Oil film temperature deriving method, temperature deriving device, and program

Abstract

A method for easily deriving the oil film temperature of a lubricant in a device is provided. [Solution] A temperature derivation method for deriving the oil film temperature of a lubricant in a device, comprising a measurement step of measuring the dielectric constant of the lubricant by applying an AC voltage while changing the frequency to an electrical circuit formed by a bearing device 2 using an LCR meter 8, a derivation step of applying the dielectric constant measured in the measurement step to a theoretical formula to derive the relaxation time of the lubricant, and a calculation step of calculating the oil film temperature using the relaxation time.

Description

[Technical Field]

[0001] The present invention relates to a method for deriving the temperature of an oil film, a temperature deriving device, and a program. [Background technology]

[0002] Conventionally, bearing devices have been widely configured to use lubricants (e.g., lubricating oil or grease) to lubricate their rotation. Meanwhile, rotating parts such as bearing devices are routinely diagnosed for their condition to detect damage or wear at an early stage and prevent failure of the rotating parts.

[0003] In bearing devices that use lubricants, it is necessary to properly detect the state of the lubricant in order to diagnose the operating state. For example, Patent Document 1 discloses a method for detecting the thickness of the lubricant film and the metal contact ratio in a rolling device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-211317 Summary of the Invention [Problem to be solved by the invention]

[0005] Understanding the conditions around the lubricant in devices such as bearings is extremely useful for preventing damage to the device. Examples of conditions around the lubricant include the temperature of the lubricant oil film. The method of Patent Document 1 can derive the thickness of the lubricant film and the metal contact ratio, but does not measure the temperature of the lubricant. When measuring the temperature of the lubricant oil film, which is expected to change in temperature, constraints arise due to the installation location of the temperature sensor and the control of measurement based on the temperature sensor's measurement principle. For example, methods using infrared rays such as thermography require the object's thermal radiation to be constant. Furthermore, temperature diagnosis methods using layers such as thermochromism require the object to be located in a location where it can be diagnosed.

[0006] In view of the above problems, an object of the present invention is to provide a method for easily deriving the oil film temperature of the lubricant in the device. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following configuration: That is, a temperature deriving method for deriving an oil film temperature of a lubricant in an apparatus, comprising: a measuring step of measuring the dielectric constant of the lubricant by applying an AC voltage while changing the frequency to an electric circuit constituted by the device; a derivation step of applying the dielectric constant measured in the measurement step to a theoretical formula to derive a relaxation time of the lubricant; a calculation step of calculating the oil film temperature using the relaxation time; It has.

[0008] Another aspect of the present invention has the following configuration: A temperature deriving device for detecting an oil film temperature of a lubricant in a device, comprising: a measuring means for measuring the dielectric constant of the lubricant by applying an AC voltage to an electric circuit constituted by the device while changing the frequency; a derivation means for applying the dielectric constant measured by the measurement means to a theoretical formula to derive a relaxation time of the lubricant; a calculation means for calculating the oil film temperature using the relaxation time; It has.

[0009] Another aspect of the present invention has the following configuration: a program comprising: On the computer, a measuring step of measuring the dielectric constant of the lubricant in the device by applying an AC voltage while changing the frequency to an electric circuit constituted by the device; a derivation step of applying the dielectric constant measured in the measurement step to a theoretical formula to derive a relaxation time of the lubricant; a calculation step of calculating an oil film temperature of the lubricant using the relaxation time; Execute the following. [Effects of the Invention]

[0010] The present invention makes it possible to provide a method for easily deriving the oil film temperature of the lubricant in the device. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing an example of an apparatus configuration according to an embodiment of the present invention. [Figure 2] FIG. 10 is a diagram for explaining the relationship between frequency and dielectric constant. [Figure 3] FIG. 1 is a diagram for explaining the relationship between relaxation time and absolute temperature. [Figure 4] FIG. 10 is a diagram for explaining derivation of parameters by fitting to a theoretical formula. [Figure 5] FIG. 1 is a diagram for explaining the correlation between temperature and relaxation time. [Figure 6] FIG. 4 is a diagram showing an example of a result of deriving an oil film temperature according to the present embodiment. [Figure 7] 4 is a flowchart of a process for deriving a temperature according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Note that the embodiment described below is one embodiment for explaining the present invention and is not intended to be interpreted as limiting the present invention. Furthermore, not all of the configurations described in each embodiment are necessarily essential configurations for solving the problems of the present invention. Furthermore, in each drawing, the same components are assigned the same reference numerals to indicate correspondence.

