CN118188186A - A method for diagnosing and controlling knock state of a spark ignition engine - Google Patents

A method for diagnosing and controlling knock state of a spark ignition engine Download PDF

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CN118188186A
CN118188186A CN202410475787.0A CN202410475787A CN118188186A CN 118188186 A CN118188186 A CN 118188186A CN 202410475787 A CN202410475787 A CN 202410475787A CN 118188186 A CN118188186 A CN 118188186A
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knock
threshold
ignition timing
signal
step length
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尹晓军
任宪丰
段浩
曾科
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Xian Jiaotong University
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D35/00Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
    • F02D35/02Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
    • F02D35/027Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions using knock sensors
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02PIGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P5/00Advancing or retarding ignition; Control therefor
    • F02P5/04Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions
    • F02P5/145Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions using electrical means
    • F02P5/15Digital data processing
    • F02P5/152Digital data processing dependent on pinking

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Electrical Control Of Ignition Timing (AREA)

Abstract

本发明公开了一种点燃式发动机爆震状态诊断及分级控制的方法,1、采集点燃式发动机气缸压力信号并采用信号处理模块对燃烧状态进行分析;2、基于信号处理模块的分析结果,对燃烧状态进行判定,并对爆震强度进行定义;3、通过爆震传感器检测点燃式发动机的振动并产生相应的电压信号,通过对电压信号处理,得到相应的爆震特征频率,基于气缸压力信号,对爆震特征频率进行分级,得到相应的爆震阈值;4、建立爆震强度信号和爆震阈值的映射关系;5、建立各爆震阈值对应相应的点火时刻推后步长关系;6、判断当前爆震信号是否超过对应的爆震阈值,并将点火时刻推后相应步长。本发明方法解决了目前爆震传感器信号未分级、抑制爆震控制策略粗放等问题,同时提高点燃式发动机可靠性和经济性。

The present invention discloses a method for diagnosing and hierarchical control of knock state of a spark-ignition engine, comprising: 1. collecting cylinder pressure signals of the spark-ignition engine and using a signal processing module to analyze the combustion state; 2. judging the combustion state based on the analysis results of the signal processing module and defining the knock intensity; 3. detecting the vibration of the spark-ignition engine through a knock sensor and generating a corresponding voltage signal, obtaining the corresponding knock characteristic frequency by processing the voltage signal, and classifying the knock characteristic frequency based on the cylinder pressure signal to obtain the corresponding knock threshold; 4. establishing a mapping relationship between the knock intensity signal and the knock threshold; 5. establishing a relationship between the corresponding ignition time delay step length corresponding to each knock threshold; 6. judging whether the current knock signal exceeds the corresponding knock threshold, and delaying the ignition time by a corresponding step length. The method of the present invention solves the problems of the current knock sensor signal not being classified and the knock suppression control strategy being rough, and at the same time improves the reliability and economy of the spark-ignition engine.

Description

一种点燃式发动机爆震状态诊断及分级控制的方法A method for diagnosing and controlling knock state of a spark ignition engine

技术领域Technical Field

本发明点燃式发动机爆震抑制技术领域,具体涉及一种点燃式发动机爆震状态诊断及分级控制的方法。The present invention relates to the technical field of spark ignition engine knock suppression, and in particular to a method for diagnosing and hierarchical control of knock states of a spark ignition engine.

背景技术Background technique

爆震现象是发动机缸内终燃混合气的快速自燃现象。在轻微爆震时,发动机功率略有增加;强烈爆震时,发动机功率下降,工作变得不稳定,转速下降,发动机有较大振动。爆震是限制点燃式发动机功率提升和经济性改善的一个重要因素。Knock is the rapid self-ignition of the final combustion mixture in the engine cylinder. In the case of slight knock, the engine power increases slightly; in the case of strong knock, the engine power decreases, the operation becomes unstable, the speed decreases, and the engine vibrates greatly. Knock is an important factor that limits the improvement of the power and economy of the spark ignition engine.

