Measurement method, measurement device, and program

Abstract

In the measuring method for measuring the state of a device for lubricating parts by means of a lubricant, an AC voltage is applied to a circuit comprising parts lubricated by the lubricant, the impedance and phase angle of the circuit when the AC voltage is applied are measured, and the state of the device is measured on the basis of the impedance and the phase angle. And deriving an oil film thickness and a metal contact ratio between the components, the oil film thickness and the metal contact ratio between the components being derived using a probability density function of the surface roughness between the components in a contact region between the components, using a calculation formula defining a capacitance of the contact region.

Description

Technical Field

[0001] The present invention relates to a measuring method, a measuring device and a program. Background Art

[0002] In the past, in rolling devices such as bearing devices, structures that use lubricants (e.g., lubricating oil, grease) to lubricate their rotation have become widely popular. On the other hand, for rotating parts such as bearing devices, damage and wear are detected as early as possible by regularly performing status diagnosis to suppress the occurrence of failures of rotating parts.

[0003] In a rolling device using a lubricant, in order to diagnose its operating state, it is required to appropriately detect the internal state. For example, Patent Document 1 discloses the following method: In a rolling device, it is assumed that the electrostatic capacitance of the oil film of a contact surface with surface roughness is equal to the electrostatic capacitance of a smooth surface, and the oil film thickness of the contact surface without metal contact is the average oil film thickness, thereby calculating the electrostatic capacitance of the contact surface.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-211317 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, the electrostatic capacitance is inversely proportional to the oil film thickness, so in reality the influence of the thin film portion becomes greater, and the electrostatic capacitance may be greater than the case where the average oil film thickness is assumed. In the method of Patent Document 1, since the average oil film thickness is used to calculate the electrostatic capacitance, the accuracy of the calculation result of the electrostatic capacitance is reduced when the oil film thickness of the contact surface deviates from the average oil film thickness. In particular, it is believed that the surface roughness of the contact surface will also affect the oil film thickness, resulting in a reduction in the accuracy of the calculation result of the electrostatic capacitance.

[0009] In view of the above problems, an object of the present invention is to provide a measuring method for detecting the oil film thickness in a device and the metal contact ratio between components with higher accuracy than conventional methods.

[0010] Means for solving problems

[0011] In order to solve the above-mentioned problems, the present invention has the following structure. That is, a measuring method characterized by measuring the state of a device that lubricates parts with a lubricant,

[0012] applying an AC voltage to a circuit consisting of components lubricated by the lubricant,

[0013] measuring the impedance and phase angle of the circuit when the AC voltage is applied,

[0014] deriving the oil film thickness and the metal contact ratio between the components based on the impedance and the phase angle,

[0015] The oil film thickness and the metal contact ratio between the components are derived using a calculation formula obtained by using the electrostatic capacitance that defines the contact area using a probability density function of the surface roughness between the components in the contact area between the components.

[0016] In addition, another embodiment of the present invention has the following structure. That is, a measuring device is characterized in that the measuring device measures the state of a device that lubricates parts using a lubricant, and has:

[0017] an acquisition unit that applies an AC voltage to a circuit formed by a component lubricated by the lubricant and acquires an impedance and a phase angle of the circuit when the AC voltage is applied; and

[0018] a deriving unit, wherein the deriving unit derives the oil film thickness and the metal contact ratio between the components based on the impedance and the phase angle,

[0019] The oil film thickness and the metal contact ratio between the components are derived using a calculation formula obtained by using the electrostatic capacitance that defines the contact area using a probability density function of the surface roughness between the components in the contact area between the components.

[0020] Another aspect of the present invention has the following structure. That is, a program characterized by causing a computer to function as an acquisition unit and a derivation unit,

[0021] The acquisition unit applies an AC voltage to a circuit formed by a component lubricated by the lubricant, and acquires an impedance and a phase angle of the circuit when the AC voltage is applied.

[0022] The deriving unit derives the oil film thickness and the metal contact ratio between the components based on the impedance and the phase angle,

[0023] The oil film thickness and the metal contact ratio between the components are derived using a calculation formula obtained by using the electrostatic capacitance that defines the contact area using a probability density function of the surface roughness between the components in the contact area between the components.

[0024] Effects of the Invention

[0025] According to the present invention, the oil film thickness in the device and the metal contact ratio between components can be detected with higher accuracy than conventional methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a diagram showing a physical model of the bearing device of the present invention.

[0027] Figure 2 This is a diagram showing a physical model of the bearing device of the present invention.

[0028] Figure 3 This is a circuit diagram for explaining an equivalent circuit around a contact region of the present invention.

[0029] Figure 4 This is a graph for explaining the analysis results of the conventional method.

[0030] Figure 5 This is a graph for explaining the analysis results of the conventional method.

[0031] Figure 6 This is a conceptual diagram for explaining the state of the contact area and its surroundings according to the present invention.

