Post injection and spark timing control for spark ignition engines

Abstract

Systems, methods, and apparatuses are disclosed that determine, while the engine is operating with base fuel amount at an air-fuel ratio at or above an air-fuel ratio minimum limit, a post injection condition in response to one or more engine operating parameters. In response to the post injection condition being present, a main injection fuel amount and a post injection fuel amount for combustion in the one or more combustion chambers are determined that, when combined, is at or above the air-to-fuel ratio minimum limit. A main spark timing and, if needed, a post spark timing to fully combust the main and post injection fuel amounts in the combustion chamber are also determined.

Description

Atty Docket No. CMI002-00135 / 23-0550-SRC POST INJECTION AND SPARK TIMING CONTROL FOR SPARK IGNITION ENGINES CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims the benefit of the filing date of, and priority to,U.S. Provisional Application Ser. No. 63 / 619,517 filed on January 10, 2024, which is incorporated herein by reference. FIELD OF THE INVENTION

[0002] The present application is related to internal combustion engines, and moreparticularly to post injection and spark timing control of lean burn spark ignition internal combustion engines. BACKGROUND

[0003] Mitigation of nitrogen oxides (NOx) generated during operation of internalcombustion engines, including, for example, lean burn spark ignited engines, remains to be of particular importance. One technique for mitigating NOx generation during combustion is to maintain the air-to-fuel ratio above a predetermined minimum threshold. However, during certain operating conditions, such as during a transient condition in which an increased torque response is quickly needed from the internal combustion engine, maintaining the air-to-fuel ratio above the predetermined minimum threshold can negatively impact the engine’s ability to achieve the desired torque response. Therefore, further improvements in this technological area are needed.Atty Docket No. CMI002-00135 / 23-0550-SRC SUMMARY

[0004] The present application includes systems, methods, and apparatuses that determine,a post injection condition in response to one or more engine operating parameters while a lean burn spark ignited internal combustion engine is operating with an air-fuel ratio at or above an air-fuel ratio minimum limit. The internal combustion engine nominally operates using a base fuel amount and spark timing in one or more combustion chambers. In response to the post injection condition being present, such as an engine transient, a main injection fuel amount and a post injection fuel amount for combustion in the one or more combustion chambers are determined that, when combined, is at or above the air-to-fuel ratio minimum limit. A main spark timing and, if needed, a post spark timing, are determined to provide spark(s) that fully combust the main and post injection fuel amounts in the combustion chamber. As a result, less work is extracted from the fuel by the piston, and more energy is sent to the exhaust to produce a positive airflow response from the turbocharger to improve engine performance using post injection fuel amounts without producing fuel slip into the exhaust or aftertreatment.

[0005] This summary is not intended to identify key or essential features of the claimedsubject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.Atty Docket No. CMI002-00135 / 23-0550-SRC BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The description herein makes reference to the accompanying figures wherein likereference numerals refer to like parts throughout the several views.

[0007] FIG. 1 illustrates a schematic block diagram of an exemplary internal combustionengine system that includes a lean burn spark ignition internal combustion engine.

[0008] FIG. 2 illustrates a block diagram of certain components of an exemplary controllerused to control certain operations of components of the engine system of FIG.1.

[0009] FIG. 3 illustrates a flow diagram of an exemplary process of operation of the enginesystem of FIG.1 to provide a post injection fuel amount for combustion with a main injection fuel amount.

[0010] The foregoing summary, as well as the following detailed description of certainembodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, certain embodiments. It should be understood, however, that the present invention is not limited to the arrangements and instrumentalities shown in the attached drawings. Further, like numbers in the respective figures indicate like or comparable parts.Atty Docket No. CMI002-00135 / 23-0550-SRC DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0011] Certain terminology is used in the foregoing description for convenience and is notintended to be limiting. Words such as “upper,” “lower,” “top,” “bottom,” “first,” and “second” designate directions in the drawings to which reference is made. This terminology includes the words specifically noted above, derivatives thereof, and words of similar import. Additionally, the words “a” and “one” are defined as including one or more of the referenced item unless specifically noted. The phrase “at least one of” followed by a list of two or more items, such as “A, B or C,” means any individual one of A, B or C, as well as any combination thereof.

[0012] Embodiments of the present application include a control strategy and method thatcan improve lean burn spark ignited internal combustion engine performance to better respond to transient conditions while maintaining an air-fuel ratio above a NOx mitigation-related air-fuel ratio minimum limit. A post injection fuel amount is determined for injection in addition to a main injection fuel amount that are both fully combusted during the engine cycle and are controlled to not violate the air-fuel ratio minimum limit. Embodiments of the present application can also be configured to determine a post spark timing that is provided in addition to a main spark timing if needed to combust the post injection fuel amount. The post injection fuel amount and combustion timing re-directs combustion energy to the exhaust flow to improve turbine response.

