A calibration method and calibration system for an engine

Abstract

The application provides a kind of calibration method and calibration system of engine, it is related to engine technical field, the calibration method includes: when engine is in knock state, control engine reduces ignition advance angle and obtains the vibration data in time domain within single cycle, wherein vibration data includes vibration intensity and corresponding time;In the whole time domain of vibration data, multiple sub-time regions are divided, and the vibration data in each sub-time region is time-frequency converted to obtain the vibration spectrum corresponding to each sub-time region, wherein the vibration spectrum includes the vibration power corresponding to different frequencies;In high frequency region, each vibration spectrum is integrated to obtain signal intensity and the sub-time region and frequency band corresponding to signal intensity;When signal intensity is greater than a predetermined threshold, the sub-time region and frequency band corresponding to signal intensity are calibrated as high frequency background noise region.The method effectively identifies high frequency background noise band, reduces the interference to real knock calibration, and shortens the time of knock calibration.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and in particular to an engine calibration method and calibration system. Background Technology

[0002] When an engine draws in a mixture of fuel vapor and air, and before the compression stroke reaches the designed ignition point, various factors beyond control can cause the mixture to spontaneously ignite and burn. At this point, the enormous impact force generated by combustion is opposite to the direction of piston movement, causing engine vibration. This phenomenon is called knocking. Knocking often results in severe knocking noise and damage to the thermal boundary layer of the combustion chamber, increasing the engine's mechanical and thermal loads and causing serious damage. Therefore, in the field of engine control, employing effective methods to detect and identify knocking and suppress its occurrence is essential.

[0003] Meanwhile, the power density and compression ratio of modern engines are getting higher and higher, which causes the engine to generate strong high-frequency background noise even without knocking under high speed and heavy load conditions. In the entire knocking window, the knocking frequency band and the high-frequency background noise frequency band will be mixed together, making it impossible to distinguish between real knocking and high-frequency background noise. At present, relevant knocking identification strategies not only require the use of special equipment, but also require a lot of wiring harnesses and involve a lot of equipment. The calibration process is complicated and time-consuming, and it is impossible to accurately identify the high-frequency background noise frequency band. Summary of the Invention

[0004] This invention provides an engine calibration method and calibration system to solve the technical problem of how to accurately and quickly identify high-frequency background noise bands and improve the efficiency of engine calibration.

[0005] This invention provides a calibration method for an engine, comprising: when the engine is in a knock state, controlling the engine to reduce the ignition advance angle and acquiring vibration data in the time domain within a single cycle, wherein the vibration data includes vibration intensity and corresponding time; dividing the entire time domain of the vibration data into multiple sub-time regions, performing time-frequency conversion on the vibration data in each sub-time region to obtain a vibration spectrum corresponding to each sub-time region, wherein the vibration spectrum includes vibration power corresponding to different frequencies; performing definite integral on each vibration spectrum in a high-frequency region to obtain a signal intensity and a sub-time region and frequency band corresponding to the signal intensity; when the signal intensity is greater than a preset threshold, calibrating the sub-time region and frequency band corresponding to the signal intensity as a high-frequency background noise region.

[0006] Furthermore, dividing the vibration data into multiple sub-time regions within the entire time domain includes: uniformly dividing the vibration data into multiple sub-time regions within the entire time domain.

[0007] Furthermore, dividing the vibration data into multiple sub-time regions within the entire time domain includes dividing the vibration data into multiple sub-time regions, with the interval between the sub-time regions being smaller the closer to the ignition advance angle.

[0008] Furthermore, the step of controlling the engine to reduce the ignition advance angle and acquiring vibration data in the time domain within a single cycle when the engine is in a knock state includes: controlling the engine to reduce the ignition advance angle and acquiring vibration data in the time domain within a single cycle when the engine is in a knock state, wherein the length of the time domain is the minimum length between the theoretical value calculated based on the bench equipment parameters and the actual value measured for the knock state time length.

[0009] Furthermore, the step of performing time-frequency conversion on the vibration data in each of the sub-time regions to obtain the vibration spectrum corresponding to each of the sub-time regions includes: performing offline analysis on the vibration data in each of the sub-time regions, and transforming the vibration data through Fourier transform to obtain the vibration spectrum corresponding to each of the sub-time regions.

[0010] Furthermore, the step of performing definite integration on each of the vibration spectra in the high-frequency region includes: filtering out the high-frequency region within the vibration spectrum using a filtering device, and performing definite integration on each of the vibration spectra in the high-frequency region.

