A method for detecting compressor shaft wear based on acceleration and displacement sensors

Abstract

A method for detecting compressor shaft wear based on acceleration and displacement sensors belongs to the field of vehicle testing technology. Acceleration and displacement sensors are deployed in zones and marked for positioning. Vibration and displacement signals are collected using ETAS ES650 and INCA software. Raw data is collected under a unified thermal equilibrium condition, and vibration characteristics are extracted after 10-point moving average filtering. Using data after equipment maintenance as a benchmark, the slope of vibration parameter changes is linearly fitted to determine progressive wear; a single peak exceeding the benchmark by 50% is identified as a foreign object or broken tooth, and cross-verification is performed. This invention balances ease of detection, data comparability, and fault early warning capabilities, enabling stable and low-cost routine online monitoring of compressor shaft wear in environmental compartments. It overcomes the shortcomings of existing methods involving shutdown disassembly and oil analysis, which are complex to operate and lack predictive capabilities.

Description

Technical Field

[0001] This invention belongs to the field of vehicle testing technology, specifically a method for detecting wear on compressor shafts based on acceleration and displacement sensors. Background Technology

[0002] In vehicle testing, environmental control using an environmental chamber is an indispensable step. The environmental chamber uses two industrial compressors for temperature control; however, prolonged use can lead to wear and tear on some compressor components. Wear on critical compressor parts, such as bearings, over time can cause minor issues like decreased compressor efficiency, excessively high operating temperatures, and compressor seizure. More serious problems can result in compressor breakage, hot lubricating oil splashing, and other safety accidents, posing a severe threat to testing personnel, valuable equipment, and the testing environment, and introducing significant safety risks and uncertainties to the research and development process. To prevent such failures, current methods for inspecting internal compressor wear typically involve:

[0003] 1. Shaft center trajectory and shaft displacement monitoring: An eddy current sensor is directly pointed at the shaft to measure its position and movement trajectory within the bearing. After wear, the shaft center trajectory becomes larger and more divergent, and the static shaft displacement will also deviate from the reference.

[0004] 2. Lubricating oil analysis: Regularly sample the lubricating oil circuit and use spectral analysis and ferrography to analyze the metal particles in the oil. This can provide early warning and also roughly determine whether the wear is on the shaft itself or the bearing alloy.

[0005] 3. Industrial endoscope and dial indicator inspection: After shutdown, insert the endoscope through the oil filler port, oil drain port, or sensor mounting hole to directly observe whether there are scratches or grooves on the surface of the shaft journal. At the same time, use a dial indicator or feeler gauge to measure the radial runout of the shaft and the bearing clearance. However, existing methods are too complex and require specialized knowledge; untrained testing personnel cannot operate them.

[0006] The three traditional detection methods mentioned above also have the problem of not being able to solidify the uniform operating conditions. The compressor temperature, power, and lubricating oil condition are different each time the test is conducted. The data collected before and after are discrete and disordered, and can only make a static judgment on the degree of wear in a single test, but cannot quantify the wear development rate. At the same time, single eddy current displacement monitoring can only obtain shaft offset data, lacking vibration characteristics to assist in the verification, and the accuracy of wear identification is limited.

[0007] Therefore, there is an urgent need to develop a simple and convenient method for detecting wear on the internal shaft of a compressor. This method should be able to clearly show whether there is wear on the internal shaft of the compressor, collect data over a long period of time under uniform operating conditions, quantify the rate of wear deterioration, accurately identify potential risks before a failure occurs, contain the failure in its infancy, and ensure that the test is safe and controllable. Summary of the Invention

[0008] To address the problems existing in the background art, the present invention provides a method for detecting compressor shaft wear based on acceleration and displacement sensors.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: a method for detecting compressor shaft wear based on acceleration and displacement sensors, comprising the following steps:

[0010] S1: Sensor positioning and installation;

[0011] S2: Signal acquisition link setup;

[0012] S3: Data acquisition under standard operating conditions;

[0013] S4: Data preprocessing;

[0014] S5: Wear trend analysis and judgment.

