A method, system and device for measuring flow rate of a fuel injector

Abstract

The present application relates to the field of intelligent sensor technology, and specifically to a method, system and device for measuring the flow rate of a fuel injector, the method comprising: determining the pressure fluctuation index of the fuel; determining the pressure vibration interference index of the fuel according to the pressure fluctuation index of the fuel, in combination with the change of all vibration data of the fuel, the discrete degree of all vibration peaks and the discrete degree of differences between all adjacent vibration peaks; determining the pressure noise content index of the fuel according to the distribution of all singular values ​​of the fuel and the pressure vibration interference index, so as to measure the flow rate of the fuel injector. The present application realizes accurate filtering of the pressure data by analyzing the degree of noise interference of the pressure data and adaptively adjusting the filter window, thereby improving the accuracy of measuring the fuel injection amount.

Description

Technical Field

[0001] The present application relates to the technical field of intelligent sensors, and in particular to a flow measurement method, system and device for a fuel injector. Background Art

[0002] With the continuous improvement of industrial automation level and the implementation of energy-saving and emission reduction policies, the requirements for engine combustion efficiency are increasing. As one of the key components of the fuel injection system, if the amount of fuel injected through the injector is too large and the fuel combustion is incomplete, the exhaust gas of the fuel vehicle will be darker in color, and in severe cases, particulate matter will be discharged, and the effect of energy conservation and emission reduction will be poor; if the amount of fuel injected is too small, the fuel combustion is incomplete, and the fuel vehicle has weak acceleration. In severe cases, it will fail to start or stall, resulting in poor power. Therefore, it is very important to accurately measure the injection flow through the injector. Accurate injection flow measurement can optimize the injection strategy, reduce harmful gas emissions, and improve fuel utilization.

[0003] The Zeuch (constant volume) method is a method for measuring the injection flow rate based on the compressibility of fuel. The injector is fixed to a container of a fixed solvent, and the injection amount is measured by the elastic modulus of the fuel and the measured pressure change. The Zeuch method is simple, easy to use, highly accurate, and stable, and can perform continuous measurements of multiple injection pulses. Therefore, it is widely used in the field of injection flow measurement. However, when the existing method measures the injection flow rate using the Zeuch method, although it takes into account that the pressure signal will be affected by high-frequency noise, it does not deeply analyze the degree of interference with the pressure signal, and thus uses a fixed filter window to filter the pressure signal, resulting in poor filtering effect and reduced accuracy in measuring the fuel injection amount. Summary of the invention

[0004] In a first aspect, an embodiment of the present application provides a method for measuring flow rate of a fuel injector, the method comprising the following steps:

[0005] Collect the pressure data and vibration data of the fuel at all the collection moments from the start to the end of the injection of the injector;

[0006] Obtain all pressure peaks and pressure valleys in all pressure data of the fuel, and determine the pressure fluctuation index of the fuel according to the mutation degree and distribution of all pressure data of the fuel and the difference between the change trend of all pressure peaks and the change trend of all pressure valleys;

[0007] Obtain all vibration peak values ​​of all vibration data of the fuel, and determine the pressure vibration interference index of the fuel according to the pressure fluctuation index of the fuel, combined with the change of all vibration data of the fuel, the discrete degree of all vibration peak values ​​and the discrete degree of differences between all adjacent vibration peak values;

[0008] The Hankel matrix constructed by obtaining all the pressure data of the fuel is subjected to singular value decomposition to obtain all the singular values ​​of the fuel; according to the distribution of all the singular values ​​of the fuel and the pressure vibration interference index, the pressure noise content index of the fuel is determined to measure the flow rate of the fuel injector.

[0009] Preferably, the method for determining the fuel pressure fluctuation index is:

[0010] Determine the difference between the slope of the straight line obtained after fitting all the pressure peak values ​​of the fuel and the slope of the straight line obtained after fitting all the pressure valley values, and record it as the first difference of the fuel;

[0011] Fitting all the pressure data of the fuel to obtain a pressure fitting straight line of the fuel, determining the discrete degree of the distance from all the pressure data of the fuel to its pressure fitting straight line, and recording it as the first discrete degree of the fuel;

[0012] All the fuel pressure data are used as the input of the sliding t-test algorithm to obtain the p value of all the fuel pressure data;

[0013] The pressure fluctuation index of the fuel is determined based on the first discrete degree and the first difference in combination with the average distribution of the p values ​​of all the pressure data of the fuel.

[0014] Preferably, the fuel pressure fluctuation index is the result of multiplying the sum of the first discrete degree and the first difference of the fuel by the mean of the p values ​​of all the pressure data.

