An internal combustion engine fault test system based on vibration signal extraction

Abstract

The present application relates to the internal combustion engine state monitoring and fault diagnosis technical field, specifically to a kind of internal combustion engine fault test system based on vibration signal extraction, including multi-source signal acquisition module, signal processing module, vibration energy calculation module, fault judging module and control protection module;Synchronous acquisition vibration acceleration signal, crankshaft pulse signal and ambient temperature signal, generate link state word;According to link state word, temperature compensation and data interpolation repair are carried out, according to crankshaft pulse signal, instantaneous speed is calculated and hardware sampling clock is adjusted, angular domain vibration acceleration signal is generated, then filtering is carried out according to dynamic filter coefficient;Instantaneous speed and signal amplitude are combined to calculate target working condition characteristic energy value, and according to background energy threshold and alarm threshold, conventional monitoring, encryption monitoring or alarm processing result is output, to reduce misjudgment;The present application effectively solves the problem that fault feature is easily submerged by strong background noise under variable working condition, and improves the accuracy of feature extraction.

Description

Technical Field

[0001] This invention relates to the field of internal combustion engine condition monitoring and fault diagnosis technology, specifically to an internal combustion engine fault testing system based on vibration signal extraction. Background Technology

[0002] As an important technical means to ensure the safety of engine testing and the verifiability of its operating status, the internal combustion engine fault testing system usually needs to collect and analyze vibration signals during operation in scenarios such as bench testing, durability testing and variable operating condition performance testing. Therefore, the accuracy of fault feature extraction directly affects the reliability of test results and the timeliness of protection actions. Existing testing methods have many problems. For example, they often use fixed-time sampling, fixed filtering parameters, and fixed alarm thresholds. When there are fluctuations in speed, high temperature environments, and strong background noise, the sampling reference is easily unstable, the signal amplitude is distorted, and the fault characteristics are easily affected by background vibration and are difficult to extract. Especially when there is short-term data loss in the data link, channel time is not synchronized, or the operating conditions are switched rapidly, it is difficult to accurately identify abnormal states and cannot effectively balance false alarm suppression and sudden fault response. Summary of the Invention

[0003] The purpose of this invention is to provide an internal combustion engine fault testing system based on vibration signal extraction, and to solve the following technical problems: It avoids the problems of unstable fault characteristics, weak fault characteristics being easily submerged by noise, and increased false triggering caused by the lack of link health judgment, temperature correction mechanism, angular domain reference and adaptive filtering mechanism in existing technologies. It can also effectively reduce the misjudgment caused by strong background noise, speed fluctuation and link abnormality, and achieve more stable and accurate classification judgment of the internal combustion engine operating status under complex working conditions and reliable shutdown or alarm protection.

[0004] The objective of this invention can be achieved through the following technical solutions: An internal combustion engine fault testing system based on vibration signal extraction includes: a multi-source signal acquisition module, which synchronously acquires vibration acceleration signals, crankshaft pulse signals and ambient temperature signals during the operation of the internal combustion engine, monitors the integrity of multiple access data channels, and generates link status words; The signal processing module performs temperature compensation and data interpolation repair based on the link status word, calculates the instantaneous speed based on the crankshaft pulse signal and adjusts the hardware sampling clock, generates angular domain vibration acceleration signals with equal angular intervals, and extracts the dynamic filtering coefficients corresponding to the current speed to filter the angular domain vibration acceleration signals. The vibration energy calculation module calculates the characteristic energy value of the target working condition by combining the instantaneous rotational speed, dynamic filtering coefficient, and signal amplitude of the filtered angular domain vibration acceleration signal. The fault diagnosis module has built-in background energy threshold and alarm threshold. When the target operating condition characteristic energy value is less than the background energy threshold, it performs regular monitoring; when the target operating condition characteristic energy value is greater than or equal to the background energy threshold and less than or equal to the alarm threshold, it performs encrypted monitoring; when the target operating condition characteristic energy value is greater than the alarm threshold, it triggers alarm processing and generates a shutdown command or an audible and visual alarm command. The control and protection module is connected to the multi-source signal acquisition module and the fault judgment module respectively, executes the shutdown command or the audible and visual alarm command, and monitors the safety status during the test process.

[0005] Furthermore, the signal processing module includes a link compensation unit, an angular domain synchronization unit, and a filtering and noise reduction unit; The link compensation unit is used to parse the link status word, extract the lost signal segments, and output the vibration acceleration signal after temperature compensation and repair. The angular domain synchronization unit is used to analyze the instantaneous rotational speed, obtain the time interval corresponding to the preset target angular domain resolution, and output the clock frequency control word to the hardware sampling clock to generate the angular domain vibration acceleration signal. The filtering and noise reduction unit is used to analyze the angular domain vibration acceleration signal, distinguish the background noise frequency band and the fault characteristic frequency band, extract the filter coefficients corresponding to the current rotational speed as dynamic filter coefficients, and output the filtered angular domain vibration acceleration signal to the vibration energy calculation module.

[0006] Furthermore, the vibration energy calculation module is configured to perform energy smoothing on the filtered angular domain vibration acceleration signal within a preset number of crankshaft rotation cycles, and to weight it in combination with the historical state energy average read from the memory to generate a target working condition characteristic energy value for characterizing the degree of transient mechanical vibration energy anomaly.

[0007] Furthermore, the fault diagnosis module includes a pre-stored benchmark threshold table, which records the average background energy, standard deviation of background energy, and alarm coefficient used to control alarm sensitivity under different speed conditions. The background energy threshold corresponds to the mean background energy. The alarm threshold is the sum of the products of the mean background energy, the standard deviation of the background energy, and the alarm coefficient. When the rate of change of the target operating condition characteristic energy value is greater than or equal to the preset mutation rate, and the duration is greater than or equal to the preset judgment period, the fault judgment module will forcibly switch the current state to the alarm processing state.

[0008] Furthermore, after the alarm is triggered, the following operations are performed: Record the speed and temperature parameters of the internal combustion engine under the current test conditions; Switch the acquisition mode of the multi-source signal acquisition module to increase the sampling frequency of the vibration acceleration signal of the abnormal channel indicated by the link status word; Record the status data at the time of the alarm, and extract the compensation status at the time of the alarm and the version number of the filter parameter corresponding to the current dynamic filter coefficient; Save the abnormal state type determined based on the target operating condition characteristic energy value, as well as the abnormal channel number indicated by the link status word, as the basis for generating subsequent diagnostic reports.