[0013] First Embodiment A first embodiment of the present invention will be described below. In the following description, a ball bearing will be used as an example of a rolling bearing, but the present invention is not limited to this and can be applied to rolling bearings of other configurations. For example, types of rolling bearings to which the present invention can be applied include deep groove ball bearings, angular contact ball bearings, tapered roller bearings, cylindrical roller bearings, and self-aligning roller bearings.

[0014] [Device configuration] FIG. 1 is a schematic diagram showing an example of the overall configuration when diagnosis is performed by a diagnostic device 1 according to this embodiment. FIG. 1 shows a bearing device 2 to which the temperature derivation method according to this embodiment is applied, and a diagnostic device 1 that derives and diagnoses the temperature of an oil film. Note that the configuration shown in FIG. 1 is just one example, and a different configuration may be used depending on the configuration of the bearing device 2, etc. Also, while FIG. 1 shows a configuration in which the bearing device 2 includes one rolling bearing, this is not limiting, and one bearing device 2 may include multiple rolling bearings.

[0015] In the bearing device 2, a rolling bearing rotatably supports a rotating shaft 7. The rotating shaft 7 is supported by a housing (not shown) that covers the outside of the rotating shaft 7 via a rolling bearing, which is a rotating component. The rolling bearing includes an outer ring (outer member) 3, which is a fixed ring fitted inside the housing; an inner ring (inner member) 4, which is a rotating ring fitted around the rotating shaft 7; a plurality of balls (rollers), which are a plurality of rolling elements 5, arranged between the inner ring 4 and the outer ring 3; and a cage (not shown) that rotatably holds the rolling elements 5. Here, the outer ring 3 is configured to be fixed, but the inner ring 4 may be configured to be fixed and the outer ring 3 to rotate. In addition, a seal 6, which is a peripheral component, is provided to prevent the intrusion of dust around the rolling elements 5 and the leakage of lubricating oil. A predetermined lubrication method is used inside the rolling bearing to reduce friction between the inner ring 4 and the rolling elements 5 and between the outer ring 3 and the rolling elements 5. The lubrication method is not particularly limited, but for example, grease lubrication or oil lubrication is used and supplied to the inside of the rolling bearing. The type of lubricant is also not particularly limited.

[0016] The motor 10 is a driving motor that supplies rotational power to the rotating shaft 7. The rotating shaft 7 is connected to an LCR meter 8 via a rotary connector 9. The rotary connector 9 may be configured using, for example, but is not limited to, a carbon brush. The bearing device 2 is also electrically connected to the LCR meter 8, and in this case, the LCR meter 8 also functions as an AC power source for the bearing device 2.

[0017] The diagnostic device 1 operates as a temperature derivation device capable of executing the temperature derivation method according to this embodiment. During diagnosis, the diagnostic device 1 instructs the LCR meter 8 to input the angular frequency ω of the AC power supply and the AC voltage V, and acquires the impedance |Z| (|Z| indicates the absolute value of Z) and phase angle θ of the bearing device 2 from the LCR meter 8 as outputs in response. The diagnostic device 1 then uses these values ​​to derive the temperature of the oil film of the lubricant in the bearing device 2. The oil film here corresponds to, for example, a film made of lubricant that has flowed between the outer ring 3 and the rolling elements 5, or between the inner ring 4 and the rolling elements 5. The method of deriving the oil film temperature will be described in detail later.

[0018] The diagnostic device 1 may be realized, for example, by an information processing device including a control device, a storage device, and an output device (not shown). The control device may be configured with a central processing unit (CPU), a microprocessing unit (MPU), a digital single processor (DSP), or a dedicated circuit. The storage device is configured with volatile and nonvolatile storage media such as a hard disk drive (HDD), a read-only memory (ROM), or a random access memory (RAM), and is capable of inputting and outputting various information in response to instructions from the control device. The output device is configured with a speaker, a light, or a display device such as an LCD display, and notifies the operator in response to instructions from the control device. The notification method used by the output device is not particularly limited, and may be, for example, an auditory notification using voice or a visual notification using a screen output. The output device may also be a network interface with a communication function, and may perform the notification operation by transmitting data to an external device (not shown) via a network (not shown). The notification content here is not limited to a notification when an abnormality is detected, for example, when an abnormality diagnosis is performed based on the derived results of the oil film temperature, but may also include a notification that the bearing device 2 is normal.