[0015] Preferably, the method for determining the fuel pressure vibration interference index is:

[0016] All vibration data of the fuel are used as input of the KPSS test algorithm to obtain the p-value of the fuel;

[0017] Analyze the discrete degree of the difference between all adjacent vibration peaks of the fuel, and record it as the second discrete degree of the fuel;

[0018] Determining a vibration stability index of the fuel based on the discreteness of all vibration peaks of the fuel in combination with the p-value and the second discreteness;

[0019] The fuel pressure vibration interference index is the ratio of the fuel pressure fluctuation index to the vibration stability index.

[0020] Preferably, the vibration stability index of the fuel is expressed as: In the formula, E represents the vibration stability index of the fuel; P represents the p-value of the fuel; F represents the discreteness of all vibration peaks of the fuel; G represents the second discreteness of the fuel; and τ is a preset constant greater than 0.

[0021] Preferably, the method for determining the pressure noise content index of the fuel is:

[0022] All singular values ​​of fuel are clustered to obtain multiple clusters, and the mean of all singular values ​​in each cluster is calculated respectively. The cluster with the largest mean is recorded as a high singular value cluster, and the cluster with the smallest mean is recorded as a low singular value cluster.

[0023] The expression of the pressure noise content index of fuel is: Wherein, H is the pressure noise content index of the fuel; Z is the pressure vibration interference index of the fuel; K represents the difference between the mean of all singular values ​​in the high singular value cluster of the fuel and the mean of all singular values ​​in the low singular value cluster; L represents the proportion of all singular values ​​in the low singular value cluster of the fuel to all singular values ​​of the fuel; R is the mean of all singular values ​​in the low singular value cluster of the fuel; S is the range of all singular values ​​in the low singular value cluster of the fuel; σ represents a preset constant greater than 0.

[0024] Preferably, the process of measuring the flow rate of the fuel injector is:

[0025] Determining an adaptive window size of a moving average filter based on a noise content index of the fuel;

[0026] All the fuel pressure data are used as the input of the moving average filter to obtain all the filtered pressure data;

[0027] The absolute value of the difference between the pressure data at each adjacent sampling time after filtering is taken as the pressure change of the fuel at each adjacent sampling time;

[0028] The ratio of the product of the pressure change of the fuel at each adjacent sampling time and the volume of the container to the elastic modulus of the fuel at the corresponding adjacent sampling time is recorded as the volume change of the fuel;

[0029] The flow rate of the fuel at each adjacent sampling time is the ratio of the volume change of the fuel at each adjacent sampling time to the volume change at the corresponding adjacent sampling time.

[0030] Preferably, the expression of the adaptive window of the moving average filter is: T=round(α-β×exp(-H)); wherein round() is a rounding function; exp() represents an exponential function with a natural constant as the base; H represents the pressure noise content index of the fuel; α and β are preset values.

[0031] In a second aspect, an embodiment of the present application provides a flow measurement system for a fuel injector, the system comprising:

[0032] The fuel data collection module collects the pressure data and vibration data of the fuel at all collection moments from the start to the end of the injection of the injector;

[0033] The fuel data analysis module obtains all pressure peaks and pressure valleys in all pressure data of the fuel, and determines the fuel pressure fluctuation index according to the mutation degree and distribution of all pressure data of the fuel, and the difference between the change trend of all pressure peaks and the change trend of all pressure valleys;

[0034] Obtain all vibration peak values ​​of all vibration data of the fuel, and determine the pressure vibration interference index of the fuel according to the pressure fluctuation index of the fuel, combined with the change of all vibration data of the fuel, the discrete degree of all vibration peak values ​​and the discrete degree of differences between all adjacent vibration peak values;

[0035] The fuel flow measurement module obtains the Hankel matrix constructed by all the pressure data of the fuel and performs singular value decomposition on it to obtain all the singular values ​​of the fuel; according to the distribution of all the singular values ​​of the fuel and the pressure vibration interference index, the pressure noise content index of the fuel is determined to measure the flow of the fuel injector.

[0036] In a third aspect, an embodiment of the present application further provides a flow measurement device for a fuel injector, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the above-mentioned methods for measuring the flow of a fuel injector are implemented.