[0013] FIG. 1 illustrates a schematic block diagram of an exemplary internal combustionengine system 100 that includes a lean burn spark ignition internal combustion engine 102 that is connected to an intake 104 and an exhaust 106. It shall be appreciated that the illustrated configuration and components of the engine system 100 are but one example, and that the disclosure contemplates that a variety of different engine systems and the associated components may be utilized. Further, the engine system 100 may be used in a variety of different applications or platforms, and moreover with a variety of different types of machines, vehicles, and / or devices, including, but not limited to, stationary devices as well as on-road vehicles, including automotive applications.

[0014] Engine 102 can receive fuel from one or more fuel sources 108. Further, while theillustrated embodiment may generally depict an engine system 100 used with lean burn spark ignition engine applications, the engine system 100 can be structured to operate with a variety of types of fuels that are delivered from the fuel source 108, including, for example, gaseous fuels such as hydrogen, natural gas, bio-gas, methane, propane, gasoline, ethanol, producer gas, field gas,Atty Docket No. CMI002-00135 / 23-0550-SRC liquefied natural gas, compressed natural gas, landfill gas, gaseous fuel, and / or any combination thereof, among other fuels.

[0015] According to the exemplary embodiment, the engine 102 includes an engine blockthat may define at least a portion of one or more cylinders 110. For example, according to certain embodiments, the engine 102 can include six cylinders 110 in an in-line arrangement as illustrated in FIG. 1. However, the engine 102 may have any different number of cylinders 110, as well as cylinders in a variety of different arrangements. Additionally, each cylinder 110 is sized to accommodate the slideable displacement of a piston (not shown) along at least a portion of the cylinder 110 such that the pistons may reciprocate between a top-dead-center position and a bottom-dead-center position. Each of the cylinders 110, its respective piston and cylinder head, form a combustion chamber. Further, at least a portion of the forces generated by the slideable displacement of the piston along at least a portion of the cylinder during combustion events in the combustion chamber are transmitted to a mechanical drive system (not shown.) For example, the pistons are typically operably coupled to a crank shaft of the engine system 100 that converts the reciprocal movement of the pistons of the engine 102 into rotational movement.

[0016] The cylinders 110 are in selective fluid communication with the intake 104 suchthat a charged air flow can be delivered to the combustion chamber. The cylinders 110 are also in selective fluid communication with the exhaust 106 such that exhaust gases produced by combustion of fuel(s) in the combustion chambers can be delivered through an exhaust manifold 112 of the exhaust 106. The exhaust 106 can include and / or be coupled to a variety of different components, such as, for example, one or more turbines 114a of turbocharger 114, as well as an aftertreatment system 116. Engine system 100 may also include an exhaust gas recirculation system (not shown), such as a high pressure and / or a low pressure exhaust gas recirculation system.

[0017] Operation of fuel injection events can include the delivery of charge flow and fuelto the combustion chambers of the engine 102. According to certain embodiments, gaseous fuel can be injected into each cylinder 110 via a corresponding one of the injectors 120. Other embodiments contemplate gaseous fuel is fumigated into the charge flow upstream of the cylinders 110 of engine 102, such as, for example, upstream or downstream of the compressor 114b of turbocharger 144 at intake 104, at the intake manifold 118, and / or cylinder ports, or can be fumigated into the charge mixture in-cylinder. Combustion of the air-fuel mixture can be initiated with igniters 122, such as spark plugs, that create a spark at each of the cylinders 110. The deliveryAtty Docket No. CMI002-00135 / 23-0550-SRC of the charge mixture, the fuel, and / or the ignition of the charge and fuel mixture in the combustion chambers may be, at least in part, electrically controlled by an electronic control system 130 of the engine system 100, as discussed further below.

[0018] In an embodiment, engine 102 includes pistons that reciprocate in thecorresponding cylinders 110 during a four stroke cycle in which a crankshaft rotates 720 degrees per cycle. The term “four stroke” herein means the following four strokes – intake, compression, power, and exhaust – that the piston completes during two separate revolutions of the engine’s crankshaft, which is a combustion cycle. A stroke begins either at a top dead center (TDC) when the piston is at the top of cylinder, or at a bottom dead center (BDC), when the piston has reached its lowest point in the cylinder.

[0019] During the intake stroke, the piston descends away from cylinder head above thecombustion chamber of the cylinder 110 to a bottom (not shown) of the cylinder 110, thereby reducing the pressure in the combustion chamber. A combustion charge is created in the combustion chamber by an intake of a charge from intake 104 through intake ports when the intake valves are opened.

[0020] During the compression stroke in a nominal or standard mode of operation, theintake valves and the exhaust valves are closed. The piston returns toward TDC and fuel is injected near TDC in an injection event, and the compressed fuel-air mixture ignites in the combustion chamber after a short delay. The ignition of the air and fuel causes a rapid increase in pressure in the combustion chamber, which is applied to the piston during its power stroke toward the BDC. Combustion phasing in combustion chamber is calibrated so that the increase in pressure in combustion chamber pushes the piston, providing a net positive in the force / work / power of the piston to rotate the crankshaft.

