System and method for adaptive management of engine knock

Abstract

The invention discloses a system and method for adaptively managing engine knock. In one example, an engine system is disclosed herein that includes an engine including a plurality of engine cylinders; and a controller operable to: control a respective ignition timing for each of the plurality of engine cylinders; detecting an increase in knock intensity of the engine; comparing the knock intensity of the engine with a threshold knock intensity after detecting the increase in the knock intensity of the engine; delaying a respective ignition timing for each of the plurality of engine cylinders by the same amount if the knock intensity of the engine is greater than the threshold knock intensity; and if the knock intensity of the engine is less than the threshold knock intensity, delaying the first ignition timing of the first engine cylinder by a first amount independent of the second ignition timing of the second engine cylinder.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to internal combustion engines, and more particularly to methods and systems for adaptively managing knock within an internal combustion engine. BACKGROUND

[0002] An internal combustion engine (ICE) includes one or more engine cylinders. Each engine cylinder is coupled to an assembly of components, such as intake valves, exhaust valves, fuel injectors, spark plugs, and pistons, that act in concert to perform an engine cycle. An engine cycle can include one or more phases (e.g., strokes) for receiving and / or combusting a fuel (e.g., a gaseous fuel such as natural gas), providing torque to a drivetrain, and expelling exhaust gases. The operation of these components and / or the performance of an engine cycle can be carefully coordinated to enable the ICE to operate safely and efficiently.

[0003] For example, an engine cycle can include four strokes: 1) an intake stroke in which a piston moves toward a bottom of a combustion chamber formed by an engine cylinder and air is allowed to enter the combustion chamber; 2) a compression stroke in which the piston moves toward a top of the combustion chamber and contents of the combustion chamber are compressed; 3) a power stroke in which fuel within the combustion chamber is ignited and the piston is driven back toward the bottom of the combustion chamber by combustion of the fuel; and 4) an exhaust stroke in which the piston again moves toward the top of the combustion chamber and exhaust gases resulting from combustion of the fuel are expelled from the combustion chamber. To most efficiently produce torque, fuel within the combustion chamber is ignited by a spark plug immediately before the piston reaches the top of the combustion chamber, resulting in a flame front that grows in a controlled manner and eventually consumes nearly all of the fuel contained within the combustion chamber. However, if subjected to enough heat and / or pressure, fuel contained within the combustion chamber that is not consumed by the flame front can detonate and / or combust in an uncontrolled manner, a phenomenon known as knock. Knock can cause damage to the engine and / or force the engine to shut down.

[0004] An ignition system for a spark-ignited internal combustion engine is disclosed in US 4,243,007 to Ehrhardt et al. (the '007 patent). The system described in the '007 patent detects knock within the engine and delays the ignition timing of individual engine cylinders in response to the detected knock. The '007 patent does not disclose a method or system that includes comparing a knock intensity of the engine to a threshold knock intensity and adjusting the ignition timing of multiple engine cylinders of the engine collectively or individually based on the comparison of the knock intensity of the engine to the threshold knock intensity.

[0005] The methods and systems of this invention can solve one or more of the problems described above and / or other problems in the art. However, the scope of protection provided by this invention is defined by the appended claims, and not by its ability to solve any particular problem. Summary of the Invention

[0006] In one aspect, an engine system includes an engine comprising a plurality of engine cylinders; and a controller operable to: control the ignition timing of a corresponding engine cylinder in the plurality of engine cylinders; detect an increase in engine knock intensity; after detecting an increase in engine knock intensity, compare the engine knock intensity with a threshold knock intensity; if the engine knock intensity is greater than the threshold knock intensity, delay the corresponding ignition timing of each engine cylinder in the plurality of engine cylinders by the same amount; and if the engine knock intensity is less than the threshold knock intensity, delay the first ignition timing of a first engine cylinder in the plurality of engine cylinders by a first amount, independent of the second ignition timing of a second engine cylinder in the plurality of engine cylinders.

[0007] On the other hand, an engine controller includes a processor and a memory storing instructions for instructing the processor to: detect an increase in engine knock intensity; after detecting an increase in engine knock intensity, compare the engine knock intensity with a threshold knock intensity; if the engine knock intensity is greater than the threshold knock intensity, delay the corresponding ignition timing of each of a plurality of engine cylinders in the engine by a first amount; and if the engine knock intensity is less than the threshold knock intensity, delay the first ignition timing of a first engine cylinder of the plurality of engine cylinders by a second amount less than the first amount.

[0008] On the other hand, a method for controlling an engine includes: detecting an increase in the knock intensity of the engine; and jointly delaying the ignition timing of a corresponding engine cylinder in a plurality of engine cylinders in the engine, wherein the first ignition timing of a first engine cylinder in the plurality of engine cylinders is delayed by a first amount, and the second ignition timing of a second engine cylinder in the plurality of engine cylinders is delayed by a second amount different from the first amount. Attached Figure Description

[0009] Various exemplary embodiments are illustrated in conjunction with the accompanying drawings, which are included in and constitute a part of this specification, and together with the specification serve to explain the principles of the disclosed embodiments.

[0010] Figure 1 A schematic diagram of an exemplary engine including an exemplary plurality of engine cylinders is depicted.

