1 WO2015200443 A1 WO 2015200443A1
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WIPO (PCT)
Prior art keywords
transition
diesel
engine
gaseous fuel
fuel
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Application number
PCT/US2015/037352
Other languages
French (fr)
Inventor
Axel Otto ZUR LOYE
Robert J. Thomas
Christopher POLLITT
Original Assignee
Cummins Inc.
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Publication date
Application filed by Cummins Inc. filed Critical Cummins Inc.
Publication of WO2015200443A1 publication Critical patent/WO2015200443A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
    • F02D19/08—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed simultaneously using pluralities of fuels
    • F02D19/081—Adjusting the fuel composition or mixing ratio; Transitioning from one fuel to the other
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
    • F02D19/08—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed simultaneously using pluralities of fuels
    • F02D19/10—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed simultaneously using pluralities of fuels peculiar to compression-ignition engines in which the main fuel is gaseous
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D31/00—Use of speed-sensing governors to control combustion engines, not otherwise provided for
    • F02D31/001—Electric control of rotation speed
    • F02D31/007—Electric control of rotation speed controlling fuel supply
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F02D41/402—Multiple injections
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0002—Controlling intake air
    • F02D41/0007—Controlling intake air for control of turbo-charged or super-charged engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0027—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures the fuel being gaseous
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F02D41/402—Multiple injections
    • F02D41/403—Multiple injections with pilot injections
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F02D41/402—Multiple injections
    • F02D41/405—Multiple injections with post injections
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • the present application relates generally to combustion mode transition techniques, methods, apparatuses and systems for dual-fuel engines.
  • Dual-fuel engines hold the promise of a number of potential economic and environmental benefits through the combustion of different ratios of two or more types of fuels during different modes of operation.
  • a dual-fuel engine may operate as a diesel engine during certain operating modes and may combust a variety of ratios of diesel fuel and gaseous fuel during other modes of operation. Transition between modes of operation in dual-fuel engines presents a unique set of technical challenges.
  • a number of proposals have been made for controlling dual-fuel engines in multiple operating.
  • Existing attempts to control dual-fuel engines in multiple fueling modes suffer from a number of drawbacks, problems and shortcomings. There remains a significant need for the unique controls techniques, methods, systems, and apparatuses disclosed herein.
  • FIG. 1 illustrates an exemplary dual-fuel engine system.
  • FIG. 2 illustrates a flow diagram according to exemplary controls for a dual-fuel engine system.
  • FIG. 3 illustrates a flow diagram according to further exemplary controls for a dual-fuel engine system.
  • Fig. 4 illustrates graphs of mode transition and mode stability criteria satisfied values as functions of time.
  • Fig. 5 illustrates a graph of a diesel fueling control parameter and a gaseous fueling control parameter as a function of time.
  • FIG. 1 With reference to Fig. 1 there is illustrated an exemplary dual-fuel engine system
  • Diesel fueling system 120 is preferably configured as a high pressure common rail injection system which draws diesel fuel form a source 121, pressurizes diesel fuel with a pump 122 and provides pressurized diesel fuel to a common rail injection system 123 including a plurality of injectors configured to inject diesel fuel into the cylinders of engine 110. It shall be appreciated that diesel fueling system 120 is one example of a liquid fuelling system and that a variety of other liquid fuels and fueling systems may be utilized.
  • Intake system 130 includes an air filter 131 which receives and filters ambient air, a compressor 132 which compresses intake air, and an intake manifold 133 which provides intake air to the cylinders of engine 110.
  • Intake system 130 further includes a gaseous fueling system 137 including a gaseous fuel supply 135 and a control valve system 134 including at least one valve configured to control the supply of gaseous fuel provided to the compressor 132.
  • Intake system 130 may include a mixer or other flow connection configured to mix air with the secondary fuel.
  • the mixer may be positioned at a variety of locations in the intake system 130 including the illustrated position upstream of the compressor 132 as well as at the inlet to the compressor 132, at or after the outlet of compressor 132. Gaseous fuel could also be introduced into the intake manifold or intake ports.
  • the intake system 130 may also include a charge air cooler, such as, for example, an air-to-air heat exchanger, an air-to-liquid heat exchanger, or a combination of both that facilitates the transfer of thermal energy to or from the charge flow.
  • Exhaust system 140 includes an exhaust manifold 143 which receives exhaust from the combustion cylinders of engine 110 and provides exhaust to a turbine 142 which is operatively couple with compressor 132.
  • Exhaust system 140 further includes an aftertreatment system 141 configured to mitigate one or more exhaust constitutes.
  • the aftertreatment system includes a diesel oxidation catalyst (DOC), diesel particulate filter DPF, and selective catalytic reduction (SCR) catalyst.
  • DOC diesel oxidation catalyst
  • DPF diesel particulate filter
  • SCR selective catalytic reduction
  • Other forms may include additional or alternate exhaust aftertreatment components as well as subsets of the foregoing components.
  • Controller 190 is operatively coupled with a plurality of other components and systems of engine system 100 and is configured to operate engine system 100 in a first mode which combusts a first ratio of diesel fuel and gaseous fuel, and a second mode which combusts a second ratio of diesel fuels and gaseous fuel.
  • the first ratio comprises a diesel-only mode (e.g., a substantially 1 :0 ratio of diesel fuel to gaseous fuel)
  • the second ratio comprises a dual-fuel mode (e.g., an M:N ratio of diesel fuel to gaseous fuel greater than 1 :0).
  • the diesel only mode the engine 100 operates as a diesel engine and combusts only diesel fuel provided by diesel fueling system 120.
  • a supplementary gaseous fuel is added to the combustion cycle by gaseous fueling system 137.
  • the supplementary gaseous fuel may be, for example, natural gas, bio-gas, methane, propane, ethanol, producer gas, field gas, liquefied natural gas (LNG), compressed natural gas (CNG), liquefied petroleum gas (LPG), or landfill gas.
  • LNG liquefied natural gas
  • CNG compressed natural gas
  • LPG liquefied petroleum gas
  • landfill gaseous fuel may be introduced via fumigation and/or port injection as well as via in-cylinder injection.
  • the amount of diesel fuel combusted may be reduced according to the amount of gaseous fuel being introduced into the combustion cylinder.
  • Controller 190 may be configured to provide control commands that regulate the amount, timing, and duration of the first and secondary fuels provided to engine 1 10, the charge flow, and the exhaust flow to at least attempt for the engine system 100 to provide a desired torque and exhaust output. Accordingly, the controller 190 can be connected to various actuators, switches, sensors, or other devices associated with control of charge air flow, exhaust flow, and fueling amounts. For example, according to certain embodiments, the controller 190 may be in operable communication with one or more components and/or sensors associated with diesel fueling system 120 as well as gaseous fueling system 137. Controller 190 may further be connected with an intake throttle, an exhaust throttle, a compressor bypass, or a turbine geometry adjustment mechanism.
  • the controller 190 may also be operably connected to a variety of different sensors that detect and/or provide information relating to the operation of the engine system 100.
  • the controller 190 may be operably connected to a throttle sensor that detects the position of a throttle, an intake air temperature sensor, and exhaust temperature sensor, one or more after-treatment system sensors such as temperature sensors, lambda sensors, oxygen sensors, or NOx sensors.
