System and method for controlling the power of an engine

Abstract

Methods for controlling the power of an engine, comprising: a) Detecting a first signal representing an ion current from an ion sensor that detects a combustion process in a cylinder of the engine; b) Calculating a knock score based on the first signal; c) Determining an operating state of the engine during the combustion process, preferably on the basis of a sensor detecting the operating state and / or a map describing the operating state, preferably on the basis of an engine map including an engine speed and an engine load during the combustion process; d) Determining an expected knocking intensity, which describes an acceptable intensity of a knocking process during the combustion process; e) Selecting one or more multipliers based on the operating state, where a multiplier is preferably at least one of: a. calculated from data provided by the sensor detecting the operating state, preferably the ion sensor and / or a fuel quality sensor and / or a temperature sensor and / or a contamination sensor, and b. selected from a table encompassing the characteristic map, preferably an engine characteristic map, preferably a characteristic map of speed and load; f) Calculate: a. a knock assist value based on the knock index and one or more multipliers, wherein preferably the knock index is multiplied by at least one of the multipliers, and / or b. a knock intensity aid value based on the expected knock intensity and one or more multipliers, wherein preferably at least one expected knock intensity is divided by at least one of the multipliers; g) Repeating steps a) to f) for at least two combustion processes, preferably at least 4 combustion processes, preferably at least 10 combustion processes, preferably at least 50 combustion processes; h) Comparing: a. the calculated tapping aid value with the expected tapping intensity, and / or b. the knock score with the knock intensity aid value, to determine a deviation, where the comparison includes comparing an average value of the knock index and / or the knock assist value and / or the knock intensity assist value over the repeated combustion cycles; and i) Generating an instruction to correct the operation of the engine, preferably to adjust ignition timing and / or fuel injection when the deviation exceeds a threshold indicating that a correction is required.

Description

[0001] This application claims priority from Swedish patent application No. 1350561-5, filed on 7 May 2013. Technical area

[0002] The present invention relates to a method for controlling the performance of an engine, comprising the steps of: detecting an ion current in the form of a first signal, analyzing this first signal to determine at least one characteristic, determining a knock index based on this first signal and preferably on this at least one characteristic, and combining this knock index with at least one multiplier to obtain an engine index. The invention further relates to a system for controlling the performance of an engine. State of the art

[0003] In the field of engine control systems, it is desirable to avoid a phenomenon known as knocking in order to optimize engine performance and prevent engine damage. In order to control engine operation and avoid knocking while optimizing operation, maps (i.e., data tables) are commonly used. A map may be a table of values ​​of a particular parameter at different engine operating conditions (e.g., a particular speed or load). These parameters are typically predetermined for a specific engine. It is also known to use data regarding ion current to detect knocking or to calculate a knock index. The generation of knock in an engine represents a considerable problem, as severe engine damage can also occur when an engine knocks.In an internal combustion engine, the fuel / air mixture is introduced into a combustion chamber and then compressed by the upward motion of a piston. The compressed mixture is ignited and combusted by a spark generated by applying a high voltage to a spark plug installed in the combustion chamber, and the force generated when the piston is pushed downward is recovered as work. Occasionally, the pressure created by the combustion itself can cause the unburned fuel / air mixture to ignite prematurely, producing a smaller, instantaneous combustion of the end gas, which is the cause of knocking. This condition is undesirable because it can damage or destroy engine components, so it is desirable to prevent knocking from occurring.During combustion in the combustion chamber, molecules of the mixture are ionized, so that when a measuring voltage is applied to the spark plug in the combustion chamber, a current—the ionic current—flows due to the electrical charge of the ions. It is known that the ionic current varies depending on the combustion pressure, and therefore the occurrence of knocking (pressure oscillation) can be determined by detecting the signal content of the ionic current.

[0004] The performance of an engine can be affected by a variety of environmental factors - fuel quality, humidity, air quality, oil quality, air temperature, and the like. An engine should be adaptable to different fuel sources (e.g., different ethanol or methanol concentrations in gasoline, different biodiesel concentrations in diesel, and / or different natural gas components). In addition, many engines are designed for multi-fuel use (e.g., use of diesel and natural gas). Within these categories, fuel quality can vary (e.g., the concentration of sulfur, water, and / or other contaminants). Different fuels can have different energy contents. Therefore, different fuels can result in significantly different cylinder pressures for the same amount of combusted fresh air mixed with the fuel to achieve a given (e.g.,stoichiometric) combustion.

