Bearing device state detection method, detection device, and program

Abstract

In a detection method for detecting the state of a bearing device configured to include a sliding bearing, an AC voltage is applied to an electric circuit comprising the sliding bearing and a rotating shaft, the impedance and phase angle of the electric circuit when the AC voltage is applied are measured, and the state of the bearing device is detected on the basis of the impedance and the phase angle. And deriving an oil film thickness and a metal contact ratio between the sliding bearing and the rotating shaft, the oil film thickness and the metal contact ratio being derived using a calculation formula corresponding to a circuit formed by line contact generated between the sliding bearing and the rotating shaft.

Description

Technical Field

[0001] The present invention relates to a method, a device and a program for detecting the state of a bearing device. Background Art

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

[0003] In a bearing device using a lubricant, in order to diagnose its operating state, it is required to appropriately detect the state related to the lubricant. For example, Patent Document 1 discloses a method of applying a low DC voltage to a bearing and diagnosing the state of the oil film in the bearing based on the measured voltage. In addition, Patent Document 2 discloses a method of modeling the oil film as a capacitor, applying an AC voltage to the rotating circle of the bearing in a non-contact state, and estimating the state of the oil film in the bearing device based on the measured electrostatic capacitance.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Utility Model Publication No. 05-003685

[0007] Patent Document 2: Japanese Patent No. 4942496 Summary of the invention

[0008] Technical problem that the invention aims to solve

[0009] In recent years, there is a demand for further low torque of bearing devices. Corresponding to the low torque, the lubricant used in the bearing device is continuously reduced in viscosity and oil content. On the other hand, for example, in the bearing device used for large devices such as windmills, a larger load will be loaded. Under such conditions, the possibility of oil film rupture inside the bearing device and the contact ratio between components become higher. Therefore, in addition to the oil film thickness, it is also required to properly detect the contact state between the components inside the bearing device. In addition, there are various types of bearing devices, such as sliding bearings. Inside such a bearing device, as it moves, line contact may occur between the rotating shaft and its surrounding components. For example, in the method of cited document 2, only the oil film thickness is measured, and it is difficult to grasp the metal contact ratio. In addition, since the electrostatic capacitance outside the contact area is not considered, the measurement accuracy is not high. Furthermore, the measurement is performed without considering line contact.

[0010] In view of the above problems, an object of the present invention is to detect the oil film thickness inside the bearing device and the metal contact ratio between components with high accuracy, taking into account the line contact generated inside the bearing device.

[0011] Technical solutions to the problem

[0012] In order to solve the above-mentioned problem, the present invention has the following structure. That is, a detection method for detecting the state of a bearing device configured to include a sliding bearing, wherein the detection method is characterized in that:

[0013] applying an AC voltage to a circuit formed by the sliding bearing and the rotating shaft,

[0014] measuring the impedance and phase angle of the circuit when the AC voltage is applied,

[0015] Based on the impedance and the phase angle, the oil film thickness and the metal contact ratio between the sliding bearing and the rotating shaft are derived.

[0016] The oil film thickness and the metal contact ratio are derived using a calculation formula corresponding to an electric circuit formed by line contact generated between the sliding bearing and the rotating shaft, which is generated in the bearing device.

[0017] In addition, another aspect of the present invention has the following structure. That is, a detection device is characterized in that it detects the state of a bearing device configured to include a sliding bearing, and the detection device has:

[0018] an acquisition unit that acquires, when an AC voltage is applied to a circuit formed by the sliding bearing and the rotating shaft, an impedance and a phase angle of the circuit when the AC voltage is applied; and

[0019] a deriving unit for deriving an oil film thickness and a metal contact ratio between the sliding bearing and the rotating shaft based on the impedance and the phase angle,

[0020] The derivation unit derives the oil film thickness and the metal contact ratio using a calculation formula corresponding to a circuit constituted by line contact generated between the sliding bearing and the rotating shaft generated in the bearing device.

[0021] In addition, another embodiment of the present invention has the following structure. That is, a program characterized in that:

[0022] The program is for causing the computer to function as the following means:

[0023] an acquisition unit for acquiring, for a bearing device including a sliding bearing, an impedance and a phase angle of the circuit when the AC voltage is applied, obtained when an AC voltage is applied to the circuit constituted by the sliding bearing and a rotating shaft; and

[0024] a deriving unit for deriving an oil film thickness and a metal contact ratio between the sliding bearing and the rotating shaft based on the impedance and the phase angle,

[0025] The derivation unit derives the oil film thickness and the metal contact ratio using a calculation formula corresponding to a circuit constituted by line contact generated between the sliding bearing and the rotating shaft generated in the bearing device.

[0026] In order to solve the above-mentioned problem, the present invention has the following structure. That is, a detection method is used to detect the state of a bearing device which is composed of an outer member, an inner member and a plurality of rollers, wherein the detection method is characterized in that:

[0027] In a state where a predetermined radial load is applied to the bearing device, an AC voltage is applied to a circuit formed by the outer member, the inner member, and the plurality of rollers.

[0028] measuring the impedance and phase angle of the circuit when the AC voltage is applied,

[0029] Based on the impedance and the phase angle, an oil film thickness and a metal contact ratio between at least one of the inner member and the plurality of rollers or between the inner member and the plurality of rollers are derived.

[0030] In addition, another aspect of the present invention has the following structure. That is, a detection device that detects the state of a bearing device that is configured to include an outer member, an inner member, and a plurality of rollers, wherein the detection device is characterized in that:

[0031] an acquisition unit that acquires the impedance and phase angle of the circuit when the AC voltage is applied, obtained when an AC voltage is applied to the circuit composed of the outer member, the inner member, and the plurality of rollers in a state where a predetermined radial load is applied to the bearing device; and

[0032] A deriving unit derives an oil film thickness and a metal contact ratio of at least one between the inner member and the plurality of rollers or between the inner member and the plurality of rollers based on the impedance and the phase angle.

[0033] In addition, another aspect of the present invention has the following structure. That is, a program characterized in that:

[0034] The program is for causing the computer to function as the following unit:

[0035] an acquisition unit that acquires impedance and a phase angle of the circuit when the AC voltage is applied, obtained when an AC voltage is applied to a circuit composed of the outer member, the inner member, and the plurality of rollers in a state where a predetermined radial load is applied to a bearing device composed of the outer member, the inner member, and the plurality of rollers; and

[0036] A deriving unit derives an oil film thickness and a metal contact ratio of at least one between the inner member and the plurality of rollers or between the inner member and the plurality of rollers based on the impedance and the phase angle.

[0037] Effects of the Invention

[0038] According to the present invention, it is possible to assume that line contact occurs inside the bearing device, and to detect the oil film thickness inside the bearing device and the contact ratio between components with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram showing an example of the configuration of a device during diagnosis according to the first embodiment of the present invention.

[0040] Figure 2 This is a diagram showing a physical model of the bearing device according to the first embodiment of the present invention.

[0041] Figure 3 This is a circuit diagram for explaining an equivalent circuit of a bearing device according to the first embodiment of the present invention.

[0042] Figure 4 It is a diagram for explaining rolling elements (balls) of a bearing device.

[0043] Figure 5 It is a diagram for explaining the rotation axis.

