An octane number prediction method and device based on knock pressure amplitude response behavior and multi-feature fusion

Abstract

This disclosure provides a method and apparatus for predicting octane number based on knock pressure amplitude response behavior and multi-feature fusion. The method includes the following steps: extracting knock-related amplitude features characterizing the degree of abnormal high-frequency pressure oscillations during combustion; progressively adjusting the engine compression ratio to induce differences in the knock response of the fuel under different compression ratio conditions; constructing a response behavior descriptor of the knock-related amplitude features as a function of the compression ratio based on the knock response differences; constructing multiple knock-related features based on the response behavior descriptor, and fusing these features to obtain a comprehensive knock response index; and predicting the anti-knock performance of the fuel based on the comprehensive knock response index. This disclosure improves the stability of the anti-knock performance prediction results, more accurately assesses the anti-knock performance of fuel in actual engines, and is applicable to high-octane fuels and oxygenated additive fuel systems, demonstrating strong engineering applicability.

Description

Technical Field

[0001] This disclosure relates to the field of energy and power engineering technology, and in particular to a method and apparatus for predicting octane number based on detonation pressure amplitude response behavior and multi-feature fusion. Background Technology

[0002] The anti-knock performance of fuel is one of the key factors affecting the further improvement of thermal efficiency of spark-ignition engines. Most existing solutions based on in-cylinder pressure rely on a single knock feature to establish a correlation model, such as the maximum amplitude of knock pressure or the integral intensity of pressure oscillation. These solutions suffer from problems such as a single feature dimension, sensitivity to changes in operating conditions, and limited model generalization ability. Furthermore, they usually require preset knock thresholds or dynamic adjustment of the compression ratio, making it difficult to effectively evaluate different fuel systems while ensuring stability. Summary of the Invention

[0003] This disclosure provides an octane number prediction method based on knock pressure amplitude response behavior and multi-feature fusion. The method includes the following steps: extracting knock-related amplitude features characterizing the degree of abnormal high-frequency pressure oscillations during combustion; progressively adjusting the engine compression ratio to induce differences in the knock response of the fuel under different compression ratio conditions; constructing a response behavior descriptor of the knock-related amplitude features as a function of the compression ratio based on the knock response differences; constructing multiple knock-related features based on the response behavior descriptor, and fusing the multiple knock-related features to obtain a comprehensive knock response index; and predicting the anti-knock performance of the fuel based on the comprehensive knock response index.

[0004] In some embodiments, extracting knock-related amplitude features characterizing the degree of abnormal high-frequency pressure oscillations during combustion includes: acquiring in-cylinder combustion pressure signals for multiple combustion cycles under preset stable operating conditions; and analyzing the in-cylinder combustion pressure signals to extract the knock-related amplitude features characterizing the degree of abnormal high-frequency pressure oscillations during combustion.

[0005] In some embodiments, adjusting the engine compression ratio stepwise includes adjusting the engine compression ratio while keeping the other operating conditions of the engine substantially unchanged.

[0006] In some embodiments, the response behavior descriptor is represented as the rate of change of the knock-related amplitude feature relative to the change in compression ratio, used to characterize the knock sensitivity of the fuel to changes in compression ratio. The response behavior descriptor R is represented as: Where A represents the knock-related amplitude characteristics, and CR represents the engine compression ratio.

[0007] In some embodiments, the various knock-related features are high-frequency pressure oscillation amplitude features extracted from in-cylinder combustion pressure signals.

[0008] In some embodiments, the plurality of knock-related features include at least two of the following features: knock-related amplitude level, amplitude fluctuation degree, descriptive quantity of the response behavior of knock-related amplitude features as a function of compression ratio, and knock occurrence rate.

[0009] In some embodiments, the comprehensive detonation response index is obtained by performing dimensionless processing on the multiple detonation-related features and then using a weighted fusion method. The comprehensive detonation response index is expressed as follows: in, The i-th type of detonation-related feature after normalization; The corresponding weight coefficients, and satisfying =1.

[0010] In some embodiments, the weighting coefficients in the weighted fusion are either preset weighting coefficients or weighting coefficients determined based on historical test data.

[0011] This disclosure also provides an octane number prediction device based on knock pressure amplitude response behavior and multi-feature fusion. The octane number prediction method according to this disclosure is used to predict the anti-knock performance of fuel. The octane number prediction device includes an in-cylinder pressure sensor and a data analysis system. The in-cylinder pressure sensor collects combustion pressure signals in real time, and the data analysis system performs signal processing.

