A method and system for phase alignment of reciprocating machinery vibration signals

Abstract

The application discloses a reciprocating mechanical vibration signal phase alignment method and system, comprising: under the condition of having a timing reference signal, synchronously collecting vibration signals and crank angle signals at multiple preset measuring points; selecting a group of continuous vibration signals collected under stable working conditions for band-pass filtering, phase correction, resampling, envelope amplitude extraction, and single-period envelope sequence generation, thereby obtaining a reference envelope; under the condition of not having a timing reference signal, synchronously collecting vibration data to be aligned; intercepting a data segment of one working cycle, and sequentially performing band-pass filtering, resampling, and envelope amplitude extraction to obtain an envelope sequence to be aligned; calculating a cross-correlation coefficient of the shifted envelope sequence and the reference envelope to determine a phase offset; and translating the vibration data to be aligned according to the phase offset, so that the starting point of the translated signal corresponds to a zero-phase reference defined by the reference envelope, and outputting the vibration signal after phase alignment.

Description

Technical Field

[0001] This invention relates to the interdisciplinary field of non-stationary signal processing, electromechanical equipment vibration analysis, and intelligent state perception, specifically to a method and system for phase alignment of reciprocating mechanical vibration signals based on envelope matching. The method and system are applicable to the operational status analysis, working process analysis, health status monitoring, and fault diagnosis and location of hybrid power systems, generators, compressors, plunger pumps, precision components, and other reciprocating and rotary composite motion equipment. Background Technology

[0002] Vibration signal analysis is a crucial technical means for monitoring the operating status, evaluating performance, and diagnosing faults in electromechanical equipment. For reciprocating generators, reciprocating compressors, plunger pumps, and other reciprocating-rotational machinery with periodic motion characteristics, the vibration response generated during operation contains rich information about the mechanism's motion and load variations. By analyzing the periodic and impact characteristics in the vibration signals, objectives such as identifying the operating status of electromechanical equipment, monitoring its health, and diagnosing and locating faults can be achieved.

[0003] For reciprocating-rotational cyclic motion machinery, the amplitude information of vibration signals alone is insufficient to accurately reflect the operating status of the equipment. For example, mechanical events such as valve opening and closing, piston reversal, and mechanical collisions in crank-connecting rod mechanisms all occur in specific working phases. Without phase information, vibration characteristics cannot be correlated with specific mechanical events, and in-phase comparisons between different working cycles are impossible, severely limiting the depth of vibration signal analysis. Therefore, establishing a phase correspondence between vibration signals and the working cycles of electromechanical equipment is crucial.

[0004] However, the vibration characteristics of such machinery are closely related to specific operating phases. For example, events such as valve opening and closing, piston reversal, and mechanical collisions in crank-connecting rod mechanisms all occur at specific crankshaft rotation angles. Without phase information, vibration characteristics cannot be correlated with specific mechanical events, and in-phase comparisons between different operating cycles are impossible, severely limiting the depth of vibration signal analysis.

[0005] CN120609444A provides a signal acquisition method, apparatus, device, and storage medium. Based on the envelope curve of a first vibration signal of the cylinder head of a first cylinder in a dual-cycle angular domain, and a first valve timing table for reciprocating machinery, the first envelope energy of multiple impacts of the reciprocating machinery is determined. Based on the envelope curve and a second valve timing table that lags behind the target angle relative to the first valve timing table, the second envelope energy of these multiple impacts is determined. Based on the relationship between the first total energy and the second total energy, the occurrence of phase drift is determined, where the first total energy is the sum of all first envelope energies, and the second total energy is the sum of all second envelope energies. Based on this occurrence, a single-cycle second vibration signal is extracted from the first vibration signal. Thus, accurate cylinder head angular domain full-cycle signals can be obtained. Although this patent involves relative positioning, it heavily relies on key phase sensors and preset valve timing tables. This method increases the cost and workload of hardware deployment, installation, debugging, and subsequent maintenance. Furthermore, for modern highly integrated equipment, its ECU relies on timing signals for fuel injection and ignition control. External test leads may interfere with ECU signal stability. To address this issue, the industry has proposed a phase alignment method without angle sensors, but it still has the following shortcomings: Image-based corner-domain segmentation requires converting the signal into an image, determining the period through similarity search, and then calculating the phase shift using impact recognition and a thermodynamic model. This method is highly dependent on the clarity of the impact features and has poor robustness. Time-domain signal method: It requires the synchronous acquisition of multi-dimensional signals such as acceleration, velocity, displacement and cylinder pressure, which has stringent requirements for sensor configuration and high hardware costs. Deep learning methods require a large amount of labeled data for pre-training, and have weak generalization ability across different models and test points, resulting in high costs for model transfer and deployment.

