Combustion control to prevent knock and pre-ignition during transients in spark-ignited internal combustion engines

Abstract

Combustion control to prevent knock and pre-ignition during transients in a spark-ignition internal combustion engine is provided. Systems, methods, and apparatus are disclosed for determining a spark timing correction for an internal combustion engine during a transient event. Spark timing correction retards spark timing to reduce or mitigate knock. The spark timing correction is based on a Lambda difference between a steady state Lambda based on engine speed and engine torque and a feedback Lambda from operation of the engine. The feedback Lambda may be based on the calculated Lambda or the sensed Lambda.

Description

TECHNICAL FIELD

[0001] The present application relates to internal combustion engines, and more particularly to combustion control for preventing knock and pre-ignition during transients in a spark-ignition internal combustion engine. BACKGROUND

[0002] Mitigating knock and pre-ignition during operation of internal combustion engines, including for example, spark-ignition internal combustion engines, remains particularly important. During transient conditions, the risk of knock is increased due to the need to increase fueling, which results in a low transient lambda. Conventional techniques are to respond to knock detection by retarding spark timing after increasing fueling to mitigate knock occurrence. However, since fueling is increased prior to retarding spark timing, the risk of knock occurrence is increased. In addition, spark timing retard also increases the risk of pre-ignition. Therefore, further improvements in this technical field are needed. SUMMARY

[0003] The present application includes systems, methods, and apparatuses for determining and implementing a spark timing correction during a transient event in a spark-ignition internal combustion engine. The internal combustion engine nominally or normally operates with a steady-state lambda (also referred to as air-to-fuel ratio) and a steady-state spark timing in one or more combustion chambers. During a transient event, the steady-state or base fueling is increased to an end fueling to the engine, which lowers the air-to-fuel ratio (lambda), creating a spark timing correction condition. A spark timing correction is then determined based on a lambda difference between the steady-state lambda and a feedback lambda, which is sensed by an oxygen sensor and / or calculated from the end fueling and charge flow to the engine. The spark timing correction retards the steady-state spark timing based on the lambda difference to reduce the risk of knock while increasing the transient response torque capability of the internal combustion engine.

[0004] This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in limiting the scope of the claimed subject matter. Additional implementations, forms, objects, advantages, aspects, features, benefits, and the like will become apparent to those of ordinary skill in the art from the description and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0005] The description herein makes reference to the accompanying drawings, which illustrate several implementations, forms, objects, advantages, aspects, features, benefits, and the like. The drawings are for illustrative purposes only, and are not intended to limit the scope of the inventive subject matter in any way.

[0006] Figure 1 A schematic block diagram of an exemplary internal combustion engine system including a spark-ignition internal combustion engine and an electronic controller is shown.

[0007] Figure 2 A block diagram of certain components of an exemplary electronic controller for controlling an internal combustion engine in response to a transient event is shown. Figure 1certain spark timing operations of components of engine systems.

[0008] Figure 3 is a graphical illustration of the relationship of spark timing to lambda, depicting exemplary knock, pre-ignition, and normal combustion regions, as well as exemplary adjustments of steady state spark timing and steady state lambda in response to transient events.

[0009] FIG. 4 illustrates Figure 1 is a flowchart of an exemplary operational process of an internal combustion engine system providing spark timing adjustments in response to transient events.

[0010] The foregoing summary, as well as the following detailed description of certain embodiments of the present application, will be better understood when read in conjunction with the accompanying drawings, as are claimed. For the purposes of illustrating the present application, certain examples are shown in the drawings. However, it is understood that the present application is not limited to the arrangements and instrumentalities shown in the attached figures. Additionally, like reference numerals in the various drawings are intended to represent the same or similar parts. DETAILED DESCRIPTION