[0019] As shown in Fig. 1, the bearing device 2 is configured to include multiple parts. With this configuration, the bearing device 2 can be considered as an electric circuit. Then, by applying an AC voltage to this electric circuit from an AC power supply (not shown) provided in an LCR meter 8, the electrical characteristics of the bearing device 2 can be measured. The AC voltage V applied to the electric circuit of the bearing device 2, the current I flowing through the electric circuit, and the complex impedance Z of the entire electric circuit are expressed by the following equations (1) to (3). V = |V|exp(jωt) …(1) I = |I|exp(jωt-jθ) …(2) Z=V / I=|V / I|exp(jθ)=|Z|exp(jθ) …(3) j: imaginary number ω: Angular frequency of AC voltage t: time θ: Phase angle (phase difference between voltage and current)

[0020] By applying an AC voltage using the LCR meter 8, the impedance |Z| (|Z| indicates the absolute value of Z) and phase angle θ of the bearing device 2 can be obtained. This information is used to detect the dielectric relaxation phenomenon of the lubricant in the bearing device 2. Note that the electrical circuit configured in the bearing device 2 differs depending on the structure of the bearing device 2. Therefore, a detailed explanation will be omitted here, but the following processing is assumed to be performed assuming an electrical circuit according to the structure of the bearing device 2.

[0021] [Dielectric constant and dielectric loss factor] 2 is a diagram for explaining the tendency of change in permittivity (relative permittivity and relative dielectric loss factor) according to change in frequency. In this example, in the configuration shown in FIG. 1, a test was conducted under the following conditions to measure the relative permittivity ε r The dielectric relaxation phenomenon caused by the lubricant in the rolling bearing was confirmed by measuring the dielectric loss factor εr" and the dielectric loss factor εr". Here, measurements were taken with the outer ring temperature at 23°C. As a comparison to the oil film caused by the lubricant inside the rolling bearing, the measurement results for lubricant (in bulk state) at a temperature of 23°C are also shown. Note that the lubricants are the same in all cases, and the temperature of the lubricant in bulk state does not change during measurement.

[0022] (Test conditions) Bearing: Deep groove ball bearing (product number: 6306) Rotation speed: 997 min -1 ] Axial load: 1000 [N] Radial load: 0 [N] Temperature: 23[℃] Lubricant: Lithium-based grease AC voltage: 1.0 [V] AC power frequency: 20 to 1 MHz [Hz]

[0023] In Figure 2(a), the horizontal axis shows the logarithm of frequency [Hz], and the vertical axis shows the relative permittivity εr'. Figure 2(a) shows the experimental values ​​obtained from the above test results for the oil film of lubricant in the rolling bearing and the lubricant in bulk state. As shown in Figure 2(a), in both measurement results, the relative permittivity εr' decreases as the frequency increases. r ' has a tendency to decrease (monotonically decrease).

[0024] In Figure 2(b), the horizontal axis shows the logarithm of frequency [Hz], and the vertical axis shows the dielectric loss factor εr". Figure 2(b) shows the experimental values ​​obtained from the above test results for the oil film of lubricant in the rolling bearing and the lubricant in bulk state. As shown in Figure 2(b), in both measurement results, the dielectric loss factor εr" r " tends to decrease once as the frequency increases, then increase, and then decrease again.

[0025] Referring to Figure 2, there is a difference between the measurement results of the lubricant (bulk state) and the oil film of the lubricant inside the rolling bearing. As shown in Figure 2(b), the relaxation time τ (peak position) of the measurement results of the oil film of the lubricant inside the rolling bearing has shifted to the higher frequency side. Also, the measurement results of the oil film of the lubricant inside the rolling bearing show a higher DC conductivity σ0. The reason for this difference is that the temperature of the oil film inside the rolling bearing has risen above the outer ring temperature (23°C in this case) due to the rotation of the rolling bearing.

