Bearing device

Abstract

To provide a bearing device capable of suppressing deterioration of detection accuracy of sensors of a sensor unit fixed to a bearing ring, even when the bearing ring of a rolling bearing causes traveling wave type creep.SOLUTION: A first bearing ring 4 of a rolling bearing 1 includes an inner peripheral part 4a including a raceway surface 4c, an outer diameter surface 4d along a circumferential direction around a central axis CA, and a flank surface 4h having a radial depth δ relative to the outer diameter surface 4d. The sensor unit 2 fixed to the first bearing ring 4 includes sensors 9b, 9c. Sensors 9b, 9c are arranged within an angular region α around the central axis CA in which the flank surface 4h exists.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a bearing device including a rolling bearing and a sensor unit. [Background technology]

[0002] A conventional bearing device is known in which a sensor for detecting the condition of a rolling bearing is mounted on a substrate to form a sensor-equipped circuit board, the circuit board is held in a holder to assemble it into a sensor unit, and the sensor unit is then fixed to a bearing ring. The condition of a rolling bearing is generally detected by detecting temperature and vibration (Patent Document 1).

[0003] In the load zone where a load is applied to the rolling elements that revolve between the first and second raceways, if the amount of heat generated at the contact points between the rolling elements and the raceways or the lubrication conditions change, the temperature of the rolling bearing will change. For this reason, when measuring the temperature of a rolling bearing, the bearing device is installed in machinery so that the temperature sensor is close to the load zone where the temperature is likely to rise.

[0004] Furthermore, in the load-bearing zone, vibration of the rolling bearing occurs when the raceway vibrates in the direction of the load acting on the rolling bearing (translational vibration), leading to serious surface damage at the contact points between the rolling elements and the raceway. For this reason, when detecting rolling bearing vibration, the bearing device is installed in machinery so that the detection direction set in the vibration sensor matches the vibration direction of the rolling bearing, and so that the vibration sensor is located close to the load-bearing zone. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-307435 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the fit between the raceway of a bearing device and the mating component, such as a housing or shaft of another machine, is loose or if the fit interference is insufficient, creep can occur, causing the raceway to rotate in the same direction as the rolling element's revolution, depending on the load conditions of the rolling bearing. This creep occurs when traveling waves are generated on the outer or inner diameter surface of the raceway, which is the mating surface of the raceway with the mating component, and these traveling waves cause the raceway itself to move. In other words, when the rolling element load acts on the raceway surface of the raceway, the outer or inner diameter surface of the raceway protrudes toward the mating component and undulates directly below the load. As the rolling elements revolve during operation of the rolling bearing, the waviness of the outer or inner diameter surface becomes a traveling wave. This traveling wave attempts to move the mating component in the opposite direction to the revolution of the rolling elements, but is pushed back by the resistance of the mating component, resulting in the raceway rotating in the same direction as the revolution of the rolling elements.

[0007] If the raceway ring experiences the traveling wave creep described above, the sensor of the sensor unit fixed to the raceway ring will move away from the load bearing area, which may result in a decrease in the detection accuracy of the sensor.

[0008] In view of the above background, the problem that the present invention aims to solve is to provide a bearing device that can suppress a decrease in the detection accuracy of a sensor in a sensor unit fixed to a raceway of a rolling bearing, even if the raceway of the rolling bearing experiences traveling wave creep. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention employs Configuration 1, which is a bearing device comprising: a rolling bearing having a first raceway, a second raceway, and a plurality of rolling elements arranged between the first raceway and the second raceway; and a sensor unit fixed to the first raceway and including one or more sensors, wherein the first raceway has an inner circumferential portion and an outer circumferential portion, one of which includes a raceway surface, and the other circumferential portion different from the one circumferential portion includes an outer diameter surface or an inner diameter surface along a circumferential direction around a central axis of the first raceway, and wherein the other circumferential portion of the first raceway further includes a flank surface having a radial depth relative to the outer diameter surface or the inner diameter surface included in the other circumferential portion, and at least one of the sensors is arranged within an angular region around the central axis in which the flank surface exists.