[0032] Figure 7 This is a conceptual diagram for explaining the contact distribution of the contact area of ​​the present invention.

[0033] Figure 8 This is a schematic diagram showing a configuration example of a device to which the diagnostic method according to one embodiment of the present invention can be applied.

[0034] Fig. 9 This is a flowchart of a process during diagnosis according to one embodiment of the present invention.

[0035] Fig.10 This is a graph for explaining the analysis results of the diagnostic method of the present invention.

[0036] Fig.11 This is a graph for explaining the analysis results of the diagnostic method of the present invention.

[0037] Fig.12 This is a graph for explaining the analysis results of the diagnostic method of the present invention. DETAILED DESCRIPTION

[0038] Hereinafter, the mode for implementing the present invention will be described with reference to the accompanying drawings and the like. In addition, the embodiment described below is used to illustrate one embodiment of the present invention and is not intended to limit the interpretation of the present invention. In addition, all structures described in each embodiment are not necessarily structures necessary to solve the problems of the present invention. In addition, in each of the drawings, the same constituent elements are indicated by marking the same reference numerals to indicate the corresponding relationship.

[0039] <First Embodiment>

[0040] The first embodiment of the present invention is described below. It should be noted that the measuring method of the present invention can be applied to a device in which a metal surface with a certain roughness is lubricated while rolling contact or sliding. Examples of such devices include rolling bearings, gears, sliding bearings, cams, traction transmissions, CVT (Continuously Variable Transmission), etc. Specific application examples will be described later, but are not limited to these. The present invention can be applied to all devices having the above-mentioned characteristics. For example, as types of rolling bearings to which the diagnostic method of the present invention can be applied, deep groove ball bearings, angular contact ball bearings, tapered roller bearings, cylindrical roller bearings, self-aligning roller bearings, etc. can also be cited.

[0041] [Physical Model]

[0042] use Figure 1 , Figure 2 The contact state between the components of the device to which the diagnostic method of this embodiment is applied will be described. Figure 1 represents the physical model when circular contact is made. In addition, Figure 2 represents the physical model when elliptical contact is made. The basic concept is the same, so it is used here Figure 1 Provide explanation.

[0043] Figure 1 This is a diagram showing the physical model of the ball and disk in the device when they are in rolling contact. The upper side of the figure shows the diagram observed from the x-axis direction, and the right side of the figure shows the diagram observed from the y-axis direction. It should be noted that, in order to simplify the description, an example is shown in which one of the contacting parts (the ball) has a curved surface shape and the other (the disk) has a flat surface shape, and they are in contact. However, it is also possible to have a structure in which both have curved surfaces and are in contact. In the case of such a structure, Figure 2 The physical model shown becomes a more approximate model.

[0044] The h axis represents the oil film thickness direction, and the x axis and y axis represent directions orthogonal to the oil film thickness direction. Figure 1 The variables shown are as follows.

[0045] S1: Hertz contact area (Hertz contact area)

[0046] c: Hertz contact circle radius (=√(S1 / π))

[0047] α: Oil film rupture rate (metal contact ratio) (0≤α<1)

[0048] r b : The radius of the spherical piece

[0049] αS1: Actual contact area (rupture area of ​​oil film)

[0050] h: Oil film thickness (x-axis direction, y-axis direction)

[0051] h1: Oil film thickness in the Hertzian contact area

[0052] h2: Maximum oil film thickness around the contact area

[0053] In the Hertzian contact region, the ratio of the area of ​​metal contact to the area of ​​non-contact is α:(1-α). In addition, in the ideal state where the ball and the disk are not in contact, α = 0. At this time, when y = 0, h>0. Similarly, when x = 0, h>0.

[0054] exist Figure 1 In the upper graph shown, the oil film thickness h is expressed by, for example, the following equation.

[0055] h=0(-αS1 / 2≤y≤αS1 / 2)

[0056] h=h1(-c≤y<-αS1 / 2, or αS1 / 2 <y≤c)

[0057] h=h1+√(r b 2 -c 2 )-√(r b 2 -y 2 ) (-r b ≤y<-c or c <y≤r b ) (1)

[0058] Similarly, in Figure 1 In the graph on the right side shown, the oil film thickness h is expressed by the following formula.

[0059] h=0(-αS1 / 2≤x≤αS1 / 2)

[0060] h=h1(-c≤x<-αS1 / 2, or αS1 / 2 <x≤c)

[0061] h=h1+√(r b 2 -c 2 )-√(r b 2 -x 2 ) (-r b ≤x<-c or c <x≤r b ) (2)

[0062] in addition, Figure 2 The variables in are as follows.