[0026] In this embodiment, the temperature of the oil film formed by the lubricant in the rolling bearing is derived based on the correlation between the relaxation time and the temperature of the oil film formed by the lubricant in the rolling bearing. FIG. 3 is a diagram for explaining the relationship between the relaxation time τ and the absolute temperature T. In FIG. 3, the vertical axis represents the relaxation time τ [μs], and the horizontal axis represents the absolute temperature T [K]. Here, an example of the measurement results for the lithium-based grease used in the test is shown. As shown in FIG. 3, as the relaxation time τ decreases, the absolute temperature T increases. Referring to FIG. 3, it can be seen that there is a correlation between the relaxation time τ and the absolute temperature T.

[0027] First, the relaxation time τ can be defined as the following equation (4) based on the Eyring equation.

[0028]

number

[0029] τ: relaxation time [s] K: equilibrium constant h: Planck's constant R: gas constant k B :Boltzmann constant T: absolute temperature ΔH ‡ : Activation enthalpy ΔS ‡ :Activation entropy ΔG ‡ : Gibbs energy of activation (= ΔH ‡ -TΔS ‡ ) exp: exponential function

[0030] Then, when the above formula (4) is rearranged for absolute temperature T using the Lambert W function, it can be defined as the following formula (5).

[0031]

number

[0032] W: Lambert W function

[0033] In this embodiment, the temperature of the oil film of the lubricant in the rolling bearing under axial load is calculated using the above equation (5). The equilibrium constant K, Planck's constant h, gas constant R, and Boltzmann's constant k B is set in advance. Also, the activation enthalpy ΔH ‡ and activation entropy ΔS ‡ The value of the activation enthalpy ΔH is measured in advance for the lubricant in a bulk state. ‡ and activation entropy ΔS ‡The value of can be derived by applying the actual measured value using the following equation (6).

[0034]

number

[0035] ln: logarithmic function

[0036] As an example of the lithium-based grease used in the above test, 12-OH Li-stearate grease is used as the lubricant. In this case, using the above formula (6), the activation enthalpy ΔH for the bulk lubricant can be calculated from the relationship between the relaxation time τ and the absolute temperature T. ‡ and activation entropy ΔS ‡ As a result, the following values ​​were obtained: ΔH ‡ =39.5 [kJ·mol -1 ] ΔS ‡ =-2.5 [J·mol -1 ·K -1 ]

[0037] [Applying to the theoretical formula] Next, the derivation of parameters relating to the dielectric relaxation phenomenon caused by the lubricant in the rolling bearing will be explained. The electrical characteristics based on the dielectric relaxation phenomenon of the lubricant in the rolling bearing have a change tendency as shown in FIG. 2. In order to identify the electrical characteristics with this change tendency, actual measured values ​​are applied (fitted) to a theoretical formula to derive various parameters. In this embodiment, the relaxation time τ is specified in order to derive the temperature of the oil film of the lubricant in the rolling bearing. In this embodiment, the theoretical formulas shown in the following equations (7) to (9) are used.

[0038]

number

[0039]

number

[0040]

number

[0041] ε r0 : Relative permittivity at the low frequency limit ε r∞ : Relative permittivity at high frequency limit τ: relaxation time [s] β: constant representing the distribution of relaxation times σ0: DC conductivity [S / m] ε0: Dielectric constant of vacuum π: Pi f: frequency

[0042] FIG. 4 compares the curve obtained by fitting the theoretical formula above with the experimental values ​​obtained using the configuration shown in FIG. 1. Here, the dielectric loss factor ε for specifying the relaxation time τ, which is the subject of this embodiment, is r In FIG. 4, the horizontal axis represents the logarithm of frequency [Hz], and the vertical axis represents the relative dielectric loss factor ε r As shown in Fig. 4, the theoretical values ​​for the dielectric loss factor are able to express the tendency of the experimental values ​​through fitting.

[0043] By applying the above theoretical formula, it is possible to derive the relaxation time τ, which is a parameter for the electrical properties of the lubricant. In the example shown in Figure 4, the relaxation time τ is derived as 1.2 [μs]. Then, by substituting this value into the above formula (5), the absolute temperature T [K] can be calculated. As a result, 46.3 [°C] is derived as the temperature of the lubricant oil film inside the rolling bearing.

[0044] The theoretical formulas shown in formulas (7) to (9) are based on the Cole-Cole type theoretical formula and are merely examples. Therefore, the present invention is not limited to these theoretical formulas, and other theoretical formulas may also be used.

