Damage detection device and rolling bearing

Abstract

A damage detection device (10) is for detecting the state of damage of a rolling bearing provided with an inner race (2), an outer race (3), a plurality of rolling elements (4) that are arranged between the raceway surface of the outer race and the raceway surface of the inner race and that are rolled in accordance with rotation of the inner race or rotation of the outer race, or rotations of both the inner and outer races, and a rotary shaft (5) that is rotated integrally with the inner race or the outer race. The damage detection device (10) comprises: a sensor (11); an inclination processing unit (12); and a damage determination unit (13). A direction toward the center of the rotary shaft is defined as a radial direction, a direction along the shaft length of the rotary shaft is defined as an axial direction, the rotational direction of the rotary shaft is defined as a circumferential direction, and a track of the circumferential direction drawn by the center points of the rolling elements when the rolling elements rotate in the circumferential direction is defined as a rolling element rotation track line. The sensor detects the attitudes of the rolling elements. The inclination processing unit calculates inclinations of the rolling elements around a tangent of the rolling element rotation track line passing through the center points of the rolling elements on the basis of measurement data detected by the sensor. The damage determination unit calculates the state of a damage on the basis of the inclinations.

Description

[Technical field]

[0001] The present disclosure relates to a damage detection device that detects damage occurring in a rolling bearing, and the rolling bearing. [Background technology]

[0002] Conventionally, a method is known in which a sensor detects the behavior of any of the four components of a rolling bearing, namely, an inner ring, an outer ring, a rolling element, and a cage, to diagnose the damaged state of the rolling bearing. Patent Document 1 discloses a condition monitoring device for a rolling bearing, which is equipped with a detection unit that detects the axial acceleration of the rolling bearing. The technology described in Patent Document 1 makes it possible to estimate the length of the damaged portion that progresses in the axial direction in the area in contact with the rolling element, based on the feature quantity of the axial acceleration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-92529 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the strength of the axial acceleration detected by the condition monitoring device described in Patent Document 1 varies depending on the operating conditions and holding conditions of the bearing. For example, when the rotation speed is low, there are cases where almost no acceleration occurs. Also, when the axial length of the rotating shaft is long, there are cases where vibrations caused by bending vibrations, tilting, etc. of the rotating shaft other than those caused by damage are included. Thus, the method of detecting the axial acceleration has a problem that it is difficult to estimate the length of the damaged part in the axial direction with high accuracy because it is not possible to detect the acceleration or it detects acceleration including noise or disturbance vibration.

[0005] The present disclosure has been made in consideration of the above, and aims to provide a damage detection device that can calculate the state of a damaged portion without being affected by the operating conditions, holding conditions, etc. of a bearing. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the damage detection device according to the present disclosure is a damage detection device for detecting a state of damage in a rolling bearing including an inner ring, an outer ring, a plurality of rolling elements arranged between the raceway surface of the outer ring and the raceway surface of the inner ring and rolling with the rotation of the inner ring, the rotation of the outer ring, or the rotation of both the inner ring and the outer ring, and a rotating shaft rotating integrally with the inner ring or the outer ring, the damage detection device including a sensor, an inclination processing unit, and a damage determination unit. The direction toward the center of the rotating shaft is defined as the radial direction, the direction along the axial length of the rotating shaft is defined as the axial direction, the rotation direction of the rotating shaft is defined as the circumferential direction, and the circumferential path drawn by the center point of the rolling element when the rolling element rotates in the circumferential direction is defined as the rolling element rotation path line. The sensor detects the attitude of the rolling element. The inclination processing unit calculates a tangent to the rolling element rotation path line that passes through the center point of the rolling element based on the measurement data detected by the sensor. and extends in the circumferential direction at the center point. The damage determination unit calculates the inclination of the rolling element around the tangent line at which the rolling element is struck. The damage determination unit calculates the state of damage based on the inclination. The inclination of the rolling elements is such that, with respect to both axial ends of the rolling elements, one end approaches the inner ring and the other end moves away from the inner ring. Effect of the Invention

[0007] The damage detection device according to the present disclosure has the advantage of being able to calculate the state of a damaged portion without being affected by the operating conditions, holding conditions, etc. of the bearing. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a damage detection device according to a first embodiment. [Diagram 2] FIG. 1 is a diagram showing an example of the configuration of a damage detection device according to a first embodiment. [Diagram 3] A diagram showing an example of the change in rolling element inclination and damaged shaft length over operating time in a rolling bearing. [Figure 4]FIG. 1 shows an example of the change in the amount of movement of rolling elements, the damaged circumferential length, and the damaged axial length over the course of operating time in a rolling bearing. [Diagram 5] FIG. 13 is a diagram showing an example of the configuration of a damage detection device according to a third embodiment. [Figure 6] A diagram showing an example of the change in damaged shaft length, rolling element inclination, and first derivative of rolling element inclination over the course of operating time in a rolling bearing. [Figure 7] FIG. 13 is a diagram showing an example of the configuration of a damage detection device according to a fourth embodiment. [Figure 8] FIG. 13 is a diagram showing an example of the configuration of a damage detection device according to a fifth embodiment. [Figure 9] FIG. 13 is a diagram showing an example of the configuration of a damage detection device according to a fifth embodiment. [Figure 10] FIG. 13 is a diagram showing an example of the configuration of a damage detection device according to a sixth embodiment. [Figure 11] FIG. 23 is a diagram showing an example of the configuration of a damage detection device according to a seventh embodiment. [Figure 12] FIG. 13 is a diagram showing an example of a hardware configuration of a control unit of the damage detection device according to the first to seventh embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Damage detection devices and rolling bearings according to embodiments of the present disclosure will be described in detail below with reference to the drawings.

[0010] Embodiment 1 A damage detection device according to the first embodiment will be described. FIG. 1 and FIG. 2 are diagrams showing an example of the configuration of the damage detection device according to the first embodiment. FIG. 1 shows a cross section of the rolling bearing 1 that passes through the rotating shaft 5 and is parallel to the rotating shaft 5. FIG. 2 shows a cross section of the rolling bearing 1 perpendicular to the rotating shaft 5, and corresponds to the II-II cross section of FIG. 1. In FIG. 1 and FIG. 2, the up-down direction of the paper corresponds to the up-down direction of the vertical direction. That is, the axis of the rotating shaft 5 is assumed to extend in the horizontal direction. Also, in FIG. 2, the rotating shaft 5 is assumed to rotate counterclockwise. Furthermore, the same applies to the following cross-sectional views similar to FIG. 1 and FIG. 2. In the following description, the direction parallel to the axis of the rotating shaft 5, that is, the direction along the axial length of the rotating shaft 5, may be simply referred to as the axial direction or axial direction. Also, the radial direction centered on the axis, that is, the direction toward the center of the rotating shaft 5, may be simply referred to as the radial direction. The circumferential direction centered on the axis, that is, the rotation direction of the rotating shaft 5, may be simply referred to as the circumferential direction.