[0009] Furthermore, the control and protection module incorporates a multi-level protection mechanism; The first level of protection is synchronous verification protection. When the time alignment error between the data channels of the multi-source signal acquisition module is greater than or equal to the preset alignment threshold, the current alarm judgment logic is frozen and only the retest data is uploaded. The second level of protection is the filter switching buffer protection. When the operating condition switch causes the filter coefficient to be updated, the fault judgment output is blocked within the transition buffer window. The third level of protection is continuous over-limit shutdown protection. When the energy value of the target operating condition is detected to be continuously greater than or equal to the alarm threshold and reaches or exceeds the preset number of rotation cycles, a high-level signal is forcibly output through the hardware interface to trigger an external programmable logic controller or relay to perform shutdown.

[0010] Furthermore, the system also includes a host computer management module; The host computer management module is used to automatically record data throughout the entire process from the start to the end of the test. The data includes basic characteristic parameters, characteristic energy data, link anomaly statistics logs, and judgment instruction logs. The host computer management module has built-in report templates that can automatically generate standardized reports containing test conditions, process summaries, key parameter curves, and status conclusions based on the recorded data.

[0011] Furthermore, the link compensation unit is configured to determine the temperature difference between the current ambient temperature corresponding to the ambient temperature signal and the reference calibration temperature, and to determine a temperature compensation coefficient reflecting the degree of thermal drift based on the temperature difference, so as to correct the amplitude attenuation of the vibration acceleration signal caused by high temperature.

[0012] Furthermore, the angular domain synchronization unit is configured to determine and output a target clock frequency for controlling the hardware sampling clock based on the set target angular domain resolution and instantaneous rotational speed.

[0013] Furthermore, the host computer management module is also used to analyze historical test data, distinguish historical test data at specific speeds, distinguish the combustion background noise frequency band and the mechanical background noise frequency band at specific speeds, use noise separation methods to separate background noise from fault signals, calculate filter coefficients based on the maximum signal-to-noise ratio of the target fault frequency band, and then send the filter coefficients to the signal processing module as the basis for extracting dynamic filter coefficients for real-time updates.

[0014] The beneficial effects of this invention are: 1. This invention monitors channel integrity through a multi-source signal acquisition module to generate a link status word, and combines ambient temperature signals to perform temperature compensation and data interpolation repair on vibration signals. Simultaneously, it uses crankshaft pulse signals to calculate instantaneous rotational speed to directly adjust the hardware sampling clock, generating angular domain vibration acceleration signals with equal angular intervals, and extracting dynamic filtering coefficients corresponding to the current rotational speed for filtering. This design transforms signals that are originally susceptible to high-temperature amplitude attenuation and short-term packet loss into effective analysis data, and transforms time-domain unstable phase distortion into stable angular domain sampling, effectively solving the problem that fault features are easily submerged by strong background noise under varying operating conditions, and improving the accuracy of feature extraction. 2. This invention uses a vibration energy calculation module to perform single-point squaring, single-cycle accumulation, time-window moving average, and weighted summation of historical state energy averages on the filtered signal to generate target operating condition characteristic energy values. The fault judgment module then performs graded judgments based on the pre-stored background energy average and alarm standard deviation under different speed conditions, and executes forced alarm switching in conjunction with mutation rate monitoring. This scheme changes the limitations of traditional fixed-time sampling and fixed-threshold judgment, which can both reduce false triggering caused by occasional spike noise by using a multi-layer energy aggregation mechanism and quickly judge rapidly unstable and deteriorating operating conditions. Attached Figure Description

[0015] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of a module of an internal combustion engine fault testing system based on vibration signal extraction provided in an embodiment of this application. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Please see Figure 1An internal combustion engine fault testing system based on vibration signal extraction includes: a multi-source signal acquisition module, which synchronously acquires vibration acceleration signals, crankshaft pulse signals and ambient temperature signals during the operation of the internal combustion engine, monitors the integrity of multiple data channels connected to the system, and generates link status words; The signal processing module performs temperature compensation and data interpolation repair based on the link status word, calculates the instantaneous speed based on the crankshaft pulse signal and adjusts the hardware sampling clock, generates angular domain vibration acceleration signals with equal angular intervals, and extracts the dynamic filtering coefficients corresponding to the current speed to filter the angular domain vibration acceleration signals; The vibration energy calculation module calculates the characteristic energy value of the target working condition by combining the instantaneous rotational speed, dynamic filtering coefficient, and signal amplitude of the filtered angular domain vibration acceleration signal. The fault diagnosis module has built-in background energy threshold and alarm threshold. When the target operating condition characteristic energy value is less than the background energy threshold, it performs regular monitoring; when the target operating condition characteristic energy value is greater than or equal to the background energy threshold and less than or equal to the alarm threshold, it performs encrypted monitoring; when the target operating condition characteristic energy value is greater than the alarm threshold, it triggers alarm processing and generates a shutdown command or an audible and visual alarm command. The control and protection module is connected to the multi-source signal acquisition module and the fault judgment module respectively, executes the shutdown command or the audible and visual alarm command, and monitors the safety status during the test process; The signal processing module includes a link compensation unit, an angular domain synchronization unit, and a filtering and noise reduction unit; the link compensation unit is used to parse the link status word, extract the lost signal segments, and output the vibration acceleration signal after temperature compensation and repair. The angular domain synchronization unit is used to analyze the instantaneous rotational speed, obtain the time interval corresponding to the preset target angular domain resolution, and output the clock frequency control word to the hardware sampling clock to generate the angular domain vibration acceleration signal. The filtering and noise reduction unit is used to analyze the angular domain vibration acceleration signal, distinguish the background noise frequency band and the fault characteristic frequency band, extract the filter coefficients corresponding to the current rotation speed as dynamic filter coefficients, and output the filtered angular domain vibration acceleration signal to the vibration energy calculation module. The vibration energy calculation module is configured to perform energy smoothing on the filtered angular domain vibration acceleration signal within a preset number of crankshaft rotation cycles, and to weight it in combination with the historical state energy average read from the memory to generate a target working condition characteristic energy value for characterizing the degree of transient mechanical vibration energy anomaly. The fault diagnosis module includes a pre-stored baseline threshold table, which records the average background energy, standard deviation of background energy, and alarm coefficient used to control alarm sensitivity under different speed conditions. The background energy threshold corresponds to the mean background energy. The alarm threshold is the sum of the products of the mean background energy, the standard deviation of the background energy, and the alarm coefficient. When the rate of change of the target operating condition characteristic energy value is greater than or equal to the preset mutation rate, and the duration is greater than or equal to the preset judgment period, the fault judgment module will forcibly switch the current state to the alarm processing state.