[0011] Certain terms are used throughout the above description in order to describe the application more completely. However, such terms are used only in context to facilitate discussion of the illustrative embodiments of the application and are not intended to limit the application. Words such as "upper," "lower," "top," "bottom," "first," and "second" designate directions in the drawings to which reference is made. Such terminology includes the words specifically mentioned 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 indicated otherwise. The phrase "and / or," following use of a list of two or more items, covers all of the following interpretations of the word "and": any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0012] Embodiments of the present application include a control strategy and method that can improve spark-ignited internal combustion engine performance to better respond to transient conditions while mitigating or reducing knock and pre-ignition. Spark timing adjustments are made to retard spark timing during transients to reduce or mitigate knock. In one embodiment, spark timing is adjusted based on a lambda difference between a sensed or calculated feedback lambda from an end fuel quantity to the engine and a steady state lambda. Embodiments of the present application can also be configured to reduce or mitigate pre-ignition by restoring spark timing when lambda exceeds a desired threshold. Embodiments of the present application can also allow spark timing adjustments to be performed in real-time in conjunction with lambda changes provided in response to transient events.

[0013] Figure 1A schematic block diagram of an exemplary internal combustion engine system 100 is shown, which includes a spark-ignition internal combustion engine 102 connected to an intake port 104 and an exhaust port 106. It should be understood that the illustrated configuration and components of engine system 100 are merely an example, and this disclosure contemplates the use of various different engine systems and associated components. Furthermore, engine system 100 can be used in a variety of different applications or platforms, and also in various types of machines, vehicles, and / or devices, including but not limited to stationary installations and road vehicles (including automotive applications).

[0014] Engine 102 may receive fuel from one or more fuel sources 108. Furthermore, while the illustrated embodiments generally depict engine system 100 for spark-ignition engine applications, engine system 100 may be configured to operate using various types of fuel supplied from fuel source 108, including, for example, gaseous fuels such as hydrogen, natural gas, biogas, methane, propane, gasoline, ethanol, producer gas, oilfield gas, liquefied natural gas, compressed natural gas, landfill gas, gaseous fuels and / or any combination thereof, as well as other fuels. In a particular embodiment, engine 102 is a spark-ignition internal combustion engine that burns hydrogen fuel, which is supplied to the combustion chamber of engine 102 in an amount based on engine speed and engine torque and corresponding to the air-fuel ratio or λ.

[0015] According to an exemplary embodiment, engine 102 includes an engine block that defines at least a portion of one or more cylinders 110. For example, according to some embodiments, engine 102 may include, for instance, […]. Figure 1 The diagram shows six cylinders 110 arranged in a straight line. However, the engine 102 can have any different number of cylinders 110, and various different arrangements of cylinders. Furthermore, each cylinder 110 is sized to accommodate the sliding displacement of a piston (not shown) along at least a portion of the cylinder 110, allowing the piston to reciprocate between top dead center and bottom dead center positions. Each cylinder 110, its corresponding piston, and cylinder head form a combustion chamber. Moreover, during combustion events in the combustion chamber, at least a portion of the force generated by the piston's sliding displacement along at least a portion of the cylinder is transmitted to a mechanical drive system (not shown). For example, the piston is typically operatively coupled to the crankshaft of the engine system 100, which converts the reciprocating motion of the piston of the engine 102 into rotational movement.

[0016] The cylinders 110 are in selective fluid communication with the intake port 104 such that a charge flow from the intake port 104 can be delivered to the combustion chamber. The cylinders 110 are also in selective fluid communication with the exhaust port 106 such that exhaust gases produced by combustion of fuel in the combustion chamber can be delivered through an exhaust manifold 112 of the exhaust port 106. The exhaust port 106 can include and / or be coupled to various different components such as, for example, one or more turbines 114a of a turbocharger 114, and an aftertreatment system 116. The engine system 100 can also include an exhaust gas recirculation system (not shown) such as a high pressure and / or low pressure exhaust gas recirculation system. However, embodiments without a turbocharger and / or exhaust gas recirculation system are also contemplated.

[0017] Operation of the engine 102 can include delivering a charge flow and fuel to the combustion chamber of the engine 102. According to certain embodiments, fuel such as hydrogen gas can be injected into each cylinder 110 via a respective one of the injectors 120. Other embodiments contemplate gaseous fuel being fumigated into the charge flow upstream of the cylinders 110 of the engine 102 at the intake port 104, at the intake manifold 118, and / or at cylinder ports, such as, for example, upstream or downstream of the compressor 114b of the turbocharger 144, or can be fumigated into the charge mixture within the cylinder. Combustion of the air-fuel mixture can be initiated by an igniter 122 such as a spark plug that generates a spark at each of the cylinders 110. As discussed further below, delivery of the charge mixture, fuel, and / or ignition of the charge and fuel mixture in the combustion chamber can be at least partially electrically controlled by an electronic control system 130 of the engine system 100.