[0011] Further, after calibrating the sub-time region and frequency band corresponding to the signal strength as a high-frequency background noise region, the calibration method further includes: keeping the engine's operating condition unchanged, repeating the process of controlling the engine to reduce the ignition advance angle and acquiring vibration data in the time domain within a single cycle while the engine is in a knock state, wherein the vibration data includes vibration intensity and the corresponding time; dividing the entire time domain of the vibration data into multiple sub-time regions, performing time-frequency conversion on the vibration data in each sub-time region to obtain the vibration spectrum corresponding to each sub-time region, wherein the vibration spectrum includes vibration power corresponding to different frequencies; performing definite integration on each vibration spectrum in the high-frequency region to obtain the signal strength and the sub-time region and frequency band corresponding to the signal strength; when the signal strength is greater than a preset threshold, calibrating the sub-time region and frequency band corresponding to the signal strength as a high-frequency background noise region until the number of repetitions reaches the first threshold; and calibrating all the high-frequency background noise regions as the overall high-frequency background noise region.

[0012] Further, by performing a definite integral on each vibration spectrum in the high-frequency region to obtain the signal strength and the sub-time region and frequency band corresponding to the signal strength, and when the signal strength is greater than a preset threshold, the sub-time region and frequency band corresponding to the signal strength are calibrated to the high-frequency background noise region. The calibration method further includes: keeping the engine operating condition unchanged, repeating the process of controlling the engine to reduce the ignition advance angle and acquiring vibration data in the time domain within a single cycle when the engine is in a knock state, wherein the vibration data includes vibration intensity and the corresponding time; dividing the entire time domain of the vibration data into multiple sub-time regions, and performing time-frequency conversion on the vibration data in each sub-time region to obtain the vibration spectrum corresponding to each sub-time region, wherein the vibration spectrum includes different The vibration power corresponding to the frequency; definite integration of each vibration spectrum in the high-frequency region to obtain the signal strength and the sub-time region and frequency band corresponding to the signal strength until the number of repetitions reaches the second threshold; when the signal strength is greater than the preset threshold, the sub-time region and frequency band corresponding to the signal strength are labeled as high-frequency background noise regions, including: determining the parts where the sub-time region and the frequency band are the same as the overlapping region, and determining at least one different part of the sub-time region and the frequency band as the non-overlapping region; in the overlapping region, the average value of the signal strength is calculated, and when the average value is greater than the preset threshold, the overlapping region is labeled as a high-frequency background noise region; in the non-overlapping region, when the signal strength is greater than the preset threshold, the non-overlapping region is labeled as a high-frequency background noise region.

[0013] Further, after calibrating the sub-time region and frequency band corresponding to the signal strength as a high-frequency background noise region, the calibration method further includes: changing the engine's operating conditions, repeating the process of controlling the engine to reduce the ignition advance angle and acquiring vibration data in the time domain within a single cycle when the engine is in a knock state, wherein the vibration data includes vibration intensity and the corresponding time; dividing the entire time domain of the vibration data into multiple sub-time regions, performing time-frequency conversion on the vibration data in each sub-time region to obtain the vibration spectrum corresponding to each sub-time region, wherein the vibration spectrum includes vibration power corresponding to different frequencies; performing definite integral on each vibration spectrum in the high-frequency region to obtain the signal strength and the sub-time region and frequency band corresponding to the signal strength; when the signal strength is greater than a preset threshold, calibrating the sub-time region and frequency band corresponding to the signal strength as a high-frequency background noise region until all operating conditions requiring calibration are marked; and summarizing the marked high-frequency background noise regions under each operating condition.

[0014] Further, the calibration system is used to execute the calibration method according to any one of claims 1 to 9, the calibration system comprising: a processing module for controlling the engine to reduce the ignition advance angle; and an acquisition module for acquiring vibration data in the time domain within a single cycle; the processing module is further configured to divide the vibration data into multiple sub-time regions within the entire time domain, and perform time-frequency conversion on the vibration data in each sub-time region to obtain the vibration spectrum corresponding to each sub-time region; the processing module is further configured to perform definite integral on each vibration spectrum in the high-frequency region to obtain the signal strength and the sub-time region and frequency band corresponding to the signal strength; and the processing module is further configured to, when the signal strength is greater than a preset threshold, calibrate the sub-time region and frequency band corresponding to the signal strength as a high-frequency background noise region.

[0015] This invention provides a calibration method for an engine, comprising: when the engine is in a knock state, controlling the engine to reduce the ignition advance angle and acquiring vibration data in the time domain within a single cycle, wherein the vibration data includes vibration intensity and the corresponding time; dividing the entire time domain of the vibration data into multiple sub-time regions, performing time-frequency conversion on the vibration data in each sub-time region to obtain the vibration spectrum corresponding to each sub-time region, wherein the vibration spectrum includes vibration power corresponding to different frequencies; performing definite integral on each vibration spectrum in the high-frequency region to obtain the signal intensity and the sub-time region and frequency band corresponding to the signal intensity; when the signal intensity is greater than a preset threshold, calibrating the sub-time region and frequency band corresponding to the signal intensity as a high-frequency background noise region. By reducing the ignition advance angle at a single engine operating point, the high-frequency background noise band within the background noise frequency band can be accurately identified. Through vibration data analysis, the high-frequency background noise band can be precisely identified, achieving accurate differentiation from actual knock while reducing interference with actual knock calibration. This significantly shortens the knock calibration time, reduces bench occupancy, and improves the efficiency of engine calibration. Furthermore, by correlating signal strength with sub-time regions and frequency bands, the high-frequency background noise region can be more directly determined. This facilitates accurate identification of different knock frequency bands and high-frequency background noise bands under different knock conditions at various operating points, thereby improving the accuracy of knock calibration at each operating point. Attached Figure Description