[0044] Figure 6 This is a diagram for explaining a sliding bearing and a rotating shaft.

[0045] Figure 7 It is a diagram for explaining the verification results according to the first embodiment of the present invention.

[0046] Figure 8 This is a flowchart of the process during measurement according to the first embodiment of the present invention.

[0047] Fig. 9 It is a schematic diagram showing an example of the configuration of a device during diagnosis according to the second embodiment of the present invention.

[0048] Fig.10 This is a circuit diagram for explaining an equivalent circuit of a bearing device according to a second embodiment of the present invention.

[0049] Fig.11 It is a diagram for explaining a load ring and a non-load ring according to a second embodiment of the present invention.

[0050] Fig. 12A It is a diagram for explaining the electrostatic capacitance of a load ring according to the second embodiment of the present invention.

[0051] Fig. 12B It is a diagram for explaining the electrostatic capacitance of a load ring according to the second embodiment of the present invention.

[0052] Fig.13 This is a circuit diagram for explaining an equivalent circuit according to the second embodiment of the present invention.

[0053] Fig.14A A graph showing measurement results according to the second embodiment of the present invention.

[0054] Fig. 14B A graph showing measurement results according to the second embodiment of the present invention.

[0055] Fig. 14C A graph showing measurement results according to the second embodiment of the present invention.

[0056] Fig.15A A graph showing measurement results according to the second embodiment of the present invention.

[0057] Fig. 15B A graph showing measurement results according to the second embodiment of the present invention.

[0058] Fig. 15C A graph showing measurement results according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0059] 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 an embodiment for describing 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 for solving the problems of the present invention. In addition, in each of the accompanying drawings, the same constituent elements are indicated by marking the same reference numerals to indicate the corresponding relationship.

[0060] <First Embodiment>

[0061] The first embodiment of the present invention is described below. In addition, in the following description of the device structure, a sliding bearing is used as an example, but it is not limited to this. The present invention can also be applied to devices of other structures. For example, it can be applied to a rolling device having a component that produces a sliding behavior described later.

[0062] [Device structure]

[0063] Figure 1 It is a schematic configuration diagram showing an example of the overall configuration when the diagnosis device 1 according to the present embodiment performs a diagnosis. Figure 1 A bearing device 2 to which the diagnostic method according to the present embodiment is applied and a diagnostic device 1 for performing the diagnosis are provided. Figure 1 The structure shown is an example, and a different structure may be used depending on the structure of the bearing device 2, etc. Figure 1 In FIG. 1 , the bearing device 2 is shown to include a single sliding bearing 3 , but the present invention is not limited thereto and a plurality of sliding bearings may be provided.

[0064] The bearing device 2 is configured to include a sliding bearing 3. In the bearing device 2, the sliding bearing 3 is provided around the rotating shaft 7 and is configured to be rotatable while making line contact with the rotating shaft 7. Inside the sliding bearing 3, the friction between the rotating shaft 7 and the sliding bearing 3 is reduced by a predetermined lubrication method. The lubrication method is not particularly limited, and grease lubrication, oil lubrication, etc. are used, for example, to supply grease or oil to the inside of the sliding bearing 3. The type of lubricant is also not particularly limited.

[0065] The motor 10 is a driving motor, and supplies power to the rotating shaft 7 by rotating. The rotating shaft 7 is connected to the LCR meter 8 via the rotating connector 9. The rotating connector 9 can be formed by using a carbon brush, for example, but is not limited to this. In addition, the sliding bearing 3 of the bearing device 2 is also electrically connected to the LCR meter 8, and at this time, the LCR meter 8 also functions as an AC power supply for the bearing device 2.

[0066] The diagnostic device 1 operates as a detection device capable of executing the detection method involved in this embodiment. During diagnosis, the diagnostic device 1 uses the angular frequency ω and the AC voltage V of the AC power supply as inputs to indicate the LCR meter 8, and obtains the impedance |Z| (|Z| represents the absolute value of Z) and the phase angle θ of the bearing device 2 from the LCR meter 8 as corresponding outputs. Then, the diagnostic device 1 uses these values ​​to detect the oil film thickness and the metal contact ratio in the bearing device 2. The details of the detection method will be described later.

[0067] The diagnostic device 1 can be realized, for example, by an information processing device that is constituted as 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 through sound, or it can be a visual notification through 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). For example, when abnormality diagnosis is performed based on the detection result, the notification content is not limited to notification when abnormality is detected, and may include notification indicating that bearing device 2 is normal.

[0068] [Physical model]

[0069] use Figure 2 The contact state between the sliding bearing 3 of the bearing device 2 and the rotating shaft 7 will be described. Figure 2 This is a diagram showing the physical model when the roller and the race are in contact (here, line contact). The roller corresponds to the rotating shaft 7, and the race corresponds to the sliding bearing 3. The h-axis represents the direction of the oil film thickness, and the y-axis represents the direction orthogonal to the oil film thickness direction. In addition, Figure 2 The variables shown are as follows: In addition, about the variables of each formula used in the following description, the same reference numerals are attached|subjected to the same variable, and correspondence is made.

[0070] S: Hertzian contact area

[0071] a: Contact width in the short side direction (here, x-axis direction) of the roller sheet (rotation axis)

[0072] α: Oil film rupture rate (metal contact ratio) (0≤α<1)

[0073] r: radius of the roller

[0074] αS: Actual contact area (rupture area of ​​oil film)

[0075] h: Oil film thickness

[0076] h1: Oil film thickness in the Hertzian contact area

[0077] O: The center of rotation of the roller

[0078] In the Hertzian contact region, the ratio of the area in contact with the metal to the area not in contact is α:(1-α). In addition, in the ideal state where the roller and the race are not in contact, α=0, and in the case of x=0, h>0.

[0079] Figure 2 The oil film thickness h shown is expressed by the following formula (1). In addition, the value of S shown here is Figure 1 Corresponding to the range of the x-axis direction.

[0080] h=f(x)=h1+√(r 2 -a 2 )-√(r 2 -x 2 ) (-r≤x<-a or a <x≤r) (1)

[0081] In the Hertzian contact region, there may be a region called a horseshoe-shaped region where the oil film is thin. However, in the present embodiment, the average oil film thickness in the Hertzian contact region, that is, the average oil film thickness h a Therefore, when the oil film breaks down in the Hertzian contact area, h a It is obtained by the following formula (2).

[0082] h a =(1-α)h1 (2)

[0083] exist Figure 2 In the equation, O is x=0, Figure 2 The coordinates of O in the equation are O(0, h1+√(r 2 -a 2 ))express.

[0084] It should be noted that, when the sliding bearing 3 is actually in motion, the rotating shaft 7 may be elastically deformed, so strictly speaking, its cross section may not be a perfect circle, but in this embodiment, the above-mentioned formula (1) is used as a perfect circle. Therefore, the formula used when calculating the oil film thickness is not limited to formula (1), and other calculation formulas (for example, in the case of gears, an involute curve is used) may also be used.

