CN118188186A - Method for diagnosing and grading control of knocking state of ignition engine - Google Patents
Method for diagnosing and grading control of knocking state of ignition engine Download PDFInfo
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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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- 238000002485 combustion reaction Methods 0.000 claims abstract description 29
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- 238000003745 diagnosis Methods 0.000 claims description 10
- 230000000979 retarding effect Effects 0.000 claims description 8
- 230000009466 transformation Effects 0.000 claims description 7
- 238000004364 calculation method Methods 0.000 claims description 6
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- 238000011426 transformation method Methods 0.000 claims description 5
- 230000002159 abnormal effect Effects 0.000 claims description 3
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- 238000000354 decomposition reaction Methods 0.000 claims description 3
- 238000011217 control strategy Methods 0.000 abstract description 3
- 238000001514 detection method Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
- F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
- F02D35/027—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions using knock sensors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
- F02P5/00—Advancing or retarding ignition; Control therefor
- F02P5/04—Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions
- F02P5/145—Advancing 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
- F02P5/15—Digital data processing
- F02P5/152—Digital 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
The invention discloses a method for diagnosing and grading the knocking state of an ignition engine, which comprises the steps of 1, collecting pressure signals of a cylinder of the ignition engine and analyzing the combustion state by adopting a signal processing module; 2. based on the analysis result of the signal processing module, judging the combustion state and defining the knock intensity; 3. detecting vibration of the ignition engine through a knock sensor and generating a corresponding voltage signal, obtaining a corresponding knock characteristic frequency through processing the voltage signal, and grading the knock characteristic frequency based on a cylinder pressure signal to obtain a corresponding knock threshold; 4. establishing a mapping relation between knock intensity signals and knock threshold values; 5. establishing a corresponding ignition time pushing and backing step relation of each knock threshold; 6. judging whether the current knock signal exceeds the corresponding knock threshold value or not, and pushing the ignition time by a corresponding step length. The method solves the problems that the signals of the knock sensor are not classified, the rough knock control strategy is restrained, and the like at present, and simultaneously improves the reliability and the economy of the ignition engine.
Description
Technical Field
The invention belongs to the technical field of knock suppression of ignition engines, and particularly relates to a method for diagnosing and grading control of a knock state of an ignition engine.
Background
Knocking phenomenon is a rapid auto-ignition phenomenon of the final combustion mixture in the cylinder of the engine. At the time of slight knocking, the engine power slightly increases; when the engine knocks strongly, the power of the engine is reduced, the operation becomes unstable, the rotation speed is reduced, and the engine vibrates greatly. Knock is an important factor limiting spark ignition engine power boost and economy improvement.
Knocking is classified into two types, one is ordinary knocking and one is super knocking. The normal knocking tends to occur after the ignition timing of the spark plug, while the super knocking occurs before the ignition timing of the spark plug. Knock sensors are currently used to detect knock conditions, and methods of retarding the timing of ignition are generally used to suppress knock. The signal processing of existing knock sensors does not define knock signals of different intensities. In addition, in terms of knock suppression, when knocking is detected, the occurrence of knocking can be suppressed to some extent by adopting a fixed ignition timing retardation angle, but there is a great sacrifice in fuel economy of the engine.
Therefore, how to distinguish the detected knock signals and to take corresponding knock suppressing measures based on knock levels of different intensities is a current challenge to be solved.