[0037] It can be seen from the above embodiments that the flow measurement method of a fuel injector provided in the embodiments of the present application has at least the following beneficial effects:

[0038] The present application analyzes the pressure characteristics in the container during fuel injection, determines the pressure fluctuation index of the fuel according to the mutation degree and distribution of all pressure data of the fuel, and the difference between the change trend of all pressure peaks and the change trend of all pressure valleys, so as to evaluate the mutation degree of the pressure data when rising; by analyzing the vibration degree of the container during fuel injection, based on the pressure fluctuation index of the fuel, combined with the change of all vibration data of the fuel, the discrete degree of all vibration peaks and the discrete degree of the difference between all adjacent vibration peaks, determines the pressure vibration interference index of the fuel, so as to evaluate whether abnormal vibration of the container occurs during fuel injection and whether it affects the collected pressure data; finally, constructs a feature matrix based on the pressure data and performs singular value decomposition, determines the pressure noise content index of the fuel according to the distribution of all singular values ​​of the fuel and the pressure vibration interference index, so as to analyze the influence of the noise components inside the pressure data and comprehensively evaluate the degree to which the pressure sequence is affected by high-frequency noise.

[0039] This application takes into account that the data collected by the pressure sensor during fuel injection will be affected by the vibration of the container. By deeply analyzing the degree of noise interference on the pressure data, the filter window is adaptively adjusted to achieve accurate filtering of the pressure data, thereby improving the measurement accuracy of the fuel injection amount. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A flow chart of the steps of a method for measuring flow of a fuel injector provided in one embodiment of the present application;

[0042] Figure 2 The pressure fitting straight line, pressure peak fitting straight line set and pressure valley fitting straight line effect diagram provided in this application;

[0043] Figure 3 A schematic diagram of the pressure vibration interference index extraction process provided in this application;

[0044] Figure 4 A comparison chart of the filtering effects provided for this application;

[0045] Figure 5 Schematic diagram of the injector flow rate test process provided for this application;

[0046] Figure 6 A block diagram of a flow measurement system for a fuel injector provided in accordance with an embodiment of the present application. DETAILED DESCRIPTION

[0047] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the flow measurement method, system and device of a fuel injector proposed in the present application, its specific implementation method, structure, features and effects are described in detail as follows in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0048] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0049] The specific scheme of a flow measurement method, system and device for a fuel injector provided by the present application is described in detail below with reference to the accompanying drawings.

[0050] See also Figure 1 , which shows a flow chart of a method for measuring flow of a fuel injector provided by an embodiment of the present application, the method comprising the following steps:

[0051] Step S1: Collecting the pressure data and vibration data of the fuel from the start to the end of the injection of the fuel injector.

[0052] The measurement process of the Zeuch method is as follows: fix the injector to a rigid container of fixed volume, fill the container with fuel and seal it. When measuring the injection amount, the fuel is instantly sprayed into the container through the injector nozzle. The pressure in the container will increase proportionally with the increase of the total amount of injection. Therefore, the amount of injected fuel can be deduced from the elastic modulus of the injected fuel and the pressure change of the fixed volume cavity in the container measured by the sensor, thus realizing the measurement of the fuel amount.

[0053] The injected fuel flow is measured by a high-pressure common rail injector test bench, and the inner diameter of the constant volume chamber of the container is d; during the measurement process, the rail pressure is P1, the constant volume chamber back pressure is P2, and the injection pulse width is T.

[0054] It should be noted that the value of the inner diameter d of the constant volume chamber of the container, the values ​​of the rail pressure P1 and the constant volume chamber back pressure P2, and the value of the injection pulse width are all set manually. In this embodiment, the value of the inner diameter d of the constant volume chamber of the container is 40mm, the value of the rail pressure P1 is 60MPa, the value of the constant volume chamber back pressure P2 is 3MPa, and the value of the injection pulse width T is 2ms. The implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0055] A pressure sensor is placed at a preset distance from the injector position to obtain pressure data of the fuel in the container, and a vibration acceleration sensor is placed at any position on the bottom of the container to obtain vibration data of the fuel in the container.

[0056] It should be noted that the value of the preset distance is artificially set. In this embodiment, the value of the preset distance is 37 mm. The implementer needs to set it by himself in combination with the inner diameter of the constant volume cavity of the container. This embodiment does not impose any special restrictions.

[0057] The pressure data and vibration data of the fuel inside the container are collected from the start to the end of injection of the injector, and the number of collections is set to D. At the same time, in order to eliminate the dimensions between each sequence, all pressure data and all vibration data are normalized respectively.

[0058] It should be understood that the value of the collection quantity D is artificially set. In this embodiment, the value of the collection quantity D is 600. The implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0059] It should be noted that there are many commonly used normalization methods. In this embodiment, Z-score normalization is used to normalize the pressure data and vibration data. The implementer can also choose other normalization methods such as maximum and minimum value normalization according to the specific situation. This embodiment does not impose any special restrictions.