爆震分为两种,一种是普通爆震,一种是超级爆震。普通爆震往往发生在火花塞点火时刻后,而超级爆震发生在火花塞点火时刻之前。目前采用爆震传感器来检测爆震状态,通常采用推迟点火时刻的方法来抑制爆震。现有爆震传感器的信号处理并未对不同强度的爆震信号进行界定。此外,爆震抑制方面,在检测到爆震发生时,采用固定的点火时刻推迟角,虽在一定程度上,可以抑制爆震的发生,但是对发动机的燃油经济性有较大牺牲。There are two types of knock, one is ordinary knock and the other is super knock. Ordinary knock often occurs after the spark plug ignites, while super knock occurs before the spark plug ignites. At present, knock sensors are used to detect the knock state, and the method of delaying the ignition timing is usually used to suppress the knock. The signal processing of existing knock sensors does not define knock signals of different intensities. In addition, in terms of knock suppression, when knock is detected, a fixed ignition timing delay angle is used. Although it can suppress the occurrence of knock to a certain extent, it has a great sacrifice on the fuel economy of the engine.

因此,如何对检测的爆震信号进行区分,并且基于不同强度的爆震水平采取相应的爆震抑制措施,是当前亟需解决的难题。Therefore, how to distinguish the detected knock signals and take corresponding knock suppression measures based on knock levels of different intensities is a difficult problem that needs to be solved urgently.

发明内容Summary of the invention

为了克服上述现有技术存在的问题,本发明的目的在于提出一种点燃式发动机爆震状态诊断及分级控制的方法,旨在解决目前爆震传感器信号未分级、抑制爆震控制策略粗放等问题,同时提高点燃式发动机可靠性和经济性。In order to overcome the problems existing in the above-mentioned prior art, the purpose of the present invention is to propose a method for diagnosing and hierarchical control of the knock state of a spark-ignition engine, aiming to solve the current problems of ungraded knock sensor signals and rough knock suppression control strategies, while improving the reliability and economy of the spark-ignition engine.

为了达到上述目的,本发明采用如下技术方案:In order to achieve the above object, the present invention adopts the following technical solution:

一种点燃式发动机爆震状态诊断及分级控制的方法,包括如下步骤:A method for diagnosing and hierarchically controlling knock state of a spark-ignition engine comprises the following steps:

步骤1:通过缸压传感器采集点燃式发动机气缸压力信号并采用信号处理模块对燃烧状态进行分析;Step 1: Collect the cylinder pressure signal of the spark ignition engine through the cylinder pressure sensor and analyze the combustion state using the signal processing module;

步骤2:基于信号处理模块的分析结果,定义爆震强度为爆震计算窗口内信号的平方积分结果用于表征爆震等级,其计算公式如下:Step 2: Based on the analysis results of the signal processing module, the knock intensity is defined as the square integral result of the signal within the knock calculation window to characterize the knock level. The calculation formula is as follows:

式中:N为爆震计算窗口的数据点数量;Where: N is the number of data points in the knock calculation window;

x(i)为信号处理后的压力数据;x(i) is the pressure data after signal processing;

基于爆震强度数据对爆震强度进行定义,分别定义为轻度爆震、中度爆震和重度爆震;The knock intensity is defined based on the knock intensity data, which are defined as mild knock, moderate knock and severe knock;

步骤3:爆震传感器检测点燃式发动机的振动并产生相应的电压信号,通过对电压信号进行低通滤波以及带通滤波信号处理,得到相应的爆震特征频率,基于缸压传感器的气缸压力信号,对爆震特征频率进行分级,得到相应的爆震阈值,分别为爆震阈值A、爆震阈值B和爆震阈值C;爆震阈值的数值关系为:爆震阈值A<爆震阈值B<爆震阈值C;Step 3: The knock sensor detects the vibration of the spark-ignition engine and generates a corresponding voltage signal. The corresponding knock characteristic frequency is obtained by low-pass filtering and band-pass filtering the voltage signal. The knock characteristic frequency is classified based on the cylinder pressure signal of the cylinder pressure sensor to obtain the corresponding knock thresholds, which are knock threshold A, knock threshold B and knock threshold C. The numerical relationship of the knock thresholds is: knock threshold A < knock threshold B < knock threshold C;

