Condition diagnostic method, condition diagnostic device and computer readable storage medium

Abstract

CONDITION DIAGNOSTIC METHOD, CONDITION DIAGNOSTIC DEVICE AND PROGRAM. The present invention relates to a condition diagnostic method comprising: a measurement step for measuring the relative dielectric constant of a lubricant by applying a voltage to the lubricant while varying the frequency of an AC power source; a parameter derivation step that indicates electrical properties of the lubricant by applying the relative dielectric constant measured in the measurement step to a theoretical formula; and a diagnostic step for diagnosing a condition of the lubricant using the parameters.

Description

1 / 28 CONDITION DIAGNOSTIC METHOD, CONDITION DIAGNOSTIC DEVICE AND COMPUTER-READABLE STORAGE MEDIUM TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a condition diagnostic method, a condition diagnostic device and a program. BACKGROUND OF THE INVENTION

[0002] Conventionally, when diagnosing the condition of materials, methods such as analysis of physical properties (e.g., apparent viscosity), analysis of chemical components (e.g., degree of deterioration), and structural analysis using a microscope are used. Such methods generally require complicated operations. Furthermore, it is difficult to perform the methods described above non-destructively on the target, and in many cases, the target to be diagnosed is discarded.

[0003] On the other hand, there is a method for performing impedance analysis using an AC power supply. Impedance analysis can be used to make it possible to derive the electrical properties of the material.

[0004] For example, Patent Literature 1 describes a method for using blood as a target to be analyzed and measuring the dielectric constant of the blood while varying the frequency to measure damage to blood cells. Furthermore, Patent Literature 2 describes a method for evaluating variations in the composition of an extraction solvent based on the frequency characteristics of the relative dielectric constant and relative dielectric loss factor. LIST OF QUOTES PATENT LITERATURE Patent Literature 1: JP-A-2008-215901 Patent Literature 2: JP-A-H7-239316 Petition 870260049536, dated 05 / 25 / 2026, page 6 / 77 2 / 28 SUMMARY OF THE INVENTION TECHNICAL PROBLEM

[0005] The materials used in real devices include, for example, lubricants. Understanding the condition of the lubricant is extremely useful in preventing damage or similar issues in devices that use lubricant. On the other hand, it is difficult to observe the target as a lubricant when removing the target from the device in a non-destructive manner.

[0006] In view of the above problems, an objective of the present invention is to provide a method for easily diagnosing the condition of a lubricant without destroying the target to be diagnosed. SOLUTION TO THE PROBLEM

[0007] In order to solve the above problems, the present invention has the following configuration. In other words, a condition diagnostic method is provided that includes: a measurement step to measure the relative dielectric constant of a lubricant by applying a voltage to the lubricant while varying the frequency of an AC power source; a parameter derivation step that indicates electrical properties of the lubricant by applying the relative dielectric constant measured in the measurement step to a theoretical formula; and a diagnostic step to diagnose a condition of the lubricant using the parameters.

[0008] Furthermore, another aspect of the present invention has the following structure. In other words, a condition diagnostic device is provided that includes: a measuring unit for measuring the relative dielectric constant of a lubricant by applying a voltage to the lubricant while varying the frequency of an AC power source; a derivation unit for deriving parameters indicating electrical properties of the lubricant by applying the relative dielectric constant measured in the measuring unit to a theoretical formula; and a diagnostic unit for diagnosing a condition of the lubricant. Petition 870260049536, dated 05 / 25 / 2026, page 7 / 77 3 / 28 using the parameters.

[0009] Furthermore, another aspect of the present invention has the following structure. In other words, a program is provided to cause a computer to perform a measurement step to measure the relative dielectric constant of a lubricant by applying a voltage to the lubricant while varying the frequency of an AC power source, a derivation step to derive parameters that indicate the electrical properties of the lubricant by applying the relative dielectric constant measured in the measurement step to a theoretical formula, and a diagnostic step to diagnose a condition of the lubricant using the parameters. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0010] According to the present invention, it is possible to easily diagnose the condition of a lubricant without destroying the target to be diagnosed. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a conceptual diagram showing a configuration of a lubricant that is a target to be diagnosed and an AC power source according to the present invention.

[0012] Figure 2 is a diagram to explain an equivalent circuit composed of a lubricant that is a target to be diagnosed and an AC power source according to the present invention.

[0013] Figure 3 is a schematic configuration diagram showing an example of a device configuration according to the present invention.

[0014] Figures 4A and 4B are diagrams to explain the relationship between frequency and the relative dielectric constant and relative dielectric loss factor.

[0015] Figures 5A and 5B are diagrams to explain the derivation Petition 870260049536, dated 05 / 25 / 2026, page 8 / 77 4 / 28 of parameters through adjustment to a theoretical formula (Debye type).

[0016] Figures 6A and 6B are diagrams to explain the derivation of parameters through fitting to a theoretical formula (Cole-Cole type).

[0017] Figures 7A and 7B are diagrams to explain the derivation of parameters through fitting to a theoretical formula (enhanced Cole-Cole type).

[0018] Figure 8 is a flowchart of the diagnostic processing of a condition according to an embodiment of the present invention.

[0019] Figures 9A and 9B are diagrams to explain the relationship between a lubricant condition and the parameters.

[0020] Figure 10 is a diagram to explain the relationship between a lubricant condition and the parameters.

[0021] Figure 11 is a diagram to explain the relationship between a thickener and resistance to relaxation.

[0022] Figures 12A and 12B are diagrams to explain the thickener roll state.