[0016] Figure 1 An engine calibration method provided in an embodiment of the present invention;

[0017] Figure 2 Another engine calibration method provided in this embodiment of the invention;

[0018] Figure 3 Another engine calibration method provided in this embodiment of the invention;

[0019] Figure 4 Another engine calibration method provided in this embodiment of the invention;

[0020] Figure 5 Another engine calibration method provided in this embodiment of the invention;

[0021] Figure 6 Another engine calibration method provided in this embodiment of the invention;

[0022] Figure 7 Another engine calibration method provided in this embodiment of the invention;

[0023] Figure 8 Another engine calibration method provided in this embodiment of the invention;

[0024] Figure 9 This is a schematic diagram of a calibration system provided in an embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0026] The specific technical features described in the specific embodiments can be combined in any suitable manner without contradiction. For example, different combinations of specific technical features can form different embodiments and technical solutions. To avoid unnecessary repetition, the various possible combinations of the specific technical features in this invention will not be described separately.

[0027] In the following description, the terms "first," "second," etc., are used merely to distinguish different objects and do not indicate that the objects have the sameness or relationship. It should be understood that the directional descriptions "above," "below," "outside," and "inside" refer to the orientation under normal use conditions, while "left" and "right" refer to the left and right directions shown in the corresponding diagrams, which may or may not be the left and right directions under normal use conditions.

[0028] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. The term "connection," unless otherwise specified, includes both direct and indirect connections.

[0029] The calibration method and calibration system provided in the following specific embodiments are applicable to any type of engine. For example, the calibration method and calibration system are applicable to gasoline engines; for example, the calibration method and calibration system are applicable to diesel engines. For ease of explanation, the following description uses the calibration method and calibration system applicable to gasoline engines as an example.

[0030] In some embodiments, such as Figure 1 As shown, Figure 1 A flowchart illustrating an engine calibration method is provided, the process of which includes:

[0031] Step S1: When the engine is in a knock state, control the engine to reduce the ignition advance angle and acquire vibration data in the time domain within a single cycle, wherein the vibration data includes vibration intensity and the corresponding time.

[0032] Specifically, after starting the engine on a test bench and placing it in a knocking state, knock sensors can be installed at different locations on the engine. Vibration data from these sensors at different engine locations is then acquired to confirm that the engine is in a knocking state. While the engine is in a knocking state, reducing the ignition advance angle can suppress actual knocking. High-frequency background noise, however, cannot be suppressed and may still exist, thus differentiating between actual knocking noise and high-frequency background noise. Vibration data in the time domain is acquired within a single cycle, with 720 degrees of crankshaft rotation constituting one cycle. To improve the accuracy of the vibration data, vibration data in the time domain across multiple engine cycles can be collected. Furthermore, to avoid excessively long data processing times and improve efficiency, 300 cycles of vibration data can be collected for each cylinder. The vibration data includes vibration intensity and the corresponding time. Vibration intensity can be understood as the electrical signal from the knock sensor, and the corresponding time corresponds to the crankshaft rotation angle.

[0033] Step S2: Divide the vibration data into multiple sub-time regions within the entire time domain, and perform time-frequency conversion on the vibration data in each sub-time region to obtain the vibration spectrum corresponding to each sub-time region, wherein the vibration spectrum includes the vibration power corresponding to different frequencies.

[0034] Specifically, the vibration data is divided into multiple sub-time regions within the entire time domain. It should be noted that the entire time domain refers to the vibration data within the window of the knock duration of one cylinder cycle. The entire time domain, i.e., the knock duration, is divided into multiple time intervals, each of which is a sub-time region. The length of each sub-time region can be the same or different; the specific differences will be described below. Each sub-time region corresponds to specific vibration data. Time-frequency conversion is performed on the vibration data within each sub-time region to obtain the vibration spectrum corresponding to that sub-time region. This process can be performed on a test bench or offline. The specific conversion method is not limited. For example, using a Matlab program, the knock sensor electrical signal of the vibration data within each sub-time region is subjected to Fourier transform to obtain the vibration spectrum corresponding to each sub-time region, i.e., the frequency signal within the frequency domain. The vibration spectrum includes the vibration power corresponding to different frequencies.

[0035] Step S3: Perform definite integral on each vibration spectrum in the high-frequency region to obtain the signal intensity and the corresponding sub-time region and frequency band.