[0063] a': The radius of the Hertzian contact ellipse in the y-axis direction

[0064] b': Radius of the Hertzian contact ellipse in the x-axis direction

[0065] r x ￣: The radius of the ellipse of the spherical piece in the x-axis direction

[0066] r y ￣: The radius of the ellipse of the spherical piece in the y-axis direction

[0067] h2: The thickness of the middle of the maximum oil film thickness around the contact area

[0068] h3: Maximum oil film thickness around the contact area

[0069] In addition, when using Figure 2 In the case of the physical model, since the spherical piece becomes an ellipse, a part of the mathematical formula is replaced accordingly. That is, although the description is omitted here, in the use of Figure 2 In the case of a model, the ellipse formula can be applied. Therefore, other calculation formulas can also be used according to the assumed physical model, the structure of the bearing device as the object, etc. In addition, in the above, a two-dimensional calculation formula is listed, but a three-dimensional calculation formula can also be used.

[0070] [Equivalent circuit]

[0071] Figure 3 It is expressed as an electrically equivalent circuit (equivalent circuit) Figure 1 Figure 1 shows the physical model shown in Figure 1. Figure 2 The physical model of is the same. The equivalent circuit E1 includes resistor R1, capacitor C1 and capacitor C2. Resistor R1 is equivalent to the resistor in the rupture area (=αS1). Capacitor C1 is equivalent to the capacitor formed by the oil film in the Hertz contact area, and is set to electrostatic capacitance C1. Capacitor C2 is equivalent to the peripheral ( Figure 1 -r b ≤y<-c and c<y≤r b 、-r b ≤x<-c and c<x≤r b The capacitor formed by the oil film is defined as the electrostatic capacitance C2. The Hertz contact area (= S1) forms Figure 3 The equivalent circuit E1 is a parallel circuit of resistor R1 and capacitor C1. In addition, the Hertz contact area is formed around Figure 3 The circuit of capacitor C2 in the equivalent circuit E1. Furthermore, by connecting these parallel circuits in parallel, an equivalent circuit E1 is formed. At this time, around the Hertz contact area ( Figure 1 -r b≤y<-c and c<y≤r b 、-r b ≤x<-c and c<x≤r b ) is filled with lubricant.

[0072] The impedance of the equivalent circuit E1 is represented by Z. Here, the AC voltage V applied to the equivalent circuit E1, the current I flowing through the equivalent circuit E1, and the complex impedance Z of the entire equivalent circuit E1 are represented by the following equations (3) to (5).

[0073] V=|V|exp(jωt) (3)

[0074] I=|I|exp(j(ωt-θ)) (4)

[0075] Z=V / I=|V / I|exp(jθ)=|Z|exp(jθ) (5)

[0076] j: imaginary number

[0077] ω: angular frequency of AC voltage

[0078] t: time

[0079] θ: Phase angle (phase shift between voltage and current)

[0080] [Overview of the impedance method]

[0081] First, before explaining the diagnostic method of this embodiment, a conventional impedance method as a comparative object is briefly explained. The impedance method used in Patent Document 1 and the like is also a method based on the above-mentioned physical model and equivalent circuit.

[0082] In the conventional impedance method, the oil film thickness h and the metal contact ratio α are calculated based on the complex impedance (Z, θ) obtained by applying a voltage to the measurement object. The oil film thickness h and the metal contact ratio α can be calculated using the values ​​calculated by the following formula. In the following formula, the average oil film thickness in the contact area S1 is used as the oil film thickness.

[0083] [Number 1]

[0084]

[0085] [Number 2]

[0086]

[0087] R 10 : Resistance value at rest (i.e., α = 1)

[0088] θ: Phase angle

[0089] |Z|: Impedance of the equivalent circuit under dynamic contact state

[0090] h￣: average oil film thickness

[0091] c: radius of the contact area

[0092] r b : The radius of the spherical piece

[0093] W(): Lambert W function

[0094] exp(): exponential function

[0095] π: Pi

[0096] ε: Dielectric constant of oil film (lubricant)

[0097] ω: angular frequency of AC voltage

[0098] Figure 4 This is a semi-logarithmic graph showing the analysis results obtained by using the measurement results and the actual roughness after the test based on the well-known μEHL (Elasto-Hydrodynamic Lubrication) analysis. Figure 8 The results are obtained by performing a test using two cylinders with the device described later and measuring using a conventional impedance method. The test conditions, measurement conditions, and analysis conditions are as follows.

[0099] (Test conditions)

[0100] Lubricant viscosity (ISO viscosity classification): VG320

[0101] Surface pressure: 2.25GPa

[0102] Introduction speed: 0.785 [m / s]

[0103] Sliding speed: 0[m / s]

[0104] Temperature: 50℃~100℃

[0105] Composite roughness (σ): 40, 120, 260 [nm]

[0106] (Impedance measurement conditions)

[0107] Applied voltage: 0.5[V]

[0108] AC frequency: 1[MHz]

[0109] (Analysis conditions)

[0110] Input roughness: 2.9×1.6[mm](Δx≈1.6μm)

[0111] Grid size: 512×512 (Δx≈3μm)

[0112] Calculation area: -2.5a~1.5a, -1.75b~1.75b

[0113] exist Figure 4 In the figure, the horizontal axis represents temperature T[°C], and the vertical axis represents oil film thickness h[nm]. In addition, as a comparative example, the solid line represents the calculation result based on the well-known Hamroc & Dowson film thickness calculation formula (hereinafter referred to as HD formula). As mentioned above, here, the test was conducted using three surface roughnesses (σ=40, 120, 260[nm]). The surface roughness here uses the composite roughness of each contact surface.