[0015] S1 includes:

[0016] S101: The acceleration sensor is attached and fixed to the rear bearing of the compressor, and the displacement sensor is installed separately on the compressor mounting bracket. The two types of sensors are arranged in corresponding zones.

[0017] S102: Set permanent marks at the respective installation points of the accelerometer and displacement sensor to ensure that both types of sensors are installed at the corresponding marked positions during each test.

[0018] S2 includes:

[0019] S201: Establish a communication connection between the accelerometer, displacement sensor and host computer through the ETAS ES650 data acquisition device;

[0020] S202: Use a host computer equipped with INCA software to read and record the vibration and displacement signals output by the sensor in real time.

[0021] S3 includes:

[0022] S301: Manually control the environmental chamber compressor to operate under preset uniform standard conditions;

[0023] S302: After the operating conditions stabilize, start the host computer to begin data acquisition. After the acquisition is completed, save the original data under the corresponding operating conditions.

[0024] The specific pre-set unified standard operating condition in S301 is as follows: the initial temperature of the environmental chamber is set to -30℃, the main compressor is controlled to run at 50% of the rated power, the auxiliary compressor is kept off, and the operation is continued for 30 minutes until the actual temperature in the environmental chamber is stable at 30℃ and the compressor outlet pressure is stable at 30MPa before data collection is carried out; the data collection time in S302 is 5~10 minutes, and the operating condition is kept stable during the collection process.

[0025] S4 includes:

[0026] S401: Performs moving average filtering on the acquired raw acceleration and displacement signals to eliminate noise data caused by environmental interference;

[0027] S402: Extract the average values ​​of vibration frequency and vibration amplitude based on the filtered signal;

[0028] S403: Generate time-series curves from the preprocessed acceleration data and displacement amplitude data, where the frequency of positive and negative alternations per unit time of the acceleration curve corresponds to the actual vibration frequency of the compressor, and the peak value of the displacement amplitude curve corresponds to the vibration amplitude of the compressor.

[0029] In S401, the moving average filter is a 10-point moving average filter, and the sensor sampling frequency is set to 1kHz.

[0030] S5 includes:

[0031] S501: Under the same standard operating conditions as the first test, repeat S1-S4 regularly every day, and confirm that the sensor installation position is completely aligned with the permanent mark before each test;

[0032] S502: Compare the preprocessed data from each round with the baseline data;

[0033] S503: Using the detection date as the horizontal axis and the corresponding data as the vertical axis, a linear function is used for linear fitting to obtain the slope of the daily variation trend of vibration amplitude and vibration frequency.

[0034] S504: Determine the operating status of the compressor's internal shaft based on the slope obtained from the fitting.

[0035] In S502, the reference data is the initial data obtained by executing S1 to S5 and collecting and preprocessing according to the unified standard operating conditions in S301 after the compressor has completed shaft / bearing replacement or whole machine maintenance including shaft system.

[0036] In S504, the judgment rule is as follows: if the daily change slope of vibration amplitude is greater than 0.01 mm / day and / or the daily change slope of vibration frequency is greater than 0.01 Hz / day, if either parameter is satisfied, it is determined that the shaft is in rapid wear and needs to be repaired in time; if both slopes are less than or equal to the corresponding threshold, it is determined that the operating status is normal.

[0037] If the peak value of vibration frequency or peak value of vibration amplitude obtained in a single acquisition exceeds the initial reference value by 50%, it is determined that there is a sudden fault such as broken tooth or foreign object intrusion. The machine should be stopped immediately, and cross-verification should be completed by observation with an industrial endoscope, measurement of radial runout of the shaft with a dial indicator, or disassembly inspection.

[0038] Compared with the prior art, the beneficial effects of the present invention are:

[0039] 1. This invention uses accelerometers and displacement sensors deployed in zones to collect signals online, enabling compressor shaft wear monitoring without stopping or disassembling the machine. This does not occupy the downtime for environmental chamber testing and maintenance, thus improving the efficiency of continuous operation in vehicle testing.

[0040] 2. By standardizing the fixed thermal balance conditions, permanently marking sensor locations, and standardizing the acquisition and analysis process, data interference caused by temperature, lubricating oil status, and sensor installation deviations is eliminated. The detection data of each cycle can be compared longitudinally, solving the problems of discrete and disordered traditional detection data and difficulty in judging the wear development trend.