[0011] Figure 2A block diagram of an exemplary engine controller is depicted;

[0012] Figure 3 A diagram depicting exemplary operation of an exemplary plurality of spark plugs included in respective plurality of engine cylinders; and

[0013] Figure 4 A flowchart depicts a method for controlling an engine system. Detailed Implementation

[0014] The foregoing general description and the following detailed description are merely exemplary and illustrative and do not limit the claimed features. As used herein, the terms “comprises,” “comprising,” “having,” “including,” or other variations thereof are intended to cover non-exclusive inclusions, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but may also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Furthermore, in this invention, relative terms such as “about,” “substantially,” “generally,” and “approximately” are used to indicate possible variations of ±10% in the stated values. In this invention, the term “based on,” or any other variation thereof, is intended to cover, for example, “partially based,” “at least partially based,” and “entirely based.”

[0015] Figure 1 A schematic diagram of an exemplary engine system 10 is depicted, which includes an internal combustion engine 14 having a plurality of engine cylinders 20, a fuel source 30, and an electronic control module 80. The engine system 10 can be configured to collectively or individually adapt the corresponding ignition timing of each engine cylinder 20 included in the engine 14 in response to a detected change in the knock intensity of the engine 14.

[0016] Although engine system 10 is Figure 1The engine system 10 is depicted as including six engine cylinders 20, but it will be understood that the engine system 10 may include any number of engine cylinders 20, such as one engine cylinder 20, two engine cylinders 20, four engine cylinders 20, six engine cylinders 20, eight engine cylinders 20, twelve engine cylinders 20, etc. As described above, each engine cylinder 20 included in the engine system 10 may include or otherwise operatively coupled to a plurality of components that work together to burn fuel according to an engine cycle (e.g., a four-stroke engine cycle as described above). Fuel may be received by the engine 14 from a fuel source 30, such as a fuel tank and / or an on-site fuel source such as a natural gas pipeline. Fuel may be received by the engine 14 of the engine system 10 in any suitable manner, such as via intake port injection, fumigation, or direct injection.

[0017] Engine system 10 may include spark plug 22, operable to ignite fuel contained within engine cylinder 20, such as fuel in a combustion chamber formed together with engine cylinder 20. Spark plug 22 may be operable to ignite the fuel contained within engine cylinder 20 at a precisely determined and / or controlled timing relative to the operation of one or more other components of the component assembly (such as a piston disposed within engine cylinder 20) to most efficiently generate torque. The timing of spark plug 22 may be referred to as the ignition timing of engine cylinder 20 and may be measured based on crank angle (e.g., the rotation angle of the crankshaft of engine system 10 measured from the position of the piston of engine system 10 at its highest point) or top dead center (TDC) (e.g., the TDC of the compression stroke). The ignition timing of engine cylinder 20 may be determined or controlled by engine controller 80, such as by generating a command for spark plug 22, such as ignition timing control command 85. Figure 2 For example, for a four-stroke engine cycle including a 720-degree crankshaft, the engine controller 80 can generate an ignition timing control command 85 and transmit it to each spark plug 22 included in the engine 14 to ignite the fuel contained in the engine cylinder 20 at an ignition timing shortly before the power stroke, for example, between 5 and 40 degrees before the 360-degree crankshaft angle.

[0018] As described above, engine system 10 may additionally or optionally include fuel injectors (not shown) operable to inject fuel from fuel source 30 into engine 14, such as into engine cylinders 20. For example, each engine cylinder 20 may be operably coupled to a separate and corresponding fuel injector included in engine 14. The fuel injector may be operable to inject fuel into engine 14 at a precisely determined and / or controlled timing relative to the operation of one or more other components of the component (such as pistons disposed within engine cylinders 20) to most efficiently generate torque. The timing of the fuel injector may be referred to as the injection timing of the fuel injector or the injection timing of the engine cylinder 20 operably coupled to the fuel injector, or injection start (SOI) timing, and may be measured based on crank angle. The injection timing of the fuel injector may be determined or controlled by engine controller 80, such as by generating commands for the fuel injector. For example, for a four-stroke engine cycle including a 720-degree crankshaft, the engine controller 80 can generate a command and transmit the command to each fuel injector included in the engine 14 to inject fuel into the engine 14 at the injection timing at the start of the intake stroke (e.g., 360 degrees before the TDC).

[0019] Engine system 10 may further include one or more sensors operable to sense, measure, detect, and / or meter one or more characteristics of engine cylinder 20 or other components of engine 14. For example, engine 14 may include knock sensor 24 operable to detect or measure the knock intensity of engine 14, as described in further detail below. For example, knock sensor 24 may be a piezoelectric sensor operable to detect knock in the form of vibration within engine cylinder 20. Alternatively, knock sensor 24 may be a pressure sensor, such as an intra-cylinder pressure sensor (ICPS), operable to measure pressure within engine cylinder 20.

[0020] Figure 2 A block diagram of an exemplary engine controller 80 (e.g., an electronic control module (ECM)) is depicted. Engine controller 80 may include memory 81, processor 82, or any other means for performing tasks consistent with the present invention. Memory 81 may store data and / or software operable to enable processor 82 to perform various functions. Specifically, memory 81 and / or processor 82 may allow engine controller 80 to perform any of the adaptive ignition timing functions described herein. Many commercially available microprocessors can be configured to perform the functions of engine controller 80. Various other known circuits may be associated with engine controller 80, including signal conditioning circuitry, communication circuitry, and / or other suitable circuitry.