[0085] [Equivalent circuit]

[0086] Figure 3 It is expressed as an electrical equivalent circuit (equivalent circuit) Figure 2The physical model shown in FIG. The equivalent circuit E1 includes a resistor R1, a capacitor C1, and a capacitor C2. The resistor R1 corresponds to the resistor in the rupture region (=αS). The capacitor C1 corresponds to the capacitor formed by the oil film in the Hertz contact region, and is set to the electrostatic capacitance C1. The capacitor C2 corresponds to the peripheral ( Figure 2 The capacitor formed by the oil film of -r≤x<-a and a<x≤r) is defined as the electrostatic capacitance C2. The Hertz contact area (=S) is formed Figure 3 The equivalent circuit E1 of the resistor R1 and the capacitor C1 is a parallel circuit. In addition, the capacitor C2 is connected in parallel with the circuit including the resistor R1 and the capacitor C1. At this time, around the Hertz contact area ( Figure 2 -r≤x<-a and a<y≤r) is filled with lubricant.

[0087] 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).

[0088] V=|V|exp(jωt) (3)

[0089] I=|I|exp(j(ωt-θ)) (4)

[0090] Z=V / I=|V / I|exp(jθ)=|Z|exp(jθ) (5)

[0091] j: imaginary number

[0092] ω: angular frequency of AC voltage

[0093] t: time

[0094] θ: Phase angle (phase shift between voltage and current)

[0095] As shown in equation (5), the complex impedance Z is represented by two independent variables: the absolute value of Z |Z| and the phase angle θ. This means that by measuring the complex impedance Z, two independent parameters (in this embodiment, h shown below) can be measured. a and α). Figure 3 The complex impedance Z of the entire equivalent circuit shown is expressed as the following equation (6).

[0096] Z -1 =R1 -1 +jω(C1+C2) (6)

[0097] R1: resistance value of resistor R1

[0098] C1: The electrostatic capacitance of capacitor C1

[0099] C2: The electrostatic capacitance of capacitor C2

[0100] |Z|: Impedance in dynamic contact state

[0101] Furthermore, the following equations (7) and (8) can be derived from equation (6).

[0102] R1=|Z| / cosθ (7)

[0103] ω(C1+C2)=-sinθ / |Z| (8)

[0104] Here, since R1 in the formula (7) is inversely proportional to the contact area, it can be expressed as the following formula (9).

[0105] R1=R 10 / α (9)

[0106] R 10 : Resistance value at rest (i.e., α = 1)

[0107] R 10 It can be expressed as the following formula (10).

[0108] R 10 =|Z0| / cosθ0 (10)

[0109] |Z0|: Impedance in static contact state

[0110] θ0: Phase angle in static contact state

[0111] Therefore, according to equations (7), (9), and (10), the rupture rate α can be expressed as the following equation (11). When θ0 is set as the phase angle in the static contact state as described above, θ can be regarded as the phase angle in the dynamic contact state.

[0112] [Number 1]

[0113]

[0114] On the other hand, C1 in equations (6) and (8) can be expressed as in equation (12). In addition, assuming line contact, when the length of the rotating shaft 7 (here, the contact width in the longitudinal direction) is L, the contact area of ​​the Hertzian contact region S is S=2aL.

[0115] [Number 2]

[0116]

[0117] ε: Dielectric constant of lubricant

[0118] In addition, C2 in Formula (6) and Formula (8) can be expressed as in the following Formula (13).

[0119] [Number 3]

[0120]

[0121] [Electrostatic capacitance according to contact state]

[0122] Here, C2 among point contacts will be described. Figure 4 This is a diagram for explaining the case where the rolling element is a ball (for example, a ball bearing). Here, for ease of explanation, the value of h1 is shown to be large, but in fact, Figure 2 As shown, it is small enough to produce contact (point contact in this case). In this case, point contact may occur between the rolling element and the track plate.

[0123] and Figure 2 Similarly, when the radius of the rolling element is r and the oil film thickness is h1, Figure 3 The electrostatic capacitance of the capacitor C2 in the equivalent circuit shown can be calculated by the following formula (14).

[0124] [Number 4]

[0125]

[0126] π: Pi

[0127] r: radius of the ball

[0128] ε: Dielectric constant of lubricant

[0129] ln: logarithmic function

[0130] Next, a description will be given of a case where a line contact is generated in the present embodiment. Figure 5 3 is a diagram for explaining the state of the rotating shaft 7 and the sliding bearing 3. Figure 4 Similarly, for ease of explanation, the value of h1 is shown to be larger, but in fact, Figure 2 As shown in FIG. 1 , the distance between the rotating shaft 7 and the sliding bearing 3 is small enough to produce contact (in this case, line contact). In this case, line contact may be produced between the rotating shaft 7 and the sliding bearing 3. Figure 6 As shown, when the radius of the rotating shaft 7 is r1 and the radius of the inner diameter of the sliding bearing 3 is r2, r can be calculated as the equivalent curvature radius using r1 and r2. In this case, the surface of the sliding bearing 3 that makes line contact with the rotating shaft 7 has a negative curvature.

[0131] In addition, the oil film thickness at the position where the rotating shaft 7 and the sliding bearing 3 make line contact is denoted as h1. In this case, Figure 3 The electrostatic capacitance of the capacitor C2 in the equivalent circuit shown can be calculated by the above expression (13).

[0132] In addition, if Figure 5 As shown, the rotating shaft 7 is sometimes formed by chamfering the end. In this case, the straight line portion that may cause line contact can be treated as L. In addition, when the length ΔL in the long side direction based on the chamfer is extremely small relative to L, the length L' (=L+2ΔL) including the chamfered portion can also be used to calculate the capacitor C2.

[0133] At this time, if you use Figure 2 as well as Figure 5 , the contact area based on line contact (ie, the contact area of ​​the Hertzian contact region S) can be represented by 2aL.

[0134] In addition, for the chamfered portion, point contact is not produced, so for this portion, the capacitor C2 can be added to the calculation formula (13) using a calculation formula for C2 based on point contact (for example, the above-mentioned formula (14)).

[0135] An example of verifying the calculation result of capacitor C2 using the theoretical formula defined by the above formula (13) is shown. Here, a comparison is shown with the results of simulation analysis using the finite element method, which is a well-known method of electromagnetic field analysis. In addition, the following formula (15) based on Jackson, which is a well-known calculation formula, is represented as a comparison object. In addition, based on Jackson's formula, it is assumed that h1 is extremely large compared to r.

[0136] [Number 5]

[0137]

[0138] Figure 7 701 is a graph showing the verification results, where the horizontal axis represents the oil film thickness h1 [m] and the vertical axis represents the electrostatic capacitance C2 [F]. Line 701 represents the result obtained by calculating the electrostatic capacitance C2 using equation (13) as the calculation formula of this embodiment. Line 702 represents the result of calculating the electrostatic capacitance C2 using equation (15) as the calculation formula based on Jackson. In addition, symbol 703 (0) represents the result obtained by simulation based on the finite element method.

[0139] like Figure 7 As shown by the line 701 and the symbol 703 in FIG. 1 , the value of the electrostatic capacitance C2 calculated by using the formula (13) can be 1.0 -2This range corresponds to the size of the sliding bearing 3 assumed in the present invention (h1 is extremely small compared to r), and can also obtain high accuracy compared to the line 702 based on Jackson's equation (15).