[0060] Among them, Z-score normalization is a well-known technology, and the process of data normalization processing is not repeated here.

[0061] Step S2: Determine the fuel pressure fluctuation index according to the mutation degree and distribution of all fuel pressure data and the difference between the change trend of all pressure peak values ​​and the change trend of all pressure valley values.

[0062] During the flow measurement process of the injector, the hydraulic impact of the injector, the mechanical vibration of the injector and the fuel supply system, and the vibration of the test container will cause a lot of high-frequency noise to be mixed in the pressure data collected by the pressure sensor, so the pressure data needs to be filtered.

[0063] Since the container is already filled with fuel in the Zeuch detection method, the pressure inside the container will gradually increase when the fuel is injected into the container through the fuel injector. If the pressure sensor is less disturbed when the fuel injector injects fuel, the pressure data will rise relatively smoothly in the pressure sequence with less fluctuation; if the degree of interference is greater, the pressure data will increase more dramatically, with greater fluctuations, and many peaks will appear.

[0064] All pressure peaks and pressure valleys in all fuel pressure data are obtained through the peak and valley detection algorithm.

[0065] The stability of the fuel injection of the injector is crucial to the performance of the injection system. Unstable pressure fluctuations may lead to inaccurate injection volume, which in turn affects the performance and emissions of the engine. Therefore, based on the mutation degree and distribution of all fuel pressure data, as well as the difference between the change trend of all pressure peaks and the change trend of all pressure valleys, the fuel pressure fluctuation index is determined to identify external interference to the injector, fuel supply system or test container, specifically:

[0066] (1) Fitting all the pressure data, all the pressure peaks, and all the pressure valleys of the fuel respectively to obtain the pressure fitting straight line, the pressure peak fitting straight line, and the pressure valley fitting straight line of the fuel.

[0067] It should be noted that there are many commonly used straight line fitting methods. In this embodiment, the least squares method is used to fit all pressure data, all pressure peaks and all pressure valleys. The implementer can also use other straight line fitting methods such as linear regression to fit the corresponding data. This embodiment does not impose any special restrictions.

[0068] Among them, the least square method is a well-known technology, and the specific process of fitting the data to obtain the fitting line will not be repeated here.

[0069] Preferably, the pressure fitting straight line, pressure peak fitting straight line and pressure valley fitting straight line effect diagram provided in the present application are as follows: Figure 2 As shown in the figure, n1 represents the pressure fitting line, n2 represents the pressure peak fitting line, n3 represents the pressure valley fitting line, y1 represents the pressure data, y2 represents the pressure peak value, and y3 represents the pressure valley value.

[0070] (2) Further, the difference between the slope of the fuel pressure peak fitting line and the slope of the fuel pressure valley fitting line is determined and recorded as the first difference of the fuel.

[0071] It should be noted that there are many methods for measuring the difference. In this embodiment, the absolute value of the difference between the slope of the fitted straight line of the fuel pressure peak value and the slope of the fitted straight line of the pressure valley value is taken as a method to measure the difference between the changing trend of the pressure peak value and the changing trend of the pressure valley value. The implementer may also use other methods such as ratios to measure the difference, and this embodiment does not impose any special restrictions.

[0072] (3) Further, the discrete degree of the distance from all the pressure data of the fuel to its pressure fitting straight line is determined, which is recorded as the first discrete degree of the fuel.

[0073] It should be noted that there are many methods for measuring the degree of dispersion. In this embodiment, variance is used to measure the degree of dispersion in all cases involving the analysis of the degree of dispersion. The implementer may also use other methods for measuring the degree of dispersion, such as standard deviation or mean deviation, and this embodiment does not impose any special restrictions.

[0074] (4) Furthermore, all the fuel pressure data are used as the input of the sliding t-test algorithm to obtain the p value of all the fuel pressure data.

[0075] Among them, the sliding t-test algorithm is a well-known technology in the field of mutation point detection, and its specific process of detecting data abnormalities will not be repeated.

[0076] (5) Furthermore, the fuel pressure fluctuation index is the result of multiplying the sum of the first discrete degree and the first difference of the fuel by the mean of the p values ​​of all the pressure data.