[0021] The engine controller 80 may include one or more modules operable to receive sensed inputs and generate commands and / or other signals to control the operation of the engine 10. For example, the engine controller 80 may include a knock management module 83 (e.g., instructions stored in memory 81) operable to receive sensor data 25 from one or more sensors (e.g., knock sensors 24) included in the engine cylinder 20 of the engine 10, and generate an ignition timing control command 85 based on the sensor data 25. The ignition timing control command 85 may be transmitted to the spark plug 22 of the engine cylinder 20 to control the spark plug 22 to ignite the fuel contained in the engine cylinder 20 at a specific ignition timing, as described above, for example, to reduce and / or optimize the knock intensity of the engine 10, as further described in detail below. The engine controller 80 may also include a calibration module 84 (e.g., instructions stored in memory 81), operable to receive sensor data 25 from one or more sensors of the engine system 10 (e.g., knock sensor 24) and generate a calibration factor for the engine cylinder 20 based on the sensor data 25. When an ignition timing control command 85 for the engine cylinder 20 is generated, the knock management module 83 can use the calibration factor for the engine cylinder 20 generated by the calibration module 84.

[0022] Industrial applicability

[0023] The systems, apparatus, and methods disclosed herein can be applied to any machine employing an engine 14 (e.g., an internal combustion engine (ICE)). Specifically, the systems, apparatus, and methods disclosed herein can be used in any machine where the ignition timing or injection timing of the engine cylinder 20 of an engine 14 that can receive different types or qualities of fuel needs to be adjusted.

[0024] As described above, if the fuel consumed by the flame front of the spark plug 22, which is contained within engine cylinder 20 but not ignited by the spark plug 22, is subjected to sufficient heat and / or pressure, detonation may tend to occur. Different types or qualities of fuel can exhibit different ignition resistances. For example, for gaseous fuels such as natural gas, the fuel-to-ignition resistance can be measured according to the methane number (MN). Or, for example, for liquid fuels such as unleaded gasoline or diesel, the fuel-to-ignition resistance can be measured according to the octane number or cetane number. On the methane number scale, the higher the value for a particular fuel, the better its ignition resistance. On the cetane number scale, the higher the value for a particular fuel, the lower its ignition resistance.

[0025] The earlier the ignition timing of engine cylinder 20, the greater the likelihood of knocking within engine cylinder 20, for example, because the fuel contained in engine cylinder 20 can be given more time and / or opportunity to detonate after the spark plug 22 has been ignited. Therefore, engine cylinder 20 of an engine 14 designed to operate with fuels with a higher likelihood of knocking can have a relatively delayed ignition timing than engine cylinder 20 of an engine 14 designed to operate with fuels with a lower likelihood of knocking, for example, to reduce the time and / or opportunity for the fuel contained in engine cylinder 20 to detonate.

[0026] While delayed ignition timing may help prevent detonation, the more the ignition timing of the engine cylinders 20 of engine 14 is delayed, the worse the fuel efficiency of engine 14 becomes and / or the exhaust temperature of engine 14 tends to become higher, which may increase the cost of operating engine 14 and / or affect the performance of aftertreatment systems operably coupled to engine 14.

[0027] As described above, engine 14 can receive different types or masses of fuel, which may have different levels of ignition resistance. If the ignition timing of the engine cylinders 20 included in engine 14 has been set to an optimal specific crank angle for a fuel with a specific ignition resistance, and engine 14 later receives fuel with a different ignition resistance, engine 14 or its performance may be negatively affected. As described further below, when engine 14 included in engine system 10 receives different types or masses of fuel, engine controller 80 may be operable to dynamically adjust or adapt the corresponding ignition timings of the multiple spark plugs 22 included in engine system 10, either jointly or individually, such as by employing knock management module 83 and / or calibration module 84, to improve the efficiency, reliability, and / or safety of engine 14.

[0028] Figure 3 A diagram illustrating exemplary operation of a plurality of exemplary spark plugs 22 included in respective plurality of engine cylinders 20 of engine 14 is depicted. In this example, engine 14 includes six engine cylinders 20 and operates according to a four-stroke engine cycle as described above. Figure 3 In the graph, for each of the six engine cylinders 20, the corresponding ignition timings 26A-26F are plotted over time (e.g., as measured according to the engine cycle). Ignition timings 26A-26F are measured based on the crank angle angle prior to TDC. For example, at time t7, the ignition timing 26F of the first engine cylinder 20 is delayed more than the ignition timing 26A of the second engine cylinder 20.

[0029] exist Figure 3 The chart also depicts the percentage of relatively low MN fuel B mixed into the relatively high MN fuel A supplied to engine 14. Figure 3 The corresponding knock intensity for each of the six engine cylinders 20 is also shown, both plotted over time (e.g., on each cycle of the four-stroke engine cycle of engine 14). For example, between time zero (e.g., where the X-axis intersects the Y-axis) and time t1, the percentage 31 of fuel B mixed into fuel A is P1%, and the corresponding knock intensity of the six engine cylinders 20 fluctuates slightly around an average knock intensity level approximately k1. After time t1, the percentage 31 of fuel B mixed into fuel A increases sharply to approximately P5%, thereby drastically reducing the detonation resistance of the fuel mixture. Shortly thereafter, as a result, around time t2, the corresponding knock intensity of the six engine cylinders 20 fluctuates more violently, with some approaching intensity level k2.