  • the controller 190 is structured to form a portion of a processing system including one or more computing devices having memory, processing, and communication hardware in operative communication over one or more controller area network (CAN) systems.
  • the controller 190 may be a single device or a distributed device, and the functions of the controller 190 may be performed by hardware or software.
  • the controller 190 may be included within, partially included within, or completely separated from an engine controller (not shown).
  • the controller 190 can also be in communication with any sensor or actuator throughout the systems disclosed herein, including through direct communication, communication over a datalink, and/or through communication with other controllers or portions of the processing subsystem that provide sensor and/or actuator information to the controller 190.
  • Controller 190 may be configured to transition between operating modes while maintaining acceptable performance, emissions, and mechanical limits. A number of methods for managing such transitions while avoiding engine knock, misfire, and transient emissions among other considerations are disclosed herein. Certain exemplary transition methods utilizes a transition mode operating table which is predetermined to avoid one or more predetermined operating events, such as engine knock, during a transition from a first combustion mode to a second combustion mode. In some forms the transition mode operating table may be utilized from a time at or after a gaseous fuel valve is opened to a time when the gaseous fuel valve achieves a final opened position at which time an alternate operating table may be used.
  • a transition mode operating table which is predetermined to avoid one or more predetermined operating events, such as engine knock
  • the transition mode operating table may be utilized form a time at or after a gaseous fuel valve is opened to a time when the gaseous fuel valve achieves a transition opened position which is determined based upon a final opened position at which time an alternate control criteria may be used.
  • Certain exemplary transition methods comprise the following operations: (i) identify a need to change modes, (ii) determine final gas valve open position based on desired conditions, commands, or other criteria, (iii) determine transition gas valve open position (e.g., 90% of final) and lock on an infinite lambda table (e.g., a table constructed to control combustion assuming an infinite lambda value) until transition to 90% of final, (iv) open gas valve to transition position at predetermined rate, (v) once transition complete, allow diesel governor to manage engine speed to target speed, and (vi) achieve final gas valve open position based on engine operating parameters.
  • transition gas valve open position e.g. 90% of final
  • an infinite lambda table e.g., a table constructed to control combustion assuming an infinite lambda value
  • Certain exemplary transition methods include the following operations: (i) identify need (signal) to transition between modes, (ii) switch engine operation to a special set of diesel injection control parameters represented by a 3 -dimensional response surface (or another type of calibration table) specifying various parameters such as diesel injection timing, injection pressure, and multiple injection strategy (e.g. pilot, main, and/or post) wherein the table is designed in a manner to avoid engine knock, misfire, and other undesirable conditions, (iii) open a gaseous fuel control valve wherein the valve may be opened at a predetermined rate (time based), opened abruptly (single command) to a final/fixed position or opened based on other parameters (i.e.
  • engine speed governor diesel fueling quantity, measured or estimated gas substitution rate, vehicle or application load feedback, intake manifold pressure, intake manifold temperature, exhaust temperature, cylinder pressure, engine knock sensor, etc), and (iv) as the actual operating condition (speed & load) approaches the target operating condition, begin the transition away from the special set of diesel injection control parameters of operation (ii) based on a predetermined stability criteria wherein the stability criteria may include actual commanded diesel fueling quantity relative to target desired fueling quantity, and/or sensed gas substitution rate relative to targeted gas substitution rate.
  • control routine 200 which may be stored in a non-transitory controller readable memory medium and executed by controller 190 to control operation of a dual fuel engine system such as system 100 described herein or other types of dual fuel engine systems.
  • Control routine 200 is initiated at operation 201 and proceeds to operation 210.
  • Operation 210 computes diesel injection system control parameters based on pre-transition mode operating conditions.
  • operation 210 utilizes a set of multi-dimensional tables to determine diesel injection parameters based on engine speed and engine load.
  • operation 210 uses a set of three-dimensional response surfaces to determine timing and quantity values for a pre-injection, a main injection and a post-injection and a rail pressure value.
  • the pre-transition mode diesel fueling parameters may be for a diesel-only operating mode or for a dual-fuel operating mode depending on the operating condition of engine system 100.
  • Operation 210 also computes gaseous fuel system control parameters based on pre-transition mode operating conditions.
  • operation 210 computes a valve position to provide a predetermined quantity of gaseous fuel and a charge flow parameter which may be controlled, for example, by controlling compressor boost pressure and/or intake throttle position.
  • the pre-transition mode diesel fueling parameters may be for a diesel-only operating mode in which the valve is completely closed, or for a dual-fuel operating mode in which the valve opened depending on the operating condition of engine system 100.
  • Operation 210 also monitors mode transition criteria for subsequent conditional evaluation.
  • conditional 215 evaluates whether a mode transition condition is detected.
  • Conditional 215 may make this evaluation based upon a variety of criteria, for example, a mode transition command, an engine load, an engine speed, a commanded gaseous fuel substitution rate or a combination thereof. If conditional 215 determines that no mode transition is detected process 200 returns to operation to operation 210 and performs the operations described above. If conditional 215 determines that a mode transition is detected process 200 proceeds to operation to 220.
  • Operation to 220 determines target post-transition mode gaseous fuel system control parameters.
  • these parameters include a valve position parameter and an intake charge flow parameter which provide a desired quantity of gaseous fuel once transition to a new operating mode is complete.
  • Operation to 220 also determines transition mode gaseous fuel system control parameters as a function of the target post-transition mode control parameters.
  • the transition mode gaseous fuel system control parameters are determined as a function of a predetermined percentage of the parameter values associated with the target post-transition mode conditions relative to the parameter values associated with the pre-transition mode conditions, and the parameter values associated with the pre-transition mode conditions.
  • TMGP a*PTGP - b*(TPTGP/PTGP)
  • TMGP b*(TPTGP/PTGP) - a*PTGP
  • TMGP a*PTGP + b*(PTGP/ TPTGP)
  • TMGP a*PTGP - b*(PTGP/ TPTGP)
  • TMGP b*(PTGP/ TPTGP) - a*PTGP.
  • control routine 200 proceeds to operation 230 which computes diesel injection system control parameters based on a transition mode specific operating table.
  • the transition mode specific operating table provides a predetermined set of diesel injection control parameters represented by a three-dimensional response surface or other type of calibration table.
  • the three-dimensional response surface specifies various calibratable parameters such as diesel injection timing, injection pressure, and multiple injection events (e.g., pilot, main, and/or post).
  • the transition mode specific operating table is configured to avoid engine knock, misfire, and other undesirable conditions during transition. This may be accomplished, for example, by assuming that operation is occurring at a predetermined air to fuel ratio or a predetermined lambda value.
  • the three-dimensional response surface specifies calibratable parameters for an infinite lambda condition
  • Operation 230 also transitions computed gaseous fuel system control parameters from values determined from a pre-transition mode operating condition to a determined required transition value.
  • operation 230 commands opening of a gaseous fuel control valve.
  • the gaseous fuel control valve may be opened at a predetermined rate (e.g., time based), or may be opened abruptly (e.g., single command) to a final/fixed position.
  • the gaseous fuel control valve may be opened based on various parameters (e.g., engine speed governor, diesel fueling quantity, measured or estimated gas substitution rate, vehicle or application load feedback, intake manifold pressure, intake manifold temperature, exhaust temperature, cylinder pressure, and/or engine knock sensor, to name several examples.)