[0023] Figures 13A and 13B are diagrams to explain the relationship between frequency and parameters according to a thickener fiber state.

[0024] Figure 14 is a diagram to explain the relationship between frequency and parameters according to the fiber state of the thickener.

[0025] Figures 15A and 15B are diagrams to explain the relationship between the deterioration of the base oil and the relative dielectric constant.

[0026] Figures 16A and 16B are diagrams to explain the relationship between base oil deterioration and the relative dielectric loss factor.

[0027] Figures 17A and 17B are diagrams to explain the relationship between grease deterioration and the parameters.

[0028] Figures 18A and 18B are diagrams to explain the relationship Petition 870260049536, dated 05 / 25 / 2026, page 9 / 77 5 / 28 between the water content in the grease and the parameters.

[0029] Figures 19A and 19B are diagrams to explain the relationship between the water content in grease and the average dielectric constant.

[0030] Figure 20 is a diagram to explain the relationship between the amount of iron powder in grease and the relative dielectric loss factor. DESCRIPTION OF MODALITIES

[0031] The embodiments of the present invention will be described below with reference to the drawings. Furthermore, the embodiment described below is an embodiment for describing the present invention and should not be interpreted as limiting the present invention. Not all configurations are essential configurations for solving the problems of the present invention. In addition, in each drawing, the same component is indicated by the same reference number to indicate the correspondence relationship. Target to be Diagnosed

[0032] In this embodiment, a lubricant used for component lubrication will be described as an example of a target to be diagnosed. The lubricant used in this document is a grease that has the characteristic of causing dielectric relaxation. More specifically, a lithium 12-hydroxystearate grease, and so on, can be considered a target. The grease is generally composed of a base oil, a thickener, and additives. Although the details are described later, the values ​​of the parameters indicating the electrical properties will fluctuate depending on the configuration or condition of the grease.

[0033] In the present embodiment, assuming that the grease is in a bulk state, the parameters indicating the electrical properties corresponding to the internal condition are derived and the condition of the grease is diagnosed using these parameters. Figure 1 is a conceptual diagram showing the configuration of a lubricant. Petition 870260049536, dated 05 / 25 / 2026, page 10 / 77 6 / 28 (in this document, grease) and an AC power source when evaluating (measuring) the electrical properties of the lubricant according to this embodiment. Electrical power is supplied from an AC power source 10 to the grease 12 filled between electrodes 11. Furthermore, the distance between electrodes 11 in this document can be configured on the order of mm, for example.

[0034] Figure 2 is a diagram showing an electrically equivalent electrical circuit around the grease 12 shown in Figure 1. An electrical circuit E has a configuration in which a capacitor C composed of grease 12 and a resistance R caused by peripheral elements are connected in parallel. Furthermore, the impedance of the electrical circuit E is indicated by Z. In this document, the AC voltage V applied to the electrical circuit E, the current I flowing through the electrical circuit E, and the complex impedance Z of the entire electrical circuit E are expressed by Equations (1) to (3) below. V = |V|ex ρ(|ω1) ... (1) I = |I|exp^t - j9) ... (2) Z = V / I = |V / I|exp(j9) = |Z|exp(j9) ... (3) j: imaginary number ω: angular frequency of the voltage t: time θ: phase angle (phase deviation between voltage and current) Device Configuration

[0035] Figure 3 is a schematic configuration diagram showing an example of the general configuration of a system to which the condition diagnostic method according to the present embodiment can be applied. Figure 3 shows a condition diagnostic device 30 using the condition diagnostic method according to the present embodiment, a measuring device 31 and material inclusions 32, including grease 12, which is Petition 870260049536, dated 05 / 25 / 2026, page 11 / 77 7 / 28 a target to be diagnosed. Note that the configuration shown in Figure 1 is an example and a different configuration may be used depending on the target to be diagnosed and so on.

[0036] The measuring device 31 includes the AC power supply shown in Figure 1 and applies power to the grease 12 contained in the material inclusions 32 during diagnosis.

[0037] The condition diagnostic device 30 instructs the measuring device 31 to use the AC voltage V of angular frequency ω from the AC power source 10 as the power input value to be applied to the grease 12 and acquires the impedance |Z| (|Z| indicates the absolute value of Z) of the grease 12 and the phase angle θ from the measuring device 31 as corresponding results (measurement values). The condition diagnostic device 30 then uses these values ​​to derive parameters that indicate the electrical properties of the grease 12 and then performs the diagnosis. Details of the parameter types and derivation methods will be described later.

[0038] The condition diagnostic device 30 can be embodied, for example, by an information processing device that includes a control device, a storage device, and a results display device (not shown).The control device may consist of a central processing unit (CPU), a microprocessing unit (MPU), a digital single processor (DSP), a dedicated circuit, or similar. The storage device consists of volatile and non-volatile storage media, such as a hard disk drive (HDD), read-only memory (ROM), and random access memory (RAM), and it is possible to insert and send various information to and from the storage device accordingly. Petition 870260049536, dated 05 / 25 / 2026, page 12 / 77 8 / 28 instructions from the control device. The results display device consists of a speaker, a light, a display device such as a liquid crystal display or similar, and notifies the operator according to instructions from the control device. The method of displaying results by the results display device is not particularly limited. In addition, the results display device may be a network interface with a communication function and may perform a results display operation by transmitting data to an external device (not shown) via a network (not shown).