[0012] In some embodiments, the device further includes an electronically controlled fuel injection system, which includes a pressure control switch and a pressure gauge disposed on the fuel line and fuel injectors connected to an electronic control unit, so as to realize real-time monitoring and precise adjustment of fuel pressure.

[0013] The method disclosed herein can more accurately assess the anti-knock performance of fuel in actual engines by adjusting the compression ratio to induce fuel knock response behavior; it adopts a multi-feature fusion approach to reduce the randomness and instability caused by a single knock feature; it avoids directly predicting anti-knock performance based on a single knock amplitude, improving the stability of the prediction results, thereby more accurately assessing the anti-knock performance of fuel in actual engines; it is applicable to high-octane fuels and oxygenated additive fuel systems, and has strong engineering applicability. Attached Figure Description

[0014] Figure 1 This is a schematic block diagram of an octane number prediction method based on detonation pressure amplitude response behavior and multi-feature fusion, according to an embodiment of this disclosure.

[0015] Figure 2 This is a schematic block diagram of an octane number prediction device based on detonation pressure amplitude response behavior and multi-feature fusion according to an embodiment of this disclosure.

[0016] Figure 3 This is a schematic structural diagram of an octane number prediction device based on detonation pressure amplitude response behavior and multi-feature fusion according to an embodiment of this disclosure.

[0017] Explanation of reference numerals in the attached figures: 1. High-pressure nitrogen cylinder; 2. High-pressure gas line; 3. Fuel tank; 4. Pressure gauge; 5. Fuel line; 6. Pressure control switch; 7. Fuel injector; 8. Intake pipe; 9. Exhaust pipe; 10. Cooling device; 11. Intake heating jacket; 12. Thermocouple; 13. Electronic control unit (ECU); 14. Octane number tester; 15. Ignition device; 16. Cylinder pressure sensor; 17. Combustion analyzer; 18. Oxygen sensor; 19. Lambda analyzer; 20. Data analysis system; 21. Engine combustion chamber; 22. Intake valve; and 23. Cylinder structure. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions of this disclosure, the technical solutions of this disclosure will be described in detail below with reference to the accompanying drawings.

[0019] Exemplary embodiments will be described more fully below with reference to the accompanying drawings; however, these exemplary embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will enable those skilled in the art to fully understand the scope of this disclosure.

[0020] Where there is no conflict, the various embodiments of this disclosure and the features thereof in the embodiments may be combined with each other.

[0021] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated entries.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the stated feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded.

[0023] The embodiments described herein can be described with reference to plan views and / or cross-sectional views using the ideal schematic diagrams of this disclosure. Therefore, the example illustrations can be modified according to manufacturing techniques and / or tolerances. Therefore, the embodiments are not limited to those shown in the drawings, but include modifications to configurations formed based on manufacturing processes. Therefore, the areas illustrated in the drawings are schematic in nature, and the shapes of the areas shown in the figures illustrate specific shapes of areas of an element, but are not intended to be limiting.

[0024] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted as having an idealized or overly formal meaning, unless expressly so defined herein.

[0025] Technical Terminology Explanation Unless otherwise specified in this disclosure, the following technical terms shall be interpreted as follows: "Knock," also known as engine knock or combustion knocking, is a malfunction caused by abnormal combustion in an engine. Knock typically occurs when, after the fuel-air mixture ignites in the combustion chamber, the flame has not fully propagated, and unburned fuel-air mixture at a distance spontaneously combusts due to high temperature or pressure. The resulting flame collides with the normally burning flame, generating immense pressure. This phenomenon can easily damage the engine.

[0026] The "knock window" refers to the crankshaft rotation angle range (window) after the compression top dead center where knocking occurs. Knock is determined to have occurred only when the vibration intensity of the cylinder block exceeds the limit within this window.

[0027] Compression ratio is the ratio of the total volume of the engine cylinders to the volume of the combustion chamber. It indicates the degree to which the gas inside the cylinder is compressed as the piston moves from bottom dead center to top dead center. A higher compression ratio results in higher pressure and temperature of the gas inside the cylinder at the end of compression.

[0028] "Anti-knock performance" refers to the characteristic of fuel to resist knocking during engine combustion, and is a key indicator for measuring fuel combustion efficiency.