Disclosure of Invention
In order to overcome the problems of the prior art, the invention aims to provide a method for diagnosing and controlling the knocking state of an ignition engine in a grading manner, and aims to solve the problems that the signals of a knocking sensor are not graded, a knocking control strategy is inhibited from being rough and the like at present, and meanwhile, the reliability and the economy of the ignition engine are improved.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a method for diagnosing and controlling knock state of an ignition engine in a staged manner, comprising the steps of:
Step 1: acquiring a pressure signal of a cylinder of the ignition engine through a cylinder pressure sensor and analyzing a combustion state by adopting a signal processing module;
Step 2: based on the analysis result of the signal processing module, defining the knock intensity as the square integral result of the signal in the knock calculation window for representing the knock level, wherein the calculation formula is as follows:
Wherein: n is the number of data points of the knock calculation window;
x (i) is pressure data after signal processing;
Defining knock intensity based on knock intensity data, which is respectively defined as light knock, medium knock and heavy knock;
step 3: the method comprises the steps that a knock sensor detects vibration of an ignition engine and generates corresponding voltage signals, corresponding knock characteristic frequencies are obtained through low-pass filtering and band-pass filtering signal processing of the voltage signals, and the knock characteristic frequencies are classified based on cylinder pressure signals of a cylinder pressure sensor to obtain corresponding knock thresholds, namely a knock threshold A, a knock threshold B and a knock threshold C; the numerical relationship of the knock threshold is: knock threshold a < knock threshold B < knock threshold C;
Step 4: performing off-line comparison analysis on the cylinder pressure signal processed by the signal processing module and the processed signal of the knock sensor, and establishing a mapping relation between the knock intensity signal and the knock threshold value: mild knock corresponds to knock threshold a, moderate knock corresponds to knock threshold B, and severe knock corresponds to knock threshold C;
Step 5: based on the result of the knock characteristic frequency classification, each knock threshold corresponds to a corresponding ignition timing post step size: the knocking threshold A corresponds to the ignition moment backward step length A, the knocking threshold B corresponds to the ignition moment backward step length B, and the knocking threshold C corresponds to the ignition moment backward step length C; the numerical relation of the ignition time push-back step length is as follows: the ignition time back step length A is smaller than the ignition time back step length B is smaller than the ignition time back step length C;
Step 6: judging whether the current knocking signal exceeds a knocking threshold C, if so, judging that the in-cylinder combustion is in a heavy knocking state at the moment, and immediately retarding the ignition moment by a step length C after the ignition moment; after the ignition time is updated, whether the current knocking signal exceeds a knocking threshold C or not is judged again, and if not, the next judging process is carried out;
Step 7: judging whether the knocking signal exceeds a knocking threshold B or not, if so, judging that the in-cylinder combustion is in a medium knocking state at the moment, and immediately retarding the ignition moment, wherein the ignition moment is pushed back by a step length B; after the ignition time is updated, whether the current knock signal exceeds a knock threshold C and a knock threshold B is judged again, and if not, the next judging process is carried out;
Step 8: judging whether the current knocking signal exceeds a knocking threshold A, if so, judging that the in-cylinder combustion is in a mild knocking state, and immediately retarding the ignition moment, wherein after the engine runs for a preset time, the ignition moment is pushed by a step length A; after the ignition time is updated, whether the current knock signal exceeds a knock threshold C, a knock threshold B and a knock threshold A is judged again, and if not, knocking does not occur at the moment.
Preferably, in step 1, the signal processing module analyzes the combustion state by adopting a lifting wavelet transformation method and an empirical mode decomposition method; the wavelet transformation method has the characteristic that the time resolution and the frequency resolution are self-adaptive along with the frequency change in fault diagnosis, and wavelet energy of wavelet transformation on different scales is calculated as diagnosis characteristic quantity by carrying out wavelet transformation on cylinder pressure signals, so that the characteristic parameter of the combustion state is obtained. In the case of abnormal combustion conditions, it is necessary to define the knock intensity based on the wavelet energy, which is defined as mild knock, moderate knock, and severe knock, respectively.
Preferably, in step 6, if it is determined that knocking does not occur at this time, in order to further improve the economy of the engine, a more advanced ignition timing is selected, the ignition timing being advanced by 0.5 ° CA; then, the combustion state at this time is again determined.
Compared with the prior art, the invention has the following advantages:
1. Because of the situation that the knock sensor detection signal has false alarm or false detection at present, the 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 engine operation, and protect the safe operation of the engine;
2. the invention adopts a knock grading control strategy, can reduce the adverse effect of knocking on the running of the engine, and effectively improves the dynamic property and economy of the engine.
Drawings
FIG. 1 is a flow chart diagram of spark-ignition engine knock signal identification and level discrimination, i.e., knock condition diagnostics.
FIG. 2 is a schematic flow chart of spark-ignition engine knock staging control.
Detailed Description
The invention is described in further detail below with reference to the drawings and the detailed description.