[0039] Furthermore, the forms of the condition diagnostic device 30 and the measuring device 31 are not particularly limited. For example, the condition diagnostic device 30 and the measuring device 31 can be wired or wirelessly connected. Alternatively, the condition diagnostic device 30 and the measuring device 31 can be integrated. Alternatively, the user can be responsible for data input / transmission between the condition diagnostic device 30 and the measuring device 31. Relative Dielectric Constant and Relative Dielectric Loss Factor

[0040] Figures 4A and 4B are diagrams to explain the trend of variations in the relative dielectric constant and the relative dielectric loss factor according to variations in frequency. In this document, as described above, lithium 12-hydroxystearate grease will be described as an example of grease 12.Using the configuration shown in Figure 3, the dielectric relaxation phenomenon is confirmed by performing a frequency sweep and measuring the relative dielectric constant Er' and the relative dielectric loss factor Er'' of grease 12.

[0041] In Figure 4A, the horizontal axis indicates the frequency [Hz] and the Petition 870260049536, dated 05 / 25 / 2026, page 13 / 77 9 / 28 The vertical axis indicates the relative dielectric constant Er'. Figure 4A shows experimental values ​​obtained with grease 12. As shown in Figure 4A, the relative dielectric constant Er' tends to decrease (decrease monotonically) as the frequency increases.

[0042] In Figure 4B, the horizontal axis indicates the frequency [Hz] and the vertical axis indicates the relative dielectric loss factor Er''. Figure 4B shows experimental values ​​obtained with grease 12. As shown in Figure 4B, the relative dielectric loss factor Er'' decreases as the frequency increases, then tends to increase and then decreases again.

[0043] In this embodiment, the following seven parameters should be derived as parameters that indicate the electrical properties of grease 12. Ehd: Relative dielectric constant in the low-frequency limit. Er~ : Relative dielectric constant in the high-frequency limit Er0-Er~: Resistance to relaxation Er'-: Average dielectric constant τ: Relaxation time [s] β: Constant indicating the relaxation time distribution σ0: DC conductivity [S / m]

[0044] Although the details are described later, the above parameters change depending on the internal condition of the grease 12. Therefore, by deriving the parameters, it is possible to use the parameters to diagnose the internal condition of the grease. Adjustment to the Theoretical Formula

[0045] The electrical properties of grease 12 based on the phenomenon of dielectric relaxation tend to vary, as shown in Figures 4A and 4B. To specify this tendency for variation, several parameters are derived by fitting various theoretical formulas. Three theoretical formulas will be described in Petition 870260049536, dated 05 / 25 / 2026, page 14 / 77 10 / 28 of this document are given as examples, but the present invention is not limited to them. For example, other theoretical formulas may be used, provided that each of the seven parameters above can be derived more accurately. Unless otherwise specified, when the same symbols are shown for the symbols used in each theoretical formula, this means that the symbols are indicating the same thing. Debye type

[0046] The adjustment to the theoretical Debye-type formula will be described. The theoretical Debye-type formula is shown below. Mathematics 1 _ Ero-Eroor ~ ι+ω2τ2 trco ... (4) Mathematics 2 _ (ErO-£roo)á>Tr1+ωζτ2ω: Angular frequency of the voltage

[0047] Figures 5A and 5B compare the curve obtained by fitting the theoretical Debye-type formula and the experimentally obtained values. The experimental values ​​in Figures 5A and 5B are equal to those in Figures 4A and 4B, respectively. As shown in Figure 5B, the relaxation times τ (peak positions) coincide. On the other hand, non-coincident results are shown for other parameters. Cole-Cole type

[0048] The adjustment to the Cole-Cole type theoretical formula will be described. The Cole-Cole type theoretical formula is shown below. Mathematics 3 Petition 870260049536, dated 05 / 25 / 2026, page 15 / 77 11 / 28 Mathematics 4 Mathematics 5 X = 1η(ωτ) = 1η(2ττ / τ) ··· (8 ) π: Circumference ratio f: Frequency In: Logarithmic function

[0049] Figures 6A and 6B compare the curve obtained through fitting to the Cole-Cole type theoretical formula and the experimentally obtained values. The experimental values ​​in Figures 6A and 6B are equal to those in Figures 4A and 4B, respectively. As shown in Figure 6A, regarding the relative dielectric constant, the theoretical formula can express the trend of the experimental values ​​through fitting. On the other hand, with reference to Figure 6B, the relaxation times τ (peak position) correspond, however, as indicated by the dashed line, the results show the absence of correspondence between the theoretical and experimental values ​​regarding the trend of the relative dielectric loss factor in the low frequency range. Enhanced Cole-Cole Type

[0050] The adjustment to the theoretical formula of the enhanced Cole-Cole type based on the Cole-Cole type will be described. The theoretical formula of the enhanced Cole-Cole type is shown below. Note that Formulas (9) and (11) are the same as Formulas (6) and (8) shown in the Cole-Cole type. Mathematics 6 Mathematics 7 Petition 870260049536, dated 05 / 25 / 2026, page 16 / 77 12 / 28er . _F\S'h(^) 2π / ε0 2 \r0r°°) Cosh 0X+cos(^) - (1 0) Mathematics 8 X = 1η(ωτ) = 1η(2π / τ) ··· (1 1) εο: Dielectric constant of vacuum

[0051] Figures 7A and 7B compare the curve obtained through fitting to the improved Cole-Cole type theoretical formula and the experimentally obtained values. The experimental values ​​in Figures 7A and 7B are the same as those in Figures 4A and 4B, respectively. As shown in Figure 7A, regarding the relative dielectric constant, the theoretical formula can express the trend of the experimental values ​​through fitting, similar to the Cole-Cole type. Furthermore, with reference to Figure 7B, in addition to the relaxation time τ (peak position), regarding the trend of the relative dielectric loss factor in the low frequency range, the theoretical values ​​can express the trend of the experimental values ​​through fitting.