[0011] A damage detection device 10 according to a first embodiment detects a state of damage in a rolling bearing 1 shown in FIG. 1 and FIG. 2, which is an object of damage detection. The rolling bearing 1 includes an inner ring 2, an outer ring 3, rolling elements 4, and a rotating shaft 5. The inner ring 2 and the outer ring 3 are cylindrical. The outer ring 3 is arranged concentrically with the inner ring 2 on the outside. The rolling elements 4 are arranged between a raceway surface, which is the inner peripheral surface of the outer ring 3, and a raceway surface, which is the outer peripheral surface of the inner ring 2, and roll with the rotation of the inner ring 2, the rotation of the outer ring 3, or the rotation of both the inner ring 2 and the outer ring 3. A plurality of rolling elements 4 are arranged between the inner ring 2 and the outer ring 3. The rotating shaft 5 rotates integrally with the inner ring 2 or the outer ring 3.

[0012] In the following embodiment, a configuration is shown in which the inner ring 2 rotates integrally with the rotating shaft 5 and the outer ring 3 is fixed, but the rolling bearing 1 may also be configured in such a way that the inner ring 2 is fixed and the outer ring 3 rotates, or in such a way that both the inner ring 2 and the outer ring 3 rotate. The damage detection device 10 according to embodiment 1 can be permanently installed in various rotating devices such as the rolling bearing 1 and electric motors equipped with the rolling bearing 1, or can also be temporarily installed as a portable device.

[0013] Here, we will briefly explain the outline of the occurrence of the damaged part 21 in the rolling bearing 1 when the rotating shaft 5 rotates counterclockwise on the paper together with the inner ring 2 as shown in Fig. 2. In this case, the multiple rolling elements 4 in contact with the raceway surface of the inner ring 2 roll clockwise on the paper around the center point 4C of the rolling elements 4 as the inner ring 2 rotates, and rotate counterclockwise on the paper around the central axis of the rotating shaft 5 between the inner ring 2 and the outer ring 3. When the load on the inner ring 2 due to the load of the rotating shaft 5 or the like acts vertically downward, most of the load from the rotating shaft 5 is transmitted to the raceway surface of the outer ring 3 via the raceway surface of the inner ring 2 and the raceway surfaces of the rolling elements 41, 42, 43, etc. located vertically below the rotating shaft 5. When the rotating shaft 5 is stationary, the position and magnitude of the load generated on each of the inner ring 2, the outer ring 3, and the rolling elements 4 do not change. However, while the rotating shaft 5 is rotating, the position and magnitude of the load change periodically as the inner ring 2 and rolling elements 4 rotate, and repeated stress loads act on the raceway surface. This repeated stress load causes cracks to develop from the inside, starting from impurities inside the material, and reach the surface, causing internal spalling damage in which the surface layer peels off in a scale-like pattern. This internal spalling damage occurs earlier the longer the operating time, bearing load, rotation speed, etc.

[0014] Furthermore, if insufficient lubrication of the raceway surface due to grease deterioration or leakage occurs, causing abnormal slippage between the rolling elements 4 and the inner ring 2 and outer ring 3, the raceway surface may be damaged earlier. As an example, surface-originating spalling damage, in which part of the surface layer peels off in a scale-like pattern, or wear damage may occur.

[0015] According to findings obtained from bearing tests carried out by the inventors, particularly high loads are generated at the axial end positions of the rolling elements 4 due to bending vibration of the rotating shaft 5, axial tilt due to the influence of disturbance vibration, fluttering of the rolling elements 4, etc., and therefore initial damage is highly likely to occur at the axial end positions. In addition, after the initial damage occurs, it is considered that the damaged part 21 expands through a first stage in which the damaged part 21 expands and grows in the axial direction from the damaged part 21 to the rolling element axial length RL, which is the axial length of the rolling elements 4, and then a second stage in which the damaged part 21 expands and grows in the circumferential direction. In addition, based on operation data of various rotating machine products using the rolling bearing 1, the inventors have concluded that in the second stage in which the damaged part 21 expands and grows in the circumferential direction, the vibration or noise has already exceeded the upper limit, and in many cases, damage to peripheral parts such as gears has been caused by the bearing damage. Furthermore, the inventors have also come to the conclusion that by detecting the damaged portion 21 of the rolling bearing 1 in the first stage when the damaged portion 21 is progressing and expanding in the axial direction, it is possible to ensure long-term stable operation of the entire rotating machinery product.

[0016] The damage detection device 10 in embodiment 1 can constantly calculate the damage state, such as the damage axial length AL, which is the axial length of the damaged area 21, even in the early first stage of damage when the damaged area 21 is expanding and progressing in the axial direction.

[0017] The damage detection device 10 according to the first embodiment includes a sensor 11 and a control unit 15.

[0018] The sensor 11 detects the attitude of the rolling element 4. It is preferable that the sensor 11 is capable of detecting a change in attitude of the rolling element 4 due to the influence of the inclination D of the rolling element 4 in a cross section in the axial direction.

[0019] The control unit 15 has a tilt processing unit 12 and a damage determination unit 13. The tilt processing unit 12 calculates the tilt D of the rolling element 4. The circumferential trajectory drawn by the center point 4C of the rolling element 4 when the rolling element 4 rotates in the circumferential direction is defined as the rolling element rotation trajectory line 6. The tilt processing unit 12 calculates the tilt D of the rolling element 4 about a tangent line that is a tangent line to the rolling element rotation trajectory line 6 and passes through the center point 4C of the rolling element 4, based on the measurement data detected by the sensor 11.

[0020] The damage determining unit 13 calculates the damage state including the damaged axial length AL based on the inclination D of the rolling element 4.

[0021] As shown in FIG. 1, in the first stage where the damaged portion 21 develops and expands in the axial direction vertically below the rotating shaft 5, if the damaged axial length AL is smaller than the rolling body axial length RL, the rolling body 41 gets caught in the axially asymmetric damaged portion 21 and tilts. The sensor 11 measures information related to the attitude of the rolling body 41, including the tilt D, and outputs the measurement data, which is the measurement result, to the tilt processing unit 12. The tilt processing unit 12 calculates the tilt D of the rolling body 41 based on the measurement data of the sensor 11. The load acting on each rolling body 4 is calculated from the load acting on the rolling bearing 1 and shape data such as the dimensions of the rolling bearing 1. In addition, as a result of the inventors' investigation and measurement of the damage of the rolling bearing 1, it was found that the depth dimension DL of the damaged portion 21 and the damaged circumferential length CL, which is the circumferential length, have the following relationship. In other words, the depth dimension DL of the damaged portion 21 correlates with the depth at which the shear stress is maximum, which is calculated by the Hertzian contact theory using the load and shape data described above. Also, the damaged circumferential length CL of the damaged portion 21 correlates with the Hertzian contact width, which is similarly calculated by the Hertzian contact theory. By obtaining the inclination D of the rolling element 4 in addition to the shape data described above and the depth dimension DL of the damaged portion 21 and the damaged circumferential length CL of the damaged portion 21, which are calculated by the Hertzian contact theory, the damaged axial length AL can be calculated geometrically.