[0010] According to the above-mentioned configuration 1, the outer or inner diameter surface of the other peripheral portion of the first bearing ring, which is opposite to the one peripheral portion including the raceway surface, can be clearance-fitted into a mating member such as a housing or a shaft. This creates a relatively large radial gap between the flank included in the other peripheral portion and the mating member. In an operating environment where a static load is applied to the rolling bearing, if the rolling bearing is installed between the shaft and the housing so that the flank is located in the load bearing area of ​​the rolling bearing, the radial gap prevents contact with the mating member even if the other peripheral portion deforms in a wave-like manner, thereby preventing traveling-wave creep of the first bearing ring. On the other hand, if the flank is not appropriately positioned in the load bearing area when installing the rolling bearing between the shaft and the housing, or if the positional relationship between the flank and the load bearing area is inappropriate, such as in an operating environment where the direction of the load applied to the rolling bearing changes, traveling-wave creep may occur in the first bearing ring. As a result of this creep, the sensor of the sensor unit fixed to the first bearing ring moves circumferentially around the central axis of the first bearing ring. If the creep progresses beyond a certain level, the flank enters the load-bearing zone, forming the radial gap described above. The traveling wave is blocked at the flank, and the creep stops. Therefore, by pre-positioning the sensor within the angular region around the central axis where the flank exists, the creep stops when the sensor is located close to the load-bearing zone, thereby preventing a decrease in the detection accuracy of the sensor. Thus, according to the above-mentioned configuration 1, a bearing device can be provided that can prevent a decrease in the detection accuracy of the sensor of the sensor unit fixed to the bearing ring, even if the bearing ring of the rolling bearing experiences traveling-wave creep.

[0011] In the above configuration 1, configuration 2 can be adopted in which the sensor unit includes a vibration sensor as the sensor.

[0012] According to the above-mentioned configuration 2, when creeping stops, the vibration sensor is located in a position close to the load application zone, which is the vibration generating portion, so that a decrease in the detection accuracy of the vibration sensor can be suppressed.

[0013] In the above configuration 2, configuration 3 can be adopted in which the vibration sensor is arranged in an orientation in which the detection direction set for the vibration sensor coincides with a direction parallel to a radial line extending from the central axis toward the flank surface.

[0014] According to the above-mentioned configuration 3, the deviation between the detection direction of the vibration sensor when creeping stops and the direction of the translational vibration in the load direction applied to the rolling bearing is suppressed, thereby suppressing a decrease in the detection accuracy of the translational vibration.

[0015] In any one of the above configurations 1 to 3, a configuration 4 can be adopted in which the sensor unit includes a temperature sensor as the sensor.

[0016] According to the above configuration 4, when creeping stops as described above, the temperature sensor is located in a position close to the load bearing zone of the rolling bearing, so that it is possible to suppress a decrease in the detection accuracy of the bearing temperature.

[0017] In any one of the above configurations 1 to 4, configuration 5 can be adopted, in which, when the pitch angle between the rolling elements is θ, an angular region around the central axis in which the flank surface exists is in the range of 0.5θ or more and 2θ or less. [Effects of the Invention]

[0018] As described above, by adopting the above configuration 1, the present invention can provide a bearing device that can suppress a decrease in the detection accuracy of the sensor of the sensor unit fixed to the raceway of the rolling bearing, even if the raceway undergoes traveling wave creep. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a side view showing a bearing device according to an embodiment of the present invention in a partially cutaway state; [Figure 2] FIG. 2 is a longitudinal sectional front view showing the bearing device of FIG. 1; [Figure 3]FIG. 2 is a side view illustrating the state in which the bearing device of FIG. 1 is installed between a shaft and a housing; [Figure 4] FIG. 2 is a perspective view showing the bearing device of FIG. 1; [Figure 5] FIG. 4 is a perspective view showing the sensor unit of FIG. 3 with the cover removed. [Figure 6] An exploded perspective view of the sensor unit of FIG. 1. [Figure 7] FIG. 10 is a perspective view showing a main part of a modified example of the bearing device according to the embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE INVENTION A bearing device according to an embodiment of the present invention (hereinafter simply referred to as "this bearing device") will be described with reference to the accompanying drawings.

[0021] As shown in FIGS. 1 and 2, the bearing device includes a rolling bearing 1, a sensor unit 2, and a generator 3.

[0022] Here, the direction along the circumference centered on the bearing central axis of the rolling bearing 1 is referred to as the "circumferential direction," the direction along the bearing central axis is referred to as the "axial direction," and the direction perpendicular to the bearing central axis is referred to as the "radial direction."

[0023] The rolling bearing 1 has a first raceway 4, a second raceway 5, and a plurality of rolling elements 6 arranged between the first raceway 4 and the second raceway 5. These rolling elements 6 are held at equal intervals in the circumferential direction by a cage 7.