[0052] By performing the adjustment to the theoretical formula above, as the parameters of the electrical properties of grease 12, it is possible to derive the relative dielectric constant at the low frequency limit and at the high frequency limit, the relaxation resistance, the average dielectric constant, the relaxation time, the relaxation time distribution and the DC conductivity. Processing Flowchart

[0053] Figure 8 is a flowchart of the condition diagnostic processing according to the present embodiment. This processing is performed by the condition diagnostic device 30. For example, the control device (not shown) included in the condition diagnostic device 30 can be operated by reading a program from a storage device (not shown) to Petition 870260049536, dated 05 / 25 / 2026, page 17 / 77 13 / 28 perform the processing according to this method and run the program.

[0054] In S801, the condition diagnostic device 30 controls the measuring device 31 to apply AC voltage V with angular frequency ω to grease 12 using the AC power source 10 included in the measuring device 31. As a result, AC voltage V with angular frequency ω is applied to grease 12.

[0055] In S802, the condition diagnostic device 30 acquires the impedance |Z| and phase angle θ from the measuring device 31 as a result of the instructed input in S801. That is, the measuring device 31 sends the impedance |Z| and phase angle θ to the condition diagnostic device 30 as the measurement results of the grease 12 with respect to the input AC voltage V with the angular frequency ω.

[0056] In S803, the condition diagnostic device 30 derives the relative dielectric constant and relative dielectric loss factor corresponding to each frequency based on the impedance information |Z| and the phase angle θ obtained in S802, and the AC voltage information V with the angular frequency ω instructed in S801. A known method can be used for the derivation method in this document. Furthermore, the relative dielectric constant and the relative dielectric loss factor are derived by the measuring device 31, and the relative dielectric constant and the relative dielectric loss factor can be sent to the condition diagnostic device 30 as the measurement results together with the impedance |Z| and the phase angle θ.

[0057] In S804, the condition 30 diagnostic device adjusts the measurement result obtained to the theoretical formula described above. For example, the condition 30 diagnostic device performs the adjustment to the enhanced Cole-Cole type theoretical formulas shown in Petition 870260049536, dated 05 / 25 / 2026, page 18 / 77 14 / 28 Formulas (9) to (11).

[0058] In S805, the condition diagnostic device 30 derives several parameters from the result of the adjustment in S804. Note that it is not necessary to derive all seven parameters described above at the same time and, for example, only the necessary parameters can be derived according to the item that is a target to be diagnosed. The necessary parameters in this document can be configured in any way by the user performing the diagnosis. Furthermore, an example of the relationship between each parameter and diagnostic items will be described later.

[0059] In S806, the condition diagnostic device 30 diagnoses the condition of grease 12 based on each of the parameters derived in S805. Although the diagnostic content in this document is not particularly limited, for example, a threshold value can be defined for each parameter and normality or abnormality can be diagnosed by comparison with the threshold value. Alternatively, a plurality of threshold values ​​can be defined according to the degree of urgency of the abnormality, and the degree of urgency can be diagnosed by comparison with these threshold values.

[0060] In S807, the condition diagnostic device 30 notifies the user of the diagnostic result obtained in S806. Although the notification method in this document is not particularly limited, for example, the parameters or items determined as abnormal may be displayed on the screen or notified by voice. Then, this processing flowchart ends. Relationship Between Various Parameters and Lubricant Condition

[0061] The relationship between the various parameters derived from the method described above and the condition of the lubricant (grease 12 in this case) will be described below. Petition 870260049536, dated 05 / 25 / 2026, page 19 / 77 15 / 28 Relationship Between the Amount of Thickener and the Parameters

[0062] Figures 9A, 9B and 10 describe the relationship between the amount of thickener in grease 12 and the parameters. In this document, an example of grease with the following composition is shown. In addition, the amount of the three thickeners (proportion [%] in the grease) is shown as an example. Base oil: ester + mineral oil Thickener: 12OH (lithium 12-hydroxystearate grease: 12-OHStLi) (short fiber) Thickener quantity: 3%, 7.5%, 15%

[0063] In Figure 9A, the horizontal axis indicates the frequency [Hz] and the vertical axis indicates the relative dielectric constant eA. As shown in Figure 9A, the relative dielectric constant tends to decrease (decrease monotonically) as the frequency increases, regardless of the amount of thickener. This trend is similar to that described with reference to Figure 4A. On the other hand, the relative dielectric constant e^ in the low-frequency limit differs depending on the amount of thickener. Furthermore, the degree of variation in the relative dielectric constant with frequency variation differs depending on the amount of thickener. Conversely, in the high-frequency range, fluctuations in the amount of thickener have little effect on the relative dielectric constant.

[0064] Since grease 12 contains a thickener, an electric field opposing the external electric field applied to grease 12 is generated in the low-frequency region. As a result, in the low-frequency region, the dielectric constant (the relative dielectric constant er0 in the low-frequency limit) increases according to the amount of thickener. On the other hand, in the high-frequency region, an electric field opposing the external electric field applied to grease 12 is not generated. Therefore, in the high-frequency region, the dielectric constant (the Petition 870260049536, dated 05 / 25 / 2026, page 20 / 77 16 / 28 The relative dielectric constant Σr~ in the high-frequency limit) fluctuates little depending on the amount of thickener. For this reason, a difference occurs in the relative dielectric constant ε^ in the low-frequency limit according to variations in the amount of thickener, as shown in Figure 9A.