  • control routine 200 proceeds to conditional 235 which evaluates whether gaseous fuel system control parameters are equal to required transition mode values. If conditional 235 evaluates no, process 200 returns to operation 230 and repeats the operations described above. If conditional 235 evaluates yes, process 200 proceeds to operation 240.
  • Operation 240 computes diesel injection system control parameters based on post- transition mode operating conditions. Operation 240 also computes gaseous fuel system control parameters based on post-transition operating conditions. From operation 240 process 200 proceeds to end state 299 it being appreciated that from end state 299, process 200 may repeat when called upon or after a predetermined time.
  • Fig.2 will both avoid engine knock, combustion misfire, and an engine over speed condition resulting from an initial oversupply of gaseous fuel in combination with the standard amount of diesel fueling (i.e. engine over speed can occur if too much gaseous fuel is introduced before the diesel fueling has time to react (reduce) to the presence of the supplemental gas.
  • control routine 300 which may be stored in a non-transitory controller readable memory medium and executed by controller 190 to control operation of a dual fuel engine system such as system 100 described herein or other types of dual fuel engine systems.
  • Control routine 300 is initiated at operation 301 and proceeds to operation 310.
  • Operation 310 computes diesel injection system control parameters based on pre-transition mode operating conditions.
  • operation 310 utilizes a set of multi-dimensional tables to determine diesel injection parameters based on engine speed and engine load.
  • operation 310 uses a set of three-dimensional response surfaces to determine timing and quantity values for a pre-injection, a main injection and a post-injection and a rail pressure value.
  • the pre-transition mode diesel fueling parameters may be for a diesel-only operating mode or for a dual-fuel operating mode depending on the operating condition of engine system 100.
  • Operation 310 also computes gaseous fuel system control parameters based on pre-transition mode operating conditions.
  • operation 310 computes a valve position to provide a predetermined quantity of gaseous fuel and a charge flow parameter which may be controlled, for example, by controlling compressor boost pressure and/or intake throttle position.
  • the pre-transition mode diesel fueling parameters may be for a diesel-only operating mode in which the valve is completely closed, or for a dual-fuel operating mode in which the valve opened depending on the operating condition of engine system 100.
  • Operation 310 also monitors mode transition criteria for subsequent conditional evaluation.
  • conditional 315 evaluates whether a mode transition condition is detected.
  • Conditional 315 may make this evaluation based upon a variety of criteria, for example, a mode transition command, an engine load, an engine speed, a commanded gaseous fuel substitution rate or a combination of the foregoing and/or other parameters. If conditional 315 determines that no mode transition is detected process 300 returns to operation to operation 310 and performs the operations described above. If conditional 315 determines that a mode transition is detected process 300 proceeds to operation to 320. [00030] Operation 320 computes diesel injection system control parameters based on a transition mode specific operating table.
  • the transition mode specific operating table provides a predetermined set of diesel injection control parameters represented by a three-dimensional response surface or other type of calibration table.
  • the three-dimensional response surface specifies various calibratable parameters such as diesel injection timing, injection pressure, and multiple injection strategy (e.g., pilot, main, and/or post).
  • the transition mode specific operating table is configured to avoid engine knock, misfire, and other undesirable conditions during transition. This may be accomplished, for example, by assuming that operation is occurring at a predetermined air to fuel ratio or a predetermined lambda value.
  • the three- dimensional response surface specifies calibratable parameters for an infinite lambda condition.
  • Operation 320 also computes gaseous fuel system control parameters based on target post transition mode conditions. These parameters may be determined based on a desired quantity or substitution rate of gaseous fuel as well as a variety of other parameters. Operation 320 also monitors one or more mode stability criteria for subsequent evaluation. From operation 320 process 300 proceeds to conditional 325.
  • Conditional 325 evaluates whether one or more monitored mode stability criteria are satisfied.
  • Exemplary mode stability criteria may include actual commanded diesel fueling quantity relative to target desired fueling quantity, and/or 2) sensed gas substitution rate relative to targeted gas substitution rate. If conditional 325 determines that the monitored mode stability criteria are not satisfied, process 300 returns to operation 320. If conditional 325 determines that the monitored mode stability criteria are satisfied, process 300 proceeds to operation 330.
  • Operation 330 transitions computed diesel injection parameters from values determined from the transition mode specific response surface to values determined from post- transition operating conditions. Operation 330 also computes gaseous fuel system control parameters based on post transition mode operating conditions. From operation 330 process 300 proceeds to end state 399 it being appreciated that from end state 399, process 300 may repeat when called upon or after a predetermined time.
  • Graph 410 illustrates mode transition value as a function of time. Up to a transition time 401 the mode transition value has a logic value indicating no mode transition. At the transition time 401 the mode transition value transitions to a logic value indicating a mode transition.
  • Graph 420 illustrates a mode transition stability criteria satisfied value as a function of time. Up to a stabilization time 403 subsequent to transition time 401 the mode transition stability criteria satisfied value has a logic value indicating that the mode transition stability criteria are not satisfied. After the stabilization time 403 the mode transition stability criteria satisfied value has a logic value indicating that the mode transition stability criteria are satisfied. It shall be appreciated that the criterial illustrated in graphs 410 and 420 may be implemented in the systems and processes disclosed herein.
  • a graph 500 showing a diesel fueling control parameter 510 and a gaseous fueling control parameter 520 as a function of time.
  • diesel fueling control parameter 510 Prior to mode transition detected time 501 (which may be coincident with mode transition time 401) diesel fueling control parameter 510 varies based upon pre-transition diesel control criteria, for example, as described herein above.
  • diesel fueling control parameter 510 is set based on transition diesel control criteria, for example, as described herein above.
  • the transition control criteria hold diesel fueling control parameter 510 constant although other embodiments may vary diesel fueling control parameter 510.
  • mode stability criteria satisfied time 503 (which may be coincident with time 403) diesel fueling control parameter 510 varies based upon post-transition diesel control criteria, for example, as described herein.
  • gaseous fueling control parameter 520 Prior to mode transition detected time 501 gaseous fueling control parameter 520 varies based upon pre-transition gaseous control criteria, for example, as described herein above. Starting at mode transition detected time 501, gaseous fueling control parameter 520 is set based on transition gaseous control criteria, for example, as described herein above. In the illustrated embodiment the transition occurs at a constant slope although other embodiments may transition differently. After mode stability criteria satisfied time 503 (which may be coincident with time 403) gaseous fueling control parameter 510 varies based upon post-transition gaseous control criteria, for example, as described herein above. It shall be appreciated that the criterial illustrated in graph 500 may be implemented in the systems and processes disclosed herein.
  • One exemplary embodiment is method comprising: operating a dual fuel internal combustion engine system in a first combustion mode wherein the system combusts a first ratio of a liquid fuel and a gaseous fuel; transitioning operation of the system to a second combustion mode wherein the system combusts a second ratio of the liquid fuel and the gaseous fuel, the transitioning comprising: evaluating a mode transition condition, determining a final gas valve position, determining a transition gas valve position based upon the final gas valve position, adjusting a gas valve to the transition gas valve position at predetermined rate, operating the engine system based upon a predetermined transition table during adjustment of the gas valve to the transition gas valve position, once adjustment of the gas valve to the transition gas valve position is complete, utilizing a diesel governor to control engine speed to a target speed, and adjusting the gas valve to the final gas valve position based on one or more engine operating parameters.