[0018] This embodiment presents the overall working mode of an internal combustion engine fault testing system based on vibration signal extraction. Within one system cycle, the system synchronously acquires vibration acceleration signals, crankshaft pulse signals, and ambient temperature signals through a multi-source signal acquisition module. The signal processing module in the computing node first completes link status discrimination, compensation and repair, and angular domain synchronization. Then, the angular domain vibration acceleration signal is filtered according to the speed variation. The vibration energy calculation module generates the target operating condition characteristic energy value. The fault judgment module provides the results of conventional monitoring, encrypted monitoring, or alarm processing according to the threshold range. Finally, the control and protection module implements the shutdown command or audible and visual alarm command. With this processing order, the input signal does not directly enter the threshold judgment without preprocessing. Instead, it first ensures the consistency of time, amplitude, and operating conditions before entering the fault judgment. Therefore, it can reduce misjudgments caused by strong background noise, speed fluctuations, and link anomalies. In a practical implementation, the multi-source signal acquisition module can consist of a vibration sensor, a crankshaft encoder, a temperature sensor, and a data acquisition interface connected to them. Vibration acceleration signal, crankshaft pulse signal and ambient temperature signal are written into the local buffer of the computing node through the corresponding sampling channels; The local buffer is preferably an on-chip memory or a cache area, used to store the original sampled values, timestamps and channel status bits of each channel within the same system cycle; The link status word can be generated synchronously by the interface control logic when writing to the buffer. It at least reflects whether the channel has lost packets, whether the timestamps are continuous, and whether there is an alignment deviation. Since the data from each channel first enters a unified buffer and is then read by the signal processing module according to the same system cycle, the common problem of mismatch between the preceding and following cycles when processing each signal independently is avoided. The system acquires vibration acceleration signals, crankshaft pulse signals, and ambient temperature signals. Based on the integrity monitoring results of each data channel, it performs unified buffering and link determination on the signals and generates link status words. Among them, the link status word refers to the status information that characterizes whether the data link can be directly used for fault analysis within the current system cycle, such as normal reception, timestamp drift, and short-term packet loss; This implementation method incorporates channel time offset and micro-circuit packet loss, which are easily overlooked, into the pre-judgment conditions through unified caching and synchronization judgment, so that subsequent processing is no longer based on missing data. This implementation method can filter the original data entry based on unified link determination, avoid abnormal channels from directly participating in fault identification, and ultimately overcome the technical defects of existing technologies that lead to an increase in false triggers due to the lack of a link health judgment mechanism. Furthermore, after reading the link status word, the link compensation unit in the signal processing module first determines whether there are signal loss segments or time alignment deviations in the current window; If the link status word indicates that the current window is complete, the original vibration acceleration signal directly enters the angular domain synchronization unit; if the link status word indicates that there is an anomaly, temperature compensation and data interpolation repair are performed first. Temperature compensation is used to correct the amplitude attenuation caused by impedance drift of piezoelectric sensors and cables under high-temperature environments; Data interpolation repair is used to fill in the short segment missing caused by micro-circuit; the repaired data is rewritten back to the valid sampling area in the aforementioned local buffer, and the original abnormal flag is still retained in the status bit for subsequent protection logic to call; Obtain the link status word, and perform temperature compensation and data interpolation repair on the vibration acceleration signal according to the anomaly type indicated by the link status word to generate a repaired vibration acceleration signal; Among them, signal loss segment refers to the gap in a continuous sampling sequence where no valid data is formed, such as the absence of several consecutive sampling points; temperature compensation refers to the correction of amplitude attenuation caused by high temperature; and data interpolation repair refers to the estimation of missing samples based on valid samples before and after the gap. This implementation method incorporates ambient temperature, an actual operating condition quantity, into the compensation process, so that the repair result takes into account both data interpolation and amplitude calibration, and transforms the amplitude nonlinear distortion caused by high temperature into a quantifiable and correctable numerical compensation parameter. This implementation method can achieve abnormal link repair based on temperature-related compensation, avoid amplitude distortion caused by simple interpolation, and ultimately solve the technical defect of existing technology that the repair data cannot be used for judgment due to the lack of temperature correction mechanism. Furthermore, the angular domain synchronization unit calculates the instantaneous rotational speed based on the crankshaft pulse signal and updates the hardware sampling clock accordingly; The crankshaft pulse signal can be converted into the current instantaneous speed after the pulse interval is recorded by the capture register at the encoder input terminal; By directly applying the instantaneous rotational speed to the hardware sampling clock, the sampling point corresponds to the crankshaft angle, thus preventing the waveform from being stretched or compressed in the angular domain and the fault characteristic frequency band drift caused by fixed-time sampling under varying operating conditions. The action is applied to the hardware sampling clock, causing the analog-to-digital converter trigger frequency to adjust with the rotational speed, thereby forming angular domain vibration acceleration signals with equal angular intervals at the source; The clock frequency control word is obtained as follows: a preset target angular domain resolution is set to limit the crankshaft angle between two adjacent sampling points. Its value can be set according to the resolution requirements of the fault frequency band, for example, it can be selected as a preset angle step size. Let the current instantaneous rotational speed be used to represent the crankshaft's rotational speed per minute under the current operating conditions; then the current instantaneous angular velocity can be calculated from the instantaneous rotational speed according to the circumferential arc relationship; based on this, the time interval required to rotate through the preset target angular domain resolution can be obtained by dividing the preset target angular domain resolution by the angular rate per second corresponding to the current instantaneous rotational speed, and the clock frequency control word output to the hardware sampling clock register can be obtained, which is the reciprocal of the time interval; The clock frequency control word is used to directly rewrite the target frequency value of the hardware sampling clock register so that the analog-to-digital converter can trigger sampling at equal angles at the current rotation speed; Since the rotational speed is contained within the molecule, the sampling frequency increases synchronously with the increase of the rotational speed, thereby ensuring dynamic adaptive adjustment on the time axis; if the change in rotational speed within an adjacent system cycle does not exceed the update threshold, the previous control word is maintained to avoid frequent register overwriting that could cause sampling jitter. The crankshaft pulse signal is acquired, and the hardware sampling clock is adjusted according to the instantaneous speed conversion relationship to generate angular domain vibration acceleration signals with equal angular intervals. Among them, equal angular interval means that adjacent sampling points maintain a fixed interval on the crankshaft angle, for example, using the same preset angle as the step, rather than maintaining a fixed interval in physical time; This implementation directly maps instantaneous rotational speed to a clock frequency control word, captures the true correspondence between angular domain positions under rotational speed fluctuations, and transforms phase distortion caused by time domain instability into controllable angular domain equal-interval sampling. This implementation can achieve angular domain synchronization based on hardware clock adaptive adjustment, avoiding order drift caused by fixed-time sampling, and ultimately solving the technical defect of unstable fault characteristics caused by the lack of angular domain reference in the existing technology. Furthermore, the filtering and noise reduction unit does not use a fixed filter, but extracts the corresponding filter coefficients from the pre-stored parameter table according to the current rotation speed as dynamic filter coefficients; The background noise frequency band includes combustion background noise and mechanical background noise, and the fault characteristic frequency band is the frequency range related to minor faults such as bearing peeling and piston ring micro-wear. After the dynamic filter coefficients are obtained by looking up a table, they are written into the filter coefficient buffer register in the field programmable gate array or digital signal processor. During the filter update, the system can temporarily block the fault output through the protection logic, and allow energy calculation after the filter stabilizes. The filtered angular domain vibration acceleration signal is written into the energy calculation buffer. After the buffer is read, the corresponding data page is released to maintain continuous window processing. The calculation process for the filtered angular domain vibration acceleration signal is as follows: taking the angular domain position corresponding to the current crankshaft rotation angle as the reference point, extracting multiple original angular domain vibration acceleration sampling points covering the filter order range before the reference point to form the filtered input sequence for the current point; Extract a set of filter tap coefficients corresponding to the current instantaneous rotation speed from the pre-existing parameter table, and use them as the weights for each input sampling point; The weighted product terms are summed to output the filtered angular domain vibration acceleration signal at the current reference point position, which is used for subsequent energy calculation. By performing point-to-point multiplication and addition operations with rotational speed-related weights, background frequency bands are suppressed and fault characteristic frequency bands are preserved in a targeted manner according to operating conditions. The angular domain vibration acceleration signal is acquired, and the angular domain vibration acceleration signal is filtered according to the filter coefficients corresponding to the current rotational speed to generate the filtered angular domain vibration acceleration signal. Among them, the dynamic filter coefficient refers to the filter parameters selected as the current speed changes. For example, different tap coefficients correspond to low speed conditions and high speed conditions. Its function is to match the filter range with the actual noise distribution. This implementation method updates the coefficients by looking up a table according to the rotational speed, and implements targeted suppression of the background noise frequency band, while maintaining a high passability of the fault characteristic frequency band, so that weak features are no longer weakened by the strong background. This implementation method can achieve noise reduction processing adapted to operating conditions based on the speed-related filter coefficient, avoid the mismatch of fixed filters under varying operating conditions, and ultimately solve the technical defect of the prior art that weak fault characteristics are easily submerged by noise due to the lack of an adaptive filtering mechanism. Furthermore, the vibration energy calculation module generates characteristic energy values ​​of the target working condition according to the process; its first step is to square the filtered angular domain vibration acceleration signal point by point to obtain the single-point energy value; The second step is to divide the current crankshaft rotation cycle based on the crankshaft pulse signal, and to accumulate all the single-point energy values ​​within the cycle to obtain the total energy of a single cycle; The third step is to perform a sliding average on the sum of the energy of a single cycle within a window containing a preset number of crankshaft rotation cycles to obtain the average energy of the window. The fourth step is to read the historical average energy value from the preset memory, and then perform a weighted summation according to the preset weighting coefficient to generate the target working condition characteristic energy value. The default memory is a local non-volatile storage area used to store the average energy value under previous stable operating conditions or recent healthy conditions; The preset weighting coefficient is used to balance the influence of the current window energy and the historical energy on the results. Its value can be set according to the sensitivity requirements for sudden anomalies. For example, the current window can be given a higher weighting coefficient to make it more sensitive to new anomalies. The filtered angular domain vibration acceleration signal is obtained. Based on the crankshaft rotation period division results, the signal is squared, periodically accumulated, windowed moving average, and historically weighted to generate the target working condition characteristic energy value. Among them, the average energy of the window refers to the result of smoothing the sum of the energy of a single cycle within a range of multiple consecutive crankshaft rotation cycles, such as the average energy covering several consecutive working cycles, while the average energy of the historical state refers to the reference energy level stored in the preset memory. This implementation method extracts stable anomalies and weakens occasional spikes by compressing and weighting them layer by layer through single point, single period, window, and history, thereby suppressing false alarms caused by transient impact noise. This implementation method can calculate the characteristic energy value of the target working condition based on multi-layer energy aggregation, avoiding the judgment distortion caused by excessive single-point vibration, and ultimately solving the technical defect of unstable judgment caused by the lack of a joint measurement mechanism of period and history in the existing technology. Furthermore, the fault diagnosis module has a built-in benchmark threshold table; this benchmark threshold table pre-stores the background energy mean, background energy standard deviation and alarm coefficient according to different speed conditions; the background energy threshold directly corresponds to the background energy mean, and is used to distinguish between normal background and transitional states that require intensive monitoring. The alarm threshold is determined according to the following rules: obtain the pre-calibrated average healthy background energy under the current speed condition to characterize the reference energy level of the normal state at that speed; The corresponding background energy standard deviation is extracted to characterize the degree of dispersion of allowable fluctuations under normal conditions; the fluctuation margin is obtained by multiplying the background energy standard deviation by the alarm coefficient, which is used as a factor to amplify the control alarm sensitivity. Finally, the fluctuation margin is superimposed with the average healthy background energy to generate the alarm threshold at that speed. After comparing the current target operating condition characteristic energy value with the background energy threshold and the alarm threshold, three types of processing results can be obtained: when it is less than the background energy threshold, routine monitoring is performed. Encrypted monitoring is performed when the value is between two thresholds; alarm processing is triggered when the value is greater than the alarm threshold; if the rate of change of the target working condition characteristic energy value is greater than the preset mutation rate and the duration is greater than the preset judgment period, the alarm processing state can be forcibly switched even if the accumulated energy is still in the middle range, so as to respond to the sudden deterioration of the working condition in a timely manner. The characteristic energy values ​​of the target operating condition are obtained, and the characteristic energy values ​​of the target operating condition are compared and the rate of change is determined according to the benchmark threshold table to determine the operating state of the internal combustion engine. Among them, the background energy threshold refers to the upper limit of the normal background range, such as the average energy level of the health machine at the corresponding speed; the alarm threshold refers to the trigger boundary for entering fault handling; and the preset mutation rate refers to the judgment condition when the energy change rate is greater than the preset threshold. This implementation uses a combination of graded thresholds and mutation rate to make judgments, enabling the system to identify both slow deterioration and rapid instability within a short period, thus transforming the contradiction between late alarms and early alarms into a layered processing approach. This implementation can achieve state-level output based on rotational speed-related threshold and rate of change determination, avoiding insufficient sensitivity or excessive false alarms of fixed thresholds under wide operating conditions, and ultimately solving the technical defect of inaccurate judgment caused by the lack of operating condition-based threshold mechanism in the existing technology. Compared with conventional testing mechanisms that use fixed-time sampling, fixed filters, and fixed thresholds, under high-speed heavy-load and rapidly changing speed conditions, fault characteristics are often superimposed with background vibrations. Especially when a strong combustion background is present, simply increasing the sampling rate or increasing the alarm threshold can only create a trade-off between false alarms and missed alarms. This implementation first filters out abnormal windows based on the link status word, then generates an angular domain signal based on the instantaneous rotation speed, and calls different filtering coefficients and corresponding thresholds for different rotation speeds. Therefore, it is easier to maintain the stability of the characteristic frequency band position, the energy statistics range, and the alarm boundary under similar extreme working conditions. Therefore, this implementation method is not a simple splicing of existing processing links, but rather incorporates link status, rotation speed, temperature and vibration amplitude into the same processing flow. In actual deployment, the aforementioned multi-source signal acquisition module, signal processing module, vibration energy calculation module, fault judgment module, and control and protection module can be arranged in the computing node close to the sensor; The newly acquired vibration acceleration signal, crankshaft pulse signal and ambient temperature signal enter the local buffer through their respective sampling channels. After processing, only the target operating condition characteristic energy value, status word and alarm result are retained for continuous judgment. Once the fault diagnosis module outputs a shutdown command or an audible and visual alarm command, the control and protection module changes the state of the corresponding control bit through the hardware output interface, driving the external programmable logic controller or relay to perform the shutdown or alarm action, thus forming a complete implementation process from acquisition, processing, judgment to execution.