[0045] [Verification example] Fig. 5 shows the results of measuring the dielectric loss factor by frequency sweeping in the temperature rise over time of the outer ring of a rolling bearing using the configuration shown in Fig. 1. In Fig. 5, the vertical axis represents the dielectric loss factor ε r ", and the horizontal axis shows the logarithm of frequency [Hz]. Here, four outer ring temperatures will be used for explanation: 23°C, 25°C, 27°C, and 29°C. As shown in Figure 5, as the outer ring temperature increases, the relaxation time τ (peak position) moves toward higher frequencies. In other words, it can be seen that there is a correlation between temperature and relaxation time.

[0046] FIG. 6 is a diagram showing the correspondence between the oil film temperature calculated using the relaxation time τ derived from the measurement results in FIG. 5 and equation (5), and the outer ring temperature. Referring to FIG. 6, the oil film temperature of the lubricant in the rolling bearing increases as the relaxation time τ decreases. Furthermore, all of these calculated values ​​are higher than the actually measured temperature of the outer ring. In other words, as shown in FIG. 6, the temperature derivation method according to this embodiment can derive the temperature of the lubricant itself, rather than the outer ring.

[0047] In the above test example, the inner ring was used as the rotating ring under a constant speed and a constant load. Similarly, the method according to this embodiment can be applied to a configuration in which the outer ring is used as the rotating ring.

[0048] [Processing flow] 7 is a flowchart of the temperature detection process according to this embodiment. This process is executed by the diagnostic device 1, and may be realized, for example, by a control device (not shown) included in the diagnostic device 1 reading out a program for implementing the process according to this embodiment from a storage device (not shown) and executing the program.

[0049] In S701, the diagnostic device 1 controls the bearing device 2 so that an axial load is applied in a predetermined load direction. Note that the control for applying the axial load may be performed by a device separate from the diagnostic device 1. At this time, the phase and impedance in a static contact state are measured.

[0050] In S702, the diagnostic device 1 starts the rotation of the rotating shaft 7 by the motor 10. This starts the rotation of the inner ring 4 connected to the rotating shaft 7. Note that the control of the motor 10 may be performed by a device separate from the diagnostic device 1.

[0051] In S703, the diagnostic device 1 controls the LCR meter 8 to apply an AC voltage V of angular frequency ω to the bearing device 2 using an AC power supply (not shown) provided in the LCR meter 8. As a result, the AC voltage V of angular frequency ω is applied to the bearing device 2.

[0052] In S704, the diagnostic device 1 acquires the impedance |Z| and the phase angle θ from the LCR meter 8 as outputs in response to the input in S703. That is, the LCR meter 8 outputs the impedance |Z| and the phase angle θ to the diagnostic device 1 as the detection results of the bearing device 2 in response to the input AC voltage V and the angular frequency ω of the AC voltage.

[0053] In S705, the diagnostic device 1 reads out various parameters for deriving the oil film temperature from the storage unit. Specifically, the diagnostic device 1 acquires parameters used in equation (5) corresponding to the lubricant used in the rolling bearing. These parameters are assumed to be defined in advance and stored in a storage device (not shown) or the like.

[0054] In S706, the diagnostic device 1 derives the dielectric constant and dielectric loss factor corresponding to each frequency based on the impedance |Z| and phase angle θ acquired in S704 and the AC voltage V at the angular frequency ω instructed in S703. A known method may be used for this derivation. Alternatively, the LCR meter 8 may derive the dielectric constant and dielectric loss factor, and output the dielectric constant and dielectric loss factor as measurement results to the diagnostic device 1 together with the impedance |Z| and phase angle θ.

[0055] In S707, the diagnostic device 1 applies (fits) the obtained measurement results to the theoretical formulas shown in the above formulas (7) to (9).

[0056] In S708, the diagnostic apparatus 1 derives the relaxation time τ from the result of the fitting in S707. A known method may be used to derive the relaxation time τ here.

[0057] In S709, the diagnostic device 1 derives the oil film temperature based on the relaxation time τ derived in S708 and the various parameters acquired in S705. Specifically, the diagnostic device 1 calculates the absolute temperature T by substituting the various parameters into the above formula (2), and converts it into the oil film temperature (Celsius temperature). Note that the oil film temperature may be output as a value of absolute temperature [K].

[0058] In S710, the diagnostic device 1 diagnoses the state of the lubricant based on the oil film temperature derived in S709. The contents of the diagnosis here are not particularly limited, but for example, a threshold value may be set for the oil film temperature, and the normality or abnormality may be diagnosed by comparing the oil film temperature with the threshold value.