[0021] As discussed further below, during certain operating conditions of engine 102,the base fuel amount determined for injection during the injection event is separated into a main injection event and a post injection event that follows the main injection event. The base fuel amount can be proportionally allocated between the main injection event and post injection event, and / or the post injection event can be augmented with additional fuel, provided the air- fuel ratio minimum limit is not violated. The fuel provided during the post injection event is timed so that its combustion during the current combustion cycle provides lessAtty Docket No. CMI002-00135 / 23-0550-SRC force / work / power to the piston and more energy is directed to the exhaust 106 to increase turbine output.

[0022] During the exhaust stroke, the piston is returned toward TDC while the exhaustvalves are open. This action discharges the burnt products of the combustion of the fuel in the combustion chamber and expels the spent fuel-air mixture (exhaust gas) out through the exhaust valves into exhaust 106. The next combustion cycle occurs using these same intake and exhaust valve opening closing profiles, unless a cylinder deactivation condition or alternative valve lift condition is employed.

[0023] The control system 130 can include an electronic controller or electronic controlunit (ECU) 132 that can be configured to control various operational aspects of engine system 100, including fuel injection events and spark events, among other operations. The electronic controller 132 can be implemented in a number of ways. Further, the electronic controller 132 can execute operating logic that defines various control, management, and / or regulation functions. The operating logic may be in the form of one or more microcontroller or microprocessor routines stored in a non-transitory memory, dedicated hardware, such as a hardwired state machine, analog calculating machine, various types of programming instructions, and / or other forms as would occur to those skilled in the art.

[0024] The controller 132 may be provided as a single component, or a collection ofoperatively coupled components, and may comprise digital circuitry, analog circuitry, or a hybrid combination of both of these types. When of a multi-component form, the controller 132 may have one or more components remotely located relative to the others in a distributed arrangement. The controller 132 can include multiple processing units arranged to operate independently, in a pipeline processing arrangement, in a parallel processing arrangement, or the like. In one embodiment, the controller 132 includes several programmable microprocessing units of a solid- state, integrated circuit type that are distributed throughout the engine system 100 that each includes one or more processing units and non-transitory memory.

[0025] For the depicted embodiment, the controller 132 includes a computer networkinterface to facilitate communications using standard Controller Area Network (CAN) communications or the like among various system control units. It should be appreciated that the depicted modules or other organizational units of the controller 132 refer to certain operating logic performing indicated operations that may each be implemented in a physically separate controllerAtty Docket No. CMI002-00135 / 23-0550-SRC of the controller 132 and / or may be virtually implemented in the same controller. Controller 132 may include one or more organizational units or circuits that may be implemented in hardware and / or as computer instructions on a non-transient computer readable storage medium, and may be distributed across various hardware or computer based components.

[0026] Example and non-limiting implementation elements of control system 130 and / ororganizational units of the controller 132 include, for example, sensors such as intake sensors 134, engine sensors 136, exhaust sensors 138, and / or other sensors providing any value determined herein, sensors providing any value that is a precursor to a value determined herein, datalink and / or network hardware including communication chips, oscillating crystals, communication links, cables, twisted pair wiring, coaxial wiring, shielded wiring, transmitters, receivers, and / or transceivers, logic circuits, hard-wired logic circuits, reconfigurable logic circuits in a particular non-transient state configured according to the module specification, any actuator including at least an electrical, hydraulic, or pneumatic actuator, a solenoid, an op-amp, analog control elements (springs, filters, integrators, adders, dividers, gain elements), and / or digital control elements. Sensors 134, 136, 138 and / or any other sensors may be physical sensors, virtual sensors, and / or combinations of physical and virtual sensors.

[0027] The controller 132 and / or any of its constituent processors / controllers may includeone or more signal conditioners, modulators, demodulators, Arithmetic Logic Units (ALUs), Central Processing Units (CPUs), limiters, oscillators, control clocks, amplifiers, signal conditioners, filters, format converters, communication ports, clamps, delay devices, memory devices, Analog to Digital (A / D) converters, Digital to Analog (D / A) converters, and / or different circuitry or functional components as would occur to those skilled in the art to perform the desired communications.

[0028] Referencing FIG. 2, according to certain embodiments, electronic controller 132includes a base fuel amount determination circuit 140, a post injection determination circuit 142, a main and post fuel coordination circuit 144, and a spark and fuel injection timing circuit 146. The circuits 140, 142, 144, 146 operate to determine an amount and timing of one or more injections of fuel into cylinders 110, and one or more spark timings to fully combust the delivered fuel during the current combustion cycle to prevent fuel slip into the exhaust,

[0029] Base fuel amount determination circuit 140 receives a number of air-fuel ratio(AFR) related inputs 148 that are used to determine and output a base fuel amount (Wfuel) to mainAtty Docket No. CMI002-00135 / 23-0550-SRC and post fuel coordination circuit 146. AFR inputs 148 can be, for example, an average lambda (λ) or AFR, a minimum lambda or AFR, an intake air flow rate or amount (Wair), a requested torque output, an engine speed, a current gear, and other parameters that might be used in determining a base fuel amount for injection into cylinders 110 to operate engine 102. The base fuel amount can be determined by calculation, look-up tables, models, etc.