  • the transitioning operation is effective to avoid engine knock, combustion misfire, and engine overspeed conditions resulting from an initial oversupply of gaseous fuel in combination with the standard amount of diesel fueling.
  • the first combustion mode is a diesel-only operating mode.
  • the liquid fuel is diesel fuel and the gaseous fuel is a gaseous hydrocarbon fuel.
  • the predetermined transition table is an infinite lambda table.
  • One exemplary embodiment is a method comprising: operating a dual fuel internal combustion engine system in a first combustion mode wherein the engine system combusts only diesel fuel; identifying a condition to transition from the first combustion mode; switching engine operation to a predetermined set of diesel injection control parameters configured for mode transition; opening a gaseous fuel control valve; as an operating condition of the system approaches a target operating condition, commencing a transition away from the predetermined set of diesel injection control parameters based on a predetermined stability criterion; and operating an internal combustion engine system in a second combustion mode wherein the engine system combusts a combination of diesel and gaseous fuel.
  • the predetermined set of diesel injection control parameters is represented by a three-dimensional response surface.
  • the three-dimensional response surface specifies at least one of diesel injection timing and injection pressure.
  • the opening a gaseous fuel control valve occurs at a predetermined rate.
  • the opening a gaseous fuel control valve includes abruptly moving the valve to a predetermined position.
  • the predetermined stability criterion includes at least one of an actual commanded diesel fueling quantity relative to a target desired fueling quantity and a sensed gas substitution rate relative to targeted gas substitution rate.
  • One exemplary embodiment is a system comprising: an internal combustion engine; a liquid fuel supply system; a gaseous fuel supply system; and a controller structured to control the internal combustion engine, the liquid fuel supply system and the gaseous fuel supply system to operate in a first combustion mode which combusts a first ratio of a liquid fuel from the liquid fuel supply system and gaseous fuel from the gaseous fuel supply system, and to transition operation of the system to a second combustion which combusts a second ratio of liquid fuel from the liquid fuel supply system and gaseous fuel from the gaseous fuel supply system; wherein the controller is structured to control the transition by evaluating a mode transition condition, determining a final gas valve position, determining a transition gas valve position based upon the final gas valve position, adjusting a gas valve to the transition gas valve position at predetermined rate, operating the engine system based upon a predetermined transition table during adjustment of the gas valve to the transition gas valve position, once adjustment of the gas valve to the transition gas valve position is complete, utilizing
  • the operation of the controller during the transition is effective to avoid engine knock, combustion misfire, and engine overspeed conditions resulting from an initial oversupply of gaseous fuel in combination with a standard amount of diesel fueling.
  • the first combustion mode is a diesel- only operating mode.
  • the liquid fuel is diesel fuel and the gaseous fuel is gaseous hydrocarbon.
  • the predetermined transition table is an infinite lambda table.
  • One exemplary embodiment is a system comprising: an internal combustion engine; a liquid fuel supply system; a gaseous fuel supply system; and a controller structured to control the internal combustion engine, the liquid fuel supply system and the gaseous fuel supply system to operate in a first combustion mode wherein the engine system combusts only diesel fuel, identify a condition to transition from the first combustion mode, switch engine operation to a predetermined set of diesel injection control parameters configured for mode transition, open a gaseous fuel control valve, as an operating condition of the system approaches a target operating condition, commence a transition away from the predetermined set of diesel injection control parameters based on a predetermined stability criterion, and operate in a second combustion mode wherein the engine system combusts a combination of diesel and gaseous fuel.
  • the predetermined set of diesel injection control parameters is represented by a three- dimensional response surface.
  • the three-dimensional response surface specifies at least one of diesel injection timing and injection pressure.
  • the opening a gaseous fuel control valve occurs at a predetermined rate.
  • the opening a gaseous fuel control valve includes abruptly moving the valve to a final/fixed position.
  • the predetermined stability criterion includes at least one of an actual commanded diesel fueling quantity relative to a target desired fueling quantity and a sensed gas substitution rate relative to targeted gas substitution rate.

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Abstract

The present application relates generally to combustion mode transition techniques, methods, apparatuses and systems for dual-fuel engines. Dual-fuel engines hold the promise of a number of potential economic and environmental benefits through the combustion of different ratios of two or more types of fuels during different modes of operation. For example, a dual-fuel engine may operate as a diesel engine during certain operating modes and may combust a variety of ratios of diesel fuel and gaseous fuel during other modes of operation. Transition between modes of operation in dual-fuel engines presents a unique set of technical challenges. A number of proposals have been made for controlling dual-fuel engines in multiple operating. Existing attempts to control dual-fuel engines in multiple fueling modes suffer from a number of drawbacks, problems and shortcomings. There remains a significant need for the unique controls techniques, methods, systems, and apparatuses disclosed herein.

Description

COMBUSTION MODE TRANSITION METHODS FOR DUAL-FUEL ENGINES
BACKGROUND
[0001] The present application relates generally to combustion mode transition techniques, methods, apparatuses and systems for dual-fuel engines. Dual-fuel engines hold the promise of a number of potential economic and environmental benefits through the combustion of different ratios of two or more types of fuels during different modes of operation. For example, a dual-fuel engine may operate as a diesel engine during certain operating modes and may combust a variety of ratios of diesel fuel and gaseous fuel during other modes of operation. Transition between modes of operation in dual-fuel engines presents a unique set of technical challenges. A number of proposals have been made for controlling dual-fuel engines in multiple operating. Existing attempts to control dual-fuel engines in multiple fueling modes suffer from a number of drawbacks, problems and shortcomings. There remains a significant need for the unique controls techniques, methods, systems, and apparatuses disclosed herein.
DISCLOSURE
[0002] For the purposes of clearly, concisely and exactly describing exemplary embodiments of the invention, the manner and process of making and using the same, and to enable the practice, making and use of the same, reference will now be made to certain exemplary embodiments, including those illustrated in the figures, and specific language will be used to describe the same. It shall nevertheless be understood that no limitation of the scope of the invention is thereby created, and that the invention includes and protects such alterations, modifications, and further applications of the exemplary embodiments as would occur to one skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] Fig. 1 illustrates an exemplary dual-fuel engine system.
[0004] Fig. 2 illustrates a flow diagram according to exemplary controls for a dual-fuel engine system.
[0005] Fig. 3 illustrates a flow diagram according to further exemplary controls for a dual-fuel engine system.
[0006] Fig. 4 illustrates graphs of mode transition and mode stability criteria satisfied values as functions of time.
[0007] Fig. 5 illustrates a graph of a diesel fueling control parameter and a gaseous fueling control parameter as a function of time.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0008] With reference to Fig. 1 there is illustrated an exemplary dual-fuel engine system
100 including an internal combustion engine 110, a diesel fueling system 120, an intake system 130, an exhaust system 140, and a controller 190. Diesel fueling system 120 is preferably configured as a high pressure common rail injection system which draws diesel fuel form a source 121, pressurizes diesel fuel with a pump 122 and provides pressurized diesel fuel to a common rail injection system 123 including a plurality of injectors configured to inject diesel fuel into the cylinders of engine 110. It shall be appreciated that diesel fueling system 120 is one example of a liquid fuelling system and that a variety of other liquid fuels and fueling systems may be utilized.
