Embedded Ultrasonic Monitoring Method and System for Oil Film Thickness in the Contact Area of ​​Rolling Bearings

Abstract

This invention discloses an embedded ultrasonic monitoring method and system for oil film thickness in the contact area of ​​rolling bearings, belonging to the field of mechanical lubrication condition monitoring technology. The method includes: determining the core electrical parameters of the excitation pulse based on the characteristics of a piezoelectric transducer attached to the bearing surface; generating a matching excitation pulse signal through an excitation pulse transmitting circuit and exciting ultrasonic waves; receiving the echo signal reflected from the contact area, and calculating the reflection coefficient amplitude in real time using a parallel processing method combining asynchronous data streams and multi-channel pipelines in a field-programmable gate array; and automatically locating the contact area and calculating the oil film thickness in real time based on the change in the reflection coefficient amplitude using a dual-threshold algorithm. This invention solves the problems of insufficient spatial resolution due to excitation pulse mismatch and poor real-time performance due to low algorithm efficiency, achieving microsecond-level response and on-machine real-time accurate monitoring of sub-micron oil film thickness in the contact area of ​​rolling bearings.

Description

Technical Field

[0001] This invention belongs to the field of mechanical lubrication condition monitoring technology, specifically relating to an embedded ultrasonic monitoring method and system for oil film thickness in the contact area of ​​rolling bearings. Background Technology

[0002] Rolling bearings are the core load-bearing components of rotating machinery. Their low-friction and high-load performance depends entirely on a submicron-sized dynamic lubricating oil film formed between the rolling elements and the raceways. Therefore, the thickness of this dynamic oil film is the most direct parameter for assessing the bearing's elastohydrodynamic lubrication state and providing early warning of failure. Due to the structural precision of rolling bearings and the highly dynamic nature of their operating environment, this submicron-sized oil film is difficult to measure. The main challenges are: 1) The bearing, bearing housing, and shaft are all interference fits, and any measurement method that damages the bearing structure will alter the bearing prestress; 2) The oil film is extremely thin, and any invasive measurement will change the morphology of the oil film, thus altering the actual oil film thickness; 3) The main load-bearing oil film exists in the elastic deformation contact area between the rolling elements and the raceways. Under operating conditions, measuring this micron-scale contact area requires very high resolution and real-time performance. Due to these factors, existing measurement methods cannot meet the practical application requirements for monitoring the oil film thickness in the contact area of ​​rolling bearings. Ultrasonic methods, due to their non-invasive measurement and strong penetration, meet the first two requirements, but still cannot meet the requirements for high resolution and high real-time performance.

[0003] In the same field, an existing invention patent (CN118031863A) discloses an ultrasonic measurement method for the center oil film thickness of the elastohydrodynamic contact zone of a high-speed rolling bearing. This method uses a light-absorbing area on the cage as a trigger reference, combined with a delay design, to focus and scan the ultrasonic pulse at the center of the contact zone, thereby measuring the center oil film thickness under high-speed conditions. However, this method relies on an external optical triggering system and a water-focusing ultrasonic probe, resulting in a complex system structure that is not easily integrated or embedded. Data processing depends on post-processing, failing to achieve embedded real-time processing, making it difficult to meet the real-time requirements of online monitoring of high-speed bearings. Furthermore, it does not address the electrical matching design between the excitation pulse and the piezoelectric transducer, directly using a common sharp pulse signal, making it difficult to guarantee high-resolution measurement conditions from the signal source.

[0004] The shortcomings of the aforementioned technologies collectively lead to two major technological bottlenecks in online real-time monitoring of rolling bearing oil film thickness:

[0005] 1) Insufficient spatial resolution. Existing ultrasonic excitation circuits have low pulse repetition frequency, narrow bandwidth, and insufficient energy, resulting in the inability to accurately focus the sound field on the tiny contact area. The root cause is that the working mechanism of the excitation pulse emission circuit is disconnected from that of the piezoelectric transducer, and the bandwidth, energy, and velocity of the excitation pulse cannot simultaneously meet the requirements of high-resolution detection.

[0006] 2) Poor real-time computing performance. There is a lack of algorithms that can automatically and in real-time locate the contact area in embedded systems, and the response speed of the computer-based film thickness calculation scheme is slow, which cannot meet the microsecond-level response requirements of bearings.

[0007] Therefore, it is necessary to break through the above-mentioned bottlenecks at the root to meet the urgent need for accurate, real-time, and on-machine monitoring of the lubrication status of rolling bearings in engineering sites. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide an embedded ultrasonic monitoring method and system for oil film thickness in the contact area of ​​rolling bearings, which addresses the shortcomings of the prior art. This method and system solves the problems of insufficient spatial resolution in the contact area caused by mismatched piezoelectric transducers due to excitation pulses, and poor real-time performance of film thickness calculation due to low algorithm efficiency. The invention achieves on-machine real-time accurate monitoring of oil film thickness in rolling bearings with submicron resolution and microsecond response.

[0009] The present invention adopts the following technical solution:

[0010] The oil film thickness in the contact area of ​​a rolling bearing is monitored using an embedded ultrasonic method, including the following steps:

[0011] S1. A non-destructive testing method is adopted, in which a textured piezoelectric transducer patch is solidified on the surface of a rolling bearing. The core electrical parameters required for the excitation pulse are determined based on the resonant frequency of the textured piezoelectric transducer patch and the emitted sound pressure.

[0012] S2. Based on the core electrical parameters required for the excitation pulse obtained in S1, an excitation pulse signal matching the textured piezoelectric transducer is generated through the excitation pulse transmitting circuit.

[0013] S3. The excitation pulse signal generated in S2 is input to the textured piezoelectric transducer patch to generate ultrasonic waves. The ultrasonic echo signal reflected by the rolling bearing contact area is received, and the ultrasonic echo signal is processed in parallel in the field programmable gate array (FPGA) using an asynchronous data stream-multiplexing pipeline approach to obtain the amplitude of the reflection coefficient of the rolling bearing contact area.

[0014] S4. Based on the reflection coefficient amplitude of the rolling bearing contact area obtained in S3, the contact area of ​​the rolling bearing is automatically located in real time using a dual threshold algorithm, and the oil film thickness of the contact area is calculated according to the reflection coefficient amplitude corresponding to the located contact area.

[0015] Preferably, in S1, the core electrical parameters required for the excitation pulse are determined, and the specific process includes:

[0016] S101. Based on the admittance model of the piezoelectric transducer, determine the resonant frequency of its thickness stretching vibration mode, and determine the effective bandwidth range of the excitation pulse spectrum according to the resonant frequency to obtain the effective range of the excitation pulse width.

[0017] S102. Based on the effective range of the excitation pulse width determined in S101, the amplitude of the excitation pulse is determined by the expression of the sound pressure emitted by the piezoelectric transducer under the action of the excitation pulse, combined with the amplitude ratio between the excitation electrical pulse and the echo electrical signal.

[0018] S103. Determine the repetition frequency of the excitation pulse based on the roller linear velocity. Combined with the excitation pulse amplitude obtained in S102 and the bearing operating parameters, determine the capacitor discharge time constant in the excitation pulse transmitting circuit. τ 0, so that the contact area of ​​each roller can reflect a number of effective ultrasonic echo signals.

