Bearing device state detection method, detection device, and program

Abstract

In a detection method for detecting the state of a bearing device including a tapered roller bearing, an AC voltage is applied to a circuit comprising an outer member, an inner member, and a plurality of rollers in a state where a predetermined load is applied to the bearing device, and the impedance and phase angle of the circuit when the AC voltage is applied are measured. Based on the impedance and the phase angle, an oil film thickness and a metal contact ratio in 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 using a calculation formula corresponding to the circuit.

Description

Technical Field

[0001] The present application relates to a method, a detection 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 have been 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 lower torque in bearing devices. In accordance with this lower torque, the lubricant used in the bearing device is being developed to have lower viscosity and lower oil content. On the other hand, for example, in bearing devices used in large devices such as windmills, a larger load is applied. Under such conditions, the possibility of oil film rupture inside the bearing device and the metal contact ratio of the sliding part increase. 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. There are various structures of the bearing used in the bearing device. Depending on the structure, it is sometimes necessary to consider the contact state between the components around the lubricant. For example, as an example of a bearing used in a bearing device, a tapered roller bearing can be cited. In a tapered roller bearing, in order to stabilize the position (guide) of the rolling element, a flange is sometimes provided on the inner ring side. Such a flange and the rolling element will come into contact when the tapered roller bearing is in operation, so it is necessary to consider these contacts for measurement.

[0010] In view of the above problems, an object of the present application is to simultaneously detect the oil film thickness inside a bearing device including a tapered roller bearing and the metal contact ratio of a sliding portion with high accuracy.

[0011] Technical solutions to the problem

[0012] In order to solve the above-mentioned problem, the present application has the following structure. That is, a detection method for detecting the state of a bearing device including a tapered roller bearing, wherein the tapered roller bearing is configured to include an outer member, an inner member, and a plurality of rollers, wherein the detection method is characterized in that:

[0013] In a state where a predetermined 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.

[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, an oil film thickness and a metal contact ratio in 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 using a calculation formula corresponding to the circuit.

[0016] In addition, another embodiment of the present application has the following structure. That is, a detection device is characterized in that it detects the state of a bearing device including a tapered roller bearing, wherein the tapered roller bearing is configured to include an outer member, an inner member, and a plurality of rollers,

[0017] The detection device comprises:

[0018] an acquisition unit, which acquires the 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 load is applied to the bearing device; and

[0019] A deriving unit derives 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 based on the impedance and the phase angle using a calculation formula corresponding to the circuit.

[0020] In addition, another aspect of the present application has the following structure. That is, a program for causing a computer to function as the following unit:

[0021] an acquisition unit that acquires impedance and a phase angle of a circuit when an alternating voltage is applied to a circuit constituted by the outer member, the inner member, and the plurality of rollers, when a prescribed load is applied to a bearing device including a tapered roller bearing and the tapered roller bearing is constituted to include an outer member, an inner member, and a plurality of rollers; and

[0022] A deriving unit derives 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 based on the impedance and the phase angle using a calculation formula corresponding to the circuit.

[0023] Effects of the Invention

[0024] According to the present application, the oil film thickness inside a bearing device including a tapered roller bearing and the metal contact ratio of a sliding portion can be detected simultaneously with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram showing an example of a device configuration during diagnosis according to the first embodiment of the present application.

[0026] Figure 2 It is a graph showing a physical model of the bearing device according to the first embodiment of the present application.

[0027] Figure 3 This is a circuit diagram for explaining an equivalent circuit of the bearing device according to the first embodiment of the present application.

[0028] Figure 4 It is a diagram for explaining rolling elements (balls) of a bearing device.

[0029] Figure 5 It is a diagram for explaining rolling elements (rollers) of a bearing device.

[0030] Figure 6 This is a circuit diagram for explaining the influence of the flange of a tapered roller bearing.

[0031] Figure 7 This is a graph for explaining the influence of the flange of a tapered roller bearing.

[0032] Figure 8 This is a schematic diagram for explaining the influence of the chamfer of a tapered roller bearing.

[0033] Fig.9A This is a graph for explaining the influence of the chamfer of a tapered roller bearing.

[0034] Fig. 9BThis is a graph for explaining the influence of the chamfer of a tapered roller bearing.

[0035] Fig. 9C This is a graph for explaining the influence of the chamfer of a tapered roller bearing.

[0036] Fig.10 This is a circuit diagram for explaining an equivalent circuit of the bearing device according to the first embodiment of the present application.

[0037] Fig.11 It is a diagram for explaining a load ring and a non-load ring according to the first embodiment of the present application.