[0065] In Figure 9B, the horizontal axis indicates the frequency [Hz] and the vertical axis indicates the relative dielectric loss factor εΛ. As shown in Figure 9B, the relative dielectric loss factor ε / ' decreases as the frequency increases, then tends to increase and then decreases again. This trend is similar to that described with reference to Figure 4B.

[0066] Figure 10 summarizes the parameters derived from the values ​​shown in Figure 9. As shown in Figure 10, it can be seen that several parameters fluctuate as the amount of thickener fluctuates. In other words, it can be inferred that there is a correlation between the amount of thickener and the parameters that indicate the electrical properties. Therefore, the variation in the amount of thickener can be specified by referring to the parameters (in particular, the relative dielectric constant ε^ in the low frequency limit) derived in the present embodiment.

[0067] Figure 11 is a diagram to explain the relationship between the type of base oil, the amount of thickener, and the resistance to relaxation. In Figure 11, the horizontal axis indicates the amount of thickener (proportion in the grease) [%] and the vertical axis indicates the resistance to relaxation (ε^-ε^). Additionally, two types of base oils—mineral oil-based, ester-based, and ester / PAO-based—are shown as examples. As indicated by the straight line in Figure 11, regardless of the type of base oil, the resistance to relaxation increases as the amount of thickener increases. Therefore, regardless of the type of oil Petition 870260049536, dated 05 / 25 / 2026, page 21 / 77 17 / 28 base, the amount of thickener can be specified when referring to the resistance to relaxation. Relationship Between Thickener Fiber State and Parameters

[0068] Figures 12A to 14 describe the relationship between the thickener fiber state in grease 12 and the parameters.

[0069] Figure 12 is a diagram to explain the fiber state of the thickener contained in grease 12. In the present document, a grease containing a thickener whose fiber structure has been destroyed was produced by subjecting grease 12 to roller processing under the following conditions. Base oil: mineral oil Thickener: 12-OHStLi Roller pressure: 1 [MPa] Number of rollers: 5 times

[0070] Figure 12A shows an example of the condition before roller processing, where the fiber structure is maintained. Figure 12B shows an example of the condition after roller processing, where the fiber structure is destroyed. In Figures 12A and 12B, the scale unit is μm. Furthermore, the fiber state in this document is an example and is not limited to it.

[0071] In Figure 13A, the horizontal axis indicates the frequency [Hz] and the vertical axis indicates the relative dielectric constant eA. As shown in Figure 13A, the relative dielectric constant tends to decrease (decrease monotonically) as the frequency increases, regardless of the fiber state of the thickener. This trend is similar to that described with reference to Figure 4A. On the other hand, the relative dielectric constant e^ in the low-frequency limit differs depending on the fiber state of the thickener. Furthermore, the degree of variation in the relative dielectric constant with frequency variation differs depending on the fiber state of the thickener. On the other hand, in Petition 870260049536, dated 05 / 25 / 2026, page 22 / 77 In the 18 / 28 high-frequency band, fluctuations in the amount of thickener have little effect on the relative dielectric constant.

[0072] In Figure 13B, the horizontal axis indicates the frequency [Hz] and the vertical axis indicates the relative dielectric loss factor εΛ. As shown in Figure 13B, the relative dielectric loss factor increases as the frequency increases and then tends to decrease. This trend is similar to that described with reference to Figure 4B. In the low-frequency region, the difference due to the thickener fiber state is small, but there is a difference in the peak and distribution of the relative dielectric loss factor and in the peak position (relaxation time τ). For example, the constant β, which represents the relaxation time distribution, tends to decrease when the fiber structure is destroyed.

[0073] Figure 14 summarizes the parameters derived from the values ​​shown in Figures 13A and 13B. As shown in Figure 14, it can be seen that several parameters fluctuate as the fiber state of the thickener fluctuates. In other words, it can be inferred that there is a correlation between the fiber state of the thickener and the parameters that indicate the electrical properties. Therefore, by referring to the derived parameters in the present embodiment (especially the relaxation time and the constant that indicates the relaxation time distribution), it is possible to specify the variation in the fiber state of the thickener. Relationship Between Grease Deterioration and Parameters

[0074] Figures 15A to 17B describe the relationship between the deterioration (oxidative deterioration) of grease 12 and the parameters. Figures 15A to 16B are diagrams to explain the relationship between the frequency and degree of deterioration (oxidative deterioration, i.e., increased oxygen consumption) of the base oil that constitutes grease 12. Petition 870260049536, dated 05 / 25 / 2026, page 23 / 77 19 / 28

[0075] In Figure 15A, the horizontal axis indicates the frequency [Hz] and the vertical axis indicates the relative dielectric constant εA. As shown in Figure 15A, the relative dielectric constant is almost constant, regardless of variations in frequency. Furthermore, the relative dielectric constant increases as oxygen consumption increases.

[0076] In Figure 15B, the horizontal axis indicates oxygen consumption [%] and the vertical axis indicates the average dielectric constant εA. As shown in Figure 15B, the average dielectric constant increases as oxygen consumption increases.