[0005] Engine load is often estimated using a mass air flow sensor. Assuming a known fuel energy content, an estimate of the engine load can be calculated. Once the engine load has been estimated, the corresponding in-cylinder pressure can be easily calculated. However, if the fuel energy content changes, the calculated in-cylinder pressure may be inaccurate. This can reduce engine performance and / or cause engine damage.

[0006] There is a need to find a solution to the problems mentioned above in order to improve engine operation and suppress knocking.

[0007] US 6 748 922 B2 discloses a knock control device for internal combustion engines, the knock control device comprising a frequency magnitude calculation unit including a frequency magnitude detector for detecting the magnitude of a specific frequency based on an output of an ion current detector, an ion current area calculation unit for calculating an ion current area in a predetermined range during the combustion stroke of an affected cylinder based on the output of the ion current detector, a correction unit for correcting the detected specific frequency magnitude based on the calculated ion current range, a knock determination unit for determining whether the engine is knocking based on the corrected specific frequency magnitude, and a control parameter correction amount setter for setting a correction amount for an ignition timing control parameter based on the determination result.

[0008] US 6 230 546 B1 discloses a method and a device for detecting knocking combustion in an internal combustion engine by evaluating the ion current signal detected in the combustion chamber, which are allegedly designed to correct or compensate the ion current signal for longer-term deviations arising therein, for example due to changes in the composition of the fuel as a result of contamination with metallic components or the like.

[0009] US 2003 / 0 183 195 A1 discloses an ion current intensity determined by an ion current intensity learning device for determining the ion current intensity based on an output of an ion current detection circuit, in which at least one of a comparison reference value of a unit for setting a comparison reference value and a control parameter correction amount of a unit for setting a control parameter correction request amount is corrected, so that even when the fuel is mixed with additives and in a case where no standard spark plug is installed, the ion current amount fluctuation is accurately determined even when the amplitude of a knock signal changes due to an ion current intensity fluctuation, and a correction of the comparison reference value according to the ion current intensity or a correction of the control parameter is performed,to prevent erroneous control based on erroneous knock detection and to safely achieve excellent knock detection status and knock control status.

[0010] US 2012 / 0 291 524 A1 relates to a device for analyzing a cylinder-by-cylinder performance of an internal combustion engine, comprising means for measuring the ion current, which are provided to measure an ion current in an engine.

[0011] EP 1 130 254 A1 discloses a method for knock detection in an internal combustion engine by detecting an ion current flowing in a cylinder of the internal combustion engine with the onset of combustion taking place therein and evaluating a knock component based on an assessment value, wherein the knock component is obtained on the basis of a predetermined frequency component superimposed on the ion current, comprising the steps of: determining a peak value of the ion current, calculating a reference value by correcting the determined peak value of the ion current using functions based on the peak value and a current component that approximates the value of the knock component in a knock-free operating state, and determining the assessment value based on the calculated reference value

[0012] DE 103 13 558 A1 discloses a technique in which, based on an ion current intensity determined by an ion current intensity learning means for determining the ion current intensity and based on an output from an ion current detection circuit, at least one of a comparison reference value of a comparison reference value setting means and a control parameter correction amount of a control parameter correction request amount setting means is corrected, so that even in a case where fuel is mixed with additives and a case where a non-standard spark plug is mounted, the ion current amount fluctuation is accurately determined even if the amplitude of a knock signal varies due to ion current intensity fluctuation, and a correction of the comparison reference value, corresponding to the ion current intensity, or a correction of the control parameter is performed, thereby preventing erroneous control,based on faulty knock detection, and to safely achieve an excellent knock detection status and knock control status. Disclosure of the invention

[0013] An object of the present invention is to eliminate or at least minimize the problems described above. This object is achieved by a method and systems according to the appended independent claims. Developments are presented in the dependent claims. Accordingly, the operation of the engine can be controlled more finely and in a more appropriate manner, allowing the ignition timing to be adjusted to achieve more efficient combustion.