[0036] Specifically, definite integrals are performed on each vibration spectrum in the high-frequency region. It should be noted that background noise includes high-frequency background noise and low-frequency background noise. Low-frequency background noise is easy to distinguish, while high-frequency background noise is mixed with detonation and is not easy to distinguish. Therefore, low-frequency noise can be filtered out from the background noise. In the high-frequency region, definite integrals are performed on each vibration spectrum, that is, the frequency signal after Fourier transform within a single cycle is integrated to obtain the signal strength KP (the detonation intensity calculated by the combustion analyzer, hereinafter KP refers to the detonation intensity) and the sub-time region and frequency band corresponding to the signal strength KP.

[0037] Step S4: When the signal strength is greater than a preset threshold, the sub-time region and frequency band corresponding to the signal strength are calibrated as high-frequency background noise region.

[0038] Specifically, the signal strength KP value exists within a range, and the specific value of the range is not limited. When the signal strength KP is greater than a preset threshold, the sub-time region and frequency band corresponding to the signal strength KP are marked as a high-frequency background noise region. The specific threshold value can be determined according to the actual situation. For example, if the preset threshold is Q, and the signal strength KP is greater than Q, then the sub-time region and frequency band corresponding to the signal strength KP are marked as a high-frequency background noise region. If the signal strength KP is less than or equal to Q, then the sub-time region and frequency band corresponding to the signal strength KP are not processed in any way and can be understood as the real knock zone.

[0039] For ease of observation and calibration, the entire time domain (angular domain data) and frequency domain data obtained in each cycle, i.e., the frequency signal within the frequency domain (frequency domain data), can be visualized using signal strength KP to generate a signal analysis graph in a two-dimensional plane. The horizontal axis of the signal analysis graph is defined as the signal angular domain, the vertical axis as the signal frequency domain, and the vertical axis as the signal strength KP. The vertical axis can be understood as the coordinate axis perpendicular to the plane formed by the horizontal and vertical axes. The starting value of the signal angular domain on the horizontal axis of the signal analysis graph is defined as 'a' using the engine's CA50 (the operating condition determined in the combustion analyzer) under the current operating conditions. The length of the signal angular domain can be a theoretical value calculated based on the bench equipment parameters or an actual value measured for the duration of the knocking state. To reduce processing time and improve efficiency for subsequent visualization, the length can be the minimum length 'a1' between the theoretical value calculated based on the bench equipment parameters and the actual value measured for the duration of the knocking state; that is, the range of the signal angular domain on the horizontal axis is from 'a' to 'a+a1'. In the signal analysis graph, the vertical axis represents the signal frequency domain. By default, signal frequencies below A are considered low-frequency noise, i.e., mechanical noise, and can be ignored. Therefore, the starting value of the signal frequency domain is defined as A. Based on engineering experience, the maximum background noise frequency is A+A1, so the length of the signal frequency domain is defined as A1, meaning the vertical axis ranges from A to A+A1. The vertical axis represents the signal strength axis. The starting value of the signal strength axis is the minimum value x of the signal strength KP in that cycle, and the ending value is the maximum value y of the signal strength KP in that cycle. Therefore, the vertical axis ranges from x to y. By hiding the vertical axis (signal strength axis), the signal analysis graph ultimately presents a two-dimensional planar effect. In the resulting signal analysis graph, the high-frequency background noise band is distinguished by a different color from other noise bands, and the area color within the plane changes from blue to yellow as the signal strength KP value increases.

[0040] Once the range of the signal frequency domain is determined, and the engine is operating in a non-knock state or in a state where the ignition advance angle is artificially reduced to suppress knock, a background noise band will be formed within the range of the signal angular domain and the signal frequency domain. The starting position and frequency band length of the background noise band can be determined through the vibration spectrum. For example, the starting position B and the frequency band length B1, where B≥A and B1≤A1. Through the signal analysis graph, the starting position b and the frequency band length b1 of the background noise band in the signal angular domain are confirmed, where b≥a and b1≤a1. That is, under the current engine operating conditions, the horizontal axis of the signal analysis graph has a signal angular domain range from b to b+b1, and the vertical axis has a signal frequency domain range from B to B+B1.

[0041] When an engine operates in a non-knock state, or after artificially reducing the ignition advance angle to suppress knock under knock conditions, multiple high-frequency background noise bands will be generated in the background noise frequency band. The specific number depends on the actual situation. In the resulting signal analysis diagram, the high-frequency background noise bands are distinguished by color from other background noise bands; the area containing the high-frequency background noise band is yellow, and other areas are blue. During engine calibration, it is necessary to remove the identified high-frequency background noise bands. This can be done by filling in the High-Frequency Background Noise Band Determination MAP table. The default value in the MAP table is 0, and -1 indicates that the high-frequency background noise band can be removed. For example, given three high-frequency background noise bands, in the signal analysis graph, the first yellow area represents the first high-frequency background noise band. The starting position (C) and length (C1) of the signal frequency domain of this band, as well as the starting position (c) and length (c1) of the signal angular domain of this band, are considered high-frequency background noise bands. The area on the horizontal axis (signal angular domain range) from c to c+c1, and the area on the vertical axis (signal frequency domain range) from C to C+C1, is recorded as -1 in the high-frequency background noise band determination MAP table. Similarly, in the signal analysis graph, the second yellow area represents the second high-frequency background noise band. This band is located on the horizontal axis (signal angular domain range) from d to d+d1, and the vertical axis (signal frequency domain range) from D to D+D1. This high-frequency background noise band is also recorded as -1 in the high-frequency background noise band determination MAP table. In the signal analysis graph, the third yellow area represents the third high-frequency background noise band. This high-frequency background noise band ranges from e to e+e1 in the angular domain (horizontal axis) and from E to E+E1 in the frequency domain (vertical axis). This high-frequency background noise band can be recorded as -1 in the High-Frequency Background Noise Band Determination MAP table. The absence of a yellow area in the signal analysis graph indicates the absence of high-frequency background noise under this condition; in this case, the High-Frequency Background Noise Band Determination MAP table remains at its default value of 0.