[0018] In one embodiment, the engine 102 includes a piston that reciprocates in a respective cylinder 110 during a four-stroke cycle in which the crankshaft rotates 720 degrees per cycle. The term "four-stroke" herein means the four strokes— intake, compression, power, and exhaust— that a piston completes during two separate rotations of the engine crankshaft, which is one combustion cycle. A stroke begins at top dead center (TDC) when the piston is at the top of the cylinder, or at bottom dead center (BDC) when the piston reaches its lowest point in the cylinder.

[0019] During the intake stroke, the piston descends away from the cylinder head over the combustion chamber of the cylinder 110 to the bottom of the cylinder 110 (not shown), thereby reducing the pressure in the combustion chamber. As the intake valve opens, charge is drawn in from the intake port 104 through the intake port, creating a combustion charge in the combustion chamber.

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

[0021] As discussed further below, during a transient event of the engine 102, the control system 130 is configured to determine an increase in the amount of base fuel injected during an injection event in response to the transient event. At the same time, one of the calculated lambda and the sensed lambda of the engine 102 is used as a feedback lambda to determine a lambda difference from the steady-state lambda based on engine speed and engine torque. A spark timing adjustment to the steady-state spark timing is then determined for the transient event based on the lambda difference. The spark timing adjustment delays the spark timing during the transient event to reduce or mitigate the likelihood of knock during the transient event due to a reduced lambda value. Since the spark timing adjustment is based on the lambda difference, the spark timing is delayed without the need to detect or sense the presence of knock.

[0022] The control system 130 includes an electronic controller or electronic control unit (ECU) 132 configured to control various operational aspects of the engine system 100, including fuel injection events and spark timing events, among other operations. The electronic controller 132 can be implemented in a variety of ways. Moreover, the electronic controller 132 can execute operational logic defining various control, management, and / or regulation functions. The operational logic can be in the form of one or more microcontroller or microprocessor routines stored in non-transitory memory, special-purpose hardware such as a hardwired state machine, analog computer machinery, various types of programmed instructions, and / or other forms as will occur to those skilled in the art.

[0023] The electronic controller 132 can be provided as a single component or a collection of components operably coupled, and can include digital circuitry, analog circuitry, or a hybrid combination of the two types. When having a multi-component form, the electronic controller 132 can have one or more components remotely located in a distributed arrangement relative to other components. The electronic controller 132 can include multiple processing units arranged to operate independently in a pipelined processing arrangement, a parallel processing arrangement, and the like. In one embodiment, the electronic controller 132 includes several programmable microprocessor units of the solid-state integrated circuit type distributed throughout the internal combustion engine system 100, each including one or more processing units and non-transitory memory.

[0024] For the depicted embodiment, the electronic controller 132 includes a computer network interface to facilitate communication between various system control units using standard controller area network (CAN) communications or the like. It will be appreciated that the depicted modules or other organizational units of the electronic controller 132 refer to certain operational logic that performs the indicated operations, which can each be implemented in physically separate controllers of the electronic controller 132 and / or can be implemented virtually in the same controller. The electronic controller 132 can include one or more organizational units or circuits, which can be implemented in hardware and / or as computer instructions on a non-transitory computer readable storage medium, and which can be distributed across various hardware or computer-based components.

[0025] Exemplary and non-limiting implementation elements of the control system 130 and / or the organizational units of the electronic controller 132 include, for example, sensors such as the charge flow sensor 134, engine sensors 136 such as speed, torque, and / or fuel sensors, oxygen sensors 138, and / or other sensors that provide any of the values determined herein, sensors that provide any values that are antecedents of values determined herein; data link and / or network hardware including communication chips, oscillating crystals, communication links, cables, twisted pair wires, coaxial wires, shielded wires, transmitters, receivers, and / or transceivers; logic circuits; hardwired logic circuits; reconfigurable logic circuits in a particular non-transitory state configured according to a module specification; any actuators including at least electrical, hydraulic, or pneumatic actuators; solenoids; operational amplifiers; analog control elements (springs, filters, integrators, adders, dividers, gain elements); and / or digital control elements. The sensors 134, 136, 138, and / or any other sensors can be physical sensors, virtual sensors, and / or a combination of physical and virtual sensors.