步骤4:将信号处理模块处理后的气缸压力信号与爆震传感器的处理信号进行离线对比分析,建立爆震强度信号和爆震阈值的映射关系:轻度爆震对应爆震阈值A,中度爆震对应爆震阈值B,重度爆震对应爆震阈值C;Step 4: Perform offline comparative analysis on the cylinder pressure signal processed by the signal processing module and the processing signal of the knock sensor, and establish a mapping relationship between the knock intensity signal and the knock threshold: mild knock corresponds to knock threshold A, moderate knock corresponds to knock threshold B, and severe knock corresponds to knock threshold C;

步骤5:基于爆震特征频率分级的结果,各爆震阈值分别对应相应的点火时刻推后步长:爆震阈值A对应点火时刻推后步长A,爆震阈值B对应点火时刻推后步长B,爆震阈值C对应点火时刻推后步长C;点火时刻推后步长的数值关系为:点火时刻推后步长A<点火时刻推后步长B<点火时刻推后步长C;Step 5: Based on the result of knock characteristic frequency classification, each knock threshold corresponds to a corresponding ignition timing delay step length: knock threshold A corresponds to ignition timing delay step length A, knock threshold B corresponds to ignition timing delay step length B, and knock threshold C corresponds to ignition timing delay step length C; the numerical relationship of the ignition timing delay step length is: ignition timing delay step length A < ignition timing delay step length B < ignition timing delay step length C;

步骤6:判断当前爆震信号是否超过爆震阈值C,若是,则判定此时缸内燃烧处于重度爆震状态,立刻推迟点火时刻,点火时刻推后步长C;更新点火时刻后,重新判定当前爆震信号是否超过爆震阈值C,若否,则进入下一个判定过程;Step 6: Determine whether the current knock signal exceeds the knock threshold C. If so, determine that the combustion in the cylinder is in a severe knock state at this time, and immediately postpone the ignition timing by a step length of C; after updating the ignition timing, re-determine whether the current knock signal exceeds the knock threshold C. If not, enter the next determination process;

步骤7:判定当然爆震信号是否超过爆震阈值B,若是,则判定此时缸内燃烧处于中度爆震状态,立刻推迟点火时刻,点火时刻推后步长B;更新点火时刻后,重新判定当前爆震信号是否超过爆震阈值C和爆震阈值B,若否,则进入下一个判定过程;Step 7: Determine whether the knock signal exceeds the knock threshold value B. If so, determine that the combustion in the cylinder is in a moderate knock state at this time, and immediately postpone the ignition timing by a step length B; after updating the ignition timing, re-determine whether the current knock signal exceeds the knock threshold value C and the knock threshold value B. If not, enter the next determination process;

步骤8:判定当前爆震信号是否超过爆震阈值A,若是,则判定此时缸内燃烧处于轻度爆震状态,此时无需立刻推迟点火时刻,待发动机运行预设时间后,点火时刻推后步长A;更新点火时刻后,重新判定当前爆震信号是否超过爆震阈值C、爆震阈值B和爆震阈值A,若否,则判定此时未发生爆震。Step 8: Determine whether the current knock signal exceeds the knock threshold A. If so, it is determined that the combustion in the cylinder is in a mild knock state at this time. There is no need to immediately postpone the ignition timing. After the engine runs for a preset time, the ignition timing is postponed by a step length A. After updating the ignition timing, re-determine whether the current knock signal exceeds the knock threshold C, knock threshold B and knock threshold A. If not, it is determined that no knock occurs at this time.