[0077] If the first discrete degree of the fuel is smaller, it means that the distance between each pressure data and the pressure fitting straight line in all the pressure data is more consistent, that is, the fluctuation when the pressure data increases is more consistent; if the first difference of the fuel is smaller, it means that the slope of the pressure peak fitting straight line and the pressure valley fitting straight line are more consistent, that is, in the process of overall increase of the pressure peak value and the pressure valley value, the rising trend of the pressure peak value and the rising trend of the pressure valley value are relatively consistent, indicating that the degree of interference to the pressure data has been relatively stable; if the mean value of the p value of all the pressure data is smaller, the values ​​of the first difference and the first discrete degree are smaller, then the pressure fluctuation index A is smaller, indicating that the degree to which all the pressure data are disturbed by vibration high-frequency noise is smaller; conversely, if the first difference of the fuel is larger, the first discrete degree is larger, and the mean value of the p value is larger, then the pressure fluctuation index of the fuel is larger, indicating that the pressure data is more disturbed by vibration high-frequency noise.

[0078] Step S3: According to the pressure fluctuation index of the fuel, combined with the change of all vibration data of the fuel, the discreteness of all vibration peaks and the discreteness of the differences between all adjacent vibration peaks, the pressure vibration interference index of the fuel is determined.

[0079] When measuring the injection flow of the injector, the test container will be fixed in order to better measure the pressure signal of the container. If the fixing effect is very good, the test container will not vibrate when the fuel is injected, and the pressure signal collected by the pressure sensor will not generate noise due to the vibration of the container; if the fixing effect is not good, the test container will vibrate greatly when the fuel is injected, which will have a greater impact on the pressure signal collected by the pressure sensor, causing more high-frequency noise in the pressure signal, thereby affecting the measurement accuracy of the injected fuel flow.

[0080] Therefore, the peak detection algorithm is used to obtain the vibration peak value in all vibration data of the fuel. Based on the change of all vibration data of the fuel, the discrete degree of all vibration peak values ​​and the discrete degree of differences between all adjacent vibration peak values, the vibration stability index of the fuel is determined to reflect the interference degree of vibration data on pressure data. Specifically:

[0081] (1) Analyze the discrete degree of the difference between all adjacent vibration peaks of the fuel, which is recorded as the second discrete degree of the fuel.

[0082] It should be noted that there are many ways to measure the difference. In this embodiment, the absolute value of the difference between adjacent vibration peaks is taken to measure the difference between adjacent vibration peaks of the fuel. The implementer may also use ratios and other methods to measure the difference based on the specific situation. This embodiment does not impose any special restrictions.

[0083] (2) Furthermore, all vibration data of the fuel are used as the input of the KPSS (Kwiatkowski-Phillips-Schmidt-Shin) test algorithm, and the p-value of the fuel is output. The larger the p-value, the greater the stability of the vibration data.

[0084] Among them, the KPSS test algorithm is a well-known technology, and the specific process of testing the stability of data will not be repeated here.

[0085] (3) Further, the discrete degree of the difference between all adjacent vibration peaks of the fuel is analyzed and recorded as the second discrete degree of the fuel.

[0086] (4) The expression of the vibration stability index of fuel is: In the formula, E represents the vibration stability index of the fuel; F represents the discreteness of all vibration peak values ​​of the fuel; G represents the second discreteness of the fuel; τ is a preset constant greater than 0, wherein the value of τ is artificially set. In this embodiment, in order to avoid the denominator being 0 and not affecting the calculation result of the vibration stability index of the fuel due to τ, the value of τ in this embodiment is 0.01, and the implementer can also set it by himself, and this embodiment does not impose any special restrictions.

[0087] If the p-value is larger, the vibration data is more stable; if the discrete degree of all vibration peaks is smaller, the fluctuation degree of the vibration data is more consistent; if the second discrete degree G is smaller, the intervals between different peaks are more consistent, indicating that the fluctuation of the vibration sequence is stable; if the p-value is larger, the second discrete degree is smaller, and the discrete degree of the vibration peak is smaller, then the vibration stability index of the fuel is larger, indicating that the vibration data has a higher degree of stability, indicating that the test container has not undergone abnormal vibration, and the pressure signal is less disturbed by high-frequency noise; conversely, if the p-value is smaller, the second discrete degree is larger, and the discrete degree of the vibration peak is larger, then the vibration stability index of the fuel is smaller, indicating that the vibration data is more unstable, that is, the test container has undergone abnormal vibration.

[0088] Further, based on the pressure fluctuation index and the stability index, the pressure vibration interference index of the fuel is determined, specifically:

[0089] The fuel pressure vibration interference index is the ratio of the fuel pressure fluctuation index to the vibration stability index.

[0090] If the vibration stability index is smaller, it means that the possibility of abnormal vibration in the test container is greater, and the possibility of abnormal fluctuation in pressure data is greater. The larger the pressure fluctuation index, the larger the pressure vibration interference index, which means that the degree of interference to the pressure data is greater. Conversely, if the vibration stability index is larger, it means that the possibility of abnormal vibration in the test container is smaller, and the possibility of abnormal fluctuation in pressure data is smaller. The smaller the pressure vibration interference index, the smaller the degree of interference to the pressure data.

