A method for ultrasonic decoupling measurement of lubricating film thickness and wear of a wind power sliding bearing
By employing ultrasonic measurement methods and decoupling technology between lubrication film thickness and wear, the problem of lubrication-wear detection for wind turbine sliding bearings under extreme operating conditions has been solved, enabling precise design and online monitoring, and improving the service life and design accuracy of wind turbine sliding bearings.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUNAN UNIV
- Filing Date
- 2023-05-26
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies are insufficient to accurately detect the lubrication-wear mechanism of wind turbine sliding bearings under extreme operating conditions, which affects their precision design and service life.
An ultrasonic measurement method is adopted, which utilizes the ultrasonic decoupling technique between lubricating film thickness and wear amount. By combining the characteristics of reflected signals and time-of-flight differences with Hilbert transform and windowed sinc function interpolation, the synchronous measurement of lubricating film thickness and wear amount can be achieved.
It enables accurate measurement of the lubrication film thickness and wear of wind turbine sliding bearings, supports online observation of the lubrication-wear evolution under different service conditions, and improves the accuracy and reliability of the design.
Smart Images
Figure CN116625283B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of monitoring and diagnostic technology, and in particular to a method for monitoring and diagnosing sliding bearings. Background Technology
[0002] Due to their small radial dimensions, good tolerance to material defects and external impurities, and replaceability on the tower, sliding bearings have become the development trend for large wind turbine bearings, replacing rolling bearings. However, wind turbine sliding bearings operate at low speeds (0-20 rpm), bear large loads (average specific pressure typically greater than 10 MPa), experience frequent starts and stops, and are subjected to complex bending moments. Mixed lubrication between the bearing bush and journal easily leads to localized and global wear. To ensure a service life of at least 20 years for wind turbine sliding bearings, similar to the main turbine, it is necessary to fully consider the localized load-sharing and lubrication characteristics of wind turbine sliding bearings and conduct precise wear-reduction design. However, limited by testing technology, current research mainly relies on theoretical model predictions. The accuracy of these models needs further verification and improvement, and the lubrication-wear mechanism of wind turbine sliding bearings under extreme operating conditions cannot yet be accurately revealed. This has become a bottleneck restricting the further precision design of wind turbine sliding bearings. Therefore, there is an urgent need for an ultrasonic synchronous detection method for the lubrication film thickness and wear of wind turbine sliding bearings, to observe the lubrication-wear evolution law of wind turbine sliding bearings under different service conditions online, to verify and revise the lubrication-wear evolution theory of wind turbine sliding bearings, and to improve the accuracy and reliability of the precise wear reduction design of wind turbine sliding bearings. Summary of the Invention
[0003] To address the aforementioned problems in the existing technology, this invention provides an ultrasonic decoupling measurement method for the thickness and wear of the lubricating film in a wind turbine sliding bearing, which can simultaneously obtain the thickness and wear of the lubricating film in the wind turbine sliding bearing.
[0004] In this invention, the thickness of the lubricating film and the amount of wear of the wind turbine sliding bearing are obtained by utilizing the reflection signal characteristics of ultrasonic waves at different interfaces. The thickness of the lubricating film is obtained by utilizing the reflection signal characteristics of ultrasonic waves at the lubrication interface, while the amount of wear is obtained by utilizing the change in the time difference of the reflection signal of ultrasonic waves at the upper and lower interfaces of the alloy layer.
[0005] This invention utilizes the characteristics of ultrasonic wave reflection signals at the lubrication interface to measure the thickness of the lubrication film in wind turbine sliding bearings. Based on the measurement range, the time-of-flight method, resonance method, and spring model method are employed to determine the lubrication film thickness of the wind turbine sliding bearing according to the functional relationship between the lubrication film thickness and the amplitude and phase of the reflected signal.
[0006] This invention measures the wear of wind turbine sliding bearings by measuring the change in flight time of ultrasonic reflected signals at the interfaces between the upper and lower alloy layers. The flight time of the reflected signal is determined by the wave velocity of the ultrasonic wave and the thickness of the alloy layer. Wear reduces the thickness of the alloy layer, thus reducing the path length of the ultrasonic wave transmission. Therefore, the flight time of the ultrasonic wave decreases with the wear of the wind turbine sliding bearing. Furthermore, the Hilbert transformation is used to remove the influence of the phase shift at the lubrication layer interface on the characteristics of the ultrasonic reflected signal for measuring wear. The surface wear is then obtained by combining the change in flight time of the ultrasonic reflected signal at the interfaces between the upper and lower alloy layers with the propagation speed of the ultrasonic wave within the alloy layer.
[0007] This invention utilizes the Hilbert transform to remove the influence of the phase shift at the lubrication layer interface on the ultrasonic reflection signal characteristics of wear, thereby obtaining the ultrasonic characterization signal of wear. Since the upper interface of the alloy layer in wind turbine sliding bearings is typically also the lubrication interface, obtaining surface wear by measuring the change in flight time of the reflected signals from the upper and lower interfaces of the alloy layer is affected by the phase shift caused by the thickness and state of the lubrication film at the lubrication interface. However, the time shift between the envelopes obtained by the Hilbert transform of the reflected signals from the upper and lower interfaces of the alloy layer is solely due to the coating thickness change caused by wear. Therefore, the wear of wind turbine sliding bearings can be measured using the Hilbert transform for decoupling.