[0038] Fig. 12A This is a diagram for explaining the electrostatic capacitance of the load coil according to the first embodiment of the present application.

[0039] Fig. 12B This is a diagram for explaining the electrostatic capacitance of the load coil according to the first embodiment of the present application.

[0040] Fig.13 This is a circuit diagram for explaining an equivalent circuit according to the first embodiment of the present application.

[0041] Fig.14 This is a flowchart of the process during measurement according to the first embodiment of the present application.

[0042] Fig.15A It is a graph showing the measurement results involved in the first embodiment of the present application.

[0043] Fig. 15B It is a graph showing the measurement results involved in the first embodiment of the present application. DETAILED DESCRIPTION

[0044] Hereinafter, the method for implementing the present application will be described with reference to the accompanying drawings and the like. In addition, the implementation method described below is used to illustrate an implementation method of the present application and is not intended to limit the interpretation of the present application. In addition, all structures described in each implementation method are not limited to structures necessary to solve the problems of the present application. 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.

[0045] <First Embodiment>

[0046] The first embodiment of the present application is described below. In addition, in the following description, as a rolling bearing, a tapered roller bearing in which line contact may be generated is used as an example for description, but it is not limited to this, and the present application can also be applied to rolling bearings of other structures. For example, as long as it is a rolling bearing having a flange similar to a tapered roller bearing in its interior, and a device using such a rolling bearing, the method of the present application can be applied. In addition, in the bearing device, as a structure that generates line contact, gears and the like can also be cited, but it can also be applied to these structures.

[0047] [Device structure]

[0048] 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 one rolling bearing, but the present invention is not limited thereto, and one bearing device 2 may include a plurality of rolling bearings.

[0049] In the bearing device 2, a rolling bearing as a radial tapered roller bearing supports the rotating shaft 7 so as to be rotatable. The rotating shaft 7 is supported by a housing (not shown) covering the outside of the rotating shaft 7 via the rolling bearing as a rotating member. The rolling bearing comprises: an outer ring (outer member) 3 as a fixed ring embedded in the housing, an inner ring (inner member) 4 as a rotating ring embedded on the outside of the rotating shaft 7, a plurality of rollers as a plurality of rolling elements 5 arranged between the inner ring 4 and the outer ring 3, and a retaining frame (not shown) for retaining the rolling elements 5 in a rolling manner. Here, a structure in which the outer ring 3 is fixed is used, but a structure in which the inner ring 4 is fixed and the outer ring 3 is rotated may also be used. In addition, a flange 6 for stabilizing the position of the rolling element 5 in the rolling surface is provided on the side of the inner ring 4. In other words, the flange 6 is guided by the rolling surface of the rolling element 5. In addition, although Figure 1 Although not shown in the figure, a seal as a peripheral component may be provided to prevent the intrusion of garbage into the periphery of the rolling element 5 and the leakage of lubricating oil. Inside the rolling bearing, the friction between the inner ring 4 (and the flange 6) and the rolling element 5, and between the outer ring 3 and the rolling element 5 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 the inside of the rolling bearing. There is no particular limitation on the type of lubricant.

[0050] 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 thereto. In addition, 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.

[0051] The diagnostic device 1 operates as a detection device capable of executing the detection method involved in the present 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 outputs relative thereto. 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.

[0052] 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 based on sound, or it can be a visual notification based on screen output. In addition, the output device can be a network interface with a communication function, and can also perform a notification action by sending data to an external device (not shown) via a network (not shown). 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 that the content is that bearing device 2 is normal.

[0053] [Physical Model]

[0054] use Figure 2 The contact state between the rolling element 5 and the outer ring 3 (or the inner ring 4 ) in the bearing device 2 will be described. Figure 2This is a graph showing the physical model when the roller and the ring are in contact. The roller corresponds to the roller as the rolling element 5, and the ring corresponds to the outer ring 3 (or the inner ring 4). The f(x) axis represents the direction of the oil film thickness. In addition, Figure 2 The variables shown are as follows: In the following description, the same variables are denoted by the same reference numerals and correspond to each other.

[0055] S: Hertzian contact area

[0056] a: Contact width of the roller in the short side direction (here, the x-axis direction)

[0057] α: Oil film rupture rate (metal contact ratio) (0≤α<1)

[0058] r: radius of the roller

[0059] αS: Actual contact area (break area of ​​oil film)

[0060] h: Oil film thickness

[0061] h1: Oil film thickness in the Hertzian contact region

[0062] O: The center of rotation of the roller

[0063] 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 h>0 when x=0.