[0006] In summary, there is an urgent need for a lightweight, low-cost, robust phase alignment method that does not require additional timing hardware. Summary of the Invention

[0007] This invention addresses the shortcomings of existing technologies by providing a method and system for phase alignment of vibration signals in reciprocating machinery. The phase alignment method utilizes only the vibration signal itself for phase identification, eliminating the need for dual-channel fusion or complex vector-mode calculations.

[0008] The first aspect of this invention is to provide a method for phase alignment of reciprocating mechanical vibration signals, comprising: Step 1: Under the condition of having a timing reference signal, simultaneously collect vibration signals and crankshaft angle signals at multiple preset measuring points of the reciprocating machine; wherein the reciprocating machine operates under at least one set of steady-state conditions; Step 2: Select a set of continuous vibration signals under stable operating conditions collected in Step 1 and perform bandpass filtering. Use the crankshaft angle signal to identify the working cycle boundary and extract the periodic segments of each cycle. Using the action phase of a specific mechanical event as the zero phase reference, perform phase correction on the periodic segments according to the installation phase deviation of the timing reference signal. Resample the corrected periodic segments based on the preset angle resolution, extract the envelope amplitude of each phase point to generate a single-cycle envelope sequence, and average the single-cycle envelope sequences of all complete working cycles to obtain the reference envelope. Step 3: In the absence of a timing reference signal, at the preset measurement points of the reciprocating machine under test, the vibration data to be aligned is synchronously acquired using the same acquisition device as in Step 1; the vibration data to be aligned without a timing signal is received in real time, and the number of sampling points contained in a single complete working cycle is calculated based on the operating speed and sampling rate corresponding to the vibration data, and a data segment of one working cycle is extracted, and the bandpass filtering, resampling based on the preset angle resolution, and envelope amplitude extraction steps of Step 2 are executed in sequence to obtain the envelope sequence to be aligned; the envelope sequence to be aligned is cyclically shifted with respect to the reference envelope obtained in Step 2, and the cross-correlation coefficient between the sequence obtained after each shift and the reference envelope is calculated; after traversing all shift positions, the shift frequency corresponding to the peak value of the correlation coefficient is determined as the phase offset; and the vibration data to be aligned is translated according to the phase offset so that the starting point of the translated signal corresponds to the zero phase reference defined by the reference envelope, and the phase-aligned vibration signal is output.

[0009] In one embodiment, the preset measuring points of the reciprocating motion machine include at least the first cylinder head, the fifth cylinder block, and the sixth cylinder head, and an acceleration sensor is respectively installed on each of the preset measuring points; the crankshaft angle signal is acquired using a photoelectric encoder installed at the crankshaft end.

[0010] Furthermore, it also includes sending the phase-aligned vibration signal to the diagnostic module to perform operational status analysis, working process analysis, health status monitoring, and fault diagnosis and location.

[0011] Furthermore, in step one, the resolution of the photoelectric encoder is 256 pulses / revolution; the sampling frequency of the vibration signal is 51.2kHz.

[0012] Furthermore, in step one, the steady-state operating condition is selected from any one of multiple parameter combinations covering speeds from 650 rpm to 1900 rpm and loads from 0% to 100%; when constructing the reference envelope, continuous vibration data under a single steady-state operating condition is selected for processing.

[0013] Furthermore, step two specifically includes: A set of continuous vibration signals under specific steady-state conditions collected in step one are selected and bandpass filtered. Using the pulse sequence output by the photoelectric encoder as the trigger source, a trigger threshold is set, and the falling edge of the pulse signal is used as the starting boundary of the period. The period boundary is identified and multiple single-period signal segments are extracted. Define the action phase of a specific mechanical event as the zero-phase reference, and perform cyclic shift correction on each single-cycle signal segment based on the deviation between the installation phase of the photoelectric encoder and the zero-phase reference to unify the starting phase of each cycle; The phase-corrected signal segments are reshaped and resampled to a fixed angular resolution so that each signal segment corresponds to the same number of phase points. For each phase point, half of the extreme value difference of its corresponding sampling point is extracted as the envelope amplitude to generate a single-cycle envelope sequence; The single-cycle envelope sequences corresponding to multiple work cycles are averaged to obtain a reference envelope characterizing the features of a typical work cycle.