[0030] In this example, each of the six engine cylinders 20 includes a corresponding knock sensor 24, operable to detect and / or measure the knock intensity of the engine cylinder 20 over time. Through a communication link between the knock sensor 24 and the engine controller 80, the knock intensity of the six engine cylinders 20 is provided to the engine controller 80 as sensor data 25. The engine controller 80 can then use the sensor data 25 to generate ignition timing control commands 85 for the six engine cylinders 20. In this way, the corresponding ignition timing of the six engine cylinders 20 can be adjusted or adapted to changes in the conditions of the engine 14, such as changes in the type or quality of fuel supplied to the engine 14.

[0031] For example, such as Figure 3 As depicted, when the knock intensity of engine 14 (e.g., the individual, combined, or average knock intensity of the respective engines 14 cylinders 20) increases near time t2 due to an increase in the percentage of fuel B mixed with fuel A, engine controller 80 is able to detect the increase in knock intensity of engine 14 via sensor data 25 generated by knock sensors 24 included in the six engines 20. In response to detecting the increase in knock intensity of engine 14, engine controller 80 generates ignition timing control commands 85 to delay the corresponding ignition timings 26A-26F of the six engines 20. Figure 3 As described, by delaying the ignition timing of the six engine cylinders 20, the engine controller 80 is able to reduce the knock intensity of the engine 14.

[0032] In response to the detection of multiple engine cylinders 20 (e.g., Figure 3In the example described herein, if the knock intensity of engine 14 (six engine cylinders 20) increases, engine controller 80 may, for example, employ knock management module 83 to jointly and / or individually delay the corresponding ignition timing of multiple engine cylinders 20. For example, after detecting an increase in the knock intensity of engine 14, engine controller 80 may compare the knock intensity of engine 14 with a threshold knock intensity 32. If the knock intensity of engine 14 is greater than the threshold knock intensity 32, engine controller 80 may jointly (e.g., globally) delay the corresponding ignition timing of multiple engine cylinders 20. As described further in detail below, engine controller 80 may jointly delay the corresponding ignition timing of multiple engine cylinders 20 by simultaneously delaying the corresponding ignition timing of multiple engine cylinders 20 by the same amount and / or the same degree.

[0033] Alternatively, if the knock intensity of engine 14 is less than the threshold knock intensity 32, engine controller 80 can individually delay the respective ignition timings of multiple engine cylinders 20. As described in further detail below, engine controller 80 can individually delay the respective ignition timings of multiple engine cylinders 20 by delaying them at different times, by different amounts, and / or by different degrees. When engine controller 80 individually delays the respective ignition timings of multiple engine cylinders 20, engine controller 80 can delay the ignition timing of an individual engine cylinder 20 independently of the ignition timing of any other engine cylinder 20.

[0034] Engine controller 80 (e.g., via knock management module 83) can compare the knock intensity of engine 14 with threshold knock intensity 32 in various ways. For example, when comparing the knock intensity of engine 14 with threshold knock intensity 32, engine controller 80 can determine the value of knock intensity and compare the value of knock intensity with threshold knock intensity 32. Or, for example, when comparing the knock intensity of engine 14 with threshold knock intensity 32, engine controller 80 can determine the rate of change of knock intensity and compare the rate of change of knock intensity with threshold knock intensity. Or, for example, when comparing the knock intensity of engine 14 with threshold knock intensity 32, engine controller 80 can determine the value of knock intensity and compare the value of knock intensity with a rolling or moving average of the knock intensity of engine 14. However, engine controller 80 can compare the knock intensity of engine 14 or an increase in the knock intensity of engine 14 with threshold knock intensity 32 in any other suitable manner.

[0035] exist Figure 3In the depicted example, engine controller 80 determines that the increase in knock intensity of engine 14 is greater than a threshold knock intensity 32 near time t2. In response, engine controller 80 collectively delays the corresponding ignition timings 26A-26F of the six engine cylinders 20. Figure 3 As depicted, when the respective ignition timings 26A-26F of multiple engine cylinders 20 are jointly delayed, the engine controller 80 can simultaneously delay the respective ignition timings of the multiple engine cylinders 20, although the amount or degree to which the respective ignition timings of the individual engine cylinders 20 are delayed can be based on factors specific to the individual engine cylinder 20, such as calibration factors determined for the individual engine cylinder 20, as described in further detail below. However, the engine controller 80 can jointly delay the respective ignition timings of the multiple engine cylinders 20 in various ways. For example, when jointly delaying the respective ignition timings of the multiple engine cylinders 20, the engine controller 80 can simultaneously and / or delay the respective ignition timings of the multiple engine cylinders 20 by the same amount (e.g., the same amount of crank angle) or to the same degree (e.g., the same crank angle).

