Lubricating oil performance diagnostic method and performance diagnostic device

Abstract

To make it possible to simultaneously quantitatively evaluate each form of degradation, such as oxidative degradation, additive depletion, moisture and abrasion powder contamination with a single device.SOLUTION: Terahertz waves are irradiated to lubricant L using an irradiation device, the transmitted waves transmitted through the lubricant L or the reflected waves reflected from the lubricant L are acquired by a detection device 40, and based on the acquired data, a plurality of parameters are calculated and at least two of the parameters including viscosity, a degree of oxidation, additive consumption, moisture content, and metal abrasion powder content of the lubricant L are separated and identified using the plurality of calculated parameters. In such a performance diagnostic method for the lubricant, data may be acquired by terahertz time-domain spectroscopy, and a plurality of parameters may be calculated based on the acquired data.SELECTED DRAWING: Figure 3C

Description

[Technical Field]

[0001] The present invention relates to a method and an apparatus for diagnosing the performance of a lubricating oil. [Background technology]

[0002] Rotating equipment often requires condition monitoring technology to detect signs of abnormalities early during operation in order to prevent damage. Lubricants are one of the key elements for the smooth operation of mechanical components in rotating equipment. Oxidation and deterioration of lubricant base oils, as well as contamination with foreign matter such as water or metal wear particles, can lead to a decline in lubricating performance, resulting in increased wear on component parts and ultimately equipment damage. For this reason, it is important to monitor and accurately diagnose the condition of lubricants, particularly the degree of deterioration, when monitoring the condition of rotating equipment.

[0003] In diagnosing the deterioration state of such lubricating oil, the following items are generally monitored: Oxidative deterioration of base oil Consumption of additives such as antioxidants - Moisture contamination -Contamination of metal wear particles For example, the oxidation and deterioration of base oil, the consumption of additives, and the inclusion of water cause a decrease in lubrication performance. In addition, metal wear particles in lubricating oil are generally hard, which accelerates the wear of sliding surfaces. All of these are important pieces of information, and there is a demand for technology that can easily monitor them in operating equipment. In fact, conventional technologies for monitoring these items include: -Technology for measuring the degree of oxidation degradation of lubricating oil using infrared absorption spectroscopy (see, for example, Patent Document 1) A technique for measuring the amount of additives (antioxidants) using infrared absorption spectroscopy (see, for example, Patent Document 2), or a technique for passing visible light (white light) through a target and measuring the additive concentration based on the color data of the transmitted light (see, for example, Patent Document 3). A technology that passes visible light (white light) through a target and measures the moisture content based on the color data of the transmitted light (see, for example, Patent Document 4) A technology that passes visible light (white light) through a target and measures the amount of metal wear debris based on the color data of the transmitted light (see, for example, Patent Document 5) Examples include: [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-028793 [Patent Document 2] Japanese Patent Application Publication No. 08-226896 [Patent Document 3] Japanese Patent Application Publication No. 2019-078718 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-156170 [Patent Document 5] Japanese Patent Application Publication No. 2017-102052 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in actual equipment, multiple degradation phenomena such as oxidation degradation, water contamination, and metal powder contamination occur simultaneously, and conventional technologies that target a single monitoring item make it difficult to identify and quantitatively evaluate these.

[0006] Therefore, an object of the present invention is to provide a lubricating oil performance diagnostic method and device that can simultaneously quantitatively evaluate each phenomenon, such as oxidative degradation, additive consumption, and the inclusion of water and wear particles. [Means for solving the problem]

[0007] To solve the above problems, the inventors focused on terahertz waves, which have a strong penetrating power for organic matter, and investigated how to irradiate lubricating oil with terahertz waves and identify the type and degree of deterioration of the lubricating oil based on information from the transmitted waves, etc. As a result, they discovered that by using multiple measurement parameters, it is possible to accurately separate and identify various characteristics of the lubricating oil, such as the viscosity, degree of oxidative deterioration, amount of additive consumption, and amount of moisture and metal powder contamination.

[0008] One aspect of the present invention based on this finding is a performance diagnostic method for diagnosing the performance of a lubricating oil, comprising: The lubricant is irradiated with terahertz waves using an irradiation device. A detection device acquires transmitted waves that have passed through the lubricating oil or reflected waves that have been reflected from the lubricating oil. Calculating a plurality of parameters based on the acquired data; This is a lubricant performance diagnostic method that uses multiple calculated parameters to separate and identify at least two of the lubricant's viscosity, degree of oxidation, additive consumption, water content, and amount of metal wear particles.

[0009] Terahertz waves (typically 0.1 THz to 10 THz or 30 μm to 3 mm wavelength) have a longer wavelength than visible light (360 nm to 830 nm) or infrared light (2.5 μm to 25 μm), which have traditionally been used for lubricant oil measurement. These characteristics allow stable transmission measurements even through deteriorated lubricants that are difficult for visible light or infrared light to penetrate. Furthermore, because terahertz waves are highly permeable to resin materials, non-contact measurements with the lubricant can be performed using a resin measurement container. This allows measurements to be performed without contaminating the sensor surface. Using multiple measurement parameters acquired using terahertz waves, it is possible to separate and identify various characteristics of lubricant oil, such as oxidation degradation, additive depletion, and the presence of moisture or metal wear particles.

[0010] As parameters for the lubricant performance diagnostic method described above, a reference waveform representing a reference state may be a transmitted waveform or a reflected waveform obtained by irradiating terahertz waves when there is no lubricant or when the lubricant is not deteriorated, and a sample waveform may be a transmitted waveform or a reflected waveform obtained by irradiating terahertz waves onto the lubricant to be measured, and a value calculated from both the reference waveform and the sample waveform may be used.

[0011] In the above-described lubricant performance diagnostic method, a correction waveform may be obtained along with the sample waveform, and output fluctuations may be corrected based on the correction waveform.

[0012] In the above-described lubricant performance diagnostic method, terahertz wave irradiation and data acquisition may be repeated, and the acquired data or multiple parameter statistics calculated based on the acquired data may be used as parameters.

[0013] In the above-described method for diagnosing the performance of lubricating oil, data acquisition may be repeated while changing the irradiation position of the terahertz waves.