[0030] Post injection determination circuit 142 receives a number of post injection inputs150, determines whether post injection operations are enabled, and outputs a post injection fuel amount (Wfuel,post) and post injection ratio (Xpost-fuel,ratio) in response to post injection operation being enabled. Post injection determination circuit 142 also determines a spark timing (STpost), a start-of- injection (SOIpost) and an end-of-injection (EOIpost) timing for the post injection fuel amount, if needed, to fully combust the post injection fuel amount during the current engine cycle. In an embodiment, post injection determination circuit 142 includes enable post injection logic 152, post injection ratio / quantity determination logic 154, post injection timing logic 156, and post spark timing logic 158.

[0031] Post injection inputs 150 include, for example, an engine speed, an engine torque, abase fuel amount, a lambda, an exhaust temperature, and other operating conditions of engine 102. Enable post injection logic 152 determines if engine operating conditions indicate a post injection condition is present, such as a current or upcoming transient for engine 102. Operating conditions indicative of a transient event can include, for example, depression of an input device requesting an increase in engine output such as an accelerator tip-in event, a threshold increase in load applied to engine 102, a threshold increase in power demanded from engine 102, and / or a threshold increase in torque in an output shaft connected to engine 102. In addition or alternatively, one or more sensors connected to controller 132 can be operable to provide operating signals indicating one or more operating parameters or conditions of engine 102 that indicate a current or predicted transient event.

[0032] Post injection ratio / quantity determination logic 154 determines post injection fuelamount (Wfuel,post) and post injection ratio (Xpost-fuel,ratio) in response to post injection operation being enabled. The post injection fuel amount (Wfuel,post) can be determined based on the desired amount of energy from the base fuel amount to transfer from the piston to the exhaust output. The post injection ratio is determined by dividing post injection fuel amount by the base fuel amount.

[0033] Xpost-injection = Wfuel,post / Wfuel Equation 1Atty Docket No. CMI002-00135 / 23-0550-SRC

[0034] Post injection ratio / quantity determination logic 154, post injection timing logic156, and post spark timing logic 158 can be configured to determine the post injection fuel amount along with spark timing (STpost), the start-of-injection (SOIpost) timing and the end-of-injection (EOIpost) for the post injection fuel amount (Wfuel,post) that provides the energy amount in the exhaust flow that produces the desired or more desirable turbocharger response to the transient condition.

[0035] Main and post fuel coordination circuit 144 receives inputs of the post injection fuelamount (Wfuel,post) and post injection ratio (Xpost-injection) from post injection determination circuit 142 and the base fuel amount (Wfuel) from base fuel amount determination circuit 140. Main and post fuel coordination circuit 144 determines a main injection fuel amount (Wfuel,main), a post injection fuel amount (Wfuel,post), and a total fuel injection amount (Wfuel,total) as the sum of the main injection fuel amount W(fuel,main) and the post injection fuel amount (Wfuel,post) subject to the AFR minimum limit so that NOx mitigation control is maintained, as discussed further below.

[0036] Spark and fuel injection timing circuit 146 determines a main spark timing (STmain),a start-of-injection (SOImain) and an end-of-injection (EOImain) for the base fuel amount. These outputs are combined with the outputs from post injection determination circuit 142 to provide spark timing, SOI, and EOI control for main injection fuel amount and post injection fuel amount.

[0037] Referring back to main and post fuel coordination circuit 144, the main injectionfuel amount (Wfuel,main), the determination of the post injection fuel amount (Wfuel,post), and the total fuel injection amount (Wfuel,total) can vary based on the actual AFR in comparison with the AFR minimum limit. In a first example, if actual AFR is at the AFR minimum limit, the base fuel amount is split proportionally between the main injection fuel amount and the post injection fuel amount. In this scenario, the corresponding fuel amounts are determined as follows:

[0038] ^^^^^^^^^^,^^^^^^^^ = (1 − ^^^^^^^^^^−^^^^^^^^^^^^^^^^^^) ^^^^^^^^^^ Equation 2

[0039] ^^^^^^^^ Equation 3

[0040] over the AFR minimum limit, thepost injection fuel amount can be determined a number of ways. In a second example, post injection fuel amount (Wfuel,post) can be provided as an addition to the base fuel amount (Wfuel) determined by base fuel amount determination circuit 140 as follows:

[0041] ^^^^^^^^^^,^^^^^^^^ = ^^^^^^^^^^ Equation 4

[0042] ^^^^^^^^^^,^^^^^^^^^^ = ^^^^^^^^^^,^^^^^^^^ + ^^^^^^^^^^,^^^^^^^^ Equation 5Atty Docket No. CMI002-00135 / 23-0550-SRC

[0043] In a third example, with actual AFR sufficiently above the AFR minimum limit,post injection fuel amount (Wfuel,post) can be determined from the post injection ratio and proportionally allocated as follows:

[0044] ^^^^^^^^^^,^^^^^^^^ = ^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Equation 6

[0045] = − ^^^^^^^^^^ Equation 7

[0046] = = ^^^^^^^^ Equation 8

[0047] above the AFR minimum limit,post injection can a combination of the previous two examples. The main injection fuel amount (Wfuel,main) and the post injection fuel amount (Wfuel,post) are determined by splitting fuel from AFR control, and excess fuel (Δ) available that is less than an air-fuel ratio minimum limit fuel amount is added to the post injection fuel amount in the same post-injection event, as follows:

[0048] ^^^^^^^^^^,^^^^^^^^ = ^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + Δ Equation 9

[0049] + ^^^^^^^^^^, ^^^^^^^^ Equation 10

[0050] for the post injection fuelamount (Wfuel,post,max) is used to prevent total fueling from violating the AFR minimum limit. This can be calculated as follows, where Wair is the intake air flow amount, λmin is the minimum lambda, and AFRstoichis the stoichiometric air fuel ratio:

[0051] ^^^^^^^^^^^^^^^^^^,^^^^^^^^,^^^^^^ =^^^^^^^^× ^^^^^^^^^^^^^^^^ℎ−^^^^^^^^^^Equation 11

[0052] post-injection timing, a second sparkcommand can be used at an appropriate timing to burn excess fuel injected by the post injection fuel amount. This ensures all fuel is combusted to produce energy for driving the turbine 114a and fuel does not slip to the exhaust 106 and / or aftertreatment 116.

[0053] Referring to FIG. 3, a schematic flow diagram of a procedure 300 is provided.Procedure 300 determines an amount and timing of one or more injections of fuel into cylinders 110, and one or more spark timings to fully combust the delivered fuel during the current combustion cycle to prevent fuel slip into the exhaust.

[0054] Procedure 300 starts at 302, and continues at operation 304 to monitor engineoperating parameters while operating engine 102. Procedure 300 continues at conditional 306 to determine if a post injection condition is present from the one or more operating parameters. IfAtty Docket No. CMI002-00135 / 23-0550-SRC conditional 306 is negative, procedure 300 returns to operation 304. If conditional 306 is affirmative, a post injection condition is present and procedure 300 continues at operation 308.

[0055] In an embodiment, conditional 306 is affirmative when the one or more operatingparameters indicate a transient condition for engine 102 is present. Other embodiments contemplate that other operating states of engine 102 indicated by the operating parameters may indicate a post injection condition.

[0056] At operation 308, procedure 300 determines a post injection fuel amount. The postinjection fuel amount is for injection into the combustion chamber of a cylinder 110 of engine 102 during the combustion cycle for the combustion chamber.

[0057] At operation 310, procedure 300 determines a main injection fuel amount. Themain injection fuel amount is for injection into the combustion chamber of the cylinder 110 before injection of the post injection fuel amount. A sum of the main injection fuel amount and post injection fuel amount is limited by an air-fuel ratio minimum limit for NOx mitigation.

[0058] At operation 312, procedure 300 determines a start-of-injection (SOI) and end-of-injection (EOI) for each of the main injection fuel amount and the post injection fuel amount. At operation 314, a spark timing is determined that fully combusts the main injection fuel amount and the post injection fuel amount during the combustion cycle. In an embodiment, a second or post spark timing is provided to produce a second spark for the post injection fuel amount combustion.

[0059] In an embodiment of procedure 300, the post injection fuel amount, the start ofpost injection and the end of post injection timing for the post injection fuel amount, and the spark timing to combust the post injection fuel amount during the combustion cycle is determined based on engine speed, engine torque, an exhaust temperature, a base fuel amount to the internal combustion engine 102 determined by a closed loop air-fuel ratio control, and an air-fuel ratio to the internal combustion engine 102.

[0060] In an embodiment, procedure 300 includes determining a base fuel amount inresponse to a closed loop air-fuel ratio control. The base fuel amount is equal to or less than an air-fuel ratio limit fuel amount. The base fuel amount is an amount of fuel injected into the combustion chamber in the absence of the post injection condition.

[0061] In an embodiment of procedure 300, in response to the base fuel amount equalingthe air-fuel ratio limit fuel amount, procedure 300 includes determining a post injection ratio of the post injection fuel amount to the base fuel amount. The base fuel amount is proportionallyAtty Docket No. CMI002-00135 / 23-0550-SRC allocated between the main injection fuel amount and the post injection fuel amount based on the post injection ratio so that a total fuel injection amount for injection during the combustion cycle is equal to the base fuel amount.

[0062] In an embodiment of procedure 300, in response to the base fuel amount beingless than the air-fuel ratio limit fuel amount, procedure 300 includes determining the main injection fuel amount is equal to the base fuel amount. A total fuel injection amount for injection during the combustion cycle is a sum of the main injection fuel amount and the post injection fuel amount.

[0063] In an embodiment of procedure 300, in response to the base fuel amount beingless than the air-fuel ratio limit fuel amount, procedure 300 includes determining a post injection ratio of the post injection fuel amount to the base fuel amount. The base fuel amount is proportionally allocated between the main injection fuel amount and the post injection fuel amount based on the post injection ratio so that a total fuel injection amount is equal to the base fuel amount.

[0064] In an embodiment of procedure 300, in response to the base fuel amount beingless the air-fuel ratio limit fuel amount, procedure 300 includes determining a post injection ratio from the post injection fuel amount to the base fuel amount. The base fuel amount is proportionally allocated to the main injection fuel amount based on the post injection ratio. An excess fuel amount corresponding to the difference between the base fuel amount and the air- fuel ratio limit fuel amount is added to the post injection fuel amount.