[0077] The average dielectric constant increases as the polarity of the molecules in the base oil increases. The base oil is conventionally nonpolar (e.g., in a new condition), but becomes more polar due to oxidative deterioration. Therefore, the average dielectric constant increases due to the oxidative deterioration of the base oil.

[0078] In Figure 16A, the horizontal axis indicates the frequency [Hz] and the vertical axis indicates the relative dielectric loss factor εA. As shown in Figure 16A, the relative dielectric loss factor in the low frequency range increases as oxygen consumption increases.

[0079] In Figure 16B, the horizontal axis indicates oxygen consumption [%] and the vertical axis indicates DC conductivity σ0. As shown in Figure 16B, DC conductivity increases as oxygen consumption increases.

[0080] From the above, it can be inferred that there is a correlation between the deteriorated condition of the base oil that constitutes grease 12 and the parameters that indicate the electrical properties. Therefore, the degree of deterioration of the base oil can be specified by referring to variations in several parameters (in particular, the Petition 870260049536, dated 05 / 25 / 2026, p. 24 / 77 20 / 28 average dielectric constant and DC conductivity) derived in this embodiment.

[0081] Figures 17A and 17B are diagrams to explain the relationship between frequency and relative dielectric constant and the relative dielectric loss factor due to grease deterioration. In this document, the results of a comparison between new and deteriorated grease using an oxidation stability tester are shown. In Figure 17A, the horizontal axis indicates the frequency [Hz] and the vertical axis indicates the relative dielectric constant εA. The relative dielectric constant of both new and deteriorated grease tends to decrease as the frequency increases. This trend is similar to that described with reference to Figure 4A. On the other hand, when comparing the average dielectric constants, the deteriorated grease showed a higher value. In this document, the average dielectric constant of the new grease was 3.6 and the average dielectric constant of the deteriorated grease was 3.8.

[0082] In Figure 17B, the horizontal axis indicates the frequency [Hz] and the vertical axis indicates the relative dielectric loss factor. In this case, when compared with the DC conductivity qo, the deteriorated grease showed a higher value. In the present document, the DC conductivity of the new grease was 1.4 and the DC conductivity of the deteriorated grease was 42.

[0083] From the above, it can be inferred that there is a correlation between the deteriorated state of grease 12 and the parameters that indicate the electrical properties. Therefore, the degree of deterioration of grease 12 can be specified by referring to variations in several parameters (in particular, the average dielectric constant and the DC conductivity) derived in the present embodiment. Relationship Between Water Content and Parameters

[0084] In Figures 18A to 19B, the relationship between the water content in grease 12 and the parameters will be described. Figures 18A and 18B are a Petition 870260049536, dated 05 / 25 / 2026, p. 25 / 77 Figure 21 / 28 explains the relationship between the water content in grease 12 and the relative dielectric constant Er' and the relative dielectric loss factor Er''. In this document, an example will be described in which the measurement is performed while grease 12 contains 0 to 10% moisture, the voltage is 1.0 V, and the frequency is in the range of 30 Hz to 1 MHz.

[0085] In Figure 18A, the horizontal axis indicates the logarithm of the frequency [Hz] and the vertical axis indicates the relative dielectric constant Er'. As shown in Figure 18A, the relative dielectric constant Er' tends to show a substantially constant value, depending on the water content, regardless of variations in frequency. Furthermore, the relative dielectric constant Er' tends to show a higher value as the water content in grease 12 increases.

[0086] In Figure 18B, the horizontal axis indicates the logarithm of the frequency [Hz] and the vertical axis indicates the relative dielectric loss factor Er''. As shown in Figure 18B, even when the water content in grease 12 increases, there is no significant difference in the variation trend of the relative dielectric loss factor. In other words, regardless of the water content, the variation trend of the relative dielectric loss factor Er'' when the frequency fluctuates is almost the same.

[0087] Figures 19A and 19B are a diagram to explain the relationship between the water content in grease 12 and the average dielectric constant Er'-. In Figures 19A and 19B, the horizontal axis indicates the water content [% by weight] in grease 12 and the vertical axis indicates the average dielectric constant Er'-. In the present document, grease 12 is completely mixed with water. As shown in Figures 19A and 19B, the average dielectric constant Er'- tends to increase (increase monotonically) as the water content increases.

[0088] From the above, it can be inferred that there is a correlation between the water content in grease 12 and the parameters that Petition 870260049536, dated 05 / 25 / 2026, p. 26 / 77 22 / 28 indicate the electrical properties, specifically the correlation between the relative dielectric constant Er' and the average dielectric constant Er'-. Therefore, by paying attention to these parameters, it is possible to specify the contamination of grease 12 with moisture. The deterioration of grease 12 was described with reference to Figures 15A to 17B; however, the trend of variation of the parameters at this point (e.g., the average dielectric constant Er'- of Figure 15B and the DC conductivity σ0 of Figure 16B) and the trend of variation of the parameters shown in Figures 18A and 18B or Figures 19A and 19B are different. Therefore, by capturing the difference in these variations, it is possible to separately detect the deterioration of the grease and the contamination of the grease with water. Relationship Between the Amount of Iron Powder and the Parameters

[0089] Figure 20 describes the relationship between the amount of iron powder in grease 12 and the parameters. Figure 20 is a diagram to explain the relationship between the amount of iron powder in grease 12 and the relative dielectric loss factor Er''. Due to the presence of iron powder in grease 12, the DC conductivity σ0 increases extremely. While the variation in DC conductivity due to other factors is on a scale of approximately 10 to 100 times, the increase in DC conductivity due to contamination (increase) of iron powder shows a variation of 10⁶ or more. In this document, the detection is performed focusing on the variation. In this document, an example will be described in which the measurement is performed while grease 12 contains 0 to 20% moisture, the voltage is 1.0 V, and the frequency is in the range of 30 Hz to 1 MHz.