[0042] This invention provides a calibration method for an engine, comprising: when the engine is in a knock state, controlling the engine to reduce the ignition advance angle and acquiring vibration data in the time domain within a single cycle, wherein the vibration data includes vibration intensity and the corresponding time; dividing the entire time domain of the vibration data into multiple sub-time regions, performing time-frequency conversion on the vibration data in each sub-time region to obtain the vibration spectrum corresponding to each sub-time region, wherein the vibration spectrum includes vibration power corresponding to different frequencies; performing definite integral on each vibration spectrum in the high-frequency region to obtain the signal intensity and the sub-time region and frequency band corresponding to the signal intensity; when the signal intensity is greater than a preset threshold, calibrating the sub-time region and frequency band corresponding to the signal intensity as a high-frequency background noise region. By reducing the ignition advance angle at a single engine operating point, the high-frequency background noise band within the background noise frequency band can be accurately identified. Through vibration data analysis, the high-frequency background noise band can be precisely identified, achieving accurate differentiation from actual knock while reducing interference with actual knock calibration. This significantly shortens the knock calibration time, reduces bench occupancy, and improves the efficiency of engine calibration. Furthermore, by correlating signal strength with sub-time regions and frequency bands, the high-frequency background noise region can be more directly determined. This facilitates accurate identification of different knock frequency bands and high-frequency background noise bands under different knock conditions at various operating points, thereby improving the accuracy of knock calibration at each operating point.

[0043] In some embodiments, such as Figure 2 As shown, Figure 2 A flowchart illustrating another engine calibration method is provided, which is similar to... Figure 1 The calibration methods provided are different. Figure 2 Step S2 includes:

[0044] Step S21: Divide the vibration data into multiple sub-time regions evenly over the entire time domain.

[0045] Specifically, the vibration data in the entire time domain refers to the vibration data within the window of the knock duration of one cylinder cycle. The entire time domain, i.e. the knock duration, is divided into multiple time intervals. The vibration data corresponding to each sub-time region is processed. In order to improve the speed of subsequent data processing and accelerate the overall calibration efficiency, the entire time domain is evenly divided into multiple sub-time regions.

[0046] Step S22: Perform time-frequency conversion on the vibration data in each sub-time region to obtain the vibration spectrum corresponding to each sub-time region, wherein the vibration spectrum includes the vibration power corresponding to different frequencies.

[0047] The specific details have already been described above and will not be repeated here.

[0048] In some embodiments, such as Figure 3As shown, Figure 3 A flowchart illustrating another engine calibration method is provided, which is similar to... Figure 1 The calibration methods provided are different. Figure 3 Step S2 includes:

[0049] Step S23: Divide the vibration data into multiple sub-time regions within the entire time domain. The closer to the ignition advance angle, the smaller the interval between the sub-time regions.

[0050] Specifically, the entire time domain, i.e., the detonation duration, is divided into multiple time intervals. The vibration data corresponding to each sub-time region is processed. To improve the accuracy of subsequent labeling, the smaller the interval between sub-time regions, the more accurate the subsequent calculation and calibration will be. However, this will increase the data processing time. Since detonation occurs in the time range close to the ignition advance angle, while ensuring accuracy, the data processing time can be minimized as much as possible. This can be achieved by dividing the time domain unevenly, with the interval between sub-time regions being smaller closer to the ignition advance angle. The specific interval time can be determined according to the actual situation, thus satisfying both accuracy and controlling the data processing time.

[0051] Step S22, the details of which have been described above, will not be repeated here.

[0052] In some embodiments, such as Figure 4 As shown, Figure 4 A flowchart illustrating another engine calibration method is provided, which is similar to... Figure 1 The calibration methods provided are different. Figure 4 Step S2 includes:

[0053] Step S24: Divide the vibration data into multiple sub-time regions within the entire time domain.

[0054] The specific details have already been described above and will not be repeated here.

[0055] Step S25: Perform offline analysis on the vibration data in each sub-time region, and transform the vibration data through Fourier transform to obtain the vibration spectrum corresponding to each sub-time region.