[0091] Preferably, the schematic diagram of the pressure vibration interference index extraction process provided in the present application is as follows: Figure 3 shown.

[0092] Step S4: Obtain the Hankel matrix constructed by all the pressure data of the fuel and perform singular value decomposition on it to obtain all singular values ​​of the fuel; determine the pressure noise content index of the fuel according to the distribution of all singular values ​​of the fuel and the pressure vibration interference index.

[0093] In order to determine whether the injector is disturbed by external vibration during the injection process, the useful components in the pressure data are separated from the noise through singular value decomposition and cluster analysis. Therefore, based on the distribution of all singular values ​​of the fuel and the pressure vibration interference index, the pressure noise content index of the fuel is determined to identify which singular values ​​are related to vibration high-frequency noise and eliminate the interference of vibration high-frequency noise. Specifically:

[0094] All the pressure data of the fuel are constructed as the Hankel matrix of the fuel to analyze the distribution of useful components and noise in the pressure data.

[0095] Furthermore, the Hankel matrix of the fuel is subjected to singular value decomposition to obtain all singular values ​​of the fuel.

[0096] All singular values ​​of fuel are used as inputs of the clustering algorithm to obtain multiple clusters. Further, the means of all singular values ​​in the two clusters are calculated respectively, and the cluster with the largest mean is recorded as the high singular value cluster, and the cluster with the smallest mean is recorded as the low singular value cluster.

[0097] The expression of the pressure noise content index of fuel is: Wherein, H is the pressure noise content index of the fuel; Z is the pressure vibration interference index of the fuel; K represents the difference between the mean of all singular values ​​in the high singular value cluster of the fuel and the mean of all singular values ​​in the low singular value cluster; L represents the proportion of the number of all singular values ​​in the low singular value cluster of the fuel in all singular values ​​of the fuel; R is the mean of all singular values ​​in the low singular value cluster of the fuel; S is the range of all singular values ​​in the low singular value cluster of the fuel; σ represents a preset constant greater than 0, and the value of σ is set artificially. In this embodiment, in order to avoid the denominator being 0 and not affecting the calculation result of the vibration stability index of the fuel due to τ, σ is taken as 0.01 in this embodiment, and the implementer can also set it by himself. This embodiment does not impose any special restrictions.

[0098] It should be noted that there are many methods for measuring differences. In this embodiment, the absolute value of the difference between the mean of all singular values ​​in the high singular value cluster of the fuel and the mean of all singular values ​​in the low singular value cluster is taken to measure the difference between clusters. The implementer may also use other methods for measuring differences such as ratios, and this embodiment does not impose any special restrictions.

[0099] If the difference between the mean of all singular values ​​in the high singular value cluster of the fuel and the mean of all singular values ​​in the low singular value cluster is greater, it means that the pressure data is more disturbed; if the proportion of low singular values ​​is larger, it means that the pressure data is more disturbed; if the mean of all singular values ​​in the low singular value cluster is smaller, the possibility of the singular value corresponding to the noise is greater; if the range is smaller, it means that the fluctuation of the singular value is smaller, and it is more consistent with the singular value characteristics corresponding to the noise. Therefore, if the pressure noise content index is larger, it means that the pressure signal collected by the pressure sensor when the injector is spraying fuel is more affected by high-frequency noise.

[0100] Step S5: based on the pressure noise content index of the fuel, all the pressure data of the fuel are subjected to noise reduction.

[0101] The denoising effect of the moving average filter depends on the selection of the filter window size. A larger window can better smooth the signal and remove noise, while a smaller window can better preserve the details of the signal.

[0102] Therefore, the larger the calculated pressure noise content index of the fuel, the larger the filter window needs to be.

[0103] The expression of the window of the moving average filter is: T = round(α-β×exp(-H)); wherein round() is a rounding function; exp() represents an exponential function with a natural constant as the base; T represents the adaptive window of the moving average filter; H represents the pressure noise content index of the fuel; α and β are preset values.

[0104] It should be understood that the values ​​of α and β are artificially set. In this embodiment, the value of α is 45 and the value of β is 11. The implementer can set them according to the specific filter performance requirements, and this embodiment does not impose any special restrictions.

[0105] It should be noted that in order to ensure that the core element of the filter is located at the center and the weights on both sides are symmetrically distributed, the window size is processed. If the calculation result is an odd number, T is used as the window size, and all the pressure data of the fuel are input into the moving average filter to obtain all the pressure data after filtering; if the calculation result is an even number, T-1 is used as the window size, and all the pressure data of the fuel are passed through the moving average filter to obtain all the pressure data after filtering.