[0022] That is, the damage determination unit 13 determines the depth and Hertzian contact width at which the shear stress is maximum, which are calculated from the Hertzian contact theory based on the load acting on the rolling bearing 1 and the shape data, calculates the depth dimension DL from the depth at which the shear stress is maximum, and calculates the damaged circumferential length CL from the Hertzian contact width. The damage determination unit 13 then geometrically calculates the damaged axial length AL using the depth dimension DL and damaged circumferential length CL of the damaged portion 21 and the inclination D of the rolling element 4.

[0023] Fig. 3 is a diagram showing an example of the transition of the inclination of the rolling elements and the damaged axial length over the operating time of a rolling bearing. In this diagram, the horizontal axis represents the operating time, and the vertical axis represents the inclination D of the rolling elements 4 and the damaged axial length AL. After the initial damage occurs at time T11, the damaged portion 21 progresses in the axial direction over time, and after time T12 when the damaged axial length AL reaches the rolling element axial length RL, the damage does not progress any further and remains constant.

[0024] While the damaged axial length AL is increasing, the inclination D of the rolling element 4 increases until it reaches the determined damaged axial length AL. After the determined damaged axial length AL is reached, the inclination D of the rolling element 4 decreases. This is thought to be because the axial symmetry of the damaged portion 21 is restored as the damaged portion 21 progresses in the axial direction. Then, when the damaged axial length AL reaches the rolling element axial length RL, the damaged portion 21 becomes axially symmetrical, and the inclination D of the rolling element 4 returns to the initial inclination D before the damage occurred.

[0025] The damage determination unit 13 performs a process of calculating the damage shape, such as the damaged axial length AL, from the inclination D of the rolling element 4 described above. That is, the damage determination unit 13 calculates the damaged axial length AL of the damage as a damage state from the inclination D when the rolling element 4 rotates in the circumferential direction based on the measurement data of the sensor 11. The damage determination unit 13 can also calculate the damage state and remaining life of the rolling bearing 1 based on the calculated damage shape. In the conventional technology, the damage shape could not be calculated accurately because the diagnosis was based on the axial acceleration, which is affected by other disturbances such as the rotation speed of the rotating shaft 5, bending vibration, inclination, and bearing holding conditions. However, in the first embodiment, by measuring the inclination D when the rolling element 4 gets stuck in the damaged portion 21 instead of the axial acceleration, the damage shape can be calculated geometrically with high accuracy while excluding the influence of other disturbances.

[0026] Here, the effects of the first embodiment compared to the conventional technology will be described. In the configuration of a condition monitoring device for a rolling bearing 1 of the conventional technology, the axial force decreases as the rotation speed decreases, making it impossible to extract the axial acceleration. The rotation speed is low during start-up and stop, during manual rotation during maintenance inspection, low-speed rotating equipment, and the like. Conversely, in the configuration of a condition monitoring device for a rolling bearing 1 of the conventional technology, the disturbance vibration increases as the rotation speed increases, and the axial acceleration caused by damage is buried in the disturbance vibration, making it difficult to detect the axial acceleration.

[0027] On the other hand, in the first embodiment, it is possible to stably detect the inclination D of the rolling element 4 regardless of the rotation speed. In particular, in an environment where the rotation speed is low or stopped, it is possible to calculate with high accuracy the damaged shape that could not be detected by the axial acceleration. In addition, in the conventional technology, the damaged axial length AL could only be calculated with high accuracy at the timing of the inflection point of the axial acceleration. However, in the first embodiment, the absolute value of the damaged axial length AL can be calculated geometrically from the absolute value of the inclination D of the rolling element 4, so that it is possible to constantly calculate the damaged shape and damaged state, such as the damaged axial length AL, regardless of the timing of the inflection point.

[0028] Furthermore, when the inclination D of the rolling element 4 is greater than a predetermined value, the damage determination unit 13 can determine that the damaged axial length AL is in a length range determined as a range in which damage progresses at an accelerated rate. In one example, as shown in Fig. 3, when the inclination D of the rolling element 4 is greater than a predetermined value A, it can be seen that the damaged axial length AL is in a range of B1 to B2. When the inclination D of the rolling element 4 becomes smaller than the predetermined value A again, the damaged axial length AL reaches B2, and in many cases the damaged axial length AL accounts for more than half of the rolling element axial length RL, and the damage progress rate accelerates due to the extreme concentration of stress. Therefore, if the damage determination unit 13 detects an abnormality when the inclination D of the rolling element 4 becomes larger than a predetermined value A, more specifically, if it determines from the value of the inclination D of the rolling element 4 whether the damaged axial length AL is within the length range in which damage is considered to progress at an accelerated rate, it becomes possible to prevent accelerated progression of damage to the rolling bearing 1 and accelerated induction of serious failures of the rolling bearing 1, peripheral equipment, and rotating equipment using the rolling bearing 1.

[0029] As described above, in the first embodiment, the damage detection device 10 includes a sensor 11 that measures the attitude of the rolling element 4, an inclination processing unit 12 that calculates the inclination D of the rolling element 4 around a tangent line that is a tangent line of the rolling element rotation trajectory line 6 and passes through the center point 4C of the rolling element 4 based on the measurement data measured by the sensor 11, and a damage determination unit 13 that calculates the damage state based on the inclination D of the rolling element 4. With this configuration, the shape of the damaged portion 21 can be geometrically calculated from the inclination D of the rolling element 4 when it is stuck in the damaged portion 21, and the damaged state can be calculated with high accuracy. In addition, since it is a geometric calculation method, it is not easily affected by the operating conditions and holding conditions of the rolling bearing 1, and the state of the damaged portion 21 can be calculated with high accuracy at all times. In other words, in the first embodiment, the state of the damaged portion 21, specifically, the damaged shape and damaged state such as the damaged axial length AL of the rolling bearing 1 can be calculated with high accuracy at all times without being affected by the operating conditions and holding conditions of the rolling bearing 1.

[0030] Embodiment 2 A damage detection device 10 according to embodiment 2 will be described. The damage detection device 10 according to embodiment 2 has the same configuration as that of embodiment 1. Below, differences from embodiment 1 will be described with reference to Figs. 1 and 2 of embodiment 1.