[0014] Furthermore, step three involves performing a full-cycle cyclic shift on the envelope sequence to be aligned, including: Set the number of shift steps The range of values ​​is: ;in The number of points corresponding to the angular resolution; For the Each shift position is used to align the vibration signal envelope sequence. Perform a cyclic shift to generate the shifted sequence: in, This represents the cyclic shift operator.

[0015] A second aspect of the present invention is to provide a phase alignment system for reciprocating mechanical vibration signals, comprising: The reference signal acquisition module is used to arrange acceleration sensors at multiple preset measuring points on the body of the reciprocating motion machine and install a photoelectric encoder at the crankshaft end; under at least one set of steady-state operating conditions, the vibration signal and crankshaft rotation angle signal are acquired synchronously. The reference envelope generation module is used to bandpass filter the continuous vibration signal acquired by the reference signal acquisition module, identify the working cycle boundary using the crankshaft angle signal, and extract the periodic segments of each cycle; using the action phase of a specific mechanical event as the zero phase reference, the periodic segments are phase corrected according to the installation phase deviation of the timing reference signal; the corrected periodic segments are resampled based on a preset angle resolution, the envelope amplitude of each phase point is extracted to generate a single-cycle envelope sequence, and the single-cycle envelope sequences of all complete working cycles are averaged to obtain the reference envelope; The signal acquisition module is used to synchronously acquire vibration data to be aligned at preset measurement points of the reciprocating machine under test in the absence of a timing reference signal. The acquisition device is the same model as the reference signal acquisition module and the same preset measurement point position is used. The signal processing module calculates the number of sampling points in a single complete working cycle based on the vibration data acquired by the signal acquisition module under the corresponding operating conditions, speed, and sampling rate, and extracts a data segment of one working cycle. It then inputs the data into the reference envelope generation module, performs bandpass filtering, resampling, and calculates the envelope amplitude at each phase point to obtain the envelope sequence to be aligned. The module performs a full-cycle cyclic shift on the envelope sequence to be aligned, calculates the cross-correlation coefficient between the sequence obtained after each shift and the reference envelope, and after traversing all shift positions, determines the shift step number corresponding to the peak correlation coefficient as the phase offset. Based on the phase offset, it translates the vibration data to be aligned so that the starting point of the translated signal corresponds to the zero-phase reference defined by the reference envelope, and outputs the phase-aligned vibration signal.

[0016] The beneficial effects of this invention are as follows: The phase alignment method uses only the vibration signal itself for phase identification, without relying on dual-channel fusion or complex vector mode calculations. The phase alignment method uses a photoelectric encoder only in the offline stage of constructing the reference envelope in step one, and does not rely on any hardware timing signal in the online real-time alignment stage. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the data acquisition setup for step one of the reciprocating motion mechanical vibration signal phase alignment method described in this invention; Figure 2 This is a flowchart of the phase alignment method described in this invention; Figure 3 This is a schematic diagram of envelope correlation matching and phase alignment in step three of the phase alignment method described in this invention; Figure 4These are verification results of the phase alignment method described in this invention; wherein (a) shows a schematic diagram of the signal amplitude of the vibration signal to be aligned and the reference envelope of the first accelerometer channel using the method described in this invention; (b) shows a schematic diagram of the signal amplitude of the vibration signal to be aligned and the reference envelope of the second accelerometer channel using the method described in this invention; and (c) shows a schematic diagram of the signal amplitude of the vibration signal to be aligned and the reference envelope of the third accelerometer channel using the method described in this invention.

[0018] Wherein, 1: first cylinder; 2: second cylinder; 3: third cylinder; 4: fourth cylinder; 5: fifth cylinder; 6: sixth cylinder; 7: cylinder head; 8: shock absorber housing; 9: photoelectric encoder; 10: first acceleration sensor; 11: second acceleration sensor; 12: third acceleration sensor. Detailed Implementation

[0019] To make the objectives, technical solutions, beneficial effects, and significant advancements of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings provided in the examples of the present invention. Obviously, all 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.