[0114] First, if we look at the measurement results based on the conventional impedance method, we can see that as the temperature increases, the measured value tends to be smaller than the calculation result of the HD formula, and this becomes more significant as the surface becomes rougher. Furthermore, as the temperature increases, the measurement results of the conventional impedance method deviate more from the calculation result of the HD formula.

[0115] Next, the influence of roughness is studied. Here, the calculated oil film thickness h obtained by formula HD is H-D The ratio of roughness σ is Λ(=h H-D / σ). Figure 5 It is shown from other angles Figure 4 The calculation results of . Figure 5 In the figure, the horizontal axis represents Λ, and the vertical axis represents the oil film thickness h calculated by the conventional impedance method and the calculated oil film thickness h H-D According to Figure 5 In the range of 3≤Λ, the same calculation results can be obtained regardless of the roughness, so the influence of roughness is small. The oil film thickness h and h calculated by the conventional impedance method are H-D The ratio is approximately 1. However, as Λ becomes smaller, the influence of roughness becomes greater. That is, the calculated film thickness h is smaller than the calculated oil film thickness h H-D (h / h H-D becomes smaller).

[0116] Therefore, in the present invention, the roughness of the contact area is focused. In particular, Figure 5 As shown in FIG. 1 , a method for improving the conventional impedance method is proposed, assuming that the roughness has a significant effect when the value of Λ is equal to or less than a certain value.

[0117] [Roughness treatment]

[0118] First, the processing of the roughness of the contact region S1 in the conventional impedance method will be described. Figure 6 FIG. 1 is a schematic diagram of the contact area and its surroundings for explaining the surface roughness in the conventional impedance method. Figure 1 As shown, in the contact area S1, two components (here, the ball plate and the disk) are in contact, and the periphery thereof is filled with lubricant. Figure 6 (a) shows the actual mixed lubrication state. Here, for the sake of simplicity, the composite roughness is used to represent the case where the surface of the ball plate is rough and the disk plate is smooth.

[0119] Relative to Figure 6 (a) status, Figure 6 (b) shows the geometric model used in the conventional impedance method. Figure 6 (a) The status as Figure 6 The measurement is performed by treating the state equivalent to the geometric model shown in (b). That is, the average value of the oil film thickness h in the contact area S1, that is, the average oil film thickness ĥ is used.

[0120] and Figure 6 The capacitance C corresponding to the model (a) a It can be calculated by the following expression.

[0121] [Number 3]

[0122]

[0123] and Figure 6 (b) The geometric model corresponds to the capacitance C b It can be calculated by the following expression.

[0124] [Number 4]

[0125]

[0126] Actual C a and C b The value of is different, C a >C b In addition, in the conventional impedance method, the oil film thickness h1 and the average oil film thickness ĥ are calculated by the following equations (10) and (11).

[0128] [Number 5]

[0129]

[0130] [Number 6]

[0131]

[0132] In C a >C b In the case of C a Replace C bWhen h1 is calculated by C, the calculated oil film thickness is naturally different. a and C b The greater the deviation of the value, the lower the accuracy of the calculated oil film thickness.

[0133] Therefore, in this embodiment, the surface roughness around the contact region is taken into consideration by the following processing. Figure 7 Schematic diagram of the contact area and its surroundings for explaining the surface roughness in the impedance method of the present invention. Figure 1 As shown, in the contact area S1, two components (here, the ball plate and the disk) are in contact and are filled with lubricant around them. Figure 7 (a) shows the actual mixed lubrication state. Here, for the sake of simplicity, the composite roughness is used to represent the case where the surface of the ball plate is rough and the disk plate is smooth.

[0134] Relative to Figure 6 In the state of (a), in this embodiment, the surface roughness is assumed to be normally distributed, and an equation taking the surface roughness into consideration is defined. That is, the probability density of the interval between the two surfaces when a Gaussian distribution is assumed is calculated by the following equation.

[0135] [Number 7]

[0136]

[0137] Figure 7 (b) is a graph showing the relationship between film thickness and occurrence probability when the surface roughness is assumed to be normally distributed. Figure 7 In (b), the vertical axis represents the film thickness h, and the horizontal axis represents the occurrence probability. Figure 1 As described above, α corresponds to the breakage rate of the oil film. Here, the surface roughness, that is, the oil film thickness distribution is represented by the inverse function of the following cumulative distribution function.