[0036] exist Figure 3 In the depicted example, after reaching approximately P5% around time t1, the percentage 31 of fuel B mixed in fuel A stabilizes at P4% between times t2 and t3, gradually decreases, then stabilizes again at approximately P2% between times t4 and t5, then increases sharply, and stabilizes again at P3% between times t5 and t8. In this example, when the percentage 31 of fuel B mixed in fuel A increases to P3%, the knock intensity of engine 14 increases, but does not exceed the threshold knock intensity 32. In response to detecting an increase in the knock intensity of engine 14 and determining that the increase in the knock intensity of engine 14 is less than the threshold knock intensity 32, engine controller 80 individually delays the corresponding ignition timings 26A-26F of the six engine cylinders 20. Figure 3 As described, when individually delaying the respective ignition timings of multiple engine cylinders 20, the engine controller 80 can delay the ignition timing of an individual engine cylinder 20 among the multiple engine cylinders 20 independently of any other ignition timing of any other engine cylinder 20. When individually delaying the respective ignition timings of multiple engine cylinders 20, the engine controller 80 can delay the respective ignition timings of the multiple engine cylinders 20 at different times and / or by different amounts or to different degrees.

[0037] When individually delaying the ignition timing of a plurality of engine cylinders 20, the engine controller 80 may delay the ignition timing of an individual engine cylinder 20 based on sensor data 25 generated for each individual engine cylinder 20. For example, if simultaneously, if a first knock sensor 24 for a first engine cylinder 20 detects a first increase in knock intensity within the first engine cylinder 20, and a second knock sensor 24 for a second engine cylinder 20 detects a second increase in knock intensity within the second engine cylinder 20, the second increase being less than the first increase in knock intensity within the first engine cylinder 20, then the engine controller 80 may delay the first ignition timing of the first engine cylinder 20 by a first amount or a first degree, and delay the second ignition timing of the second engine cylinder 20 by a second amount or a second degree, the second amount being less than the first amount and the second degree being earlier than the first degree. Alternatively, for example, when individually delaying the ignition timing of a plurality of engine cylinders 20, the amount by which the engine controller 80 delays the ignition timing of an individual engine cylinder 20 may be based on the value of the knock intensity within the individual engine cylinder 20. For example, when delaying the ignition timing of corresponding components of multiple engine cylinders 20, the engine controller 80 can determine a first value of the knock intensity detected in the first engine cylinder 20 and a second value of the knock intensity detected in the second engine cylinder 20 that is less than the first value. In this example, because the first value is greater than the second value, the engine controller 80 can delay the first ignition timing of the first engine cylinder 20 by a greater amount than delay the second ignition timing of the second engine cylinder 20.

[0038] A desired balance can exist between delaying the ignition timing of the engine cylinders 20 of engine 14 to reduce knock and advancing the ignition timing of the engine cylinders 20 to improve fuel efficiency and / or reduce the exhaust temperature of engine 14. To this end, engine controller 80 may be operable to find a target knock intensity level 33 for engine 14, for example, for each of the plurality of engine cylinders 20 included in engine 14. To this end, engine controller 80 may compare the target knock intensity level 33 with the average knock intensity of the plurality of engine cylinders 20 and / or with individual values ​​of the knock intensity of individual engine cylinders 20. If the target knock intensity level 33 is exceeded, engine controller 80 may delay the corresponding ignition timing of one or more of the plurality of engine cylinders 20, and if the target knock intensity level 33 is not exceeded, engine controller 80 may advance the corresponding ignition timing of one or more of the plurality of engine cylinders 20.

[0039] For example, such as Figure 3As depicted, the target knock intensity level 33 of engine 14 has been set to the knock intensity level of k1. Between time t3 and time t6, the average knock intensity of the six engine cylinders 20 does not exceed the target knock intensity level 33. Because the average knock intensity of the six engine cylinders 20 does not exceed the target knock intensity level 33, the engine controller 80 gradually advances the corresponding ignition timing of the six engine cylinders 20. In some embodiments, when advancing the ignition timing of the engine cylinders 20, the engine cylinders 20 can advance their ignition timing by an increment and / or a predetermined amount during each consecutive cycle of the four-stroke engine cycle. In some embodiments, the amount by which the engine controller 80 advances the ignition timing of individual engine cylinders 20 can be based on factors specific to individual engine cylinders 20, such as calibration factors determined for individual engine cylinders 20, as described in further detail below.

[0040] After time t6, in response to the increase and stabilization of the percentage 31 of fuel B mixed with fuel A at approximately P3%, the average knock intensity of the six engine cylinders 20 begins to exceed the target knock intensity level 33. In response, when / if the knock intensity within the corresponding engine cylinder 20 exceeds the target knock intensity level 33, the engine controller 80 individually delays the corresponding ignition timings 26A-26F of the six engine cylinders 20. Then, after delaying the ignition timings of the engine cylinders 20, as described above, the engine controller 80 gradually advances the ignition timings of the engine cylinders 20 until the knock intensity within the engine cylinders 20 again exceeds the target knock intensity level 33, or until the upper limit of the ignition timing is reached. Figure 3 As described, if the upper limit of ignition timing is not reached, the delay and advance of the ignition timing of the engine cylinder 20 by the engine controller 80 can produce the characteristic chopping of the ignition timing of the engine cylinder 20.