[0059] In S711, the diagnostic device 1 notifies the user of the diagnosis result obtained in S710. The notification method here is not particularly limited, but for example, the oil film temperature value and temperature transitions may be displayed on the screen. Alternatively, the configuration may be such that an abnormal temperature rise according to the operating conditions is notified. Then, this processing flow ends.

[0060] As described above, according to this embodiment, even when it is difficult to directly measure the oil film temperature of the lubricant in a device that uses a lubricant, such as a rolling bearing, it is possible to derive the oil film temperature. Furthermore, based on this, it becomes possible to easily diagnose the state of the device.

[0061] <Other embodiments> In the above embodiment, an oil film formed by a lubricant in a rolling bearing has been described as an example, but the present invention is not limited to this. For example, the method according to the present invention can be applied to any substance used in a device for which direct temperature detection is difficult and which causes dielectric relaxation, and is not limited to lubricants. Furthermore, the device to which the method is applied is not limited to rolling bearings, and the method according to the present invention can be applied to other rolling devices that use substances that cause dielectric relaxation.

[0062] In the above example, a lithium-based grease was used as an example of the lubricant, but the present invention is not limited to this. As mentioned above, the method according to the present invention can also be applied to lubricants that cause dielectric relaxation.

[0063] Furthermore, the present invention can also be realized by supplying a program or application for realizing the functions of one or more of the above-described embodiments to a system or device via a network or storage medium, etc., and having one or more processors in the computer of that system or device read and execute the program.

[0064] Alternatively, it 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)).

[0065] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0066] As described above, the present specification discloses the following: (1) A temperature deriving method for deriving an oil film temperature of a lubricant in a device, comprising: a measuring step of measuring the dielectric constant of the lubricant by applying an AC voltage while changing the frequency to an electric circuit constituted by the device; a derivation step of applying the dielectric constant measured in the measurement step to a theoretical formula to derive a relaxation time of the lubricant; a calculation step of calculating the oil film temperature using the relaxation time; A temperature derivation method comprising: According to this configuration, even when it is difficult to directly measure the oil film temperature of the lubricant in a device that uses the lubricant, the oil film temperature can be derived.

[0067] (2) In the calculation step,

[0068]

number

[0069] The oil film temperature is calculated using Activation enthalpy ΔH ‡ , and activation entropy ΔS ‡ The temperature deriving method according to (1), characterized in that the value of the lubricant in a bulk state is used. According to this configuration, it is possible to easily derive the oil film temperature of the lubricant using information on the lubricant in a bulk state.

[0070] (3) The theoretical formula is

[0071]

number

[0072]

number

[0073]

number

[0074] 3. The temperature derivation method according to (1) or (2), characterized in that: According to this configuration, the electrical characteristics of the dielectric relaxation phenomenon caused by the lubricant in the device can be accurately determined, and the oil film temperature of the lubricant can be derived based on a value based on this electrical characteristic.

[0075] (4) The temperature deriving method according to any one of (1) to (3), further comprising a diagnosing step of diagnosing the state of the device using the oil film temperature calculated in the calculating step. This configuration also makes it possible to easily diagnose the state of the device based on the calculated oil film temperature.

[0076] (5) The temperature deriving method according to any one of (1) to (4), wherein the device is a rolling device. According to this configuration, even when it is difficult to actually measure the oil film temperature of the lubricant directly in the rolling device, the oil film temperature can be derived.

[0077] (6) The temperature deriving method according to any one of (1) to (4), wherein the device is a rolling bearing. According to this configuration, even when it is difficult to actually measure the oil film temperature of the lubricant directly in the rolling bearing, the oil film temperature can be derived.

[0078] (7) A temperature deriving device for detecting the oil film temperature of a lubricant in a device, a measuring means for measuring the dielectric constant of the lubricant by applying an AC voltage to an electric circuit constituted by the device while changing the frequency; a derivation means for applying the dielectric constant measured by the measurement means to a theoretical formula to derive a relaxation time of the lubricant; a calculation means for calculating the oil film temperature using the relaxation time; A temperature derivation device comprising: According to this configuration, even when it is difficult to directly measure the oil film temperature of the lubricant in a device that uses the lubricant, the oil film temperature can be derived.