[0019] In a preferred embodiment of the present invention, after the alarm processing is triggered, the following operations are performed: record the speed parameters and temperature parameters of the current internal combustion engine test state; switch the acquisition mode of the multi-source signal acquisition module and increase the sampling frequency of the vibration acceleration signal of the abnormal channel indicated by the link status word; Record the status data at the time of the alarm, and extract the compensation status at the time of the alarm and the version number of the filter parameter corresponding to the current dynamic filter coefficient; Save the abnormal state type determined based on the target operating condition characteristic energy value, as well as the abnormal channel number indicated by the link status word, as the basis for generating subsequent diagnostic reports; The control and protection module has a built-in multi-level protection mechanism; the first level of protection is synchronous verification protection. When the time alignment error between the data channels of the multi-source signal acquisition module is greater than or equal to the preset alignment threshold, the current alarm judgment logic is frozen and only the retest data is uploaded. The second level of protection is the filter switching buffer protection. When the operating condition switch causes the filter coefficient to be updated, the fault judgment output is blocked within the transition buffer window. The third level of protection is continuous over-limit shutdown protection. When the energy value of the target operating condition is detected to be continuously greater than or equal to the alarm threshold and reaches or exceeds the preset number of rotation cycles, a high-level signal is forcibly output through the hardware interface to trigger the external programmable logic controller or relay to perform shutdown. The system also includes a host computer management module; the host computer management module is used to automatically record the data of the entire process from the start to the end of the test. The data of the entire process includes basic characteristic parameters, characteristic energy data, link anomaly statistics logs and judgment instruction logs. The host computer management module has built-in report templates that can automatically generate standardized reports containing test conditions, process summaries, key parameter curves, and status conclusions based on the recorded data.