[0031] 1 and 2, the rolling element 4 is inclined when the raceway surface of the rolling element 4 is located within the range of the damaged circumferential length CL. When the rolling element 4 rotates in the circumferential direction and is stuck in the damaged portion 21, the inclination D of the rolling element 4 increases more than a predetermined inclination, and at the moment of the rolling element 4 leaving the damaged portion 21, the inclination D of the rolling element 4 decreases more than the predetermined inclination. In the second embodiment, the damage determination unit 13 calculates the damaged circumferential length CL based on the measurement data of the sensor 11 from the amount of circumferential movement of the rolling element 4 within a fluctuation time, which is the time from when the inclination D increases more than a predetermined inclination when the rolling element 4 rotates in the circumferential direction to when it decreases more than the predetermined inclination.

[0032] Fig. 4 is a diagram showing an example of the transition of the movement amount of a rolling element, the damaged circumferential length, and the damaged axial length over the operating time of a rolling bearing. In this diagram, the horizontal axis indicates the operating time, and the vertical axis indicates the movement amount of the rolling element 4, the damaged circumferential length CL, and the damaged axial length AL. As shown in Fig. 4, it can be seen that the time rate of change of the damaged circumferential length CL roughly coincides with the time rate of change of the movement amount of the rolling element 4. Therefore, the damaged circumferential length CL can be calculated from the movement amount of the rolling element 4.

[0033] That is, in the second embodiment, the damage determiner 13 calculates the damage circumferential length CL from the amount of circumferential movement of the rolling element 4 based on information on the inclination D of the rolling element 4. Specifically, the damage circumferential length CL is calculated from the amount of movement of the rolling element 4 within a fluctuation time from when the inclination D of the rolling element 4 when the rolling element 4 rotates and moves in the circumferential direction increases beyond a predetermined inclination to when the inclination D of the rolling element 4 decreases beyond the predetermined inclination. Thus, in the second embodiment, the damage determiner 13 calculates the damage circumferential length CL from the actual measurement value of the amount of circumferential movement of the rolling element 4.

[0034] In the second embodiment, the damage determination unit 13 calculates the damaged circumferential length CL from the amount of circumferential movement of the rolling element 4 based on information on the inclination D of the rolling element 4. As a result, a more accurate value obtained by actual measurement is used for the damaged circumferential length CL required to geometrically calculate the damaged axial length AL, rather than a value calculated by the Hertz contact theory. As a result, there is an effect that the damaged axial length AL can be calculated with higher accuracy than in the first embodiment.

[0035] In addition, while the damaged portion 21 is progressing in the axial direction, the rate of progression of the damaged portion 21 in the circumferential direction is slow, but since there is a certain correlation that the progression in the circumferential direction also progresses along with the progression in the axial direction, the damaged axial length AL can be calculated from the damaged circumferential length CL. By utilizing this correlation, the damage determination unit 13 can also calculate the damaged axial length AL from the amount of movement of the rolling element 4 in the circumferential direction. In other words, the damage determination unit 13 can determine that the damaged axial length AL has reached a predetermined length when the amount of movement of the rolling element 4 is greater than a predetermined distance. Alternatively, it is shown that the damage determination unit 13 can determine how long the damaged axial length AL is from the amount of movement of the rolling element 4. In one example, the damage determination unit 13 can determine that the damaged axial length AL has already reached the rolling element axial length RL when the amount of movement of the rolling element 4 is greater than the radius of the rolling element 4. In other words, the damage determination unit 13 can determine whether the damaged axial length AL has reached the rolling element axial length RL from the amount of movement of the rolling element 4.

[0036] Embodiment 3 A damage detection device 10 according to embodiment 3 will be described. Fig. 5 is a diagram showing an example of the configuration of the damage detection device according to embodiment 3. Fig. 5 shows a cross section of a rolling bearing 1 passing through a rotating shaft 5 and parallel to the rotating shaft 5. Note that the same components as those in embodiment 1 are given the same reference numerals and their description will be omitted.

[0037] 5, in the damage detection device 10 of the third embodiment, the control unit 15 further includes a tilt storage unit 14. The tilt storage unit 14 stores, in chronological order, the tilt D of the rolling element 4 calculated by the tilt processing unit 12 based on the measurement data of the sensor 11. In other words, the tilt storage unit 14 stores the change in the tilt D of the rolling element 4 over time.

[0038] In embodiment 3, the damage determination unit 13 calculates the first-order differential value of the inclination D of the rolling body 4, which is the rate of change of the inclination D of the rolling body 4 over time, based on the time-series values ​​of the inclination D stored in the inclination memory unit 14, and determines the damage state from the first-order differential value of the inclination D.

[0039] Fig. 6 is a diagram showing an example of changes in the damaged axial length, the inclination of the rolling elements, and the first derivative of the inclination of the rolling elements over the operating time of a rolling bearing. In this diagram, the horizontal axis represents operating time, and the vertical axis represents the inclination D of the rolling elements 4, the first derivative of the inclination D of the rolling elements 4, and the damaged axial length AL.

[0040] As shown in FIG. 6, when the first-order differential value of the inclination D of the rolling element 4 is larger than the determined positive value a, it can be determined that the damaged axial length AL is within the range where damage is said to progress at an accelerated rate, that is, within the range of b1 to b2. When the damaged axial length AL reaches b2, the damaged axial length AL often occupies more than half of the rolling element axial length RL, and stress is extremely concentrated, accelerating the rate of damage progression. Using this, the damage determination unit 13 detects an abnormality when the first-order differential value of the inclination D of the rolling element 4 is larger than the determined positive value a, or determines whether the damaged axial length AL is within the range where damage is said to progress at an accelerated rate from the first-order differential value of the inclination D of the rolling element 4. This not only makes it possible to grasp the degree of damage to the rolling bearing 1, but also makes it possible to prevent accelerated damage to the rolling bearing 1 and accelerated induced serious failures of the rolling bearing 1, peripheral equipment, and rotating equipment using the rolling bearing 1.

[0041] At the time T31 when the first derivative of the inclination D of the rolling element 4 turns from a positive value to a negative value, it can be determined that the damaged axial length AL has reached the specified magnitude b2. At this time, the damaged axial length AL often accounts for more than half of the rolling element axial length RL, and it is considered that the stress is extremely concentrated as described above, accelerating the damage progression speed. For this reason, the same effect can be obtained by detecting an abnormality when the first derivative of the inclination D of the rolling element 4 turns from a positive value to a negative value, or by determining that the damaged axial length AL has reached the length range where damage progression is considered to accelerate.