[0019] Preferably, in S102, the sound pressure emitted by the piezoelectric transducer The expression is:

[0020]

[0021] in, It is the wavelength of the ultrasonic pressure in the medium; l It is the length of the piezoelectric transducer; l w It is the width of the piezoelectric transducer; K It is the wavenumber of the ultrasound. yes xoz Scattering angle on a plane; yes yoz Scattering angle on a plane; P 0 represents the sound pressure amplitude obtained from the initial excitation; r It is the distance between the diffusion location and the origin; s It is the sound pressure emitted by the piezoelectric transducer and the initial sound pressure. The amplitude ratio.

[0022] Preferably, in S103, the capacitor discharge time constant in the excitation pulse emission circuit is... τ 0 is:

[0023]

[0024] in, W It is the applied load. R ' It is the equivalent radius of curvature. m It is the number of valid ultrasonic echo signals collected when the roller passes through the piezoelectric transducer. v r It is the linear velocity of the roller. LIt is the axial length of the roller. E ' It is the equivalent elastic modulus of the bearing contact pair.

[0025] Preferably, in S2, the excitation pulse transmitting circuit is a negative high-voltage spike pulse transmitting circuit, whose output excitation pulse in the time domain... v ( t )for:

[0026]

[0027] Pulse width of the output excitation pulse W ( t 0 , )for:

[0028]

[0029] Spectrum of the output excitation pulse V ( ω )for:

[0030]

[0031] in, τ 0 represents the capacitor discharge time constant. V 0 represents the absolute value of the pulse's time-domain peak value. k This is the absolute value of the slope of the falling edge of the pulse; t 0 represents the fall time of the excitation pulse; t It is a time variable; j It is the imaginary unit; ω It is the angular frequency of the excitation pulse; e It is a natural constant.

[0032] Preferably, in S3, the parallel processing using a combination of asynchronous data streams and multi-pipelines specifically includes:

[0033] The process of calculating the reflection coefficient amplitude is divided into a time-domain signal truncation stage, a fast Fourier transform stage, and a reflection coefficient calculation stage.

[0034] For the time-domain signal truncation stage and the fast Fourier transform stage, a parallel processing logic combining asynchronous data streams and multiple pipelines is adopted. The parallel processing logic includes clock domain isolation through an asynchronous first-in-first-out queue (FIFO), acceleration of operation by using a higher operating frequency, and configuration of at least two parallel operation pipelines to achieve immediate takeover of the operation task.

[0035] The reflection coefficient calculation stage is processed using an asynchronous data flow architecture.

[0036] Preferably, in S3, the reflection coefficient amplitude |R ( f )| is:

[0037]

[0038] in, S ( f The signal spectrum is the echo signal when the oil film is present. A ( f () represents the spectrum of the reflected signal at the raceway-air interface. V ref The reflection coefficient is the raceway-air interface coefficient.

[0039] Preferably, in S4, the real-time automatic positioning of the contact area of ​​the rolling bearing using a dual-threshold algorithm specifically includes:

[0040] Monitor the amplitude change of the reflection coefficient at the center frequency of the piezoelectric transducer;

[0041] The amplitude of the reflection coefficient is limited, and values ​​with an amplitude greater than 1 are set to 1;

[0042] Traverse the processed data, and mark the start time when the amplitude changes from 1 to less than 1, and mark the end time when the amplitude changes from less than 1 to 1.

[0043] The location of the contact area is determined based on the start and end times.

[0044] Preferably, determining the location of the contact area specifically includes:

[0045] Calculate the time difference between the end time and the start time, and make a preliminary judgment when the time difference is greater than a preset time threshold;

[0046] The reflection coefficient amplitude corresponding to the midpoint between the start and end times is obtained. When the reflection coefficient amplitude is less than a preset amplitude threshold, a final determination is made and the location of the contact area is confirmed.

[0047] Secondly, embodiments of the present invention provide an embedded ultrasonic monitoring system for oil film thickness in the contact area of ​​a rolling bearing, comprising:

[0048] The parameter module employs a non-destructive testing method that involves solidifying textured piezoelectric transducer patches onto the surface of a rolling bearing. The core electrical parameters required for the excitation pulse are determined based on the resonant frequency of the textured piezoelectric transducer patch and the emitted sound pressure.

[0049] The pulse module generates an excitation pulse signal that matches the textured piezoelectric transducer patch through the excitation pulse transmitting circuit, based on the core electrical parameters required for the excitation pulse obtained from the parameter module.

[0050] The signal module inputs the excitation pulse signal generated by the pulse module to the textured piezoelectric transducer patch to generate ultrasonic waves, receives the ultrasonic echo signal reflected by the rolling bearing contact area, and processes the ultrasonic echo signal in parallel in the field programmable gate array (FPGA) using an asynchronous data stream-multiplexing approach to obtain the amplitude of the reflection coefficient of the rolling bearing contact area.

[0051] The calculation module uses a dual-threshold algorithm to automatically locate the contact area of ​​the rolling bearing in real time based on the reflection coefficient amplitude of the rolling bearing contact area obtained from the signal module, and calculates the oil film thickness of the contact area according to the reflection coefficient amplitude corresponding to the located contact area.

[0052] Thirdly, a computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the steps of the above-described method for monitoring the oil film thickness in the contact area of ​​a rolling bearing using embedded ultrasonic monitoring.

[0053] Fourthly, embodiments of the present invention provide a computer-readable storage medium including a computer program, which, when executed by a processor, implements the steps of the above-described method for embedded ultrasonic monitoring of oil film thickness in the contact area of ​​a rolling bearing.

[0054] Fifthly, a chip includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the steps of the above-described method for monitoring the oil film thickness in the contact area of ​​a rolling bearing using embedded ultrasonic monitoring.

[0055] In a sixth aspect, embodiments of the present invention provide an electronic device including a computer program, which, when executed by the electronic device, implements the steps of the above-described method for embedded ultrasonic monitoring of oil film thickness in the contact area of ​​a rolling bearing.

[0056] Compared with the prior art, the present invention has at least the following beneficial effects:

[0057] An embedded ultrasonic monitoring method for oil film thickness in the contact area of ​​rolling bearings overcomes the problem of excitation source and sensor decoupling in traditional methods by inversely deriving excitation parameters based on transducer characteristics and then generating matching signals, laying the foundation for high-resolution detection. The introduced FPGA parallel processing architecture, specifically designed for the microsecond-level acoustic window of high-speed bearings, ensures real-time data processing. A dual-threshold positioning algorithm enables automatic, real-time identification of the contact area, eliminating reliance on manual intervention or complex external triggering devices. This method addresses the two core challenges of resolution and real-time performance, organically integrating piezoelectric transducer adaptation design, FPGA parallel processing, and the dual-threshold positioning algorithm. It fundamentally solves the problems of insufficient spatial resolution caused by excitation pulse and transducer mismatch, and poor real-time performance of traditional host computer processing. The process is logically coherent, with each step progressively, achieving the integrated requirements of non-destructive deployment, high-resolution detection, and real-time computation, adapting to the precision structure and highly dynamic operating environment of rolling bearings.