[0056] Specifically, vibration data within a sub-time region can be analyzed online using a computer on the test bench. To save time, the vibration data can be copied offline for offline analysis. Using a Matlab program on an offline computer, the electrical signals in the vibration data can be transformed using Fourier transform to obtain the vibration spectrum corresponding to each sub-time region.

[0057] In some embodiments, such as Figure 5 As shown, Figure 5 A flowchart illustrating another engine calibration method is provided, which is similar to... Figure 1 The calibration methods provided are different. Figure 5 Step S3 includes:

[0058] Step 31: Use a filtering device to filter out the high-frequency region within the vibration spectrum, and perform definite integral on each vibration spectrum within the high-frequency region.

[0059] Specifically, background noise includes high-frequency background noise and low-frequency background noise. Low-frequency background noise is easy to distinguish, while high-frequency background noise is mixed with knock and is not easy to distinguish. In order to reduce the time of subsequent data processing, a filtering device can be added, such as a filter to filter out low-frequency noise from the background noise, and then high-frequency noise can be selected. In the high-frequency region, definite integrals are performed on each vibration spectrum.

[0060] In some embodiments, such as Figure 6 As shown, Figure 6 A flowchart illustrating another engine calibration method is provided, which is similar to... Figure 1 The calibration methods provided are different. Figure 6 Following step S4, the calibration method further includes:

[0061] Step S5: Keep the engine operating conditions unchanged and repeat steps S1 to S4 until the number of repetitions reaches the first threshold.

[0062] Specifically, in order to improve the accuracy of calibration, multiple tests can be conducted under the same operating conditions of the engine to obtain data for analysis. The specific number of repetitions can be determined according to the actual situation. For example, the threshold for the first count is 300, that is, 300 cycles of vibration data are collected. The vibration data includes vibration intensity and corresponding time. Then, these 300 cycles of vibration data are processed sequentially, and the high-frequency background noise region is calibrated for each cycle.

[0063] Step S6: Define all high-frequency background noise regions as the overall high-frequency background noise region.

[0064] Specifically, the high-frequency background noise region was calibrated in each cycle to avoid the randomness of the test results. The high-frequency background noise regions calibrated in 300 cycles can be combined and all high-frequency background noise regions can be calibrated as the overall high-frequency background noise region to avoid omission of high-frequency background noise regions.

[0065] In some embodiments, such as Figure 7 As shown, Figure 7 A flowchart illustrating another engine calibration method is provided, which is similar to... Figure 1 The calibration methods provided are different. Figure 7 Following step S4, the calibration method further includes:

[0066] Step S7: Keep the engine operating conditions unchanged, and repeat steps S1 to S3 until the number of repetitions reaches the second threshold.

[0067] Specifically, to improve the accuracy of calibration, multiple tests can be conducted under the same engine operating conditions to obtain data for analysis. The specific number of repetitions can be determined according to the actual situation. For example, the threshold for the second test is 300, that is, 300 cycles of vibration data are collected. The vibration data includes vibration intensity and the corresponding time. Then, these 300 cycles of vibration data are processed sequentially, and each cycle yields the signal intensity KP and the sub-time region and frequency band corresponding to the signal intensity KP.

[0068] In step S4 of the calibration method, when the signal strength is greater than a preset threshold, the sub-time region and frequency band corresponding to the signal strength are calibrated as high-frequency background noise regions, including:

[0069] Step S41: Identify the parts where both the sub-time region and the frequency band are the same as the overlapping region, and identify the parts where at least one of the sub-time region and the frequency band is different as the non-overlapping region.

[0070] Specifically, in the 300 cycles of vibration data, the signal intensity KP obtained from different cycles and the corresponding sub-time regions and frequency bands are different, with some overlapping and some not. For the parts where both the sub-time regions and frequency bands are the same, the overlapping region is defined as the part where at least one part of the sub-time region and frequency band is different, and the non-overlapping region is defined as the part where at least one part of the sub-time region and frequency band is different. This can be understood as the region surrounded by the sub-time region and frequency band in one cycle not overlapping with the region generated by other cycles, which is the non-overlapping region.

[0071] Step S42: Within the overlapping area, calculate the average signal strength. If the average value is greater than a preset threshold, the overlapping area is marked as a high-frequency background noise area. In the non-overlapping area, if the signal strength is greater than the preset threshold, the non-overlapping area is marked as a high-frequency background noise area.

[0072] Specifically, for overlapping regions, in order to improve the accuracy of calibration, the signal strength KP of the overlapping regions is calculated to obtain the average value of the signal strength KP. If the average value is greater than a preset threshold, for example, the preset threshold is Q, the overlapping region is calibrated as a high-frequency background noise region; otherwise, it is not calibrated. In non-overlapping regions, if the signal strength KP is greater than the preset threshold, that is, if the signal strength KP is greater than Q, the non-overlapping region is calibrated as a high-frequency background noise region; otherwise, it is not calibrated.