[0064] Figure 2 The oil film thickness h shown is expressed by the following formula (1).

[0065] h=f(x)=h1+√(r 2 -a 2 )-√(r 2 -x 2 ) (-r≤x<-a or a <x≤r) (1)

[0066] 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 in the Hertzian contact region, h a It is obtained by the following formula (2).

[0067] h a =(1-α)h1 (2)

[0068] 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.

[0069] [Equivalent circuit]

[0070] Figure 3 It is expressed as an electrically equivalent circuit (equivalent circuit) Figure 2 The 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 fracture region (=αS). The capacitor C1 corresponds to the capacitor formed by the oil film in the Hertzian 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 with -r≤x<-a and a<x≤r) is defined as the electrostatic capacitance C2. The contact area (=S) of the Hertzian contact region 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 composed of the resistor R1 and the capacitor C1. At this time, around the Hertzian contact area ( Figure 2 -r≤x<-a and a<x≤r), filled with lubricant.

[0071] 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).

[0072] V=|V|exp(jωt) (3)

[0073] I=|I|exp(j(ωt-θ)) (4)

[0074] Z=V / I=|V / I|exp(jθ)=|Z|exp(jθ) (5)

[0075] j: imaginary number

[0076] ω: angular frequency of AC voltage

[0077] t: time

[0078] θ: Phase angle (phase shift between voltage and current)

[0079] 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).

[0080] Z -1 =R1 -1 +jω(C1+C2) (6)

[0081] R1: resistance value of resistor R1

[0082] C1: The electrostatic capacitance of capacitor C1

[0083] C2: The electrostatic capacitance of capacitor C2

[0084] |Z|: Impedance in dynamic contact state

[0085] Furthermore, the following equations (7) and (8) can be derived from equation (6).

[0086] R1=|Z| / cosθ (7)

[0087] ω(C1+C2)=-sinθ / |Z| (8)

[0088] Here, since R1 in the formula (7) is inversely proportional to the contact area, it can be expressed as the following formula (9).

[0089] R1=R 10 / α (9)

[0090] R 10 : Resistance value at rest (i.e., α = 1)

[0091] R 10 It can be expressed as the following formula (10).

[0092] R 10 =|Z0| / cosθ0 (10)

[0093] |Z0|: Impedance in static contact state

[0094] θ0: Phase angle in static contact state

[0095] Therefore, according to equations (7), (9), and (10), the fracture 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.

[0096] [Number 1]

[0097]

[0098] On the other hand, C1 in equations (6) and (8) can be expressed as in the following equation (12). It should be noted that, in the case of assuming line contact, when the length of the roller as the rolling element 5 (here, the contact width in the longitudinal direction) is set to L, Figure 2 The contact area S of the Hertzian contact region shown is S=2aL.

[0099] [Number 2]

[0100]

[0101] ε: Dielectric constant of lubricant

[0102] In addition, C2 in Formula (6) and Formula (8) can be expressed as in the following Formula (13).

[0103] [Number 3]

[0104]

[0105] [Electrostatic capacitance according to contact state]

[0106] 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 in FIG. 1 , the contact (in this case, point 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 following formula (14).

[0107] [Number 4]

[0108]

[0109] π: Pi

[0110] r: radius of the ball

[0111] ε: Dielectric constant of lubricant

[0112] ln: logarithmic function

[0113] Next, a case where a line contact is generated in the process in this embodiment will be described. Figure 5 This is a diagram for explaining the case where the rolling element is a roller (for example, a tapered roller bearing). Figure 4 Similarly, for ease of explanation, the value of h1 is shown to be larger, but in fact, Figure 2 As shown, it is small enough to cause 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).

[0114] In addition, if Figure 5 As shown in FIG. 1 , rollers used in rolling bearings are sometimes formed by chamfering the ends. 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 longitudinal 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. The details of the influence of the chamfered portion will be described later.

[0115] At this time, if you use Figure 2 as well as Figure 5 , the contact area of ​​the line contact (ie, the contact area S of the Hertzian contact region) can be represented by 2aL as described above.

[0116] In addition, for the chamfered portion, point contact may occur instead of line contact. Therefore, for this portion, the capacitor C2 may be added to the calculation formula (13) using a calculation formula for C2 based on point contact (for example, the above-mentioned formula (14)).

[0117] Here, it is explained that Figure 1 , Figure 5 In this embodiment, the flange 6 and the Figure 5 In this example, the case where the flange 6 is provided on the inner ring 4 side and there is no flange on the outer ring 3 side is described.