[0008] In this invention, the reflected signal is interpolated using a windowed sinc function to improve the resolution of wear measurement. The resolution of wear measurement depends on the sound velocity in the alloy layer of the wind turbine sliding bearing and the sampling interval. Typically, the resolution of wear measurement is in the tens of micrometers, but in the early stages of wear, the wear amount is very small, making it undetectable. By using a windowed sinc function to interpolate the reflected signal, M-1 points are equally interpolated between two sampling points, thus improving the resolution of wear thickness measurement by 1 / M, allowing wear in the early stages to be detected.
[0009] In summary, this invention utilizes the change in time-of-flight of the ultrasonic reflection signal at the interface between the upper and lower alloy layers to obtain the wear amount. The phase shift caused by the thickness and state of the lubricating film at the lubrication interface affects the time-of-flight of the reflected signal. The Hilbert transform effectively removes the influence of the lubrication interface phase shift on the ultrasonic reflection signal characteristics of the wear amount, obtaining the ultrasonic characterization signal of the wind turbine sliding bearing wear amount. Furthermore, interpolation of the reflected signal using a windowed sinc function improves the wear measurement resolution. Depending on the measurement range, the time-of-flight method, resonance method, and spring model method are employed to obtain the lubricating film thickness of the wind turbine sliding bearing based on the functional relationship between the lubricating film thickness and the amplitude and phase of the reflected signal. Therefore, this invention achieves decoupled ultrasonic measurement of the lubricating film thickness and wear amount of wind turbine sliding bearings, simultaneously obtaining both the lubricating film thickness and the wear amount.
[0010] The technical solution adopted by this invention to solve its technical problem includes the following steps:
[0011] (1) The thickness of the lubricating film of the wind turbine sliding bearing was determined by measuring the reflected signal characteristics of the ultrasonic wave at the lubrication interface. Based on the measurement range, the time-of-flight method, resonance method, and spring model method were used respectively to obtain the lubricating film thickness value of the wind turbine sliding bearing according to the functional relationship between the lubricating film thickness value and the amplitude and phase of the reflected signal.
[0012] (2) The wear amount is obtained by using the change in flight time of the ultrasonic wave reflected signal at the upper and lower interfaces of the alloy layer. The reflected signal at the upper interface of the alloy layer is interpolated by the windowed sinc function, and the envelope of the interpolated reflected signal is obtained by Hilbert transformation. The time interval between the envelope and the reflected signal at the lower interface of the alloy layer is obtained to obtain the wear amount.
[0013] (3) The thickness and wear of the lubricating film of the wind turbine sliding bearing were measured at the same time. Attached Figure Description
[0014] Figure 1 This is a flowchart of the ultrasonic decoupling measurement method for the thickness of the lubricating film and the amount of wear in wind turbine sliding bearings;
[0015] Figure 2 It is a scaled-down test bench for simulating the working conditions of wind turbine sliding bearings equipped with ultrasonic sensors;
[0016] Figure 3 These are ultrasonic wave reflection signals from various interfaces; Detailed Implementation
[0017] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention. The embodiments of the present invention include the following parts:
[0018] Figure 1 This is a flowchart of an ultrasonic decoupling measurement method for the thickness of the lubricating film and the amount of wear in wind turbine sliding bearings.
[0019] Figure 2 This is a scaled-down simulation test bench for wind turbine sliding bearings equipped with ultrasonic sensors. Ultrasonic testing experiments with varying wear levels were conducted using this test bench, and the test results were compared and verified with the disassembly and inspection results.
[0020] Figure 3These are the ultrasonic reflection signals at each interface. The dashed line represents the ultrasonic reflection signal when the wind turbine sliding bearing is not worn, serving as a reference signal; the solid line represents the ultrasonic reflection signal when the wind turbine sliding bearing is worn, i.e., the wear signal. The first segment of the signal represents the reflection signal from the lower surface of the alloy layer, and the second segment represents the reflection signal from the upper surface of the alloy layer (lubrication interface). The characteristic of the lubrication film thickness is the change in the amplitude of the ultrasonic reflection signal at the lubrication interface, while the wear characteristic is the change in the flight time of the ultrasonic reflection signal at the upper and lower interfaces of the alloy layer.
[0021] This embodiment uses ultrasonic decoupling to measure the thickness of the lubricating film and the amount of wear in wind turbine sliding bearings. It simultaneously obtains the thickness of the lubricating film and the amount of wear in wind turbine sliding bearings, which facilitates online observation of the lubrication-wear evolution law of wind turbine sliding bearings under different service conditions, so as to carry out precise wear reduction design of wind turbine sliding bearings.
[0022] This embodiment uses a scaled-down operating condition simulation test bench for wind turbine sliding bearings to conduct ultrasonic testing experiments with different wear levels, and compares and verifies the test results with the disassembly and inspection results.