[0041] For various reasons, the effect of adjusting the ignition timing of one engine cylinder 20 may differ from the effect of the same adjustment to the ignition timing of another engine cylinder 20. For example, differences in geometry, wear level, position, etc., between the first and second engine cylinders 20 may cause a delay in the ignition timing of the first engine cylinder 20 to reduce knock more effectively than the same delay in the ignition timing of the second engine cylinder 20, or cause an advance in the ignition timing of the second engine cylinder 20 to produce more knock than the same advance in the ignition timing of the first engine cylinder 20. Therefore, as described above, the amount by which the engine controller 80 delays or advances the ignition timing of an individual engine cylinder 20 can be based on factors specific to that individual engine cylinder 20.

[0042] For example, engine controller 80 (e.g., via calibration module 84) can identify, determine, or generate calibration factors for individual engine cylinders 20. In some embodiments, calibration factors can be determined for individual engine cylinders 20 during one or more end-of-line (EOL) tests performed on engine 14 prior to its field use. In some embodiments, calibration factors can be determined for individual engine cylinders 20 during field use of engine 14. For example, engine controller 80 can be operable to analyze sensor data 25 generated over time by knock sensor 24 included in engine cylinder 20 to determine the effect of ignition timing delay of engine cylinder 20 in reducing knock, and accordingly generate calibration factors for engine cylinder 20. Additionally or alternatively, engine controller 80 can be operable to analyze sensor data 25 generated over time by knock sensor 24 included in engine cylinder 20 to determine the likelihood or extent of knock within engine cylinder 20 caused by advance ignition timing of engine cylinder 20, and accordingly generate calibration factors for engine cylinder 20. In some embodiments, engine cylinder 20 may receive an initial calibration factor determined during one or more EOL tests performed prior to field use of engine cylinder 20, and the calibration factor of engine cylinder 20 may be periodically updated, for example, based on sensor data 25 generated by knock sensor 24 included in engine cylinder 20 throughout field use of engine cylinder 20.

[0043] The calibration factor determined or generated for engine cylinder 20 can be a scaling factor and / or a scaling factor relative to a standard or default calibration value. For example, in some embodiments, the default calibration value for any engine cylinder 20 can be 0%, and a positive or negative calibration factor can be assigned to individual engine cylinder 20 relative to the 0% default calibration value, such as +5% or -5%. For example, in response to detecting an increase in the knock intensity of engine 14 exceeding the knock intensity threshold 32, as described above, engine controller 80 can determine that the corresponding ignition timing of all engine cylinders 20 included in engine 14 will be delayed by one crank angle. In this example, engine controller 80 then identifies a specific engine cylinder 20 included in engine 14 that has already been given a +5% calibration factor, and instead of delaying the ignition timing of the specific engine cylinder 20 by one crank angle, engine controller 80 delays the ignition timing of the specific engine cylinder 20 by 1.05 crank angles according to the +5% calibration factor given to the specific engine cylinder 20.

[0044] In some embodiments, based at least in part on an increase in the knock intensity of engine 10 detected by engine controller 80, engine controller 80 may be operable to determine and / or output a value indicating the ignition resistance (e.g., methane number or octane number) of the fuel supplied to engine 14. For example, engine controller 80 may include data relating a specific methane number to an expected knock intensity at a specific ignition timing. In this example, using this data, if engine controller 80 detects that the knock intensity of engine 14 is greater than the expected knock intensity at a specific ignition timing, engine controller 80 is able to determine the methane number of the fuel supplied to engine 14, e.g., relative to a specific methane number. Engine controller 80 may then output the determined methane number of the fuel supplied to engine 14 to a control interface (e.g., a display) of a vehicle, such as in which engine system 10 is incorporated.

[0045] Figure 4 A flowchart of a method 100 for controlling an engine system 10 is depicted. The engine system 10 may include an engine 14 and an engine controller 80. The engine 14 includes a plurality of engine cylinders 20. The method 100 may be repeatedly performed during operation of the engine system 10 to adjust commands (e.g., ignition timing control command 85) generated and / or output by the engine controller 80 in response to changing engine conditions (e.g., different types or qualities of fuel supplied to the engine 14). Although the steps of the method 100 are shown and discussed in a specific order, it should be understood that any step of the method 100 may be performed in any suitable order, or simultaneously.

[0046] like Figure 4 As depicted, method 100 may begin at step 102, in which engine controller 80 detects an increase in the knock intensity of engine 14 of engine system 10. For example, as described above, engine 14 may include a plurality of engine cylinders 20, and each of the plurality of engine cylinders 20 may include a knock sensor 24 operable to detect knock within engine cylinder 20. Sensor data 25 generated by knock sensor 24 may be provided to engine controller 80, and engine controller 80 may be operable to use sensor data 25 to detect an increase in the knock intensity of the engine. As described above, knock sensor 24 may be a piezoelectric sensor or a pressure sensor (e.g., an in-cylinder pressure sensor or ICPS).

