Vibration-based diesel engine crankshaft running wear degree feature identification method

Abstract

The application provides a diesel engine crankshaft operation wear degree feature recognition method based on vibration, comprising the following steps: a crankshaft wear monitoring minimum vibration measuring point arrangement; and feature recognition of the crankshaft shaft system wear degree based on the minimum vibration measuring point arrangement. The application has the beneficial effects that: the monitoring evaluation index calculation complexity of the application is suitable for the current mainstream edge collection equipment, is easy to realize miniaturization to meet the matching power accompanying monitoring, and has low monitoring investment cost, facilitating the whole life cycle monitoring of high-value diesel engines; the measuring point arrangement of the application combines the characteristics of the physical structure and working parts of the diesel engine, the recognition method uses a normalized index, the monitoring limit value is not dependent on the determination of long-term statistical results, is suitable for the monitoring of the first working characteristics of new research and development heavy-duty diesel engine products, and meets the monitoring of different diesel engines under different working conditions, and the index evaluation has good transplantation ability.

Description

Technical Field

[0001] This invention belongs to the field of diesel engine technology, and in particular relates to a method for identifying the wear characteristics of diesel engine crankshafts based on vibration. Background Technology

[0002] Diesel engines still have a significant presence in special-purpose vehicles and civilian power systems. Current diesel engine research and development focuses on lightweight design, continuously enhancing power output and exploring the load-bearing potential of various structural components to achieve strong power delivery within a relatively small volume. The crankshaft friction pair is the main load-bearing unit for enhancing the output torque of a diesel engine. Severe abnormal wear on the crankshaft has a significant impact on the diesel engine, directly causing damage to the entire machine and becoming one of the factors determining the service life of a diesel engine.

[0003] The crankshaft friction pair is the main load-bearing unit for the power output torque of a diesel engine and one of the decisive factors for its durability and lifespan. This is especially true for lightweight reinforced diesel engines, which have high power per unit volume, high load per unit area on the crankshaft system, and severe wear, leading to sudden abnormal wear events. Without effective online monitoring methods, continuing to increase cylinder working pressure during development and use can push the crankshaft friction pair beyond its load-bearing limit, resulting in serious damage. This situation is the core reason for the long development cycle and high R&D cost of current reinforced diesel engines.

[0004] Specific drawbacks of existing technologies:

[0005] (1) The current diesel engine wear monitoring adopts the working lubricating oil sampling method and carries out offline detection of spectrometry, energy spectrum and ferrography. Due to the influence of sampling cycle and sampling status, it is difficult to keep up with the working status of the diesel engine in a timely manner. At the same time, the current offline sampling oil sample detection method is a comprehensive analysis tool for all friction pairs of the diesel engine. It is not strong in the localization of crankshaft friction pairs and it is difficult to locate the indicators related to the wear of crankshaft friction pairs.

[0006] (2) The current online lubricating oil abrasive monitoring method captures lubricating oil particles during diesel engine operation. It can only classify and count particles of different sizes, but cannot determine the source of abrasive particles. It is difficult to correlate with the wear degree of friction pairs. It is necessary to add lubricating oil sampling for abnormal alarm process, and offline detection by scanning electron microscopy + energy dispersive spectroscopy to determine the source of particles. It is difficult to quickly detect the wear state. At the same time, the false alarm rate is high due to the influence of gear particles.

[0007] (3) The current vibration feature construction monitoring method based on wear anomaly events has insufficient design of sensor installation positions, resulting in uncertainty in the number of sensors installed and the characteristics analyzed. This makes it difficult to form a stable and effective online wear monitoring capability. Furthermore, the existing technology uses nearby installed surface vibration sensors to collect data for identifying anomalies in the components of interest. It relies on manual feature extraction or artificial intelligence to determine the contribution of data features to the correlation with anomaly events, making it difficult to decouple the uncertainty introduced by anomalies in other working components such as cylinders and transmissions from the data. Using self-learning of monitoring features for warning assignment makes it difficult to ensure that the algorithm can be used in different operating environments (rigid, elastic suspension, and automotive installation). Summary of the Invention

[0008] In view of this, the present invention aims to propose a vibration-based method for identifying the wear characteristics of diesel engine crankshafts, in order to solve the problem that there is no equipment and method in the prior art that can directly monitor the wear of crankshaft friction pairs online without changing the working parts of the diesel engine, and that it is difficult to provide reliable and effective monitoring and early warning of abnormal wear of crankshaft friction pairs in the process of strengthening diesel engine performance calibration.

[0009] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0010] A vibration-based method for identifying the wear characteristics of diesel engine crankshafts includes the following steps:

[0011] S1. Simplified vibration measurement point layout for crankshaft wear monitoring;

[0012] S2. Based on the simplest vibration measurement point layout, feature identification of crankshaft system wear is performed.

[0013] In step S1, the simplified vibration measurement point arrangement for crankshaft wear monitoring includes:

[0014] S11. Prepare the diesel engine model and the mounting base model, import them into CAD, confirm the material properties, and adjust the origin of the diesel engine model coordinate system to the centroid.

[0015] S12. Diesel engine parameter calculation: Use CAD tools to calculate the diesel engine moment of inertia, base mounting position coordinates, base static stiffness, and base mounting angle;

[0016] S13. Based on the diesel engine parameters, assemble the calculation matrix, which includes the inertial matrix, the base distance matrix, the base stiffness matrix, and the base mounting angle matrix.

[0017] S14. Based on the base distance matrix, base stiffness matrix and base installation angle matrix, synthesize a full-rank stiffness matrix;

[0018] S15. Establish the crankshaft direction array and the shaft array;

[0019] S16. Solve for the torque axis transformation matrix based on the inertial matrix and the rotation axis matrix; solve for the elastic axis transformation matrix based on the full-rank stiffness matrix and the crankshaft direction matrix.

[0020] S17. Construct the torque axis and elastic axis based on the torque axis transformation matrix and the elastic axis transformation matrix;

[0021] S18. Construct the torque shaft projection onto the outer contour of the diesel engine, and extend the elastic shaft to the intersection with the transmission box;

[0022] S19. Determine the locations of the three measuring points.

[0023] Furthermore, in step S18, constructing the projection of the torque shaft onto the outer contour of the diesel engine and extending the elastic shaft to the intersection with the transmission box includes:

[0024] Draw a vertical plane perpendicular to the diesel engine through the elastic axis, draw the line of symmetry of the torque axis through the vertical plane, and project the torque axis to the outer contour of the diesel engine; extend the axis of the elastic axis.

[0025] Furthermore, in step S19, the locations of three measuring points are determined, including:

[0026] S191. Based on the two intersection points of the torque axis projection line and the outer contour of the diesel engine, determine the first and second measuring points; based on the intersection point of the elastic axis and the end face of the transmission box, determine the third measuring point.