[0058] Furthermore, based on the physical model of the textured piezoelectric transducer patch, its intrinsic resonant frequency is determined, and the required effective bandwidth of the excitation pulse is derived. This is crucial for ensuring that the excitation energy can efficiently excite the transducer and generate narrow-pulse ultrasonic waves, directly determining the axial resolution of the measurement. Based on the determined bandwidth range, the required pulse amplitude is calculated by combining the sound pressure propagation model and the echo signal-to-noise ratio requirements, ensuring that the emitted ultrasonic waves have sufficient energy to penetrate the bearing material and generate a recognizable echo signal. Starting from the time-domain dynamic characteristics, the pulse repetition frequency and capacitor discharge time constant are determined according to the roller linear velocity and contact area size to ensure that each passing roller contact area can be detected by a sufficient number of effective pulses. The coordinated design from the frequency domain, energy domain, and time domain dimensions ensures that the generated excitation pulse perfectly matches the physical characteristics of the transducer and the object under test.

[0059] Furthermore, the sound pressure expression and the meaning of each parameter quantify the relationship between the excitation pulse amplitude and the ultrasonic signal propagation attenuation. This expression clearly describes the influence of piezoelectric transducer size, propagation distance, and scattering angle on sound pressure. Combined with the amplitude ratio of the excitation pulse and the echo signal, the minimum excitation energy to meet the detection requirements can be derived in reverse, avoiding signal distortion due to excessive amplitude or weak echo due to insufficient amplitude. Compared with traditional empirical amplitude settings, this ensures that the ultrasonic signal remains detectable after propagation in the bearing component, improving the accuracy of oil film thickness measurement.

[0060] Furthermore, by correlating the time constant with the bearing operating parameters, dynamic matching between the excitation pulse repetition frequency and the roller motion state is achieved. This ensures that each roller contact area can reflect a sufficient number of effective ultrasonic echo signals within the microsecond-level window of acoustic field exposure, avoiding signal superposition due to excessively high repetition frequency or missed detection due to excessively low repetition frequency. It adapts to the high-speed operation characteristics of rolling bearings, solving the problem that traditional fixed repetition frequency pulses cannot adapt to different operating conditions, and providing a time dimension guarantee for accurate detection of the contact area.

[0061] Furthermore, a negative high-voltage spike pulse transmitting circuit is adopted, which is highly compatible with the requirements of piezoelectric transducers. The negative high-voltage spike pulse has the characteristics of wide bandwidth and steep rise time, which can excite the transducer to generate high-energy, narrow-pulse ultrasonic signals, improving the focusing accuracy of the sound field. The time domain and pulse width expressions quantify key parameters such as capacitor discharge time constant and fall time, ensuring that the pulse signal is consistent with the core parameters. The spectrum expression verifies the signal bandwidth matching from the frequency dimension. Compared with traditional general-purpose transmitting circuits, this design achieves customized adaptation from circuit structure to parameter output, providing a signal source guarantee for high-resolution detection.

[0062] Furthermore, a phased parallel processing architecture is adopted to break through the speed limitations of traditional serial processing and achieve microsecond-level signal processing response. The process is divided into three stages: time-domain truncation, fast Fourier transform, and reflection coefficient calculation. For the first two stages with high real-time requirements, asynchronous FIFO clock isolation and multi-path pipeline design are used to take over the calculation tasks in parallel, improving processing efficiency. For the reflection coefficient calculation stage with lower real-time requirements, an asynchronous data flow architecture is used to ensure data buffering and stable transmission. By fully leveraging the parallel advantages of FPGA hardware, the contradiction between the large data volume of ultrasonic echo signals and the microsecond-level response requirements of bearings is resolved, providing computational support for real-time positioning of the contact area and calculation of film thickness.

[0063] Furthermore, by using the ratio of the echo spectrum when the oil film is present to the reflection spectrum at the raceway-air interface, combined with interface reflection coefficient correction, the influence of the oil film on the ultrasonic signal reflection is accurately quantified. This formula establishes a direct correlation between ultrasonic signal characteristics and the presence of the oil film, avoiding interference factors such as environmental noise and transducer characteristics, and providing accurate intermediate parameters for oil film thickness calculation. Compared with traditional methods that directly estimate based on signal amplitude, this method can effectively distinguish the reflection signals of the oil film from those of other structures, improving the accuracy and reliability of oil film thickness measurement.

[0064] Furthermore, the dual-threshold positioning algorithm enables real-time, automatic, and accurate identification of the contact area. By standardizing the data range through amplitude limiting and marking the start and end times with amplitude jumps, it eliminates the need for external triggering devices, thus adapting to embedded real-time processing requirements. Relying solely on the amplitude variation characteristics of the reflection coefficient, it avoids the drawbacks of traditional optical triggering systems, such as complex structures and difficulty in embedded deployment. It can quickly capture the contact area position during high-speed bearing operation, providing accurate regional positioning for subsequent film thickness calculations and ensuring that the measurement results focus on the actual oil film area being carried.

[0065] Furthermore, the reliability of contact area positioning is improved through dual verification using both time difference threshold and amplitude threshold. The time difference threshold eliminates false jump signals caused by noise, ensuring that the positioning area conforms to the time scale characteristics of the contact area. The amplitude threshold verifies whether the amplitude of the reflection coefficient of the positioning area conforms to the signal characteristics of the oil film, avoiding misjudging interference signals from non-contact areas as contact areas. The dual verification mechanism complements each other, effectively reducing positioning errors under high dynamic conditions, solving the problem of susceptibility to interference with single threshold determination, ensuring the accuracy and robustness of contact area positioning, and providing a reliable regional basis for accurate calculation of oil film thickness.

[0066] It is understood that the beneficial effects of the second to sixth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0067] In summary, the method of this invention systematically overcomes the technical challenges of high resolution and high real-time performance in online monitoring of oil film thickness in the contact area of ​​rolling bearings through the synergistic innovation of excitation pulse source matching design, FPGA microsecond-level parallel processing architecture, and intelligent dual-threshold positioning algorithm, achieving embedded real-time accurate monitoring with sub-micron precision and microsecond-level response.

[0068] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0069] Figure 1 This is a schematic diagram of the embedded ultrasonic monitoring method for oil film thickness in the contact area of ​​a rolling bearing according to the present invention.

[0070] Figure 2 This is a schematic diagram of the excitation pulse transmitting circuit of the present invention;

[0071] Figure 3 The excitation pulse signal emitted by the excitation pulse transmitting circuit is shown in (a) as the excitation pulse signal emitted within a certain period of time; and (b) as an enlarged view.

[0072] Figure 4This is a schematic diagram of the parallel processing logic flow combining asynchronous data stream and multi-path pipeline of the present invention, wherein (a) is a diagram of dividing the film thickness calculation process into multiple calculation stages; and (b) is a schematic diagram of the parallel operation pipeline.

[0073] Figure 5 This is a flowchart of the method for automatically positioning the contact area of ​​a rolling bearing according to the present invention;

[0074] Figure 6 Here is a structural diagram of the experimental setup;

[0075] Figure 7 The diagrams show the identification effect of the contact area under different working conditions. (a) shows the working condition with a speed of 600 rpm and a load of 86.25 N; (b) shows the working condition with a speed of 1000 rpm and a load of 86.25 N.