[0029] Octane rating is a core indicator for measuring fuel's anti-knock performance; a higher number indicates more stable combustion of the fuel in the engine. Engines with high compression ratios have higher combustion chamber pressures, making them more prone to knocking if fuel with low anti-knock properties is used.

[0030] "Reference fuel" is a key substance used for standardized evaluation of fuel performance, especially in the petroleum product sector, where it serves as a calibration reference to quantify key indicators such as octane number and cetane number.

[0031] The "fuel equivalence ratio" (φ) is the ratio of the proportion of fuel to air in an actual fuel-air mixture to the theoretical stoichiometric ratio. It is used to measure the degree to which combustion deviates from complete combustion.

[0032] The Electronic Control Unit (ECU) is primarily responsible for the engine's operation control. It collects engine status information through sensors such as oxygen sensors and knock sensors, and precisely controls fuel injection quantity, ignition advance angle, and idle speed to ensure the engine's power output and fuel economy under different operating conditions.

[0033] A "Lambda analyzer" is an instrument used to accurately measure the air-fuel ratio (AFR) lambda value (λ, the ratio of the actual air-fuel ratio to the stoichiometric ratio) in a gas mixture.

[0034] The "knock sensor" is used to detect whether knocking occurs during engine operation and transmits the knock signal to the engine ECU. The ECU issues a command based on this signal to control the on / off state of the primary circuit of the ignition coil and adjust the ignition timing to prevent knocking from occurring.

[0035] The "detonation criterion" is mainly based on the physical phenomena and measurable parameters generated by detonation, and is used to identify and quantify the degree of detonation.

[0036] "Knock intensity" is an indicator for judging the severity of knocking, including, for example, the integral of the modulus of the pressure oscillation (IMPO) and the maximum amplitude of pressure oscillation (MAPO).

[0037] In this field, current ASTM standard methods for predicting the anti-knock performance of fuels rely on octane rating analyzers equipped with conventional knock sensors. The octane rating of the test fuel is determined by comparing it to a reference fuel. However, this method has gradually revealed certain limitations in practical applications. First, the structure of the octane rating analyzer and its associated knock sensor have limited ability to capture high-frequency pressure oscillations, making it difficult to accurately reflect the true anti-knock performance of fuels under modern high-intensity engine operating conditions. Second, the fuel supply method used in octane rating analyzers differs significantly from the electronically controlled fuel injection systems commonly used in modern engines, leading to a deviation between the measured results and actual engine operating conditions. Furthermore, for fuels with octane ratings higher than 100 and oxygenated additive fuel systems, the traditional octane rating analyzer method is limited by the range of reference fuels and the determination method, restricting its measurement accuracy and applicability. To address these issues, improved technologies have attempted to introduce in-cylinder pressure sensors to evaluate fuel anti-knock performance by analyzing the pressure oscillation characteristics during combustion. However, most existing in-cylinder pressure-based solutions rely on a single knock feature to establish a correlation model, such as the maximum amplitude of knock pressure or the integral intensity of pressure oscillation. These solutions suffer from problems such as a single feature dimension, sensitivity to changes in operating conditions, and limited model generalization ability. Furthermore, they usually require a preset knock threshold or dynamic adjustment of the compression ratio, making it difficult to achieve effective evaluation of different fuel systems while ensuring stability.

[0038] Specifically, existing research and patents on fuel octane number determination can be broadly categorized into three technical approaches.

[0039] The first method is based on high-frequency in-cylinder pressure signals, using knock intensity indicators such as MAPO or IMPO, and combining them with artificially set fixed thresholds to establish a correlation between octane rating and octane rating. The second method is based on knock sensors or characteristic compression ratios, using operating parameters when the engine enters a specific knock state to infer the octane rating. The third method completely departs from the actual engine knock process, using auto-ignition or pressure derivative characteristics in a constant-volume combustion chamber to predict the research octane rating. Although these three methods differ in experimental methods and signal formats, they share a significant commonality in their core assumptions: treating knock criteria or key characteristics as fixed, one-time set parameters.