[0027] S192. Based on the sensor operating temperature and the surface mounting characteristics of the diesel engine, determine whether the actual layout is met. If not, adjust the position based on the torque axis projection line.

[0028] S193. Determine the locations of the three measuring points.

[0029] Furthermore, in step S2, based on the simplest vibration measurement point arrangement, feature identification is performed on the crankshaft system wear, including:

[0030] S21. Parameter preparation: Calculate the carrier frequency range; Data acquisition: Obtain data from three measurement points.

[0031] S22. Based on the data from three measurement points, spatial response data processing is performed to obtain the response results for three degrees of freedom.

[0032] S23. Based on the carrier frequency range and degree of freedom response results, perform data preprocessing to obtain the amplitude spectrum and phase spectrum;

[0033] S24. Calculate the wear index of crankshaft friction pair based on amplitude spectrum and phase spectrum;

[0034] S25, Real-time output of crankshaft friction pair wear indicators.

[0035] Furthermore, in step S21, parameter preparation includes calculating the carrier frequency range; data acquisition involves obtaining data from three measurement points, including:

[0036] S211. Parameter preparation: Using the modal testing method or component modal calculation method, obtain the constraint mode center frequency above 1KHz of the component installed at three measurement points, and calculate the carrier frequency range.

[0037] S212. Data Acquisition: Collect parameters from three measurement points respectively, and filter them using a 5Hz high-pass filter to obtain data from measurement point one, measurement point two, and measurement point three.

[0038] Furthermore, in step S22, spatial response data processing includes:

[0039] S221. The time-domain results of measuring point one minus measuring point two characterize the overturning and vertical translation (RY, Z) degrees of freedom response results introduced by the crankshaft's revolution.

[0040] S222, the time-domain results of measuring point one minus measuring point two plus measuring point three characterize the response results of the left and right yaw and forward and backward sway (RZ, Y) degrees of freedom introduced by the crankshaft's revolution;

[0041] S223, the time-domain results of measuring point two minus measuring point three characterize the response results of the vertical pitch and horizontal lateral (RX, X) degrees of freedom introduced by the crankshaft's revolution.

[0042] Furthermore, in step S23, data preprocessing is performed to obtain the amplitude spectrum and phase spectrum, including:

[0043] S231. For the time domain results of measurement point 1 minus measurement point 2, measurement point 1 minus measurement point 2 plus measurement point 3, and measurement point 2 minus measurement point 3 in step S22, set the bandpass filter according to the carrier frequency range of step S211.

[0044] S232. Perform bandpass filtering, envelope extraction and fast Fourier transform on the response results of steps S221, S222 and S223 respectively to form amplitude spectrum two, amplitude spectrum four and amplitude spectrum six.

[0045] S233. Perform Fast Fourier Transform and Integration on the response results of steps S221, S222 and S223 respectively to form amplitude spectrum one and phase spectrum one, amplitude spectrum three and phase spectrum three, and amplitude spectrum five and phase spectrum five.

[0046] S234. Perform a fast Fourier transform on the data from measurement point 1 to generate the amplitude spectrum zero and the phase spectrum zero.

[0047] Furthermore, in step S24, the calculation of the crankshaft friction pair wear index includes:

[0048] S241. Based on the zero amplitude spectrum and zero phase spectrum obtained in step S234, perform an amplitude scan within the range of 5Hz-75Hz to obtain values ​​greater than 0.02m·s. 2 The first center frequency fr;

[0049] S242. Based on the phase within the frequency range of the first center frequency fr ± 0.5, and with the condition that |maximum phase - minimum phase| ≥ 100°, determine the virtual rotational frequency to form the working speed parameters;

[0050] S243. Construct a tuning function based on virtual frequency conversion;

[0051] S244. For amplitude spectrum two, amplitude spectrum four, and amplitude spectrum six, multiply them with the tuning function and then perform integration.

[0052] S245. For amplitude spectrum two, amplitude spectrum four and amplitude spectrum six, as well as amplitude spectrum one, amplitude spectrum three and amplitude spectrum five, the crankshaft trajectory, spatial wear rate and load rate are synchronously mapped, and then weighted and synthesized to form wear degree, wear rate and load rate indicators.

[0053] Furthermore, in step S25, the crankshaft friction pair wear index is output in real time, including:

[0054] The system provides real-time output of crankshaft friction pair load rate, wear degree, and uneven wear degree indicators at the operating speed.

[0055] Compared with existing technologies, the vibration-based diesel engine crankshaft wear characteristic identification method of the present invention has the following advantages:

[0056] (1) This invention solves the problem of real-time tracking, monitoring and evaluation of wear of crankshaft friction pairs in newly developed enhanced diesel engines. When matching new components such as fuel supply and combustion, as well as high explosion pressure and high indication characteristics, the safety margin of crankshaft friction pairs can be quickly determined to determine whether subsequent adjustment schemes can be safely implemented. At the same time, this invention can also be used for testing the working performance of in-use diesel engines, providing a safety guarantee for the working reliability of high-value diesel engines.

[0057] (2) In order to make the monitoring equipment easy to install and the diesel engine results not to be changed during installation, the present invention provides the simplest sensor arrangement method, which proposes to use the elastic working shaft and torque working shaft with the inherent characteristics of the diesel engine as the arrangement basis, and to monitor shaft system problems by arranging vibrations in symmetrical positions of the diesel engine. The introduced reverse torque response change is utilized. At the same time, in the algorithm, considering the problem of inconsistent monitoring indicators introduced by different installation methods and different road conditions, the spatial degree of freedom response difference is constructed under synchronous sensor detection to remove the in-phase results introduced by external excitation, combustion excitation and interference.

[0058] (3) In order to make the monitoring method related to the working conditions of the diesel engine and to specifically evaluate the wear characteristics of low speed light load, high speed light load and high speed high load, without installing speed and torque sensors, this invention proposes a virtual frequency determination method based on amplitude sweep frequency and phase difference determination, so that the response rate of the virtual frequency can be synchronously indicated with the wear index, which facilitates the backtracking of the working speed during the monitoring process. This invention also provides a load rate determination index, which takes the characteristics introduced by the working response and load demand of the diesel engine as the benchmark, constructs the relationship between the reaction torque and the working response, and normalizes and removes the viscous damping coefficient to form a load rate index that represents the power output of the diesel engine.

[0059] (4) In order to enhance the real-time monitoring of the wear of the crankshaft friction pair of the diesel engine, the wear degree is mapped by the constructed (RY, Z) spatial degree of freedom response. Based on the principle of equivalent rigidity of crankshaft working, the wear of the friction pair shows the decrease of the constraint of the engine body on the crankshaft revolution degree of freedom, the strengthening of the off-center load of the diesel engine components by the frequency excitation, and the significant component carrier. The relative carrier and off-center load difference frequency increment are extracted to form a normalized mapping index. The weight coefficient is constructed with the characteristics of low speed light load, high speed light load, low speed high load, and high speed high load to realize the crankshaft wear degree monitoring effect related to the working load of the diesel engine.