[0024] The sensor unit 2 is configured as a unit that incorporates an electric circuit that detects at least one of a physical quantity and a chemical quantity related to the state of the rolling bearing 1 while fixed to the first bearing ring 4 and outputs the detection result to a predetermined destination. The sensor unit 2 has a holder 8 connected to the first bearing ring 4 and a sensor-equipped circuit board 9 attached to the holder 8.

[0025] The generator 3 comprises a magnetic ring 10 fixed to the second bearing ring 5 and a stator 11 facing the magnetic ring 10 across a magnetic gap, and the relative rotational motion between the first bearing ring 4 and the second bearing ring 5 is electromagnetically converted into alternating current by the magnetic ring 10 and the stator 11.

[0026] The rolling bearing 1 is a radial bearing. The rolling bearing 1 is also a standard bearing that complies with a specific standard. Here, a standard bearing refers to a bearing that meets the dimensions specified in an ISO or JIS standard. For example, the dimensions of radial bearings other than tapered roller bearings are specified in ISO15 or JIS B 1512-1.

[0027] As shown in Figure 3, the rolling bearing 1 is arranged between a shaft 100 and a housing 110 of another machine. The first bearing ring 4 is usually arranged as a stationary ring. The second bearing ring 5 is usually arranged as a rotating ring. The first bearing ring 4 is clearance-fitted into the housing 110, which is either the shaft 100 or the housing 110, as a mating member. The second bearing ring 5 is interference-fitted into the shaft 100.

[0028] Shaft 100 rotates relative to housing 110. Housing 110 is stationary with respect to shaft 100 and supports rolling bearing 1 in the radial direction. Rolling bearing 1 supports shaft 100 rotatably with respect to housing 110 and bears a radial load F acting between shaft 100 and housing 110. This bearing device is designed to be a case in which radial load F is a stationary load in one direction.

[0029] 1 and 4, the first bearing ring 4 is an outer ring having an inner peripheral portion 4a and an outer peripheral portion 4b. The inner peripheral portion 4a, which is one of the two peripheral portions 4a, 4b, includes a raceway surface 4c, and the other outer peripheral portion 4b, which is the other peripheral portion, includes an outer diameter surface 4d along the circumferential direction.

[0030] The second bearing ring 5 is an inner ring having an outer circumferential portion including a raceway surface 5a and an inner circumferential portion including an inner diameter surface along the circumferential direction. Each rolling element 6 is a ball that rolls between the raceway surfaces 4c and 5a.

[0031] Although the rolling bearing 1 is shown as a deep groove ball bearing, the rolling bearing 1 is not limited to a deep groove ball bearing and may be changed to various bearings such as an angular contact ball bearing or a self-aligning bearing.

[0032] 2, the center axis CA of the first bearing ring 4 coincides with the center axis of the bearing. The inner peripheral portion 4a of the first bearing ring 4 has a fitting portion 4f that supports the holder 8 in the radial direction at a position on the other axial side (left side in FIG. 2; hereinafter, this other axial side will be simply referred to as the "left side") of a width surface portion 4e that is located at one axial end (the right end in FIG. 2; hereinafter, this one axial side will be simply referred to as the "right side") of both ends that define the axial width of the first bearing ring 4 and to the right of the raceway surface 4c, and a step portion 4g that supports a left-side side surface of the holder 8 in the axial direction at a position on the left side of the fitting portion 4f and to the right of the raceway surface 4c.

[0033] The fitting portion 4f is a portion for positioning the holder 8 and the first bearing ring 4 with a predetermined degree of coaxiality. The fitting portion 4f is formed in the shape of a cylindrical surface along the axial and circumferential directions.

[0034] The step portion 4g is a portion that receives the holder 8 in the axial direction when fitting the holder 8 to the first bearing ring 4, determines the fitting stop position, and regulates the inclination of the holder 8 relative to the radial direction in the fitted state. The step portion 4g protrudes higher in the radial direction toward the second bearing ring 5 than the fitting portion 4f, and is formed in the shape of an annular surface that extends in the radial and circumferential directions.

[0035] A certain distance is maintained between the sensor unit 2 and the rolling elements 6. This distance is set so that the sensor unit 2 and the rolling elements 6 will not come into contact even if there is axial displacement due to clearance inside the rolling bearing 1. The cage 7 is a crown-shaped cage that has a ring portion only on the left side of each rolling element 6. The entire sensor unit 2 is housed within the bearing width of the rolling bearing 1, and is also housed within the range of the cross-sectional height of the rolling bearing 1.