[0140] [Derivation of oil film thickness and oil film rupture rate]

[0141] In this embodiment, the lubrication state is detected using the lubricant oil film thickness h1 and the oil film rupture rate α as described above. The following equation (16) is derived from the above equations (8) and (11) to (13).

[0142] [Number 6]

[0143]

[0144] At this time, ψ is defined as the following equation (17).

[0145] [Number 7]

[0146]

[0147] L: Length of the rotation axis

[0148] Moreover, according to equations (2) and (16), the average oil film thickness h a It is derived as shown in the following formula (18).

[0149] [Number 8]

[0150]

[0151] That is, by using equations (11) and (18), the complex impedance and phase angle at rest and when the oil film is formed can be measured, thereby simultaneously monitoring h a and α.

[0152] In addition, the above-mentioned formula (18) is a theoretical formula when there is only one contact area.

[0153] [Processing Flow]

[0154] Figure 8 This process is executed by the diagnostic device 1, and can be realized by, for example, causing a control device (not shown) included in the diagnostic device 1 to read a program for realizing the process of this embodiment from a storage device (not shown) and execute the program.

[0155] In S801, the diagnosis device 1 controls the bearing device 2 to apply a load in a predetermined direction. Figure 1In the case of a structure of , a load is applied to the rotating shaft 7. In addition, the control of the applied load may be performed by a device different from the diagnostic device 1. At this time, the phase angle and the impedance in the static contact state are measured.

[0156] In S802, the diagnostic device 1 starts rotating the rotating shaft 7 by the motor 10. Thus, the rotating shaft 7 rotates while generating line contact between the rotating shaft 7 and the sliding bearing 3. The motor 10 may be controlled by a device other than the diagnostic device 1.

[0157] In S803 , diagnostic device 1 controls LCR meter 8 so as to apply an AC voltage of angular frequency ω to bearing device 2 using an AC power source (not shown) provided in LCR meter 8 . Thus, an AC voltage of angular frequency ω is applied to bearing device 2 .

[0158] In S804, the diagnostic device 1 obtains the impedance |Z| and the phase angle θ as outputs in response to the input of S803 from the LCR meter 8. 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 for the AC voltage V and the angular frequency ω of the AC voltage as inputs.

[0159] In S805, the diagnostic device 1 applies the impedance |Z| and phase angle θ obtained in S804 and the angular frequency ω of the AC voltage used in S803 to equations (11) and (18) to derive the oil film thickness h (h in this embodiment). a ) and rupture rate α.

[0160] In S806, the diagnostic device 1 uses the oil film thickness h and the rupture rate α derived in S805 to diagnose the lubrication state of the bearing device 2. 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.

[0161] As described above, according to the present embodiment, the oil film thickness inside the bearing device and the contact ratio between components can be detected with high accuracy, assuming that line contact occurs inside the rolling bearing.

[0162] <Second Embodiment>

[0163] The second embodiment of the present invention is described below. In addition, in the following description, as a rolling bearing, a cylindrical roller bearing in which line contact may be generated inside is used as an example for description, but it is not limited to this, and the present invention can also be applied to rolling bearings of other structures. For example, as long as it is a rolling bearing in which line contact is generated inside, and a device using such a rolling bearing, the method of the present invention can be applied. Moreover, not limited to bearings, the present invention can also be applied to a device having a structure such that line contact described later is generated between parts lubricated with a lubricant. In addition, the description of the structure repeated in the first embodiment is omitted, and the description is focused on the differences.

[0164] [Device structure]

[0165] Fig. 9 1 is a schematic diagram showing an example of the overall structure when the diagnosis device 1 according to the present embodiment performs diagnosis. Fig. 9 A bearing device 12 to which the diagnostic method according to the present embodiment is applied and a diagnostic device 1 for performing the diagnosis are provided. It should be noted that: Fig. 9 The structure shown is an example, and a different structure may be used depending on the structure of the bearing device 2, etc. Fig. 9 In the figure, the bearing device 2 is shown to include one rolling bearing, but the present invention is not limited thereto, and a plurality of rolling bearings may be included in one bearing device 2. Here, the structure other than the bearing device 12 is the same as that shown in the first embodiment.

[0166] In the bearing device 12, a rolling bearing, which is a radial cylindrical roller bearing, supports the rotating shaft 7 so that it can rotate freely. The rotating shaft 7 is supported by a housing (not shown) covering the outer side of the rotating shaft 7 via the rolling bearing, which is a rotating member. The rolling bearing includes an outer ring (outer member) 13 as a fixed ring embedded in the housing, an inner ring (inner member) 14 as a rotating ring embedded outside the rotating shaft 7, a plurality of rollers as a plurality of rolling elements 15 arranged between the inner ring 14 and the outer ring 13, and a retainer (not shown) that retains the rolling elements 15 so that they can roll freely. Here, a structure in which the outer ring 13 is fixed is used, but a structure in which the inner ring 14 is fixed and the outer ring 13 is rotated may also be used. In addition, a peripheral member, namely a seal 16, is provided to prevent the intrusion of dirt into the periphery of the rolling element 15 and the leakage of lubricating oil. Inside the rolling bearing, the friction between the inner ring 14 and the rolling element 15 and between the outer ring 13 and the rolling element 15 is reduced by a predetermined lubrication method. The lubrication method is not particularly limited, and for example, grease lubrication, oil lubrication, etc. are used to supply grease or oil to the inside of the rolling bearing. The type of lubricant is also not particularly limited.

[0167] [Physical model]

[0168] Using the first embodiment Figure 2 , the contact state between the rolling element 15 and the outer ring 13 (or the inner ring 14) in the bearing device 12 is described. In this embodiment, Figure 2 It can be replaced by a physical model when the roller and the ring are in contact. The roller corresponds to the roller as the rolling element 15, and the ring corresponds to the outer ring 13 (or the inner ring 14). The h-axis represents the direction of the oil film thickness, and the y-axis represents the direction orthogonal to the oil film thickness direction. In addition, Figure 2 The variables shown are as follows: In addition, about the variables of each formula used in the following description, the same variable is denoted by the same code|symbol and corresponds.

[0169] S: Hertz contact area

[0170] a: Contact width of the roller in the short side direction (here, the x-axis direction)

[0171] α: Oil film rupture rate (metal contact ratio) (0≤α<1)

[0172] r: radius of the roller

[0173] αS: Actual contact area (rupture area of ​​oil film)

[0174] h: Oil film thickness

[0175] h1: Oil film thickness in the Hertzian contact area

[0176] O: The center of rotation of the roller

[0177] In the Hertzian contact region, the ratio of the metal contact area to the non-contact area is α:(1-α). In addition, in the ideal state where the roller and the ring are not in contact, α=0, and when x=0, h>0.

[0178] Next, using the first embodiment Figure 5 The case where line contact occurs in this embodiment is described. In this embodiment, the case where the rolling element is a roller (for example, a cylindrical roller bearing) is described. Figure 4 Similarly, for ease of explanation, the value of h1 is shown to be large, but in fact, as in the first embodiment Figure 2 As shown, it is small enough to produce contact (in this case, line contact). In this case, line contact may occur between the rolling element and the track plate. Figure 2 Similarly, when the radius of the rolling element is r and the oil film thickness is h1, Figure 3 The electrostatic capacitance of the capacitor C2 in the equivalent circuit shown can be calculated by the equation shown in the above equation (13).