[0009] Intake system 130 includes an air filter 131 which receives and filters ambient air, a compressor 132 which compresses intake air, and an intake manifold 133 which provides intake air to the cylinders of engine 110. Intake system 130 further includes a gaseous fueling system 137 including a gaseous fuel supply 135 and a control valve system 134 including at least one valve configured to control the supply of gaseous fuel provided to the compressor 132.
Intake system 130 may include a mixer or other flow connection configured to mix air with the secondary fuel. The mixer may be positioned at a variety of locations in the intake system 130 including the illustrated position upstream of the compressor 132 as well as at the inlet to the compressor 132, at or after the outlet of compressor 132. Gaseous fuel could also be introduced into the intake manifold or intake ports. The intake system 130 may also include a charge air cooler, such as, for example, an air-to-air heat exchanger, an air-to-liquid heat exchanger, or a combination of both that facilitates the transfer of thermal energy to or from the charge flow.
[00010] Exhaust system 140 includes an exhaust manifold 143 which receives exhaust from the combustion cylinders of engine 110 and provides exhaust to a turbine 142 which is operatively couple with compressor 132. Exhaust system 140 further includes an aftertreatment system 141 configured to mitigate one or more exhaust constitutes. In an exemplary form the aftertreatment system includes a diesel oxidation catalyst (DOC), diesel particulate filter DPF, and selective catalytic reduction (SCR) catalyst. Other forms may include additional or alternate exhaust aftertreatment components as well as subsets of the foregoing components.
[00011] Controller 190 is operatively coupled with a plurality of other components and systems of engine system 100 and is configured to operate engine system 100 in a first mode which combusts a first ratio of diesel fuel and gaseous fuel, and a second mode which combusts a second ratio of diesel fuels and gaseous fuel. In a preferred form the first ratio comprises a diesel-only mode (e.g., a substantially 1 :0 ratio of diesel fuel to gaseous fuel), and the second ratio comprises a dual-fuel mode (e.g., an M:N ratio of diesel fuel to gaseous fuel greater than 1 :0). In the diesel only mode the engine 100 operates as a diesel engine and combusts only diesel fuel provided by diesel fueling system 120. In the dual-fuel mode, a supplementary gaseous fuel is added to the combustion cycle by gaseous fueling system 137. The supplementary gaseous fuel may be, for example, natural gas, bio-gas, methane, propane, ethanol, producer gas, field gas, liquefied natural gas (LNG), compressed natural gas (CNG), liquefied petroleum gas (LPG), or landfill gas. It shall be appreciated that gaseous fuel may be introduced via fumigation and/or port injection as well as via in-cylinder injection. In dual-fuel mode, the amount of diesel fuel combusted may be reduced according to the amount of gaseous fuel being introduced into the combustion cylinder.
[00012] Controller 190 may be configured to provide control commands that regulate the amount, timing, and duration of the first and secondary fuels provided to engine 1 10, the charge flow, and the exhaust flow to at least attempt for the engine system 100 to provide a desired torque and exhaust output. Accordingly, the controller 190 can be connected to various actuators, switches, sensors, or other devices associated with control of charge air flow, exhaust flow, and fueling amounts. For example, according to certain embodiments, the controller 190 may be in operable communication with one or more components and/or sensors associated with diesel fueling system 120 as well as gaseous fueling system 137. Controller 190 may further be connected with an intake throttle, an exhaust throttle, a compressor bypass, or a turbine geometry adjustment mechanism.
[00013] The controller 190 may also be operably connected to a variety of different sensors that detect and/or provide information relating to the operation of the engine system 100. For example, the controller 190 may be operably connected to a throttle sensor that detects the position of a throttle, an intake air temperature sensor, and exhaust temperature sensor, one or more after-treatment system sensors such as temperature sensors, lambda sensors, oxygen sensors, or NOx sensors.
[00014] In certain embodiments, the controller 190 is structured to form a portion of a processing system including one or more computing devices having memory, processing, and communication hardware in operative communication over one or more controller area network (CAN) systems. The controller 190 may be a single device or a distributed device, and the functions of the controller 190 may be performed by hardware or software. The controller 190 may be included within, partially included within, or completely separated from an engine controller (not shown). The controller 190 can also be in communication with any sensor or actuator throughout the systems disclosed herein, including through direct communication, communication over a datalink, and/or through communication with other controllers or portions of the processing subsystem that provide sensor and/or actuator information to the controller 190.
[00015] Controller 190 may be configured to transition between operating modes while maintaining acceptable performance, emissions, and mechanical limits. A number of methods for managing such transitions while avoiding engine knock, misfire, and transient emissions among other considerations are disclosed herein. Certain exemplary transition methods utilizes a transition mode operating table which is predetermined to avoid one or more predetermined operating events, such as engine knock, during a transition from a first combustion mode to a second combustion mode. In some forms the transition mode operating table may be utilized from a time at or after a gaseous fuel valve is opened to a time when the gaseous fuel valve achieves a final opened position at which time an alternate operating table may be used. In some forms the transition mode operating table may be utilized form a time at or after a gaseous fuel valve is opened to a time when the gaseous fuel valve achieves a transition opened position which is determined based upon a final opened position at which time an alternate control criteria may be used.
[00016] Certain exemplary transition methods comprise the following operations: (i) identify a need to change modes, (ii) determine final gas valve open position based on desired conditions, commands, or other criteria, (iii) determine transition gas valve open position (e.g., 90% of final) and lock on an infinite lambda table (e.g., a table constructed to control combustion assuming an infinite lambda value) until transition to 90% of final, (iv) open gas valve to transition position at predetermined rate, (v) once transition complete, allow diesel governor to manage engine speed to target speed, and (vi) achieve final gas valve open position based on engine operating parameters.
[00017] Certain exemplary transition methods include the following operations: (i) identify need (signal) to transition between modes, (ii) switch engine operation to a special set of diesel injection control parameters represented by a 3 -dimensional response surface (or another type of calibration table) specifying various parameters such as diesel injection timing, injection pressure, and multiple injection strategy (e.g. pilot, main, and/or post) wherein the table is designed in a manner to avoid engine knock, misfire, and other undesirable conditions, (iii) open a gaseous fuel control valve wherein the valve may be opened at a predetermined rate (time based), opened abruptly (single command) to a final/fixed position or opened based on other parameters (i.e. engine speed governor, diesel fueling quantity, measured or estimated gas substitution rate, vehicle or application load feedback, intake manifold pressure, intake manifold temperature, exhaust temperature, cylinder pressure, engine knock sensor, etc), and (iv) as the actual operating condition (speed & load) approaches the target operating condition, begin the transition away from the special set of diesel injection control parameters of operation (ii) based on a predetermined stability criteria wherein the stability criteria may include actual commanded diesel fueling quantity relative to target desired fueling quantity, and/or sensed gas substitution rate relative to targeted gas substitution rate.