优选的,步骤1中,信号处理模块采用提升小波变换方法和经验模态分解方法对燃烧状态进行分析;小波变换方法在故障诊断中具有时间分辨率和频率分辨率随频率变化自适应的特点,通过对气缸压力信号进行小波变换,计算出小波变换在不同尺度上的小波能量作为诊断特征量,从而得到燃烧状态的特征参数。如果是异常燃烧状态,则需要基于小波能量对爆震强度进行定义,分别定义为轻度爆震、中度爆震和重度爆震。Preferably, in step 1, the signal processing module uses the lifting wavelet transform method and the empirical mode decomposition method to analyze the combustion state; the wavelet transform method has the characteristics of adaptive time resolution and frequency resolution with frequency changes in fault diagnosis, and the wavelet energy of the wavelet transform at different scales is calculated as the diagnostic feature quantity by performing wavelet transform on the cylinder pressure signal, thereby obtaining the characteristic parameters of the combustion state. If it is an abnormal combustion state, the knock intensity needs to be defined based on the wavelet energy, and is defined as mild knock, moderate knock and severe knock respectively.

优选的,步骤6中,若判定此时未发生爆震,为了进一步提升发动机的经济性,则选择更为提前的点火时刻,点火时刻提前0.5°CA;然后重新对此时燃烧状态进行判定,。Preferably, in step 6, if it is determined that no knock occurs at this time, in order to further improve the economy of the engine, a more advanced ignition timing is selected, and the ignition timing is advanced by 0.5°CA; then the combustion state at this time is re-determined.

和现有技术相比较,本发明具备如下优点:Compared with the prior art, the present invention has the following advantages:

1、由于目前爆震传感器检测信号存在误报或误检测的情况,本发明通过爆震状态诊断及分级,提高了发动机爆震检测和分析的准确性,使得发动机能够快速、准确的进行爆震控制反馈,降低了发动机运行的爆震风险,保护发动机安全运行;1. Since there are cases of false alarms or false detections in the current knock sensor detection signals, the present invention improves the accuracy of engine knock detection and analysis through knock state diagnosis and classification, so that the engine can quickly and accurately perform knock control feedback, reduce the knock risk of the engine operation, and protect the safe operation of the engine;

2、本发明采用爆震分级控制策略,可减小爆震对发动机运行的不利影响,并有效提高发动机的动力性和经济性。2. The present invention adopts a knock graded control strategy, which can reduce the adverse effects of knock on engine operation and effectively improve the power and economy of the engine.

附图说明BRIEF DESCRIPTION OF THE DRAWINGS

图1为点燃式发动机爆震信号识别和级别区分即爆震状态诊断的流程示意图。FIG. 1 is a flow chart of knock signal recognition and level differentiation of a spark-ignition engine, i.e., knock state diagnosis.

图2为点燃式发动机爆震分级控制的流程示意图。FIG. 2 is a flow chart of the knock staged control of a spark ignition engine.

具体实施方式Detailed ways

下面结合附图和具体实施方式对本发明作进一步详细说明。The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

如图1所示,点燃式发动机爆震信号识别和级别区分即爆震状态诊断方法如下:As shown in FIG1 , the knock signal recognition and level distinction of the spark-ignition engine, i.e., the knock state diagnosis method, is as follows:

通过缸压传感器采集点燃式发动机气缸压力信号,气缸压力信号进入信号处理模块。在信号处理模块中,采用提升小波变换和经验模态分解两种方法对燃烧状态进行分析,以便为爆震信号的诊断提供依据。小波变换方法在故障诊断中具有时间分辨率和频率分辨率随频率变化自适应的特点,通过对气缸压力信号进行小波变换,可以计算出小波变换在不同尺度上的小波能量作为诊断特征量,从而得到燃烧状态的特征参数,实现对发动机爆震燃烧的故障诊断。基于信号处理模块的分析结果,对燃烧状态进行判定。如果是异常燃烧状态,则需要基于小波能量对爆震强度进行定义,分别定义为轻度爆震、中度爆震和重度爆震。The cylinder pressure signal of the spark-ignition engine is collected by the cylinder pressure sensor, and the cylinder pressure signal enters the signal processing module. In the signal processing module, the combustion state is analyzed by using the lifting wavelet transform and empirical mode decomposition methods to provide a basis for the diagnosis of the knock signal. The wavelet transform method has the characteristics of adaptive time resolution and frequency resolution with frequency changes in fault diagnosis. By performing wavelet transform on the cylinder pressure signal, the wavelet energy of the wavelet transform at different scales can be calculated as the diagnostic feature quantity, thereby obtaining the characteristic parameters of the combustion state and realizing the fault diagnosis of engine knock combustion. Based on the analysis results of the signal processing module, the combustion state is determined. If it is an abnormal combustion state, the knock intensity needs to be defined based on the wavelet energy, which is defined as mild knock, moderate knock and severe knock respectively.

目前,爆震传感器已普遍装配到点燃式发动机上,通过检测点燃式发动机的振动,爆震传感器会产生相应的电压信号,通过对信号进行低通滤波以及带通滤波信号处理,可以得到相应的爆震特征频率。基于缸压传感器的气缸压力信号,对爆震特征频率进行分区,得到相应的爆震阈值,分别为爆震阈值A、爆震阈值B和爆震阈值C,爆震阈值的数值关系为:爆震阈值A<爆震阈值B<爆震阈值C。本实施例中,以排量为13L的点燃式发动机为例,通过试验标定,爆震阈值A为0.50,爆震阈值B为0.75,爆震阈值C为0.85。At present, knock sensors have been generally installed on spark-ignition engines. By detecting the vibration of the spark-ignition engine, the knock sensor will generate a corresponding voltage signal. By performing low-pass filtering and band-pass filtering signal processing on the signal, the corresponding knock characteristic frequency can be obtained. Based on the cylinder pressure signal of the cylinder pressure sensor, the knock characteristic frequency is partitioned to obtain the corresponding knock thresholds, which are knock threshold A, knock threshold B and knock threshold C. The numerical relationship of the knock thresholds is: knock threshold A < knock threshold B < knock threshold C. In this embodiment, taking a spark-ignition engine with a displacement of 13L as an example, through experimental calibration, the knock threshold A is 0.50, the knock threshold B is 0.75, and the knock threshold C is 0.85.

将信号处理模块处理后的气缸压力信号与爆震传感器的处理信号进行离线对比分析,建立爆震强度信号和爆震阈值的映射关系。The cylinder pressure signal processed by the signal processing module is compared and analyzed offline with the processing signal of the knock sensor to establish a mapping relationship between the knock intensity signal and the knock threshold.

轻度爆震对应爆震阈值A,中度爆震对应爆震阈值B,重度爆震对应爆震阈值C。Mild knock corresponds to knock threshold A, moderate knock corresponds to knock threshold B, and severe knock corresponds to knock threshold C.

基于爆震特征频率分级的结果,各爆震阈值分别对应相应的点火时刻推后步长。爆震阈值A对应点火时刻推后步长A,爆震阈值B对应点火时刻推后步长B,爆震阈值C对应点火时刻推后步长C。Based on the result of knock characteristic frequency classification, each knock threshold corresponds to a corresponding ignition timing delay step length. Knock threshold A corresponds to ignition timing delay step length A, knock threshold B corresponds to ignition timing delay step length B, and knock threshold C corresponds to ignition timing delay step length C.

点火时刻推后步长的数值关系为:点火时刻推后步长A<点火时刻推后步长B<点火时刻推后步长C。The numerical relationship of the ignition timing delay step length is: ignition timing delay step length A < ignition timing delay step length B < ignition timing delay step length C.

本实施例中,点火时刻推后步长A为0.2°CA,点火时刻推后步长B为0.6°CA,点火时刻推后步长C为1.0°CA。其中°CA表示曲轴转角。In this embodiment, the ignition timing delay step length A is 0.2°CA, the ignition timing delay step length B is 0.6°CA, and the ignition timing delay step length C is 1.0°CA, wherein °CA represents the crankshaft angle.