[0014] In the above-described lubricant performance diagnostic method, a calibration curve may be defined for each type of lubricant to be measured based on data obtained by previously measuring the relationship between various characteristics and parameters related to the performance of the lubricant, and the calibration curve may be used as the basis for performance diagnostics.

[0015] In the above-described method for diagnosing lubricant performance, a tolerance value for the rate of change from the initial state of the lubricant may be set for each parameter, and the presence or absence of an abnormality in the lubricant may be determined based on the tolerance value.

[0016] In the lubricant performance diagnostic method as described above, for example, for each index indicating the characteristics of the lubricant performance, the deterioration rate is calculated from the deterioration level of the lubricant at the time of detection and the period of use. Deterioration rate at the time of detection = Deterioration level at the time of measurement / Duration of use It may be calculated based on the following.

[0017] In the above-described method for diagnosing lubricant performance, the remaining life of the lubricant may be calculated as the time until the rate of deterioration or the change in deterioration over time reaches a predetermined limit value.

[0018] In the above-described method for diagnosing lubricant performance, the shortest time among the times until the respective limit values ​​of the multiple deterioration rates calculated for each index are reached may be calculated as the remaining life of the lubricant.

[0019] In the above-described method for diagnosing lubricant performance, data may be acquired by terahertz time-domain spectroscopy, and a plurality of parameters may be calculated based on the acquired data.

[0020] In the above-mentioned lubricating oil performance diagnostic method, for example, by taking the ratio of the amplitude of the reference waveform to that of the sample waveform, the transmittance when the reference state is used as the standard can be calculated. Transmittance = Sample waveform amplitude / Reference waveform amplitude and may be used as one of a plurality of parameters.

[0021] In the above-mentioned lubricating oil performance diagnostic method, for example, by taking the difference in the appearance time of the peak value of the reference waveform and the sample waveform, the peak time difference when the reference state is used as the standard can be calculated. Peak time difference = Sample waveform peak time - Reference waveform peak time and may be used as one of a plurality of parameters.

[0022] In the above-described lubricant performance diagnostic method, for example, the optical path length and the light speed of the irradiated terahertz wave are used to determine the lubricant performance. Refractive index = Peak time difference·Speed ​​of light / Optical path length The refractive index may be converted into a refractive index by the following equation, and the refractive index may be used as one of the parameters.

[0023] In the lubricating oil performance diagnosis method described above, for example, the reference waveform and the sample waveform may each be Fourier transformed to obtain amplitude and phase information for each frequency, and the transmittance and refractive index for each frequency may be calculated based on this information, with the value at a specific frequency or the average value for a specific section being used as one of the multiple parameters.

[0024] In the lubricant performance diagnostic method as described above, for example, the ratio of the standard deviations of the amplitudes of a plurality of reference waveforms and a plurality of sample waveforms obtained by irradiating a plurality of irradiation positions with terahertz waves is calculated. Standard deviation ratio = Standard deviation of sample waveform amplitude / Standard deviation of reference waveform amplitude and may be used as one of a plurality of parameters.

[0025] Another aspect of the present invention is a performance diagnostic device for diagnosing the performance of a lubricant used in equipment, comprising: a lubricant housing containing lubricant; an irradiation device that irradiates the lubricating oil in the lubricating oil casing with terahertz waves; a detection device that detects a transmitted wave that is irradiated from the irradiation device and passes through the lubricant oil or a reflected wave that is reflected from the lubricant oil to acquire data; an analysis control device that calculates a plurality of parameters including information about various characteristics related to the performance of the lubricating oil based on the acquired data; Equipped with This is a lubricant performance diagnostic device that uses multiple calculated measurement parameters to separate and identify various lubricant characteristics.

[0026] The lubricant performance diagnostic device as described above may further include a displacement device that changes the relative positions of the irradiation device and the detection device with respect to the lubricant housing.

[0027] The lubricant performance diagnostic device as described above may further include a reference waveform acquisition housing made of the same material and structure as the lubricant housing, and the transmitted waveform obtained by irradiating terahertz waves onto the reference waveform acquisition housing when there is no lubricant or when the lubricant is not deteriorated may be used as a reference waveform representing a standard reference state, and the transmitted waveform obtained by irradiating terahertz waves onto the lubricant to be measured in the lubricant housing may be used as a sample waveform.

[0028] In the lubricant performance diagnostic device as described above, a reference waveform may be acquired each time a sample waveform is acquired.

[0029] The lubricant performance diagnostic device as described above may further include a data transmission device for transmitting the data calculated by the analysis control device, and may be made online so that performance diagnosis can be performed at a remote location. [Effects of the Invention]

[0030] According to the present invention, it is possible to simultaneously quantitatively evaluate the degree of oxidation of lubricating oil, the amount of additive consumption, and the amount of water and wear particles mixed in. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a lubricant performance diagnostic device that utilizes terahertz time-domain spectroscopy. [Figure 2] 1A is a graph showing an example of a terahertz pulse wave, and FIG. 1B is a graph showing an example of a frequency spectrum, for illustrating an overview of terahertz pulse wave measurement. [Figure 3A] FIG. 1A is a schematic diagram showing an example of the configuration of a lubricant performance diagnostic device, and FIG. 1B is an enlarged view of a portion of the device where irradiation and detection are performed. [Figure 3B] (a) A schematic diagram showing an example of the configuration of a lubricant performance diagnosis device when correcting time fluctuations in device output, and (b) an enlarged view of the part of the device where irradiation and detection are performed. [Figure 3C]An example of the configuration of a lubricating oil performance diagnostic device is shown, along with an explanation of how it is possible to detect chemical and physical deterioration simultaneously. (a) A schematic diagram showing an example of the configuration of a lubricating oil performance diagnostic device, and (b) An enlarged view of the part of the device where irradiation and detection are performed. [Figure 3D] 1 is a diagram showing an example of the configuration of a lubricant performance diagnostic device in which a bypass pipe is installed. FIG. [Figure 3E] FIG. 10 is a diagram showing a configuration example in which a resin window is provided in a part of a lubricating oil pipe. [Figure 3F] 1 is a diagram illustrating an example of the configuration of a terahertz wave generator, sample oil, and detector in a lubricant performance diagnostic device. [Figure 4] 1 is a chart showing a measurement flow when diagnosing the performance of a lubricating oil, together with examples of waveforms acquired during the measurement flow. [Figure 5] 10 is a chart showing a measurement flow when diagnosing the performance of a lubricating oil while correcting time fluctuations in the output of the device. [Figure 6] 10 is a graph illustrating a reference waveform and a sample waveform. [Figure 7] 7 is a graph showing a frequency waveform obtained by Fourier transforming the waveform shown in FIG. 6. [Figure 8] 1 is a graph showing an image of a calibration curve. [Figure 9] FIG. 1 shows (A) an example of a lifespan estimation graph, (B) an example of a lifespan estimation graph obtained by calculating a regression equation based on data from two or more points, and (C) an example of a graph showing the remaining lifespan calculated from the regression equation and the remaining lifespan calculated from the speeds of the two most recent points. [Figure 10] 10 is a flowchart illustrating an example of a processing procedure when performing online diagnosis. [Figure 11] 1 is a graph showing the relationship between the degree of deterioration of a lubricating oil and measured values, obtained by a basic test using terahertz waves. [Figure 12] 10 is a graph showing the results of frequency analysis obtained from a basic test using terahertz waves. [Figure 13]1 is a graph showing the relationship between the viscosity of a lubricating oil and a measured value, obtained by a basic test using terahertz waves. [Figure 14] This figure explains an example of a procedure that allows output fluctuations to be corrected based on data measured each time when no sample is sandwiched between the irradiation device and the detection device, without the need to prepare an empty housing. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, preferred embodiments of a lubricant performance diagnostic technique using terahertz waves (a lubricant performance diagnostic method and device) according to the present invention will be described in detail with reference to the drawings (see FIG. 1, etc.).