[0042] Furthermore, at the time T32 when the first-order differential value of the inclination D of the rolling element 4 becomes lower than the predetermined lower limit c, it can be determined that this is the timing when the damaged axial length AL reaches the rolling element axial length RL. At this time, it is the timing when the damaged portion 21 progresses in the circumferential direction to the second stage, and it can be determined that the vibration or noise has reached the upper limit and that the bearing damage has begun to cause damage to the surrounding parts such as gears. Furthermore, since the absolute value of the first-order differential value of the inclination D of the rolling element 4 becomes smaller than the predetermined value d thereafter, it can be determined that the damaged axial length AL is maintained at the rolling element axial length RL after reaching it. At this time, it can be determined that the damaged portion 21 has already progressed to the second stage when it progresses in the circumferential direction, and that the vibration or noise has already exceeded the upper limit and that the bearing damage has begun to cause damage to the surrounding parts such as gears.

[0043] Furthermore, the inclination D of the rolling element 4 changes continuously over time, but the inclination D of the rolling element 4 changes in an inflection manner over time. For this reason, by using the inclination D of the rolling element 4 stored in time series and detecting the timing of the inflection using the first-order differential value of the inclination D of the rolling element 4, it is possible to calculate the damaged axial length AL within a specified range with higher sensitivity.

[0044] As described above, the damage detection device 10 of the third embodiment further includes a tilt storage unit 14 that stores the tilt D of the rolling element 4 in chronological order, and the damage determination unit 13 determines the state of damage using the first-order differential value of the tilt D of the rolling element 4, which is the rate of change over time of the tilt D of the rolling element 4. This makes it possible to calculate the state of damage more sensitively and accurately.

[0045] Embodiment 4 A damage detection device 10 according to embodiment 4 will be described. Fig. 7 is a diagram showing an example of the configuration of the damage detection device according to embodiment 4. Fig. 7 shows a cross section of a rolling bearing 1 perpendicular to a rotating shaft 5. Note that the same components as those in embodiment 1 are given the same reference numerals and their description will be omitted.

[0046] 7, the rolling bearing 1 further includes a housing 7 connected to the rolling bearing 1. The housing 7 covers the inner ring 2 and the outer ring 3 with the rolling elements 4 sandwiched between their raceway surfaces. In one example, the housing 7 is fixed to the outer periphery of the outer ring 3.

[0047] The circumferential pitch angle on the rolling element rotation trajectory line 6 connecting the center points 4C of two rolling elements 4 adjacent in the circumferential direction is defined as the rolling element pitch angle CI. The angle in the rotation direction of the rotating shaft 5, which indicates the circumferential position, is defined as 0 degrees when it is the circumferential position of the upper end of the rotating shaft 5 on the opposite side to the load direction, 180 degrees when it is the circumferential position of the lower end in the load direction, and 360 degrees when it is the circumferential position of the upper end. The central axis of the rotating shaft 5 has an angle with respect to the load direction, and at least one of the sensors 11 is located within a range from (180-CI) degrees, which is 180 degrees minus the rolling element pitch angle CI, to (180+CI) degrees, which is 180 degrees plus the rolling element pitch angle CI, and is provided on the inner ring 2 or outer ring 3 of the rolling bearing 1 or the housing 7 connected to the rolling bearing 1.

[0048] Damage occurring on the raceway surface of the inner ring 2, the outer ring 3, or the rolling element 4 is highly likely to occur on the contact surface when the rolling element 41 located vertically below the inner ring 2, or the rolling element 4 comes into contact with the outer ring 3, which is fixed to the housing 7, and the sensor 11 must be disposed at the position where the damage occurs. In the fourth embodiment, the sensor 11 is disposed within a range from (180-CI) degrees, which is an angle obtained by subtracting the rolling element pitch angle CI from 180 degrees, to (180+CI) degrees, which is an angle obtained by adding the rolling element pitch angle CI to 180 degrees. By disposing the sensor 11 within this range, the effect of reliably detecting the damaged portion 21 can be obtained with a minimum number of sensors 11. In addition, the inner ring 2, which rotates integrally with the rotating shaft 5, and the rolling element 4, which rotates with the rotation of the inner ring 2, can be moved by rotating the rotating shaft 5, for example. Therefore, it is possible to move the damaged position of the inner ring 2 which rotates integrally with the rotating shaft 5, or the rolling elements 4 which rotate with the rotation of the inner ring 2, within a range from (180-CI) degrees, which is an angle obtained by subtracting the rolling element pitch angle CI from 180 degrees, to (180+CI) degrees, which is an angle obtained by adding the rolling element pitch angle CI to 180 degrees. In other words, damage to the inner ring 2 or the rolling elements 4 can also be reliably detected with a minimum number of sensors 11. For this reason, in the damage detection devices 10 shown in the first to third embodiments, it is preferable that the sensors 11 are provided within a range from (180-CI) degrees, which is an angle obtained by subtracting the rolling element pitch angle CI from 180 degrees, to (180+CI) degrees, which is an angle obtained by adding the rolling element pitch angle CI to 180 degrees.

[0049] In the fourth embodiment, the installation position of the sensor 11 is within a range from (180-CI) degrees, which is an angle obtained by subtracting the rolling element pitch angle CI from 180 degrees, to (180+CI) degrees, which is an angle obtained by adding the rolling element pitch angle CI to 180 degrees. This allows the detection of the rolling element 41 located vertically below where the load, which is likely to cause damage, is maximum, and therefore the effect of reliably detecting damage can be obtained with a minimum number of sensors 11. In addition, the inner ring 2 that rotates integrally with the rotating shaft 5 and the rolling element 4 that rotates with the rotation of the inner ring 2 can be moved to the installation position of the sensor 11 by rotating the rotating shaft 5, so that damage to the inner ring 2 that rotates integrally with the rotating shaft 5 and the rolling element 4 that rotates with the rotation of the inner ring 2 can also be detected with a minimum number of sensors 11.

[0050] Embodiment 5. A damage detection device 10 according to embodiment 5 will be described. Fig. 8 and Fig. 9 are diagrams showing an example of the configuration of the damage detection device according to embodiment 5. Fig. 8 and Fig. 9 show a cross section of a rolling bearing 1 passing through a rotating shaft 5 and parallel to the rotating shaft 5. Note that the same components as those in embodiment 1 are given the same reference numerals and their description will be omitted.

[0051] The sensor 11 described in the first to fourth embodiments detects position information including displacement information in the axial direction of the rolling element 4 as indicated by the arrow E in Fig. 8 or in the radial direction of the rolling element 4 as indicated by the arrow R in Fig. 9. As the sensor 11 for detecting such axial displacement or radial displacement of the rolling element 4, an eddy current gap sensor, a laser sensor, an infrared sensor, a camera, or the like can be used.

[0052] Since the rolling element 4 is inclined asymmetrically in the axial direction, the axial side surface of the rolling element 4 is displaced in the axial and radial directions in accordance with the inclination D of the rolling element 4. Therefore, by detecting these displacements, it is possible to convert them into the inclination D of the rolling element 4. Basically, the rolling element 4 rotates around the vicinity of the axial center point 4C of the rolling element 4, and the axial displacement becomes larger as the position moves radially away from the center point 4C of the rolling element 4. For this reason, it is desirable to attach the sensor 11 that detects the axial displacement at a position as far away as possible in the radial direction from the center point 4C of the rolling element 4. This improves the accuracy of calculating the inclination D of the rolling element 4, and as a result, the accuracy of calculating the damage state such as the damaged axial length AL also improves.