[0020] In the description of this application, unless otherwise expressly specified and limited, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more; unless otherwise specified or explained, the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0021] like Figure 2 As shown, a method for phase alignment of reciprocating mechanical vibration signals includes: Step 1: Experiment Setup and Data Acquisition like Figure 1As shown, this embodiment is implemented in a six-cylinder engine bench test system, which includes a first cylinder 1, a second cylinder 2, a third cylinder 3, a fourth cylinder 4, a fifth cylinder 5, and a sixth cylinder 6. To obtain the vibration response, a first acceleration sensor 10 is installed on the cylinder head of the first cylinder 1, a second acceleration sensor 11 is installed on the cylinder block of the fifth cylinder 5, and a third acceleration sensor 12 is installed on the cylinder head of the sixth cylinder 6. All three acceleration sensors are piezoelectric acceleration sensors. Furthermore, a photoelectric encoder 9 with a resolution of 256 pulses / revolution is installed at the crankshaft end as a timing reference.

[0022] To obtain accurate timing reference signals (i.e., crankshaft angle information), an optical encoder 9 is installed at the free end of the crankshaft. In this embodiment, the optical encoder 9 selected has a resolution of 256 pulses / revolution, which can provide high-precision speed and phase references.

[0023] Multiple steady-state operating conditions are set within the speed range of 650-1900rpm and the load range of 0-100%, so that the engine operates under multiple steady-state operating conditions. The vibration signals of the three acceleration sensors and the crankshaft speed signal of the photoelectric encoder 9 are collected simultaneously. The vibration signal sampling frequency is set to 51.2kHz.

[0024] Figure 1 The signal acquisition module includes multiple data acquisition cards and a data acquisition card integration framework. The data acquisition card receives analog signal input from the sensor, converts it into a digital signal, and then transmits it to the host computer or edge computing device through the Ethernet (TCP / IP) network communication protocol for subsequent processing.

[0025] Step 2: Reference Envelope Construction Using vibration data with photoelectric encoder timing marks collected in step one under a steady-state condition for multiple consecutive working cycles, a reference envelope characterizing the working cycle features of the electromechanical equipment is constructed. This provides a unified reference standard for subsequent phase alignment of vibration signals. In this embodiment, continuous vibration data under a specific condition is selected from the multiple sets of steady-state operating conditions collected in step one for processing. The specific construction process is as follows: S21: Select the set of continuous vibration signals under steady-state conditions (950 rpm, 443.3 Nm) collected in step one as the data source, and process the original discrete vibration signals... Bandpass filtering is performed to remove low-frequency trend terms and high-frequency noise, retaining the effective frequency bands that include characteristics such as valve seating and combustion impact. (1) in, The vibration signal is after bandpass filtering. This represents the bandpass filter operator. This represents the original discrete vibration signal.

[0026] S22: Utilizing the pulse sequence output by photoelectric encoder 9 As a trigger source, set a trigger threshold. Find the falling edge of the pulse signal as the starting boundary of the period. Record the set of boundary indices of all falling edges in the vibration signal. For the first Each period, the original fragment extracted based on the index set is denoted as . : (2) in, For the first The actual sample length of each period; m represents the index of the sampling point within the data segment, and satisfies .

[0027] S23: Define the zero-phase reference and correct the starting point of each cycle based on the installation phase deviation. To unify the physical meaning, a specific mechanical event action phase is defined as the zero-phase reference. In this embodiment, the firing action phase of the sixth cylinder 6 is taken as the zero-phase reference. Based on the installation phase of the photoelectric encoder 9 and the aforementioned zero-phase reference, there is a mechanical event action phase deviation. Calculate the number of sampling points that need to be shifted. : (3) 720° is the angle corresponding to one engine cycle.

[0028] Correcting the installation phase difference through cyclic shifting operations: (4) in, This represents a cyclic shift operator that appends the cut-off portion of the signal back to the end of the signal.

[0029] S24: Set the angle resolution and use Sinc interpolation to reshape and resample each cyclic signal obtained in S23.

[0030] The corrected signal is reshaped so that the number of signal points can be accommodated by a preset angular resolution. Divide to obtain reshaping and signal. : (5) in, It is the Sinc interpolation convolution operator. After reshaping, its length is equal to the angular resolution. Integer multiples of.