[0118] First, the influence of the contact between the flange 6 and the rolling element 5 on the electrostatic capacitance will be described. Figure 6 This is a diagram conceptually showing an equivalent circuit corresponding to the electrostatic capacitance caused by the contact area generated around the rolling element 5 (roller). Figure 6The circuit on the upper side represents the capacitor generated between the rolling element 5 and the outer ring 3, the circuit on the lower left side represents the capacitor generated between the rolling element 5 and the rolling surface of the inner ring 4, and the circuit on the lower right side represents the capacitor generated between the rolling element 5 and the flange 6 of the inner ring 4. The two capacitors on the lower side are represented as a parallel circuit. Here, for simplicity of explanation, it is assumed that the contact area S and the oil film thickness h of the Hertzian contact region of the capacitor on the lower left side and the capacitor on the lower right side are the same for explanation.

[0119] Figure 7 is for explaining the influence of the flange 6 based on the Figure 6 equivalent circuit shown. In Figure 7 , the vertical axis represents the ratio of the oil film thickness h 凸缘忽略 calculated by ignoring the electrostatic capacitance generated in the flange 6 to the oil film thickness h (i.e., the actually desired oil film thickness to be measured) between the rolling element 5 and the rolling surface of the inner ring 4. Additionally, in Figure 7 , the horizontal axis represents the ratio of the oil film thickness h 凸缘 generated in the flange 6 to the oil film thickness h between the rolling element 5 and the rolling surface of the inner ring 4. Additionally, the values on the curve graph represent the ratio of the Hertzian contact area S 凸缘 between the flange 6 and the rolling element 5 to the Hertzian contact area S of the rolling surface between the rolling element 5 and the inner ring 4.

[0120] For example, considering the structure of a tapered roller bearing, it is assumed that the contact area between the rolling element 5 and the flange 6 of the inner ring 4 is smaller than the contact area between the rolling element 5 and the rolling surface of the inner ring 4. That is, it is assumed to be S 凸缘 < S. Moreover, referring to Figure 7 , in the curve of S 凸缘 / S = 0.1, especially when the value of h 凸缘 / h exceeds 4, the value of h 凸缘忽略 / h is approximately 1. In other words, regardless of the presence or absence of the flange, approximately the same value can be obtained. That is, even if the flange is ignored in the subsequent measurement, approximately the same measurement accuracy can be obtained. Or it can be known that under any conditions, h 凸缘忽略 / h > 0.5. Generally, h 凸缘 / h ≈ 4, but even when h 凸缘 is very thin and S 凸缘 / S is very large, the h 凸缘忽略 obtained by ignoring the electrostatic charge generated by the flange compared to the oil film thickness h between the rolling element 5 and the rolling surface of the inner ring 4 that is actually desired to be measured will not be evaluated as being 50% thinner or more. Additionally, under any conditions, h 凸缘忽略 / h<1, so even if the amount of static electricity generated in the flange is ignored, it will not be evaluated to be thicker than the actual thickness. Therefore, as a device for monitoring the lubrication state, judgment is made in consideration of the safety factor.

[0121] Next, Figure 5 The influence of the chamfer in the rolling element 5 shown will be described. Figure 8 (a) indicates Figure 5 Similarly, an example of a rolling element with chamfered edges is Figure 8 (b) shows an example of a rolling element without chamfering. Figure 8 In (a), R c Indicates the radius of curvature of the chamfer (convex surface). Figure 8 The capacitance of the chamfered rolling element in (a) is set as C2, and Figure 8 The capacitance of the rolling element without chamfer (b) is C 2S In addition, let L' be the length of the rolling element in the longitudinal direction, and let L be the length L obtained by subtracting the chamfered portion from L'. In this case, L<L'.

[0122] Fig.9A is a graph used to illustrate the effect of chamfering. Fig.9A In the figure, the vertical axis represents C 2S The ratio of C2 2S / C2), the horizontal axis represents the oil film thickness h. 2S The closer the value of / C2 is to 1, the smaller the impact of the chamfer. Fig.9A It can be seen that if h<1.0×10 4 [nm](=10[μm]), then C 2S The value of / C2 gradually approaches 1, so even if the electrostatic capacitance generated in the chamfer is ignored, it will not have a significant impact on the oil film measurement accuracy.

[0123] Fig. 9B It is used to illustrate the curvature radius R c In case the value of C changes 2S The vertical axis represents C 2S The ratio of C2 2S / C2), the horizontal axis represents the oil film thickness h. Here, R c = 0.1, 1, 5, 10, 20 [m] these five results. Fig. 9B , even for any curvature radius R c , also with Fig.9A Similarly, as long as h < 1.0 × 10 4 [nm] (=10 [μm]), the chamfer can be ignored. In other words, the measurement described below can be performed regardless of the presence or absence of chamfer.