[0041] 3. The original vibration and displacement signals are processed by a 10-point moving average filter, which effectively filters out electromagnetic, airflow and resonance noise in the industrial field, and extracts stable vibration frequency and vibration amplitude quantification parameters, resulting in higher stability of the detection results.

[0042] 4. Set up a hierarchical fault judgment logic. Identify progressive wear by quantifying the wear deterioration rate through linear fitting slope, and identify sudden faults such as broken teeth and foreign object intrusion by single peak mutation. The hierarchical early warning can detect potential equipment problems in advance and reduce safety risks such as compressor jamming, casing damage, and lubricating oil splashing.

[0043] 5. The entire testing process is standardized and the judgment indicators are quantified, so operators do not need to have professional vibration diagnosis knowledge to complete the test; only two types of sensors are added and paired with the existing ETAS+INCA acquisition system, so the hardware modification investment is low and it is easy to use in batches for the modification of existing environmental chamber compressors.

[0044] In summary, this invention balances ease of detection, data comparability, and fault early warning capabilities, enabling stable and low-cost online monitoring of the wear of the environmental chamber compressor shaft. It overcomes the shortcomings of existing detection methods such as shutdown disassembly and oil analysis, which are complex to operate and lack predictive ability. Detailed Implementation

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0046] This embodiment describes a method for detecting compressor shaft wear based on acceleration and displacement sensors, including the following steps:

[0047] S1: Sensor positioning and installation;

[0048] S2: Signal acquisition link setup;

[0049] S3: Data acquisition under standard operating conditions;

[0050] S4: Data preprocessing;

[0051] S5: Wear trend analysis and judgment.

[0052] S1 includes:

[0053] S101: The acceleration sensor is attached and fixed to the rear bearing of the compressor, and the displacement sensor is installed separately on the compressor mounting bracket. The two types of sensors are arranged in corresponding zones.

[0054] S102: Set permanent marks at the respective installation points of the accelerometer and displacement sensor to ensure that both types of sensors are installed at the corresponding marked positions during each test.

[0055] S2 includes:

[0056] S201: Establish a communication connection between the accelerometer, displacement sensor and host computer through the ETAS ES650 data acquisition device;

[0057] S202: Use a host computer equipped with INCA software to read and record the vibration and displacement signals output by the sensor in real time.

[0058] S3 includes:

[0059] S301: Manually control the environmental chamber compressor to operate under preset uniform standard conditions;

[0060] S302: After the operating conditions stabilize, start the host computer to begin data acquisition. After the acquisition is completed, save the original data under the corresponding operating conditions.

[0061] The specific pre-set unified standard operating condition in S301 is as follows: the initial temperature of the environmental chamber is set to -30℃, the main compressor is controlled to run at 50% of the rated power, the auxiliary compressor is kept off, and the operation is continued for 30 minutes until the actual temperature in the environmental chamber is stable at 30℃ and the compressor outlet pressure is stable at 30MPa before data collection is carried out; the data collection time in S302 is 5~10 minutes, and the operating condition is kept stable during the collection process.

[0062] S4 includes:

[0063] S401: Performs moving average filtering on the acquired raw acceleration and displacement signals to eliminate noise data caused by environmental interference;

[0064] S402: Extract the average values ​​of vibration frequency and vibration amplitude based on the filtered signal;

[0065] S403: Generate time-series curves from the preprocessed acceleration data and displacement amplitude data, where the frequency of positive and negative alternations per unit time of the acceleration curve corresponds to the actual vibration frequency of the compressor, and the peak value of the displacement amplitude curve corresponds to the vibration amplitude of the compressor.

[0066] In S401, the moving average filter is a 10-point moving average filter, and the sensor sampling frequency is set to 1kHz.

[0067] S5 includes:

[0068] S501: Under the same standard operating conditions as the first test, repeat S1-S4 regularly every day, and confirm that the sensor installation position is completely aligned with the permanent mark before each test;

[0069] S502: Compare the preprocessed data from each round with the baseline data;

[0070] S503: Using the detection date as the horizontal axis and the corresponding data as the vertical axis, a linear function is used for linear fitting to obtain the slope of the daily variation trend of vibration amplitude and vibration frequency.