[0023] This embodiment utilizes the reflected signal characteristics of ultrasonic waves on the upper surface (lubrication interface) of the alloy layer to measure the thickness of the lubricating film in a wind turbine sliding bearing. Based on the measurement range, the time-of-flight method, resonance method, and spring model method are employed to obtain the lubricating film thickness value of the wind turbine sliding bearing according to the functional relationship between the lubricating film thickness value and the amplitude and phase of the reflected signal.
[0024] This embodiment measures the wear of wind turbine sliding bearings by utilizing the change in flight time between the ultrasonic reflection reference signal and the wear signal. Furthermore, it employs Hilbert transformation to eliminate the influence of lubrication layer interface phase shift on the characteristics of the ultrasonic reflection signal related to wear, and combines the change in flight time between the ultrasonic reflection reference signal and the wear signal with the propagation speed of ultrasound waves in the alloy layer to obtain the surface wear amount.
[0025] This example utilizes the Hilbert transform to effectively remove the influence of the lubrication interface phase shift on the ultrasonic reflection signal characteristics of wear, thereby eliminating the phase shift effect caused by the thickness and state of the lubrication film at the lubrication interface on the time of flight of the reflection signals from the upper and lower interfaces of the alloy layer, and obtaining the ultrasonic characterization signal of wear. The time shift between the envelopes obtained by the Hilbert transform of the reflection signals from the upper and lower interfaces of the alloy layer is solely due to the change in alloy layer thickness caused by wear. Therefore, the Hilbert transform is used to achieve ultrasonic decoupled measurement of the lubrication film thickness and wear amount in wind turbine sliding bearings.
[0026] This example improves wear measurement resolution by interpolating the reflected signal from the upper surface (lubrication interface) of the alloy layer using a windowed sinc function. The resolution of wear measurement depends on the sound velocity and sampling interval in the wind turbine sliding bearing alloy layer. In this embodiment, the uninterpolated reflected signal has a wear measurement resolution of 30 micrometers, making early-stage wear undetectable. By interpolating 99 points equally between two sampling points, the wear thickness measurement resolution can be improved to 0.3 micrometers, allowing wear in its early stages to be detected.
[0027] This example utilizes the reflection signal characteristics of ultrasonic waves at different interfaces to simultaneously obtain the lubrication film thickness and wear amount of a wind turbine sliding bearing. Based on the reflection signal characteristics of the wear signal on the upper surface of the alloy layer (lubrication interface), and according to its measurement range, the time-of-flight method, resonance method, and spring model method are employed respectively. The lubrication film thickness value of the wind turbine sliding bearing at different wear levels is obtained according to the functional relationship between the lubrication film thickness value and the amplitude and phase of the reflected signal. Based on the change in the time of flight of the reference signal and the wear signal on the upper and lower surfaces of the alloy layer, the influence of the phase shift at the lubrication film thickness interface on the ultrasonic reflection signal characteristics of the wear amount is removed using Hilbert transform. Furthermore, the wear amount of the wind turbine sliding bearing is decoupled and obtained by interpolation of the reflection signal on the upper surface of the alloy layer (lubrication interface) using a windowed sinc function, achieving a wear measurement resolution of less than 1 micrometer.
[0028] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A method for ultrasonic decoupling measurement of lubricating film thickness and wear amount in wind turbine sliding bearings, characterized in that: By utilizing the ultrasonic reflection signals at the upper and lower interfaces of the alloy layer after Hilbert transformation, ultrasonic decoupling measurement of the lubricating film thickness and wear of wind turbine sliding bearings is performed, thereby simultaneously obtaining the lubricating film thickness and surface wear of the wind turbine sliding bearings. Specifically, using the ultrasonic reflection signals on the lubricating layer, and based on their measurement range, the time-of-flight method, resonance method, and spring model method are employed respectively to obtain the lubricating film thickness value based on the functional relationship between the lubricating film thickness value and the amplitude and phase of the reflected signal. The Hilbert transformation is used to remove the time shift caused by the phase shift at the lubricating layer interface, and then the wear of the wind turbine sliding bearing is obtained by the change in the time of flight of the ultrasonic reflection signal envelope at the upper and lower interfaces of the alloy layer.
2. The ultrasonic decoupling measurement method for the thickness of the lubricating film and the amount of wear in wind turbine sliding bearings according to claim 1, characterized in that: The time change of the envelope of the reflected signal at the upper and lower interfaces of the alloy layer obtained by Hilbert transform is only caused by the change in the thickness of the alloy layer due to wear.
3. The ultrasonic decoupling measurement method for the thickness of the lubricating film and the amount of wear in wind turbine sliding bearings according to claim 2, characterized in that: The reflection signals at the upper and lower interfaces of the alloy layer are interpolated by applying a windowed sinc function, and then the time-of-flight change of the envelope of the reflection signals at the upper and lower interfaces of the alloy layer is obtained by Hilbert transform, so as to achieve high-precision and high-resolution wear measurement.