[0053] Furthermore, two sensors 11 at different radial positions may be arranged on both axial side surfaces of the rolling element 4. By combining the two pieces of axial displacement information, it is possible to accurately determine the rotation center position of the inclination D of the rolling element 4. This allows the inclination processing unit 12 and the damage determination unit 13 to geometrically calculate the damage state of the rolling element 4, such as the inclination D and damaged axial length AL, with high accuracy.

[0054] Furthermore, two sensors 11 for detecting the radial displacement of the rolling element 4 may be arranged on both radial side surfaces. The inclination D of the rolling element 4 can be calculated geometrically with high accuracy using the two radial displacement information and the rolling element axial length RL. Therefore, the damage determination unit 13 can also calculate the damage state such as the damaged axial length AL with high accuracy. These two radial displacements are displacements in opposite radial directions. Therefore, by excluding the influence of noise or disturbance vibration and extracting only the opposite displacement components, the damage state such as the damaged axial length AL can be calculated with high accuracy, and the presence or absence of damage can be easily detected from the early stage of damage.

[0055] Furthermore, by using an eddy current gap sensor that reacts only to metal as sensor 11, the influence of a resin retainer or oil such as grease present around the rolling element 4 can be eliminated and the inclination D of the rolling element 4 can be detected with high accuracy.

[0056] In the fifth embodiment, an eddy current type gap sensor, a laser sensor, an infrared sensor, a camera, or the like is used as the sensor 11, which detects position information including displacement information in the axial direction or radial direction of the rolling element 4. This has the effect of enabling the damage state of the rolling element 4, such as the inclination D and the damaged axial length AL, to be calculated with high accuracy.

[0057] Embodiment 6 A damage detection device 10 according to embodiment 6 will be described. Fig. 10 is a diagram showing an example of the configuration of the damage detection device according to embodiment 6. Fig. 10 shows a cross section of a rolling bearing 1 passing through a rotating shaft 5 and parallel to the rotating shaft 5. Note that the same components as those in embodiment 1 are given the same reference numerals and their description will be omitted.

[0058] In the sixth embodiment, the sensor 11 detects reflected waves of light, laser, sound, etc. from the rolling body 4. In one example, as shown in FIG. 10, the sensor 11 of the damage detection device 10 has a transmitter 11a and a receiver 11b. The transmitter 11a transmits an inspection wave, which is a wave for detecting the state of the rolling body 4, such as light, laser, or sound. The receiver 11b detects a reflected wave of the inspection wave, such as light, laser, or sound, reflected by the rolling body 4. The reflected wave can be made larger by transmitting the inspection wave toward the rolling body 4 by the transmitter 11a. The transmitter 11a and the receiver 11b may be disposed at different positions, or the transmitter 11a and the receiver 11b may be integrally configured.

[0059] When the rolling element 4 is stuck in the damaged portion 21 and tilted, the direction of the reflected wave changes, so the tilt D of the rolling element 4 can be calculated by detecting the change in the direction and intensity of the reflected wave. In addition, since the reflected wave from the rolling element 4 is detected, the influence of other disturbances can be eliminated, and the tilt D of the rolling element 4 can be calculated with high accuracy. Furthermore, the sensor 11 may be arranged so that the receiving portion 11b of the sensor 11 is located on a straight line on which the inspection wave transmitted from the transmitting portion 11a is reflected by the axial side surface of the rolling element 4 when the rolling element 4 reaches an arbitrary tilt D. In this way, it is possible to adjust the intensity of the reflected wave to be maximum at the timing when the rolling element 4 reaches an arbitrary tilt D. In other words, since the intensity of the reflected wave is maximum at an angle corresponding to an arbitrary damage threshold set according to the usage environment, it is possible to calculate the progress of the damage with high accuracy.

[0060] In the sixth embodiment, the sensor 11 includes a transmitter 11a that transmits an inspection wave to the rolling element 4, and a receiver 11b that receives the reflected wave reflected by the rolling element 4. This has the effect of making it possible to calculate the inclination D of the rolling element 4 based on the change in the direction and intensity of the reflected wave, without being affected by other disturbances.

[0061] Embodiment 7 A damage detection device 10 according to embodiment 7 will be described. Fig. 11 is a diagram showing an example of the configuration of the damage detection device according to embodiment 7. Fig. 11 shows a cross section of a rolling bearing 1 passing through a rotating shaft 5 and parallel to the rotating shaft 5. Note that the same components as those in embodiment 1 are given the same reference numerals and their description will be omitted.

[0062] As shown in FIG. 11, the damage detection device 10 according to the seventh embodiment includes a sensor 11c that measures the displacement or acceleration of the rolling element 4 including a radial component at the position of the rolling bearing 1 or the housing 7 connected to the rolling bearing 1, and a sensor 11d that measures the displacement or acceleration of the rolling element 4 including an axial component. That is, the sensor 11 is composed of two sensors 11c and 11d. An acceleration sensor, a mechanical displacement sensor, or the like can be used as such sensors 11c and 11d. In the example of FIG. 11, the sensors 11c and 11d are arranged in the housing 7 near the rolling element 4 above the rotation axis 5 in the vertical direction. The sensor 11c corresponds to the first sensor, and the sensor 11d corresponds to the second sensor.

[0063] When the rolling element 4 is caught in the damaged portion 21 and tilted, the larger the tilt D, the larger the axial component of the impact force acting from the rolling element 4 on the inner ring 2 and the outer ring 3, and the larger the axial component of the displacement or acceleration occurring in the rolling bearing 1 or the housing 7 connected to the rolling bearing 1. Also, the ratio of the axial component to the radial component of the displacement or acceleration becomes larger as the tilt D of the rolling element 4 becomes larger. According to the configuration of the seventh embodiment, the ratio of the displacement or acceleration including the radial component to the displacement or acceleration including the axial component is obtained by the sensor 11c and the sensor 11d. This ratio of the displacement or acceleration is correlated with the tilt D of the rolling element 4. In one example, the ratio of the displacement or acceleration including the radial component to the displacement or acceleration including the axial component is proportional to the tilt D of the rolling element 4. That is, in the seventh embodiment, the inclination processing unit 12 calculates the inclination D of the rolling element 4 from the ratio between the displacement or acceleration including a radial component and the displacement or acceleration including an axial component, based on the measurement data of the sensors 11c and 11d. Then, the damage determination unit 13 can use the calculated inclination D of the rolling element 4 to calculate the damage state of the rolling bearing 1, such as the damaged axial length AL.