[0026] The electronic controller 132 and / or any constituent processors / controllers thereof can include one 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, clamping circuits, delay devices, memory devices, analog-to-digital (A / D) converters, digital-to-analog (D / A) converters, and / or different circuits or functional components as would occur to those skilled in the art for performing the desired communications.

[0027] With reference to Figure 2According to certain embodiments, the electronic controller 132 includes a fuel quantity determination circuit 140, a lambda evaluation circuit 142, and a spark timing determination circuit 144. The circuits 140, 142, 144 operate in conjunction to determine a fuel injection quantity into the cylinder 110 of the engine 102, a lambda parameter related to the fuel injection, and a spark timing to mitigate knock and pre-ignition during transient events of the engine 102. In one embodiment, the electronic controller 132 is configured to determine a spark timing correction in real-time in conjunction with a change in fueling of the internal combustion engine in response to a transient event. In one embodiment, the electronic controller 132 is configured to determine the spark timing correction without sensing knock and / or without detecting the presence of knock.

[0028] The fuel quantity determination circuit 140 outputs a reference fuel quantity (fuel ref ) from a desired fueling table 150. The desired fueling table 150 can be any suitable look-up table, such as a table that provides a target fuel quantity or a reference fuel quantity based on engine speed and engine load. Embodiments contemplate determining the reference fuel quantity from a look-up table, a model, a calculation, etc.

[0029] The fuel determination circuit 140 receives the reference fuel quantity (fuel ref ) from the desired fueling table 150 at a fuel limiter 152. The fuel limiter 152 also receives a transient lambda limit (lambda ref,tr ) 162 from the lambda evaluation circuit 142, as discussed further below. The fuel limiter 152 evaluates the reference fuel quantity (fuel ref ) and the transient lambda limit (lambda ref,tr ) to output a final fuel quantity (fuel final ) that is used to fuel the engine 102 during the transient event.

[0030] The lambda evaluation circuit 142 includes operational logic 160 that can include, for example, a first logic that determines a fixed lambda limit for a transient event. The operational logic 160 can also include a second logic that determines an intelligent lambda limit for a transient event, such as from a look-up table. The fixed lambda limit and / or the intelligent lambda limit are provided to a transient lambda limiter 162. The transient lambda limiter 162 also receives a feedback lambda (lambda fdbk ) 168 from at least one of two sources. One source is a calculated lambda (lambda calc ), and the second source is a sensed lambda (lambda O2sen ) from the oxygen sensor 138. The transient lambda limiter 162 evaluates the feedback lambda (lambda fdbk ) 168 in conjunction with the fixed lambda limit and the intelligent lambda limit to output the transient lambda limit (lambda ref,tr ) 162 that is evaluated by the fuel limiter 152.

[0031] The lambda evaluation circuit 142 also includes a steady state lambda lookup table 164 for determining the steady state lambda (λ ref,ss ) for engine speed and engine torque. The difference between the steady state lambda (λ ref,ss ) and the feedback lambda (λ fdbk ) is determined at an arithmetizer 166. The determined lambda difference (λ diff ) is output to the spark timing determination circuit 144. The lambda difference (λ diff ) provides an indication of the amount of reduction in lambda needed in response to a transient event.