As shown in fig. 1, the ignition engine knock signal identification and level differentiation, i.e., knock state diagnosis method is as follows:
And acquiring a cylinder pressure signal of the ignition engine through a cylinder pressure sensor, wherein the cylinder pressure signal enters a signal processing module. In the signal processing module, two methods of lifting wavelet transformation and empirical mode decomposition are adopted to analyze the combustion state so as to provide basis for diagnosis of knocking signals. The wavelet transformation method has the characteristic that the time resolution and the frequency resolution are self-adaptive along with the frequency change in fault diagnosis, wavelet energy of wavelet transformation on different scales can be calculated as diagnosis characteristic quantity by carrying out wavelet transformation on cylinder pressure signals, so that characteristic parameters of combustion state are obtained, and fault diagnosis of engine knocking combustion is realized. Based on the analysis result of the signal processing module, the combustion state is determined. In the case of abnormal combustion conditions, it is necessary to define the knock intensity based on the wavelet energy, which is defined as mild knock, moderate knock, and severe knock, respectively.
At present, a knock sensor is generally assembled on a spark ignition engine, and can generate a corresponding voltage signal by detecting vibration of the spark ignition engine, and a corresponding knock characteristic frequency can be obtained by carrying out low-pass filtering and band-pass filtering signal processing on the signal. Based on a cylinder pressure signal of a cylinder pressure sensor, the knock characteristic frequency is partitioned to obtain corresponding knock thresholds, namely a knock threshold A, a knock threshold B and a knock threshold C, wherein the numerical relation of the knock thresholds is as follows: knock threshold a < knock threshold B < knock threshold C. In this embodiment, taking an ignition engine with a displacement of 13L as an example, the knock threshold a is 0.50, the knock threshold B is 0.75, and the knock threshold C is 0.85 through test calibration.
And performing off-line comparison analysis on the cylinder pressure signal processed by the signal processing module and the processed signal of the knock sensor, and establishing a mapping relation between the knock intensity signal and the knock threshold value.
Mild knock corresponds to knock threshold a, moderate knock corresponds to knock threshold B, and severe knock corresponds to knock threshold C.
Based on the result of the knock characteristic frequency classification, each knock threshold corresponds to a corresponding ignition timing retard step, respectively. The knock threshold A corresponds to the ignition timing back step A, the knock threshold B corresponds to the ignition timing back step B, and the knock threshold C corresponds to the ignition timing back step C.
The numerical relation of the ignition time push-back step length is as follows: the ignition timing retard step A < ignition timing retard step B < ignition timing retard step C.
In this embodiment, the ignition timing post-step a is 0.2 ° CA, the ignition timing post-step B is 0.6 ° CA, and the ignition timing post-step C is 1.0 ° CA. Where ° CA represents the crank angle.
As shown in fig. 2, the ignition engine knock grading control method is as follows:
When the ignition engine is running, firstly, the running condition, ignition time and knock sensor signals of the current ignition engine are obtained.
1. It is determined whether the current knock signal exceeds a knock threshold C.
If yes, judging that the in-cylinder combustion is in a heavy knocking state, immediately retarding the ignition moment, and pushing the ignition moment by a step length C. After the ignition timing is updated, it is newly determined whether the current knock signal exceeds the knock threshold C.
If not, the next judging process is entered.
2. It is determined whether or not the knock signal exceeds the knock threshold B, of course.
If yes, the in-cylinder combustion is judged to be in a medium knocking state, the ignition moment is immediately delayed, and the ignition moment is pushed by a step length B. After the ignition time is updated, whether the current knock signal exceeds a knock threshold C and a knock threshold B is judged again.
If not, the next judging process is entered.
3. It is determined whether the current knock signal exceeds a knock threshold a.
If yes, the in-cylinder combustion is judged to be in a light knocking state. The light knock contributes to the improvement of the economy of the spark-ignition engine. Therefore, it is not necessary to retard the ignition timing immediately at this time, and the ignition timing is retarded by step a after the engine is operated for a certain period of time (5 minutes). After the ignition timing is updated, it is newly determined whether the current knock signal exceeds the knock threshold C, the knock threshold B, and the knock threshold a.
If not, it is determined that knocking does not occur at this time. To further improve the economy of the engine, a more advanced ignition timing may be selected, with the ignition timing advanced by 0.5CA. Then, the combustion state at this time is again determined.
In the case of the knock state grading control, the ignition timing adjustment follows the principle of fast reverse and slow reverse. I.e. if there is no heavy knock at this time, the ignition timing is quickly adjusted. As the knock intensity decreases, the step size after the ignition timing decreases. When knocking does not occur, the ignition time is slowly advanced, the fuel combustion efficiency and the working capacity are improved, and the economy of the engine is further improved.