[0036] 1 and 4, the outer peripheral portion 4b of the first bearing ring 4 further includes a flank 4h that divides the outer diameter surface 4d over the entire axial width. The flank 4h has a radial depth δ relative to the outer diameter surface 4d. The radial depth δ corresponds to the radial distance from an imaginary circle tangent to the outer diameter surface 4d to the flank 4h.

[0037] The radial depth δ of the flank 4h is set to be maximum at the center of the circumferential length of the flank 4h relative to the diameter of the outer diameter surface 4d, and to become smaller as the position becomes farther from the center in the circumferential direction.

[0038] The first bearing ring 4 is supported in the radial direction by a bearing seat 111 of the housing 110 at its outer diameter surface 4d. As shown in Fig. 3, the flank 4h generates a radial gap g between the flank 4h and the bearing seat 111 of the housing 110. The radial gap g is a space that passes through between the outer circumferential portion 4b of the first bearing ring 4 and the bearing seat 111 of the housing 110 in the axial direction.

[0039] The load zone of the rolling bearing 1, in which the rolling elements 6 are subjected to a radial load, extends over approximately half the circumference of the rolling bearing 1. The circumferential center of this load zone is the position where the rolling element load is maximum, and corresponds to the load direction of the radial load F (corresponding to the position on the extension of the arrow of the radial load F in Figure 3). The outer circumferential portion 4b of the first bearing ring 4 elastically deforms in a wave-like manner due to the rolling element load acting in this load zone. The radial height of this wave shape is greatest at the circumferential center of the load zone, and decreases the further away from the circumferential center.

[0040] It is preferable that the flank 4h be formed so that a non-contact area can be secured over the entire width between the flank 4h and the bearing seat surface 111 of the housing 110 in the load zone when a predetermined radial load F is applied to the rolling bearing 1. In the case of a radial ball bearing, the radial load is generally applied within a range that satisfies (equivalent load applied to the ball bearing: P / basic dynamic load rating of the ball bearing: C)≦0.4. Therefore, if we assume that the maximum value of the predetermined radial load F mentioned above is P / C=0.4 for the rolling bearing 1, it is generally possible to secure the non-contact area mentioned above.

[0041] The maximum radial depth δ of the flank 4h shown in FIG. 1 is set to be greater than the maximum radial height of the corrugation in the load zone of the rolling bearing 1 when the rolling bearing 1 is subjected to the aforementioned maximum radial load F (see also FIG. 3). The radial depth δ of the flank 4h gradually decreases from the center of the circumferential length of the flank 4h toward the outer diameter surface 4d so as not to exceed the aforementioned decrease in the radial height of the corrugation depending on the circumferential position. Note that the radial gap g in FIG. 1 and the radial depth δ in FIG. 3 are exaggerated. In actual corrugation deformation of the outer peripheral portion 4b of the first bearing ring 4, the relative height of the corrugation relative to the outer diameter surface 4d is generally at most a few μm.

[0042] In the illustrated example, as shown in FIGS. 1 and 4 , the flank 4h is formed as a continuous flat surface between both circumferential ends of the arc-shaped outer diameter surface 4d. The circumferential length of the flank 4h is determined by an angular region α about the central axis CA. Here, when the pitch angle between the rolling elements 6 shown in FIG. 1 is θ, the angular region α about the central axis CA in which the flank 4h exists can be set, for example, within the range 0<α≦2θ. This allows the portion of the outer diameter surface 4d located in the load bearing zone to be received by the bearing seat 111 of the housing 110, thereby supporting the first bearing ring 4 in the radial direction and creating the aforementioned radial gap g. Furthermore, to prevent contact between the first bearing ring 4 and the bearing seat 111 of the housing 110 even when the first bearing ring 4 is deflected by the radial load F shown in FIG. 3 , it is preferable to set the angular region α within the range 0.5θ≦α≦θ.