[0014] A method for controlling the performance of an engine comprises a) detecting a first signal representing an ion current from an ion sensor that detects a combustion process in a cylinder of the engine, b) calculating a knock index based on the first signal, c) determining an operating state of the engine during the combustion process, preferably on the basis of a sensor that detects the operating state and / or a map describing the operating state, preferably on the basis of an engine map including a speed of the engine and a load of the engine during the combustion process, d) determining an expected knock intensity that describes a permissible intensity of a knock process during the combustion process, e) selecting one or more multipliers based on the operating state, wherein a multiplier is preferably at least one of: a. calculated from data provided by the sensor detecting the operating condition, preferably the ion sensor and / or a fuel quality sensor and / or a temperature sensor and / or a contamination sensor, and b. selected from a table comprising the characteristic map, preferably an engine characteristic map, preferably a characteristic map of speed and load; f) Calculate: a. a knock auxiliary value based on the knock index and the one or more multipliers, wherein preferably the knock index is multiplied by at least one of the multipliers, and / or b. a knock intensity auxiliary value based on the expected knock intensity and the one or more multipliers, preferably wherein at least one expected knock intensity is divided by at least one of the multipliers; g) Compare: a. the calculated knock auxiliary value with the expected knock intensity, and / or b) the knock index with the knock intensity auxiliary value to determine a deviation, and h) correcting the engine operation, preferably adjusting an ignition timing and / or a fuel injection, if the deviation exceeds a threshold indicating that a correction is necessary.

[0015] The method further comprises a. repeating steps a) to f) for at least 2 combustion processes, preferably at least 4 combustion processes, preferably at least 10 combustion processes, preferably at least 50 combustion processes, before correcting the operation in step g), and b. wherein the comparing comprises comparing an average value of the knock index and / or the knock auxiliary value and / or the knock intensity auxiliary value over the repeated combustion processes.

[0016] By incorporating information from the multipliers into the knock index (to calculate the knock auxiliary value) or into the expected knock intensity (to calculate the knock intensity auxiliary value), a more accurate representation of the actual intensity of the measured knock can be generated. By scaling a measured value according to the operating condition and comparing the scaled value to an expected value (or alternatively, scaling the expected value and comparing this value to the measured value), a deviation (between these values) that is solely related to changes in the operating condition can be reduced. As a result, an actual deviation may be more representative of actual knock (which therefore requires correction) than a deviation due to differences in operating conditions.

[0017] The method preferably comprises calculating a peak amplitude of the first signal and / or an integral of at least a portion of the first signal, preferably an integral between a first time and a second time. The first signal is preferably transformed into the frequency domain (e.g., using Fourier or Laplace transforms), band-pass filtering the transformed signal (to remove signals outside a band or range), and determining an amplitude and / or an integral area beneath the filtered, transformed signal. A knock index is preferably calculated from a peak position of a peak in the first signal (and / or the transformed first signal).

[0018] In some cases, a gain of an amplifier may be controlled in response to an operating condition. A method preferably includes comparing the first signal to a saturation limit of the amplifier, and adjusting a gain of the amplifier in response to a difference between an amplitude of the first signal and the saturation limit.

[0019] A multiplier preferably comprises first data from a sensor detecting an operating condition of the engine (e.g., an ion sensor, a fuel quality sensor, a pollution sensor, an EGR sensor, an A / F sensor, and the like) and second data selected from a map describing the operating condition (e.g., a parameter selected from a parameter table, each parameter being related to a particular combination of speed and load).

[0020] A system comprises a processor (e.g., in an engine control unit or an ignition control unit) configured to control operation of an engine and configured to calculate a first signal from a first ion current measured by the ion sensor; b. an ion sensor communicating with the processor, wherein the ion sensor is configured to detect an ion current in a cylinder of the engine during a combustion event and to transmit the ion current to the processor; c. a computer-readable, non-transitory storage medium coupled to a memory and the processor, the storage medium carrying instructions executable by the processor to perform one or more of the methods described in this application.