[0040] Taking the MAPO / IMPO method based on high-frequency cylinder pressure as an example, existing studies typically determine an empirical knock threshold through numerous experiments within a limited octane number range and under specific operating conditions, assuming that this threshold is universally applicable under different fuels and operating conditions. This approach can be considered an effective approximation within the traditional gasoline octane number range. However, when the fuel octane number increases significantly or the engine compression ratio changes, the preconditions implied by the fixed threshold no longer hold, easily leading to the failure of the knock criterion and thus causing systematic biases in the anti-knock performance prediction results. From a methodological perspective, this type of method essentially relies on the mapping relationship of existing calibration data within a limited range, and is closer to an empirical interpolation-type measurement method than a prediction method with adaptive or extrapolation capabilities.

[0041] Patented methods based on knock sensors or characteristic compression ratios also suffer from similar problems. These methods typically rely on a specific knock intensity level or a characteristic operating point to establish an octane number mapping relationship. However, due to the limited ability of knock sensors to capture high-frequency pressure oscillation information, their criteria reflect more the macroscopic knock trend than the actual anti-knock behavior details of the fuel. This means that such methods also need to be recalibrated when the fuel type changes, making it difficult to achieve universal application across fuel systems.

[0042] As for the method of predicting octane number using a constant-volume combustion chamber, its starting point is not the engine knock mechanism, but rather the auto-ignition and chemical reaction kinetics of the fuel. This approach is significant in basic research, but due to the lack of actual engine knock characteristics such as compression ratio changes, flame propagation, and end-gas auto-ignition, its prediction results cannot directly reflect the anti-knock performance of the fuel in a real spark-ignition engine. Therefore, it differs fundamentally from engine knock measurement methods in terms of engineering applicability.

[0043] Due to the numerous problems mentioned above in the prediction methods in this field, there is an urgent need to propose an improved method for predicting anti-knock performance. Starting from the response behavior of detonation pressure oscillation to changes in combustion conditions, a robust fuel anti-knock performance criterion is constructed by combining a multi-feature fusion method to overcome the above-mentioned shortcomings of the prior art, thereby better characterizing the fuel's anti-knock performance under actual engine operating conditions.

[0044] Figure 1 This is a schematic block diagram of an octane number prediction method based on detonation pressure amplitude response behavior and multi-feature fusion, according to an embodiment of this disclosure.

[0045] Firstly, referring to Figure 1This disclosure provides an octane number prediction method based on knock pressure amplitude response behavior and multi-feature fusion. The method includes the following steps: extraction step S102, extracting knock-related amplitude features characterizing the degree of abnormal high-frequency pressure oscillations during combustion; adjustment step S104, adjusting the engine compression ratio stepwise to stimulate differences in the knock response of fuel under different compression ratio conditions; acquisition step S106, constructing a response behavior descriptor of the knock-related amplitude features as a function of the compression ratio based on the knock response differences; fusion step S108, constructing multiple knock-related features based on the response behavior descriptor and fusing the multiple knock-related features to obtain a comprehensive knock response index; and prediction step S110, predicting the anti-knock performance of the fuel based on the comprehensive knock response index.

[0046] This disclosure addresses the aforementioned shortcomings of existing fuel octane number testing systems in terms of adaptability to actual engine operating conditions and evaluation accuracy. It proposes a fuel anti-knock performance prediction method based on the fusion of knock pressure amplitude response behavior and multiple features. This disclosure reconstructs the role of the knock criterion at the methodological level. While keeping other engine operating conditions essentially constant, it obtains the knock response characteristics of fuel under different compression ratios by adjusting the engine compression ratio. Therefore, it no longer treats knock intensity or threshold as a fixed constant, but instead characterizes the response law of knock features changing with operating conditions based on the knock response behavior of fuel under different compression ratios, taking the fuel's knock sensitivity to compression ratio changes as the core modeling object. In this way, the knock criterion is transformed from a manually set empirical parameter into a modelable and predictable physical quantity, fundamentally overcoming the applicability limitations of the fixed threshold method.

[0047] In other words, this disclosure improves upon the fundamental approach of the anti-knock performance testing method. Unlike existing empirical calibration methods based on fixed knock thresholds or single knock intensity parameters such as MAPO / IMPO, this disclosure does not pre-determine a knock criterion. Instead, it adjusts the engine compression ratio to analyze the response behavior of knock characteristics to changes in operating conditions, characterizing the fuel's knock sensitivity to compression ratio variations, and constructing an anti-knock performance prediction model based on this. This method transforms the knock criterion from an empirical constant into a modeling result derived from response behavior, enabling the anti-knock performance testing process to be adaptive and avoiding the problem of traditional interpolation methods failing under changes in fuel type and operating conditions.