[00018] Further details of several exemplary mode transition control techniques shall now be described. With reference to Fig. 2, there is illustrated a flow diagram of an exemplary control routine 200 which may be stored in a non-transitory controller readable memory medium and executed by controller 190 to control operation of a dual fuel engine system such as system 100 described herein or other types of dual fuel engine systems. Control routine 200 is initiated at operation 201 and proceeds to operation 210. Operation 210 computes diesel injection system control parameters based on pre-transition mode operating conditions. In certain exemplary embodiments operation 210 utilizes a set of multi-dimensional tables to determine diesel injection parameters based on engine speed and engine load. In a preferred form, operation 210 uses a set of three-dimensional response surfaces to determine timing and quantity values for a pre-injection, a main injection and a post-injection and a rail pressure value. The pre-transition mode diesel fueling parameters may be for a diesel-only operating mode or for a dual-fuel operating mode depending on the operating condition of engine system 100.
[00019] Operation 210 also computes gaseous fuel system control parameters based on pre-transition mode operating conditions. In certain exemplary embodiments operation 210 computes a valve position to provide a predetermined quantity of gaseous fuel and a charge flow parameter which may be controlled, for example, by controlling compressor boost pressure and/or intake throttle position. The pre-transition mode diesel fueling parameters may be for a diesel-only operating mode in which the valve is completely closed, or for a dual-fuel operating mode in which the valve opened depending on the operating condition of engine system 100. Operation 210 also monitors mode transition criteria for subsequent conditional evaluation.
[00020] From operation 210 process 200 proceeds to conditional 215 which evaluates whether a mode transition condition is detected. Conditional 215 may make this evaluation based upon a variety of criteria, for example, a mode transition command, an engine load, an engine speed, a commanded gaseous fuel substitution rate or a combination thereof. If conditional 215 determines that no mode transition is detected process 200 returns to operation to operation 210 and performs the operations described above. If conditional 215 determines that a mode transition is detected process 200 proceeds to operation to 220.
[00021] Operation to 220 determines target post-transition mode gaseous fuel system control parameters. In a preferred form these parameters include a valve position parameter and an intake charge flow parameter which provide a desired quantity of gaseous fuel once transition to a new operating mode is complete. Operation to 220 also determines transition mode gaseous fuel system control parameters as a function of the target post-transition mode control parameters. In a preferred form the transition mode gaseous fuel system control parameters are determined as a function of a predetermined percentage of the parameter values associated with the target post-transition mode conditions relative to the parameter values associated with the pre-transition mode conditions, and the parameter values associated with the pre-transition mode conditions. For example the transition mode gaseous fuel system control parameters may be determined in accordance with the following formula: TMGP = a*PTGP + b*(TPTGP/PTGP) where a and b are coefficients, TMGP is a transition mode gaseous fuel system control parameter, PTGP is the pre-transition gaseous fuel system control parameter, and TPTGP is the target post-transition gaseous fuel system control parameter. Other operating modes may operate according to one of more the following formulae: TMGP = a*PTGP - b*(TPTGP/PTGP), TMGP = b*(TPTGP/PTGP) - a*PTGP, TMGP = a*PTGP + b*(PTGP/ TPTGP), TMGP = a*PTGP - b*(PTGP/ TPTGP), or TMGP = b*(PTGP/ TPTGP) - a*PTGP.
[00022] From operation 220, control routine 200 proceeds to operation 230 which computes diesel injection system control parameters based on a transition mode specific operating table. The transition mode specific operating table provides a predetermined set of diesel injection control parameters represented by a three-dimensional response surface or other type of calibration table. The three-dimensional response surface specifies various calibratable parameters such as diesel injection timing, injection pressure, and multiple injection events (e.g., pilot, main, and/or post). The transition mode specific operating table is configured to avoid engine knock, misfire, and other undesirable conditions during transition. This may be accomplished, for example, by assuming that operation is occurring at a predetermined air to fuel ratio or a predetermined lambda value. In one form the three-dimensional response surface specifies calibratable parameters for an infinite lambda condition
[00023] Operation 230 also transitions computed gaseous fuel system control parameters from values determined from a pre-transition mode operating condition to a determined required transition value. In a preferred form operation 230 commands opening of a gaseous fuel control valve. The gaseous fuel control valve may be opened at a predetermined rate (e.g., time based), or may be opened abruptly (e.g., single command) to a final/fixed position. The gaseous fuel control valve may be opened based on various parameters (e.g., engine speed governor, diesel fueling quantity, measured or estimated gas substitution rate, vehicle or application load feedback, intake manifold pressure, intake manifold temperature, exhaust temperature, cylinder pressure, and/or engine knock sensor, to name several examples.)
[00024] From operation 230, control routine 200 proceeds to conditional 235 which evaluates whether gaseous fuel system control parameters are equal to required transition mode values. If conditional 235 evaluates no, process 200 returns to operation 230 and repeats the operations described above. If conditional 235 evaluates yes, process 200 proceeds to operation 240.
[00025] Operation 240 computes diesel injection system control parameters based on post- transition mode operating conditions. Operation 240 also computes gaseous fuel system control parameters based on post-transition operating conditions. From operation 240 process 200 proceeds to end state 299 it being appreciated that from end state 299, process 200 may repeat when called upon or after a predetermined time.
[00026] It shall be appreciated that the embodiment illustrated in Fig.2 will both avoid engine knock, combustion misfire, and an engine over speed condition resulting from an initial oversupply of gaseous fuel in combination with the standard amount of diesel fueling (i.e. engine over speed can occur if too much gaseous fuel is introduced before the diesel fueling has time to react (reduce) to the presence of the supplemental gas.
[00027] With reference to Fig. 3, there is illustrated a flow diagram of an exemplary control routine 300 which may be stored in a non-transitory controller readable memory medium and executed by controller 190 to control operation of a dual fuel engine system such as system 100 described herein or other types of dual fuel engine systems. Control routine 300 is initiated at operation 301 and proceeds to operation 310. Operation 310 computes diesel injection system control parameters based on pre-transition mode operating conditions. In certain exemplary embodiments operation 310 utilizes a set of multi-dimensional tables to determine diesel injection parameters based on engine speed and engine load. In a preferred form, operation 310 uses a set of three-dimensional response surfaces to determine timing and quantity values for a pre-injection, a main injection and a post-injection and a rail pressure value. The pre-transition mode diesel fueling parameters may be for a diesel-only operating mode or for a dual-fuel operating mode depending on the operating condition of engine system 100.
[00028] Operation 310 also computes gaseous fuel system control parameters based on pre-transition mode operating conditions. In certain exemplary embodiments operation 310 computes a valve position to provide a predetermined quantity of gaseous fuel and a charge flow parameter which may be controlled, for example, by controlling compressor boost pressure and/or intake throttle position. The pre-transition mode diesel fueling parameters may be for a diesel-only operating mode in which the valve is completely closed, or for a dual-fuel operating mode in which the valve opened depending on the operating condition of engine system 100. Operation 310 also monitors mode transition criteria for subsequent conditional evaluation.
[00029] From operation 310 process 300 proceeds to conditional 315 which evaluates whether a mode transition condition is detected. Conditional 315 may make this evaluation based upon a variety of criteria, for example, a mode transition command, an engine load, an engine speed, a commanded gaseous fuel substitution rate or a combination of the foregoing and/or other parameters. If conditional 315 determines that no mode transition is detected process 300 returns to operation to operation 310 and performs the operations described above. If conditional 315 determines that a mode transition is detected process 300 proceeds to operation to 320. [00030] Operation 320 computes diesel injection system control parameters based on a transition mode specific operating table. The transition mode specific operating table provides a predetermined set of diesel injection control parameters represented by a three-dimensional response surface or other type of calibration table. The three-dimensional response surface specifies various calibratable parameters such as diesel injection timing, injection pressure, and multiple injection strategy (e.g., pilot, main, and/or post). The transition mode specific operating table is configured to avoid engine knock, misfire, and other undesirable conditions during transition. This may be accomplished, for example, by assuming that operation is occurring at a predetermined air to fuel ratio or a predetermined lambda value. In one form the three- dimensional response surface specifies calibratable parameters for an infinite lambda condition.