[0064] In addition, since the impact force caused by the inclination D of the rolling element 4, which is the source of vibration, is hardly affected by lubrication such as grease, the inclination D of the rolling element 4 can be detected with high accuracy without being affected by oil such as grease present around the rolling element 4.

[0065] Damage detection device 10 of embodiment 7 is provided with sensor 11c for measuring the displacement or acceleration of rolling element 4 including a radial component, and sensor 11d for measuring the displacement or acceleration of rolling element 4 including an axial component, at the position of rolling bearing 1 or housing 7 connected to rolling bearing 1. From the ratio between the displacement or acceleration including a radial component detected by sensors 11c and 11d and the displacement or acceleration including an axial component, the inclination D and the damage state of rolling element 4 can be calculated excluding the influence of the lubricating oil.

[0066] Embodiment 8 A rolling bearing 1 according to embodiment 8 will be described. The rolling bearing 1 of embodiment 8 comprises an inner ring 2, an outer ring 3, a plurality of rolling elements 4 that are arranged between the raceway surface of the outer ring 3 and the raceway surface of the inner ring 2 and roll with the rotation of the inner ring 2, the rotation of the outer ring 3, or the rotation of both the inner ring 2 and the outer ring 3, a rotating shaft 5, and a damage detection device 10 according to any one of embodiments 1 to 7. In other words, the rolling bearing 1 is configured to comprise a damage detection device 10 according to any one of embodiments 1 to 7.

[0067] Generally, in rotating equipment such as an electric motor equipped with a rolling bearing 1, the rolling bearing 1 is subject to the largest load and tends to be damaged first. When the damage to the rolling bearing 1 becomes large, the behavior of the entire rotating equipment including the rotating shaft 5 becomes unstable, leading to damage to peripheral equipment of the rolling bearing 1, the rotating shaft 5, gears and couplings, the stator, the housing 7, the frame, and the like. In the eighth embodiment, by installing a damage detection device 10 for the rolling bearing 1 provided in a rotating equipment such as an electric motor, it is possible to determine not only the damage state of the rolling bearing 1 but also the damage state of the entire rotating equipment. In addition, by early grasping the damage state of the rolling bearing 1 and taking measures against the failure, it is also possible to prevent serious failure of the entire rotating equipment.

[0068] Here, a description will be given of a hardware configuration of the control unit 15 of the damage detection device 10. Fig. 12 is a diagram showing an example of a hardware configuration of the control unit of the damage detection device according to the first to seventh embodiments.

[0069] The control unit 15 can be realized by a control circuit 100 shown in Fig. 12, that is, a processor 101 and a memory 102. An example of the processor 101 is a CPU (also called a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration). An example of the memory 102 is a RAM (Random Access Memory) or a ROM (Read Only Memory).

[0070] The processor 101 reads out and executes a control program stored in the memory 102, which is a program for executing processing in the control unit 15, thereby realizing the functions of the control unit 15. It can also be said that this control program causes a computer to execute a control method for the damage detection device 10 in the control unit 15. The control program executed in the control unit 15 has a modular configuration that modularizes a process for calculating the inclination D of the rolling element 4 from the measurement data acquired from the sensor 11, and a damage determination process for calculating a damage state including a damaged axial length AL of the damaged portion 21 from the inclination D of the rolling element 4, and these are loaded onto the main storage device and generated on the main storage device.

[0071] The memory 102 is used as a temporary memory when the processor 101 executes various processes. In the third embodiment, the memory 102 is used as an inclination storage unit 14 that stores the inclination D of the rolling element 4 in chronological order.

[0072] The control program executed by the processor 101 may be provided as a computer program product stored in a computer-readable storage medium in the form of an installable or executable file. The control program executed by the processor 101 may also be provided to the control unit 15 of the damage detection device 10 via a network such as the Internet.

[0073] Moreover, the control unit 15 may be realized by dedicated hardware. Moreover, the functions of the control unit 15 may be partially realized by dedicated hardware and partially realized by software or firmware.

[0074] In the damage detection device 10 according to any one of the above-mentioned first to eighth embodiments, the inner ring 2 shown in Fig. 1, Fig. 2, Fig. 5, Fig. 7 to Fig. 11 is configured to rotate together with the rotating shaft 5, but the shaft integrated with the inner ring 2 may be fixed in rotation. Also, the outer ring 3 is configured to be fixed to the housing 7, but the outer ring 3 may be configured to rotate together with the rotating shaft 5 provided on the outside thereof. Furthermore, the inner ring 2 and the outer ring 3 may both be configured to rotate together with separate rotating shafts 5.

[0075] In the damage detection device 10 according to any one of the above-mentioned embodiments 1 to 8, the rotating shaft 5, the inner ring 2, and the outer ring 3 shown in Figs. 1, 2, 5, 7 to 11 are originally in a horizontal state without inclination. However, the damage detection device 10 according to any one of the above-mentioned embodiments 1 to 8 can geometrically calculate the damage state such as the damaged shaft length AL from the inclination angle of the rotating shaft 5, the inner ring 2, and the outer ring 3 and the inclination D of the rolling element 4 even in the case where the rotating shaft 5 is inclined with respect to the horizontal direction beforehand, such as a tapered roller bearing, or in the case where the rotating shaft 5 is inclined with respect to the horizontal direction due to alignment at the time of installation or bending vibration during operation. It is also possible to ignore the inclination angle of the rotating shaft 5, the inner ring 2, and the outer ring 3 when it is smaller than a predetermined value. In addition, it is also possible to ignore the influence of the inclination angle of the rotating shaft 5, the inner ring 2, and the outer ring 3 by detecting using an inflection point in a time transition curve of the inclination D of the rolling element 4, or by detecting using a first-order differential value of the inclination D, which is the rate of change of the inclination D of the rolling element 4 over time.

[0076] In the damage detection device 10 according to any of the above-mentioned first to eighth embodiments, the number of sensors 11 shown in Figs. 1, 2, 5, and 7 to 10 is one, but the number of sensors 11 may be two or more. Also, the number of sensors 11 shown in Fig. 11 is two, but the number of sensors 11 may be three or more. Furthermore, the arrangement position or shape of the sensor 11 is not limited to the arrangement position or shape shown in Figs. 1, 2, 5, and 7 to 11.

[0077] In the damage detection device 10 according to any one of the first to eighth embodiments, the number and arrangement of the rolling elements 4 are not limited to those shown in FIGS.

[0078] The damage detection device 10 according to any of the above embodiments 1 to 8 can determine the damage state of a rolling bearing 1, including a rolling bearing 1 to which a lubricant such as grease is supplied, a rolling bearing 1 to which a lubricant such as grease is not supplied, a rolling bearing 1 in rotational operation, and a rolling bearing 1 that is stopped from rotating.