[0106] The absolute value of the difference between the pressure data at each adjacent sampling time after filtering is taken as the pressure change of the fuel at each adjacent sampling time;

[0107] The ratio of the product of the pressure change of the fuel at each adjacent sampling time and the volume of the container to the elastic modulus of the fuel at the corresponding adjacent sampling time is recorded as the volume change of the fuel;

[0108] The flow rate of the fuel at each adjacent sampling time is the ratio of the volume change of the fuel at each adjacent sampling time to the volume change at the corresponding adjacent sampling time.

[0109] The calculation process of the elastic modulus of the fuel at each adjacent sampling time is a well-known technology, and the specific process will not be repeated here.

[0110] Preferably, the schematic diagram of the injector flow rate test process provided in the present application is as follows: Figure 4 shown.

[0111] At this point, the filtering effect of the filter is improved based on the pressure noise content index of the fuel, and the measurement of the fuel injection flow is completed.

[0112] Preferably, the schematic diagram of the injector flow rate test process provided in the present application is as follows: Figure 5 shown.

[0113] Based on the same inventive concept as the above method, the embodiment of the present application further provides a flow measurement system for a fuel injector, comprising:

[0114] The fuel data collection module collects the pressure data and vibration data of the fuel at all collection moments from the start to the end of the injection of the injector;

[0115] The fuel data analysis module obtains all pressure peaks and pressure valleys in all pressure data of the fuel, and determines the fuel pressure fluctuation index according to the mutation degree and distribution of all pressure data of the fuel, and the difference between the change trend of all pressure peaks and the change trend of all pressure valleys;

[0116] Obtain all vibration peak values ​​of all vibration data of the fuel, and determine the pressure vibration interference index of the fuel according to the pressure fluctuation index of the fuel, combined with the change of all vibration data of the fuel, the discrete degree of all vibration peak values ​​and the discrete degree of differences between all adjacent vibration peak values;

[0117] The fuel flow measurement module obtains the Hankel matrix constructed by all the pressure data of the fuel and performs singular value decomposition on it to obtain all the singular values ​​of the fuel; according to the distribution of all the singular values ​​of the fuel and the pressure vibration interference index, the pressure noise content index of the fuel is determined to measure the flow of the fuel injector.

[0118] The flow measurement system block diagram of a fuel injector provided in an embodiment of the present application is as follows: Figure 6 shown.

[0119] Based on the same inventive concept as the above method, an embodiment of the present application also provides a flow measurement device for a fuel injector, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the above-mentioned flow measurement methods for a fuel injector are implemented.

[0120] It should be noted that the above sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above is a description of a specific embodiment of this specification. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0121] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0122] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for measuring the flow rate of a fuel injector, characterized in that: The method comprises the following steps: Collect the pressure data and vibration data of the fuel at all the collection moments from the start to the end of the injection of the injector; Obtain all pressure peaks and pressure valleys in all pressure data of the fuel, and determine the pressure fluctuation index of the fuel according to the mutation degree and distribution of all pressure data of the fuel and the difference between the change trend of all pressure peaks and the change trend of all pressure valleys; Obtain all vibration peak values ​​of all vibration data of the fuel, and determine the pressure vibration interference index of the fuel according to the pressure fluctuation index of the fuel, combined with the change of all vibration data of the fuel, the discrete degree of all vibration peak values ​​and the discrete degree of differences between all adjacent vibration peak values; Obtaining a Hankel matrix constructed from all the pressure data of the fuel and performing singular value decomposition on the matrix to obtain all singular values ​​of the fuel; determining a pressure noise content index of the fuel according to the distribution of all the singular values ​​of the fuel and the pressure vibration interference index to measure the flow rate of the fuel injector; The process of measuring the flow rate of the fuel injector is as follows: Determining an adaptive window size of a moving average filter based on a noise content index of the fuel; All the pressure data of the fuel are used as the input of the moving average filter to obtain all the pressure data after filtering; The absolute value of the difference between the pressure data at each adjacent sampling time after filtering is taken as the pressure change of the fuel at each adjacent sampling time; The ratio of the product of the pressure change of the fuel at each adjacent sampling time and the volume of the container to the elastic modulus of the fuel at the corresponding adjacent sampling time is recorded as the volume change of the fuel; The flow rate of the fuel at each adjacent sampling time is the ratio of the volume change of the fuel at each adjacent sampling time to the volume change at the corresponding adjacent sampling time.