[0047] like Figure 4As described, after detecting an increase in the knock intensity of engine 14, method 100 may proceed to step 104, where engine controller 80 compares the knock intensity of engine 14 with a threshold knock intensity 32. In some embodiments, the threshold knock intensity 32 is a standard value, a default value, or a predetermined value. In some embodiments, the threshold knock intensity 32 is updated throughout the operation of engine 14 and may be based at least in part on a rolling or moving average of knock intensities detected within engine 14 (e.g., within one or more engine cylinders 20 included in engine 14). As discussed above, if the knock intensity of engine 14 is greater than the threshold knock intensity 32, engine controller 80 may collectively delay the corresponding ignition timing of each of the plurality of engine cylinders 20 included in the plurality of engine cylinders 20. Alternatively, if the knock intensity of engine 14 is less than the threshold knock intensity 32, engine controller 80 may delay the corresponding ignition timing of the plurality of engine cylinders 20 on a cylinder-to-cylinder basis.

[0048] As described above, for example, if the knock intensity of engine 14 is greater than the threshold knock intensity 32, engine controller 80 may simultaneously and jointly delay the corresponding ignition timings of multiple engine cylinders 20. When jointly delaying the corresponding ignition timings of multiple engine cylinders 20, the amount or extent to which the ignition timing of an individual engine cylinder 20 is delayed may be based on a calibration factor determined for an individual engine cylinder 20, or the amount or extent to which the ignition timing of each engine cylinder 20 is delayed may be predetermined and / or the same.

[0049] If the knock intensity of engine 14 is less than the threshold knock intensity 32, engine controller 80 can individually delay the ignition timing of a plurality of engine cylinders 20. When individually delaying the ignition timing of a plurality of engine cylinders 20, engine controller 80 can delay the ignition timing of a particular engine cylinder 20 if the knock intensity within that particular engine cylinder 20 exceeds the target knock intensity 33. When individually delaying the ignition timing of a plurality of engine cylinders 20, engine controller 80 can delay the ignition timing of a particular engine cylinder 20 independently of the ignition timing of any other engine cylinder 20. For example, engine controller 80 can delay the ignition timing of a particular engine cylinder 20 by a different time, a different amount, or a different degree than the ignition timing of any other engine cylinder 20. When the ignition timing of a plurality of engine cylinders 20 is delayed individually, the amount or extent to which the ignition timing of an individual engine cylinder 20 is delayed can be based on a calibration factor determined for an individual engine cylinder 20 as described above, or the amount or extent to which the ignition timing of an individual engine cylinder 20 is delayed can be predetermined.

[0050] like Figure 4 As described, after comparing the engine knock intensity with the threshold knock intensity 32, method 100 can proceed to steps 106 and 108, in which the engine controller 80 delays the first ignition timing of the first engine cylinder 20 of the plurality of engine cylinders 20 by a first amount; and in step 108, the engine controller 80 delays the second ignition timing of the second engine cylinder 20 of the plurality of engine cylinders 20 by a second amount less than the first amount.

[0051] For example, as described above, if the knock intensity of engine 14 is greater than the knock intensity threshold 32, the first ignition timing and the second ignition timing can be jointly delayed during the same cycle of a four-stroke engine cycle, even though the first and second amounts are different. As described above, the first amount can be based on a first calibration factor identified or generated for the first engine cylinder 20, and the second amount can be based on a second calibration factor identified or generated for the second engine cylinder 20. Alternatively, for example, if the knock intensity of engine 14 is greater than the knock intensity threshold 32, the engine controller 80 can jointly delay the first and second ignition timing to the same crank angle, even though the first and second amounts are different because the first ignition timing was previously advanced compared to the second ignition timing.

[0052] Alternatively, for example, if the knock intensity of engine 14 is less than the knock intensity threshold 32, the engine controller 80 may, as described above, individually delay the first ignition timing and the second ignition timing by different amounts, and delay by different crank angles or at different times. As described above, the first amount may be based on a first calibration factor identified or generated for the first engine cylinder 20, and the second amount may be based on a second calibration factor identified or generated for the second engine cylinder 20.

[0053] like Figure 4 As depicted, method 100 may proceed to step 110, in which the engine controller 80 advances the first or second ignition timing until a target knock intensity 33 is reached, or until an upper limit of the first or second ignition timing is reached. As described above, during each consecutive cycle of a four-stroke engine cycle, the engine controller 80 may advance the first or second ignition timing by an increment and / or a predetermined amount. The amount by which the engine controller 80 advances the first or second ignition timing may be based on a first calibration factor identified or generated for the first engine cylinder 20 or a second calibration factor identified or generated for the second engine cylinder 20, respectively.

[0054] In the process of jointly and individually adjusting the ignition timing of multiple engine cylinders 20 included in engine 14, engine controller 80 can rapidly and partically adjust the operation of engine 14 in response to different types and qualities of fuel, thereby reducing wear caused by knock and preventing engine shutdown caused by knock. By setting a target knock intensity level 33 and advancing the corresponding ignition timing of the multiple engine cylinders 20 included in engine 14, engine controller 80 can improve the fuel efficiency of engine 14 and prevent the exhaust temperature of engine 14 from becoming undesirably high. By using sensor data 25 generated by pressure sensors disposed in each of the multiple engine cylinders 20 including engine 14, engine controller 80 can reliably detect and measure knock within each engine cylinder 20.