[0020] When the aforementioned fault judgment module determines that the energy value of the target operating condition characteristic exceeds the alarm threshold, or meets the conditions of change rate and duration period, the system does not end by simply outputting an alarm signal, but continues to perform alarm data preservation, acquisition mode switching, protection shielding and report generation. This process ensures that alarm results can trigger on-site actions in a timely manner and also provide traceable evidence for subsequent diagnosis and retesting. Obtain alarm trigger results, record parameters, switch acquisition modes, and save abnormal information for the current test conditions based on the alarm status, and generate alarm record data; Among them, alarm record data refers to a set of information directly related to this alarm, such as the speed parameters, temperature parameters, compensation status, abnormal channel number and filter parameter version number at the time of the alarm. This set of information is used to trace back the conditions under which the fault occurred. This implementation method synchronously solidifies key operating conditions and processing parameters after an alarm is triggered, so that the alarm result is no longer just a simple status bit, but can correspond to specific operating conditions, specific channels and specific parameter versions. This implementation method can track and record abnormal events based on data preservation after an alarm, avoiding the lack of working condition information after an alarm occurs, and ultimately solving the technical defect of the existing technology that makes subsequent diagnosis difficult due to the lack of an event recording mechanism. In practice, after the fault judgment module outputs the alarm processing signal, the control logic first reads the speed parameters and temperature parameters from the current processing cache. The speed parameter corresponds to the instantaneous speed or representative speed within the alarm window, and the temperature parameter corresponds to the ambient temperature within the same window. The system locates the abnormal channel based on the link status word and writes a new acquisition mode control word to the multi-source signal acquisition module to increase the sampling frequency of the vibration acceleration signal of the abnormal channel. The control word can be written through the configuration register of the acquisition module. After writing, the new sampling configuration will take effect in subsequent system cycles. By limiting high-frequency sampling to the abnormal channel, transient waveform features such as local spikes and short-term impact segments around the fault trigger point can be extracted while maintaining the system bus bandwidth utilization. Furthermore, in addition to the original operating conditions, the status data at the time of the alarm also includes the compensation status at the time of the alarm and the version number of the filter parameter corresponding to the current dynamic filter coefficient. The compensation status indicates whether the alarm window data has undergone link compensation processing, thus distinguishing between the original direct sampling alarm and the compensated alarm; the filter parameter version number identifies the source of the filter parameters corresponding to this alarm, facilitating subsequent report tracking and parameter revision; The above data can be packaged and written to the alarm log area corresponding to the host computer management module, or it can be written to the local non-volatile buffer first and then read periodically by the host computer; after saving the abnormal status type and abnormal channel number, the system has the minimum evidence set required to generate a diagnostic report; The time alignment error of the data channel is obtained, and the alarm judgment logic is frozen according to the preset alignment threshold to generate a synchronization verification protection result. Among them, time alignment error refers to the time deviation of sampling data from different channels within the same system cycle, such as the offset between timestamps. Freeze alarm judgment logic means that the current window is temporarily not allowed to participate in alarm output, and only the retest data upload is retained. This implementation method prioritizes pausing the judgment when the time alignment deviation is greater than the preset alignment threshold, so that the fundamental problem of channel asynchrony is isolated first, and false anomalies are avoided after misaligned data splicing. This implementation method can achieve abnormal window isolation based on synchronous verification protection, avoid false alarms caused by multi-channel time drift, and ultimately solve the technical defect of existing technology that leads to result distortion due to the lack of channel synchronous gating mechanism. In practical implementation, the first level of protection is synchronous verification protection; the control protection module reads the timestamps of each channel from the acquisition buffer and calculates the time alignment error; When the error exceeds the preset alignment threshold, the control and protection module will clear the enable bit corresponding to the current alarm judgment logic and mark this window as a retest window. The raw data, link status words, and operating condition summaries within the retest window can be uploaded via the host computer interface without participating in the local alarm output; this ensures that alarm judgment is based on time-aligned valid data. Obtain the filter coefficient update status, and based on the operating condition switching result, perform transition buffering and shielding on the fault judgment output to generate the filter switching buffer protection result; The transition buffer window refers to the stable interval after the filter coefficients switch from the old value to the new value. For example, it is a number of processing windows during the period when the old and new coefficients alternate. The data in this interval is only used for filter stabilization and not for alarm determination. This implementation adds a buffer shield during operating condition switching to prevent changes in the filter response from being mistakenly identified as mechanical abnormalities. This implementation can achieve decision isolation during parameter switching based on filter switching buffer protection, avoid the introduction of false features by hot coefficient updates, and ultimately solve the technical defect of the prior art that leads to more misjudgments due to the lack of a transition window mechanism. In practice, the second level of protection is the filter switching buffer protection; as long as the angle domain synchronization unit determines that the rotation speed has entered a new parameter range, the filter noise reduction unit will read the new filter coefficients from the parameter table and write them into the coefficient register. Within the transition window after the coefficient register is updated, the output shield bit of the fault judgment module is set to invalid; only when the buffer count meets the preset conditions is the new filtering result allowed to enter the vibration energy calculation module and the fault judgment module; thus avoiding the identification of the filter's transition response as a fault impact when the operating conditions are switched. The system obtains the continuous over-limit results of the characteristic energy value of the target working condition, controls the output status of the hardware interface according to the preset number of rotation cycles, and generates a shutdown high-level signal. Among them, continuous over-limit refers to the target working condition characteristic energy value being greater than the alarm threshold in multiple consecutive crankshaft rotation cycles. The preset number of rotation cycles is used to limit the shutdown action from being triggered by a single occasional over-limit. This implementation method performs secondary confirmation under continuous over-limit conditions, ensuring that the shutdown action is both timely and not overly sensitive. This implementation method can achieve hardware-level shutdown output based on continuous over-limit shutdown protection, avoiding direct shutdown triggered by instantaneous interference, and ultimately overcoming the technical defects of the prior art, which suffers from low shutdown control accuracy due to the lack of continuity criteria. In practical implementation, the third level of protection is continuous over-limit shutdown protection; the control protection module maintains an over-limit counter that is updated according to the crankshaft rotation cycle. When the target operating condition characteristic energy value is detected to be continuously greater than the alarm threshold and reaches the preset number of rotation cycles, a high-level signal is forcibly output through the hardware interface. The high-level signal can be sent to an external programmable logic controller or relay input through the digital output port to trigger a shutdown; if the continuous cycle condition is not met, the system will only maintain alarm recording and audible and visual alarm output, and will not execute a shutdown. Furthermore, the host computer management module is used to automatically record data throughout the entire process; the data throughout the entire process includes at least basic characteristic parameters, characteristic energy data, link anomaly statistics logs, and judgment instruction logs; the basic characteristic parameters may include rotational speed, temperature, and main vibration amplitude within each system cycle; The characteristic energy data corresponds to the target working condition characteristic energy value output by the vibration energy calculation module; the link anomaly statistics log corresponds to the cumulative anomaly of the link status word in multiple system cycles; the judgment command log corresponds to the trigger records of routine monitoring, encrypted monitoring, alarm processing, and shutdown commands. The host computer management module has a built-in report template. After the experiment, it can automatically read the above logs and recorded data to generate a standardized report that includes the test conditions, process summary, key parameter curves and status conclusions. Compared to conventional test systems that only output a single alarm signal, their recording mechanism lacks data related to operating conditions, making it impossible to explain under what operating conditions the alarm occurred or whether there was link compensation and filtering switching before the alarm. Conventional system status records lack temporal correlation dimensions, so during subsequent retesting, only re-experiments can be conducted, making it impossible to pinpoint the processing stage where the problem occurred. This implementation method synchronously records the speed parameters, temperature parameters, compensation status, abnormal channel number, and filter parameter version number after an alarm. It also adds three layers of constraints to the protection module: synchronous verification, filter switching buffer, and continuous over-limit shutdown. Therefore, it retains the on-site action capability and improves the verifiability of the results. In actual deployment, the host computer management module can periodically read the structured data frames output by the computing node through the communication interface, and create corresponding log files or report caches according to the test tasks; Whenever the control and protection module outputs a shutdown command or an audible and visual alarm command, the host computer management module synchronously refreshes the judgment command log and key parameter curves; After the test is completed, the report template automatically retrieves all the data from the process, generates a standardized report, and makes it available for testers to view; thus achieving an automated closed-loop processing of test data from acquisition, alarm, protection to report output.