[0179] Fig.10 Based on the first embodiment Figure 3 The equivalent circuit E1 shown is shown Fig. 9 15. If one of the rolling elements 15 is focused on, an equivalent circuit E2 is formed between the outer ring 13 and the rolling element 15, and between the inner ring 14 and the rolling element 15. Here, the upper side is described as a circuit formed by the outer ring 13 and the rolling element 15, and the lower side is described as a circuit formed by the inner ring 14 and the rolling element 15, but the reverse is also possible. Around one rolling element 15, these circuits, i.e. Figure 3 The equivalent circuits E1 are connected in series to form an equivalent circuit E2.

[0180] [Capacitance based on radial load]

[0181] Fig.11 1 is a diagram for explaining a load ring and a non-load ring when a radial load is applied to a rolling bearing. Here, a radial load F is applied to the rolling bearing via a rotating shaft 7. r In this case, among the plurality of rolling elements 15, Figure 2 The range of the Hertzian contact region shown is called the load circle, and the range other than this is called the non-load circle. In addition, the range of the load circle can be changed depending on the magnitude of the radial load, the structure of the rolling bearing, etc.

[0182] First, the electrostatic capacitance of the capacitor C1 in the load loop will be described. Fig. 12A as well as Fig. 12B This is a diagram for explaining the concept of capacitor C1 formed by rolling elements 15 located in the load ring. Here, an example is used to explain that the load ring includes five rolling elements and each rolling element forms capacitors C1(1) to C1(5). In the load ring, the size of the Hertzian contact area varies depending on the position of the rolling element. In this case, Fig. 12A As shown, it is also assumed that the electrostatic capacitance decreases as the distance from the center in the load circle increases.

[0183] However, if Figure 2 As shown, the oil film thickness h1 in the Hertz contact area is not easily affected by the radial load. In this embodiment, it is assumed that the oil film thickness in the load ring is constant. Based on this, Fig. 12B As shown, the Hertzian contact area S is averaged and the capacitances of the capacitors C1 formed by the plurality of rolling elements 15 in the load race are considered equal. Therefore, the capacitance of the capacitors C1 formed by the plurality of rolling elements 15 in the load race can be derived by the following equation (19).

[0184] [Number 9]

[0185]

[0186] m: A natural number representing the rolling element located in the load ring (1≤m≤n1)

[0187] n1: Number of rolling elements located in the load ring

[0188] C1(m): Electrostatic capacitance in the Hertzian contact area of ​​rolling element m

[0189] ￣

[0190] C1: Average value of C1(m)

[0191] Next, the electrostatic capacitance of the capacitor C3 in the non-loaded ring will be described. In the non-loaded ring, a gap between the rolling element 15 and the outer ring 13 and a gap between the rolling element 15 and the inner ring 14 are generated. Fig.11 As shown in the figure, the gap between the central rolling element 15a and the outer ring 13 and the gap between the rolling element 15a and the inner ring 14 in the rolling element 15 located in the non-load ring is set as the radial gap h gap In the case of , the gaps between each of the plurality of rolling elements 15 located in the non-loaded ring and the outer ring 13 can be derived from the following equation (20). In addition, the gap between the rolling element 15a and the outer ring 13 and the gap between the rolling element 15a and the inner ring 14 are the same (h gap / 2) is used to explain the case. In addition, the radial clearance h gap According to the radial load F r And the specifications of rolling bearings, etc. are derived.

[0192] [Number 10]

[0193]

[0194] m: A natural number representing the rolling element located in the non-loaded ring (1≤m≤(n-n1))

[0195] n: total number of rolling elements

[0196] n1: Number of rolling elements located in the load ring

[0197] Furthermore, based on equation (20), the electrostatic capacitance C3 of the entire non-load coil can be derived from the following equation (21).

[0198] [Number 11]

[0199]

[0200] m: A natural number representing the rolling element located in the non-loaded ring (1≤m≤(n-n1))

[0201] n: total number of rolling elements

[0202] n1: Number of rolling elements located in the load ring

[0203] ε: Dielectric constant of lubricant

[0204] C3(m): Electrostatic capacitance in the Hertzian contact area of ​​rolling element m

[0205] π: Pi

[0206] L: Length of rolling element (roller)

[0207] R tx : Effective radius of rolling element (roller)

[0208] h gap : Radial clearance

[0209] Fig.13 : is a diagram showing an equivalent circuit of the electrical equivalence of the entire bearing device 12, taking into account the capacitors formed in the load ring and the non-load ring. n equivalent circuits E2 are connected in parallel corresponding to the n rolling elements 15 located in the load ring. In this case, if Fig. 12A and Fig. 12B As described above, the electrostatic capacitance in the Hertzian contact region uses C1￣.

[0210] In addition, (n-n1) equivalent circuits E3 are connected in parallel to the (n-n1) rolling elements 15 located in the non-load ring. In addition, similarly to the load ring, capacitors are formed between the outer ring 13 and the rolling element 15 and between the inner ring 14 and the rolling element 15, respectively, so the equivalent circuit E3 has a structure in which two capacitors C3 are connected in series. Here, the upper side is set as a circuit formed by the outer ring 13 and the rolling element 15, and the lower side is set as a circuit formed by the inner ring 14 and the rolling element 15, but it can also be reversed. And, for the circuit formed by Fig.13 The equivalent circuit E4 formed by the entire bearing device 12 shown is supplied with AC power by the LCR meter 8 during diagnosis.

[0211] [Derivation of oil film thickness and oil film rupture rate]

[0212] In this embodiment, the lubrication state is detected using the lubricant film thickness h and the oil film rupture rate α under radial load. In this embodiment, in order to derive the lubricant film thickness h and the oil film rupture rate α under radial load, the above-mentioned formula (21) and the following formulas (22) to (25) are used.

[0213] [Number 12]

[0214]

[0215] [Number 13]

[0216]

[0217] [Number 14]

[0218]

[0219] [Number 15]

[0220]

[0221] n: the number of all rolling elements (rollers) in the bearing

[0222] n1: The number of rolling elements (rollers) located in the load ring

[0223] ￣

[0224] b: Average contact width of rolling element (roller)

[0225] L: Length of rolling element (roller)

[0226] R tx : Effective radius of rolling element (roller)

[0227] ￣

[0228] S t1 : Average contact area

[0229] S i1 (m): The contact area between the rolling element (roller) m and the inner ring

[0230] S o1 (m): The contact area between the rolling element (roller) m and the outer ring

[0231] ω: angular frequency of AC voltage

[0232] ε: Dielectric constant of lubricant

[0233] k: number of bearings

[0234] Ψ: dimensionless constant

[0235] h gap : Radial clearance

[0236] m: A natural number representing the rolling element located in the non-loaded ring (1≤m≤(n-n1))

[0237] |Z0|: Impedance in static contact state

[0238] θ0: Phase in static contact state

[0239] |Z|: Impedance in dynamic contact state

[0240] θ: Phase in dynamic contact state

[0241] In use Figure 2 In the description, 2a represents the contact width of the roller sheet, but since there are multiple rolling elements 15, their average value, that is, 2b, is used in the above formula (25).