[0031] The signal to be reshaped Mapped to the angular resolution To obtain a signal containing phase information : (6) in, It is a resampling operator. The number of sampling points contained in each phase.

[0032] S25: Calculate the envelope amplitude at each angle point and take the average value to generate a stable reference envelope.

[0033] For each phase The amplitude of the envelope of a phase is taken as half the difference between the maximum and minimum values ​​in the corresponding set of sampling points, thus characterizing the vibration energy intensity under that phase. : (7) After traversing all phase points, the first phase point is obtained. The envelope sequence corresponding to each working cycle : (8) S26: Average the envelope sequences corresponding to all complete working cycles to obtain the reference envelope. : (9) Thus, the reference envelope is obtained. Where N is the number of working cycles. The reference envelope... It reflects the typical vibration envelope characteristics of the engine within one working cycle under this operating condition, and does not depend on the random error of a single sampling.

[0034] Step 3: As Figure 3 As shown, the reference envelope obtained in step two is used. Phase identification and correction are performed on vibration data to be aligned that lacks a timing signal. The specific implementation process is as follows.

[0035] S31: Preprocessing and envelope extraction of the signal to be aligned.

[0036] Acceleration sensors are also installed on the electromechanical equipment to be tested at the cylinder head of the first cylinder (1), the cylinder block of the fifth cylinder (5), and the cylinder head of the sixth cylinder (6). The equipment used in steps one and three is the same model to avoid vibration differences caused by equipment differences. The photoelectric encoder 9 is not installed here.

[0037] During the operation of the electromechanical equipment, analog voltage signals from acceleration sensors located on the cylinder heads of the first cylinder 1, the fifth cylinder 5, and the sixth cylinder 6 are continuously received via the ADC interface and converted into digital raw vibration signals. The raw vibration signals are written into a first-in-first-out (FIFO) circular data buffer in real time. The status of the buffer is continuously monitored to ensure that the latest vibration data, which is sufficient to cover at least one complete working cycle, is always held.

[0038] Based on the operating speed of 950 rpm corresponding to the collected data and the vibration sensor sampling rate of 51.2 kHz, combined with the mechanical characteristic that "a complete working cycle contains two revolutions", the number of sampling points contained in a single complete working cycle is calculated as follows: Then, based on the calculation result, a data segment of a complete work cycle is extracted.

[0039] For the original vibration signal to be aligned that lacks phase information and is acquired in step three, perform bandpass filtering using equation (1) from step two, reshape and resample the bandpass filtered signal using equations (5)-(6), and calculate the envelope amplitude at each angle point using equations (7)-(8) to obtain the envelope sequence corresponding to the alignment work cycle: (10) S32: Since the initial sampling position (i.e., initial phase) of the vibration signal to be aligned is unknown, its envelope sequence With reference envelope There is a phase shift between them. To find the optimal phase matching point, the envelope sequence of the vibration signals to be aligned is... Perform a circular shift: (11) in, This represents a cyclic shift operator; Indicates the number of shift steps; .

[0040] For the Given a shift position, calculate the shifted sequence. With reference envelope Pearson correlation coefficient between : (12) in: The mean of the reference envelope; This is the mean of the shifted sequence.

[0041] S33: After traversing all shift positions, a sequence of correlation coefficients is obtained. The peak position is found in the correlation coefficient sequence; this peak position is in phase with the reference envelope. The number of shift steps corresponding to the peak position is the phase offset of the vibration signal envelope to be aligned relative to the reference envelope. Based on the calculated phase offset, the vibration signal to be aligned is phase-shifted. After phase shifting, the vibration signal to be aligned is aligned with the reference envelope. The defined zero-phase reference strictly corresponds to the unified phase reference, thus achieving phase alignment.

[0042] After the phase shifting process described above, the phase-aligned vibration signal is output. At this point, the phase-aligned vibration signal establishes a unified phase reference with the zero-phase reference, completing the phase alignment. The characteristic impacts in the signal can then be precisely mapped to specific crankshaft rotation angles, providing a reliable data foundation for subsequent condition monitoring and fault diagnosis.

[0043] Step 4: Use the phase-aligned output vibration signal to perform operational status analysis, refined analysis of the working process, health status monitoring, and fault diagnosis and location.