[0076] Figure 8 This is a comparison of theoretical calculations and experimental measurements of oil film thickness;

[0077] Figure 9 A schematic diagram of a computer device provided in an embodiment of the present invention;

[0078] Figure 10 This is a block diagram of a chip provided according to an embodiment of the present invention.

[0079] Among them, 1. Electric spindle; 2. Loading system; 3. Loading axis; 4. Tension sensor; 5. Bearing outer ring; 6. Servo motor; 7. Excitation pulse emission circuit; 8. Rectangular piezoelectric ceramic sensor; 60. Computer equipment; 61. Processor; 62. Memory; 63. Computer program; 600. Electronic equipment; 610. Processing unit; 620. Storage unit; 6201. Random access memory unit; 6202. Cache memory unit; 6203. Read-only memory unit; 6204. Program / utility; 6205. Program module; 630. Bus; 640. Display unit; 650. Input / output interface; 660. Network adapter; 700. External device. Detailed Implementation

[0080] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0081] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0082] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0083] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0084] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0085] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0086] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0087] This invention provides an embedded ultrasonic monitoring method for oil film thickness in the contact area of ​​rolling bearings. Addressing bottlenecks in existing technologies such as excitation source mismatch and insufficient real-time performance, the method derives excitation pulse parameters highly compatible with piezoelectric transducers through theoretical modeling. An excitation pulse transmitting circuit generates excitation pulses matched to the piezoelectric transducer. A parallel computing architecture combining asynchronous data streams and multi-channel pipelines is constructed based on FPGA, achieving microsecond-level response. A dual-threshold real-time positioning algorithm is proposed for reliable real-time identification of the contact area. This system achieves high-precision, high-resolution real-time monitoring of submicron oil film thickness in the rolling bearing contact area, forming a complete embedded solution with significant engineering value for improving the operational reliability of critical equipment and enabling predictive maintenance.

[0088] Please see Figure 1 The present invention discloses an embedded ultrasonic monitoring method for oil film thickness in the contact area of ​​a rolling bearing, comprising the following steps:

[0089] S1. In order to meet the requirements of non-destructive and high-resolution monitoring of oil film thickness in the contact area of ​​rolling bearings in the machine, a non-destructive testing method is adopted, in which a 1mm wide textured piezoelectric transducer patch is solidified on the surface of the rolling bearing. The core electrical parameters required for the excitation pulse are determined according to the resonant frequency of the piezoelectric transducer and the emitted sound pressure.

[0090] The core electrical parameters required for the excitation pulse are as follows:

[0091] S101. Based on the resonant frequency of the textured piezoelectric transducer patch, the resonant frequency of its thickness stretching vibration mode is determined through the admittance model of the textured piezoelectric transducer patch, as follows:

[0092]

[0093] in, f r It is the resonant frequency. f a It is the anti-resonant frequency. k t It is the electromechanical coupling coefficient. v D It is a textured piezoelectric transducer patch along z The speed of sound in a direction l t It refers to the thickness of the textured piezoelectric transducer patch. Based on the stated resonant frequency... f r The effective bandwidth range of the excitation pulse spectrum is determined, and then the excitation pulse width is determined. W ( t 0 , ) Scope of validity;

[0094] S102. Determine the expression for the sound pressure emitted by the textured piezoelectric transducer patch under the action of the excitation pulse, and the ultrasonic signal sound pressure. During the propagation process of the bearing component, its amplitude will decrease due to diffusion and other factors. This is related to the amplitude ratio between the excitation electrical pulse and the echo electrical signal. s The required energy of the excitation pulse is determined, and then the amplitude of the excitation pulse is calculated. V 0;

[0095] The sound pressure emitted by the textured piezoelectric transducer patch under the action of an excitation pulse is expressed as follows:

[0096]

[0097] in, It is the wavelength of the ultrasonic pressure in the medium; l It is the length of the piezoelectric transducer; l w It is the width of the piezoelectric transducer; K It is the wavenumber of the ultrasound. yes xoz Scattering angle on a plane; yes yoz Scattering angle on a plane; P 0 represents the sound pressure amplitude obtained from the initial excitation; r It is the distance between the diffusion location and the origin; s yes With initial sound pressure amplitude ratio, ; It is the amplitude of the excitation pulse.

[0098] S103. To ensure that the contact area of ​​each roller can reflect a number of effective ultrasonic echo signals, the repetition frequency of the excitation pulse needs to be determined based on the roller linear velocity. Therefore, the capacitor discharge time constant in the excitation pulse transmitting circuit... τ 0 meets the conditions, as follows:

[0099]

[0100] in, W It is the applied load. R ' It is the equivalent radius of curvature. m It is the number of valid ultrasonic echo signals collected when the roller passes through the piezoelectric transducer. v r It is the linear velocity of the roller. L It is the axial length of the roller. E ' It is the equivalent elastic modulus of the bearing contact pair.

[0101] Please see Figure 2 The diagram shows the excitation pulse emission circuit of the present invention. The high voltage power supply HV is used to provide a stable 200V high voltage. Its positive terminal is grounded, and its negative terminal is connected to one end of the energy storage capacitor C2 through the current limiting resistor R1 to provide negative high voltage energy for charging the capacitor.

[0102] The drain of the switching device MOSFET Q1 is connected to the other end of the energy storage capacitor C2, the source is grounded, and the gate is connected to an external control signal (a trigger signal from the FPGA) through the drive resistor R2 to control the charging and discharging state of the capacitor.

[0103] One end of the energy storage capacitor C2 is connected to the negative terminal of the high-voltage power supply via R1, and the other end is connected to the drain of the MOSFET Q1. At the same time, it is connected to the positive terminal of the piezoelectric transducer (Lead Zirconate Titanate, PZT) interface J1 through the output resistor R3. A freewheeling diode D1 is connected in parallel across the capacitor to protect the circuit from reverse voltage surges.

[0104] The piezoelectric transducer interface J1 uses a coaxial cable interface. Its positive terminal is connected to the connection node of the MOS transistor via R3 to C2, and its negative terminal is grounded. The other end of the interface is directly connected to the rectangular piezoelectric ceramic sensor 8 via a coaxial cable, which is used to transmit the generated negative high voltage spike pulse to the sensor.

[0105] R1 is the charging current limiting resistor, which limits the charging current of the high voltage power supply to C2; R2 is the gate drive resistor of the MOSFET, which stabilizes the control signal; R3 is the output current limiting resistor, which prevents the piezoelectric transducer from being damaged by excessive pulse current.

[0106] The excitation pulse emission circuit generates an excitation pulse signal that matches the required parameters of the textured piezoelectric transducer patch. Compared with conventional emission circuits, the excitation pulse signal generated by this circuit is highly matched to the requirements of the textured piezoelectric transducer patch, improving spatial resolution and enabling the system to detect submicron-level oil film thickness in the contact area.

[0107] S2. Based on the excitation pulse electrical parameters required by S1, excitation pulse signal parameters that are adapted to the height of the textured piezoelectric transducer patch are obtained through the design of the excitation pulse transmitting circuit.