[0021] A system preferably includes a processor configured to receive a first signal from an ion sensor configured to measure ion current during a combustion event in a cylinder of the engine and to calculate a knock index from the first signal.The processor may determine an expected knock intensity for the combustion event, determine an operating condition of the engine during a combustion event, and: combine the knock index with one or more multipliers to determine a knock assist value, wherein the multipliers are based on the operating condition and the knock assist value represents a knock index that has been normalized with respect to the operating condition, and / or combine the expected knock intensity with one or more multipliers to determine a knock intensity assist value, wherein the multipliers are based on the operating condition and the knock intensity assist value represents an expected knock intensity that has been normalized with respect to the operating condition. The system may be configured to compare: a. the calculated knock auxiliary value with the expected knock intensity; and / or b. the knock index with the knock intensity auxiliary value to determine a deviation and to correct the operation of the engine, preferably to adjust an ignition timing and / or a fuel injection if the deviation exceeds a threshold indicating that a correction is necessary.

[0022] A system preferably includes a sensor configured to detect the operating state of the engine, which may include the ion sensor configured to detect the ion current. A system preferably includes an ion sensor and another sensor configured to detect the operating state, and in some cases, a multiplier is calculated based on both sensors. The sensor preferably includes a fuel quality sensor, a contaminant sensor, an A / F sensor, an EGR sensor, a temperature sensor, and the like.

[0023] The system preferably includes an amplifier and a gain control feedback circuit. The circuit preferably incorporates operating condition data and / or ion current data to determine a gain of the amplifier. In some cases, a gain of the amplifier is preferably adjusted according to the engine operating condition. In some cases, a value of the first signal is preferably compared to a saturation limit of the amplifier, and the gain is adjusted in response (e.g., increased if the signal is too weak or decreased if the signal saturates the amplifier). The gain is preferably adjusted in response to a map (e.g., an engine map, such as an engine map including speed and load). Various systems can be configured to perform the disclosed methods.

[0024] Thanks to the method according to the invention, a variety of factors relating to the operation of the engine, such as fuel quality, EGR, ignition timing, air / fuel ratio (A / F) are taken into account when determining the cylinder pressure, thereby achieving a more reliable and accurate value for this cylinder pressure than would be the case if the calculations were based solely on load and speed (revolutions per minute, rpm) of the engine.

[0025] The engine characteristic determined by the method is preferably calculated for several cycles, preferably at least four, and a mean (or average) "comprehensive" engine characteristic is calculated. The determined offset can be more stable and accurate with such averaging.

[0026] The first signal based on an ion current of the cylinder is preferably maintained at a desired level by determining a peak amplitude of the signal and using a gain control.

[0027] The peak position of the first signal is preferably determined, which provides information regarding fuel quality and allows an offset to increase fuel efficiency and further optimize cylinder pressure and eliminate knock.

[0028] Further aspects and advantages of the invention will be readily apparent to those skilled in the art from the detailed explanation below. Brief description of the drawings

[0029] The present invention will now be described in more detail with reference to the accompanying drawings, in which: Fig. 1 shows a schematic view of a preferred embodiment of the system of the present invention; and Fig. 2 a more detailed schematic view of the system Fig. 1 shows. Detailed description of the invention

[0030] Various systems (e.g., controllers and the like) include a computer-readable, non-transitory storage medium coupled to a processor and a memory. Executable instructions stored on the medium and / or memory may be executed by the processor to perform one or more methods. A processor may be incorporated into an ignition control unit or an engine control unit, and / or may be a discrete component. The examples described in this application are for illustrative purposes only and are not intended to be limiting.

[0031] Fig. 1 discloses a control system 1 for controlling the operation of an engine, comprising an ignition controller 2 operable to control at least one spark plug unit 4 to generate an ignition spark in a cylinder of the engine, according to some embodiments. A processor (e.g., in the ignition controller 2) receives information from the spark plug unit in the form of a first signal corresponding to an ion current and uses this signal to determine a knock index, as will be explained in more detail below. The knock index may represent a measured intensity of a knock event during the measured combustion event. For example, a knock intensity may range from "minimal" through "low" and "medium" to "high" and finally "damaging."

[0032] Since knocking represents a pressure event within the cylinder, the knock index is used as input to an electronic engine control unit (ECU) 3, in which an operating condition (e.g., an engine index) related to the cylinder pressure of the cylinder is determined, as will also be explained in more detail below. This operating condition / engine index is used to determine an offset or correction suitable for further optimizing engine operation. This offset / correction is fed back (e.g., to the ignition control unit 2), which provides a feedback input to the spark plug unit 4 to change the ignition timing according to the feedback input.The ignition control unit 2 and the engine control unit (ECU) 3 may be different components that perform the tasks described here, but may also form a unit or a plurality of units that communicate with each other to arrive at the correction required to optimize the operation of the engine.