[0060] (5) In order to further indicate the wear characteristics of the crankshaft friction pair of lightweight and weak stiffness diesel engine, the wear index is mapped by the bending degree correlation of the crankshaft in the flexible state using the constructed (RZ, Y) spatial degree of freedom response. Based on the elliptical trajectory characteristics of the diesel engine operation process, the crankshaft is driven to bend. A normalized index is proposed to correlate the trajectory and response. The effective output of the diesel engine crankshaft and the reaction response characteristics of the load are used as the two monitoring sources to determine the relationship between the trajectory shape and the wear response amplitude. The roundness degradation is used as the maximum tolerance limit of the absolute monitoring response to achieve the monitoring effect of the wear degree of the crankshaft friction pair.

[0061] (6) The computational complexity of the monitoring and evaluation indicators provided by this invention is suitable for current mainstream edge acquisition equipment, and it is easy to achieve miniaturization to meet the requirements of power-accompanying monitoring. Moreover, the monitoring investment cost is low, which facilitates the full life cycle monitoring of high-value diesel engines. At the same time, the arrangement provided by this invention combines the characteristics of the physical structure and working parts of the diesel engine itself. The identification method uses normalized indicators, and the monitoring limit does not depend on the determination of long-term statistical results. It is suitable for monitoring the first working characteristics of newly developed enhanced diesel engine products, as well as meeting the monitoring requirements of different diesel engines under different working conditions. The indicator evaluation has good portability and can provide effective assessment guarantee for wear status for scientific research and users. Attached Figure Description

[0062] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0063] Figure 1 This is a schematic diagram of the simplified vibration measurement point arrangement process for crankshaft wear monitoring according to an embodiment of the present invention;

[0064] Figure 2 This is a schematic diagram of the crankshaft wear feature identification process based on the simplest vibration measuring point arrangement method described in an embodiment of the present invention;

[0065] Figure 3 This is a front view schematic diagram of adjusting the coordinate origin of the diesel engine model according to an embodiment of the present invention;

[0066] Figure 4 This is a top view schematic diagram of adjusting the coordinate origin of the diesel engine model according to an embodiment of the present invention;

[0067] Figure 5 This is a schematic diagram of the elastic axis and torque axis described in an embodiment of the present invention;

[0068] Figure 6 This is a schematic diagram of the torque shaft projected onto the outer contour of a V-type diesel engine according to an embodiment of the present invention;

[0069] Figure 7 This is a schematic diagram of the torque shaft projected onto the outer contour of an inline diesel engine according to an embodiment of the present invention;

[0070] Figure 8 This is a schematic diagram of the installation of the measuring points on the V-type diesel engine according to an embodiment of the present invention;

[0071] Figure 9 This is a schematic diagram of the installation of measuring points on an inline diesel engine according to an embodiment of the present invention;

[0072] Figure 10 This is a schematic diagram of virtual frequency conversion calculation according to an embodiment of the present invention;

[0073] Figure 11 This is a schematic diagram illustrating the process monitoring speed and load rate according to an embodiment of the present invention;

[0074] Figure 12 This is a partial schematic diagram of the load rate according to an embodiment of the present invention;

[0075] Figure 13 This is a schematic diagram illustrating the online calculation of wear rate under full-speed partial load as described in an embodiment of the present invention. Detailed Implementation

[0076] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0077] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0078] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0079] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0080] like Figures 1 to 13 As shown, a vibration-based method for identifying the wear characteristics of diesel engine crankshafts is presented.

[0081] like Figure 1 As shown, the simplest vibration measurement points for monitoring crankshaft wear are arranged, including the following steps:

[0082] Step 1, Model Preparation: Prepare the diesel engine model and the mounting base model, import them into CAD, confirm the integrity and correctness of the material properties, and adjust the origin of the diesel engine model coordinates to the centroid.

[0083] Step 2: Diesel engine parameter calculation: Use CAD to calculate the diesel engine moment of inertia, base mounting position coordinates, base static stiffness, and base mounting angle.

[0084] Step 3: Assemble the calculation matrices: Assemble the inertial matrix M, the base distance matrix B, the base stiffness matrix KK, and the base mounting angle matrix T;

[0085] Step 4: Synthesize the full-rank stiffness matrix: Use the base distance matrix B, the base stiffness matrix KK, and the base mounting angle matrix T to synthesize a 6x6 matrix to resolve singularities;

[0086] Step 5: Establish crankshaft direction matrix and shaft matrix: Based on the working axis and rotation direction of the diesel engine crankshaft, construct the crankshaft direction matrix f and the shaft matrix Traf, where f is of size 1X6 and Traf is of size 1X3.

[0087] Step 6: Solve for the transformation matrices of the elastic axis and the torque axis: Solve for the torque axis transformation matrix based on the assembled inertia matrix M and the rotation axis matrix Traf, and solve for the elastic axis transformation matrix based on the full-rank stiffness composite matrix and the elastic axis transformation matrix f.

[0088] Step 7: Construct the elastic axis and torque axis: Substitute the elastic axis transformation matrix and torque axis transformation matrix to solve for the four coordinate points TLS, TLE, ELS, and ELE. Connect the coordinate points in pairs to form the elastic axis and torque axis.

[0089] Step 8: Construct the projection of the torque axis onto the outer contour of the diesel engine, and extend the elastic axis to the intersection with the transmission box: Draw a vertical plane perpendicular to the diesel engine through the elastic axis, draw the line of symmetry of the torque axis through the vertical plane, and project the torque axis onto the outer contour of the diesel engine; extend the axis of the elastic axis.

[0090] Step 9: Determine the positions of the three simplest measuring points: Use the two intersection points where the projected torque axis intersects with the outer contour of the diesel engine to determine the first and second measuring points, and use the intersection point of the elastic axis and the end face of the transmission box to determine the third measuring point;

[0091] Step 10: Determine if the actual layout is met: Using factors such as sensor operating temperature and diesel engine surface mounting, check whether measuring points 1, 2, and 3 meet the installation requirements, and adjust the measuring points that do not meet the requirements according to the rules.

[0092] Step 11: Determine the locations of the three measuring points: Schematic diagram of the installation, and output the process requirements for the installation locations of the three measuring points.

[0093] The specific implementation method is as follows:

[0094] A1: Import the 3D model of the diesel engine and mounting base into CAD, check that the model unit is m.kg.s, check that the model material properties are complete, and confirm that the model mass deviates from the actual mass of the whole machine by less than 5%.