[0243] The processing flow is the same as that of the first embodiment. However, in this embodiment, Figure 8 In S801, the diagnostic device 1 controls the bearing device 12 in a manner such that a radial load Fr is applied to the bearing device 12 in a predetermined load direction. Here, a radial load Fr is applied to the inner ring 14. r In addition, a radial load F is applied r The control may be performed by a device different from the diagnostic device 1. In this case, the phase and impedance in the static contact state are measured.

[0244] [Test 1]

[0245] The results of the test based on the above-mentioned diagnostic method are explained. Fig. 9 Based on the structure shown, the test conditions are as follows. In this test 1, a bearing in a wind turbine generator is used.

[0246] (Test conditions)

[0247] Test bearing: Cylindrical roller bearing (NU330EM)

[0248] Number of rolling elements (n):

[0249] Support bearing: ball bearing (NU2315EM (identification number: 6315); insulated with a resin sleeve so as not to affect the test results of the test bearing)

[0250] Rotation speed: 200~1800[min -1 ]

[0251] Axial load: 0[N]

[0252] Radial load (F r ): P / C = 0.1

[0253] Lubricant: Windmill GB gear oil VB320

[0254] Relative dielectric constant: 2.3

[0255] AC voltage: 1.1[V]

[0256] Frequency of AC power supply: 10[kHz]

[0257] External resistance: 51[Ω]

[0258] Figures 14A to 14C Graph showing the relationship between the rotation speed N, the oil film thickness h, the rupture rate α and the temperature T obtained from the test results under the above test conditions. Fig.14A In the figure, the horizontal axis represents the speed N [min -1 ], the vertical axis represents the oil film thickness h[m]. Fig. 14B In the figure, the horizontal axis represents the speed N [min -1 ], the vertical axis represents the rupture rate α. The vertical axis represents the oil film thickness h[m]. Fig. 14C In the figure, the horizontal axis represents the speed N [min -1 ], the vertical axis represents the temperature T. In each figure, the horizontal axis represents the rotation speed N [min -1 ] corresponds to the above test conditions. -1 ] are plotted.

[0259] exist Fig.14A In FIG. 1 , a dotted line 1101 indicates the oil film thickness derived as a theoretical value. A plot 1102 indicated by a solid line × indicates the result of deriving the oil film thickness h by using the above expression (22) taking into account the capacitors C1, C2, and C3. A plot 1103 indicated by a dotted line × indicates the result of deriving the oil film thickness h by using an expression taking into account only the capacitors C1 and C2. That is, the plot 1102 is the derived result taking into account the capacitor C3 composed of the non-loaded ring under radial load. Fig.14A As shown, the result shown in plot 1102 is closer to the theoretical value than the result shown in plot 1103, and the oil film thickness h can be derived with higher accuracy. Fig. 14B As shown in the curve 1111 of FIG. 1111, the rupture rate α can be derived together with the oil film thickness h at any rotation speed. In addition, even when the bearing temperature changes which are assumed to affect the viscosity of the lubricant, the present method can suppress the influence and calculate the oil film thickness h and the rupture rate α with high accuracy compared with the conventional method.

[0260] [Test 2]

[0261] The results of other tests based on the above diagnostic method are explained. Figure 1 The test conditions are as follows based on the structure shown. In addition, in this test 2, the influence of the flange provided around the raceway surface for rolling of the rolling element 15 in the outer ring 13 (or the inner ring 14, or both) is considered. Therefore, the test results based on the presence or absence of the flange are shown below.

[0262] (Test conditions)

[0263] Test bearings: Cylindrical roller bearings (NU330EM; with flange), cylindrical roller bearings (N330EM; without flange (with resin shim))

[0264] Number of rolling elements (n):

[0265] Support bearing: ball bearing (NU2315EM (identification number: 6315); insulated with a resin sleeve so as not to affect the test results of the test bearing)

[0266] Rotation speed: 200~1800[min -1 ]

[0267] Axial load: 0[N]

[0268] Radial load (F r ): P / C = 0.1

[0269] Lubricant: Windmill GB gear oil VB320

[0270] Relative dielectric constant: 2.3

[0271] AC voltage: 1.1[V]

[0272] Frequency of AC power supply: 10[kHz]

[0273] External resistance: 51[Ω]

[0274] Figures 15A to 15C Graph showing the relationship between the rotation speed N, the oil film thickness h, the rupture rate α and the temperature T obtained from the test results under the above test conditions. Fig.15A In the figure, the horizontal axis represents the speed N [min -1 ], the vertical axis represents the oil film thickness h[m]. Fig. 15B In the figure, the horizontal axis represents the speed N [min -1 ], the vertical axis represents the rupture rate α. The vertical axis represents the oil film thickness h[m]. Fig. 15C In the figure, the horizontal axis represents the speed N [min -1 ], the vertical axis represents the temperature T. In each figure, the horizontal axis represents the rotation speed N [min -1 ] corresponds to the above test conditions. -1 ] are plotted.

[0275] exist Fig.15AIn the figure, the dotted line 1201 represents the oil film thickness derived as a theoretical value. The plot 1202 indicated by × represents the result of deriving the oil film thickness h for a flangeless bearing using the above formula (22) taking into account the capacitors C1, C2, and C3. The plot 1203 indicated by 0 represents the result of deriving the oil film thickness h for a flanged bearing using the above formula (22) taking into account the capacitors C1, C2, and C3. Both are derived results taking into account the capacitor C3 composed of the non-load ring under radial load. Fig.15A As shown in , regardless of whether the bearing has a flange or not, the value is close to the theoretical value, and the oil film thickness h can be derived with higher accuracy. Fig. 15B As shown in the plots 1211 and 1212, the rupture rate α can be derived together with the oil film thickness h at any rotation speed. In addition, even when a temperature change of the bearing occurs, which is assumed to affect the viscosity of the lubricant, the present method can calculate the oil film thickness h and the rupture rate α with high accuracy regardless of the presence or absence of a flange.

[0276] As described above, according to the present embodiment, the oil film thickness inside the roller bearing device and the contact ratio of the sliding portion can be detected simultaneously with high accuracy under radial load.

[0277] <Other Implementation Methods>

[0278] In the second embodiment described above, radial loads are particularly focused on, and a radial bearing that generates the radial load is used for explanation. However, the above formulas can also be applied to thrust bearings that generate axial loads by adjusting the parameters of each variable. For example, Ψ in formula (22) and formula (24) can be applied to bearings that generate line contact of other structures by adjusting the parameters based on the specifications of the target bearing.

[0279] In addition, in the present invention, a program or application for implementing the functions of one or more of the above-mentioned embodiments may be supplied to a system or device using a network or storage medium, and may also be implemented by reading and executing the program by one or more processors in a computer of the system or device.

[0280] In addition, it can also be realized by a circuit that realizes more than one function (for example, ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array)).

[0281] 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.

[0282] As described above, the following matters are disclosed in this specification.

[0283] (1) A detection method for detecting a state of a bearing device configured to include a sliding bearing, wherein:

[0284] applying an AC voltage to a circuit formed by the sliding bearing and the rotating shaft,

[0285] measuring the impedance and phase angle of the circuit when the AC voltage is applied,

[0286] Based on the impedance and the phase angle, the oil film thickness and the metal contact ratio between the sliding bearing and the rotating shaft are derived.