[0021] In a preferred embodiment of the present invention, the link compensation unit is configured to determine the temperature difference between the current ambient temperature corresponding to the ambient temperature signal and the reference calibration temperature, and to determine a temperature compensation coefficient reflecting the degree of thermal drift based on the temperature difference, so as to correct the amplitude attenuation of the vibration acceleration signal caused by high temperature. The angular domain synchronization unit is configured to determine and output the target clock frequency for controlling the hardware sampling clock based on the set target angular domain resolution and instantaneous rotation speed. The host computer management module is also used to analyze historical test data, distinguish historical test data at specific speeds, distinguish the combustion background noise frequency band and the mechanical background noise frequency band at specific speeds, use noise separation methods to separate background noise from fault signals, calculate filter coefficients based on the maximum signal-to-noise ratio of the target fault frequency band, and then send the filter coefficients to the signal processing module as the basis for extracting dynamic filter coefficients for real-time updates.

[0022] The ambient temperature signal is acquired, and the vibration acceleration signal is temperature compensated based on the difference between the current ambient temperature and the reference calibration temperature to generate a vibration acceleration signal after temperature compensation and repair. Among them, the current ambient temperature refers to the temperature measurement value corresponding to the current abnormal window, the reference calibration temperature refers to the reference temperature used when the sensor or cable is in the calibration state, and the temperature drift ratio refers to the degree of thermal drift corresponding to the difference between the two. This embodiment determines the compensation coefficient by temperature drift ratio, so that the compensation intensity is adjusted with temperature change, thereby improving the actual situation of sensor amplitude attenuation under high temperature environment; this embodiment can realize vibration signal amplitude correction based on temperature drift ratio, avoid the effective feature being too small due to high temperature, and finally solve the technical defect of amplitude distortion caused by lack of temperature correlation compensation mechanism in the prior art. In practice, the link compensation unit first reads the ambient temperature signal within the current system cycle and calculates the difference between it and the reference calibration temperature to obtain the temperature drift ratio; this ratio is used to represent the degree of deviation of the current temperature from the calibration temperature. The link compensation unit determines the temperature compensation coefficient based on the temperature drift ratio and multiplies the compensation coefficient with the vibration acceleration signal to correct the signal amplitude attenuation caused by high temperature. If there is a short-term packet loss in the current window, the missing segments can be interpolated and repaired first, and then the same temperature compensation coefficient can be applied to the repaired samples to maintain a consistent amplitude benchmark before and after compensation. The temperature compensation coefficient is used to recover the response decrease caused by impedance drift of sensors and cables under high temperature conditions, without changing the angular domain structure and period division results of the vibration signal; Furthermore, when a more explicit compensation calculation method is required, this implementation method generates the temperature compensation coefficient according to the following data flow rules: by reading the upper limit of the sensor's allowable operating temperature range and performing a difference calculation between it and the reference calibration temperature, the temperature range span is obtained; The ambient temperature deviation is obtained by subtracting the current ambient temperature of the window where the sample to be repaired is located from the reference calibration temperature. The ambient temperature deviation is then divided by the temperature range span to calculate the temperature drift ratio, which reflects the degree of deviation of the current temperature from the normalization of the calibration temperature. Based on this, a thermal drift sensitivity coefficient is introduced to control the effect of temperature changes on the compensation intensity. This sensitivity coefficient is multiplied by the temperature drift ratio, and its exponential function value is calculated with the natural constant as the base, ultimately generating the temperature compensation coefficient. The specific formula for calculating this temperature compensation coefficient is as follows:

[0023]

[0024] in, This is the temperature compensation coefficient. This is the thermal drift sensitivity coefficient. This represents the temperature drift ratio; After applying the temperature compensation coefficient to the vibration acceleration signal, the signal amplitude after temperature correction can be obtained; for short missing samples, it can also be reconstructed by combining the previous valid samples to form a compensated estimate. The preset target angular domain resolution and instantaneous rotation speed are obtained. Based on the conversion relationship between the two, the clock frequency control word is calculated and written into the hardware sampling clock register to generate the angular domain sampling control result. Among them, the preset target angular domain resolution refers to the angular step corresponding to each sampling point. For example, each sampling point covers a preset fixed angle, and the clock frequency control word refers to the target frequency value written into the hardware sampling clock register. This implementation method directly adjusts the triggering rhythm from the hardware sampling entry point, so that the sampling points meet the angular domain equal interval requirement when they are generated, instead of correcting them in the post-processing stage. This implementation can achieve hardware clock control based on the conversion between target angular domain resolution and instantaneous rotation speed, avoiding interpolation errors caused by subsequent resampling, and ultimately solving the technical defect of unstable sampling reference caused by the lack of hardware-level angular domain synchronization mechanism in the existing technology. In practical implementation, the angular domain synchronization unit first calculates the instantaneous speed based on the crankshaft pulse signal, and then calculates the clock frequency control word in a certain way; Let the preset target angular resolution be The current instantaneous rotational speed is Then the current instantaneous rotation speed is reduced by The required time interval is ,Will The reciprocal of the frequency is converted to the target clock frequency and written to the hardware sampling clock register; To facilitate hardware implementation, the clock frequency control word can first be mapped to a numerical register in the computing node, and then written to the analog-to-digital converter timer register via the bus; After the register is rewritten, the subsequent sampling trigger frequency will be operated according to the new control word; if the speed change within an adjacent window is not significant, the existing register value will not be overwritten to reduce sampling jitter caused by frequent switching; Furthermore, when specifically calculating the target clock frequency, the result is equal to the instantaneous rotational speed multiplied by a constant six and then divided by the degree value corresponding to the preset target angular resolution; the formula for calculating the target clock frequency is:

[0025]

[0026] in, The target clock frequency, in units of ; Instantaneous rotational speed, unit: ; The preset target angular resolution is expressed in units of 1000 Å. ; The structured calculation relationship shows that the target clock frequency increases linearly with the instantaneous rotational speed. The preset target angular domain resolution controls the sampling angle resolution capability; the smaller the value, the more sampling points are within a unit rotation angle. The instantaneous rotational speed reflects the rotational speed of the current operating condition. The target clock frequency obtained directly determines the sampling rhythm of the analog-to-digital converter under the current operating conditions. Since this frequency value is written into the hardware register, this quantity is not the result of the abstract algorithm, but a control parameter that actually acts on the sampling circuit. Acquire historical test data, calculate and distribute filter coefficients based on noise separation results at specific speeds, and generate a dynamic filter parameter table; Among them, historical test data refers to the full-process data continuously recorded by the host computer management module, combustion background noise frequency band refers to the background vibration components related to the combustion process, mechanical background noise frequency band refers to the background vibration components related to normal mechanical operation, and the maximum signal-to-noise ratio condition of the target fault frequency band means that the obtained filter coefficients should make the energy of the fault frequency band as prominent as possible relative to the energy of the noise frequency band. This implementation method distinguishes background noise from different sources by analyzing historical test data, and then calculates the filter coefficients based on the condition that the signal-to-noise ratio of the target fault frequency band is the maximum, so that the filter parameters are matched with the specific model and specific speed range. This implementation method can realize dynamic calculation and distribution of filtering parameters based on historical data analysis, avoiding mismatch of fixed empirical parameters under complex working conditions, and ultimately solving the technical defect of unstable filtering effect caused by lack of parameter update basis in the existing technology. In practice, the host computer management module continuously saves data from the start to the end of the test, and selects historical test data of the same model, similar working conditions and different speed ranges for analysis. During the analysis, the combustion background noise frequency band and the mechanical background noise frequency band at a specific speed are first distinguished, and then the noise separation method is used to separate the background noise from the fault signal. Based on this, the filter coefficients are calculated with the maximum signal-to-noise ratio of the target fault frequency band as the condition. This maximization condition is achieved through the following energy ratio optimization rule: First, within the angular domain, the amplitude squares of the angular domain signal components in the filtered fault frequency band are summed to obtain the sum of the energy characterizing the fault features to be retained. Simultaneously, the amplitude squared and accumulated components of the angular domain signal in the filtered background noise frequency band are summed to obtain the sum of the energy of the background components that need to be suppressed as much as possible. The ratio is obtained by dividing the sum of the energy of the fault features by the sum of the energy of the background components, and then converting it into a logarithmic energy ratio to characterize the signal-to-noise ratio. The values ​​of each tap coefficient are iteratively adjusted using an optimization algorithm to maximize the logarithmic energy ratio. The set of tap coefficients that converges at this point is taken as the filter coefficients. After the calculation is completed, the host computer management module organizes the filter coefficients into a dynamic filter parameter table according to the speed range, and attaches a parameter version number. This parameter table is sent to the signal processing module via the communication interface, and the signal processing module updates it in real time as the basis for extracting dynamic filtering coefficients during real-time processing. In the existing technology, if the link compensation only uses a fixed amplification factor, the angular domain synchronization only relies on post-processing interpolation, and the filtering parameters only rely on manual experience to set, then when high temperature, variable speed and strong background noise coexist, the three steps will have problems such as large amplitude repair deviation, unstable sampling reference and mismatch of filtering parameters, respectively. This implementation method uses the temperature drift ratio to determine the compensation coefficient, uses the target angular domain resolution and instantaneous rotation speed to generate the hardware clock control word, and uses historical test data to calculate the dynamic filter parameter table. Therefore, the processing basis is directly related to the actual working conditions and is suitable for continuous use in complex test environments. During application implementation, the host computer management module can first complete the filter coefficient calculation and version organization based on the accumulated historical test data, and then send the corresponding parameter table to the calculation node; In the new round of testing, the computing node reads the ambient temperature signal and crankshaft pulse signal, and performs temperature compensation and clock frequency control word update respectively; when the new real-time data enters the filtering and noise reduction unit, it selects the corresponding filter coefficients according to the issued parameter table for processing. If new alarm records and full-process data are generated during the test, the host computer management module can continue to save these data for subsequent recalculation or revision of dynamic filtering parameters; in this way, the actual deployment process from parameter preparation, real-time execution to result feedback can be completed.