[0071] S504: Determine the operating status of the compressor's internal shaft based on the slope obtained from the fitting.

[0072] In S502, the reference data is the initial data obtained by executing S1 to S5 and collecting and preprocessing according to the unified standard operating conditions in S301 after the compressor has completed shaft / bearing replacement or whole machine maintenance including shaft system.

[0073] In S504, the judgment rule is as follows: if the daily change slope of vibration amplitude is greater than 0.01 mm / day and / or the daily change slope of vibration frequency is greater than 0.01 Hz / day, if either parameter is satisfied, it is determined that the shaft is in rapid wear and needs to be repaired in time; if both slopes are less than or equal to the corresponding threshold, it is determined that the operating status is normal.

[0074] If the peak value of vibration frequency or peak value of vibration amplitude obtained in a single acquisition exceeds the initial reference value by 50%, it is determined that there is a sudden fault such as broken tooth or foreign object intrusion. The machine should be stopped immediately, and cross-verification should be completed by observation with an industrial endoscope, measurement of radial runout of the shaft with a dial indicator, or disassembly inspection.

[0075] This invention addresses the shortcomings of existing compressor shaft wear detection methods, which generally require shutdown and disassembly, are complex to operate and rely on professional personnel, and suffer from uncontrolled operating conditions leading to disordered and incomparable data. Based on the classic vibration principle that "shaft wear is positively correlated with vibration characteristic parameters," this invention constructs a standardized closed-loop detection system that can be operated by ordinary testing personnel without disassembly. This invention sets up a two-level fault judgment logic. The first level determines the rate of gradual wear deterioration of the shaft through long-term linear fitting of the slope. The second level identifies sudden faults such as foreign objects and broken teeth through single-data acquisition peak mutations. The accelerometer can be an industrial-grade piezoelectric accelerometer (such as PCB 356A16, ICP 603C01), and the displacement sensor can be a non-contact eddy current displacement sensor (such as B&K 4507, Schenker IN-081). Both have wideband response, high signal-to-noise ratio characteristics, strong anti-interference capabilities in industrial environments, and can accurately capture minute vibration changes in the shaft.

[0076] This invention employs a zoned arrangement of two types of sensors: an accelerometer is mounted flush against the rear bearing of the compressor to directly capture the shaft vibration transmitted by the bearing; a displacement sensor is mounted on the compressor's mounting bracket to collect radial displacement changes of the shaft in a non-contact manner. This separate arrangement of the two types of sensors allows for the simultaneous acquisition of two independent characteristic signals: bearing vibration excitation and shaft radial displacement. The data corroborate each other, improving the accuracy of wear identification. The rear bearing location represents the shortest path for shaft vibration to travel to the housing, resulting in minimal signal attenuation and freedom from interference from other components, thus providing the most accurate reflection of the fit between the shaft and bearing. By permanently marking the installation positions of the accelerometer and displacement sensor, the installation angle, clamping force, and installation distance of the sensors are ensured to be completely consistent for each test, eliminating the influence of installation errors on the data and guaranteeing a unique and comparable benchmark for data collected at different times.

[0077] To address the core issue of data disorder in existing technologies, this invention completely locks down all environmental and operational variables by strictly solidifying and unifying standardized operating conditions: the initial temperature of the environmental chamber is set to -30℃, and the main compressor is controlled to operate at 50% of its rated power. The compressor's operating power can be read in real time via the device's built-in display panel or a host computer equipped with INCA software. The auxiliary compressor is shut down, and the entire machine runs continuously for 30 minutes. The purpose of this step is to ensure that the lubricating oil inside the compressor reaches a stable operating temperature and viscosity, eliminating the influence of lubricating oil viscosity changes and component thermal expansion and contraction on vibration during the cold start phase. Data acquisition begins when the actual temperature inside the environmental chamber stabilizes at 30℃ and the compressor's outlet pressure stabilizes at 30MPa. At this point, the compressor is in a state of complete thermal equilibrium, and the vibration signal is determined only by the wear state of the shaft. The acquisition time is set to 5-10 minutes, ensuring that enough vibration cycles are collected for statistical averaging while avoiding operating condition drift caused by prolonged acquisition. Data acquisition relies on the ETASES650 device to establish a communication link between the sensor and the host computer equipped with INCA software, enabling real-time recording and storage of vibration and displacement signals.