[0095] A2: Use a fully digital model of the diesel engine to solve for the coordinates of the center point of the mounting base (M1x, M1y, M1z; M2x, M2y, M2z; M3x, M3y, M3z; M4x, M4y, M4z) based on the origin of the center of mass, as well as the six moments of inertia Ix (kg·m2), Iy (kg·m2), Iz (kg·m2), Ixy (kg·m2), Iyz (kg·m2), and Ixz (kg·m2) with the center of mass at the midpoint. Use a fully digital model of the diesel engine mounting base components to add the overall machine mass to solve for the vertical and lateral static stiffness Kzz0 and Kyy0, and solve for the dynamic stiffness Kxx=1.3Kyy0, Kyy=1.3Kyy0, and Kzz=1.3Kzz0 in the three directions according to a dynamic-static stiffness ratio coefficient of 1.3.

[0096] A3: Based on the actual installation angles of the diesel engine mounting base components, assemble the installation angle matrix of i bases, Ti[cos(Aix-u), cos(Aiy-u), cos(Aiz-u); cos(Aix-v), cos(Aiy-v), cos(Aiz-v); cos(Aix-w), cos(Aiy-w), cos(Aiz-w)], (Aix-u represents the installation angle between the x-direction of the i-th base and the u-direction (xu) of the diesel engine).

[0097] Based on the coordinates of the center point of the mounting base obtained from A2, the distance matrix Bi[1, 0, 0, 0, Miz, -Miy; 0, 1, 0, -Miz, 0, Mix; 0, 0, 1, Miy, -Mix, 0] is used to assemble the diesel engine.

[0098] Based on the rotational inertia solved by A2, assemble the inertial matrix M[Jx, -Jxy, -Jxz; -Jxy, Jy, -Jyz; -Jxz, -Jyz, Jz];

[0099] Based on the dynamic stiffness obtained from A2, the stiffness matrix KKi[Kixx, 0, 0; 0, Kiyy, 0; 0, 0, Kizz] of each base of the diesel engine is assembled.

[0100] A4: Based on the base mounting angle matrix Ti, base distance matrix Bi, and base stiffness matrix KKi assembled from A3, a full-rank stiffness matrix K is synthesized, as expressed below:

[0101] ;

[0102] In the formula, For a full-rank stiffness matrix, For the base distance array, Install the corner array on the base. For the base stiffness matrix, For the number of bases, Number the base.

[0103] A5: Establish a diesel engine crankshaft orientation matrix with the crankshaft as the Y-axis and rotating clockwise when viewed from the free end. and rotating array ;

[0104] A6: Solve for the elastic axis transformation matrix 'a' introduced by the base, as expressed below:

[0105] ;

[0106] In the formula, It is an elastic axis transformation matrix. For a full-rank stiffness matrix, For crankshaft direction array;

[0107] The expression for solving the torque axis transformation matrix b introduced by the diesel engine reaction torque is as follows:

[0108] ;

[0109] In the formula, For torque axis transformation matrix, It is an inertial array. It is a rotating matrix.

[0110] A7: Based on the elastic axis transformation matrix a, solve for the coordinates of the starting point ELS and the ending point ELE of the elastic axis, where ELS is (-a(4), -a(5), -a(6)). ;

[0111] Based on the torque axis transformation matrix b, the coordinates of the inverse torque axis starting point TLS and ending point TLE are solved, where TLS is (-b(1), -b(2), -b(3)). ;

[0112] In CAD, the center of mass of the diesel engine is used as the origin, and the four coordinate points TLS, TLE, ELS and ELE of the torque axis and elastic axis are used to construct the elastic axis and torque axis.

[0113] A8: In CAD software, draw a plane perpendicular to the diesel engine through the elastic axis, draw the line of symmetry of the torque axis through the drawn vertical plane, and vertically raise the projected torque axis to the outer contour of the diesel engine; extend the elastic axis to the end face of the diesel engine transmission box.

[0114] A9: Based on the coincidence of the endpoints TLS' and TLE' of the projection torque axis with the outer contour of the diesel engine, select the first and second measuring points;

[0115] Based on the intersection of the elastic axis and the end face of the transmission box, the third measuring point is selected.

[0116] A10: Based on the sensor's operating temperature and whether the installation position is on a reliable mounting surface of the diesel engine, check whether measuring points 1, 2, and 3 meet the installation requirements. If measuring points 1 and 2 do not meet the requirements, adjust them according to the torque axis direction. If measuring point 3 does not meet the requirements, adjust it according to the vertical direction of the plane perpendicular to the torque axis.

[0117] A11: Finally, the locations of the three simplest monitoring points were determined, and the installation requirements were illustrated.

[0118] like Figure 2 As shown, based on the simplest vibration measurement point arrangement, the wear characteristics of the crankshaft system are identified, including the following steps:

[0119] Step 1, Parameter Preparation and Data Acquisition: Use modal testing or component modal calculation to obtain the center frequency of the constraint mode above 1KHz of the installed component at 3 measurement points, and calculate the carrier frequency range; collect the parameters of 3 measurement points during diesel engine operation, and use a 5Hz high-pass filter to filter out low noise in vibration testing.

[0120] Step 2, Spatial Response Data Processing: The data collected in Step 1 at measurement points 1, 2, and 3 are processed according to the synchronous time-domain calculation method (1-2), (1-2+3), and (2-3) to obtain the corresponding (RY, Z) degrees of freedom, (RZ, Y) degrees of freedom, and (RX, X) degrees of freedom.

[0121] Step 3, Data Preprocessing: For the time-domain results (1-2), (1-2+3), and (2-3) calculated in Step 2, bandpass filtering is set according to the carrier frequency range obtained in Step 1. Bandpass filtering, envelope extraction, and FFT (Fast Fourier Transform) are performed on each response result, as well as direct FFT and integration on each response result, resulting in six amplitude and phase spectra. For detecting the diesel engine operating speed without a speed sensor, the results from measurement point 1 acquired in Step 1 are used for FFT to form one amplitude and phase spectrum for virtual speed extraction.

[0122] Step 4: Calculation of crankshaft friction pair wear index: Using the amplitude spectrum and phase spectrum extracted in Step 3, scan the amplitude from 5Hz to 75Hz to obtain an index greater than 0.02m·s. 2The virtual switching frequency is determined based on the condition that the phase |maximum-minimum| within the frequency range of fr±0.5 is ≥100°, thus forming the working speed parameters. The carrier amplitude spectra of (1-2), (1-2+3), and (2-3) are obtained by using bandpass filtering → envelope → FFT, and a tuning function is constructed according to the virtual switching frequency. The tuning function is multiplied with the carrier FFT result, and then integral operation is performed. At the same time, the responses of (1-2), (1-2+3), and (2-3) are directly FFT → integral calculation to synchronously map the crankshaft trajectory, spatial wear rate, and load rate. Then, weighted synthesis is performed to form the wear degree, wear rate, and load rate indicators.

[0123] Step 5: The equipment outputs real-time indicators of crankshaft friction pair load rate (%), wear degree (%), and uneven wear degree (%) at the indicated operating speed.