[0073] In some embodiments, such as Figure 8 As shown, Figure 8 A flowchart illustrating another engine calibration method is provided, which is similar to... Figure 1 The calibration methods provided are different. Figure 8 Following step S4, the calibration method further includes:

[0074] Step S8: Change the engine's operating conditions and repeat steps S1 to S4 until all operating conditions that need to be calibrated are marked.

[0075] Specifically, after the engine is calibrated under one operating condition, the engine operating condition is changed to perform calibration for the next engine operating condition. Customized knock frequency band identification is performed at individual engine operating points, which effectively improves the accuracy of knock frequency band identification. At the same time, the knock frequency band and high-frequency noise frequency band are presented intuitively in the form of images under coordinate axes defined by the signal frequency domain and signal angle domain, which can be intuitively distinguished and judged, improving the efficiency of engine knock calibration, saving the workload of knock calibration, and shortening the knock calibration cycle.

[0076] Step S9: Summarize the marked high-frequency background noise regions under each working condition.

[0077] The present invention also provides a calibration system for performing some steps in the above calibration method. It can be understood that the steps of acquiring detonation data and processing the detonation data are all performed by the processing system.

[0078] In some embodiments, such as Figure 9 As shown, the processing system includes an acquisition module 100 and a processing module 200. The processing module 200 is used to control the engine to reduce the ignition advance angle, and the acquisition module 100 is used to acquire vibration data in the time domain within a single cycle. The processing module 200 is also used to divide the vibration data into multiple sub-time regions in the entire time domain, and perform time-frequency conversion on the vibration data in each sub-time region to obtain the vibration spectrum corresponding to each sub-time region. The processing module 200 is also used to perform definite integral on each vibration spectrum in the high-frequency region to obtain the signal strength and the sub-time region and frequency band corresponding to the signal strength. The processing module 200 is also used to label the sub-time region and frequency band corresponding to the signal strength as a high-frequency background noise region when the signal strength is greater than a preset threshold.

[0079] In some embodiments, such as Figure 9 As shown, the processing module 200 is further configured to uniformly divide the vibration data into multiple sub-time regions over the entire time domain. In some embodiments, such as Figure 9 As shown, the processing module 200 is further configured to divide the entire time domain of the vibration data into multiple sub-time regions, with the interval between the sub-time regions being smaller the closer to the ignition advance angle. In some embodiments, such as Figure 9As shown, the processing module 200 is also used to control the engine to reduce the ignition advance angle and acquire vibration data in the time domain within a single cycle when the engine is in a knock state. The acquisition module 100 is used to acquire the length of the time domain, which is the minimum length between the theoretical value calculated based on the bench equipment parameters and the actual value measured for the knock state time length.

[0080] In some embodiments, such as Figure 9 As shown, the processing module 200 is further configured to perform offline analysis of the vibration data in each sub-time region, and transform the vibration data using Fourier transform to obtain the vibration spectrum corresponding to each sub-time region. In some embodiments, such as Figure 9 As shown, the processing module 200 is also used to filter out the high-frequency region within the vibration spectrum through the filtering device, and to perform definite integral on each vibration spectrum within the high-frequency region.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A method for calibrating an engine, characterized in that, The calibration method includes: When the engine is in a knocking state, the engine is controlled to reduce the ignition advance angle and the vibration data in the time domain within a single cycle is acquired, wherein the vibration data includes the vibration intensity and the corresponding time. Within the entire time domain of the vibration data, multiple sub-time regions are divided, and the vibration data in each sub-time region are converted by time-frequency to obtain the vibration spectrum corresponding to each sub-time region, wherein the vibration spectrum includes vibration power corresponding to different frequencies; By performing a definite integral on each of the vibration spectra in the high-frequency region, the signal intensity and the sub-time region and frequency band corresponding to the signal intensity are obtained; When the signal strength is greater than a preset threshold, the sub-time region and frequency band corresponding to the signal strength are calibrated as a high-frequency background noise region.

2. The calibration method according to claim 1, characterized in that, Dividing the vibration data into multiple sub-time regions across the entire time domain includes: The vibration data is uniformly divided into multiple sub-time regions throughout the entire time domain.

3. The calibration method according to claim 1, characterized in that, Dividing the vibration data into multiple sub-time regions across the entire time domain includes: Within the entire time domain of the vibration data, multiple sub-time regions are divided, with the interval between the sub-time regions being smaller the closer to the ignition advance angle.

4. The calibration method according to claim 1, characterized in that, The step of controlling the engine to reduce the ignition advance angle and acquiring vibration data in the time domain within a single cycle when the engine is in a knock state includes: When the engine is in a knock state, the engine is controlled to reduce the ignition advance angle and the vibration data in the time domain within a single cycle is acquired. The length of the time domain is the minimum length between the theoretical value calculated based on the bench equipment parameters and the actual value measured for the knock state time length.

5. The calibration method according to claim 1, characterized in that, The step of performing time-frequency conversion on the vibration data within each of the sub-time regions to obtain the vibration spectrum corresponding to each sub-time region includes: The vibration data in each of the sub-time regions are analyzed offline, and the vibration data are transformed by Fourier transform to obtain the vibration spectrum corresponding to each of the sub-time regions.