Claims (4)
1. A method for diagnosing and grading the knocking state of an ignition engine is characterized in that: the method comprises the following steps:
Step 1: acquiring a pressure signal of a cylinder of the ignition engine through a cylinder pressure sensor and analyzing a combustion state by adopting a signal processing module;
Step 2: based on the analysis result of the signal processing module, defining the knock intensity as the square integral result of the signal in the knock calculation window for representing the knock level, wherein the calculation formula is as follows:
Wherein: n is the number of data points of the knock calculation window;
x (i) is pressure data after signal processing;
Defining knock intensity based on knock intensity data, which is respectively defined as light knock, medium knock and heavy knock;
step 3: the method comprises the steps that a knock sensor detects vibration of an ignition engine and generates corresponding voltage signals, corresponding knock characteristic frequencies are obtained through low-pass filtering and band-pass filtering signal processing of the voltage signals, and the knock characteristic frequencies are classified based on cylinder pressure signals of a cylinder pressure sensor to obtain corresponding knock thresholds, namely a knock threshold A, a knock threshold B and a knock threshold C; the numerical relationship of the knock threshold is: knock threshold a < knock threshold B < knock threshold C;
Step 4: performing off-line comparison analysis on the cylinder pressure signal processed by the signal processing module and the processed signal of the knock sensor, and establishing a mapping relation between the knock intensity signal and the knock threshold value: mild knock corresponds to knock threshold a, moderate knock corresponds to knock threshold B, and severe knock corresponds to knock threshold C;
Step 5: based on the result of the knock characteristic frequency classification, each knock threshold corresponds to a corresponding ignition timing post step size: the knocking threshold A corresponds to the ignition moment backward step length A, the knocking threshold B corresponds to the ignition moment backward step length B, and the knocking threshold C corresponds to the ignition moment backward step length C; the numerical relation of the ignition time push-back step length is as follows: the ignition time back step length A is smaller than the ignition time back step length B is smaller than the ignition time back step length C;
Step 6: judging whether the current knocking signal exceeds a knocking threshold C, if so, judging that the in-cylinder combustion is in a heavy knocking state at the moment, and immediately retarding the ignition moment by a step length C after the ignition moment; after the ignition time is updated, whether the current knocking signal exceeds a knocking threshold C or not is judged again, and if not, the next judging process is carried out;
Step 7: judging whether the knocking signal exceeds a knocking threshold B or not, if so, judging that the in-cylinder combustion is in a medium knocking state at the moment, and immediately retarding the ignition moment, wherein the ignition moment is pushed back by a step length B; after the ignition time is updated, whether the current knock signal exceeds a knock threshold C and a knock threshold B is judged again, and if not, the next judging process is carried out;
Step 8: judging whether the current knocking signal exceeds a knocking threshold A, if so, judging that the in-cylinder combustion is in a mild knocking state, and immediately retarding the ignition moment, wherein after the engine runs for a preset time, the ignition moment is pushed by a step length A; after the ignition time is updated, whether the current knock signal exceeds a knock threshold C, a knock threshold B and a knock threshold A is judged again, and if not, knocking does not occur at the moment.
2. The method for diagnosing and controlling the knocking state of an ignition engine according to claim 1, wherein: in the step 1, a signal processing module analyzes a combustion state by adopting a lifting wavelet transformation method and an empirical mode decomposition method; the wavelet transformation method has the characteristic that the time resolution and the frequency resolution are self-adaptive along with the frequency change in fault diagnosis, and wavelet energy of wavelet transformation on different scales is calculated as diagnosis characteristic quantity by carrying out wavelet transformation on cylinder pressure signals, so that the characteristic parameter of the combustion state is obtained.
3. A method of diagnosing and staging engine knock condition according to claim 2 wherein: in the case of abnormal combustion conditions, it is necessary to define the knock intensity based on the wavelet energy, which is defined as mild knock, moderate knock, and severe knock, respectively.
4. The method for diagnosing and controlling the knocking state of an ignition engine according to claim 1, wherein: in the step 6, if the knocking is not generated at the moment, the ignition time which is advanced more is selected, and the ignition time is advanced by 0.5 degrees CA; the combustion state at this time is then again determined, where ° CA represents the crank angle.
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| CN202410475787.0A CN118188186A (en) | 2024-04-19 | 2024-04-19 | Method for diagnosing and grading control of knocking state of ignition engine |
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| CN202410475787.0A CN118188186A (en) | 2024-04-19 | 2024-04-19 | Method for diagnosing and grading control of knocking state of ignition engine |
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