[0065] In each of the embodiments, the total fuel injection amount is limited by the air-fuel ratio limit fuel amount. For example, the post injection fuel amount can be limited based on a difference between the air-fuel ratio limit fuel amount and the base fuel amount.

[0066] Various aspects of the present disclosure are contemplated. For example,according to one aspect a system for controlling combustion in an internal combustion engine is provided. The system includes an electronic controller configured to determine a post injection condition for the internal combustion engine is present in response to one or more engine operating parameters; determine, based at least in part on the post injection condition: a post injection fuel amount for injection into a combustion chamber of the internal combustion engine during a combustion cycle for the combustion chamber, and a main injection fuel amount for injection into the combustion chamber before injection of the post injection fuel amount, whereAtty Docket No. CMI002-00135 / 23-0550-SRC a sum of the main injection fuel amount and post injection fuel amount is limited by an air-fuel ratio minimum limit; determine a start of main injection timing and an end of main injection timing for the main injection fuel amount; determine a start of post injection timing and an end of post injection timing for the post injection fuel amount; and determine a spark timing to combust each of the main injection fuel amount and the post injection fuel amount during the combustion cycle.

[0067] In an embodiment, the electronic controller is configured to determine the sparktiming to include a main spark timing to combust the main injection fuel amount and a post spark timing to ignite the post injection fuel amount.

[0068] In an embodiment, the electronic controller is configured to determine a base fuelamount in response to a closed loop air-fuel ratio control, the base fuel amount being equal to or less than an air-fuel ratio limit fuel amount.

[0069] In a further embodiment, the base fuel amount is an amount of fuel injected intothe combustion chamber in the absence of the post injection condition.

[0070] In a further embodiment, in response to the base fuel amount equaling the air-fuel ratio limit fuel amount, the electronic controller is configured to determine a post injection ratio from the post injection fuel amount and the base fuel amount and proportionally allocate the base fuel amount between the main injection fuel amount and the post injection fuel amount based on the post injection ratio so that a total fuel injection amount is equal to the base fuel amount.

[0071] In a further embodiment, in response to the base fuel amount being less than theair-fuel ratio limit fuel amount, the electronic controller is configured to determine the main injection fuel amount is equal to the base fuel amount and that a total fuel injection amount is a sum of the main injection fuel amount and the post injection fuel amount.

[0072] In yet a further embodiment, the controller is configured to limit the postinjection fuel amount based on a difference between the air-fuel ratio limit fuel amount and the base fuel amount.

[0073] In a further embodiment, in response to the base fuel amount being less than theair-fuel ratio limit fuel amount, the electronic controller is configured to: determine a post injection ratio from the post injection fuel amount and the base fuel amount; and proportionally allocate the base fuel amount between the main injection fuel amount and the post injection fuelAtty Docket No. CMI002-00135 / 23-0550-SRC amount based on the post injection ratio so that a total fuel injection amount is equal to the base fuel amount.

[0074] In a further embodiment, in response to the base fuel amount being less than theair-fuel ratio limit fuel amount, the electronic controller is configured to: determine a post injection ratio from the post injection fuel amount and the base fuel amount; proportionally allocate the base fuel amount to the main injection fuel amount based on the post injection ratio; and adding an excess fuel amount corresponding to a difference between the base fuel amount and the air-fuel ratio limit amount to the post injection fuel amount.

[0075] In yet a further embodiment, the controller is configured to limit the postinjection fuel amount based on a difference between the air-fuel ratio limit fuel amount and the base fuel amount.

[0076] In an embodiment, the electronic controller is configured to determine the postinjection condition is present in response to a transient operating condition of the internal combustion engine.

[0077] In an embodiment, the electronic controller is configured to determine the postinjection fuel amount, the start of post injection and the end of post injection timing for the post injection fuel amount, and the spark timing to combust the post injection fuel amount during the combustion cycle based on engine speed, engine torque, an exhaust temperature, a base fuel amount to the internal combustion engine determined by a closed loop air-fuel ratio control, and an air-fuel ratio to the internal combustion engine.

[0078] In an embodiment, the system includes an internal combustion engine. Theinternal combustion engine includes a plurality of cylinders for receiving an intake air flow and fuel, a plurality of spark plug associated with respective ones of the plurality of cylinders, and a turbocharger that compresses the intake air flow using exhaust produced by combustion in the plurality of cylinders.

[0079] According to another aspect, a method for controlling combustion in an internalcombustion engine is provided. The method includes determining a post injection condition for the internal combustion engine is present in response to one or more engine operating parameters; determining, based at least in part on the post injection condition: a post injection fuel amount for injection into a combustion chamber of the internal combustion engine during a combustion cycle for the combustion chamber and a main injection fuel amount for injectionAtty Docket No. CMI002-00135 / 23-0550-SRC into the combustion chamber before injection of the post injection fuel amount, where a sum of the main injection fuel amount and post injection fuel amount is limited by an air-fuel ratio minimum limit; determining a start of main injection timing and an end of main injection timing for the main injection fuel amount; determining a start of post injection timing and an end of post injection timing for the post injection fuel amount; and determining a spark timing to combust each of the main injection fuel amount and the post injection fuel amount during the combustion cycle.