[00031] Operation 320 also computes gaseous fuel system control parameters based on target post transition mode conditions. These parameters may be determined based on a desired quantity or substitution rate of gaseous fuel as well as a variety of other parameters. Operation 320 also monitors one or more mode stability criteria for subsequent evaluation. From operation 320 process 300 proceeds to conditional 325.
[00032] Conditional 325 evaluates whether one or more monitored mode stability criteria are satisfied. Exemplary mode stability criteria may include actual commanded diesel fueling quantity relative to target desired fueling quantity, and/or 2) sensed gas substitution rate relative to targeted gas substitution rate. If conditional 325 determines that the monitored mode stability criteria are not satisfied, process 300 returns to operation 320. If conditional 325 determines that the monitored mode stability criteria are satisfied, process 300 proceeds to operation 330.
[00033] Operation 330 transitions computed diesel injection parameters from values determined from the transition mode specific response surface to values determined from post- transition operating conditions. Operation 330 also computes gaseous fuel system control parameters based on post transition mode operating conditions. From operation 330 process 300 proceeds to end state 399 it being appreciated that from end state 399, process 300 may repeat when called upon or after a predetermined time.
[00034] With reference to Fig. 4 there are illustrated graphs 410 and 420. Graph 410 illustrates mode transition value as a function of time. Up to a transition time 401 the mode transition value has a logic value indicating no mode transition. At the transition time 401 the mode transition value transitions to a logic value indicating a mode transition. Graph 420 illustrates a mode transition stability criteria satisfied value as a function of time. Up to a stabilization time 403 subsequent to transition time 401 the mode transition stability criteria satisfied value has a logic value indicating that the mode transition stability criteria are not satisfied. After the stabilization time 403 the mode transition stability criteria satisfied value has a logic value indicating that the mode transition stability criteria are satisfied. It shall be appreciated that the criterial illustrated in graphs 410 and 420 may be implemented in the systems and processes disclosed herein.
[00035] With reference to Fig. 5 there is illustrated a graph 500 showing a diesel fueling control parameter 510 and a gaseous fueling control parameter 520 as a function of time. Prior to mode transition detected time 501 (which may be coincident with mode transition time 401) diesel fueling control parameter 510 varies based upon pre-transition diesel control criteria, for example, as described herein above. Starting at mode transition detected time 501, diesel fueling control parameter 510 is set based on transition diesel control criteria, for example, as described herein above. In the illustrated embodiment the transition control criteria hold diesel fueling control parameter 510 constant although other embodiments may vary diesel fueling control parameter 510. After mode stability criteria satisfied time 503 (which may be coincident with time 403) diesel fueling control parameter 510 varies based upon post-transition diesel control criteria, for example, as described herein.
[00036] Prior to mode transition detected time 501 gaseous fueling control parameter 520 varies based upon pre-transition gaseous control criteria, for example, as described herein above. Starting at mode transition detected time 501, gaseous fueling control parameter 520 is set based on transition gaseous control criteria, for example, as described herein above. In the illustrated embodiment the transition occurs at a constant slope although other embodiments may transition differently. After mode stability criteria satisfied time 503 (which may be coincident with time 403) gaseous fueling control parameter 510 varies based upon post-transition gaseous control criteria, for example, as described herein above. It shall be appreciated that the criterial illustrated in graph 500 may be implemented in the systems and processes disclosed herein.
[00037] A number of additional exemplary embodiments shall now be described. One exemplary embodiment is method comprising: operating a dual fuel internal combustion engine system in a first combustion mode wherein the system combusts a first ratio of a liquid fuel and a gaseous fuel; transitioning operation of the system to a second combustion mode wherein the system combusts a second ratio of the liquid fuel and the gaseous fuel, the transitioning comprising: evaluating a mode transition condition, determining a final gas valve position, determining a transition gas valve position based upon the final gas valve position, adjusting a gas valve to the transition gas valve position at predetermined rate, operating the engine system based upon a predetermined transition table during adjustment of the gas valve to the transition gas valve position, once adjustment of the gas valve to the transition gas valve position is complete, utilizing a diesel governor to control engine speed to a target speed, and adjusting the gas valve to the final gas valve position based on one or more engine operating parameters. In certain forms the transitioning operation is effective to avoid engine knock, combustion misfire, and engine overspeed conditions resulting from an initial oversupply of gaseous fuel in combination with the standard amount of diesel fueling. In certain forms the first combustion mode is a diesel-only operating mode. In certain forms wherein the liquid fuel is diesel fuel and the gaseous fuel is a gaseous hydrocarbon fuel. In certain forms the predetermined transition table is an infinite lambda table.
[00038] One exemplary embodiment is a method comprising: operating a dual fuel internal combustion engine system in a first combustion mode wherein the engine system combusts only diesel fuel; identifying a condition to transition from the first combustion mode; switching engine operation to a predetermined set of diesel injection control parameters configured for mode transition; opening a gaseous fuel control valve; as an operating condition of the system approaches a target operating condition, commencing a transition away from the predetermined set of diesel injection control parameters based on a predetermined stability criterion; and operating an internal combustion engine system in a second combustion mode wherein the engine system combusts a combination of diesel and gaseous fuel. In certain forms the predetermined set of diesel injection control parameters is represented by a three-dimensional response surface. In certain forms the three-dimensional response surface specifies at least one of diesel injection timing and injection pressure. In certain forms the opening a gaseous fuel control valve occurs at a predetermined rate. In certain forms the opening a gaseous fuel control valve includes abruptly moving the valve to a predetermined position. In certain forms the predetermined stability criterion includes at least one of an actual commanded diesel fueling quantity relative to a target desired fueling quantity and a sensed gas substitution rate relative to targeted gas substitution rate. [00039] One exemplary embodiment is a system comprising: an internal combustion engine; a liquid fuel supply system; a gaseous fuel supply system; and a controller structured to control the internal combustion engine, the liquid fuel supply system and the gaseous fuel supply system to operate in a first combustion mode which combusts a first ratio of a liquid fuel from the liquid fuel supply system and gaseous fuel from the gaseous fuel supply system, and to transition operation of the system to a second combustion which combusts a second ratio of liquid fuel from the liquid fuel supply system and gaseous fuel from the gaseous fuel supply system; wherein the controller is structured to control the transition by evaluating a mode transition condition, determining a final gas valve position, determining a transition gas valve position based upon the final gas valve position, adjusting a gas valve to the transition gas valve position at predetermined rate, operating the engine system based upon a predetermined transition table during adjustment of the gas valve to the transition gas valve position, once adjustment of the gas valve to the transition gas valve position is complete, utilizing a diesel governor to manage engine speed to a target speed, and adjusting the gas valve to the final gas valve position based on one or more engine operating parameters. In certain forms the operation of the controller during the transition is effective to avoid engine knock, combustion misfire, and engine overspeed conditions resulting from an initial oversupply of gaseous fuel in combination with a standard amount of diesel fueling. In certain forms the first combustion mode is a diesel- only operating mode. In certain forms the liquid fuel is diesel fuel and the gaseous fuel is gaseous hydrocarbon. In certain forms the predetermined transition table is an infinite lambda table.