[0138] [Number 8]

[0139]

[0140] F: Cumulative distribution probability (0-1)

[0141] The region where the oil film exists is a region where h>0. In this region, by performing area integration of ε / h, the electrostatic capacitance C1 of the contact surface can be calculated by the following equation (14).

[0142] [Number 9]

[0143]

[0144] Here, it is not easy to calculate directly using the above formula (14). Therefore, in this embodiment, by approximating and transforming the above formula as follows, a certain measurement accuracy of the oil film thickness μ is achieved and the calculation load is suppressed. Formula (15) represents an approximate formula based on Taylor expansion. In addition, formula (16) is an approximate formula of C1 obtained by transforming formula (14) based on formula (15).

[0145] [Number 10]

[0146]

[0147] [Number 11]

[0148]

[0149] [Number 12]

[0150]

[0151] [Number 13]

[0152]

[0153] At this time, according to the following formula (19), formula (18) becomes the following formula (20).

[0154] [Number 14]

[0155]

[0156] [Number 15]

[0157]

[0158] Therefore, in this embodiment, the oil film thickness μ in the contact region S1 is calculated using equations (17) and (20).

[0159] In addition, as described above, in this embodiment, the smooth surface and the rough surface are in contact, and the standard deviation of the surface roughness of the rough surface, that is, the root mean square roughness R q Used as σ. When the two surfaces in contact are rough surfaces, it can be regarded as a contact between a rough surface and a smooth surface having a composite roughness. In this case, when the roughness of each of the two rough surfaces is set to σ1 and σ2, the composite surface roughness can be calculated by the following formula.

[0160] [Number 16]

[0161]

[0162] In addition, in the above, the line roughness R is listed q , but the surface roughness Sq The same idea can also be applied.

[0163] In addition, in this embodiment, the probability density function is defined by assuming that the surface roughness is Gaussian distributed. However, this is not limited to this. As long as the distribution of the surface roughness can be defined, it can also be defined based on a distribution other than Gaussian distribution and the definition can be applied. In the case of other than Gaussian distribution, the following formula (22) can be used to calculate the capacitance C1.

[0164] [Number 17]

[0165]

[0166] In addition, as described above, the distribution of surface roughness can also be expressed using an approximation. In addition, the formula (17), formula (20), or formula (22) can be switched to be used according to the structure of the rolling device as the diagnosis object. That is, since the allowable accuracy and processing load may be different depending on the structure of the rolling device and the purpose of diagnosis, the above formulas can be used separately.

[0167] [Application Examples]

[0168] Hereinafter, application examples using the diagnostic method of the present embodiment will be described.

[0169] [Device structure]

[0170] Figure 8 This is a schematic configuration diagram showing an example of the overall configuration when the diagnostic method according to the present embodiment is applied. Figure 8 (a) is a diagram of the rolling device 800 as viewed along the y-axis direction, and schematically shows the interior of a connecting portion 810 constituting the rolling device 800. Figure 8 (b) is a diagram showing the rolling device 800 along the z-axis direction orthogonal to the y-axis direction. Figure 8 In the embodiment, a rolling device 800, an LCR meter 830 and a diagnostic device 840 for performing the diagnosis are provided. Figure 8 The structure shown is an example, and a different structure may be used depending on the structure of the rolling device 800 and the like.

[0171] The rolling device 800 includes a rotating shaft 822 composed of two cylindrical shafts partially including an insulating joint. The rotating shaft 822 is provided with a bearing portion 820 composed of a plurality of rolling bearings 821. Figure 8 In the example, three rolling bearings 821 (here, ball bearings) are provided on the rotating shaft 822 so as to be able to roll. A load is applied to the bearing portion 820 from a certain direction. In addition, the rotating shaft 822 is inserted into the connecting portion 810 and rotates in conjunction with each other inside the connecting portion 810. Figure 8 Although not shown, a driving motor serving as a power source for the rotating shaft 822 is connected to one or both of the two cylinders. Figure 8 In the example of (a), the cylinder on the right rotates counterclockwise, and the cylinder on the left rotates clockwise. A seal 816 is provided at the portion where the rotating shaft 822 is inserted to prevent leakage of the lubricant 813 filled in the connecting portion 810 and entry of dirt.

[0172] In the connection part 810, the contact member 811 provided at the front end of the rotating shaft 822 contacts at the position A. A thermocouple 812 is provided in the connection part 810, and is configured to be able to measure the peripheral temperature of the position A. A lubricant 813 is filled in the chamber 815, and is configured to reduce the friction of the contact area at the position A. The lubrication method is not particularly limited, for example, grease lubrication, oil lubrication, etc. are used. There is no particular limitation on the type of lubricant. In addition, a heater 814 is provided that can adjust the temperature in the chamber 815.