[0124] The specific implementation method is as follows:

[0125] B1: Determination of carrier frequency band for measuring point installation components: Select the self-excited frequency band of the diesel engine components at the installation positions of sensors 1, 2, and 3 based on ease of operation.

[0126] When using computation to solve for the self-excited frequency band, the component model of the installation location is independently imported into the modal analysis software. Constraints are set according to the actual fixed position of the component, and constrained modal solutions are performed. The modal calculation frequency is not lower than 4kHz, and the first center frequency f with relatively large damping above 1kHz is obtained. i0 (i=1, 2, 3, representing the center frequency of the i-th measurement point), and according to Solve for the upper and lower limits of the frequency band range f i1 f i2 .

[0127] When using the detection method, a model detection sensor is placed at the measurement point, and the channel sampling frequency is set to be no less than 6kHz. A high-frequency steel hammer is used to strike the fixing bolts of the corresponding measurement point mounting component to obtain the center frequency with relatively large damping above 1kHz, and the frequency f is then obtained. i0 ,according to Solve for the upper and lower limits of the frequency band range f i1 f i2 .

[0128] B2: Construction of monitoring spatial phase response: Based on the simplest measurement point layout and the determined measurement point numbering order (sensor 1, 2, 3), the spatial phase relationship is reconstructed. (1-2) characterizes the overturning and vertical translation (RY, Z) degree of freedom response introduced by the crankshaft's revolution; (1-2+3) characterizes the left and right yaw and forward and backward sway (RZ, Y) degree of freedom response introduced by the crankshaft's revolution; (2-3) characterizes the vertical pitch and left and right lateral movement (RX, X) degree of freedom response introduced by the crankshaft's revolution.

[0129] B3: The spatial phase response obtained by B2 is calculated according to the initial wear monitoring and process wear monitoring calculation paths. The initial wear monitoring uses the carrier frequency range measured by B1 to set the bandpass filter frequency. The results of (1-2), (1-2+3), and (2-3) are processed by bandpass filtering → envelope extraction → FFT to form the amplitude spectra of X2(f), X4(f), and X6(f) with three degrees of freedom. The process wear monitoring calculation path directly performs FFT calculation on the results of (1-2), (1-2+3), and (2-3), and after integration, forms the amplitude and phase spectra of X1(f), X3(f), and X5(f) with three degrees of freedom. In order to obtain the virtual rotation speed, the data of measurement point 1 obtained by B1 is directly used to perform FFT calculation to form the amplitude and phase spectrum of X0(f).

[0130] B4: Virtual Rotation Speed ​​Channel Processing: Utilizing the X0(f) amplitude and phase spectrum calculated in B3, the process proceeds as follows: amplitude spectrum peak retrieval → determination of the first center frequency fr → phase spectrum statistics within the frequency range extended by fr → phase spectrum data inversion determination → virtual rotation frequency determination → calculation of virtual rotation speed. Specific parameters in each step are: the number of spectral lines for FFT calculation is set with a frequency resolution of 0.5 Hz; amplitude spectrum peak retrieval is performed in increments from low to high within the 5~75 Hz range to find values ​​greater than 0.02 m·s. 2 The first center frequency *fr* is used to identify whether the phase data within the range of *fr* ± 0.5 in the phase spectrum meets the condition "|maximum - minimum| ≥ 100°". If the phase determination condition is met, the virtual engine operating speed is solved using *fr* × 60; otherwise, the amplitude spectrum is scanned further to find values ​​greater than 0.02 m / s. 2 The scanning continues until the phase data within the range of fr ± 0.5 in the phase spectrum is identified and the |maximum - minimum| ≥ 100° is satisfied. If the detected first center frequency is 5Hz, the system is considered to be in a stopped state.

[0131] B5: Diesel engine load index processing: Using the X6(f) amplitude spectrum calculated in B3, according to the amplitude spectrum (|X6(f)|) × tuning function Then, perform integration calculations and compare the amplitude spectrum after integration with X5(f). Simultaneously, map the load rate Tcr6 from the initial wear monitoring and the load rate Tcr5 from the process wear monitoring, using a smoothness weighting function. Multiply by the initial wear monitoring mapping load rate Tcr6, and then add it to the process wear monitoring load rate Tcr5 to synthesize the normalized load index Tcr.

[0132] Tuning function The expression is as follows:

[0133] ;

[0134] In the formula, Let f denote the tuning function, f denote the frequency, i denote the sequence of tuning functions, and fv denote the virtual frequency transition;

[0135] The load rate mapping method is as follows:

[0136] The expression for the load rate mapped to the initial wear stage is as follows:

[0137] ;

[0138] In the formula, Indicates the load rate in the initial stage of wear. fv represents the amplitude at the selected frequency in the X6 amplitude spectrum;

[0139] The expression for process wear mapping load rate is as follows:

[0140] ;

[0141] In the formula, This indicates the process wear mapping load rate. fv represents the amplitude at the selected frequency in the X5 amplitude spectrum;

[0142] Smoothness weighting function The expression is as follows:

[0143] ;

[0144] In the formula, This represents the smoothness weighting coefficient. This represents the cumulative sum within the range of 5 to 200 Hz. This represents the amplitude at a selected frequency in the X5 amplitude spectrum, where f represents the frequency;

[0145] The expression for the load factor metric is as follows:

[0146] ;

[0147] In the formula, Indicates load rate, This represents the smoothness weighting coefficient. This indicates the process wear mapping load rate. This indicates the load rate in the initial stage of wear.

[0148] B6: Processing of wear index of diesel engine crankshaft friction pair: Using the X2(f) amplitude spectrum calculated in B3, according to the amplitude spectrum (|X2(f)|) × tuning function Then, an integral calculation is performed, and the amplitude spectrum after integration with X1(f) is obtained. At the same time, the wear index Mcr2 of the initial wear stage and the wear index Mcr1 of the process wear monitoring are mapped, using a wear weighting function. Multiply by the wear index Mcr1 mapped from the wear process monitoring, and then add it to the wear index Mcr2 monitored in the initial stage of wear to synthesize the normalized wear index Mcr.

[0149] Tuning function The expression is as follows:

[0150] ;

[0151] In the formula, Let f denote the tuning function, f denote the frequency, i denote the sequence of tuning functions, and fv denote the virtual frequency transition;

[0152] The wear index mapping method is as follows:

[0153] The expression for mapping wear degree to the initial wear stage is as follows:

[0154] ;

[0155] In the formula, This indicates the initial stage of wear mapping the degree of wear. fv represents the amplitude at a selected frequency in the X2 amplitude spectrum;

[0156] The expression for mapping process wear to wear degree is as follows:

[0157] ;

[0158] In the formula, This indicates the wear rate as a mapping of process wear. fv represents the amplitude at the selected frequency in the X1 amplitude spectrum;

[0159] Mapping wear weighting function The expression is as follows:

[0160] ;

[0161] In the formula, This indicates a weighted mapping of wear levels. This indicates the load rate, and fv indicates the virtual switching frequency;

[0162] The expression for the wear index is as follows:

[0163] ;

[0164] In the formula, Indicates wear level, This indicates the wear rate as a mapping of process wear. This indicates the initial stage of wear mapping the degree of wear. This indicates a weighted mapping of wear levels.