如图2所示,点燃式发动机爆震分级控制方法如下:As shown in Figure 2, the spark ignition engine knock staged control method is as follows:

在点燃式发动机运行时,首先获取当前点燃式发动机的运行工况、点火时刻和爆震传感器信号。When the spark-ignition engine is running, firstly, the current operating condition of the spark-ignition engine, the ignition timing and the knock sensor signal are obtained.

1、判断当前爆震信号是否超过爆震阈值C。1. Determine whether the current knock signal exceeds the knock threshold C.

若是,则判定此时缸内燃烧处于重度爆震状态,立刻推迟点火时刻,点火时刻推后步长C。更新点火时刻后,重新判定当前爆震信号是否超过爆震阈值C。If yes, it is determined that the combustion in the cylinder is in a severe knock state at this time, and the ignition timing is immediately postponed by a step length of C. After the ignition timing is updated, it is re-determined whether the current knock signal exceeds the knock threshold C.

若否,则进入下一个判定过程。If not, enter the next judgment process.

2、判定当然爆震信号是否超过爆震阈值B。2. Determine whether the knock signal exceeds the knock threshold B.

若是,则判定此时缸内燃烧处于中度爆震状态,立刻推迟点火时刻,点火时刻推后步长B。更新点火时刻后,重新判定当前爆震信号是否超过爆震阈值C、爆震阈值B。If so, it is determined that the combustion in the cylinder is in a moderate knock state at this time, and the ignition timing is immediately postponed by a step length B. After the ignition timing is updated, it is re-determined whether the current knock signal exceeds the knock threshold C and the knock threshold B.

若否,则进入下一个判定过程。If not, enter the next judgment process.

3、判定当前爆震信号是否超过爆震阈值A。3. Determine whether the current knock signal exceeds the knock threshold A.

若是,则判定此时缸内燃烧处于轻度爆震状态。由于轻度爆震有利于点燃式发动机经济性的提升。因此,此时无需立刻推迟点火时刻,待发动机运行一段时间(5分钟)后,推迟点火时刻,点火时刻推后步长A。更新点火时刻后,重新判定当前爆震信号是否超过爆震阈值C、爆震阈值B和爆震阈值A。If yes, it is determined that the combustion in the cylinder is in a mild knock state at this time. Since mild knock is conducive to improving the economy of the spark ignition engine, there is no need to postpone the ignition timing immediately. After the engine runs for a period of time (5 minutes), the ignition timing is postponed by a step length A. After the ignition timing is updated, it is re-determined whether the current knock signal exceeds the knock threshold C, knock threshold B and knock threshold A.

若否,则判定此时未发生爆震。为了进一步提升发动机的经济性,可选择更为提前的点火时刻,点火时刻提前0.5CA。然后重新对此时燃烧状态进行判定。If not, it is determined that no knock occurs at this time. In order to further improve the economy of the engine, a more advanced ignition timing can be selected, the ignition timing is advanced by 0.5CA. Then the combustion state at this time is re-determined.

在爆震状态分级控制时,点火时刻调整遵循的原则是快退慢进。即如果此时未重度爆震,则快速调节点火时刻。随着爆震强度的减弱,点火时刻推后的步长减小。当未出现爆震时,则缓慢提前点火时刻,提高了燃料燃烧效率和做功能力,进而提升发动机的经济性。When the knock state is controlled in stages, the principle followed by the ignition timing adjustment is fast retreat and slow advance. That is, if there is no severe knock at this time, the ignition timing is adjusted quickly. As the knock intensity decreases, the step length of the ignition timing is reduced. When there is no knock, the ignition timing is slowly advanced, which improves the fuel combustion efficiency and work capacity, thereby improving the economy of the engine.