[0033] [Terahertz time-domain spectroscopy] Terahertz time-domain spectroscopy is a method of directly measuring the time waveform of the transmitted or reflected wave when a terahertz pulse wave is irradiated onto an object, and then performing a Fourier transform to obtain information on the amplitude and phase for each frequency.

[0034] First, we will explain the configuration of a typical performance diagnostic device 1 for performing terahertz time-domain spectroscopy (see Figure 1). A light pulse emitted from a femtosecond laser 31 is split into pump light P1 and probe light P2 by a beam splitter 32. The pump light P1 is directed to a terahertz wave generator 33, and the probe light P2 is directed to a terahertz wave detector 43. The terahertz wave generator 33 and terahertz wave detector 43 emit or detect terahertz waves at the timing of the incident light pulse. The terahertz wave generator 33 and terahertz wave detector 43 typically use a photoconductive antenna (denoted by reference numeral 34 in Figure 3F). A movable mirror 42 is installed on the optical path of the probe light, and by operating this mirror, the time at which the probe light reaches the detector can be changed.

[0035] Next, we will explain the outline of terahertz pulse wave measurement (see Figure 2). A femtosecond laser emits pulse waves at a repetition rate of several tens of MHz, and the terahertz pulse waves emitted from the terahertz wave generator are also emitted at a similar repetition rate. Terahertz time-domain spectroscopy takes advantage of the fact that terahertz pulse waves are emitted at a constant period. That is, the difference in arrival time between the pump light and the probe light at the detection element is changed using a movable mirror, and the repeatedly arriving terahertz pulse waves are sampled, and the sampled data is finally combined to obtain the waveform of the terahertz pulse wave.

[0036] [Device configuration] The configuration of a performance diagnostic device 1 for lubricating oil L will be described with reference to a preferred example (see FIGS. 3A to 3F). The performance diagnostic device 1 is a device for diagnosing the degree of deterioration in the performance of lubricating oil L used in rotating equipment. The performance diagnostic device 1 of this embodiment includes a lubricating oil piping 10, an irradiation device 30, a detection device 40, an analysis control device 50, and the like (see FIG. 3A). The performance diagnostic device 1 may further include a reference waveform acquisition piping (reference waveform acquisition housing) 20, an automatic stage (displacement device) 60, a data transmission device 70, and the like (see FIGS. 3B and 3C). The rotating equipment is not particularly limited to any particular type.

[0037] The lubricant pipe 10 is a pipe for circulating the lubricant L used in the rotating device 100, and an irradiation device 30 and the like are installed along the way (see FIG. 3A, etc.). Here, a pipe for automatically circulating the lubricant L is used, but this is merely one suitable example of a housing containing the lubricant L, which is the diagnostic target (sample). A bypass pipe 10b with a different diameter may be newly installed to optimize the thickness of the lubricant depending on the transmittance of terahertz waves (see FIG. 3D). Furthermore, the bypass pipe may be installed vertically to prevent the deposition of foreign matter such as metal wear powder inside the bypass pipe. An example of the material or composition of the lubricant pipe 10 or the container 80 is a resin (such as polyethylene, polytetrafluoroethylene, or polystyrene) that can contain the lubricant L without any problems and has high transmittance to terahertz waves. Alternatively, only the portion of the lubricating oil pipe 10 or the container 80 through which the terahertz waves pass may be made of resin, for example, by providing a resin window in a metal container 80 (see FIG. 3E, in which the resin window is indicated by the symbol 10w). The shape of the lubricating oil pipe 10 or the container 80 is not particularly limited as long as it is a shape that can hold the lubricating oil L, such as a rectangle or a cylinder, but since the output of the transmitted wave decreases in proportion to the wall thickness, a thin and uniform wall thickness is desirable.

[0038] The irradiation device 30 is provided as a device for irradiating the lubricating oil L in the lubricating oil pipe 10 (or container 80) with terahertz waves (see FIG. 3A, etc.). A specific example of the irradiation device 30 is a device using a femtosecond laser 31 and a terahertz wave generating element 33 in the general performance diagnostic device 1 described above.

[0039] The detection device 40 is provided as a device that detects a transmitted waveform irradiated from the irradiation device 30 and transmitted through the lubricating oil L or a reflected waveform reflected from the lubricating oil L to acquire data (see FIG. 3A, etc.). The detection device 40 and the above-mentioned irradiation device 30 are arranged so that the lubricating oil pipe 10 (or container 80) containing the lubricating oil L is located between them. As a specific example, in this embodiment, the irradiation device 30 is arranged on the upper side and the detection device 40 is arranged on the lower side so as to sandwich the lubricating oil pipe 10 therebetween (see FIG. 3A, etc.). Alternatively, the irradiation device 30 and the detection device 40 may be arranged on the side of the container 80 containing the lubricating oil L so as to sandwich the container 80 therebetween (see FIG. 3F).