6. The calibration method according to claim 1, characterized in that, The definite integral of each vibration spectrum in the high-frequency region includes: The high-frequency region within the vibration spectrum is selected by a filtering device, and the vibration spectrum is then integrally integrated within the high-frequency region.

7. The calibration method according to claim 1, characterized in that, After defining the sub-time region and frequency band corresponding to the signal strength as a high-frequency background noise region, the calibration method further includes: Keeping the engine operating conditions unchanged, repeat the process of controlling the engine to reduce the ignition advance angle and acquiring vibration data in the time domain within a single cycle when the engine is in a knock state, wherein the vibration data includes vibration intensity and corresponding time. Within the entire time domain of the vibration data, multiple sub-time regions are divided, and the vibration data in each sub-time region are converted by time-frequency to obtain the vibration spectrum corresponding to each sub-time region, wherein the vibration spectrum includes vibration power corresponding to different frequencies; By performing a definite integral on each of the vibration spectra in the high-frequency region, the signal intensity and the sub-time region and frequency band corresponding to the signal intensity are obtained; When the signal strength is greater than a preset threshold, the sub-time region and frequency band corresponding to the signal strength are calibrated as a high-frequency background noise region until the number of repetitions reaches the first threshold. All of the aforementioned high-frequency background noise regions are categorized as the overall high-frequency background noise region.

8. The calibration method according to claim 1, characterized in that, In the high-frequency region, a definite integral is performed on each of the vibration spectra to obtain the signal intensity and the sub-time region and frequency band corresponding to the signal intensity. When the signal intensity is greater than a preset threshold, the sub-time region and frequency band corresponding to the signal intensity are calibrated to the high-frequency background noise region. The calibration method further includes: Keeping the engine operating conditions unchanged, repeat the process of controlling the engine to reduce the ignition advance angle and acquiring vibration data in the time domain within a single cycle when the engine is in a knock state, wherein the vibration data includes vibration intensity and corresponding time. Within the entire time domain of the vibration data, multiple sub-time regions are divided, and the vibration data in each sub-time region are converted by time-frequency to obtain the vibration spectrum corresponding to each sub-time region, wherein the vibration spectrum includes vibration power corresponding to different frequencies; In the high-frequency region, the vibration spectrum of each vibration is integrally obtained to obtain the signal intensity and the sub-time region and frequency band corresponding to the signal intensity until the number of repetitions reaches the second threshold. When the signal strength is greater than a preset threshold, the sub-time region and frequency band corresponding to the signal strength are designated as high-frequency background noise regions, including: The portion in which both the sub-time region and the frequency band are the same is defined as the overlapping region, and the portion in which at least one of the sub-time regions and the frequency band are different is defined as the non-overlapping region. Within the overlapping region, the average signal strength is calculated. When the average value is greater than a preset threshold, the overlapping region is designated as a high-frequency background noise region. Within the non-overlapping region, when the signal strength is greater than the preset threshold, the non-overlapping region is designated as a high-frequency background noise region.

9. The calibration method according to claim 1, characterized in that, After defining the sub-time region and frequency band corresponding to the signal strength as a high-frequency background noise region, the calibration method further includes: The operating conditions of the engine are changed, and the process of controlling the engine to reduce the ignition advance angle and acquiring vibration data in the time domain within a single cycle is repeated when the engine is in a knock state. The vibration data includes vibration intensity and corresponding time. Within the entire time domain of the vibration data, multiple sub-time regions are divided, and the vibration data in each sub-time region are converted by time-frequency to obtain the vibration spectrum corresponding to each sub-time region, wherein the vibration spectrum includes vibration power corresponding to different frequencies; By performing a definite integral on each of the vibration spectra in the high-frequency region, the signal intensity and the sub-time region and frequency band corresponding to the signal intensity are obtained; When the signal strength is greater than a preset threshold, the sub-time region and frequency band corresponding to the signal strength are calibrated as a high-frequency background noise region until all the conditions that need to be calibrated are marked. The marked high-frequency background noise regions under each of the aforementioned operating conditions are summarized.

10. An engine calibration system, characterized in that, The calibration system is used to perform the calibration method according to any one of claims 1 to 9, and the calibration system comprises: The processing module is used to control the engine to reduce the ignition advance angle, and the acquisition module is used to acquire vibration data in the time domain within a single cycle. The processing module is further configured to divide the vibration data into multiple sub-time regions within the entire time domain, and perform time-frequency conversion on the vibration data in each sub-time region to obtain the vibration spectrum corresponding to each sub-time region. The processing module is further configured to perform definite integration on each of the vibration spectra in the high-frequency region to obtain the signal intensity and the sub-time region and frequency band corresponding to the signal intensity; The processing module is further configured to, when the signal strength is greater than a preset threshold, label the sub-time region and frequency band corresponding to the signal strength as a high-frequency background noise region.

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