Method and system for continuous detection of full-scale lubricating film thickness using ultrasonic reflection coefficient phase spectrum
A reflection coefficient, lubricating film technology, applied in the direction of using ultrasonic/sonic/infrasonic waves, measuring devices, instruments, etc., can solve the problem of inability to achieve continuous monitoring of full-scale oil film thickness, and achieve the effect of continuous measurement
Active Publication Date: 2019-10-11
XI AN JIAOTONG UNIV
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Therefore, when the thickness of the lubrication film of the friction pair changes continuously on a large scale, the continuous monitoring of the full-scale oil film thickness cannot be realized by using a single center frequency sensor
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[0051] The present invention will be further described below in conjunction with drawings and embodiments.
[0052] When the ultrasonic wave propagates in the three-layer medium (substrate A-lubricating film-substrate B), the phase expression of the reflection coefficient of the middle layer is:
[0053]
[0054] Among them, R 12 , R 23 are the displacement reflection coefficients of the substrate B-lubricating film interface and the lubricant film-substrate A interface, respectively, and the substrate A is the substrate on the ultrasonic incident side; c 2 is the speed of sound in lubricating oil; β is the attenuation factor of ultrasonic waves in lubricating oil, φ is the reflection coefficient phase angle, f is the ultrasonic (sensor) frequency; d is the oil film thickness; R 12 and R 23 Expressed as:
[0055]
[0056] where Z i (Z i = ρ i c i ) are the acoustic impedance of medium i, i=1, 2, 3 respectively correspond to matrix B, lubricating film, matrix A, ρ...
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The invention discloses a method and system utilizing an ultrasonic reflection coefficient phase spectrum for continuous detection of whole scale lubrication film thickness. When a mutational zero crossing point appears in the reflection coefficient phase spectrum, frequency of the zero crossing point is extracted as resonant frequency for calculating the oil film thickness. When no mutational zero crossing point appears in the reflection coefficient phase spectrum, the oil film thickness is calculated according to the phase at the central frequency of an ultrasonic wave sensor. The inventionis characterized in that a problem of dead zone identification of a spring model method and a resonance method in prior ultrasonic detection is solved and all measurement ranges of a prior ultrasonicdetection model can be covered, so that continuous monitoring of oil film thickness of large scale range change is realized.
Description
technical field [0001] The invention belongs to the technical field of lubricating state detection of friction pairs of machine systems, and relates to an ultrasonic detection method for large-scale variation of lubricating film thickness. Background technique [0002] During the operation of the friction pair, poor lubrication often leads to the rupture of the lubricating film, and the relative moving surfaces will contact, friction, wear and bite. Therefore, the lubricating film thickness is a key parameter reflecting the lubrication state. When the machine is in the start-stop phase or subjected to impact loads, the thickness of the lubricating film between the friction pairs will vary in a wide range. Therefore, in order to ensure the stable and safe operation of the machine, it is necessary to conduct online full-scale continuous monitoring of the lubricating film thickness between the friction pairs. [0003] The thickness of the lubricating film between friction pai...
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IPC IPC(8): G01B17/02
Inventor 武通海窦潘罗朝鹏
Owner XI AN JIAOTONG UNIV