[0090] In Figure 20, the horizontal axis indicates the logarithm of the frequency [Hz] and the vertical axis indicates the relative dielectric loss factor Er. In this document, four examples are shown in which the amount of iron powder contained in grease 12 (weight ratio for the grease) is 0%, 10%, 15%, and 20%. When the amount of iron powder Petition 870260049536, dated 05 / 25 / 2026, page 27 / 77 23 / 28 is 0%, 10%, 15%, and 20%, the DC conductivity σo is 2.0 χ 10-108, 5.4 χ 10-38, 1.9 χ 10-2S, and 2.0 χ 10S. That is, the value of DC conductivity σo is extremely different depending on the amount of iron powder in grease 12. Therefore, by evaluating the value of DC conductivity σo, it is possible to measure the amount of iron powder in grease 12, that is, the contamination by iron powder. Summary

[0091] In this embodiment, the parameters related to dielectric relaxation are derived as electrical properties to specify the condition of a lubricant (grease in this example). Each parameter can be used to specify the condition of the lubricant as follows.

[0092] Relative dielectric constant (e^) in the low frequency limit: amount of thickener

[0093] Relative dielectric constant (ε^) in the high frequency limit: type of base oil

[0094] Resistance to relaxation (ε^-ε^): amount of thickener

[0095] Average dielectric constant (ε / -): degree of deterioration of the base oil, water content in the grease

[0096] Relaxation time (τ): thickener fiber state, degree of grease deterioration

[0097] Constant (β) indicating the relaxation time distribution: thickener fiber state, degree of grease deterioration

[0098] DC Conductivity (σ0): amount of thickener, degree of deterioration of the base oil, degree of deterioration of the grease, amount of additives, amount of iron powder in the grease

[0099] Note that the correlation between each parameter and the condition of the lubricant is an example and is not limited to the above. For example, a Petition 870260049536, dated 05 / 25 / 2026, page 28 / 77 A 24 / 28 condition item can be diagnosed from a plurality of parameters, or a plurality of condition items can be diagnosed from a single parameter. Furthermore, the condition can be diagnosed after specifying the correlation between the parameters and the condition according to the lubricant's composition.

[00100] As described above, according to the present embodiment, it is possible to specify the parameters that indicate the electrical properties of the lubricant without destroying the target to be diagnosed. Thus, it is possible to easily diagnose the condition of the lubricant based on the parameters that indicate its electrical properties. Other Modalities

[00101] Furthermore, in the present invention, a program or application for performing the functions of one or more embodiments described above is provided to a system or device using a network or storage medium and can be operated by processing performed as one or more processors in the computer of the system or device when reading the program.

[00102] In addition, the circuit that performs one or more functions can be implemented as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

[00103] As described above, the present invention is not limited to the embodiments described above; it is also possible for those skilled in the art to combine each configuration of the embodiments with each other, modify and apply them based on the description in the descriptive report and well-known technology, and the combinations, modifications and applications are within the scope for which protection is sought.

[00104] As described above, this descriptive report Petition 870260049536, dated 05 / 25 / 2026, page 29 / 77 25 / 28 describes the following topics.

[00105] (1) A condition diagnostic method comprising: a step of measuring the relative dielectric constant of a lubricant by applying a voltage to the lubricant while varying the frequency of an AC power source; a step of deriving parameters that indicate electrical properties of the lubricant by applying the relative dielectric constant measured in the measurement step to a theoretical formula; and a diagnostic step to diagnose a condition of the lubricant using the parameters.

[00106] According to this configuration, it is possible to easily diagnose the condition of a lubricant without destroying the target being diagnosed.

[00107] (2) The condition diagnosis method according to (1), wherein the parameters include at least one of the relative dielectric constant at the low frequency limit, relative dielectric constant at the high frequency limit, relaxation resistance, average dielectric constant, relaxation time, relaxation time distribution and DC conductivity.

[00108] According to this configuration, it is possible to derive a plurality of parameters to diagnose the condition of the lubricant.

[00109] (3) The condition diagnosis method according to (1) or (2), wherein the theoretical formulas are expressed by: Mathematics 9 Mathematics 10 I' ' _ σ01 / _ λsinh(v)r2π / ε02 \r0r°°) coshpx+cos(^^ Mathematics 11 Petition 870260049536, dated 05 / 25 / 2026, page 30 / 77 26 / 28

[00110] According to this configuration, it is possible to derive the theoretical values ​​of the relative dielectric constant and the relative dielectric loss factor with greater precision.

[00111] (4) The condition diagnosis method according to any one of (1) to (3), in which the lubricant is in the bulk state.

[00112] According to this configuration, it is possible to diagnose the condition of the lubricant in the bulk state.

[00113] (5) The condition diagnosis method according to any one of (1) to (4), wherein the lubricant is lubricating oil.

[00114] According to this configuration, it is possible to consider the lubricating oil as a target to be diagnosed.

[00115] (6) The condition diagnosis method according to any one of (1) to (4), wherein the lubricant is grease.

[00116] According to this configuration, grease can be considered a target to be diagnosed.

[00117] (7) The condition diagnosis method according to (6) wherein, in the diagnosis step, at least one of the thickener quantity, thickener fiber state, grease deterioration degree, grease water content and grease iron powder quantity is diagnosed as a grease condition.