[00040] One exemplary embodiment is a system comprising: an internal combustion engine; a liquid fuel supply system; a gaseous fuel supply system; and a controller structured to control the internal combustion engine, the liquid fuel supply system and the gaseous fuel supply system to operate in a first combustion mode wherein the engine system combusts only diesel fuel, identify a condition to transition from the first combustion mode, switch engine operation to a predetermined set of diesel injection control parameters configured for mode transition, open a gaseous fuel control valve, as an operating condition of the system approaches a target operating condition, commence a transition away from the predetermined set of diesel injection control parameters based on a predetermined stability criterion, and operate in a second combustion mode wherein the engine system combusts a combination of diesel and gaseous fuel. In certain forms the predetermined set of diesel injection control parameters is represented by a three- dimensional response surface. In certain forms the three-dimensional response surface specifies at least one of diesel injection timing and injection pressure. In certain forms the opening a gaseous fuel control valve occurs at a predetermined rate. In certain forms the opening a gaseous fuel control valve includes abruptly moving the valve to a final/fixed position. In certain forms the predetermined stability criterion includes at least one of an actual commanded diesel fueling quantity relative to a target desired fueling quantity and a sensed gas substitution rate relative to targeted gas substitution rate.
[00041] While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only certain exemplary embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as "a," "an," "at least one," or "at least one portion" are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language "at least a portion" and/or "a portion" is used the item can include a portion and/or the entire item unless specifically stated to the contrary.

Claims

1. A method comprising:
operating a dual fuel internal combustion engine system in a first combustion mode wherein the system combusts a first ratio of a liquid fuel and a gaseous fuel;
transitioning operation of the system to a second combustion mode wherein the system combusts a second ratio of the liquid fuel and the gaseous fuel, the transitioning comprising: evaluating a mode transition condition,
determining a final gas valve position,
determining a transition gas valve position based upon the final gas valve position, adjusting a gas valve to the transition gas valve position at predetermined rate, operating the engine system based upon a predetermined transition table during adjustment of the gas valve to the transition gas valve position,
once adjustment of the gas valve to the transition gas valve position is complete, utilizing a diesel governor to control engine speed to a target speed, and
adjusting the gas valve to the final gas valve position based on one or more engine operating parameters.
2. The method of claim 1 wherein the transitioning operation is effective to avoid engine knock, combustion misfire, and engine overspeed conditions resulting from an initial oversupply of gaseous fuel in combination with the standard amount of diesel fueling.
3. The method of claim 1 wherein the first combustion mode is a diesel-only operating mode.
4. The method of claim 1 wherein the liquid fuel is diesel fuel and the gaseous fuel is a gaseous hydrocarbon fuel.
5. The method of claim 1 wherein the predetermined transition table is an infinite lambda table.
6. A method comprising:
operating a dual fuel internal combustion engine system in a first combustion mode wherein the engine system combusts only diesel fuel;
identifying a condition to transition from the first combustion mode;
switching engine operation to a predetermined set of diesel injection control parameters configured for mode transition;
opening a gaseous fuel control valve;
as an operating condition of the system approaches a target operating condition, commencing a transition away from the predetermined set of diesel injection control parameters based on a predetermined stability criterion; and
operating an internal combustion engine system in a second combustion mode wherein the engine system combusts a combination of diesel and gaseous fuel.
7. The method of claim 6 wherein the predetermined set of diesel injection control parameters is represented by a three-dimensional response surface.
8. The method of claim 7 wherein the three-dimensional response surface specifies at least one of diesel injection timing and injection pressure.
9. The method of claim 6 wherein opening a gaseous fuel control valve occurs at a predetermined rate.
10. The method of claim 6 wherein opening a gaseous fuel control valve includes abruptly moving the valve to a predetermined position.
11. The method of claim 6 wherein the predetermined stability criterion includes at least one of an actual commanded diesel fueling quantity relative to a target desired fueling quantity and a sensed gas substitution rate relative to targeted gas substitution rate.
12. A system comprising:
an internal combustion engine; a liquid fuel supply system;
a gaseous fuel supply system; and
a controller structured to control the internal combustion engine, the liquid fuel supply system and the gaseous fuel supply system to operate in a first combustion mode which combusts a first ratio of a liquid fuel from the liquid fuel supply system and gaseous fuel from the gaseous fuel supply system, and to transition operation of the system to a second combustion which combusts a second ratio of liquid fuel from the liquid fuel supply system and gaseous fuel from the gaseous fuel supply system;
wherein the controller is structured to control the transition by evaluating a mode transition condition, determining a final gas valve position, determining a transition gas valve position based upon the final gas valve position, adjusting a gas valve to the transition gas valve position at predetermined rate, operating the engine system based upon a predetermined transition table during adjustment of the gas valve to the transition gas valve position, once adjustment of the gas valve to the transition gas valve position is complete, utilizing a diesel governor to manage engine speed to a target speed, and adjusting the gas valve to the final gas valve position based on one or more engine operating parameters.
13. The system of claim 12 wherein operation of the controller during the transition is effective to avoid engine knock, combustion misfire, and engine overspeed conditions resulting from an initial oversupply of gaseous fuel in combination with a standard amount of diesel fueling.
14. The system of claim 12 wherein the first combustion mode is a diesel-only operating mode.
15. The system of claim 12 wherein the liquid fuel is diesel fuel and the gaseous fuel is gaseous hydrocarbon.
16. The system of claim 12 wherein the predetermined transition table is an infinite lambda table.
17. A system comprising :
an internal combustion engine;
a liquid fuel supply system;
a gaseous fuel supply system; and
a controller structured to control the internal combustion engine, the liquid fuel supply system and the gaseous fuel supply system to operate in a first combustion mode wherein the engine system combusts only diesel fuel, identify a condition to transition from the first combustion mode, switch engine operation to a predetermined set of diesel injection control parameters configured for mode transition, open a gaseous fuel control valve, as an operating condition of the system approaches a target operating condition, commence a transition away from the predetermined set of diesel injection control parameters based on a predetermined stability criterion, and operate in a second combustion mode wherein the engine system combusts a combination of diesel and gaseous fuel.
18. The system of claim 17 wherein the predetermined set of diesel injection control parameters is represented by a three-dimensional response surface.
19. The system of claim 18 wherein the three-dimensional response surface specifies at least one of diesel injection timing and injection pressure.
20. The system of claim 17 wherein opening a gaseous fuel control valve occurs at a predetermined rate.
21. The system of claim 17 wherein opening a gaseous fuel control valve includes abruptly moving the valve to a final/fixed position.
22. The system of claim 17 wherein the predetermined stability criterion includes at least one of an actual commanded diesel fueling quantity relative to a target desired fueling quantity and a sensed gas substitution rate relative to targeted gas substitution rate.
PCT/US2015/037352 2014-06-24 2015-06-24 Combustion mode transition methods for dual-fuel engines WO2015200443A1 (en)

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