[0173] The rotating shaft 822 is connected to the LCR meter 830 via a rotary connector (not shown). The structure of the rotary connector is not particularly limited. The LCR meter 830 is also electrically connected to the contact member 811 and also functions as an AC power source for the contact member 811.

[0174] The diagnostic device 840 operates as a detection device capable of executing the detection method of the present embodiment. During diagnosis, the diagnostic device 840 uses the angular frequency ω and the AC voltage V of the AC power source as inputs to indicate to the LCR meter 830, and obtains the impedance |Z| (|Z| represents the absolute value of Z) and the phase angle θ of the rolling device 800 from the LCR meter 830 as corresponding outputs. Then, the diagnostic device 840 uses these values ​​to diagnose the rolling device 800.

[0175] The diagnostic device 840 can be realized, for example, by an information processing device that includes a control device, a storage device, and an output device (not shown). The control device can be composed of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a DSP (Digital Single Processor), or a dedicated circuit. The storage device is composed of volatile and non-volatile storage media such as HDD (Hard Disk Drive), ROM (Read Only Memory), and RAM (Random Access Memory), and can input and output various information according to instructions from the control device. The output device is composed of a display device such as a speaker, a lamp, or a liquid crystal display, and reports to the operator according to instructions from the control device. The notification method of the output device is not particularly limited, for example, it can be an auditory notification based on sound, or it can be a visual notification based on screen output. In addition, the output device can be a network interface with a communication function, and can also perform a notification action by sending data to an external device (not shown) via a network (not shown). The notification content here is not limited to, for example, a notification when an abnormality is detected when abnormality diagnosis is performed based on the detection result, but may also include a notification indicating that the scrolling device 800 is normal.

[0176] [Processing Flow]

[0177] Fig. 9 This process is executed by the diagnostic device 840, and can be realized by, for example, a control device (not shown) included in the diagnostic device 840 reading a program for realizing the process of this embodiment from a storage device (not shown) and executing the program.

[0178] In step S901, the diagnostic device 840 controls the rolling device 800 to apply a load in a predetermined direction. Figure 8 The load is applied in the direction indicated by the arrow. In addition, the control of the applied load may be performed by a device different from the diagnostic device 840. At this time, the phase and impedance in the static contact state are measured.

[0179] In S902, the diagnostic device 840 starts rotating the rotating shaft 822 by means of a motor (not shown). The motor may be controlled by a device other than the diagnostic device 840.

[0180] In S903, diagnostic device 840 controls LCR meter 830 to supply AC voltage V of angular frequency ω to rolling device 800 using an AC power source (not shown) provided in LCR meter 830. Thus, AC voltage V of angular frequency ω is applied to rolling device 800.

[0181] In S904, the diagnostic device 840 obtains the impedance |Z| and the phase angle θ as outputs corresponding to the input of S903 from the LCR meter 830. That is, the LCR meter 830 outputs the impedance |Z| and the phase angle θ to the diagnostic device 840 as the detection results of the rolling device 800 corresponding to the input, that is, the AC voltage V and the angular frequency ω of the AC voltage.

[0182] In S905 , the diagnostic device 840 applies the impedance |Z| and the phase angle θ acquired in S904 and the angular frequency ω of the AC voltage used in S903 to the above-mentioned equations to derive the oil film thickness h and the rupture rate α.

[0183] In S906, the diagnostic device 840 uses the oil film thickness h and the rupture rate α derived in S905 to diagnose the lubrication state of the rolling device 800. In addition, the diagnostic method here can, for example, set a threshold value for the oil film thickness h and the rupture rate α, and judge the lubrication state by comparing with the threshold value. Then, this processing flow ends.

[0184] [Measurement results]

[0185] Below, use Figure 10 to Figure 12 The measurement results of the measurement method according to the present embodiment will be described. Fig.10 This is a semi-logarithmic graph showing the measurement results of the test using the measurement method of this embodiment and the calculation results of the HD formula. Figure 4 and Figure 5 The conditions are the same as described. Fig.10 In the figure, the horizontal axis represents temperature T[℃] and the vertical axis represents oil film thickness h. Figure 4 Likewise, here, three examples of composite roughness σ (σ=40, 120, 260 [nm]) are used.

[0186] Reference Fig.10 , when the composite roughness is σ=40 and σ=120, a value roughly equal to the calculated oil film thickness based on the formula of HD can be derived at any temperature. In addition, when the composite roughness is σ=260, a value higher than the calculated oil film thickness is derived, but it converges to a value of about 300nm, which is the same as σ. This means that in the presence of roughness, the oil film will not become smaller than the roughness due to the contact of the protrusion caused by the surface roughness. Therefore, it is considered that the measurement result of the method of this embodiment is appropriate.