[0033] In some cases, a sensor 5 is used to detect an operating condition of the engine. The sensor 5 may include an ion sensor, which may be integrated into the spark plug unit 4. The sensor 5 may include a fuel quality sensor, a humidity sensor, a pollution sensor, an air quality sensor, an EGR sensor, an A / F sensor, and / or any other sensor configured to detect an operating condition of the engine.

[0034] Fig. Figure 2 discloses the control system 1 in more detail, with the ignition control unit 2, which serves to control at least one spark plug unit 4 with a coil 41 to generate an ignition spark at a spark plug 42. A processor (e.g., in the ignition control unit 2) is configured to detect an ion current in a cylinder of the engine in the form of a first signal and to analyze this first signal to determine a knock index describing an intensity of a knocking event in the cylinder, which can describe the operation of the engine and the cylinder, in particular at a given combustion instant, and according to a specific operating condition.

[0035] The knock index is then analyzed (e.g., by the electronic engine control unit ECU 3) and is combined with a series of multipliers (e.g., multiplied by one or more multipliers) associated with the operating condition at a given time (e.g., a combustion event) for the engine. A multiplier may be selected from a table (e.g., a map, such as an engine map including speed, load, and a value for one or more multipliers for each combination of speed and load). A multiplier may be calculated from a sensor configured to detect the operating condition. In some cases, a multiplier comprises a first parameter selected from a table (comprising the operating condition) and a second parameter calculated from data provided by the sensor (detecting the operating condition).The sensor may be a different sensor than the ion sensor. The sensor may be the same sensor as the ion sensor. The operating condition may be used to determine an expected knock intensity for that combustion cycle. The expected knock intensity may be a variety of values ​​(e.g., low, medium, high) representing an "acceptable" or "expected" knock intensity. For example, an expected knock intensity at low load may be a "low intensity," while an expected knock intensity at high load would be a "high intensity."

[0036] The operating condition (as represented by the one or more multipliers) may be used to "scale" or "normalize" a value to improve the accuracy with which a measured value is compared to an expected value (for example, to determine an engine characteristic that reflects the cylinder pressure at that time). The multipliers may be used to "normalize" or otherwise scale values ​​according to the operating condition. In some cases, the knock characteristic (based on the first signal) is scaled according to the multiplier. For example, an operating condition that can be associated with a high expected knock intensity may have a large multiplier, whereas an operating condition that can be associated with a low knock intensity may have a small multiplier.Multiplying the calculated knock index by the respective multiplier can "scale" the knock index to a value that represents an auxiliary value for the operating condition. A knock index modified by the multiplier can be described as an auxiliary knock value. The auxiliary knock value can be compared to an expected knock intensity (e.g., for this operating condition) to determine whether a correction is necessary.

[0037] In some embodiments, a knock intensity assist value may be calculated. The knock intensity assist value may include an expected knock intensity, which may be modified (e.g., divided) by one or more multipliers representing the operating condition. The knock intensity assist value may be compared to the knock index. If the knock index exceeds the knock intensity assist value (e.g., knock is too intense), the engine may be adjusted (e.g., throttled down). If the knock index is well below the knock intensity assist value (indicating that knock could be safely increased), power may be increased (e.g., the engine may be "uptuned").

[0038] In some cases, using sensitivity data specific to the engine itself, it can be determined whether the cylinder's operation needs to be adjusted and, if so, how.

[0039] Control system 1 will now be explained in more detail. The cylinder ion current signal will be referred to throughout the text as the first signal, and similarly, the knock index signal provided as input to the processor will be referred to as the second signal, although in some cases these signals may have been modified by filtering or other analysis, or combined with a series of multipliers.

[0040] As previously stated, the control system 1 includes an ignition controller 2, an engine control unit (ECU) 3, and a spark plug unit 4. However, it should be noted that the control system 1 may preferably include multiple spark plug units 4 and, if appropriate, multiple ignition controllers 2, so that the operation of each cylinder in the engine can be controlled by the system and method according to the present invention. In some embodiments, comparisons are made based on an average value across a plurality of cylinders and / or over a period of time (e.g., a plurality of combustion events).