[0032] The spark timing determination circuit 144 includes a steady state spark timing lookup table 170 for determining the steady state reference spark timing (ST ref,ss ) for engine speed and engine torque. The steady state reference spark timing (ST ref,ss ) and the lambda difference (λ diff ) are provided to a spark timing correction calculator 172. The spark timing correction calculator 172 determines a spark timing correction velocity relative to the steady state reference spark timing using the following equation:

[0033]

[0034] Coeffl and Coeff2 are coefficients determined from a one-dimensional table calibrated using transient response testing to determine spark timing adjustments that will reduce or mitigate knock at various engine speeds. In addition, the lambda difference (λ diff ) can also be substituted for (λ fdbk - λ ref，ss ). The corrected spark timing (ST corr ) is output by the spark timing correction calculator 172, which is evaluated by a spark timing limiter 174 to apply any upper or lower adjustment limit to the corrected spark timing (ST corr ). The spark timing limiter 174 outputs the transient spark timing (ST ref,tr ) to the engine 102. The transient spark timing (ST ref,tr ) is used during transient events in conjunction with the final fuel quantity to reduce or mitigate knock.

[0035] In one embodiment, the spark timing correction calculator 172 evaluates the derivative of the lambda difference (λ diff ) to compensate for any delay in obtaining the lambda measurement. Other embodiments contemplate other techniques to process and / or evaluate the lambda difference (λ diff ) to determine the spark timing correction or adjustment.

[0036] Reference is made to Figure 3, the graph 300 shows an example spark timing adjustment for a transient event. The graph 300 plots spark timing along the X-axis and lambda along the Y-axis. The graph 300 also bounds a knock region 302, an early fire region 304, a combined knock and early fire region 306, and a normal region 308 that is not affected by knock and / or early fire. A steady state operating point 310 indicates a steady state spark timing and a steady state lambda.

[0037] In response to a transient event, the controller 132 configured as described above is operable to retard spark timing in real time while lowering the lambda floor to increase richness, providing more fuel to respond to the transient event. As a result of the spark timing retard, the risk of knock is reduced and there is more room to intentionally lower the lambda floor to inject more fuel to obtain better torque response. An adjustment path 312 extending from the steady state operating point 310 to a transient operating point 314 indicates a decrease in lambda and the associated spark timing retard. By contrast, a conventional approach only responds to a transient event when lambda falls into the knock region, as indicated by lambda value adjustment 316, and then retards spark timing when knock is detected by a knock sensor, as indicated by spark timing adjustment 318.

[0038] The method according to the present disclosure provides a spark timing adjustment, the transient spark timing (ST ref,tr ) discussed above, that takes effect before knock occurs to reduce or mitigate any knock that can occur during the transient event. Once the transient event is over, the controller 132 allows a quick return to the steady state spark timing at operating point 310 to reduce or mitigate early fire, as indicated by return path 320.

[0039] Referring to FIG. 4, an embodiment of a control procedure 400 for determining a spark timing adjustment that results in a transient spark timing (ST ref,tr ) is disclosed. The control procedure 400 includes an input signal evaluation routine 402, a lambda feedback routine 404, and a spark timing correction routine 406. The lambda feedback routine 404 determines a feedback lambda (λ fdbk ) 442 and provides it to the spark timing correction routine 406. The lambda feedback routine 404 enables the spark timing correction routine 406 only when the feedback lambda (λ fdbk ) 442 is less than a calibrated lambda value.

[0040] The spark timing correction from the enabled spark timing correction routine 406, also referred to as an incremental spark timing 408 in FIG. 4, is summed at a summation operation 410 with a steady state reference spark timing (ST ref,ss) are added. The upper and lower spark timing adjustment limits are applied to the output from the summation operation 410 at a limiter operation 412, such as discussed above with respect to the spark timing limiter 174. The spark timing output 414 from the limiter operation 412 corresponds to the transient spark timing (ST ref,tr ), which is provided to the engine 102 to retard spark timing in response to a transient event.

[0041] The input signal evaluation routine 402 receives and outputs various signals that are used to determine various values in the process of determining corrected spark timing or transient spark timing (ST ref,tr ). For example, the oxygen sensor 138 provides a sensed oxygen amount output that is used to determine a sensed lambda output λ_02 420 (λ O2sen ). The input signal evaluation routine 402 also receives a charge flow input 421 from the charge flow sensor 134 and a total fuel supply input 422 from the engine sensors 136. The inputs 421, 422 are evaluated at a stoichiometric delivery function 423 to determine a calculated lambda output λ_cal 424 (λ calc ). The outputs 420, 424 are provided to a condition 440 of the lambda feedback routine 404, as discussed further below.