[0187] Fig.12 Shown from other angles Fig.10 The calculation results of Figure 5 Corresponding. Here, Fig.11 It is shown in Figure 5 The chart and Fig.12 The scale (vertical axis) of is consistent. Fig.12 In the figure, the horizontal axis represents Λ, and the vertical axis represents the oil film thickness h calculated by the measuring method of this embodiment and the calculated oil film thickness h H-D Referring to the existing method Fig.11 (as well as Figure 5 ) and the present method Fig.12 In the conventional method, in the region where Λ is small (Λ<3), the oil film thickness is calculated to be small. This is considered to be because the increase in the electrostatic capacitance of the contact surface due to the influence of roughness cannot be considered. On the other hand, in the method of this embodiment, a value close to the calculated oil film thickness can be calculated in a wider range (more specifically, 1<Λ<3) than in the conventional method.

[0188] In addition, if Fig.12 As shown, in the region of Λ<1, h / h H-D The value of is greater than 1. This is considered to be due to the influence of roughness. The oil film thickness (i.e., the distance between the two surfaces) will not be further reduced, and the actual oil film thickness is greater than h, which is the calculation result on the smooth surface. H-D Therefore, it is considered that the measurement result based on the method of this embodiment is appropriate.

[0189] As described above, according to the present embodiment, the oil film thickness of the device and the metal contact ratio between components can be detected with higher accuracy than conventional methods.

[0190] <Other Implementation Methods>

[0191] In addition, in the present invention, the following processing can also be implemented: a program or application for implementing the functions of one or more of the above-mentioned embodiments is supplied to a system or device using a network or storage medium, and one or more processors in a computer of the system or device read and execute the program.

[0192] Alternatively, the present invention may be realized by a circuit that realizes one or more functions (for example, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array)).

[0193] Thus, the present invention is not limited to the above-mentioned embodiments, and combining the structures of the embodiments with each other, and changing and applying them by those skilled in the art based on the description in the specification and known technologies are also the intended contents of the present invention and are included in the scope of the protection required.

[0194] As described above, the following matters are disclosed in this specification.

[0195] (1) A measuring method, characterized in that a state of a device that lubricates parts with a lubricant is measured,

[0196] applying an AC voltage to a circuit consisting of components lubricated by the lubricant,

[0197] measuring the impedance and phase angle of the circuit when the AC voltage is applied,

[0198] deriving the oil film thickness and the metal contact ratio between the components based on the impedance and the phase angle,

[0199] The oil film thickness and the metal contact ratio between the components are derived using a probability density function of the surface roughness between the components in the contact region between the components using a calculation formula that defines the capacitance of the contact region.

[0200] According to this configuration, the oil film thickness of the device and the metal contact ratio between components can be detected with higher accuracy than conventional methods.

[0201] (2) The measuring method according to (1), characterized in that

[0202] The calculation formula for deriving the capacitance C1 of the contact area is:

[0203] [Number 18]

[0204]

[0205] According to this configuration, the electrostatic capacitance of the contact region can be calculated with high accuracy based on the distribution of the roughness of the contact region.

[0206] (3) The measuring method according to (1), characterized in that

[0207] The calculation formula is a calculation formula that defines the surface roughness between the components using Gaussian distribution.

[0208] According to this configuration, the capacitance of the contact region can be calculated with high accuracy using Gaussian distribution as the distribution of the roughness of the contact region.

[0209] (4) The measuring method according to (3), characterized in that

[0210] The calculation formula for deriving the electrostatic capacitance C1 of the contact area is:

[0211] [Number 19]

[0212]

[0213] According to this configuration, the capacitance of the contact region can be calculated with high accuracy using Gaussian distribution as the distribution of the roughness of the contact region.

[0214] The measuring method as described in (4) is characterized in that

[0215] The calculation formula for deriving the oil film thickness μ is:

[0216] [Number 20]

[0217]

[0218] [Number 21]

[0219]

[0220] According to this configuration, the capacitance of the contact region can be calculated with high accuracy using Gaussian distribution as the distribution of the roughness of the contact region.

[0221] (6) The measuring method according to any one of (1) to (5), characterized in that

[0222] The oil film thickness and the metal contact ratio are further used to diagnose the status of the device.

[0223] According to this configuration, it is possible to diagnose the device using the oil film thickness and the metal contact ratio with higher accuracy than before.

[0224] (7) A measuring device, characterized in that the measuring device measures the state of a device that lubricates parts with a lubricant, and comprises:

[0225] an acquisition unit that applies an AC voltage to a circuit composed of components lubricated by the lubricant and acquires an impedance and a phase angle of the circuit when the AC voltage is applied; and

[0226] a deriving unit, wherein the deriving unit derives the oil film thickness and the metal contact ratio between the components based on the impedance and the phase angle,

[0227] The oil film thickness and the metal contact ratio between the components are derived using a probability density function of the surface roughness between the components in the contact region between the components using a calculation formula that defines the capacitance of the contact region.

[0228] According to this configuration, the oil film thickness of the device and the metal contact ratio between components can be detected with higher accuracy than conventional methods.