Claims (4)

1.一种点燃式发动机爆震状态诊断及分级控制的方法,其特征在于:包括如下步骤:1. A method for diagnosing and hierarchical control of knock state of a spark ignition engine, characterized in that it comprises the following steps: 步骤1:通过缸压传感器采集点燃式发动机气缸压力信号并采用信号处理模块对燃烧状态进行分析;Step 1: Collect the cylinder pressure signal of the spark ignition engine through the cylinder pressure sensor and analyze the combustion state using the signal processing module; 步骤2:基于信号处理模块的分析结果,定义爆震强度为爆震计算窗口内信号的平方积分结果用于表征爆震等级,其计算公式如下:Step 2: Based on the analysis results of the signal processing module, the knock intensity is defined as the square integral result of the signal within the knock calculation window to characterize the knock level. The calculation formula is as follows: 式中:N为爆震计算窗口的数据点数量;Where: N is the number of data points in the knock calculation window; x(i)为信号处理后的压力数据;x(i) is the pressure data after signal processing; 基于爆震强度数据对爆震强度进行定义,分别定义为轻度爆震、中度爆震和重度爆震;The knock intensity is defined based on the knock intensity data, which are defined as mild knock, moderate knock and severe knock; 步骤3:爆震传感器检测点燃式发动机的振动并产生相应的电压信号,通过对电压信号进行低通滤波以及带通滤波信号处理,得到相应的爆震特征频率,基于缸压传感器的气缸压力信号,对爆震特征频率进行分级,得到相应的爆震阈值,分别为爆震阈值A、爆震阈值B和爆震阈值C;爆震阈值的数值关系为:爆震阈值A<爆震阈值B<爆震阈值C;Step 3: The knock sensor detects the vibration of the spark-ignition engine and generates a corresponding voltage signal. The corresponding knock characteristic frequency is obtained by low-pass filtering and band-pass filtering the voltage signal. The knock characteristic frequency is classified based on the cylinder pressure signal of the cylinder pressure sensor to obtain the corresponding knock thresholds, which are knock threshold A, knock threshold B and knock threshold C. The numerical relationship of the knock thresholds is: knock threshold A < knock threshold B < knock threshold C; 步骤4:将信号处理模块处理后的气缸压力信号与爆震传感器的处理信号进行离线对比分析,建立爆震强度信号和爆震阈值的映射关系:轻度爆震对应爆震阈值A,中度爆震对应爆震阈值B,重度爆震对应爆震阈值C;Step 4: Perform offline comparative analysis on the cylinder pressure signal processed by the signal processing module and the processing signal of the knock sensor, and establish a mapping relationship between the knock intensity signal and the knock threshold: mild knock corresponds to knock threshold A, moderate knock corresponds to knock threshold B, and severe knock corresponds to knock threshold C; 步骤5:基于爆震特征频率分级的结果,各爆震阈值分别对应相应的点火时刻推后步长:爆震阈值A对应点火时刻推后步长A,爆震阈值B对应点火时刻推后步长B,爆震阈值C对应点火时刻推后步长C;点火时刻推后步长的数值关系为:点火时刻推后步长A<点火时刻推后步长B<点火时刻推后步长C;Step 5: Based on the result of knock characteristic frequency classification, each knock threshold corresponds to a corresponding ignition timing delay step length: knock threshold A corresponds to ignition timing delay step length A, knock threshold B corresponds to ignition timing delay step length B, and knock threshold C corresponds to ignition timing delay step length C; the numerical relationship of the ignition timing delay step length is: ignition timing delay step length A < ignition timing delay step length B < ignition timing delay step length C; 步骤6:判断当前爆震信号是否超过爆震阈值C,若是,则判定此时缸内燃烧处于重度爆震状态,立刻推迟点火时刻,点火时刻推后步长C;更新点火时刻后,重新判定当前爆震信号是否超过爆震阈值C,若否,则进入下一个判定过程;Step 6: Determine whether the current knock signal exceeds the knock threshold C. If so, determine that the combustion in the cylinder is in a severe knock state at this time, and immediately postpone the ignition timing by a step length of C; after updating