[0048] Therefore, this method can more accurately assess the anti-knock performance of fuel in actual engines by adjusting the compression ratio to induce fuel knock response behavior; it adopts a multi-feature fusion approach to reduce the randomness and instability caused by a single knock feature; it avoids directly predicting anti-knock performance based on a single knock amplitude, improving the stability of the prediction results, thereby more accurately assessing the anti-knock performance of fuel in actual engines; it is applicable to high-octane fuels and oxygenated additive fuel systems, and has strong engineering applicability.

[0049] In some embodiments, the extraction step includes: acquiring in-cylinder combustion pressure signals for multiple combustion cycles under preset stable operating conditions; and analyzing the in-cylinder combustion pressure signals to extract the knock-related amplitude features characterizing the degree of abnormal high-frequency pressure oscillations during the combustion process.

[0050] In some embodiments, under the condition that the engine is operating under a preset stable condition, the in-cylinder combustion pressure signal of multiple combustion cycles is continuously collected to characterize the transient pressure change characteristics during the combustion process.

[0051] In some embodiments, analyzing the in-cylinder combustion pressure signal to extract knock-related amplitude features includes performing one of the following analyses on the in-cylinder combustion pressure signal: time-domain, frequency-domain, and time-frequency-domain analysis, to extract knock-related amplitude features that reflect the degree of abnormal pressure oscillations during combustion.

[0052] In some embodiments, the adjustment step is performed by adjusting only the compression ratio of the engine while keeping the other operating conditions of the engine substantially unchanged.

[0053] For example, while keeping other operating conditions such as engine speed, load, ignition strategy, and fuel supply method basically unchanged, the engine compression ratio is adjusted by a predetermined amount to stimulate the difference in knock response of fuel under different combustion conditions.

[0054] The compression ratio of an engine can be changed by a compression ratio adjustment mechanism (not shown, which adjusts the distance between the engine cylinder head and the cylinder block). The compression ratio can be gradually increased through this mechanism, and tests can be conducted at different compression ratios to explore the knock response of the fuel.

[0055] Under different compression ratios, the knock-related amplitude characteristics are compared and analyzed to construct a descriptive quantity for the response behavior of the knock-related amplitude characteristics as a function of compression ratio. The descriptive quantity is expressed as the rate of change of the knock-related amplitude characteristics relative to the compression ratio, and is used to characterize the fuel's knock sensitivity to changes in compression ratio. In some embodiments, the descriptive quantity R can be expressed as: (1) Where A represents the knock-related amplitude characteristics, and CR represents the engine compression ratio.

[0056] In some embodiments, the blast resistance includes an octane number or a range of octane numbers.

[0057] In some embodiments, based on the descriptive quantity of the knock response behavior, a variety of knock-related features that characterize the abnormal combustion properties are constructed, including at least two of the following features: knock-related amplitude level, amplitude fluctuation degree, descriptive quantity of the response behavior of the knock-related amplitude feature as a function of compression ratio, and knock occurrence ratio.

[0058] In this disclosure, by further integrating multi-dimensional features such as detonation amplitude level, amplitude fluctuation characteristics, response change rate, and detonation occurrence ratio in the manner described above, a comprehensive detonation response index is constructed. This avoids the randomness and instability caused by relying solely on a single detonation amplitude or integral intensity for octane number determination. This multi-feature fusion is not a simple superposition, but rather uses detonation response behavior as the main thread to comprehensively characterize the fuel's anti-knock performance, thereby improving the model's robustness and generalization ability under different fuel types and operating conditions.

[0059] In addition to the analytical parameters related to knock characteristics mentioned above, parameters such as the frequency band energy and vibration decay time constant of knock can also be analyzed using the obtained cylinder pressure information. These parameters, as well as those mentioned above, are all based on the obtained in-cylinder pressure signal data.

[0060] Furthermore, those skilled in the art can select parameter combinations based on their advantages in different situations.

[0061] For example, choosing a combination of detonation-related amplitude level and amplitude fluctuation degree can provide a comprehensive description of the intensity and instability of detonation, which is suitable for analyzing the intensity of detonation.

[0062] For example, choosing a combination of amplitude fluctuation and knock occurrence ratio is more helpful in evaluating fuel performance at different compression ratios.

[0063] In some embodiments, during the fusion step, the comprehensive detonation response index is obtained by performing dimensionless processing on multiple detonation-related features and then using a weighted fusion method.