[0124] Fig. 9C This is a graph for explaining the relationship between L / L' and the oil film thickness h when the ratio of the length L' in the longitudinal direction of the rolling element to the length L is changed. 2S The ratio of C2 2S / C2), the horizontal axis represents the oil film thickness h. Here, four results are shown: L / L' = 0, 0.25, 0.5, and 0.75. Fig. 9C , if L / L'≤0.5, then Fig.9A Same, when h<1.0×10 4 [nm] (=10 [μm]), there is no problem even if the chamfer is ignored. However, it is known that the influence of the electrostatic capacitance generated by the chamfer on the oil film measurement accuracy cannot be ignored within the range of L / L'>0.5. However, the roller bearings generally in circulation satisfy L / L'≤0.5.

[0125] According to the above results, in this embodiment, the flange and chamfer in the structure of the tapered roller bearing are ignored for measurement. In this case, it is possible to measure with a certain degree of accuracy according to the structure of the tapered roller bearing. In addition, even if both the outer ring 3 and the inner ring 4 are provided with flanges, the method of this embodiment can be applied.

[0126] Fig.10 is based on Figure 3 The equivalent circuit E1 shown is shown Figure 1 The figure shows the electrical equivalent circuit around the rolling element 5. If we focus on one rolling element 5 among the multiple rolling elements 5, an equivalent circuit E2 is formed between the outer ring 3 and the rolling element 5, and between the inner ring 4 and the rolling element 5. Here, the upper side is described as the circuit formed by the outer ring 3 and the rolling element 5, and the lower side is described as the circuit formed by the inner ring 4 and the rolling element 5, but the reverse is also possible. Around one rolling element 5, these circuits, i.e. Figure 3 The equivalent circuits E1 are connected in series to form an equivalent circuit E2.

[0127] [Capacitance based on radial load]

[0128] 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, in the plurality of rolling elements 5, Figure 2 The range of the Hertzian contact area shown is called the load zone, and the range outside it is called the non-load zone. In addition, the range of the load zone can be changed depending on the size of the radial load, the structure of the rolling bearing, etc.

[0129] 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 5 located in the load ring. Here, an example is used to explain that the load ring includes 5 rolling elements, and capacitors C1(1) to C1(5) are formed by each rolling element. 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.

[0130] However, if Figure 2 As shown in FIG. 1 , the oil film thickness h1 in the Hertzian contact region is not easily affected by the radial load. In this embodiment, it is assumed that the oil film thickness in the load circle is constant. Based on this, Fig. 12B As shown, the Hertzian contact area S is averaged, and the capacitance of the capacitor C1 formed by the plurality of rolling elements 5 in the load race is considered uniform. Therefore, the capacitance of the capacitor C1 formed by the plurality of rolling elements 5 in the load race can be derived by the following equation (15).

[0131] [Number 5]

[0132]

[0133] m: A natural number representing the rolling element located in the load ring (1≤m≤n1)

[0134] n1: Number of rolling elements located in the load ring

[0135] C1(m): Electrostatic capacitance in the Hertzian contact area of ​​rolling element m

[0136] C1ˉ: Average value of C1(m)

[0137] Next, the capacitance of capacitor C3 in the non-load region is described. In the non-load ring, a gap is generated between the rolling element 5 and the outer ring 3, and a gap is generated between the rolling element 5 and the inner ring 4. Fig.11 As shown in the figure, the gap between the central rolling element 5a and the outer ring 3 and the gap between the rolling element 5a and the inner ring 4 in the rolling element 5 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 5 located in the non-loaded ring and the outer ring 3 can be derived according to the following formula (16). In addition, it is assumed that the gap between the rolling element 5a and the outer ring 3 and the gap between the rolling element 5a and the inner ring 4 are the same (h gap / 2) is used to illustrate. In addition, the radial clearance h gap According to the radial load F r And the specifications of rolling bearings, etc. are derived.

[0138] [Number 6]

[0139]

[0140] m: A natural number representing the rolling element located in the non-loaded ring (1≤m≤(n-n1))

[0141] n: total number of rolling elements

[0142] n1: Number of rolling elements located in the load ring

[0143] Furthermore, based on equation (16), the electrostatic capacitance C3 of the entire non-load coil can be derived from the following equation (17).