the ignition timing, re-determine whether the current knock signal exceeds the knock threshold C. If not, enter the next determination process; 步骤7:判定当然爆震信号是否超过爆震阈值B,若是,则判定此时缸内燃烧处于中度爆震状态,立刻推迟点火时刻,点火时刻推后步长B;更新点火时刻后,重新判定当前爆震信号是否超过爆震阈值C和爆震阈值B,若否,则进入下一个判定过程;Step 7: Determine whether the knock signal exceeds the knock threshold value B. If so, determine that the combustion in the cylinder is in a moderate knock state at this time, and immediately postpone the ignition timing by a step length B; after updating the ignition timing, re-determine whether the current knock signal exceeds the knock threshold value C and the knock threshold value B. If not, enter the next determination process; 步骤8:判定当前爆震信号是否超过爆震阈值A,若是,则判定此时缸内燃烧处于轻度爆震状态,此时无需立刻推迟点火时刻,待发动机运行预设时间后,点火时刻推后步长A;更新点火时刻后,重新判定当前爆震信号是否超过爆震阈值C、爆震阈值B和爆震阈值A,若否,则判定此时未发生爆震。Step 8: Determine whether the current knock signal exceeds the knock threshold A. If so, it is determined that the combustion in the cylinder is in a mild knock state at this time. There is no need to immediately postpone the ignition timing. After the engine runs for a preset time, the ignition timing is postponed by a step length A. After updating the ignition timing, re-determine whether the current knock signal exceeds the knock threshold C, knock threshold B and knock threshold A. If not, it is determined that no knock occurs at this time. 2.根据权利要求1所述的一种点燃式发动机爆震状态诊断及分级控制的方法,其特征在于:步骤1中,信号处理模块采用提升小波变换方法和经验模态分解方法对燃烧状态进行分析;小波变换方法在故障诊断中具有时间分辨率和频率分辨率随频率变化自适应的特点,通过对气缸压力信号进行小波变换,计算出小波变换在不同尺度上的小波能量作为诊断特征量,从而得到燃烧状态的特征参数。2. The method for diagnosing and hierarchical controlling the knock state of an ignition engine according to claim 1 is characterized in that: in step 1, the signal processing module uses a lifting wavelet transform method and an empirical mode decomposition method to analyze the combustion state; the wavelet transform method has the characteristics of adaptive time resolution and frequency resolution with frequency changes in fault diagnosis, and by performing wavelet transform on the cylinder pressure signal, the wavelet energy of the wavelet transform at different scales is calculated as a diagnostic feature quantity, thereby obtaining the characteristic parameters of the combustion state. 3.根据权利要求2所述的一种点燃式发动机爆震状态诊断及分级控制的方法,其特征在于:如果是异常燃烧状态,则需要基于小波能量对爆震强度进行定义,分别定义为轻度爆震、中度爆震和重度爆震。3. A method for diagnosing and hierarchical control of knock state of a spark ignition engine according to claim 2, characterized in that: if it is an abnormal combustion state, it is necessary to define the knock intensity based on wavelet energy, and define it as mild knock, moderate knock and severe knock respectively. 4.根据权利要求1所述的一种点燃式发动机爆震状态诊断及分级控制的方法,其特征在于:步骤6中,若判定此时未发生爆震,则选择更为提前的点火时刻,点火时刻提前0.5°CA;然后重新对此时燃烧状态进行判定,其中°CA表示曲轴转角。4. The method for diagnosing and hierarchically controlling knock state of a spark ignition engine according to claim 1, characterized in that: in step 6, if it is determined that knock does not occur at this time, a more advanced ignition timing is selected, and the ignition timing is advanced by 0.5°CA; then the combustion state at this time is re-determined, where °CA represents the crankshaft angle.
CN202410475787.0A 2024-04-19 2024-04-19 A method for diagnosing and controlling knock state of a spark ignition engine Pending CN118188186A (en)

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