[0064] In this disclosure, the influence of differences in dimensions and numerical ranges between different features can be eliminated by performing dimensionless processing on various knock-related features.

[0065] The comprehensive knock response index I, constructed by weighted fusion of dimensionless knock-related characteristics, is expressed as follows: (2) in, The i-th type of detonation-related feature after normalization; The corresponding weight coefficients, and satisfying =1 (3).

[0066] The weighting coefficient in the weighted fusion is either a preset weighting coefficient or a weighting coefficient determined based on historical test data.

[0067] Based on the numerical distribution characteristics of the comprehensive knock response index, the knock sensitivity of fuel is classified and a fuel anti-knock performance criterion is constructed. The anti-knock performance criterion is mapped to a preset octane number correspondence, and the corresponding octane number or its numerical range is output.

[0068] This disclosure obtains in-cylinder combustion pressure signals under different compression ratio conditions by using a variable compression ratio structure in the engine and gradually increasing the engine compression ratio; extracts knock-related amplitude features from the in-cylinder combustion pressure signals and calculates the descriptive quantity of its response behavior as a function of compression ratio; based on this, it further constructs and fuses multiple knock-related features to obtain a comprehensive knock response index; and predicts the octane number or its numerical range corresponding to the fuel based on the classification results of the comprehensive knock response index.

[0069] By employing the above method, this disclosure achieves the following beneficial effects: by adjusting the compression ratio to induce fuel knock response behavior, it more realistically characterizes the fuel's anti-knock performance; by using a multi-feature fusion approach, it reduces the randomness and instability caused by a single knock feature; the knock-related amplitude feature is characterized by the maximum amplitude of knock pressure in the combustion cycle, but the maximum amplitude of knock pressure is only used as one input variable in the multi-feature fusion model, rather than as the sole or direct criterion for determining the fuel's anti-knock performance, thereby improving the stability and generalization ability of the octane number prediction results, avoiding direct prediction of octane number based on a single knock amplitude, and improving the stability of the prediction results; it is applicable to high-octane fuels and oxygenated additive fuel systems, and has strong engineering applicability.

[0070] Figure 2 This is a schematic block diagram of an octane number prediction device based on detonation pressure amplitude response behavior and multi-feature fusion according to an embodiment of this disclosure.

[0071] Secondly, referring to Figure 2 This disclosure provides an octane number prediction device 100 based on knock pressure amplitude response behavior and multi-feature fusion, which predicts the anti-knock performance of fuel using the above method. The octane number prediction device 100 includes an in-cylinder pressure sensor 110 and a data analysis system 120.

[0072] In some embodiments, the in-cylinder pressure sensor 110 and the data analysis system 120 are used to process the in-cylinder combustion pressure signal to extract knock-related amplitude features, construct knock response behavior descriptors, and predict the anti-knock performance of the fuel based on a multi-feature fusion method.

[0073] The octane number prediction device 100 disclosed herein executes the aforementioned octane number prediction method using an in-cylinder pressure sensor 110 and a data analysis system 120, realizing a fuel octane number prediction device based on knock pressure amplitude response behavior and multi-feature fusion. While keeping other engine operating conditions essentially unchanged, this device obtains the knock response characteristics of fuel under different compression ratios by adjusting the engine compression ratio, thereby more accurately assessing the anti-knock performance of fuel in actual engines.

[0074] In some embodiments, the octane number prediction device 100 disclosed herein may further include: an electronically controlled fuel injection system, which includes a pressure control switch 6 and a pressure gauge 4 disposed on the fuel line 5 and a fuel injector 7 connected to an electronic control unit (ECU) 13, so as to realize real-time monitoring and precise adjustment of fuel pressure.

[0075] Figure 3 This is a schematic structural diagram of an octane number prediction device 100 based on detonation pressure amplitude response behavior and multi-feature fusion according to an embodiment of the present disclosure.

[0076] The octane number prediction device 100 disclosed herein includes a high-pressure nitrogen cylinder 1, a high-pressure gas line 2, a fuel tank 3, a pressure gauge 4, a fuel line 5, a pressure control switch 6, a fuel injector 7, an intake manifold 8, an exhaust manifold 9, a cooling device 10, an intake heating jacket 11, a thermocouple 12, an electronic control unit (ECU) 13, an octane number tester 14, an igniter 15, an in-cylinder pressure sensor 16, a combustion analyzer 17, an oxygen sensor 18, a Lambda analyzer 19, and a data analysis system 20.