[0078] To address high-frequency random noise in industrial environments, such as electromagnetic vibration of motors, equipment resonance, and airflow disturbance, this invention employs a 10-point moving average filter to preprocess the original signal. This method effectively suppresses high-frequency noise while preserving low-frequency shaft vibration characteristics. Combined with a 1kHz sampling frequency, it can fully cover the main vibration frequency range of 10~500Hz for industrial compressor shafts, avoiding signal distortion. Specifically, the 10-point moving average filter involves calculating the arithmetic mean of the signal values ​​at the current sampling point and the previous nine consecutive sampling points, using this average as the filtered output signal for the current moment. After preprocessing, acceleration and displacement amplitude data are generated into time-series curves. The vibration frequency is calculated using the alternating frequency of positive and negative values ​​per unit time in the acceleration curve, and the vibration amplitude is calculated using the peak value of the displacement amplitude curve, transforming the abstract electrical signal into quantifiable physical characteristic parameters.

[0079] Considering that shaft wear is a gradual process, and single-test data can only reflect the current state and cannot determine the rate of deterioration, this invention innovatively uses the daily trend slope for quantitative judgment: A linear function is fitted with the test date as the x-axis and the corresponding vibration parameter as the y-axis; the resulting slope is the daily average rate of change of the vibration parameter, which can objectively reflect the evolution speed of wear. Based on a large amount of long-term operational test data from environmental chamber compressors, this invention sets 0.01 as the safety judgment threshold. If the daily slope of vibration amplitude is greater than 0.01 mm / day and / or the daily slope of vibration frequency is greater than 0.01 Hz / day, either parameter exceeding the standard indicates that shaft wear is rapidly intensifying, and the clearance has exceeded the design safety range. Failure to repair in time may lead to serious malfunctions such as compressor seizure or even breakage. When both slopes are less than or equal to the corresponding thresholds, it indicates that the shaft is in a normal wear stage and the operating state is stable. The baseline data is the initial data obtained after the compressor has undergone shaft / bearing replacement or complete machine maintenance including the shaft system, following the S1 to S5 testing procedures, and collected and preprocessed according to the unified standard operating conditions in S301. Under this reference condition, the clearance between the shaft and the bearing is within the optimal design range, and the vibration characteristic value is the lowest reference value after the equipment has undergone a complete overhaul. All subsequent test data are compared and analyzed with this reference data.

[0080] In addition to judging the progressive wear trend, this invention also has the ability to warn of sudden failures: the vibration increase caused by normal wear is slow, and the vibration change of a single detection will not exceed 20% of the reference value. Therefore, this invention sets 50% of the initial reference value as the threshold for judging sudden failures. If the peak value of vibration frequency or peak value of vibration amplitude obtained in a single acquisition exceeds 50% of the initial reference value, it is judged as a non-progressive sudden failure caused by broken teeth or foreign objects intruding into the interior. The machine is stopped immediately, and cross-verification is completed by observation with an industrial endoscope, measurement of radial runout of the shaft with a dial indicator, or disassembly inspection to accurately locate the root cause of the failure and avoid safety accidents caused by high-temperature lubricating oil splashing.

[0081] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of the equivalent features of the claims be included within the present invention.

Claims

1. A method for detecting compressor shaft wear based on acceleration and displacement sensors, characterized in that, Includes the following steps: S1: Sensor positioning and installation; S2: Signal acquisition link setup; S3: Data acquisition under standard operating conditions; S4: Data preprocessing; S5: Wear trend analysis and judgment.