[0108] The excitation pulse transmitting circuit is a negative high-voltage spike pulse transmitting circuit, and its output excitation pulse time-domain expression is as follows: v ( t )for:

[0109]

[0110] in, τ 0 is the capacitor discharge time constant; V 0 represents the absolute value of the pulse's peak value in the time domain;k It is the absolute value of the slope of the falling edge of the pulse.

[0111] Pulse width of the output excitation pulse W ( t 0 , The expression is:

[0112]

[0113] in, t 0 represents the fall time of the excitation pulse.

[0114] Spectrum of the output excitation pulse V ( ω The expression is:

[0115]

[0116] in, ω It is the angular frequency of the excitation pulse. ω =2π f v , f v The frequency of the excitation pulse.

[0117] Please see Figure 3 , Figure 3 (a) in the figure represents the high-voltage pulse signal emitted by the pulse excitation transmitting circuit over a period of time, with a repetition frequency of up to 100kHz. Figure 3 (b) in the middle is Figure 3 A magnified view of part (a) in the image, from Figure 3 As can be seen from (b), at the instant the MOS transistor Q1 is turned on, the voltage of the emitted pulse signal instantly becomes a negative voltage close to -180V, and the discharge time of the second capacitor C2 is 90ns, thus realizing high-resolution oil film thickness measurement in the contact area of ​​the rolling bearing at high speed.

[0118] S3. Considering the microsecond-level window period of the contact area of ​​the rolling bearing exposed to the sound field under high-speed operation, the ultrasonic echo signal is processed in parallel in the FPGA using a combination of asynchronous data stream and multi-channel pipeline, and the amplitude of the reflection coefficient of the rolling bearing contact area is calculated with a microsecond-level response speed.

[0119] Please see Figure 4 This is a schematic diagram of the parallel processing logic flow combining asynchronous data streams and multiple pipelines. In an optional embodiment of the present invention,

[0120] In a Field-Programmable Gate Array (FPGA), an asynchronous data stream-multiplexing approach is used to process ultrasonic echo signals in parallel and acquire the reflection coefficient amplitude in real time. Specifically, this includes:

[0121] Please see Figure 4 In (a), the film thickness calculation process is divided into multiple calculation stages with different real-time requirements. For the time-domain signal truncation and fast Fourier transform stage with the highest real-time requirements, a parallel processing logic combining asynchronous data flow and multi-channel pipeline is adopted. For the reflection coefficient calculation stage with relatively low real-time requirements, an asynchronous data flow architecture is used for processing.

[0122] The parallel processing logic combining asynchronous data streams and multi-pipelines includes:

[0123] Please see Figure 4 In (b), the Fast Fourier Transform (FFT) module is isolated from the upstream and downstream processing modules by an asynchronous FIFO in the clock domain. The FFT module is accelerated by using a higher operating frequency independent of the system clock. Parallel computing pipelines are configured so that when one pipeline is in operation, subsequent computing tasks can be immediately taken over and executed by other idle pipelines.

[0124] Asynchronous data stream architecture includes:

[0125] An asynchronous FIFO is set up between the Fast Fourier Transform module and the reflection coefficient calculation module for data buffering.

[0126] Configuring multiple parallel computing pipelines includes:

[0127] Establish at least two Fast Fourier Transform (FFT) calculation pipelines. When the first pipeline is performing FFT calculations, if new time-domain truncation data arrives, the second pipeline will immediately begin processing it. When subsequent data arrives, the pipeline that completed the calculation first and is in an idle state will take over the processing task.

[0128] Reflection coefficient amplitude | R ( f The expression is:

[0129]

[0130] in, S ( f The signal spectrum is the echo signal when the oil film is present. A ( f () represents the spectrum of the reflected signal at the raceway-air interface. V ref The reflection coefficient is the raceway-air interface coefficient.

[0131] S4. Based on the amplitude variation characteristics of the reflection coefficient waveform curve in S3, the contact area position of the rolling bearing is automatically located on the real-time waveform, and the oil film thickness value of the contact area is calculated using the amplitude of the reflection coefficient at that position.

[0132] Please see Figure 5 The steps for automatically positioning the contact area of ​​a rolling bearing are as follows:

[0133] A real-time positioning algorithm for the contact area of ​​a rolling bearing with dual thresholds is used to automatically locate the contact area of ​​the rolling bearing in real time and calculate the oil film thickness. Specifically:

[0134] Monitor the change in the amplitude of the reflection coefficient at the center frequency of the piezoelectric transducer as the roller passes by; identify the start time when the amplitude of the reflection coefficient changes from a stable state to a fluctuating state, and the end time when it recovers from the fluctuating state to a stable state; calculate the position of the contact area based on the start time and end time, and calculate the oil film thickness of the contact area based on the located reflection coefficient amplitude.

[0135] The start and end times identified in the real-time positioning algorithm for the contact area of ​​a dual-threshold rolling bearing include:

[0136] The amplitude of the reflection coefficient is limited, and values ​​with an amplitude greater than 1 are set to 1. The processed reflection coefficient amplitude data is traversed, and when the amplitude changes from 1 to less than 1, it is marked as the start time. The reflection coefficient amplitude data is traversed again, and when the amplitude changes from less than 1 to 1, it is marked as the end time.

[0137] The preliminary determination of the location of the contact area includes:

[0138] Calculate the time difference between the end time and the start time, compare the time difference with a preset time threshold, and determine that the initial search is correct when the time difference is greater than the time threshold.

[0139] The final determination of the location of the contact area includes:

[0140] The reflection coefficient amplitude corresponding to the midpoint between the start and end times is obtained. The reflection coefficient amplitude is compared with a preset amplitude threshold. When the reflection coefficient amplitude is less than the amplitude threshold, it is finally determined that the contact area has been found correctly, and the reflection coefficient amplitude is used as the reflection coefficient amplitude of the contact area.

[0141] Oil film thickness h The calculation expression is:

[0142]

[0143] in, ρ 2 is the density of the lubricating medium. c 2 is the speed of sound in the lubricating medium. f It is the frequency of the sound wave, usually selected as the center frequency of the transducer. z This refers to the acoustic impedance of the medium. Subscripts 1 and 3 represent the friction pair materials on both sides of the lubricating medium, and 2 represents the lubricating medium layer. R ( f )| is the amplitude of the reflection coefficient at the center frequency of the contact area.

[0144] In another embodiment of the present invention, an embedded ultrasonic monitoring system for oil film thickness in the contact area of ​​a rolling bearing is provided. This system can be used to implement the above-mentioned embedded ultrasonic monitoring method for oil film thickness in the contact area of ​​a rolling bearing. Specifically, the embedded ultrasonic monitoring system for oil film thickness in the contact area of ​​a rolling bearing includes a parameter module, a pulse module, a signal module, and a calculation module.

[0145] Among them, the parameter module adopts a non-destructive testing method in which textured piezoelectric transducer patches are solidified on the surface of rolling bearings. The core electrical parameters required for the excitation pulse are determined based on the resonant frequency of the textured piezoelectric transducer patch and the emitted sound pressure.

[0146] The pulse module generates an excitation pulse signal that matches the textured piezoelectric transducer patch through the excitation pulse transmitting circuit, based on the core electrical parameters required for the excitation pulse obtained from the parameter module.