[0077] A high-pressure nitrogen cylinder 1 is connected to a fuel tank 3 via a high-pressure gas line 2, providing stable fuel pressure. Fuel is delivered to the fuel injector 7 via a pressure control switch 6, a pressure gauge 4, and a fuel line 5, enabling real-time monitoring and precise adjustment of fuel pressure. The fuel injector 7 is connected to an electronic control unit (ECU) 13 and a data analysis system 20 for precise control of the fuel injection process. The fuel injector 7 is positioned on the intake manifold 8, preferably upstream of the intake manifold 8, to ensure that the fuel is fully atomized and evenly mixed with air before entering the combustion chamber. An intake heating jacket 11 is installed outside the intake manifold 8, and a thermocouple 12 is installed inside the intake manifold 8 for monitoring and adjusting the intake air temperature. Both the intake manifold 8 and the thermocouple 12 are connected to the electronic control unit (ECU) 13 and the data analysis system 20 for coordinated control.

[0078] The octane rating tester 14 includes an engine combustion chamber 21, intake valves 22, and cylinder structure 23. An igniter 15 and an in-cylinder pressure sensor 16 are mounted on the cylinder head, respectively connected to an electronic control unit (ECU) 13 and a data analysis system 20, for ignition control and in-cylinder combustion pressure signal acquisition. An oxygen sensor 18 is mounted on the exhaust pipe 9, connected to a Lambda analyzer 19, the ECU 13, and the data analysis system 20, for measuring the post-combustion oxygen content and calculating the fuel equivalence ratio.

[0079] To ensure experimental accuracy, pressure gauge 4 and pressure control switch 6 can be configured as two or more, enabling multi-point monitoring and precise control of fuel pressure. A cooling device 10 is installed on the fuel injector 7 to reduce the impact of temperature fluctuations on injection characteristics, thereby ensuring the consistency of experimental results. The fuel injector 7, in-cylinder pressure sensor 16, Lambda analyzer 17, and igniter 15 are all controlled by an electronic control unit (ECU) 13, achieving coordinated adjustment of fuel injection, ignition timing, and stoichiometry.

[0080] In this disclosure, a high-pressure nitrogen cylinder 1 applies a stable pressure to the fuel tank 3, ensuring that the fuel is fully atomized and mixed with air in the intake manifold 8 before entering the combustion chamber. An in-cylinder pressure sensor 16 measures the in-cylinder combustion pressure signal in real time, and the combustion analyzer 17 and data analysis system 20 process this pressure signal to obtain knock pressure amplitude characteristics and other combustion parameters. The fuel equivalence ratio is measured by an oxygen sensor 18 and a Lambda analyzer 19 on the exhaust manifold 9, and is maintained stable by closed-loop control of the electronic control unit (ECU) 13.

[0081] In this disclosure, the octane rating tester 14 has electronic fuel injection functionality. The octane rating prediction device 100 of this disclosure also includes an input / output interface (not shown) for inputting fuel information and displaying octane rating prediction results.

[0082] The cylinder pressure sensor 16, electronic control unit (ECU) 13, combustion analyzer 17 and data analysis system 20 of the octane number prediction device 100 disclosed herein are used to control compression ratio, fuel injection and ignition, and process pressure signals to extract knock-related amplitude features and construct knock response behavior descriptors.

[0083] In some embodiments, the octane number prediction device 100 of this disclosure can be obtained by modifying a conventional octane number tester; the modification includes: replacing a conventional knock sensor with an in-cylinder pressure sensor 16; replacing the carburetor fuel supply system with an electronically controlled fuel injection system, the electronically controlled fuel injection system including a pressure control switch 6 and a pressure gauge 4 installed on the fuel line 5 and a fuel injector 7 connected to an electronic control unit (ECU) 13 to achieve real-time monitoring and precise adjustment of fuel pressure; optimizing the intake system structure, wherein the fuel injector 7 is arranged upstream of the intake pipe 8 to ensure that the fuel is fully atomized and uniformly mixed with air before entering the combustion chamber, and an intake heating jacket 11 is installed outside the intake pipe 8 for monitoring and adjusting the intake temperature; and installing an analysis device for measuring the fuel equivalence ratio in the exhaust system, installing an oxygen sensor 18 on the exhaust pipe 9, and connecting the oxygen sensor 18 to a Lambda analyzer 19, an electronic control unit (ECU) 13 and a data analysis system 20 for measuring the oxygen content after combustion and calculating the fuel equivalence ratio.