[0144] [Number 7]

[0145]

[0146] m: A natural number representing the rolling element located in the non-loaded ring (1≤m≤(n-n1))

[0147] n: total number of rolling elements

[0148] n1: Number of rolling elements located in the load ring

[0149] ε: Dielectric constant of lubricant

[0150] C3(m): Electrostatic capacitance in the Hertzian contact area of ​​rolling element m

[0151] π: Pi

[0152] L: Length of rolling element (roller)

[0153] R tx : Effective radius of rolling element (roller)

[0154] h gap : Radial clearance

[0155] Fig.13 This is a diagram showing an equivalent circuit of the electrical equivalence of the entire bearing device 2, 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 5 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 C1ˉ.

[0156] In addition, corresponding to the (n-n1) rolling elements 5 located in the non-load ring, (n-n1) equivalent circuits E3 are connected in parallel. It should be noted that, similarly to the load ring, capacitors are formed between the outer ring 3 and the rolling elements 5, and between the inner ring 4 and the rolling elements 5, 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 3 and the rolling elements 5, and the lower side is set as a circuit formed by the inner ring 4 and the rolling elements 5, but it can also be reversed. And, for the circuit formed by Fig.13 The equivalent circuit E4 formed by the entire bearing device 2 shown is supplied with AC power by the LCR meter 8 during diagnosis.

[0157] [Derivation of oil film thickness and oil film rupture rate]

[0158] 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 (17) and the following formulas (18) to (21) are used.

[0159] [Number 8]

[0160]

[0161] [Number 9]

[0162]

[0163] [Number 10]

[0164]

[0165] [Number 11]

[0166]

[0167] n: the number of all rolling elements (rollers) in the bearing

[0168] n1: The number of rolling elements (rollers) located in the load ring

[0169] bˉ: Average contact width of rolling element (roller)

[0170] L: Length of rolling element (roller)

[0171] R tx : Effective radius of rolling element (roller)

[0172] S t1 ˉ: Average contact area

[0173] S i1(m): The contact area between the rolling element (roller) m and the inner ring

[0174] S o1 (m): The contact area between the rolling element (roller) m and the outer ring

[0175] ω: angular frequency of AC voltage

[0176] ε: Dielectric constant of lubricant

[0177] k: number of bearings

[0178] Ψ: dimensionless constant

[0179] h gap : Radial clearance

[0180] m: A natural number representing the rolling element located in the non-loaded ring (1≤m≤(n-n1))

[0181] |Z0|: Impedance in static contact state

[0182] θ0: Phase in static contact state

[0183] |Z|: Impedance in dynamic contact state

[0184] θ: Phase in dynamic contact state

[0185] exist Figure 2 In the description, 2a represents the contact width of the roller sheet, but since there are multiple rolling elements 5, their average, i.e., 2bˉ, is used in the above formula (21).

[0186] [Processing Flow]

[0187] Fig.14 This process is executed by the diagnostic device 1 , and can be realized by, for example, a control device (not shown) included in the diagnostic device 1 reading a program for realizing the process of this embodiment from a storage device (not shown) and executing the program.

[0188] In S1401, the diagnostic device 1 controls the bearing device 2 so that a radial load Fr is applied to the bearing device 2 in a predetermined load direction. 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.

[0189] In S1402, the diagnostic device 1 starts rotating the rotating shaft 7 by the motor 10. As a result, the inner ring 4 connected to the rotating shaft 7 starts rotating. The motor 10 may be controlled by a device other than the diagnostic device 1.

[0190] In S1403 , diagnostic device 1 controls LCR meter 8 so that an AC voltage of angular frequency ω is applied 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 .

[0191] In S1404, the diagnostic device 1 obtains the impedance |Z| and the phase angle θ as outputs for the input in S1403 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.

[0192] In S1405 , the diagnostic device 1 applies the impedance |Z| and phase angle θ acquired in S1404 and the angular frequency ω of the AC voltage used in S1403 to equations (17) to (21) to derive the oil film thickness h and the rupture rate α.

[0193] In S1406, the diagnostic device 1 uses the oil film thickness h and the fracture rate α derived in S1405 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 fracture rate α, and judge the lubrication state by comparing with the threshold value. Then, this processing flow ends.

[0194] [test]

[0195] The results of the test based on the above-mentioned diagnostic method are explained. Figure 1 Based on the structure shown, the test conditions are as follows.