[0229] (8) A program, characterized in that a computer is caused to function as an acquisition unit and a derivation unit,

[0230] The acquisition unit applies an AC voltage to a circuit formed by a component lubricated by the lubricant, and acquires an impedance and a phase angle of the circuit when the AC voltage is applied.

[0231] The deriving unit derives the oil film thickness and the metal contact ratio between the components based on the impedance and the phase angle,

[0232] The oil film thickness and the metal contact ratio between the components are derived using a probability density function of the surface roughness between the components in the contact region between the components using a calculation formula that defines the capacitance of the contact region.

[0233] According to this configuration, the oil film thickness of the device and the metal contact ratio between components can be detected with higher accuracy than conventional methods.

[0234] In the above, various embodiments are described with reference to the accompanying drawings, but the present invention is certainly not limited to this example. As long as a person skilled in the art can think of various variations or modifications within the scope described in the claims, it is obvious that these variations or modifications also belong to the technical scope of the present invention. In addition, the various constituent elements in the above-mentioned embodiments may also be arbitrarily combined within the scope of the gist of the invention.

[0235] Various embodiments have been described above, but the present invention is certainly not limited to these examples. As long as one skilled in the art can think of various variations or modifications within the scope described in the claims, it is obvious that these variations or modifications also belong to the technical scope of the present invention. In addition, within the scope of not departing from the gist of the invention, the various constituent elements in the above-mentioned embodiments may also be arbitrarily combined.

[0236] In addition, the present application is based on the Japanese patent application (Japanese Patent Application No. 2022-039415) filed on March 14, 2022, the contents of which are incorporated herein by reference.

[0237] Description of Reference Numerals

[0238] 800 Rolling Device

[0239] 810 Connection

[0240] 811 Contact parts

[0241] 812 Thermocouple

[0242] 813 Lubricant

[0243] 814 Heater

[0244] 815 Chamber

[0245] 816 Seals

[0246] 820 Bearing

[0247] 821 Rolling bearings

[0248] 822 Rotating axis

[0249] 830 LCR Meter

[0250] 840 Diagnostic Device

Claims

1. A determination method, characterized in that: Measure the status of a device that uses lubricants to lubricate parts. applying an AC voltage to a circuit consisting of components lubricated by the lubricant, measuring the impedance and phase angle of the circuit when the AC voltage is applied, deriving the oil film thickness and the metal contact ratio between the components based on the impedance and the phase angle, The oil film thickness and the metal contact ratio between the components are derived using a calculation formula obtained by using the electrostatic capacitance that defines the contact area using a probability density function of the surface roughness between the components in the contact area between the components.

2. The measuring method according to claim 1, characterized in that The calculation formula for deriving the electrostatic capacitance C1 of the contact area is: [Number 1] S1: Hertz contact area (Hertz contact area) α: Oil film rupture rate (metal contact ratio) (0≤α<1) ε: Dielectric constant of oil film (lubricant) h(F): Oil film thickness distribution F: Cumulative distribution probability (0~1).

3. The measuring method according to claim 1, characterized in that The calculation formula is a calculation formula that defines the surface roughness between the components using Gaussian distribution.

4. The assay method according to claim 3, wherein The calculation formula for deriving the electrostatic capacitance C1 of the contact area is: [Number 2] S1: Hertz contact area (Hertz contact area) α: Oil film rupture rate (metal contact ratio) (0≤α<1) ε: Dielectric constant of oil film (lubricant) F: Cumulative distribution probability (0-1) μ: Oil film thickness σ: surface roughness.

5. The assay method according to claim 4, wherein The calculation formula for deriving the oil film thickness μ is: [Number 3] h1: Oil film thickness.

6. The measuring method according to any one of claims 1 to 5, characterized in that The oil film thickness and the metal contact ratio are further used to diagnose the status of the device.

7. A measuring device, characterized in that: The measuring device measures the state of a device that lubricates components using a lubricant, and has: an acquisition unit that applies an AC voltage to a circuit formed by a component lubricated by the lubricant and acquires an impedance and a phase angle of the circuit when the AC voltage is applied; as well as a deriving unit, wherein the deriving unit derives the oil film thickness and the metal contact ratio between the components based on the impedance and the phase angle, The oil film thickness and the metal contact ratio between the components are derived using a calculation formula obtained by using the electrostatic capacitance that defines the contact area using a probability density function of the surface roughness between the components in the contact area between the components.

8. A program, characterized in that Make the computer function as an acquisition unit and an export unit, The acquisition unit applies an AC voltage to a circuit formed by a component lubricated by a lubricant, and acquires an impedance and a phase angle of the circuit when the AC voltage is applied. The deriving unit derives the oil film thickness and the metal contact ratio between the components based on the impedance and the phase angle, The oil film thickness and the metal contact ratio between the components are derived using a calculation formula obtained by using the electrostatic capacitance that defines the contact area using a probability density function of the surface roughness between the components in the contact area between the components.

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