[0147] The signal module inputs the excitation pulse signal generated by the pulse module to the textured piezoelectric transducer patch to generate ultrasonic waves, receives the ultrasonic echo signal reflected by the rolling bearing contact area, and processes the ultrasonic echo signal in parallel in the field programmable gate array (FPGA) using an asynchronous data stream-multiplexing approach to obtain the amplitude of the reflection coefficient of the rolling bearing contact area.

[0148] The calculation module uses a dual-threshold algorithm to automatically locate the contact area of ​​the rolling bearing in real time based on the reflection coefficient amplitude of the rolling bearing contact area obtained from the signal module, and calculates the oil film thickness of the contact area according to the reflection coefficient amplitude corresponding to the located contact area.

[0149] This invention provides a terminal device comprising a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, graphics processing units (GPUs), tensor processing units (TPUs), digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions to achieve a corresponding method flow or corresponding function. The processor described in this embodiment can be used in the operation of an embedded ultrasonic monitoring method for the oil film thickness in the contact area of ​​rolling bearings, including:

[0150] A non-destructive testing method is adopted, in which a textured piezoelectric transducer patch is solidified on the surface of a rolling bearing. The core electrical parameters required for the excitation pulse are determined based on the resonant frequency and emitted sound pressure of the textured piezoelectric transducer patch. Based on these parameters, an excitation pulse signal matching the textured piezoelectric transducer patch is generated by an excitation pulse transmitting circuit. The generated excitation pulse signal is input to the textured piezoelectric transducer patch to generate ultrasonic waves. Ultrasonic echo signals reflected from the rolling bearing contact area are received, and these echo signals are processed in parallel using an asynchronous data stream-multiplexing pipeline in a field-programmable gate array (FPGA) to obtain the reflection coefficient amplitude of the rolling bearing contact area. Based on this amplitude, a dual-threshold algorithm is used to automatically locate the rolling bearing contact area in real time, and the oil film thickness of the contact area is calculated based on the corresponding reflection coefficient amplitude.

[0151] Please see Figure 9The terminal device is a computer device. In this embodiment, the computer device 60 includes a processor 61, a memory 62, and a computer program 63 stored in the memory 62 and executable on the processor 61. When executed by the processor 61, the computer program 63 implements the embedded ultrasonic monitoring method for oil film thickness in the rolling bearing contact area as described in this embodiment. To avoid repetition, these details are not elaborated here. Alternatively, when executed by the processor 61, the computer program 63 implements the functions of each model / unit in the embedded ultrasonic monitoring system for oil film thickness in the rolling bearing contact area as described in this embodiment. To avoid repetition, these details are not elaborated here.

[0152] Computer device 60 can be a desktop computer, laptop, handheld computer, cloud server, or other computing device. Computer device 60 may include, but is not limited to, a processor 61 and a memory 62. Those skilled in the art will understand that... Figure 9 This is merely an example of computer device 60 and does not constitute a limitation on computer device 60. It may include more or fewer components than shown, or combine certain components, or different components. For example, computer device may also include input / output devices, network access devices, buses, etc.

[0153] The processor 61 may be a Central Processing Unit (CPU), or other general-purpose processors, graphics processing units (GPUs), tensor processing units (TPUs), digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0154] The memory 62 can be an internal storage unit of the computer device 60, such as a hard disk or memory of the computer device 60. The memory 62 can also be an external storage device of the computer device 60, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc. equipped on the computer device 60.

[0155] Furthermore, the memory 62 may include both internal storage units and external storage devices of the computer device 60. The memory 62 is used to store computer programs and other programs and data required by the computer device. The memory 62 can also be used to temporarily store data that has been output or will be output.

[0156] Please see Figure 10 The terminal device is an electronic device 600, which is manifested in the form of a general-purpose computing device. The components of the electronic device may include, but are not limited to: at least one processing unit 610, at least one storage unit 620, a bus 630 connecting different platform components (including storage unit 620 and processing unit 610), a display unit 640, etc.

[0157] The storage unit stores program code, which can be executed by the processing unit 610 to perform the steps described in the method section of this specification according to various exemplary embodiments of the present invention. For example, the processing unit 610 can perform actions such as... Figure 1 The steps are shown in the figure.

[0158] Storage unit 620 may include a readable medium in the form of a volatile storage unit, such as random access memory (RAM) 6201 and / or cache memory 6202, and may further include a read-only memory (ROM) 6203.

[0159] Storage unit 620 may also include a program / utility 6204 having a set (at least one) program module 6205, such program module 6205 including but not limited to: operating system, one or more application programs, other program modules and program data, each or some combination of these examples may include an implementation of a network environment.

[0160] Bus 630 can represent one or more of several types of bus structures, including a memory cell bus or memory cell controller, a peripheral bus, a graphics acceleration port, a processing unit, or a local bus using any of the multiple bus structures.

[0161] Electronic device 600 can also communicate with one or more external devices 700 (e.g., keyboard, pointing device, Bluetooth device, etc.), and with one or more devices that enable a user to interact with electronic device 600, and / or with any device that enables electronic device 600 to communicate with one or more other computing devices (e.g., router, modem). This communication can be performed via input / output interface 650. Furthermore, electronic device 600 can also communicate with one or more networks (e.g., local area network, wide area network, and / or public network, such as the Internet) via network adapter 660. Network adapter 660 can communicate with other modules of electronic device 600 via bus 630. It should be understood that, although not shown in the figures, other hardware and / or software modules can be used in conjunction with electronic device 600, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms.

[0162] Example 4

[0163] This invention also provides a storage medium, specifically a computer-readable storage medium, which is a memory device in a terminal device for storing programs and data. It is understood that the computer-readable storage medium here can include both built-in storage media in the terminal device and extended storage media supported by the terminal device; it can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, the storage space also stores one or more instructions suitable for loading and execution by a processor, which can be one or more computer programs (including program code). More specific examples of the computer-readable storage medium include: an electrical connection with one or more wires, a portable disk, a hard disk, random access memory, read-only memory, erasable programmable read-only memory, optical fiber, portable compact disk read-only memory, optical storage device, magnetic storage device, or any suitable combination thereof.

[0164] Computer-readable storage media also include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable storage medium can also be any readable medium other than a readable storage medium that can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the readable storage medium can be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, radio frequency, etc., or any suitable combination thereof.

[0165] Program code for performing the operations of this invention can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can execute entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0166] One or more instructions stored in a computer-readable storage medium can be loaded and executed by a processor to implement the corresponding steps of the embedded ultrasonic monitoring method for oil film thickness in the rolling bearing contact area in the above embodiments; one or more instructions in the computer-readable storage medium are loaded and executed by the processor to perform the following steps:

[0167] A non-destructive testing method is adopted, in which a textured piezoelectric transducer patch is solidified on the surface of a rolling bearing. The core electrical parameters required for the excitation pulse are determined based on the resonant frequency and emitted sound pressure of the textured piezoelectric transducer patch. Based on these parameters, an excitation pulse signal matching the textured piezoelectric transducer patch is generated by an excitation pulse transmitting circuit. The generated excitation pulse signal is input to the textured piezoelectric transducer patch to generate ultrasonic waves. Ultrasonic echo signals reflected from the rolling bearing contact area are received, and these echo signals are processed in parallel using an asynchronous data stream-multiplexing pipeline in a field-programmable gate array (FPGA) to obtain the reflection coefficient amplitude of the rolling bearing contact area. Based on this amplitude, a dual-threshold algorithm is used to automatically locate the rolling bearing contact area in real time, and the oil film thickness of the contact area is calculated based on the corresponding reflection coefficient amplitude.