[0040] The analysis control device 50 is configured as, for example, a computer and installed as a device (measuring device) constituting an analysis control unit that calculates, based on the acquired data, multiple parameters including information on various characteristics related to the performance of the lubricating oil L (see FIG. 3A, etc.). Parameters including information on various characteristics include, for example, the viscosity of the lubricating oil L, the degree of oxidation, the amount of additive consumption, the amount of water, and the amount of metal wear particles. The performance diagnosis device 1 of this embodiment separates and identifies at least two of these parameters and diagnoses the degree of deterioration of the lubricating oil L, as will be described later.

[0041] The reference waveform acquisition pipe 20 is used to correct output fluctuations over time when repeated measurements are performed (see Figure 3B). The reference waveform acquisition pipe 20 is formed of the same material and structure as the lubricant pipe 10. The reference waveform represents the reference state, and the transmitted waveform obtained by irradiating the reference waveform acquisition pipe 20 with terahertz waves when there is no lubricant L or when the lubricant L is not degraded. The transmitted waveform obtained by irradiating the lubricant L to be measured in the lubricant pipe 10 with terahertz waves is used as the sample waveform. Output fluctuations can be corrected by using both waveforms. This is because, depending on the instrument used, the terahertz wave output may be unstable and may fluctuate over time, resulting in reduced degradation detection accuracy. As described above, the reference waveform acquisition pipe 20, made of the same material and dimensions as the lubricant pipe 10 used for sample measurement, is prepared next to the lubricant pipe 10. By acquiring a reference waveform each time a sample is measured, the effects of time fluctuations can be corrected. When a container 80 is used instead of the lubricating oil pipe 10, a container 80 made of the same material and structure as the container 80 can be used as the reference waveform acquisition housing.

[0042] The automatic stage (displacement device) 60 is provided as a device for changing the relative positions of the irradiation device 30 and the detection device 40 with respect to the lubricant oil pipe 10 (see FIG. 3B). The automatic stage 60 of this embodiment is composed of a linear guide, a motor, a drive force transmission mechanism (gears and belts), an automatic control device, etc. for moving at least a portion of the irradiation device 30 that irradiates terahertz waves and a portion of the irradiation device 40 that detects at least a transmitted waveform that has passed through the lubricant oil L or a reflected waveform that has been reflected from the lubricant oil L, in a direction across the lubricant oil pipe 10. When the reference waveform acquisition pipe 20 is installed near the lubricant oil pipe 10, the automatic stage 60 may be configured so that the irradiation device 30 (at least the portion that irradiates terahertz waves) etc. reciprocates between the lubricant oil pipe 10 and the reference waveform acquisition pipe 20 (see FIG. 3B). If the irradiation device 30 and the detection device 40 are disposed to the side of the container 80, the automatic stage 60 may be configured to move the container 80 vertically or in a direction crossing the terahertz waves (see FIG. 3F). The automatic stage 60 is preferably configured to be movable at a measurement pitch width according to the required measurement form, for example, at a measurement pitch width of about 1 mm. Note that instead of moving the irradiation device 30 (at least the portion that irradiates the terahertz waves), the lubricating oil pipe 10 or the reference waveform acquisition pipe 20 (or the container 80) may be moved.

[0043] The data transmission device 70 is a device that transmits data calculated by the analysis control device 50 (see FIG. 3C). A performance diagnosis device 1 further including the data transmission device 70 can realize an online device that can perform performance diagnosis at a remote location.

[0044] [Measurement and diagnostic methods] In this embodiment, the performance diagnosis device 1 configured as described above uses the irradiation device 30 to irradiate the lubricating oil L with terahertz waves, and the detection device 40 acquires transmitted waves that have passed through the lubricating oil L or reflected waves that have been reflected from the lubricating oil L. Based on the acquired data, multiple parameters are calculated, and the calculated multiple parameters are used to separate and identify at least two of the viscosity, oxidation level, additive consumption amount, water content, and amount of metal wear particles of the lubricating oil L, thereby diagnosing the performance of the lubricating oil L. The details of such measurements and diagnosis are described below. The following also describes the case where a container 80 is used, but it goes without saying that measurements and diagnosis can also be performed using the lubricating oil piping 10 or the reference waveform acquisition piping 20 instead.

[0045] The lubricating oil L to be measured may be in a static or flowing state. However, if the lubricating oil L is in a static state, foreign matter or moisture contained in the oil may settle to the bottom of the container 80, so it is desirable to measure the oil in a short time after thoroughly stirring it.

[0046] (1) Obtaining the reference waveform Before measuring the sample lubricating oil L, terahertz waves are irradiated onto an empty container 80 (or the reference waveform acquisition pipe 20) to acquire a transmitted waveform (referred to as the "reference waveform") (step SP1). The measurement may be repeated multiple times and an average taken. If the container 80 (or the reference waveform acquisition pipe 20) is empty and measurement is not possible, the transmitted waveform of a new oil or an oil immediately after the start of measurement may be used as the reference waveform (see FIG. 4).

[0047] (2) Acquiring sample waveforms Terahertz waves are irradiated onto a container 80 (or lubricant pipe 10) containing a sample (lubricant L), and a transmitted waveform (referred to as the "sample waveform") is acquired (step SP2). This process is repeated until a predetermined number of times is reached. In the case of a container 80 with a uniform irradiated surface (i.e., the thickness or material of the container 80 does not vary from place to place), measurements may be repeated while changing the position of the irradiation device 30, the detection device 40, or the measurement target using an automatic stage 60, for example, by shifting the position at 1 mm intervals to acquire several hundred data points. Generally, foreign matter such as wear particles and moisture is not uniformly dispersed in oil, resulting in uneven concentration (see FIG. 3C). In this embodiment, this uneven concentration is evaluated based on the variation (standard deviation) in the amplitude of the transmitted waveform. However, in the case of stationary lubricant L, the concentration distribution in the oil does not change (the concentration at a given measurement point does not change during measurement), making it difficult to evaluate using fixed-point measurement. For this reason, it is desirable to repeat measurements while changing the position as described above for stationary lubricant L. On the other hand, in the case of the lubricating oil L flowing inside the lubricating oil pipe 10, the concentration distribution constantly changes as it flows, so that it may be possible to evaluate it even by fixed point measurement.