[0079] (8) To the computer, a measuring step of measuring the dielectric constant of the lubricant in the device by applying an AC voltage while changing the frequency to an electric circuit constituted by the device; a derivation step of applying the dielectric constant measured in the measurement step to a theoretical formula to derive a relaxation time of the lubricant; a calculation step of calculating an oil film temperature of the lubricant using the relaxation time; A program to execute. According to this configuration, even when it is difficult to directly measure the oil film temperature of the lubricant in a device that uses the lubricant, the oil film temperature can be derived.

[0080] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0081] This application is based on a Japanese patent application filed on September 29, 2020 (Patent Application No. 2020-163962) and a Japanese patent application filed on August 25, 2021 (Patent Application No. 2021-137563), the contents of which are incorporated by reference into this application. [Explanation of symbols]

[0082] 1...Diagnostic equipment 2...Bearing device 3...Outer ring (outer member) 4...Inner ring (inner member) 5...Rolling element 6...Seal 7...Rotation axis 8...LCR meter 9...Rotating connector 10...Motor

Claims

1. A temperature deriving method for deriving an oil film temperature of a lubricant in a device, comprising: a measuring step of applying an AC voltage to an electric circuit constituted by the device while changing the frequency, thereby measuring the dielectric constant and the dielectric loss factor of the lubricant in accordance with the change in the frequency; a derivation step in which the actual measured values ​​of the dielectric constant and the dielectric loss factor measured in response to the changed frequency in the measurement step are applied to a theoretical equation of the dielectric constant and the dielectric loss factor having the frequency as a variable and at least a relaxation time as a parameter, and the identified parameter is derived as the relaxation time of the lubricant; a calculation step of calculating the oil film temperature using the derived relaxation time; A temperature derivation method comprising:

2. In the calculation step, [Equation 1] T: absolute temperature τ: relaxation time h: Planck's constant R: gas constant k B : Boltzmann constant ΔH ‡: activation enthalpy ΔS ‡: activation entropy exp: exponential function W: Lambert W function The oil film temperature is calculated using Activation enthalpy ΔH ‡ , and activation entropy ΔS ‡ 2. The temperature deriving method according to claim 1, wherein the value of the lubricant in a bulk state is used.

3. The theoretical formula is: [Equation 2] [Equation 3] [Equation 4] ε r ': relative permittivity ε r ″: relative dielectric loss factor ε r0: relative permittivity at the low frequency limit ε r∞: Relative permittivity at the high frequency limit τ: relaxation time β: constant representing the distribution of relaxation times σ 0: DC conductivity ε 0: Dielectric constant of vacuum π: pi f: frequency ω: Angular frequency of AC voltage ln: logarithmic function 3. The temperature deriving method according to claim 1, wherein the temperature deriving method is expressed as follows:

4. 4. The temperature deriving method according to claim 1, further comprising a diagnosing step of diagnosing a state of the device using the oil film temperature calculated in the calculating step.

5. The temperature deriving method according to any one of claims 1 to 4, characterized in that the device is a rolling device.

6. 5. The temperature deriving method according to claim 1, wherein the device is a rolling bearing.

7. A temperature deriving device for detecting an oil film temperature of a lubricant in a device, a measuring means for applying an AC voltage to an electric circuit constituted by the device while changing the frequency, thereby measuring the dielectric constant and the dielectric loss factor of the lubricant in accordance with the change in the frequency; a derivation means for applying the actual measured values ​​of the dielectric constant and the dielectric loss factor measured in response to the changed frequency by the measurement means to a theoretical equation of the dielectric constant and the dielectric loss factor having the frequency as a variable and at least a relaxation time as a parameter, and deriving the specified parameter as the relaxation time of the lubricant; a calculation means for calculating the oil film temperature using the derived relaxation time; A temperature derivation device comprising:

8. On the computer, a measuring step of applying an AC voltage to an electric circuit constituted by the device while changing the frequency, thereby measuring the dielectric constant and the dielectric loss factor of the lubricant in the device in accordance with the change in the frequency; a derivation step in which the actual measured values ​​of the dielectric constant and the dielectric loss factor measured in response to the changed frequency in the measurement step are applied to a theoretical equation of the dielectric constant and the dielectric loss factor having the frequency as a variable and at least a relaxation time as a parameter, and the identified parameter is derived as the relaxation time of the lubricant; a calculation step of calculating an oil film temperature of the lubricant using the derived relaxation time; A program to execute.

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