[0168] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0169] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0170] Application examples

[0171] Please see Figure 6 The effectiveness of the method of the present invention was verified by using a rolling and sliding test bench. The test device consists of five parts: test bearing, loading system, servo drive system, industrial control computer and lubrication system.

[0172] The electric spindle 1 is connected to the servo motor 6, which drives the electric spindle 1 to rotate the inner ring of the rolling bearing. The outer ring 5 of the bearing is fixedly installed, and the rectangular piezoelectric ceramic sensor 8 is bonded to the outer surface of the outer ring 5 by curing. It is used to emit ultrasonic signals and receive echo signals. The loading system 2 is connected to the tension sensor 4 through the loading shaft 3. The output end of the tension sensor 4 abuts against the side of the outer ring 5 of the bearing. The loading system 2 applies a preset load through the loading shaft 3 and the tension sensor 4 monitors the load magnitude in real time. The excitation pulse emission circuit 7 is electrically connected to the rectangular piezoelectric ceramic sensor 8 through a coaxial cable to provide the sensor with an excitation pulse signal. The excitation pulse emission circuit 7 communicates bidirectionally with the FPGA (not marked in the figure, belonging to the signal processing unit). The FPGA receives the ultrasonic echo signal transmitted by the rectangular piezoelectric ceramic sensor 8 and performs parallel processing. All components work together to form a complete experimental monitoring system.

[0173] Its operating principle is as follows: the loading system 2 applies a load to the outer ring 5 of the bearing and keeps the outer ring 5 stationary; the industrial control computer on the experimental platform controls the servo motor to drive the inner ring of the bearing to rotate at different speeds; and the peristaltic pump sprays lubricating oil onto the raceway between the rollers and the outer ring 5 of the bearing. The experimental bearing model is a standard bearing with a flange on the outer ring, NF211EM.

[0174] The excitation pulse emission circuit used in the experiment had a repetition frequency of 125 kHz, a high voltage (HV) of 200 V, an ADC sampling frequency of 500 MHz, and a Xilinx XCZU15EG-2FFVB1156I FPGA core board. Furthermore, a small, easily cut, and conveniently fitted rectangular piezoelectric ceramic sensor 8 was used for measurement. It was obtained by cutting a 7 mm diameter PZT-5H piezoelectric transducer, with a width of 1 mm and a thickness of 0.2 mm.

[0175] Please see Figure 7 The effectiveness of the rolling bearing contact area positioning algorithm was verified through experiments. Figure 7 Image (a) shows the reflection coefficient amplitude at the center frequency and the identification effect of the contact area under the working conditions of 600 rpm and 86.25 N load. Figure 7 Figure (b) shows the reflection coefficient amplitude at the center frequency and the identification effect of the contact area under the conditions of 1000 rpm and 86.25 N load. The results show that the contact area can be accurately identified under both conditions. As the rotational speed increases, the number of contact areas also increases within the same time length, but the characteristics of the contact areas remain consistent. This not only proves the accuracy of the contact area localization algorithm, but also further demonstrates its applicability and robustness. Furthermore, based on the parallel processing method of asynchronous data stream and multi-channel pipeline fusion, it has the ability to maintain stable real-time processing at a high repetition frequency of 125 kHz.

[0176] Please see Figure 8 The reliability of oil film thickness monitoring for rolling bearings was verified by comparing the theoretically calculated oil film thickness in the contact area with the oil film thickness calculated from the reflection coefficient amplitude obtained from experimentally positioned contact areas. The figure shows the comparison results between the theoretical calculation and actual monitoring. The results show that the measured values ​​and theoretical values ​​have good consistency, with an absolute error of less than 0.2 μm. This indicates that the method of the present invention can achieve high-resolution, high-precision real-time oil film thickness monitoring, providing a reliable technical means for the condition monitoring of rolling bearings.

[0177] In summary, this invention provides an embedded ultrasonic monitoring method and system for the oil film thickness in the contact area of ​​rolling bearings. Starting from the working mechanism of piezoelectric transducers, it reverse-engineers the excitation pulse parameters that are highly compatible with the piezoelectric transducers, thus solving the bottleneck of insufficient spatial resolution caused by the mismatch between the excitation pulse and the piezoelectric transducer in existing technologies. Simultaneously, a parallel processing architecture combining asynchronous data streams and multi-channel pipelines is employed in an FPGA to achieve real-time automatic positioning and film thickness calculation of the contact area, overcoming the limitation of poor real-time computing performance. Experimental results show that this method and system can accurately identify the contact area, and the absolute error between the measured film thickness and the theoretical value is less than 0.2 μm. It can still operate stably at a high repetition frequency of 125 kHz, providing an effective solution for accurate, on-machine, and real-time monitoring of the lubrication status of rolling bearings.

[0178] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0179] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0180] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed in this invention can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0181] In the embodiments provided by this invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0182] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0183] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0184] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random-access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0185] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus, and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0186] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0187] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0188] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. An embedded ultrasonic monitoring method for oil film thickness in the contact area of ​​a rolling bearing, characterized in that, Includes the following steps: S1. A non-destructive testing method using textured piezoelectric transducer patches cured on the surface of a rolling bearing. The core electrical parameters required for the excitation pulse are determined based on the resonant frequency and emitted sound pressure of the textured piezoelectric transducer patch. The specific process includes: S101. Based on the admittance model of the piezoelectric transducer, determine the resonant frequency of its thickness stretching vibration mode, and determine the effective bandwidth range of the excitation pulse spectrum according to the resonant frequency to obtain the effective range of the excitation pulse width. S102. Based on the effective range of the excitation pulse width determined in S101, the amplitude of the excitation pulse is determined by the expression of the sound pressure emitted by the piezoelectric transducer under the action of the excitation pulse, combined with the amplitude ratio between the excitation electrical pulse and the echo electrical signal. S103. Determine the repetition frequency of the excitation pulse based on the roller linear velocity. Combined with the excitation pulse amplitude obtained in S102 and the bearing operating parameters, determine the capacitor discharge time constant in the excitation pulse transmitting circuit. τ 0, so that the contact area of ​​each roller can reflect a number of effective ultrasonic echo signals; S2. Based on the core electrical parameters required for the excitation pulse obtained in S1, an excitation pulse signal matching the textured piezoelectric transducer patch is generated through the excitation pulse transmitting circuit. S3. The excitation pulse signal generated in S2 is input to the textured piezoelectric transducer patch to generate ultrasonic waves. The ultrasonic echo signal reflected from the rolling bearing contact area is received, and the ultrasonic echo signal is processed in parallel in a field-programmable gate array (FPGA) using an asynchronous data stream-multiplexing pipeline approach to obtain the amplitude of the reflection coefficient of the rolling bearing contact area. The parallel processing using an asynchronous data stream-multiplexing pipeline approach specifically includes: The process of calculating the reflection coefficient amplitude is divided into a time-domain signal truncation stage, a fast Fourier transform stage, and a reflection coefficient calculation stage. For the time-domain signal truncation stage and the fast Fourier transform stage, a parallel processing logic combining asynchronous data streams and multiple pipelines is adopted. The parallel processing logic includes clock domain isolation through an asynchronous first-in-first-out queue (FIFO), acceleration of operation by using a higher operating frequency, and configuration of at least two parallel operation pipelines to achieve immediate takeover of the operation task. An asynchronous data flow architecture is used to process the reflection coefficient calculation stage. S4. Based on the reflection coefficient amplitude of the rolling bearing contact area obtained in S3, the contact area of ​​the rolling bearing is automatically located in real time using a dual threshold algorithm, and the oil film thickness of the contact area is calculated according to the reflection coefficient amplitude corresponding to the located contact area.