[0048] (3) Parameter calculation Based on the measurement data (reference waveform and sample waveform) acquired in (2) above, parameters are calculated (step SP3). An example of the parameters is shown below.

[0049] a) Transmittance Reference waveform amplitude A R and the amplitude A of the sample waveform S The transmittance is calculated by taking the ratio of the values ​​of the reference state (air or new lubricating oil L). The statistics of each measurement point (average, maximum, minimum, etc.) may also be used as parameters. Transmittance = Amplitude A of sample waveform S / Reference waveform amplitude A R

[0050] b) Peak time difference (refractive index) The time it takes for terahertz waves to pass through a material and reach the detection device increases as the refractive index of the material increases. Therefore, the time it takes for light passing through the sample (deteriorated lubricating oil L) to reach the detection device 40 is slower than the time it takes for light passing through the reference state (air or new oil) to reach the detection device 40, due to the increase in the refractive index (see Figure 6). From this perspective, by taking the difference in the appearance times of the peak values ​​of the reference waveform and the sample waveform (peak time difference), the time difference corresponding to the increase in the refractive index can be calculated and used as a parameter. Peak time difference = Peak time t of sample waveform S - Peak time t of the reference waveform R The optical path length and the speed of light may be converted into a refractive index, which may then be used as a parameter. Refractive index = Peak time difference·Speed ​​of light / Optical path length Furthermore, statistics (average value, maximum value, minimum value, etc.) of each measurement point may be used as a parameter.

[0051] c) Transmittance and refractive index at specific frequencies The reference waveform and sample waveform are each Fourier transformed to obtain amplitude and phase information for each frequency. Based on this, the transmittance and refractive index for each frequency are calculated, and the value at a specific frequency or the average value for a specific interval is used as a parameter. Statistics for each measurement point (average, maximum, minimum, etc.) can also be used as a parameter.

[0052] d) Ratio of standard deviations Amplitude A of the reference waveform when measuring multiple points R and the amplitude A of the sample waveform S The standard deviation of these is calculated, and the ratio of these is taken as the parameter. Standard deviation ratio = sample waveform amplitude A S Standard deviation of / amplitude A of reference waveform R Standard deviation of

[0053] [Measurement and diagnostic methods for correcting terahertz wave output fluctuations] If the output of the terahertz waves fluctuates over time due to circumstances on the irradiation device 30 side, the measurement accuracy may decrease due to the difference in output between when the reference waveform and when the sample waveform are acquired. In this case, in order to improve measurement accuracy, two identical containers (or pipes) may be prepared, one for acquiring the reference waveform and the other for acquiring the sample waveform, and the reference waveform may be acquired each time a sample is measured. The procedure for this case is shown below (see Figure 5).

[0054] (1) Acquisition of vessel calibration data Although the reference waveform acquisition container 80 (or reference waveform acquisition pipe 20) and the sample measurement container 80 (or lubricant oil pipe 10) are the same, it is possible that the transmission characteristics differ between the containers (or pipes) due to minute manufacturing dimensional differences, variations in material components, and the like. To calibrate the difference in terahertz wave transmission characteristics between the containers (or pipes) (described below), terahertz waves may be irradiated onto an empty container 80 (or pipe) as needed, and the respective transmission waveforms (referred to as the "transmission waveform of the reference waveform acquisition container" and the "transmission waveform of the sample measurement container," respectively) may be obtained (step SP11). Alternatively, the measurement may be repeated multiple times and the average of each may be calculated.

[0055] (2) Obtaining the reference waveform, (3) Obtaining the sample waveform In actual measurements, first, terahertz waves are irradiated onto a container 1 (designated 80R in FIG. 5) for acquiring a reference waveform, and a reference waveform is acquired (step SP12). Then, the irradiation device 30 and the detection device 40, or the measurement object (container or piping), are moved using the automatic stage 60, and the lubricating oil L sample in the sample measurement container 2 (designated 80S in FIG. 5) is irradiated with terahertz waves, and a sample waveform is acquired (step SP13). This operation is repeated until a predetermined number of times is reached. Note that, in the case of a container 80 (80R, 80S) with a uniform irradiation surface (i.e., the thickness or material of the container 80 does not vary depending on the location), the irradiation device 30 and the detection device 40, or the measurement object, may be moved using the automatic stage 60, and measurements may be repeated while changing positions, for example, by shifting the position at 1 mm intervals to acquire several hundred points of data.

[0056] (4) Calibration of differences between containers If necessary, the difference in terahertz wave transmission characteristics between the containers is calibrated (step SP14) based on the data of the transmitted wave waveform of the reference waveform acquisition container 80R and the transmitted wave waveform of the sample measurement container 80S measured in advance (see Figure 5).

[0057] (5) Calculation of parameters Based on the acquired data, the above-mentioned parameters (transmittance, refractive index, standard deviation ratio, etc.) are calculated (step SP15). At this time, the reference waveform used is the one acquired each time before sample measurement.

[0058] [Deterioration judgment] The relationship between the degree of deterioration of the oil type being measured (lubricating oil L) and the aforementioned parameters a) to d) is measured in advance, and a calibration curve is created. Here, the type and degree of deterioration of the sample is determined based on the measured parameters and the calibration curve. For example, if the parameter is "transmittance," the measured value of transmittance is applied to this calibration curve, and the degree of deterioration that corresponds one-to-one to the measured value is identified (see Figure 8). As a simple method, an allowable value for the rate of change from the initial state for each parameter can be set, and the presence or absence of an abnormality can be determined based on this (for example, a 20% change in transmittance from the initial value can be determined to be an abnormality).

[0059] [Remaining life estimation] For each type of deterioration (oxidation, additive consumption, water contamination, metal wear powder contamination), the rate of deterioration is calculated from the current level of deterioration and the period of use (see Figure 9(A)). Deterioration rate = Deterioration level at time of measurement / Duration of use

[0060] If there are data for two or more points, it is possible to estimate the change in deterioration over time by calculating a regression equation based on the data, assuming that the relationship between time and the degree of deterioration may be expressed in a nonlinear form such as an exponential function (see Figure 9(B)). For example, it is possible to obtain data at multiple times, such as one year, two years, three years after the start of use, calculate a regression equation, and then extrapolate the resulting regression equation to estimate the degree of deterioration in the future. Alternatively, the rate of deterioration can be calculated using data from the most recent two points (see Figure 9(C)).