[0080] In an embodiment, determining the spark timing includes determining a mainspark timing to combust the main injection fuel amount and a post spark timing to ignite the post injection fuel amount.

[0081] In an embodiment, the method includes determining a base fuel amount inresponse to a closed loop air-fuel ratio control. The base fuel amount is equal to or less than an air-fuel ratio limit fuel amount, and the base fuel amount is an amount of fuel injected into the combustion chamber in the absence of the post injection condition.

[0082] In a further embodiment, in response to the base fuel amount equaling the air-fuel ratio limit fuel amount, the method include determining a post injection ratio from the post injection fuel amount and the base fuel amount, and proportionally allocating the base fuel amount between the main injection fuel amount and the post injection fuel amount based on the post injection ratio so that a total fuel injection amount is equal to the base fuel amount.

[0083] In a further embodiment, in response to the base fuel amount being less than theair-fuel ratio limit fuel amount, the method includes determining the main injection fuel amount is equal to the base fuel amount and that a total fuel injection amount is a sum of the main injection fuel amount and the post injection fuel amount.

[0084] In a further embodiment, in response to the base fuel amount being less than theair-fuel ratio limit fuel amount, the method includes determining a post injection ratio from the post injection fuel amount and the base fuel amount, and proportionally allocating the base fuel amount between the main injection fuel amount and the post injection fuel amount based on the post injection ratio so that a total fuel injection amount is equal to the base fuel amount.

[0085] In a further embodiment, in response to the base fuel amount being less than theair-fuel ratio limit fuel amount, the method includes determining a post injection ratio from the post injection fuel amount and the base fuel amount; proportionally allocating the base fuelAtty Docket No. CMI002-00135 / 23-0550-SRC amount to the main injection fuel amount based on the post injection ratio; and adding an excess fuel amount corresponding to a difference between the base fuel amount and the air-fuel ratio limit fuel amount to the post injection fuel amount.

[0086] In an embodiment, the post injection condition is present in response to atransient operating condition of the internal combustion engine.

[0087] In an embodiment, the post injection fuel amount, the start of post injection andthe end of post injection timing for the post injection fuel amount, and the spark timing to combust the post injection fuel amount during the combustion cycle is determined based on engine speed, engine torque, an exhaust temperature, a base fuel amount to the internal combustion engine determined by a closed loop air-fuel ratio control, and an air-fuel ratio to the internal combustion engine.

[0088] While the invention has been described in connection with what is presentlyconsidered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that 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” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and / or “a portion” is used the item may include a portion and / or the entire item unless specifically stated to the contrary.

Claims

Atty Docket No. CMI002-00135 / 23-0550-SRC WHAT IS CLAIMED IS:

1. A system for controlling combustion in an internal combustion engine, the system comprising: an electronic controller configured to: determine a post injection condition for the internal combustion engine is present in response to one or more engine operating parameters; determine, based at least in part on the post injection condition: a post injection fuel amount for injection into a combustion chamber of the internal combustion engine during a combustion cycle for the combustion chamber; and a main injection fuel amount for injection into the combustion chamber before injection of the post injection fuel amount, wherein a sum of the main injection fuel amount and post injection fuel amount is limited by an air-fuel ratio minimum limit; determine a start of main injection timing and an end of main injection timing for the main injection fuel amount; determine a start of post injection timing and an end of post injection timing for the post injection fuel amount; and determine a spark timing to combust each of the main injection fuel amount and the post injection fuel amount during the combustion cycle.

2. The system of claim 1, wherein the electronic controller is configured to determine the spark timing to include a main spark timing to combust the main injection fuel amount and a post spark timing to ignite the post injection fuel amount.

3. The system of claim 1, wherein the electronic controller is configured to determine a base fuel amount in response to a closed loop air-fuel ratio control, the base fuel amount being equal to or less than an air-fuel ratio limit fuel amount.

4. The system of claim 3, wherein the base fuel amount is an amount of fuel injected into the combustion chamber in the absence of the post injection condition.Atty Docket No. CMI002-00135 / 23-0550-SRC 5. The system of claim 3, wherein, in response to the base fuel amount equaling the air-fuel ratio limit fuel amount, the electronic controller is configured to: determine a post injection ratio from the post injection fuel amount and the base fuel amount; and proportionally allocate the base fuel amount between the main injection fuel amount and the post injection fuel amount based on the post injection ratio so that a total fuel injection amount is equal to the base fuel amount.

6. The system of claim 3, wherein, in response to the base fuel amount being less than the air-fuel ratio limit fuel amount, the electronic controller is configured to determine the main injection fuel amount is equal to the base fuel amount and that a total fuel injection amount is a sum of the main injection fuel amount and the post injection fuel amount.

7. The system of claim 6, wherein the controller is configured to limit the post injection fuel amount based on a difference between the air-fuel ratio limit fuel amount and the base fuel amount.