[0042] The input signal evaluation routine 402 also receives an engine speed input 426 and an engine torque input 428 from the engine sensors 136. The engine speed input 426 and torque input 428 are used for a steady state lambda reference table lookup operation 430 and a steady state spark timing table lookup operation 434. The steady state lambda reference table lookup operation 430 provides a steady state lambda reference 432 (λ ref,ss ) for use by the spark timing correction routine 406. The steady state spark timing table lookup operation 434 provides a steady state spark timing reference 436 (ST ref,ss ).

[0043] The lambda feedback routine 404 receives the sensed lambda output λ_02 420 (λ O2sen ) and the calculated lambda output λ_cal 424 (λ calc ) at a condition 440. The condition 440 evaluates the outputs 420 and / or 424 and determines a feedback λ_fdbk output 442 (λ fdbk ). The feedback λ_fdbk output 442 (λ fdbk ) is provided to a difference calculation operation 460 of the spark timing correction routine 406 and a first condition 444 of the lambda feedback routine.

[0044] The feedback λ_fdbk output 442 (λ fdbk) to ensure that spark timing adjustment does not occur when the fuel supply to the engine 102 is too lean. If the first condition 444 is "yes," the spark timing correction routine 406 is enabled. If the first condition 444 is "no," the feedback λ fdbk output 442 (λ fdbk ) is evaluated at a second condition 446 to determine if it is between a first λ threshold and a second λ threshold that is greater than the first λ threshold and whether the spark timing correction routine 406 is already enabled. If the second condition 446 is "yes," the spark timing correction routine 406 remains enabled. If the second condition 446 is "no," the spark timing correction routine 406 is not enabled and the change in spark timing is set to 0 at an output 448. Thus, the incremental spark timing 408 is also set to zero and the spark timing 414 corresponds to the steady state λ reference 432 (λ ref,ss ).

[0045] The first condition 444 and the second condition 446 determine the presence or absence of a spark timing correction condition. In one embodiment, the first condition 444 and the second condition 446 provide for the enabling and disabling of spark timing correction based on λ thresholds, such as graphically depicted in a graph 450. The spark timing correction mode 452 is only enabled when the feedback λ (λ fdbk ) is less than a first λ threshold and allowed to continue when the feedback λ (λ fdbk ) is below a second λ threshold. Otherwise, as soon as the feedback λ (λ fdbk ) increases above the second λ threshold, the spark timing 414 immediately reverts to the steady state spark timing 436.

[0046] When the spark timing correction routine 406 is enabled, a difference calculation operation 460 determines the difference between the feedback λ fdbk output 442 (λ fdbk ) and the steady state λ reference 432 (λ ref,ss ) and provides a λ difference output 462 (λ diff ). As discussed above, the λ difference output 462 (λ diff ) is provided to a spark timing correction calculation operation 464. The spark timing correction calculation operation 464 determines the spark timing correction relative to the steady state reference spark timing using equation 1 discussed above. Coeffl and Coeff2 can be determined from one-dimensional tables 468, 470 based on the engine speed input 426.

[0047] The spark timing correction routine 406 outputs a spark timing correction, also referred to as an incremental spark timing 408 when enabled. At a summation operation 410, the incremental spark timing 408 is summed with the steady state reference spark timing (ST ref,ss) are added, upper and lower spark timing adjustment limits are applied to the output of the summation operation 410 at a limiter operation 412, and the output 414 of the limiter operation 412 corresponds to a transient spark timing (ST ref,tr ), which is provided to the engine 102 to retard spark timing in response to a transient event.

[0048] Various aspects of the present disclosure are contemplated. For example, according to one aspect, a system for controlling a spark timing in an internal combustion engine is provided. The system includes an electronic controller configured to: determine that a spark timing correction condition exists for the internal combustion engine in response to one or more engine operating parameters; determine a lambda difference between a steady state lambda and a feedback lambda from operation of the internal combustion engine in response to the spark timing correction condition existing, the steady state lambda based on engine speed and engine torque, and the feedback lambda based on at least one of a calculated lambda and a sensed lambda; determine a spark timing correction based on the lambda difference; and control the spark timing to combust fuel in the internal combustion engine based on the spark timing correction.