[0196] (Test conditions)

[0197] Test bearing: tapered roller bearing

[0198] Lubricant: turbine oil

[0199] Radial load: 53.5[kN]

[0200] Axial load: 0[N]

[0201] Temperature: Room temperature (at the beginning)

[0202] Speed: 50~1200[min -1 ]

[0203] AC voltage: 1.1[V]

[0204] Frequency of AC power supply: 100[kHz]

[0205] Fig.15AThis is a graph showing the relationship between the oil film thickness h, time and the fracture rate α (metal contact ratio) obtained from the test results under the above test conditions. Fig.15A In the figure, the horizontal axis represents the time [hr] from the start of the test, the left vertical axis represents the oil film thickness [μm], and the right vertical axis represents the fracture rate. Plotted point 1501 represents the change in fracture rate, corresponding to the scale on the right. Plotted point 1503 represents the change in oil film thickness, corresponding to the scale on the left. Curve 1502 is the theoretical value of oil film thickness.

[0206] Fig. 15B This is a graph showing the relationship between the rotation speed, time, and bearing temperature obtained from the test results under the above test conditions. Fig. 15B In the figure, the horizontal axis represents the time [hr] from the start of the test, the left vertical axis represents the rotation speed [rpm], and the right vertical axis represents the bearing outer ring temperature [°C]. Curve 1511 represents the change in temperature, corresponding to the scale on the right. Curve 1512 represents the change in rotation speed, corresponding to the scale on the left. In addition, Fig.15A and Fig. 15B The horizontal axis corresponds to .

[0207] Reference Fig.15A , Fig. 15B For example, when the time is about 0.5 [hr], the rupture rate increases, and the oil film thickness also decreases accordingly. At this time, due to the high rotation speed of the bearing, it is expected that the lubrication is exhausted and the oil film breaks. In addition, the calculated value of the oil film thickness obtained based on the method involved in this embodiment ignores the electrostatic capacitance generated in the flange, so it is safer than the theoretical value, that is, it becomes a value that can detect the situation of insufficient oil film thickness earlier. Therefore, in the diagnostic device 1 involved in this embodiment, the state change of the bearing device 2, especially the situation of insufficient oil film thickness, can be detected as early as possible.

[0208] As described above, according to the present embodiment, the oil film thickness inside the bearing device including the tapered roller bearing and the metal contact ratio of the sliding portion can be detected simultaneously with high accuracy.

[0209] <Other Implementation Methods>

[0210] In addition, in the present application, a program or application for implementing the functions of one or more of the above-mentioned embodiments is supplied to a system or device using a network or storage medium, and one or more processors in a computer of the system or device can also implement the processing by reading and executing the program.

[0211] 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)).

[0212] Thus, the present application is not limited to the above-mentioned embodiments, and combining the structures of the embodiments with each other, and making changes and applications by those skilled in the art based on the description in the specification and known technologies are also the intended contents of the present application and are included in the scope of protection required.

[0213] As described above, the following matters are disclosed in this specification.

[0214] (1) A detection method for detecting a state of a bearing device including a tapered roller bearing, wherein the tapered roller bearing is configured to include an outer member, an inner member, and a plurality of rollers, wherein:

[0215] In a state where a predetermined 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.

[0216] measuring the impedance and phase angle of the circuit when the AC voltage is applied,

[0217] Based on the impedance and the phase angle, an oil film thickness and a metal contact ratio in 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 using a calculation formula corresponding to the circuit.

[0218] According to this configuration, the oil film thickness inside the bearing device including the tapered roller bearing and the metal contact ratio of the sliding portion 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.

[0219] (2) The detection method according to (1) is characterized in that the calculation formula for deriving the oil film thickness h and the metal contact ratio α is:

[0220] [Number 12]

[0221]

[0222] [Number 13]

[0223]

[0224] [Number 14]

[0225]

[0226] [Number 15]

[0227]

[0228] [Number 16]

[0229]

[0230] According to this configuration, the oil film thickness inside the bearing device including the tapered roller bearing and the metal contact ratio of the sliding portion can be detected simultaneously with high accuracy.

[0231] (3) The detection method according to (1) or (2), wherein the calculation formula can be applied regardless of whether or not chamfers are provided on each of the plurality of rollers.

[0232] According to this configuration, regardless of whether or not the rolling elements in the tapered or cylindrical roller bearing are provided with chamfers, the oil film thickness and the metal contact ratio of the sliding portion can be detected simultaneously with high accuracy.

[0233] (4) The detection method according to any one of (1) to (3), wherein the calculation formula can be applied regardless of whether at least one of the outer member and the inner member has a flange for guiding the plurality of rollers.