[0165] B7: Processing of diesel engine crankshaft friction pair wear index: Using the X4(f) amplitude spectrum calculated by S3, according to the amplitude spectrum (|X4(f)|) × tuning function Then, an integral calculation is performed, and the amplitude spectrum after integration with X3(f) is compared. Simultaneously, the wear index Mcr4 of the initial wear stage and the wear index Mcr3 of the process wear monitoring are mapped, using a wear weighting function. Multiply by the wear index Mcr4, which is the initial wear monitoring mapping index, and then add it to the wear index Mcr3, which is the wear monitoring during the wear process, to synthesize the normalized wear index Mcpr.

[0166] Tuning function The expression is as follows:

[0167] ;

[0168] In the formula, Let f denote the tuning function, f denote the frequency, i denote the sequence of tuning functions, and fv denote the virtual frequency transition;

[0169] The method for mapping the wear index is as follows:

[0170] The expression is as follows:

[0171] ;

[0172] In the formula, This indicates the degree of wear mapped in the initial stage of wear. fv represents the amplitude at a selected frequency in the X4 amplitude spectrum;

[0173] The expression for process wear mapping to wear degree is as follows:

[0174] ;

[0175] In the formula, This indicates the wear pattern mapped to the wear degree during the process. fv represents the amplitude at the selected frequency in the X3 amplitude spectrum;

[0176] Mapping wear weighting function The expression is as follows:

[0177] ;

[0178] In the formula, This represents the weighting coefficient for the mapped wear degree. This indicates the load rate, and fv indicates the virtual switching frequency;

[0179] The expression for the wear index is as follows:

[0180] ;

[0181] In the formula, Indicates the degree of wear. This indicates the wear pattern mapped to the wear degree during the process. This indicates the degree of wear mapped in the initial stage of wear. This represents the weighting coefficient for the mapped wear degree.

[0182] Example 1: As Figures 3 to 9 As shown, the simplest vibration measurement point arrangement for crankshaft wear monitoring

[0183] C1: Model Preparation: This mainly includes preparing the diesel engine model and the mounting base model, importing them into the CAD software, confirming the completeness and correctness of material properties, and adjusting the origin of the diesel engine model's coordinate system to the centroid. Figure 3 and Figure 4 As shown.

[0184] C2: Diesel engine parameter calculation: Using CAD tools, the calculation includes the diesel engine moment of inertia, base mounting position coordinates, base static stiffness, and base mounting angle; as shown in Table 1, moment of inertia calculation; as shown in Table 2, static stiffness calculation; as shown in Table 3, base mounting angle calculation; and as shown in Table 4, base mounting position calculation.

[0185] Table 1

[0186]

[0187] Table 2

[0188]

[0189] Table 3

[0190]

[0191] Table 4

[0192]

[0193] C3: Assembly Calculation Matrix: Includes the assembly of the inertia matrix M, base distance matrix B, base stiffness matrix KK, and base mounting angle matrix T, as shown below:

[0194] ;

[0195] ;

[0196] ;

[0197] .

[0198] C4: Synthesizing the Full-Rank Stiffness Matrix: Using the base distance matrix B, base stiffness matrix KK, and base mounting angle matrix T, a 6x6 matrix is ​​synthesized to resolve singularities. The synthesized full-rank stiffness matrix is ​​shown below:

[0199] .

[0200] C5: Establish the crankshaft orientation matrix and the rotation matrix, and construct the crankshaft orientation matrix based on the working axis and rotation direction of the diesel engine crankshaft. and rotating array ;

[0201] C6: Solve for the transformation matrices of the elastic axis and the torque axis: Solve for the torque axis transformation matrix based on the assembly inertia matrix M and the rotation axis matrix Traf, and solve for the elastic axis transformation matrix based on the full-rank stiffness synthesis matrix and the elastic axis transformation matrix f.

[0202] C7: Constructing the elastic axis and torque axis: This involves substituting the elastic axis transformation matrix and the torque axis transformation matrix to solve for the four coordinate points TLS, TLE, ELS, and ELE, and connecting the corresponding coordinate points pairwise to form the elastic axis and torque axis. Figure 5 As shown.

[0203] C8: Construct the projection of the torque axis onto the outer contour of the diesel engine, and extend the elastic axis to the intersection with the transmission box: This includes drawing a vertical plane perpendicular to the diesel engine through the elastic axis, drawing the line of symmetry of the torque axis through the vertical plane, projecting the torque axis onto the outer contour of the diesel engine; and extending the axis of the elastic axis; such as Figure 6 and Figure 7 As shown.

[0204] C9: Determine the installation diagram with the simplest three measuring point positions, such as... Figure 8 and Figure 9 As shown.

[0205] Example 2: A method for identifying crankshaft wear characteristics based on the simplest vibration measurement point arrangement.

[0206] D1: Virtual speed channel determination, such as Figure 10 As shown.

[0207] D2: Conduct a full-speed, full-load stress test on a certain type of diesel engine, monitoring the speed and load rate, such as... Figures 11 to 12 As shown; when the pedal is fixed at the full stroke position and the output is stable at full speed and full load, the load monitoring fluctuation of a certain type of diesel engine is confirmed to be a maximum of 2%. At a partial pedal position, the load rate monitoring fluctuation is a maximum of 5%, which meets the general condition assessment monitoring requirements.

[0208] D3: Conduct crankshaft friction pair tests on a certain type of diesel engine under full-speed partial load with adjusted combustion parameters, monitoring speed, load rate, and wear degree, such as... Figure 13 As shown; under stable full-speed partial load output, after confirming the stable operation of a certain type of diesel engine, the combustion parameters of the engine with abnormal wear characteristics are adjusted to increase the load of the crankshaft friction pair. The wear index is positively correlated with the load change and the adjustment parameters. When the combustion parameters are abnormal, the wear process changes drastically, which meets the requirements for crankshaft friction pair condition monitoring.

[0209] The technical problem solved by this invention:

[0210] (1) Based on the characteristics of vibration signal sensitivity to force and the non-invasive nature of installation process, this invention addresses the complexity of diesel engine vibration monitoring signals and their correlation with crankshaft friction pair wear. Considering the lack of information in single-channel vibration monitoring signals, making it difficult to reliably predict abnormal working conditions, and the problems of large waveform differences at multiple measurement points, difficulty in unifying processing characteristics, large computational load, difficulty in online deployment, and scenario adaptability of multi-channel vibration monitoring signals, this invention proposes a simplest vibration measurement point arrangement method and a crankshaft shaft system wear characteristic identification method based on the simplest vibration measurement point arrangement method.