[00118] According to this configuration, it is possible to diagnose a plurality of grease conditions.

[00119] (8) A condition diagnostic device which includes: a measuring unit for measuring the relative dielectric constant of a lubricant by applying a voltage to the lubricant while varying the frequency of an AC power source; a derivation unit for deriving parameters that indicate electrical properties of the lubricant by applying the relative dielectric constant measured in the measuring unit to a theoretical formula; and a diagnostic unit for Petition 870260049536, dated 05 / 25 / 2026, page 31 / 77 27 / 28 diagnose a lubricant condition using the parameters.

[00120] According to this configuration, it is possible to easily diagnose the condition of a lubricant without destroying the target being diagnosed.

[00121] (9) A program for making a computer perform a measurement step to measure the relative dielectric constant of a lubricant by applying a voltage to the lubricant while varying the frequency of an AC power source, a derivation step to derive parameters that indicate the electrical properties of the lubricant by applying the relative dielectric constant measured in the measurement step to a theoretical formula, and a diagnostic step to diagnose a condition of the lubricant using the parameters.

[00122] According to this configuration, it is possible to easily diagnose the condition of a lubricant without destroying the target being diagnosed.

[00123] Although various embodiments have been described above with reference to the drawings, it is needless to say that the present invention is not limited to such examples. In the case of those skilled in the art, it is evident that various examples of modification or examples of correction may be assumed within the scope described in the claims, and it will be understood that the examples of modification or examples of correction belong to the technical scope of the present invention. Furthermore, each component in the above embodiments may be combined in any manner without departing from the essence of the invention.

[00124] This application is based on a Japanese Patent Application filed on September 29, 2020 (Japanese Patent Application 2020-163961) and a Japanese Patent Application filed on August 25, 2021 (Japanese Patent Application 2021-137562), the content of which is incorporated by reference into this application. Petition 870260049536, dated 05 / 25 / 2026, p. 32 / 77 28 / 28 LIST OF REFERENCE SIGNS AC power supply ... Electrode ... Grease ... Condition diagnostic device ... Measuring device ... Inclusion of material Petition 870260049536, dated 05 / 25 / 2026, page 33 / 77

Claims

1 / 3 CLAIMS 1. A condition diagnostic method comprising: a measurement step for measuring the relative dielectric constant of a lubricant by applying a voltage to the lubricant while varying the frequency of an AC power source; a parameter derivation step indicating electrical properties of the lubricant by applying the relative dielectric constant measured in the measurement step to a theoretical formula; and a diagnostic step for diagnosing a lubricant condition using the parameters, characterized in that the parameters include at least one of the relative dielectric constant at the low frequency limit, relative dielectric constant at the high frequency limit, relaxation resistance, average dielectric constant, relaxation time, relaxation time distribution, and DC conductivity.

2. Condition diagnostic method, according to claim 1, characterized in that the theoretical formulas are expressed by: Mathematics 1 Mathematics 2 ; and Mathematics 3 where ω: angular frequency of the voltage; Petition 870260049536, dated 05 / 25 / 2026, page 34 / 77 2 / 3 £ro: relative dielectric constant at low frequency limit; £r~: relative dielectric constant at high frequency limit; £r0-er~: Relaxation resistance; ε / -: Average dielectric constant; τ: Relaxation time [s]; β: Constant indicating the relaxation time distribution; and σ0: DC conductivity [S / m].

3. Condition diagnostic method according to claim 1 or 2, characterized in that the lubricant is in a bulk state.

4. A method for diagnosing a condition, according to any one of claims 1 to 3, characterized in that the lubricant is lubricating oil.

5. A method for diagnosing a condition, according to any one of claims 1 to 3, characterized in that the lubricant is grease.

6. Condition diagnosis method, according to claim 5, characterized in that, in the diagnosis step, at least one of the following: the amount of thickener, the thickener fiber state, the degree of grease deterioration, the water content in the grease, and the amount of iron powder in the grease is diagnosed as a grease condition.

7. Condition diagnostic device, characterized in that it comprises: a measuring unit for measuring the relative dielectric constant of a lubricant by applying a voltage to the lubricant while varying the frequency of an AC power source; a derivation unit for deriving parameters that indicate electrical properties of the lubricant by applying the relative dielectric constant measured by the measuring unit to a theoretical formula, wherein the parameters include at least one of the relative dielectric constant at the low frequency limit, relative dielectric constant at the high frequency limit, relaxation resistance, average dielectric constant, relaxation time, relaxation time distribution and DC conductivity; and a diagnostic unit for diagnosing a condition of the lubricant using the parameters.

8. Non-transient computer-readable storage medium characterized in that it has instructions encoded therein which, when executed by a processor, cause the processor to execute the following process when employing the condition diagnostic device as defined in claim 7, the process comprising: a measurement step to measure the relative dielectric constant of a lubricant by applying a voltage to the lubricant while varying the frequency of an AC power source;a parameter derivation step that indicates the electrical properties of the lubricant by applying the relative dielectric constant measured in the measurement step to a theoretical formula, wherein the parameters include at least one of the following: relative dielectric constant at the low frequency limit, relative dielectric constant at the high frequency limit, relaxation resistance, average dielectric constant, relaxation time, relaxation time distribution, and DC conductivity; and a diagnostic step to diagnose a lubricant condition using the parameters. Petition 870260049536, dated 05 / 25 / 2026, p. 36 / 77;

Images