2. The compressor shaft wear detection method based on acceleration and displacement sensors according to claim 1, characterized in that, S1 includes: S101: The acceleration sensor is attached and fixed to the rear bearing of the compressor, and the displacement sensor is installed separately on the compressor mounting bracket. The two types of sensors are arranged in corresponding zones. S102: Set permanent marks at the respective installation points of the accelerometer and displacement sensor to ensure that both types of sensors are installed at the corresponding marked positions during each test.

3. The compressor shaft wear detection method based on acceleration and displacement sensors according to claim 1, characterized in that, S2 includes: S201: Establish a communication connection between the accelerometer, displacement sensor and host computer through the ETAS ES650 data acquisition device; S202: Use a host computer equipped with INCA software to read and record the vibration and displacement signals output by the sensor in real time.

4. The compressor shaft wear detection method based on acceleration and displacement sensors according to claim 1, characterized in that, S3 includes: S301: Manually control the environmental chamber compressor to operate under preset uniform standard conditions; S302: After the operating conditions stabilize, start the host computer to begin data acquisition. After the acquisition is completed, save the original data under the corresponding operating conditions.

5. The compressor shaft wear detection method based on acceleration and displacement sensors according to claim 4, characterized in that, The specific pre-set unified standard operating condition in S301 is as follows: the initial temperature of the environmental chamber is set to -30℃, the main compressor is controlled to run at 50% of the rated power, the auxiliary compressor is kept off, and the operation is continued for 30 minutes until the actual temperature in the environmental chamber is stable at 30℃ and the compressor outlet pressure is stable at 30MPa before data collection is carried out; the data collection time in S302 is 5~10 minutes, and the operating condition is kept stable during the collection process.

6. The compressor shaft wear detection method based on acceleration and displacement sensors according to claim 1, characterized in that, S4 includes: S401: Performs moving average filtering on the acquired raw acceleration and displacement signals to eliminate noise data caused by environmental interference; S402: Extract the average values ​​of vibration frequency and vibration amplitude based on the filtered signal; S403: Generate time-series curves from the preprocessed acceleration data and displacement amplitude data, where the frequency of positive and negative alternations per unit time of the acceleration curve corresponds to the actual vibration frequency of the compressor, and the peak value of the displacement amplitude curve corresponds to the vibration amplitude of the compressor.

7. The compressor shaft wear detection method based on acceleration and displacement sensors according to claim 6, characterized in that, In S401, the moving average filter is a 10-point moving average filter, and the sensor sampling frequency is set to 1kHz.

8. The compressor shaft wear detection method based on acceleration and displacement sensors according to claim 1, characterized in that, S5 includes: S501: Under the same standard operating conditions as the first test, repeat S1-S4 regularly every day, and confirm that the sensor installation position is completely aligned with the permanent mark before each test; S502: Compare the preprocessed data from each round with the baseline data; S503: Using the detection date as the horizontal axis and the corresponding data as the vertical axis, a linear function is used for linear fitting to obtain the slope of the daily variation trend of vibration amplitude and vibration frequency. S504: Determine the operating status of the compressor's internal shaft based on the slope obtained from the fitting.

9. The compressor shaft wear detection method based on acceleration and displacement sensors according to claim 8, characterized in that, In S502, the reference data is the initial data obtained by executing S1 to S5 and collecting and preprocessing according to the unified standard operating conditions in S301 after the compressor has completed shaft / bearing replacement or whole machine maintenance including shaft system. In S504, the judgment rule is as follows: if the daily change slope of vibration amplitude is greater than 0.01 mm / day and / or the daily change slope of vibration frequency is greater than 0.01 Hz / day, if either parameter is satisfied, it is determined that the shaft is in rapid wear and needs to be repaired in time; if both slopes are less than or equal to the corresponding threshold, it is determined that the operating status is normal.

10. The compressor shaft wear detection method based on acceleration and displacement sensors according to claim 9, characterized in that, If the peak value of vibration frequency or peak value of vibration amplitude obtained in a single acquisition exceeds the initial reference value by 50%, it is determined that there is a sudden fault such as broken tooth or foreign object intrusion. The machine should be stopped immediately, and cross-verification should be completed by observation with an industrial endoscope, measurement of radial runout of the shaft with a dial indicator, or disassembly inspection.