[0211] (2) The present invention proposes a simplified vibration measurement point arrangement method, which focuses on solving the problem of optimal simplified layout for sensitive monitoring of crankshaft friction pair wear. This facilitates the spatial phase consistency between the monitoring characteristics and the installation position, and is a method for filtering physical environmental interference. The simplified layout is mainly based on the angle between the elastic working axis introduced by the diesel engine support point and the torque axis introduced by the engine body center of mass. By establishing a symmetry plane based on the elastic axis and the crankshaft working axis, and the intersection of the symmetry plane and the two lines, the test installation point on the upper edge of the diesel engine is projected to form a vibration sensor installation pair that represents the revolution characteristics of the diesel engine center, to monitor the radial wear of the crankshaft friction pair. In addition, an axial vibration monitoring sensor is added at the crankshaft position on the gearbox side, constituting the spatial degree of freedom element for complete crankshaft wear monitoring. Based on this, only a three-vibration monitoring measurement point arrangement scheme is needed to test the revolution rotation of the entire diesel engine to map the wear of the crankshaft friction pair.

[0212] (3) The crankshaft wear characteristic identification method based on the simplest vibration measuring point arrangement method proposed in this invention focuses on solving the problem of identifying the correlation between the relative characteristic parameters and the wear degree of the crankshaft friction pair based on the simplest sensor installation pair. It mainly uses the spatial phase of the three simplest sensors proposed in the previous step as the basis, and utilizes the evolution process of the excitation force carrier from the initial abnormal wear symptoms of the crankshaft friction pair to the off-center load frequency response of the severely worn shaft system. Through modal calculation method or speed-up scanning detection method, the carrier frequency band of the measuring point position is obtained to check the abnormal wear symptoms process. When the symptoms monitoring exceeds the limit, the rotor radial working mode is reconstructed by using the frequency combination in the diesel engine frequency to enhance the identification of wear degree.

[0213] (4) This invention provides a vibration-based method for identifying the wear characteristics of a diesel engine crankshaft, including a simplified vibration measurement point arrangement method for crankshaft wear monitoring and a crankshaft system wear characteristic identification method based on the simplified vibration measurement point arrangement method. From the fixed spatial phase arrangement of sensors to the extraction of relative phase characteristics and difference spectrum characteristics between sensors, and then to the monitoring and processing of associated wear and the display of wear during synchronous operation, this invention provides an online accompanying wear level monitoring method for diesel engines, ensuring reliable monitoring of crankshaft wear anomalies during research and development calibration and subsequent use.

[0214] Advantages and benefits of this invention:

[0215] (1) This invention solves the problem of real-time tracking, monitoring and evaluation of wear of crankshaft friction pairs in newly developed enhanced diesel engines. When matching new components such as fuel supply and combustion, as well as high explosion pressure and high indication characteristics, the safety margin of crankshaft friction pairs can be quickly determined to determine whether subsequent adjustment schemes can be safely implemented. At the same time, this invention can also be used for testing the working performance of in-use diesel engines, providing a safety guarantee for the working reliability of high-value diesel engines.

[0216] (2) In order to make the monitoring equipment easy to install and the diesel engine results not to be changed during installation, the present invention provides the simplest sensor arrangement method, which proposes to use the elastic working shaft and torque working shaft with the inherent characteristics of the diesel engine as the arrangement basis, and to monitor shaft system problems by arranging vibrations in symmetrical positions of the diesel engine. The introduced reverse torque response change is utilized. At the same time, in the algorithm, considering the problem of inconsistent monitoring indicators introduced by different installation methods and different road conditions, the spatial degree of freedom response difference is constructed under synchronous sensor detection to remove the in-phase results introduced by external excitation, combustion excitation and interference.

[0217] (3) In order to make the monitoring method related to the working conditions of the diesel engine and to specifically evaluate the wear characteristics of low speed light load, high speed light load and high speed high load, without installing speed and torque sensors, this invention proposes a virtual frequency determination method based on amplitude sweep frequency and phase difference determination, so that the response rate of the virtual frequency can be synchronously indicated with the wear index, which facilitates the backtracking of the working speed during the monitoring process. This invention also provides a load rate determination index, which takes the characteristics introduced by the working response and load demand of the diesel engine as the benchmark, constructs the relationship between the reaction torque and the working response, and normalizes and removes the viscous damping coefficient to form a load rate index that represents the power output of the diesel engine.

[0218] (4) In order to enhance the real-time monitoring of the wear of the crankshaft friction pair of the diesel engine, the wear degree is mapped by the constructed (RY, Z) spatial degree of freedom response. Based on the principle of equivalent rigidity of crankshaft working, the wear of the friction pair shows the decrease of the constraint of the engine body on the crankshaft revolution degree of freedom, the strengthening of the off-center load of the diesel engine components by the frequency excitation, and the significant component carrier. The relative carrier and off-center load difference frequency increment are extracted to form a normalized mapping index. The weight coefficient is constructed with the characteristics of low speed light load, high speed light load, low speed high load, and high speed high load to realize the crankshaft wear degree monitoring effect related to the working load of the diesel engine.

[0219] (5) In order to further indicate the wear characteristics of the crankshaft friction pair of lightweight and weak stiffness diesel engine, the wear index is mapped by the bending degree correlation of the crankshaft in the flexible state using the constructed (RZ, Y) spatial degree of freedom response. Based on the elliptical trajectory characteristics of the diesel engine operation process, the crankshaft is driven to bend. A normalized index is proposed to correlate the trajectory and response. The effective output of the diesel engine crankshaft and the reaction response characteristics of the load are used as the two monitoring sources to determine the relationship between the trajectory shape and the wear response amplitude. The roundness degradation is used as the maximum tolerance limit of the absolute monitoring response to achieve the monitoring effect of the wear degree of the crankshaft friction pair.

[0220] (6) The computational complexity of the monitoring and evaluation indicators provided by this invention is suitable for current mainstream edge acquisition equipment, and it is easy to achieve miniaturization to meet the requirements of power-accompanying monitoring. Moreover, the monitoring investment cost is low, which facilitates the full life cycle monitoring of high-value diesel engines. At the same time, the arrangement provided by this invention combines the characteristics of the physical structure and working parts of the diesel engine itself. The identification method uses normalized indicators, and the monitoring limit does not depend on the determination of long-term statistical results. It is suitable for monitoring the first working characteristics of newly developed enhanced diesel engine products, as well as meeting the monitoring requirements of different diesel engines under different working conditions. The indicator evaluation has good portability and can provide effective assessment guarantee for wear status for scientific research and users.