[0287] The oil film thickness and the metal contact ratio are derived using a calculation formula corresponding to an electric circuit formed by line contact generated between the sliding bearing and the rotating shaft, which is generated in the bearing device.

[0288] According to the above configuration, it is possible to assume that line contact occurs inside the bearing device, and to detect the oil film thickness inside the bearing device and the contact ratio between components with high accuracy.

[0289] (2) The detection method according to (1), characterized in that:

[0290] The circuit formed by the wire contact includes: a resistor, which is generated by the wire contact; a first capacitor, which is composed of a lubricant located within a specified range from the wire contact; and a second capacitor, which is composed of a lubricant located outside the specified range.

[0291] According to the above configuration, the oil film thickness inside the bearing device and the contact ratio between components can be detected with high accuracy based on an equivalent circuit corresponding to the configuration of the bearing device.

[0292] (3) The detection method as described in (2), characterized in that

[0293] The electrostatic capacitance C1 of the first capacitor is represented by the following formula:

[0294] [Number 16]

[0295]

[0296] The electrostatic capacitance C2 of the second capacitor is represented by the following formula:

[0297] [Number 17]

[0298]

[0299] According to the above configuration, it is possible to derive the electrostatic capacitance of the capacitor in the equivalent circuit corresponding to the configuration of the bearing device with high accuracy.

[0300] (4) The detection method according to (2) or (3), characterized in that:

[0301] The calculation formula for deriving the oil film thickness h1 and the metal contact ratio α is:

[0302] [Number 18]

[0303]

[0304] [Number 19]

[0305]

[0306] [Number 20]

[0307]

[0308] According to the above configuration, it is possible to assume that line contact occurs inside the bearing device, and to detect the oil film thickness inside the bearing device and the contact ratio between components with high accuracy.

[0309] (5) The detection method according to any one of (1) to (4), characterized in that the bearing device is further diagnosed using the oil film thickness and the metal contact ratio.

[0310] According to the above configuration, the oil film thickness and the contact ratio between components in the bearing device are detected by assuming that line contact occurs in the bearing device, and based on the results, the state diagnosis of the bearing device can be performed with high accuracy.

[0311] (6) A detection device, characterized in that it detects the state of a bearing device configured to include a sliding bearing, the detection device comprising:

[0312] an acquisition unit that acquires, when an AC voltage is applied to a circuit formed by the sliding bearing and the rotating shaft, an impedance and a phase angle of the circuit when the AC voltage is applied; and

[0313] a deriving unit for deriving an oil film thickness and a metal contact ratio between the sliding bearing and the rotating shaft based on the impedance and the phase angle,

[0314] The derivation unit derives the oil film thickness and the metal contact ratio using a calculation formula corresponding to a circuit constituted by line contact generated between the sliding bearing and the rotating shaft generated in the bearing device.

[0315] According to the above configuration, it is possible to assume that line contact occurs inside the bearing device, and to detect the oil film thickness inside the bearing device and the contact ratio between components with high accuracy.

[0316] (7) A program for causing a computer to function as the following means:

[0317] an acquisition unit for acquiring, for a bearing device including a sliding bearing, an impedance and a phase angle of the circuit when the AC voltage is applied, obtained when an AC voltage is applied to the circuit constituted by the sliding bearing and a rotating shaft; and

[0318] a deriving unit for deriving an oil film thickness and a metal contact ratio between the sliding bearing and the rotating shaft based on the impedance and the phase angle,

[0319] The derivation unit derives the oil film thickness and the metal contact ratio using a calculation formula corresponding to a circuit constituted by line contact generated between the sliding bearing and the rotating shaft generated in the bearing device.

[0320] According to the above configuration, it is possible to assume that line contact occurs inside the bearing device, and to detect the oil film thickness inside the bearing device and the contact ratio between components with high accuracy.

[0321] As described above, the following matters are also disclosed in this specification.

[0322] (8) A detection method for detecting a state of a bearing device including an outer member, an inner member, and a plurality of rollers, wherein:

[0323] In a state where a predetermined radial load is applied to the bearing device, an AC voltage is applied to a circuit formed by the outer member, the inner member, and the plurality of rollers.

[0324] measuring the impedance and phase angle of the circuit when the AC voltage is applied,

[0325] Based on the impedance and the phase angle, an oil film thickness and a metal contact ratio of at least one between the inner member and the plurality of rollers or between the inner member and the plurality of rollers are derived.

[0326] According to this structure, the oil film thickness inside the roller bearing device under radial load and the metal contact ratio of the sliding part can be detected simultaneously with high accuracy. In particular, the line contact generated inside the roller bearing device can be taken into consideration and detected with high accuracy.

[0327] (9) The detection method according to (8) is characterized in that the oil film thickness and the metal contact ratio are derived using a calculation formula corresponding to the circuits respectively formed by the load ring and the non-load ring in the bearing device determined by the specified radial load.

[0328] According to this configuration, the oil film thickness and the sliding portion contact ratio inside the roller bearing device can be detected with high accuracy while taking into account the load ring and the non-load ring of the radial load.

[0329] (10) The detection method according to (9), characterized in that:

[0330] The calculation formula for deriving the oil film thickness h and the metal contact ratio α is:

[0331] [Number 21]

[0332]

[0333] [Number 22]

[0334]

[0335] [Number 23]

[0336]

[0337] [Number 24]

[0338]

[0339] [Number 25]

[0340]

[0341] According to this structure, the oil film thickness inside the roller bearing device under radial load and the metal contact ratio of the sliding part can be detected simultaneously with high accuracy. In particular, the oil film thickness inside the bearing device and the metal contact ratio of the sliding part can be detected taking into account the electrostatic capacitance corresponding to the load ring and the non-load ring of the rolling bearing that generate line contact.

[0342] (11) The detection method according to any one of (8) to (10), characterized in that the bearing device is also diagnosed using the oil film thickness and the metal contact ratio.

[0343] According to this configuration, the state of the rolling bearing related to the lubricant can be diagnosed based on the oil film thickness and the metal contact ratio determined according to the radial load.

[0344] (12) A detection device for detecting a state of a bearing device that includes an outer member, an inner member, and a plurality of rollers, the detection device comprising:

[0345] an acquisition unit that acquires the impedance and phase angle of the circuit when the AC voltage is applied, obtained when an AC voltage is applied to the circuit composed of the outer member, the inner member, and the plurality of rollers in a state where a predetermined radial load is applied to the bearing device; and

[0346] A deriving unit derives an oil film thickness and a metal contact ratio of at least one between the inner member and the plurality of rollers or between the inner member and the plurality of rollers based on the impedance and the phase angle.

[0347] According to this structure, the oil film thickness and the contact ratio of the sliding part in the roller bearing device under radial load can be detected simultaneously with high accuracy. In particular, the line contact generated in the roller bearing device can be taken into consideration and detected with high accuracy.

[0348] (13) A program for causing a computer to function as the following means:

[0349] an acquisition unit that acquires impedance and a phase angle of the circuit when the AC voltage is applied, obtained when an AC voltage is applied to a circuit composed of the outer member, the inner member, and the plurality of rollers in a state where a predetermined radial load is applied to a bearing device composed of the outer member, the inner member, and the plurality of rollers; and

[0350] A deriving unit derives an oil film thickness and a metal contact ratio of at least one between the inner member and the plurality of rollers or between the inner member and the plurality of rollers based on the impedance and the phase angle.