[0079] In this specification, expressions expressing directions such as "axial direction," "radial direction," "circumferential direction," and "linear direction" not only include those directions strictly, but also include directions in which substantially the same function can be obtained. Furthermore, in this specification, the expressions "include," "provide," "includes," and "have" do not mean exclusive expressions that exclude the presence of other components.

[0080] Various exemplary embodiments and examples are described in this disclosure, but the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Thus, countless variations not illustrated are envisioned within the scope of the technology of this disclosure. In one example, this includes a case where at least one component is modified, added, or omitted, and further a case where at least one component is extracted and combined with a component of another embodiment. In addition, the configurations shown in the above embodiments can be combined with other known technologies. do. In other words, the configurations shown in the above embodiments may be partially omitted or modified without departing from the spirit of the invention. [Explanation of symbols]

[0081] 1 rolling bearing, 2 inner ring, 3 outer ring, 4, 41, 42, 43 rolling element, 4C center point, 5 rotating shaft, 6 rolling element rotation trajectory, 7 housing, 10 damage detection device, 11, 11c, 11d sensor, 11a transmitter, 11b receiver, 12 tilt processing unit, 13 damage determination unit, 14 tilt memory unit, 15 control unit, 21 damaged part, AL damaged axial length, CI rolling element pitch angle, CL damaged circumferential length, DL depth dimension, RL rolling element axial length.

Claims

1. A damage detection device for detecting a state of damage in a rolling bearing comprising: an inner ring; an outer ring; a plurality of rolling elements disposed between a raceway surface of the outer ring and a raceway surface of the inner ring and rolling with rotation of the inner ring, rotation of the outer ring, or rotation of both the inner ring and the outer ring; and a rotating shaft rotating integrally with the inner ring or the outer ring, a direction toward the center of the rotating shaft is defined as a radial direction, a direction along the axial length of the rotating shaft is defined as an axial direction, a rotation direction of the rotating shaft is defined as a circumferential direction, and a path in the circumferential direction that is traced by the center point of the rolling body when the rolling body rotates in the circumferential direction is defined as a rolling body rotation path line, A sensor for detecting the attitude of the rolling element; an inclination processing unit that calculates an inclination of the rolling element around a tangent to the rolling element rotation locus line, the tangent passing through a center point of the rolling element and extending in a direction along the circumferential direction at the center point, based on the measurement data detected by the sensor; and a damage determination unit that calculates a state of the damage based on the slope; Equipped with A damage detection device characterized in that the inclination of the rolling element is such that, for both axial ends of the rolling element, one end approaches the inner ring and the other end moves away from the inner ring.

2. The damage detection device according to claim 1, characterized in that the damage determination unit calculates a damage axial length, which is the axial length of the damage, as the state of the damage from the inclination when the rolling element rotates in the circumferential direction based on the measurement data of the sensor.

3. 3. The damage detection device according to claim 2, wherein the damage determination unit determines, from the value of the inclination, whether the damage axial length is within a length range in which the damage is believed to progress at an accelerated rate.

4. The damage detection device according to claim 1, characterized in that the damage determination unit calculates a damage circumferential length, which is the circumferential length of the damage, from the amount of movement of the rolling element within a fluctuation time, which is the time from when the inclination when the rolling element rotates in the circumferential direction increases beyond a predetermined inclination to when the inclination decreases below the predetermined inclination, based on the measurement data of the sensor.

5. The damage detection device according to claim 4 , wherein the damage determination unit calculates a damage axial length, which is the axial length of the damage, from the inclination and the damage circumferential length based on the measurement data of the sensor.

6. The damage detection device according to claim 5, characterized in that the damage determination unit determines, from the amount of movement of the rolling element, whether the damaged axial length has reached the rolling element axial length, which is the axial length of the rolling element.

7. A tilt storage unit that stores a change in the tilt over time, The damage detection device according to claim 1, characterized in that the damage determination unit calculates the state of the damage from a first-order differential value of the slope, which is a rate of change of the slope over time, based on the stored value of the slope memory unit.

8. The damage detection device according to claim 7, characterized in that the damage determination unit determines, from the first-order differential value of the slope, whether a damage axial length, which is the axial length of the damage, is within a length range in which the damage is believed to progress at an accelerated rate.

9. The damage detection device according to claim 7, characterized in that the damage determination unit determines that a damage axial length, which is the axial length of the damage, has reached a length in a range in which the damage is believed to progress at an accelerated rate when a first-order differential value of the slope changes from a positive value to a negative value.

10. The damage detection device according to claim 7, characterized in that the damage determination unit determines that a damage axial length, which is the axial length of the damage, has reached the axial length of the rolling element when a first-order differential value of the slope becomes lower than a predetermined lower limit value.

11. The axial direction is a horizontal direction perpendicular to the vertical direction, a pitch angle in the circumferential direction on the rolling element rotation locus line connecting center points of two rolling elements adjacent in the circumferential direction is defined as a rolling element pitch angle; The angle in the rotation direction of the rotating shaft, which indicates the circumferential position, is defined as 0 degrees for the circumferential position of the upper end portion on the opposite side to the load direction, which is the downward direction of the vertical direction in the radial direction of the rotating shaft, the circumferential position of the lower end portion in the load direction is defined as 180 degrees, and the circumferential position of the upper end portion is defined as 360 degrees. The central axis of the rotation shaft has an angle with respect to the load direction, 2. The damage detection device according to claim 1, wherein at least one of the sensors is located within a range from an angle obtained by subtracting the rolling element pitch angle from 180 degrees to an angle obtained by adding the rolling element pitch angle to 180 degrees, and is attached to a housing connected to the inner ring, the outer ring, or the rolling bearing.

12. 2. The damage detection device according to claim 1, wherein at least one of the sensors is a sensor that detects position information of the rolling element in the axial direction.

13. 2. The damage detection device according to claim 1, wherein at least one of the sensors is a sensor that detects position information of the rolling element in the radial direction.

14. 2. The damage detection device according to claim 1, wherein at least one of the sensors is a sensor that detects a reflected wave of light, laser or sound wave from the rolling element.

15. At least one of the sensors includes a first sensor that measures a displacement or acceleration including a radial component at a position of the rolling bearing or a housing connected to the rolling bearing, and a second sensor that measures a displacement or acceleration including an axial component, 2. The damage detection device according to claim 1, wherein the inclination processing unit calculates the inclination from a ratio of a displacement or acceleration including a radial component to a displacement or acceleration including an axial component.

16. With the inner circle, The outer ring and a plurality of rolling elements disposed between a raceway surface of the outer ring and a raceway surface of the inner ring, the rolling elements rolling with a rotation of the inner ring, a rotation of the outer ring, or a rotation of both the inner ring and the outer ring; a rotating shaft that rotates integrally with the inner ring or the outer ring; A damage detection device according to any one of claims 1 to 15; A rolling bearing comprising:

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