[0027] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A fault testing system for internal combustion engines based on vibration signal extraction, characterized in that, include: The multi-source signal acquisition module synchronously acquires vibration acceleration signals, crankshaft pulse signals, and ambient temperature signals during the operation of the internal combustion engine, monitors the integrity of the multiple data channels connected, and generates link status words. The signal processing module performs temperature compensation and data interpolation repair based on the link status word, calculates the instantaneous rotational speed based on the crankshaft pulse signal and adjusts the hardware sampling clock, generates angular domain vibration acceleration signals with equal angular intervals, and extracts dynamic filtering coefficients corresponding to the current rotational speed to filter the angular domain vibration acceleration signals. The vibration energy calculation module calculates the characteristic energy value of the target working condition by combining the instantaneous rotational speed, the dynamic filtering coefficient, and the signal amplitude of the filtered angular domain vibration acceleration signal. The fault diagnosis module has a built-in background energy threshold and alarm threshold. When the target operating condition characteristic energy value is less than the background energy threshold, it performs regular monitoring; when the target operating condition characteristic energy value is greater than or equal to the background energy threshold and less than or equal to the alarm threshold, it performs encrypted monitoring; when the target operating condition characteristic energy value is greater than the alarm threshold, it triggers alarm processing and generates a shutdown command or an audible and visual alarm command. The control and protection module is connected to the multi-source signal acquisition module and the fault judgment module respectively, executes the shutdown command or the audible and visual alarm command, and monitors the safety status during the test process; The signal processing module includes a link compensation unit, an angle domain synchronization unit, and a filtering and noise reduction unit. The link compensation unit is used to parse the link status word, extract the lost signal segments, and output the vibration acceleration signal after temperature compensation and repair. The angular domain synchronization unit is used to analyze the instantaneous rotational speed, obtain the time interval corresponding to the preset target angular domain resolution, and output a clock frequency control word to the hardware sampling clock to generate the angular domain vibration acceleration signal. The filtering and noise reduction unit is used to analyze the angular domain vibration acceleration signal, distinguish between background noise frequency band and fault characteristic frequency band, extract the filter coefficients corresponding to the current rotational speed as the dynamic filtering coefficients, and output the filtered angular domain vibration acceleration signal to the vibration energy calculation module. The control and protection module has a built-in multi-level protection mechanism; The first level of protection is synchronous verification protection. When the time alignment error between the data channels of the multi-source signal acquisition module is greater than or equal to the preset alignment threshold, the current alarm judgment logic is frozen and only the retest data is uploaded. The second level of protection is the filter switching buffer protection. When the operating condition switch causes the filter coefficient to be updated, the fault judgment output is blocked within the transition buffer window. The third level of protection is continuous over-limit shutdown protection. When the energy value of the target operating condition characteristic is detected to be continuously greater than or equal to the alarm threshold and reaches or exceeds the preset number of rotation cycles, a high-level signal is forcibly output through the hardware interface to trigger an external programmable logic controller or relay to perform shutdown. The link compensation unit is configured to determine the temperature difference between the current ambient temperature corresponding to the ambient temperature signal and the reference calibration temperature, and to determine a temperature compensation coefficient reflecting the degree of thermal drift based on the temperature difference, so as to correct the amplitude attenuation of the vibration acceleration signal caused by high temperature. The angular domain synchronization unit is configured to determine and output a target clock frequency for controlling the hardware sampling clock based on the set target angular domain resolution and the instantaneous rotation speed. The system also includes a host computer management module; The host computer management module is used to automatically record the data of the entire process from the start of the test to the end of the test. The data of the entire process includes basic characteristic parameters, characteristic energy data, link anomaly statistics log and judgment instruction log. The host computer management module has a built-in report template that can automatically generate standardized reports containing test conditions, process summaries, key parameter curves, and status conclusions based on the recorded data. The host computer management module is also used to analyze historical test data, distinguish historical test data at specific speeds, distinguish the combustion background noise frequency band and the mechanical background noise frequency band at specific speeds, use a noise separation method to separate the background noise from the fault signal, calculate the filter coefficients based on the maximum signal-to-noise ratio of the target fault frequency band, and then send the filter coefficients to the signal processing module as the basis for extracting the dynamic filter coefficients for real-time updates.

2. The internal combustion engine fault testing system based on vibration signal extraction according to claim 1, characterized in that, The vibration energy calculation module is configured to perform energy smoothing on the filtered angular domain vibration acceleration signal within a preset number of crankshaft rotation cycles, and to weight it in combination with the historical state energy average read from the memory to generate the target working condition characteristic energy value used to characterize the degree of transient mechanical vibration energy anomaly.

3. The internal combustion engine fault testing system based on vibration signal extraction according to claim 1, characterized in that, The fault judgment module includes a pre-stored benchmark threshold table, which records the average background energy, standard deviation of background energy, and alarm coefficient for controlling alarm sensitivity under different speed conditions. The background energy threshold corresponds to the average background energy. The alarm threshold is the sum of the products of the mean background energy, the standard deviation of the background energy, and the alarm coefficient; When the rate of change of the target operating condition characteristic energy value is greater than or equal to the preset mutation rate, and the duration is greater than or equal to the preset judgment period, the fault judgment module will forcibly switch the current state to the alarm processing state.

4. The internal combustion engine fault testing system based on vibration signal extraction according to claim 1, characterized in that, After the alarm is triggered, the following operations are performed: Record the speed and temperature parameters of the internal combustion engine under the current test conditions; Switch the acquisition mode of the multi-source signal acquisition module to increase the sampling frequency of the vibration acceleration signal of the abnormal channel indicated by the link status word; Record the status data at the time of the alarm, and extract the compensation status at the time of the alarm and the version number of the filter parameter corresponding to the current dynamic filter coefficient; Save the abnormal state type determined based on the target operating condition characteristic energy value, and the abnormal channel number indicated by the link status word, as the basis for generating subsequent diagnostic reports.

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