[0061] Based on the rate of deterioration or the change in deterioration over time obtained above, the time until a predetermined limit value is reached is calculated (see Figures 9(A), (B), etc.). The time until each limit value of deterioration is reached is compared, and the shortest time is adopted as the remaining life of lubricant L.

[0062] [Online equipment diagnosis method] An example of a processing procedure for performing equipment diagnosis using the measurement and diagnosis method described above will be described with reference to the drawings (see FIG. 10).

[0063] When the operation of a factory machine or equipment (or various operating devices therein) is started (step SP21), the transmitted waveform irradiated by the irradiation device 30 and transmitted through the lubricant L or the reflected waveform reflected from the lubricant L is detected by the detection device 40 to acquire data (step SP22). Subsequently, the parameters are calculated (step SP23) and the remaining life is estimated (step SP24), and a decision is made as to whether or not the operation of the equipment (or operating device) should be continued in light of the estimated remaining life obtained (step SP25). If it is determined that the operation should be continued (YES in step SP25), the process returns to step SP22, and the series of processes from data acquisition, parameter calculation, life estimation, and the decision to continue operation are repeated (steps SP22 to SP25). On the other hand, if it is determined that the operation should not be continued (NO in step SP25), the operation of the equipment (or operating device) is stopped (step SP26), and work such as oil change and inspection is performed (step SP27).

[0064] Of these processes, the measurement and diagnosis processes can be performed online at a remote location using the data transmission device 70. In this case, the deterioration state and remaining life of the lubricant L can be monitored to determine when to replace the lubricant L or when to inspect the equipment. Alternatively, this process can be performed in combination with conventional techniques such as precise lubricant diagnosis and equipment vibration diagnosis. In other words, the need for precise analysis of the lubricant L or vibration diagnosis of the equipment can be determined based on the results of the deterioration determination using the method of this embodiment (utilizing it as a primary screening technique for more detailed measurements).

[0065] The lubricating oil L performance diagnostic device 1 and performance diagnostic method using the device described above can simultaneously quantitatively evaluate various degradation patterns of the lubricating oil L, such as oxidation degradation, additive consumption, and contamination with water and wear particles, using a single device. Furthermore, in the lubricating oil L of actual machinery or its operating equipment, multiple degradation events, such as oxidation degradation, water contamination, and metal powder contamination, occur simultaneously. While conventional techniques that monitor a single monitoring item have difficulty identifying and quantitatively evaluating these events, the device or method of the present embodiment makes it possible to identify and quantitatively evaluate these events. Furthermore, when using visible light or near-infrared light, there is a concern that the transmittance of significantly deteriorated lubricating oil is low, resulting in reduced measurement accuracy. However, the device or method of the present embodiment eliminates such concerns. [Example]

[0066] [Example 1] A basic test using terahertz waves was conducted, and a graph was obtained showing the relationship between the amount of wear debris in the lubricant and the ratio of the standard deviation of the peak intensity (see Figure 11). It was confirmed that it is possible to separate and identify the amount of metal wear debris by evaluating the ratio of the standard deviation.

[0067] [Example 2] A basic test using terahertz waves was conducted, and the graph obtained as a result of frequency analysis is shown in Figure 12. From this, it was confirmed that it is possible to separate and detect moisture by evaluating the transmittance in the low frequency range (see Figure 12).

[0068] [Example 3] A basic test using terahertz waves was conducted, and the graph obtained by comparing oils of different viscosities is shown in Figure 13. From this, a large difference in peak time difference was observed (the higher the viscosity, the higher the refractive index), confirming the possibility of using this method to check the viscosity of the oil type used in equipment (whether an oil type with an appropriate viscosity is being used).

[0069] The above-described embodiment is one example of a preferred embodiment of the present invention, but is not limited to this, and various modifications can be made within the scope of the present invention. For example, in the above-described embodiment, the reference waveform is acquired using a housing such as an empty container 80 (or a reference waveform acquisition pipe 20), but even if such an empty housing is not prepared, it is possible to correct output fluctuations based on data measured each time when no sample is sandwiched between the irradiation device 30 and the detection device 40. That is, as an example (see FIG. 14), (1) Data is measured when there is nothing between the irradiation device 30 and the detection device 40, and correction data is obtained (step SP31). (2) Immediately before or after the acquisition of the sample waveform, a waveform in a reference state (empty state or state containing new oil) is acquired (step SP32). (3) Data is measured when there is nothing between the irradiation device 30 and the detection device 40, and correction data is obtained (step SP33). (4) Sample data of the sample (deteriorated lubricant oil) is obtained from the transmitted waveform of the housing containing oil (step SP34). Here, steps SP33 and SP34 are repeated a predetermined number of times (see FIG. 14). (5) The sample data is corrected by correcting the output change over time based on the correction data (step SP35). (6) Calculate the parameters (step SP36). Measurement and diagnosis can be performed according to the above flow. When performing measurement and diagnosis according to this flow, steps (3) and (4) may be repeated to obtain multiple pieces of data. Furthermore, the state of (1) may be used as a reference to correct the output of each sample waveform, that is, the amount of correction may be determined by comparing the waveform without anything inserted obtained in (1) with the waveform without anything inserted obtained in (3). Furthermore, each parameter may be calculated based on the corrected sample waveform and the reference waveform obtained in (1). [Industrial Applicability]

[0070] The present invention is suitable for application to a performance diagnostic method and a performance diagnostic device for diagnosing the degree of deterioration in the performance of lubricating oil used in various operating devices in factory machinery and equipment. [Explanation of symbols]

[0071] 1...Performance diagnostic device 10...Lubricant piping (lubricant housing) 10b...Bypass piping 10w...plastic window 20...Pipe for acquiring reference waveform (enclosure for acquiring reference waveform) 30…Irradiation device 31...Femtosecond laser 32...Beam splitter 33...Terahertz wave generating element 34...Photoconductive antenna 40...Detection device 42... Movable mirror 43...Terahertz wave detection element 50...Analysis control device 60...Automatic stage (displacement device) 70...Data transmission device 80...Container (lubricant container, reference waveform acquisition container) 80R…Reference waveform acquisition container 80S: Container for acquiring sample waveforms 100...Rotating equipment AR …Reference waveform amplitude A S ...amplitude of sample waveform L…Lubricating oil P1: Pump light P2: Probe light