[0084] In some embodiments, the octane number prediction device 100 of this disclosure is applicable to fuels with an octane number higher than 100 and oxygenated additive fuels.

[0085] This disclosure uses the above-described apparatus and method to adjust the engine compression ratio while keeping other engine operating conditions basically unchanged, analyze the change law of fuel knock response under different compression ratio conditions, construct a fuel knock sensitivity criterion, and predict the fuel octane number based on the criterion.

[0086] Example embodiments have been disclosed herein, and while specific terminology has been used, it is for illustrative purposes only and should be construed as such, and is not intended to be limiting. In some instances, it will be apparent to those skilled in the art that features, characteristics, and / or elements described in connection with particular embodiments may be used alone, or in combination with features, characteristics, and / or elements described in connection with other embodiments, unless otherwise expressly indicated. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of this disclosure as set forth by the appended claims.

Claims

1. An octane number prediction method based on knock pressure amplitude response behavior and multi-feature fusion, characterized in that, The method includes the following steps: Extract knock-related amplitude characteristics that characterize the degree of abnormal high-frequency pressure oscillations during combustion; The engine compression ratio is adjusted step by step to stimulate the difference in knock response of fuel under different compression ratio conditions; Based on the aforementioned detonation response differences, a descriptive quantity for the response behavior of the detonation-related amplitude characteristics as a function of compression ratio is constructed. Based on the aforementioned response behavior descriptor, multiple detonation-related features are constructed, and these multiple detonation-related features are fused to obtain a comprehensive detonation response index. The anti-knock performance of fuel is predicted based on the comprehensive knock response index.

2. The octane prediction method of claim 1, wherein Detonation-related amplitude features, which characterize the degree of abnormal high-frequency pressure oscillations during combustion, are extracted, including: Under the condition that the engine is operating under preset stable conditions, in-cylinder combustion pressure signals of multiple combustion cycles are collected; The in-cylinder combustion pressure signal is analyzed to extract the knock-related amplitude characteristics that characterize the degree of abnormal high-frequency pressure oscillations during the combustion process.

3. The octane prediction method of claim 1, wherein The engine compression ratio is adjusted in stages, including: While keeping the other operating conditions of the engine basically unchanged, the compression ratio of the engine is adjusted.

4. The octane number prediction method according to claim 1, characterized in that, The response behavior descriptor is expressed as the rate of change of the knock-related amplitude feature relative to the change in compression ratio, used to characterize the knock sensitivity of fuel to changes in compression ratio. The response behavior descriptor R is expressed as: Where A represents the knock-related amplitude characteristics, and CR represents the engine compression ratio.

5. The octane number prediction method according to claim 1, characterized in that, The various knock-related features are high-frequency pressure oscillation amplitude features extracted from the in-cylinder combustion pressure signal.

6. The octane number prediction method according to claim 1, characterized in that, The various knock-related characteristics include the following features: At least two of these are: knock-related amplitude level, amplitude fluctuation degree, descriptive quantity of knock-related amplitude characteristics as a function of compression ratio, and knock occurrence rate.

7. The octane number prediction method according to claim 1, characterized in that, The comprehensive detonation response index is obtained by performing dimensionless processing on the various detonation-related features and then using a weighted fusion method. The comprehensive detonation response index is expressed as follows: in, The i-th type of detonation-related feature after normalization; The corresponding weight coefficients, and satisfying =1.

8. The octane number prediction method according to claim 7, characterized in that, The weighting coefficient in the weighted fusion is one of a preset weighting coefficient and a weighting coefficient determined based on historical test data.

9. An octane number prediction device based on detonation pressure amplitude response behavior and multi-feature fusion, which predicts the anti-knock performance of fuel using the octane number prediction method according to any one of claims 1 to 8, characterized in that, The octane number prediction device includes an in-cylinder pressure sensor and a data analysis system. The in-cylinder pressure sensor acquires combustion pressure signals in real time, and the data analysis system performs signal processing.

10. The octane number prediction device according to claim 9, characterized in that, The device also includes an electronically controlled fuel injection system, which includes a pressure control switch and a pressure gauge installed on the fuel line, as well as fuel injectors connected to the electronic control unit, to achieve real-time monitoring and precise adjustment of fuel pressure.

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