[0041] An ion current is detected in the form of a first signal by an ion current detector 21, preferably in the form of a first sensor 21 of the ignition control unit 2. To facilitate subsequent analysis, the first signal may undergo gain control by the gain controller 22 using a feedback loop in which the first signal passes through a first filter 221 to low-pass filter the first signal, a peak detector 222, and a constant level controller 223 to reduce noise, detect a peak of the first signal, and determine a gain level suitable for maintaining the amplitude of the first signal at a predetermined level. One method may include determining an amplitude of at least a portion of the first signal and adjusting the applied gain according to the amplitude.If the first signal saturates the amplifier, for example, the gain can be reduced. If the amplitude of the first signal is too small, the gain can be increased. Preferably, the gain control is adjusted such that the portion of the first signal used to determine the knock index (e.g., a window in the time or frequency domain) has an amplitude that lies between 20% and 50%, including between 25% and 40%, including approximately 33% of full scale. This simplifies subsequent analyses, and the determined knock index can be more easily combined with multipliers that describe the engine conditions, as explained in more detail below.

[0042] By adjusting the gain control 22 in this way, the amplitude of the first signal can be maintained at a suitable level. The first signal then passes through a second filter 23, where it is filtered in a suitable manner to enable the knock index calculation unit 24 to determine the knock index. The filtering performed can be bandpass filtering, which preserves only frequencies of a desired interval, suitably approximately 3 to 14 kHz, but can also be performed in the time dimension, so that only an interval corresponding to a portion of the crankshaft revolution is preserved, preferably from the top dead center position (TDC) to approximately 40°-50° after the top dead center position TDC, or from the top dead center position TDC until the signal has reached an order of magnitude below a predetermined level, for example, approximately 1% of the peak value, and can thus be considered extinct.Then, the knock index is determined using a suitable method as is well known in the art, and a second signal corresponding to this knock index is transmitted to the engine control unit ECU 3 for further analysis.

[0043] The second signal (e.g., corresponding to the knock index) can be transformed into an engine index, a knock auxiliary value, and / or a knock intensity auxiliary value in an engine index converter 31 by multiplying it by a first multiplier from a map (e.g., corresponding to the current engine speed (rpm) or load). The first multiplier can be selected from the map (corresponding to the speed and load during this combustion cycle) and applied as a multiplier to the second signal corresponding to the knock index. The first multiplier can be derived from an input from a first sensor (e.g., sensor 5, Fig. 1) can be calculated.

[0044] The resulting engine index, knock assist value, and / or knock intensity assist value calculated by the engine index converter 31 generally provides an indication of the cylinder pressure during the cycle in which the first signal (corresponding to the ion current of that cylinder) was generated. This indication can be used to determine whether the engine's operation, particularly the cylinders and the ignition spark provided to ignite the fuel, should be corrected in any way to improve the engine's operating conditions.

[0045] In some embodiments, to arrive at a more comprehensive engine index, a series of adjustments are performed, wherein the engine index / knock assist value / knock intensity assist value of the second signal is multiplied by a series of multipliers corresponding to various operating conditions of the engine. For example, a second multiplier 32 may correspond to ignition timing, i.e., the position of the crankshaft at the time of ignition. A third multiplier 33 may correspond to variations in the air / fuel ratio (i.e., lambda), a fourth multiplier 34 may correspond to variations in EGR (i.e., exhaust gas recirculation), and a fifth multiplier 35 may correspond to variations in fuel quality. The resulting comprehensive engine index (CEI) is stored by an averaging memory system 36.An average engine index and / or an average comprehensive engine index CEI (or average knock auxiliary value or average knock intensity auxiliary value, as appropriate) may be calculated over several strokes, preferably 2 to 100, inclusive, 4 to 80, inclusive, 10 - 50 strokes.

[0046] The average value can be compared (e.g., with a knock sensitivity 37, which may represent an expected knock intensity) to determine whether a correction is required for engine operation, and if so, the required modification is determined in an offset determination unit 38. During standard engine operation, the offset determination unit 38 indicates an adjustment of the ignition timing of one or more cylinders to eliminate knocking. In some cases, the desired offset may also be used to change the fuel mixture in one or more cylinders to act as a cylinder coolant in cases where an adjustment of the ignition timing alone cannot eliminate knocking.