[0055] While the systems and methods disclosed herein are generally described as reducing and / or managing knock within an engine 14 by jointly and / or individually adjusting the ignition timing of a plurality of engine cylinders 20 included in an engine 14, it will be understood and appreciated that the systems and methods disclosed herein may alternatively or additionally reduce and / or manage knock within an engine 14 by jointly and / or individually adjusting the injection timing of a plurality of engine cylinders 20 included in an engine 14. As described above, for example, in response to detecting an increase in the knock intensity of an engine 14 including a plurality of engine cylinders 20, an engine controller 80 may compare the knock intensity of the engine 14 with a threshold knock intensity 32. As described above, if the knock intensity of the engine 14 is greater than the threshold knock intensity 32, the engine controller 80 may jointly delay the corresponding injection timing of each of the plurality of engine cylinders 20, similar to how the engine controller 80 may jointly delay the corresponding ignition timing of each of the plurality of engine cylinders 20. As described above, or, for example, if the knock intensity of engine 14 is less than a threshold knock intensity 32, engine controller 80 may delay the corresponding injection timing of multiple engine cylinders 20 on a cylinder-to-cylinder basis, similar to how engine controller 80 may delay the corresponding ignition timing of each engine cylinder 20 included in the multiple engine cylinders 20 on a cylinder-to-cylinder basis. Similar to how engine controller 80 may delay the corresponding ignition timing of engine cylinders 20 jointly or individually, as described above, regardless of whether engine controller 80 delays the corresponding injection timing of engine cylinders 20 jointly or individually, engine controller 80 may delay the first injection timing of a first engine cylinder 20 in the multiple engine cylinders 20 by a first amount, and delay the second injection timing of a second engine cylinder 20 in the multiple engine cylinders 20 by a second amount different from the first amount. After jointly or individually delaying the respective injection timing of the engine cylinders 20, the engine controller 80 may advance the respective injection timing of one or more of the plurality of engine cylinders 20 until a target knock intensity 33 is reached, or until the upper limit of the respective injection timing of one or more engine cylinders 20 is reached. In reducing and / or managing knock within the engine 14, the engine controller 80 may jointly and / or individually adjust one or both of the respective ignition timing and the respective injection timing of the plurality of engine cylinders 20 included in the engine 14, enabling the engine controller 80 to reduce and / or manage knock within the engine 14 fueled by different types of fuels, such as dual-fuel engines or engines fueled by mixed fuel mixtures.

[0056] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed methods and systems without departing from the scope of the invention. Other embodiments of the methods and systems will be apparent to those skilled in the art upon consideration of the description and practice of the devices and systems disclosed herein. The description and examples are intended to be considered exemplary only, and the true scope of the invention is indicated by the following claims and their equivalents.

Claims

1. An engine system comprising: an engine including a plurality of engine cylinders; and a controller operable to: control a respective firing timing of each of the plurality of engine cylinders; detect an increase in knock intensity of the engine; compare the knock intensity of the engine to a threshold knock intensity after detecting the increase in the knock intensity of the engine; delay the respective firing timing of each of the plurality of engine cylinders by a same amount if the knock intensity of the engine is greater than the threshold knock intensity; and delay a first firing timing of a first engine cylinder of the plurality of engine cylinders by a first amount independent of a second firing timing of a second engine cylinder of the plurality of engine cylinders if the knock intensity of the engine is less than the threshold knock intensity.

2. The engine system of claim 1, wherein the controller is further operable to: determine a calibration factor for the first engine cylinder; and delay the first firing timing of the first engine cylinder by the first amount based at least in part on the calibration factor if the knock intensity of the engine is less than the threshold knock intensity.

3. The engine system of claim 2, wherein the controller is further operable to delay the respective firing timing of each of the plurality of engine cylinders by a predetermined amount if the knock intensity of the engine is greater than the threshold knock intensity.

4. The engine system of any of the preceding claims, wherein the increase in the knock intensity of the engine is detected by a pressure sensor.

5. The engine system of claim 4, wherein the pressure sensor is disposed within the first engine cylinder.

6. The engine system of claim 1, wherein the controller is further operable to: determine a value of the knock intensity of the engine; and delay the first firing timing of the first engine cylinder by the first amount based at least in part on the value of the knock intensity of the engine if the knock intensity of the engine is less than the threshold knock intensity.

7. The engine system of claim 1, wherein the controller is further operable to delay a second firing timing of a second engine cylinder of the plurality of engine cylinders by a second amount different from the first amount if the knock intensity of the engine is less than the threshold knock intensity.

8. The engine system of claim 7, wherein: detecting the increase in the knock intensity of the engine further includes detecting a first increase in the knock intensity within the first engine cylinder and a second increase in the knock intensity within the second engine cylinder; and the controller is further operable to delay the first firing timing by the first amount and the second firing timing by the second amount based at least in part on the first increase in the knock intensity and the second increase in the knock intensity, respectively. ​ 9. The engine system of claim 8, wherein the first increase in knock intensity is detected by a first pressure sensor disposed within the first engine cylinder and the second increase in knock intensity is detected by a second pressure sensor disposed within the second engine cylinder.

10. The engine system of claim 1, wherein the controller is further operable to, if the knock intensity of the engine is less than the threshold knock intensity, advance the first firing timing of the first engine cylinder after delaying the first firing timing of the first engine cylinder by the first amount until a target knock intensity of the engine is reached.

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