Claims

1. A performance diagnostic method for diagnosing the performance of a lubricating oil, comprising: irradiating the lubricating oil with terahertz waves using an irradiation device; acquiring a transmitted wave that has passed through the lubricating oil or a reflected wave that has been reflected from the lubricating oil using a detection device; calculating a plurality of parameters based on the acquired data; and determining the calculated plurality of parameters as follows: Transmittance (where transmittance is a parameter obtained by dividing the amplitude of the sample waveform by the amplitude of the reference waveform, and the reference waveform represents a reference state based on the transmitted waveform or reflected waveform obtained by irradiating the terahertz wave in a state where the lubricant is absent or where the lubricant is not deteriorated) ・Peak time difference (where peak time difference = peak time of sample waveform - peak time of reference waveform) - Refractive index (where refractive index = peak time difference * speed of light / optical path length) - Values ​​at a specific frequency or average values ​​in a specific section obtained by performing a Fourier transform on the reference waveform and the sample waveform, respectively, to obtain amplitude and phase information for each frequency, and calculating the transmittance and refractive index for each frequency based on this information A ratio of the standard deviations of the amplitudes of the plurality of reference waveforms and the plurality of sample waveforms obtained by irradiating the terahertz waves at a plurality of irradiation positions (standard deviation ratio = standard deviation of the amplitudes of the sample waveforms / standard deviation of the amplitudes of the reference waveforms) and separately identifying at least two of the viscosity, oxidation level, additive consumption, water content, and metal wear powder content of the lubricating oil by using any one of the above.

2. A performance diagnostic method for diagnosing the performance of a lubricating oil, comprising: irradiating terahertz waves onto the lubricating oil using an irradiation device; acquiring transmitted waves that have passed through the lubricating oil or reflected waves that have been reflected from the lubricating oil using a detection device; calculating a plurality of parameters based on the acquired data; using the calculated plurality of parameters to separate and identify at least two of the viscosity of the lubricating oil, the degree of oxidation, the amount of additive consumption, the water content, and the amount of metal wear powder; using as the parameters a reference waveform that represents a reference state as a reference, the transmitted waveform or reflected waveform obtained by irradiating terahertz waves in a state where the lubricating oil is not present; and a sample waveform that is obtained by irradiating terahertz waves onto the lubricating oil to be measured; and using a waveform calculated from both the reference waveform and the sample waveform.

3. A performance diagnostic method for diagnosing the performance of a lubricating oil, comprising: irradiating the lubricating oil with terahertz waves using an irradiation device; acquiring the transmitted waves that have passed through the lubricating oil or the reflected waves that have been reflected from the lubricating oil using a detection device; calculating a plurality of parameters based on the acquired data; and using the calculated plurality of parameters, separating and identifying at least two of the viscosity, degree of oxidation, additive consumption, water content, and amount of metal wear powder of the lubricating oil; As the parameter, a transmission waveform or a reflection waveform obtained by irradiating the terahertz wave in a state where the lubricating oil is not present or where the lubricating oil is not deteriorated is used as a reference waveform representing a reference state, and a transmission waveform or a reflection waveform obtained by irradiating the terahertz wave to the lubricating oil to be measured is used as a sample waveform, and a value calculated from both the reference waveform and the sample waveform is used, A lubricating oil performance diagnosis method in which a correction waveform is obtained in addition to the sample waveform, and output fluctuations are corrected based on the correction waveform.

4. The lubricating oil performance diagnosis method according to any one of claims 1 to 3, wherein the irradiation of the terahertz waves and the acquisition of the data are repeated, and the acquired data or a plurality of parameter statistics calculated based on the acquired data are used as the parameters.

5. The method for diagnosing lubricant performance according to claim 4, wherein the data is repeatedly acquired while changing the position where the terahertz waves are irradiated.

6. A performance diagnostic method for diagnosing the performance of a lubricating oil, comprising: using an irradiation device to irradiate terahertz waves onto the lubricating oil; acquiring transmitted waves that have passed through the lubricating oil or reflected waves that have been reflected from the lubricating oil using a detection device; calculating a plurality of parameters based on the acquired data; using the calculated plurality of parameters to separate and identify at least two of the viscosity of the lubricating oil, the degree of oxidation, the amount of additive consumption, the water content, and the amount of metal wear powder; defining a calibration curve for each type of lubricating oil to be measured based on data obtained by previously measuring the relationship between various characteristics related to the performance of the lubricating oil and the parameters; and using the calibration curve as the basis for performance diagnosis.

7. 7. A lubricant performance diagnosis method according to claim 3, wherein an allowable value for the rate of change from the initial state of the lubricant for the parameter is set, and the presence or absence of an abnormality in the lubricant is determined based on the allowable value.

8. For each index indicating the characteristics related to the performance of the lubricating oil, the rate of deterioration is calculated based on the degree of deterioration of the lubricating oil at the time of detection and the period of use. Deterioration rate at the time of detection = Degree of deterioration at the time of measurement / Duration of use The method for diagnosing lubricating oil performance according to any one of claims 1 to 7, wherein the lubricating oil performance is calculated based on the following formula:

9. 9. The method for diagnosing lubricant performance according to claim 8, wherein the remaining life of the lubricant is calculated as the time until the rate of deterioration or the change in deterioration over time reaches a predetermined limit value.

10. 10. A lubricant performance diagnosis method according to claim 9, wherein the shortest time among the times until the respective deterioration rates calculated for the respective indicators reach the respective limit values ​​is calculated as the remaining life of the lubricant.

11. The lubricant performance diagnostic method according to claim 1 , wherein the data is acquired by terahertz time-domain spectroscopy, and the plurality of parameters are calculated based on the acquired data.