[0351] According to this structure, the oil film thickness and the contact ratio of the sliding part in the roller bearing device under radial load can be detected simultaneously with high accuracy. In particular, the line contact generated in the roller bearing device can be taken into consideration and detected with high accuracy.

[0352] 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.

[0353] In addition, this application is based on the Japanese patent application (Japanese Patent Application No. 2022-039416 and Japanese Patent Application No. 2022-039417) filed on March 14, 2022, the contents of which are incorporated herein by reference.

[0354] Description of Reference Numerals

[0355] 1 Diagnostic device

[0356] 2 Bearing assembly

[0357] 3 Sliding bearings

[0358] 7 Rotation axis

[0359] 8LCR Meter

[0360] 9 Rotary connector

[0361] 10 Motor

Claims

1. A detection method, characterized in that: detecting the state of a bearing device configured to include a sliding bearing, applying an AC voltage to a circuit formed by the sliding bearing and the rotating shaft, measuring the impedance and phase angle of the circuit when the AC voltage is applied, Based on the impedance and the phase angle, the oil film thickness and the metal contact ratio between the sliding bearing and the rotating shaft are derived. The oil film thickness and the metal contact ratio are derived using a calculation formula corresponding to an electric circuit formed by line contact generated between the sliding bearing and the rotating shaft, which is generated in the bearing device.

2. The detection method according to claim 1, characterized in that: The circuit formed by the wire contact includes: a resistor, which is generated by the wire contact; a first capacitor, which is composed of a lubricant located within a specified range from the wire contact; and a second capacitor, which is composed of a lubricant located outside the specified range.

3. The detection method according to claim 2, characterized in that: The electrostatic capacitance C1 of the first capacitor is represented by: [Number 1] ε: Dielectric constant of lubricant α: Oil film rupture rate (metal contact ratio) (0≤α<1) a: Contact width in the short side direction of the rotation axis L: Length of the rotation axis h1: oil film thickness in the Hertzian contact area, The electrostatic capacitance C2 of the second capacitor is expressed by: [Number 2] r: The radius of the roller.

4. The detection method according to claim 2 or 3, characterized in that: The calculation formula for deriving the oil film thickness h1 and the metal contact ratio α is: [Number 3] [Number 4] [Number 5] |Z|: Impedance in dynamic contact state |Z0|: Impedance in static contact state θ: Phase angle in dynamic contact state θ0: Phase angle in static contact state ε: Dielectric constant of lubricant α: Oil film rupture rate (metal contact ratio) (0≤α<1) a: Contact width in the short side direction of the rotation axis L: Length of the rotation axis h1: Oil film thickness in the Hertzian contact area r: radius of the roller ω: angular frequency of AC voltage.

5. The detection method according to any one of claims 1 to 4, characterized in that: Further, the oil film thickness and the metal contact ratio are used to diagnose the bearing device.

6. A detection device, characterized in that: detecting the state of a bearing device configured to include a sliding bearing, The detection device comprises: an acquisition unit that acquires, when an AC voltage is applied to a circuit formed by the sliding bearing and the rotating shaft, an impedance and a phase angle of the circuit when the AC voltage is applied; as well as a deriving unit for deriving an oil film thickness and a metal contact ratio between the sliding bearing and the rotating shaft based on the impedance and the phase angle, The derivation unit derives the oil film thickness and the metal contact ratio using a calculation formula corresponding to a circuit constituted by line contact generated between the sliding bearing and the rotating shaft generated in the bearing device.

7. A program, characterized in that The program is for causing the computer to function as the following means: an acquisition unit for acquiring, for a bearing device including a sliding bearing, an impedance and a phase angle of the circuit when the AC voltage is applied, obtained when an AC voltage is applied to the circuit formed by the sliding bearing and the rotating shaft; as well as a deriving unit for deriving an oil film thickness and a metal contact ratio between the sliding bearing and the rotating shaft based on the impedance and the phase angle, The derivation unit derives the oil film thickness and the metal contact ratio using a calculation formula corresponding to a circuit constituted by line contact generated between the sliding bearing and the rotating shaft generated in the bearing device.

8. A detection method, characterized in that: The state of the bearing device including an outer member, an inner member and a plurality of rollers is detected. In a state where a predetermined radial load is applied to the bearing device, an AC voltage is applied to a circuit formed by the outer member, the inner member, and the plurality of rollers. measuring the impedance and phase angle of the circuit when the AC voltage is applied, Based on the impedance and the phase angle, an oil film thickness and a metal contact ratio of at least one of between the inner member and the plurality of rollers or between the inner member and the plurality of rollers are derived.

9. The detection method according to claim 8, characterized in that: The oil film thickness and the metal contact ratio are derived using calculation formulas corresponding to circuits respectively constituted by the load ring and the non-load ring in the bearing device determined by the predetermined radial load.

10. The detection method according to claim 9, characterized in that: The calculation formula for deriving the oil film thickness h and the metal contact ratio α is: [Number 6] [Number 7] [Number 8] [Number 9] [Number 10] n: the total number of rolling elements in the bearing n1: The number of rolling elements located in the load ring ￣ b: Average contact width of rolling elements L: Length of rolling element R tx : Effective radius of rolling element ￣ S t1 : Average contact area S i1 (m): The contact area between the rolling element m and the inner ring S o1 (m): The contact area between rolling element m and the outer ring ω: angular frequency of AC voltage ε: Dielectric constant of lubricant k: number of bearings Ψ: dimensionless constant h gap : Radial clearance m: A natural number representing the rolling element located in the non-loaded circle (1≤m≤(n-n1)) |Z0|: Impedance in static contact state θ0: Phase in static contact state |Z|: Impedance in dynamic contact state θ: Phase in dynamic contact state.

11. The detection method according to any one of claims 8 to 10, characterized in that: Furthermore, the oil film thickness and the metal contact ratio are used to diagnose the bearing device.

12. A detection device, characterized in that: The state of a bearing device including an outer member, an inner member and a plurality of rollers is detected, and the device has: an acquisition unit that acquires impedance and a phase angle of the circuit when the AC voltage is applied, obtained when an AC voltage is applied to a circuit composed of the outer member, the inner member, and the plurality of rollers in a state where a predetermined radial load is applied to the bearing device; as well as A deriving unit derives an oil film thickness and a metal contact ratio of at least one of between the inner member and the plurality of rollers or between the inner member and the plurality of rollers based on the impedance and the phase angle.

13. A program, characterized in that The program is for causing the computer to function as the following means: an acquisition unit for acquiring impedance and phase angle of the circuit when the AC voltage is applied, obtained when an AC voltage is applied to a circuit composed of the outer member, the inner member, and the plurality of rollers in a state where a predetermined radial load is applied to a bearing device composed of the outer member, the inner member, and the plurality of rollers; as well as A deriving unit derives an oil film thickness and a metal contact ratio of at least one of between the inner member and the plurality of rollers or between the inner member and the plurality of rollers based on the impedance and the phase angle.

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