8. The system of claim 3, wherein, in response to the base fuel amount being less than the air-fuel ratio limit fuel amount, the electronic controller is configured to: determine a post injection ratio from the post injection fuel amount and the base fuel amount; and proportionally allocate the base fuel amount between the main injection fuel amount and the post injection fuel amount based on the post injection ratio so that a total fuel injection amount is equal to the base fuel amount.

9. The system of claim 3, wherein, in response to the base fuel amount being less than the air-fuel ratio limit fuel amount, the electronic controller is configured to: determine a post injection ratio from the post injection fuel amount and the base fuel amount; proportionally allocate the base fuel amount to the main injection fuel amount based on the post injection ratio; andAtty Docket No. CMI002-00135 / 23-0550-SRC adding an excess fuel amount corresponding to a difference between the base fuel amount and the air-fuel ratio limit amount to the post injection fuel amount.

10. The system of claim 9, wherein the controller is configured to limit the post injection fuel amount based on a difference between the air-fuel ratio limit fuel amount and the base fuel amount.

11. The system of claim 1, wherein the electronic controller is configured to determine the post injection condition is present in response to a transient operating condition of the internal combustion engine.

12. The system of claim 1, wherein the electronic controller is configured to determine the post injection fuel amount, the start of post injection and the end of post injection timing for the post injection fuel amount, and the spark timing to combust the post injection fuel amount during the combustion cycle based on engine speed, engine torque, an exhaust temperature, a base fuel amount to the internal combustion engine determined by a closed loop air-fuel ratio control, and an air-fuel ratio to the internal combustion engine.

13. The system of claim 1, further comprising the internal combustion engine, the internal combustion engine including: a plurality of cylinders for receiving an intake air flow and fuel; a plurality of spark plug associated with respective ones of the plurality of cylinders; and a turbocharger that compresses the intake air flow using exhaust produced by combustion in the plurality of cylinders.

14. A method for controlling combustion in an internal combustion engine, the method comprising: determining a post injection condition for the internal combustion engine is present in response to one or more engine operating parameters; determining, based at least in part on the post injection condition:Atty Docket No. CMI002-00135 / 23-0550-SRC a post injection fuel amount for injection into a combustion chamber of the internal combustion engine during a combustion cycle for the combustion chamber; and a main injection fuel amount for injection into the combustion chamber before injection of the post injection fuel amount, wherein a sum of the main injection fuel amount and post injection fuel amount is limited by an air-fuel ratio minimum limit; determining a start of main injection timing and an end of main injection timing for the main injection fuel amount; determining a start of post injection timing and an end of post injection timing for the post injection fuel amount; and determining a spark timing to combust each of the main injection fuel amount and the post injection fuel amount during the combustion cycle.

15. The method of claim 14, wherein determining the spark timing includes determining a main spark timing to combust the main injection fuel amount and a post spark timing to ignite the post injection fuel amount.

16. The method of claim 14, further comprising determining a base fuel amount in response to a closed loop air-fuel ratio control, the base fuel amount being equal to or less than an air-fuel ratio limit fuel amount, and the base fuel amount is an amount of fuel injected into the combustion chamber in the absence of the post injection condition.

17. The method of claim 16, wherein, in response to the base fuel amount equaling the air- fuel ratio limit fuel amount, the method includes: determining a post injection ratio from the post injection fuel amount and the base fuel amount; and proportionally allocating the base fuel amount between the main injection fuel amount and the post injection fuel amount based on the post injection ratio so that a total fuel injection amount is equal to the base fuel amount.

18. The method of claim 16, wherein, in response to the base fuel amount being less than the air-fuel ratio limit fuel amount, the method includes:Atty Docket No. CMI002-00135 / 23-0550-SRC determining the main injection fuel amount is equal to the base fuel amount and that a total fuel injection amount is a sum of the main injection fuel amount and the post injection fuel amount.

19. The method of claim 16, wherein, in response to the base fuel amount being less than the air-fuel ratio limit fuel amount, the method includes: determining a post injection ratio from the post injection fuel amount and the base fuel amount; and proportionally allocating the base fuel amount between the main injection fuel amount and the post injection fuel amount based on the post injection ratio so that a total fuel injection amount is equal to the base fuel amount.

20. The method of claim 16, wherein, in response to the base fuel amount being less than the air-fuel ratio limit fuel amount, the method includes: determining a post injection ratio from the post injection fuel amount and the base fuel amount; proportionally allocating the base fuel amount to the main injection fuel amount based on the post injection ratio; and adding an excess fuel amount corresponding to a difference between the base fuel amount and the air-fuel ratio limit fuel amount to the post injection fuel amount.

21. The method of claim 14, wherein the post injection condition is present in response to a transient operating condition of the internal combustion engine.

22. The method of claim 14, wherein the post injection fuel amount, the start of post injection and the end of post injection timing for the post injection fuel amount, and the spark timing to combust the post injection fuel amount during the combustion cycle is determined based on engine speed, engine torque, an exhaust temperature, a base fuel amount to the internal combustion engine determined by a closed loop air-fuel ratio control, and an air-fuel ratio to the internal combustion engine.

Images