[0049] In one embodiment, the electronic controller is configured to determine that the spark timing correction condition exists in response to the feedback lambda being less than a first lambda threshold.

[0050] In further embodiments, the electronic controller is configured to determine that the spark timing correction condition remains existing in response to the feedback lambda being less than a second lambda threshold that is greater than the first lambda threshold.

[0051] In one embodiment, the electronic controller is configured to determine the calculated lambda based on an air charge flow to the internal combustion engine and a total fueling amount, and to determine the sensed lambda based on an oxygen sensor output.

[0052] In one embodiment, the spark timing correction is determined by the following equation: where dST is the spark timing correction, lambda fdbk is the feedback lambda, lambda ref,ss is the steady state lambda, and Coeffl is a first coefficient and Coeff2 is a second coefficient, which are from a lookup table and selected based on engine speed.

[0053] In further embodiments, the first coefficient and the second coefficient are calibrated using a transient response test to determine spark timing adjustments that will reduce or mitigate knock at various engine speeds.

[0054] In one embodiment, the electronic controller is configured to limit the spark timing correction based on at least one of an upper limit change limit and a lower limit change limit.

[0055] In one embodiment, the spark timing correction condition is a transient event, and the electronic controller is configured to determine a final fuel amount to provide to the internal combustion engine in response to the transient event based on a fuel reference amount from a fueling table and a transient lambda limit that adjusts the fuel reference amount in response to the feedback lambda.

[0056] In one embodiment, the electronic controller is configured to adjust a steady state spark timing with the spark timing correction to control the spark timing.

[0057] In further embodiments, the steady state spark timing is determined based on engine speed and engine torque from a lookup table.

[0058] In one embodiment, the electronic controller is configured to determine the spark timing correction without sensing knock. In one embodiment, the internal combustion engine combusts hydrogen fuel.

[0059] In one embodiment, the system includes the internal combustion engine. The internal combustion engine includes a plurality of cylinders to receive an intake airflow and a fuel, and a plurality of spark plugs associated with respective ones of the plurality of cylinders. The plurality of spark plugs are controlled by the electronic controller to combust the intake airflow and the fuel at the spark timing.

[0060] According to another aspect of the disclosure, a method for controlling a spark timing in an internal combustion engine is provided. The method includes determining that a spark timing correction condition exists for an internal combustion engine in response to one or more engine operating parameters, determining a lambda difference between a steady state lambda and a feedback lambda during operation of the internal combustion engine in response to the spark timing correction condition existing, the steady state lambda based on engine speed and engine torque and the feedback lambda based on at least one of a calculated lambda and a sensed lambda, determining a spark timing correction based on the lambda difference, and controlling the spark timing based on the spark timing correction to combust a fuel injection amount in the internal combustion engine.

[0061] In one embodiment, determining that the spark timing correction condition exists includes determining that the feedback lambda is less than a first lambda threshold.

[0062] In further embodiments, the method includes determining that the spark timing correction condition remains existing in response to the feedback lambda being less than a second lambda threshold greater than the first lambda threshold after determining that the spark timing correction condition exists. In further embodiments, the first lambda threshold is 1.8 and the second lambda threshold is 2.0.

[0063] In one embodiment, the calculated lambda is determined based on a charge air flow to the internal combustion engine and a total fuel supply amount. The sensed lambda is determined based on an output of an oxygen sensor.

[0064] In one embodiment, the method includes determining a steady state spark timing based on engine torque and engine speed, and applying the spark timing correction to the steady state spark timing to control the spark timing.

[0065] In one embodiment, the method includes limiting the spark timing correction based on at least one of an upper limit variation limit and a lower limit variation limit.

[0066] While this application has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the application is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements. Accordingly, the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, to the extent the following claims are construed to cover all equivalent structures and processes disclosed within this specification and their equivalents, such claims are intended to cover any and all equivalents. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in the introductory clauses of the claims. Moreover, the term "first" and / or "second" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and / or "one" and / or "two" and / or "third" and / or "fourth" and

Claims

1. A system for controlling spark timing in an internal combustion engine, the system comprising: Electronic controller, the electronic controller being configured to: The existence of spark timing correction conditions for the internal combustion engine is determined in response to one or more engine operating parameters; In response to the presence of the spark timing correction condition, a λ difference is determined between a steady-state λ and a feedback λ from the operation of the internal combustion engine, the steady-state λ being based on engine speed and engine torque, and the feedback λ being based on at least one of a calculated λ and a sensed λ. Spark timing correction is determined based on the λ difference; and The spark timing is controlled based on the spark timing correction to burn fuel in the internal combustion engine.