[0044] At the same time, the system clears the temporary cache, returns to step two, and continues to read the next frame of data from the ADC interface, forming an uninterrupted online real-time processing closed loop; thus, without relying on physical timing hardware, it continuously provides vibration data support with accurate phase information for the intelligent operation and maintenance of reciprocating-rotating machinery.

[0045] Steps two and three of the phase alignment method described in this embodiment are solidified into standardized reference envelope generation and signal processing modules using a programming language. The reference envelope generation module for step two and the signal processing module for step three are directly deployed on the target hardware platform to achieve online monitoring and intelligent diagnosis of reciprocating-rotational cyclic motion machinery throughout its entire lifecycle. Step two, as a pre-calculation step, has its calculation results serialized into a program-readable data file (e.g., .npy format) for direct import and use by the signal processing module for step three. The target hardware platform includes, but is not limited to, a mechanical operation test platform, a vehicle control unit (VCU) or generator control unit (GCU) for hybrid vehicles.

[0046] like Figure 4As shown, the phase alignment method described in this invention is verified. First, under the condition of having a timing reference signal, analog acceleration sensor signals from three measuring points—the cylinder head of cylinder 1 (first cylinder), the cylinder block of cylinder 5 (fifth cylinder), and the cylinder head of cylinder 6 (sixth cylinder)—are simultaneously acquired and converted into digital raw vibration signals. These three digital signals are then input to the reference envelope generation module corresponding to step two. The module calculates and generates the reference envelope for each channel, and serializes the reference envelope into a program-readable data file for storage, to be used in subsequent phase alignment.

[0047] Subsequently, with the timing reference signal removed, the analog acceleration sensor signals from the three identical measurement points were acquired again and converted into digital raw vibration signals. These three digital raw vibration signals without timing, along with the previously stored reference envelope data file, were imported into the signal processing module described in step three. This module automatically calculates the phase offset based on the imported data and performs phase correction on the raw vibration signals, thereby achieving phase alignment of the multi-channel signals.

[0048] Figure 4 Figures (a), (b), and (c) illustrate the alignment of vibration signals with the reference envelope under three different sensor channels. As shown in the figures, the impact peak positions of the vibration signals in each channel highly coincide with the peak positions of the reference envelope in the crankshaft rotation domain. Verification results demonstrate that the method described in this invention can effectively achieve phase alignment of vibration signals under conditions without a timing reference.

[0049] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for phase alignment of reciprocating mechanical vibration signals, characterized in that, include: Step 1: Under the condition of having a timing reference signal, simultaneously collect vibration signals and crankshaft angle signals at multiple preset measuring points of the reciprocating machine; wherein the reciprocating machine operates under at least one set of steady-state conditions; Step 2: Select a set of continuous vibration signals under stable operating conditions collected in Step 1 and perform bandpass filtering. Use the crankshaft angle signal to identify the working cycle boundary and extract the periodic segments of each cycle. Using the action phase of a specific mechanical event as the zero phase reference, perform phase correction on the periodic segments according to the installation phase deviation of the timing reference signal. Resample the corrected periodic segments based on the preset angle resolution, extract the envelope amplitude of each phase point to generate a single-cycle envelope sequence, and average the single-cycle envelope sequences of all complete working cycles to obtain the reference envelope. Step 3: Under conditions where a timing reference signal is unavailable, at the preset measurement points of the reciprocating machine under test, the vibration data to be aligned is synchronously acquired using the same acquisition device as in Step 1. The vibration data to be aligned without a timing signal is received in real time. Based on the rotational speed and sampling rate corresponding to the vibration data, the number of sampling points included in a single complete working cycle is calculated, and a data segment of one working cycle is extracted. The bandpass filtering, resampling based on a preset angular resolution, and envelope amplitude extraction steps from Step 2 are executed sequentially to obtain the envelope sequence to be aligned. The envelope sequence to be aligned is cyclically shifted throughout its entire cycle relative to the reference envelope obtained in Step 2. The cross-correlation coefficient between the sequence obtained after each shift and the reference envelope is calculated. After traversing all shift positions, the shift frequency corresponding to the peak correlation coefficient is determined as the phase offset. The vibration data to be aligned is translated according to the phase offset so that the starting point of the translated signal corresponds to the zero-phase reference defined by the reference envelope, and the phase-aligned vibration signal is output.