2. A method for measuring the flow rate of a fuel injector as claimed in claim 1, characterized in that: The method for determining the pressure fluctuation index of the fuel is: Determine the difference between the slope of the straight line obtained after fitting all the pressure peak values ​​of the fuel and the slope of the straight line obtained after fitting all the pressure valley values, and record it as the first difference of the fuel; Fitting all the pressure data of the fuel to obtain a pressure fitting straight line of the fuel, determining the discrete degree of the distance from all the pressure data of the fuel to its pressure fitting straight line, and recording it as the first discrete degree of the fuel; All the fuel pressure data are used as the input of the sliding t-test algorithm to obtain the p value of all the fuel pressure data; The pressure fluctuation index of the fuel is determined based on the first discrete degree and the first difference in combination with the average distribution of the p values ​​of all the pressure data of the fuel.

3. A method for measuring the flow rate of a fuel injector as claimed in claim 2, characterized in that: The fuel pressure fluctuation index is a result of multiplying the sum of the first discrete degree and the first difference of the fuel by the mean of the p values ​​of all the pressure data.

4. A method for measuring the flow rate of a fuel injector as claimed in claim 1, characterized in that: The method for determining the pressure vibration interference index of the fuel is as follows: All vibration data of the fuel are used as input of the KPSS test algorithm to obtain the p-value of the fuel; Analyze the discrete degree of the difference between all adjacent vibration peaks of the fuel, and record it as the second discrete degree of the fuel; Determining a vibration stability index of the fuel based on the discreteness of all vibration peaks of the fuel in combination with the p-value and the second discreteness; The fuel pressure vibration interference index is the ratio of the fuel pressure fluctuation index to the vibration stability index.

5. A method for measuring the flow rate of a fuel injector as claimed in claim 4, characterized in that: The expression of the vibration stability index of the fuel is: In the formula, E represents the vibration stability index of the fuel; P represents the p-value of the fuel; F represents the discreteness of all vibration peaks of the fuel; G represents the second discreteness of the fuel; and τ is a preset constant greater than 0.

6. A method for measuring the flow rate of a fuel injector as claimed in claim 1, characterized in that: The method for determining the pressure noise content index of the fuel is: All singular values ​​of fuel are clustered to obtain multiple clusters, and the mean of all singular values ​​in each cluster is calculated respectively. The cluster with the largest mean is recorded as a high singular value cluster, and the cluster with the smallest mean is recorded as a low singular value cluster. The expression of the pressure noise content index of fuel is: Wherein, H is the pressure noise content index of the fuel; Z is the pressure vibration interference index of the fuel; K represents the difference between the mean of all singular values ​​in the high singular value cluster of the fuel and the mean of all singular values ​​in the low singular value cluster; L represents the proportion of the number of all singular values ​​in the low singular value cluster of the fuel to all singular values ​​of the fuel; R is the mean of all singular values ​​in the low singular value cluster of the fuel; S is the range of all singular values ​​in the low singular value cluster of the fuel; σ represents a preset constant greater than 0.

7. A method for measuring the flow rate of a fuel injector as claimed in claim 1, characterized in that: The expression of the adaptive window of the moving average filter is: T=round(α-β×exp(-H)); wherein round() is a rounding function; exp() represents an exponential function with a natural constant as the base; T represents the adaptive window of the moving average filter; H represents the pressure noise content index of the fuel; α and β are preset values.

8. A flow measurement system for a fuel injector, implementing the method as claimed in claim 1, characterized in that: The system comprises: The fuel data collection module collects the pressure data and vibration data of the fuel at all collection moments from the start to the end of the injection of the injector; The fuel data analysis module obtains all pressure peaks and pressure valleys in all pressure data of the fuel, and determines the fuel pressure fluctuation index according to the mutation degree and distribution of all pressure data of the fuel, and the difference between the change trend of all pressure peaks and the change trend of all pressure valleys; Obtain all vibration peak values ​​of all vibration data of the fuel, and determine the pressure vibration interference index of the fuel according to the pressure fluctuation index of the fuel, combined with the change of all vibration data of the fuel, the discrete degree of all vibration peak values ​​and the discrete degree of differences between all adjacent vibration peak values; The fuel flow measurement module obtains the Hankel matrix constructed by all the pressure data of the fuel and performs singular value decomposition on it to obtain all the singular values ​​of the fuel; according to the distribution of all the singular values ​​of the fuel and the pressure vibration interference index, the pressure noise content index of the fuel is determined to measure the flow of the fuel injector.

9. A flow measurement device for a fuel injector, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the flow measurement method for a fuel injector as described in any one of claims 1 to 7 are implemented.

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