[0047] The offset determination unit 38 is combined with ignition data from an ignition map 51 in a summing device 5 to arrive at the desired change in ignition timing 52. This change is provided as an output of the ECU 3 and input to the ignition control unit 2, where a coil driver 25 drives the coil(s) of the spark plug unit 4. Thus, the offset determined by the control system 1 is fed back to the spark plug unit 4 to control the ignition timing. If a fuel mixture offset is also used, this is also provided as an output of the ECU 3 to appropriate components of the engine (not shown).

[0048] When analyzing the ion current (e.g., in the ignition control unit 2), the position and amplitude of the peak of the first signal can also provide information regarding the combustion rate in the cylinder, indicating the need for corrections to optimize fuel efficiency and further influence cylinder pressure. Thus, by analyzing the signal to determine differences compared to the ignition map (e.g., a representation of expected values ​​for these parameters in an operating condition) that indicates normal engine operation, it can be determined whether further correction of the fuel mixture is desired or whether the ignition timing should be further adjusted to enable optimized engine operation.This analysis may take place in the ignition control unit 2 or the ECU 3 or in both, and the results of the analysis may be taken into account when determining the offset, which is also based on the engine characteristic indicating the cylinder pressure, as also described above.

Claims

[1] A method for controlling the power of an engine, comprising: a) detecting a first signal representing an ion current from an ion sensor that detects a combustion process in a cylinder of the engine; b) calculating a knock index based on the first signal; c) determining an operating state of the engine during the combustion process, preferably on the basis of a sensor detecting the operating state and / or a characteristic map describing the operating state, preferably on the basis of an engine characteristic map including a speed of the engine and a load of the engine during the combustion process; d) determining an expected knock intensity which describes a permissible intensity of a knocking process during the combustion process; e) selecting one or more multipliers based on the operating state, wherein a multiplier is preferably at least one of: a. calculated from data provided by the sensor detecting the operating condition, preferably the ion sensor and / or a fuel quality sensor and / or a temperature sensor and / or a contamination sensor, and b. selected from a table comprising the characteristic map, preferably an engine characteristic map, preferably a characteristic map of speed and load; f) Calculate: a. a knock auxiliary value based on the knock index and the one or more multipliers, wherein preferably the knock index is multiplied by at least one of the multipliers, and / or b. a knock intensity auxiliary value based on the expected knock intensity and the one or more multipliers, wherein preferably at least one expected knock intensity is divided by at least one of the multipliers; g) repeating steps a) to f) for at least two combustion processes, preferably at least 4 combustion processes, preferably at least 10 combustion processes, preferably at least 50 combustion processes; h) Compare: a. the calculated knock auxiliary value with the expected knock intensity, and / or b. the knock index with the knock intensity auxiliary value, to determine a deviation, wherein the comparing comprises comparing an average value of the knock index and / or the knock auxiliary value and / or the knock intensity auxiliary value over the repeated combustion processes; and i) generating an instruction to correct the operation of the engine, preferably to adjust ignition timing and / or fuel injection, if the deviation exceeds a threshold indicating that a correction is required. [2] The method of claim 1, wherein calculating the knock index comprises calculating: a. a peak amplitude of the first signal, and / or b. an integral of at least a portion of the first signal, preferably an integral between a first time and a second time. [3] Method according to claim 1 and / or 2, wherein calculating the knock index comprises: a. Transforming the first signal into the frequency domain; b. bandpass filtering the first signal; and c. Determining an amplitude of the bandpass-filtered, transformed first signal and / or an integral area of ​​at least a portion of the bandpass-filtered, transformed first signal. [4] A method according to any one of claims 1 to 3, further comprising: a. comparing the first signal with a saturation limit of an amplifier configured to amplify the first signal; and b. Adjusting a gain of the amplifier in response to a difference between an amplitude of the first signal and the saturation limit. [5] A method according to any one of claims 1 to 4, wherein the one or more multipliers are selected from an engine map based on at least two of the following metrics: engine load, revolutions per minute, rpm, fuel quality, exhaust gas recirculation, EGR, timing, and A / F, air / fuel ratio. [6] A method according to any one of claims 1 to 5, wherein calculating the knock index comprises determining a peak position of the first signal and / or the transformed first signal. [7] The method of any one of claims 1 to 6, wherein calculating the knock index comprises transforming the first signal into a frequency domain and determining a peak position of a peak in the