12. A performance diagnostic method for diagnosing the performance of a lubricating oil, comprising: irradiating the lubricating oil with terahertz waves using an irradiation device; acquiring the transmitted waves that have passed through the lubricating oil or the reflected waves that have been reflected from the lubricating oil using a detection device; calculating a plurality of parameters based on the acquired data; and using the calculated plurality of parameters, separating and identifying at least two of the viscosity, degree of oxidation, additive consumption, water content, and amount of metal wear powder of the lubricating oil; As the parameter, a transmission waveform or a reflection waveform obtained by irradiating the terahertz wave in a state where the lubricating oil is not present or where the lubricating oil is not deteriorated is used as a reference waveform representing a reference state, and a transmission waveform or a reflection waveform obtained by irradiating the terahertz wave to the lubricating oil to be measured is used as a sample waveform, and a value calculated from both the reference waveform and the sample waveform is used, By taking the ratio of the amplitudes of the reference waveform and the sample waveform, the transmittance based on the reference state can be calculated. Transmittance = sample waveform amplitude / reference waveform amplitude and setting the calculated value as one of the plurality of parameters.

13. A performance diagnostic method for diagnosing the performance of a lubricating oil, comprising: irradiating the lubricating oil with terahertz waves using an irradiation device; acquiring the transmitted waves that have passed through the lubricating oil or the reflected waves that have been reflected from the lubricating oil using a detection device; calculating a plurality of parameters based on the acquired data; and using the calculated plurality of parameters, separating and identifying at least two of the viscosity, degree of oxidation, additive consumption, water content, and amount of metal wear powder of the lubricating oil; As the parameter, a transmission waveform or a reflection waveform obtained by irradiating the terahertz wave in a state where the lubricating oil is not present or where the lubricating oil is not deteriorated is used as a reference waveform representing a reference state, and a transmission waveform or a reflection waveform obtained by irradiating the terahertz wave to the lubricating oil to be measured is used as a sample waveform, and a value calculated from both the reference waveform and the sample waveform is used, By taking the difference in the appearance time of the peak values ​​of the reference waveform and the sample waveform, the peak time difference when the reference state is used as a reference is calculated. Peak time difference = Peak time of sample waveform - Peak time of reference waveform and setting the calculated value as one of the plurality of parameters.

14. From the optical path length and the speed of light of the irradiated terahertz wave, Refractive index = Peak time difference x Speed ​​of light / Optical path length 14. The lubricating oil performance diagnosis method according to claim 13, wherein the refractive index is converted into a refractive index by the following formula:

15. A performance diagnostic method for diagnosing the performance of a lubricating oil, comprising: irradiating the lubricating oil with terahertz waves using an irradiation device; acquiring transmitted waves that have passed through the lubricating oil or reflected waves that have been reflected from the lubricating oil using a detection device; calculating a plurality of parameters based on the acquired data; and using the calculated plurality of parameters, separating and identifying at least two of the viscosity, degree of oxidation, additive consumption amount, water content, and amount of metal wear powder of the lubricating oil; As the parameter, a transmission waveform or a reflection waveform obtained by irradiating the terahertz wave in a state where the lubricating oil is not present or where the lubricating oil is not deteriorated is used as a reference waveform representing a reference state, and a transmission waveform or a reflection waveform obtained by irradiating the terahertz wave to the lubricating oil to be measured is used as a sample waveform, and a value calculated from both the reference waveform and the sample waveform is used, A lubricating oil performance diagnosis method, which performs a Fourier transform on the reference waveform and the sample waveform, respectively, to obtain amplitude and phase information for each frequency, calculates the transmittance and refractive index for each frequency based on this information, and sets the value at a specific frequency or the average value for a specific section as one of the multiple parameters.

16. A performance diagnostic method for diagnosing the performance of a lubricating oil, comprising: irradiating the lubricating oil with terahertz waves using an irradiation device; acquiring transmitted waves that have passed through the lubricating oil or reflected waves that have been reflected from the lubricating oil using a detection device; calculating a plurality of parameters based on the acquired data; and using the calculated plurality of parameters, separating and identifying at least two of the viscosity, degree of oxidation, amount of additives consumed, amount of water, and amount of metal wear powder of the lubricating oil; As the parameter, a transmission waveform or a reflection waveform obtained by irradiating the terahertz wave in a state where the lubricating oil is not present or where the lubricating oil is not deteriorated is used as a reference waveform representing a reference state, and a transmission waveform or a reflection waveform obtained by irradiating the terahertz wave to the lubricating oil to be measured is used as a sample waveform, and a value calculated from both the reference waveform and the sample waveform is used, The ratio of the standard deviations of the amplitudes of the plurality of reference waveforms and the plurality of sample waveforms obtained by irradiating the terahertz waves at a plurality of irradiation positions is calculated. Standard deviation ratio = Standard deviation of sample waveform amplitude / Standard deviation of reference waveform amplitude and setting the calculated value as one of the plurality of parameters.

17. A performance diagnostic device for diagnosing the performance of a lubricating oil used in equipment, a lubricant housing containing the lubricant; an irradiation device that irradiates the lubricant in the lubricant casing with terahertz waves; a detection device that detects a transmitted wave that is irradiated from the irradiation device and passes through the lubricating oil or a reflected wave that is reflected from the lubricating oil to acquire data; an analysis control device that calculates a plurality of parameters including information about various characteristics related to the performance of the lubricating oil based on the acquired data; Equipped with Using the calculated plurality of measurement parameters, at least two of the viscosity, oxidation level, additive consumption amount, water content, and metal wear powder amount of the lubricating oil are separated and identified; The lubricant performance diagnostic device further includes a reference waveform acquisition housing made of the same material and structure as the lubricant housing, and uses a transmission waveform obtained by irradiating terahertz waves onto the reference waveform acquisition housing when there is no lubricant or when the lubricant is not deteriorated as a reference waveform representing a standard reference state, and uses a transmission waveform obtained by irradiating terahertz waves onto the lubricant to be measured in the lubricant housing as a sample waveform.

18. The lubricant performance diagnostic device according to claim 17, further comprising a displacement device that changes the relative positions of the irradiation device and the detection device with respect to the lubricant housing.

19. The lubricant performance diagnostic device according to claim 17, wherein the reference waveform is acquired each time the sample waveform is acquired.

20. 20. The lubricating oil performance diagnostic device according to claim 17, further comprising a data transmission device that transmits data calculated by the analysis control device, and is online so as to enable performance diagnosis at a remote location.

Images