2. The system of claim 1, wherein the electronic controller is configured to determine that the spark timing correction condition exists in response to the feedback λ being less than a first λ threshold.

3. The system of claim 2, wherein the electronic controller is configured to determine that the spark timing correction condition remains present in response to the feedback λ being less than a second λ threshold greater than the first λ threshold.

4. The system of claim 1, wherein the electronic control system is configured to: The calculated λ is determined based on the charging flow and total fuel supply to the internal combustion engine; and The sensed λ is determined based on the oxygen sensor output.

5. The system according to claim 1, wherein the spark timing correction is determined by the following formula: Where dST is the spark timing correction, and λ fdbk It is feedback λ, λ ref,ss It is the steady state λ, and Coeff1 is the first coefficient and Coeff2 is the second coefficient. They are derived from a lookup table and selected based on engine speed.

6. The system of claim 5, wherein a transient response test is used to calibrate the first and second coefficients to determine spark timing adjustments that will reduce or mitigate knocking at various engine speeds.

7. The system of claim 1, wherein the electronic controller is configured to limit the spark timing correction based on at least one of an upper limit variation limit and a lower limit variation limit.

8. The system of claim 1, wherein the spark timing correction condition is a transient event, and the electronic controller is configured to determine the final amount of fuel supplied to the internal combustion engine in response to the transient event based on a fuel reference amount from a fuel supply meter and a transient λ limit for adjusting the fuel reference amount in response to the feedback λ.

9. The system of claim 1, wherein the electronic controller is configured to use the spark timing correction to adjust the steady spark timing to control the spark timing.

10. The system of claim 9, wherein the steady spark timing is determined based on engine speed and engine torque using a lookup table.

11. The system of claim 1, wherein the electronic controller is configured to determine the spark timing correction without sensing knock.

12. The system of claim 1, wherein the internal combustion engine burns hydrogen fuel.

13. The system of claim 1, further comprising the internal combustion engine, the internal combustion engine comprising: Multiple cylinders used to receive intake airflow and fuel; as well as A plurality of spark plugs associated with a corresponding cylinder among the plurality of cylinders, the plurality of spark plugs being controlled by the electronic controller to ignite the intake airflow and the fuel at the spark timing.

14. A method for controlling spark timing in an internal combustion engine, the method comprising: The existence of spark timing correction conditions for the internal combustion engine is determined in response to one or more engine operating parameters; In response to the presence of the spark timing correction condition, a λ difference is determined between a steady-state λ and a feedback λ during the operation of the internal combustion engine, the steady-state λ being based on engine speed and engine torque, and the feedback λ being based on at least one of a calculated λ and a sensed λ. Spark timing correction is determined based on the λ difference; and The spark timing is controlled based on the spark timing correction to burn a certain amount of fuel injection in the internal combustion engine.

15. The method of claim 14, wherein determining that the spark timing correction condition exists includes determining that the feedback λ is less than a first λ threshold.

16. The method of claim 15, further comprising: After determining that the spark timing correction condition exists, the spark timing correction condition is determined to remain in response to the feedback λ being less than a second λ threshold greater than the first λ threshold.

17. The method of claim 16, wherein the first λ threshold is 1.8 and the second λ threshold is 2.

0.

18. The method of claim 14, wherein: The calculated λ is determined based on the charging flow and total fuel supply to the internal combustion engine; and The sensed λ is determined based on the output of the oxygen sensor.

19. The method of claim 14, further comprising: Determine steady-state spark timing based on engine torque and engine speed; and The spark timing correction is applied to the steady-state spark timing to control the spark timing.

20. The method of claim 14, further comprising limiting the spark timing correction based on at least one of an upper limit variation limit and a lower limit variation limit.

Images