2. The method for phase alignment of reciprocating mechanical vibration signals according to claim 1, characterized in that, The phase alignment method also includes steps of performing operational status analysis, working process analysis, health status monitoring, and fault diagnosis and location on the phase-aligned vibration signal.

3. The method for phase alignment of reciprocating mechanical vibration signals according to claim 1, characterized in that, In step one, an acceleration sensor is set at each of the preset measuring points; the crankshaft angle signal is obtained using a photoelectric encoder installed at the crankshaft end.

4. The method for phase alignment of reciprocating mechanical vibration signals according to claim 1, characterized in that, In step one, the steady-state operating condition is selected from any one of multiple parameter combinations covering speeds from 650 rpm to 1900 rpm and loads from 0% to 100%; when constructing the reference envelope, continuous vibration data under a single steady-state operating condition is selected for processing.

5. The method for phase alignment of reciprocating mechanical vibration signals according to claim 1, characterized in that, Step two specifically includes: A set of continuous vibration signals under specific steady-state conditions collected in step one is selected and bandpass filtered. Using the pulse sequence output by the photoelectric encoder as the trigger source, a trigger threshold is set, and the falling edge of the pulse signal is used as the starting boundary of the period. The period boundary is identified and multiple single-period signal segments are extracted. Define the action phase of a specific mechanical event as the zero-phase reference, and perform cyclic shift correction on each single-cycle signal segment based on the deviation between the installation phase of the photoelectric encoder and the zero-phase reference to unify the starting phase of each cycle; The phase-corrected signal segments are reshaped and resampled to a fixed angular resolution so that each signal segment corresponds to the same number of phase points. For each phase point, half of the extreme value difference of its corresponding sampling point is extracted as the envelope amplitude to generate a single-cycle envelope sequence; The single-cycle envelope sequences corresponding to multiple work cycles are averaged to obtain a reference envelope characterizing the features of a typical work cycle.

6. The method for phase alignment of reciprocating mechanical vibration signals according to claim 1, characterized in that, Step three involves performing a full-cycle cyclic shift on the envelope sequence to be aligned, including: Set the number of shift steps The range of values ​​is: ;in The number of points corresponding to the angular resolution; For the Each shift position is used to align the vibration signal envelope sequence. Perform a cyclic shift to generate the shifted sequence: in, This represents the cyclic shift operator.

7. A phase alignment system for reciprocating mechanical vibration signals, characterized in that, include: The reference signal acquisition module is used to arrange acceleration sensors at multiple preset measuring points on the body of the reciprocating motion machine and to install a photoelectric encoder at the crankshaft end; Under at least one set of steady-state operating conditions, vibration signals and crankshaft angle signals are collected synchronously. The reference envelope generation module is used to bandpass filter the continuous vibration signal acquired by the reference signal acquisition module, identify the working cycle boundary using the crankshaft angle signal, and extract the periodic segments of each cycle; using the action phase of a specific mechanical event as the zero phase reference, the periodic segments are phase corrected according to the installation phase deviation of the timing reference signal; the corrected periodic segments are resampled based on a preset angle resolution, the envelope amplitude of each phase point is extracted to generate a single-cycle envelope sequence, and the single-cycle envelope sequences of all complete working cycles are averaged to obtain the reference envelope; The signal acquisition module is used to synchronously acquire vibration data to be aligned at preset measurement points of the reciprocating machine under test in the absence of a timing reference signal. The acquisition device is the same model as the reference signal acquisition module and the same preset measurement point position is used. The signal processing module calculates the number of sampling points included in a single complete working cycle based on the vibration data collected by the signal acquisition module and the corresponding operating speed and sampling rate, and extracts a data segment of a working cycle. Input the reference envelope generation module, perform bandpass filtering, resampling, and calculate the envelope amplitude at each phase point to obtain the envelope sequence to be aligned; Perform a full-cycle cyclic shift on the envelope sequence to be aligned, and calculate the cross-correlation coefficient between the sequence obtained after each shift and the reference envelope; After traversing all shift positions, the number of shift steps corresponding to the peak value of the correlation coefficient is determined as the phase offset. The vibration data to be aligned is translated according to the phase offset so that the starting point of the translated signal corresponds to the zero phase reference defined by the reference envelope, and the phase-aligned vibration signal is output.

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