[0221] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A vibration-based method for identifying the wear characteristics of a diesel engine crankshaft, characterized in that: Includes the following steps: S1. Simplified vibration measurement point layout for crankshaft wear monitoring; S2. Based on the simplest vibration measurement point layout, feature identification of crankshaft system wear is performed. In step S1, the simplified vibration measurement point arrangement for crankshaft wear monitoring includes: S11. Prepare the diesel engine model and the mounting base model, import them into CAD, confirm the material properties, and adjust the origin of the diesel engine model coordinate system to the centroid. S12. Diesel engine parameter calculation: Use CAD tools to calculate the diesel engine moment of inertia, base mounting position coordinates, base static stiffness, and base mounting angle; S13. Based on the diesel engine parameters, assemble the calculation matrix, which includes the inertial matrix, the base distance matrix, the base stiffness matrix, and the base mounting angle matrix. S14. Based on the base distance matrix, base stiffness matrix and base installation angle matrix, synthesize a full-rank stiffness matrix; S15. Establish the crankshaft direction array and the shaft array; S16. Solve for the torque axis transformation matrix based on the inertial matrix and the rotation axis matrix; solve for the elastic axis transformation matrix based on the full-rank stiffness matrix and the crankshaft direction matrix. S17. Construct the torque axis and elastic axis based on the torque axis transformation matrix and the elastic axis transformation matrix; S18. Construct the torque shaft projection onto the outer contour of the diesel engine, and extend the elastic shaft to the intersection with the transmission box; S19. Determine the locations of the three measuring points.

2. The method for identifying the wear characteristics of a diesel engine crankshaft based on vibration according to claim 1, characterized in that: In step S18, the torque shaft is projected onto the outer contour of the diesel engine, and the elastic shaft is extended to the intersection with the transmission box, including: Draw a vertical plane perpendicular to the diesel engine through the elastic axis, draw the line of symmetry of the torque axis through the vertical plane, and project the torque axis to the outer contour of the diesel engine; extend the axis of the elastic axis.

3. The method for identifying the wear characteristics of a diesel engine crankshaft based on vibration according to claim 1, characterized in that: In step S19, the locations of three measuring points are determined, including: S191. Based on the two intersection points of the torque axis projection line and the outer contour of the diesel engine, determine the first and second measuring points; based on the intersection point of the elastic axis and the end face of the transmission box, determine the third measuring point. S192. Based on the sensor operating temperature and the surface mounting characteristics of the diesel engine, determine whether the actual layout is met. If not, adjust the position based on the torque axis projection line. S193. Determine the locations of the three measuring points.

4. The method for identifying the wear characteristics of a diesel engine crankshaft based on vibration according to claim 1, characterized in that: In step S2, based on the simplest vibration measurement point arrangement, the wear degree of the crankshaft system is characterized, including: S21. Parameter preparation: Calculate the carrier frequency range; Data acquisition: Obtain data from three measurement points. S22. Based on the data from three measurement points, perform spatial response data processing to obtain the response results for three degrees of freedom; S23. Based on the carrier frequency range and degree of freedom response results, perform data preprocessing to obtain the amplitude spectrum and phase spectrum; S24. Calculate the wear index of crankshaft friction pair based on amplitude spectrum and phase spectrum; S25, Real-time output of crankshaft friction pair wear indicators.

5. The method for identifying the wear characteristics of a diesel engine crankshaft based on vibration according to claim 4, characterized in that: In step S21, parameters are prepared and the carrier frequency range is calculated; Data acquisition was conducted, obtaining data from three measurement points, including: S211. Parameter preparation: Using the modal testing method or component modal calculation method, obtain the constraint mode center frequency above 1KHz of the component installed at three measurement points, and calculate the carrier frequency range. S212. Data Acquisition: Collect parameters from three measurement points respectively, and filter them using a 5Hz high-pass filter to obtain data from measurement point one, measurement point two, and measurement point three.

6. The method for identifying the wear characteristics of a diesel engine crankshaft based on vibration according to claim 5, characterized in that: In step S22, spatial response data processing includes: S221. The time-domain results of measuring point one minus measuring point two characterize the overturning and vertical translation (RY, Z) degrees of freedom response results introduced by the crankshaft's revolution. S222, the time-domain results of measuring point one minus measuring point two plus measuring point three characterize the response results of the left and right yaw and forward and backward sway (RZ, Y) degrees of freedom introduced by the crankshaft's revolution; S223, the time-domain results of measuring point two minus measuring point three characterize the response results of the vertical pitch and horizontal lateral (RX, X) degrees of freedom introduced by the crankshaft's revolution.

7. The method for identifying the wear characteristics of a diesel engine crankshaft based on vibration according to claim 6, characterized in that: In step S23, data preprocessing is performed to obtain the amplitude spectrum and phase spectrum, including: S231. For the time domain results of measurement point 1 minus measurement point 2, measurement point 1 minus measurement point 2 plus measurement point 3, and measurement point 2 minus measurement point 3 in step S22, set the bandpass filter according to the carrier frequency range of step S211. S232. Perform bandpass filtering, envelope extraction and fast Fourier transform on the response results of steps S221, S222 and S223 respectively to form amplitude spectrum two, amplitude spectrum four and amplitude spectrum six. S233. Perform Fast Fourier Transform and Integration on the response results of steps S221, S222 and S223 respectively to form amplitude spectrum one and phase spectrum one, amplitude spectrum three and phase spectrum three, and amplitude spectrum five and phase spectrum five. S234. Perform a fast Fourier transform on the data from measurement point 1 to generate the amplitude spectrum zero and the phase spectrum zero.

8. The method for identifying the wear characteristics of a diesel engine crankshaft based on vibration according to claim 7, characterized in that: In step S24, the wear index of the crankshaft friction pair is calculated, including: S241. Based on the zero amplitude spectrum and zero phase spectrum obtained in step S234, perform an amplitude scan within the range of 5Hz-75Hz to obtain values ​​greater than 0.02m·s. 2 The first center frequency fr; S242. Based on the phase within the frequency range of the first center frequency fr ± 0.5, and with the condition that |maximum phase - minimum phase| ≥ 100°, determine the virtual rotational frequency to form the working speed parameters; S243. Construct a tuning function based on virtual frequency conversion; S244. For amplitude spectrum two, amplitude spectrum four, and amplitude spectrum six, multiply them with the tuning function and then perform integration. S245. For amplitude spectrum two, amplitude spectrum four and amplitude spectrum six, as well as amplitude spectrum one, amplitude spectrum three and amplitude spectrum five, the crankshaft trajectory, spatial wear rate and load rate are synchronously mapped, and then weighted and synthesized to form wear degree, wear rate and load rate indicators.

9. The method for identifying the wear characteristics of a diesel engine crankshaft based on vibration according to claim 4, characterized in that: In step S25, the crankshaft friction pair wear index is output in real time, including: The system provides real-time output of crankshaft friction pair load rate, wear degree, and uneven wear degree indicators at the operating speed.

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