[0234] According to this configuration, regardless of whether the flange is provided on the outer ring or the inner ring in the tapered or cylindrical roller bearing, the oil film thickness and the metal contact ratio of the sliding portion can be detected simultaneously with high accuracy.

[0235] (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.

[0236] According to this configuration, the state of the tapered or cylindrical roller bearing related to the lubricant can be diagnosed based on the oil film thickness and the metal contact ratio.

[0237] (6) A detection device, characterized in that it detects the state of a bearing device including a tapered roller bearing, wherein the tapered roller bearing is configured to include an outer member, an inner member, and a plurality of rollers,

[0238] The detection device comprises: an acquisition unit, which acquires the 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 load is applied to the bearing device; and

[0239] A deriving unit derives 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 based on the impedance and the phase angle using a calculation formula corresponding to the circuit.

[0240] According to this structure, the oil film thickness inside the bearing device including the tapered roller bearing 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.

[0241] (7) A program for causing a computer to function as the following means:

[0242] an acquisition unit that acquires impedance and a phase angle of a circuit when an alternating voltage is applied, obtained when an alternating voltage is applied to a circuit constituted by the outer member, the inner member, and the plurality of rollers, in a state where a predetermined load is applied to a bearing device including a tapered roller bearing and the tapered roller bearing is constituted to include an outer member, an inner member, and a plurality of rollers; and

[0243] A deriving unit derives 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 based on the impedance and the phase angle using a calculation formula corresponding to the circuit.

[0244] According to this structure, the oil film thickness inside the bearing device including the tapered roller bearing 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.

[0245] In the above, various embodiments are described with reference to the accompanying drawings, but the present application is certainly not limited to this example. As long as a person skilled in the art can think of various variations or modifications within the scope described in the claims, it is obvious that these variations or modifications also belong to the technical scope of the present application. In addition, the various constituent elements in the above embodiments may also be arbitrarily combined within the scope of the gist of the invention.

[0246] Various embodiments have been described above, but the present application is certainly not limited to this example. 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 application. 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.

[0247] In addition, this application is based on the Japanese patent application (Japanese Patent Application No. 2022-066449) filed on April 13, 2022, and the contents are incorporated herein by reference.

[0248] Description of Reference Numerals

[0249] 1 Diagnostic device

[0250] 2 Bearing assembly

[0251] 3 Outer ring (outer part)

[0252] 4Inner ring (inner part)

[0253] 5 rolling element (roller)

[0254] 6 Flange

[0255] 7 Rotation axis

[0256] 8 LCR Meter

[0257] 9 Rotary connector

[0258] 10 Motor

Claims

1. A detection method for detecting a state of a bearing device including a tapered roller bearing, wherein the tapered roller bearing is configured to include an outer member, an inner member, and a plurality of rollers, wherein the detection method is characterized in that: In a state where a predetermined 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 in 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 using a calculation formula corresponding to the circuit.

2. The detection method according to claim 1, characterized in that: The calculation formula for deriving the oil film thickness h and the metal contact ratio α is: [Number 1] [Number 2] [Number 3] [Number 4] [Number 5] n: the number of all rolling elements (rollers) in the bearing n1: The number of rolling elements (rollers) located in the load ring bˉ: Average contact width of rolling element (roller) L: Length of rolling element (roller) R tx : Effective radius of rolling element (roller) S t1 ˉ: Average contact area S i1 (m): The contact area between the rolling element (roller) m and the inner ring S o1 (m): The contact area between the rolling element (roller) 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.

3. The detection method according to claim 1, characterized in that: The calculation formula can be applied regardless of whether or not chamfers are provided on each of the plurality of rollers.

4. The detection method according to claim 1, characterized in that: The calculation formula is applicable regardless of whether or not at least one of the outer member and the inner member has a flange for guiding the plurality of rollers.

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

6. A detection device, characterized in that: detecting a state of a bearing device including a tapered roller bearing, wherein the tapered roller bearing is configured to include an outer member, an inner member, and a plurality of rollers, The detection device comprises: an acquisition unit, which acquires the 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 load is applied to the bearing device; as well as A deriving unit derives 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 based on the impedance and the phase angle using a calculation formula corresponding to the circuit.

7. A program, characterized in that The program is for causing the computer to function as the following means: an acquisition unit, wherein when a predetermined load is applied to a bearing device including a tapered roller bearing and the tapered roller bearing is configured to include an outer member, an inner member, and a plurality of rollers, the acquisition unit acquires impedance and a phase angle of the circuit when the AC voltage is applied, obtained when an AC voltage is applied to the circuit configured by 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 between at least one of 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 using a calculation formula corresponding to the circuit.

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