2. The embedded ultrasonic monitoring method for oil film thickness in the contact area of ​​a rolling bearing according to claim 1, characterized in that, In S102, the sound pressure emitted by the piezoelectric transducer The expression is: in, It is the wavelength of the ultrasonic sound pressure in the medium; l It is the length of the piezoelectric transducer; l w It is the width of the piezoelectric transducer; K It is the wavenumber of the ultrasound. yes xoz Scattering angle on a plane; yes yoz Scattering angle on a plane; P 0 represents the sound pressure amplitude obtained from the initial excitation; r It is the distance between the diffusion location and the origin; s It is the sound pressure emitted by the piezoelectric transducer and the initial sound pressure. The amplitude ratio.

3. The embedded ultrasonic monitoring method for oil film thickness in the contact area of ​​a rolling bearing according to claim 1, characterized in that, In S103, the capacitor discharge time constant in the excitation pulse emission circuit τ 0 is: in, W It is the applied load. R ' It is the equivalent radius of curvature. m It is the number of valid ultrasonic echo signals collected when the roller passes through the piezoelectric transducer. v r It is the linear velocity of the roller. L It is the axial length of the roller. E ' It is the equivalent elastic modulus of the bearing contact pair.

4. The embedded ultrasonic monitoring method for oil film thickness in the contact area of ​​a rolling bearing according to claim 1, characterized in that, In S2, the excitation pulse transmitting circuit is a negative high-voltage spike pulse transmitting circuit, and its output excitation pulse is in the time domain. v ( t )for: Pulse width of the output excitation pulse W ( t 0 , )for: Spectrum of the output excitation pulse V ( ω )for: in, τ 0 represents the capacitor discharge time constant. V 0 represents the absolute value of the pulse's time-domain peak value. k This is the absolute value of the slope of the falling edge of the pulse; t 0 represents the fall time of the excitation pulse; t It is a time variable; j It is the imaginary unit; ω It is the angular frequency of the excitation pulse; e It is a natural constant.

5. The embedded ultrasonic monitoring method for oil film thickness in the contact area of ​​a rolling bearing according to claim 1, characterized in that, In S3, the amplitude of the reflection coefficient | R ( f )| is: in, S ( f The signal spectrum is the echo signal when the oil film is present. A ( f () represents the spectrum of the reflected signal at the raceway-air interface. V ref The reflection coefficient is the raceway-air interface coefficient.

6. The embedded ultrasonic monitoring method for oil film thickness in the contact area of ​​a rolling bearing according to claim 1, characterized in that, In S4, the real-time automatic positioning of the contact area of ​​the rolling bearing using a dual-threshold algorithm specifically includes: Monitor the amplitude change of the reflection coefficient at the center frequency of the piezoelectric transducer; The amplitude of the reflection coefficient is limited, and values ​​with an amplitude greater than 1 are set to 1; Traverse the processed data, and mark the start time when the amplitude changes from 1 to less than 1, and mark the end time when the amplitude changes from less than 1 to 1. The location of the contact area is determined based on the start and end times.

7. The embedded ultrasonic monitoring method for oil film thickness in the contact area of ​​a rolling bearing according to claim 6, characterized in that, The determination of the location of the contact area specifically includes: Calculate the time difference between the end time and the start time, and make a preliminary judgment when the time difference is greater than a preset time threshold; The reflection coefficient amplitude corresponding to the midpoint between the start and end times is obtained. When the reflection coefficient amplitude is less than a preset amplitude threshold, a final determination is made and the location of the contact area is confirmed.

8. An embedded ultrasonic monitoring system for oil film thickness in the contact area of ​​a rolling bearing, characterized in that, include: The parameter module employs a non-destructive testing method where textured piezoelectric transducer patches are solidified onto the surface of a rolling bearing. Based on the resonant frequency and emitted sound pressure of the textured piezoelectric transducer patch, the core electrical parameters required for the excitation pulse are determined. The specific process for determining these core electrical parameters includes: The resonant frequency of the thickness stretching vibration mode of the piezoelectric transducer is determined based on its admittance model. The effective bandwidth range of the excitation pulse is then determined based on this resonant frequency, thus obtaining the effective range of the excitation pulse width. Based on the determined effective range of the excitation pulse width, the amplitude of the excitation pulse is determined by using the expression for the sound pressure emitted by the piezoelectric transducer under the action of the excitation pulse, combined with the amplitude ratio between the excitation pulse and the echo signal. The repetition frequency of the excitation pulse is determined based on the roller linear velocity. Combined with the obtained excitation pulse amplitude and bearing operating parameters, the capacitor discharge time constant in the excitation pulse transmitting circuit is determined. τ 0, so that the contact area of ​​each roller can reflect a number of effective ultrasonic echo signals; The pulse module generates an excitation pulse signal that matches the textured piezoelectric transducer patch through the excitation pulse transmitting circuit, based on the core electrical parameters required for the excitation pulse obtained from the parameter module. The signal module inputs the excitation pulse signal generated by the pulse module to the textured piezoelectric transducer patch to generate ultrasonic waves, receives the ultrasonic echo signal reflected from the rolling bearing contact area, and processes the ultrasonic echo signal in parallel in a field-programmable gate array (FPGA) using an asynchronous data stream-multiplexing pipeline approach to obtain the amplitude of the reflection coefficient of the rolling bearing contact area. The parallel processing using an asynchronous data stream-multiplexing pipeline approach specifically includes: The reflection coefficient amplitude calculation process is divided into a time-domain signal truncation stage, a fast Fourier transform stage, and a reflection coefficient calculation stage. For the time-domain signal truncation stage and the fast Fourier transform stage, a parallel processing logic combining asynchronous data flow and multi-channel pipelines is adopted. The parallel processing logic includes clock domain isolation through an asynchronous first-in-first-out queue (FIFO), acceleration of operation by using a higher operating frequency, and configuration of at least two parallel operation pipelines to achieve immediate takeover of the operation task. For the reflection coefficient calculation stage, an asynchronous data flow architecture is used for processing. The calculation module uses a dual-threshold algorithm to automatically locate the contact area of ​​the rolling bearing in real time based on the reflection coefficient amplitude of the rolling bearing contact area obtained from the signal module, and calculates the oil film thickness of the contact area according to the reflection coefficient amplitude corresponding to the located contact area.

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