transformed first signal. [8] Method according to one of claims 1 to 7, wherein determining the operating state comprises selecting a first parameter from an engine map and measuring a second parameter from at least one sensor detecting the operating state. [9] A method according to any one of claims 1 to 8, wherein the at least one operating condition detecting sensor includes a fuel quality sensor, a fuel impurity sensor, a temperature sensor, a humidity sensor, an EGR sensor, an A / F sensor, and a pressure sensor. [10] Method according to one of claims 1 to 9, wherein the sensor detecting the operating state comprises the ion sensor detecting the combustion process. [11] Method according to one of claims 1 to 10, wherein a first multiplier is selected from a table comprising the operating state, and a second multiplier is calculated from data provided by the sensor detecting the operating state. [12] The method of claim 11, further comprising adjusting a gain of an amplifier configured to amplify the first signal, wherein the adjusting comprises scaling the gain using the first and second multipliers. [13] System (1), comprising: a. an engine control unit, ECU, (3) having a processor configured to control the operation of an engine, the ECU being configured to calculate a first signal from an ion current measured by an ion sensor (5); b. an ion sensor (5) communicating with the ECU, the ion sensor being configured to detect an ion current in a cylinder of the engine during a combustion process and to transmit the ion current to the ECU; c. a computer-readable, non-transitory storage medium coupled to a memory and the processor, the storage medium carrying instructions executable by the processor to perform a method according to any one of claims 1 to 12. [14] A system (1) for controlling an operation of an engine, the system comprising: • an ion sensor (5) configured to detect a combustion process within a cylinder of the engine; • a processor that communicates with the ion sensor, preferably a processor in an ignition control unit and / or an engine control unit (3), • a memory that communicates with the processor and is configured to store instructions executable by the processor, and • a non-volatile storage medium in communication with the memory and processor, the medium carrying processor-executable instructions to perform a method comprising: a) receiving a first signal representing an ion current from the ion sensor; b) calculating a knock index based on the first signal; c) determining an operating state of the engine during the combustion process, preferably on the basis of a sensor detecting the operating state and / or a characteristic map describing the operating state, preferably on the basis of an engine characteristic map including a speed of the engine and a load of the engine during the combustion process; d) determining an expected knock intensity that describes a permissible intensity of a knocking process during a combustion process; e) selecting one or more multipliers based on the operating state, wherein a multiplier is preferably at least one of: a. calculated from data provided by the sensor detecting the operating condition, preferably at least one ion sensor and / or a fuel quality sensor and / or temperature sensor and / or contamination sensor, and b. selected from a table comprising the characteristic map, preferably an engine characteristic map, preferably a characteristic map of speed and load; f) Calculating c. the knock auxiliary value based on the knock index and the one or more multipliers, wherein preferably the knock index is multiplied by at least one of the multipliers, and / or d. a knock intensity auxiliary value based on the expected knock intensity and the one or more multipliers, preferably wherein at least one expected knock intensity is divided by at least one of the multipliers; g) repeating steps a) to f) for at least two combustion processes, preferably at least 4 combustion processes, preferably at least 10 combustion processes, preferably at least 50 combustion processes h) Compare: e. the calculated knock auxiliary value with the expected knock intensity, and / or f. the knock index with the knock intensity auxiliary value, to determine a deviation, wherein the comparing comprises comparing an average value of the knock index and / or the knock auxiliary value and / or the knock intensity auxiliary value over the repeated combustion processes; and i) Correcting engine operation, preferably adjusting ignition timing and / or fuel injection, if the deviation exceeds a threshold indicating that correction is necessary. [15] The system of claim 13 and / or 14, further comprising a sensor configured to detect an operating condition of the engine, preferably a further sensor in addition to the ion sensor. [16] The system of any one of claims 13 to 15, further comprising an amplifier coupled to the ion sensor, the amplifier configured to amplify the first signal. [17] The system of claim 16, wherein the amplifier comprises a gain control circuit configured to to determine an operating state of the motor and / or a saturation level of the first signal, and to adjust the amplifier gain according to the operating condition and / or the saturation level. [18] The system of claim 17, wherein the gain control circuit is configured to adjust the gain according to a speed and load of the motor. [19] The system of any one of claims 13 to 18, wherein the processor is configured to perform a method according to any one of claims 1 to 12.

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