[0043] The first bearing ring 4 is supported radially in the load zone at a contact portion between a portion of the outer diameter surface 4d located within the load zone and the bearing seat surface 111 of the housing 110. Because a radial gap g is formed between the bearing seat surface 111 of the housing 110 and the flank surface 4h of the first bearing ring 4, the radial gap g remains even if the outer peripheral portion 4b of the first bearing ring 4 deforms in a wave-like manner in the load zone of the rolling bearing 1 when the maximum radial load F is applied, and in the angular region where the radial gap g remains, the wave-like deformation portion of the outer peripheral portion 4b cannot come into contact with the bearing seat surface 111 of the housing 110, and the wave-like deformation occurring in the outer peripheral portion 4b does not act as a traveling wave that rotates the first bearing ring 4 in the same direction as the revolution direction of the rolling elements 6. At the contact point between the outer diameter surface 4d and the bearing seat surface 111 in the load-bearing zone, the slight wavy deformation portion of the outer diameter surface 4d comes into contact with the bearing seat surface 111, but the reaction force from the bearing seat surface 111, which is subjected to the slight wavy deformation, is not strong enough to rotate the first raceway 4.

[0044] Therefore, in an operating environment where a static load is applied to the rolling bearing 1, the occurrence of traveling-wave creep in the first bearing ring 4 can be prevented by assembling the rolling bearing 1 between the shaft 100 and the housing 110 so that the flank 4h is located within the load-bearing area of ​​the rolling bearing 1. On the other hand, if the flank 4h is not properly positioned within the load-bearing area when the rolling bearing 1 is installed between the shaft 100 and the housing 110, or if the operating environment is one in which the direction of the load applied to the rolling bearing 1 changes, the first bearing ring 4 may experience traveling-wave creep. If the creep progresses beyond a certain point, the flank 4h enters the load-bearing area, forming the radial gap g described above. The traveling wave is blocked by the flank 4h, and the creep stops. At this point, the phases of the first bearing ring 4 and the sensor unit 2 remain almost unchanged from those shown in FIG. 3.

[0045] The shape of the flank is not limited. For example, the radial depth of the flank may be substantially constant over substantially the entire angular region α shown in FIG. 1 . However, if there is a step at the circumferential end of the flank, creating a linear edge, the contact pressure on the edge will be excessive. To avoid this, the flank may be smoothly connected to the outer diameter surface 4d by a single or multiple curved surfaces so as not to form an edge. For example, the flank may be a substantially arc-shaped flank extending along the axial direction, with the radius of curvature of the substantially arc-shaped surface being larger than that of the outer diameter surface 4d, and the center line (center of curvature) of the substantially arc-shaped surface may be positioned radially offset from the central axis CA.

[0046] In addition, an example has been shown in which the first raceway ring 4 is made of a single metal ring, and the outer diameter surface 4d and the flank surface 4h are machined on the metal surface thereof, but the flank surface may be formed by adhering another material to the metal main ring including the raceway surface. For example, the outer diameter surface and the flank surface may be formed by applying painting, chemical conversion treatment, plating, etc. to the main ring to adhering a coating, solid lubricant film, etc., or the outer diameter surface and the flank surface may be formed by fixing a separate member such as a resin molded part to the main ring.

[0047] Furthermore, the flanks may be formed at multiple locations in the circumferential direction. In this case, when traveling wave creep occurs in the first bearing ring 4, one of the multiple flanks distributed in the circumferential direction reaches the load bearing zone earlier, thereby reducing the amount of creep.

[0048] As shown in Figures 2 and 5, the holder 8 of the sensor unit 2 is made of a seamless magnetic material having a peripheral portion 8a that fits into the fitting portion 4f, an annular side portion 8b that protrudes radially from the left side of the peripheral portion 8a, and a protrusion that protrudes radially from the right side of the peripheral portion 8a. The overall shape of the holder 8 is formed by press-forming an iron-based plate material. The peripheral portion 8a is formed into a cylindrical plate shape that extends in the circumferential direction. The annular side portion 8b is formed into an annular plate shape that extends in the radial direction. The left side surface of the annular side portion 8b contacts the step portion 4g. A circuit board 9 is disposed on the right side surface of the annular side portion 8b.

[0049] The circuit board 9 is a printed circuit board on which the above-mentioned electric circuit is formed. As shown in Fig. 3, the circuit board 9 has a substrate 9a, one or more sensors 9b and 9c mounted on the substrate 9a, a wireless communication circuit 9d mounted on the substrate 9a, and a power supply circuit 9e mounted on the substrate 9a.

[0050] The substrate 9a is a printed wiring board. The substrate 9a is an arc-shaped plate that is short in the radial direction and long in the circumferential direction. Sensors 9b and 9c, a wireless communication circuit 9d, etc. are mounted on the right side of the substrate 9a.

[0051] 1 and 5, the substrate 9a is fixed to the annular side portion 8b by a plurality of screws 13. It is also possible to fix the substrate 9a and the annular side portion 8b by bonding them together using an adhesive, an adhesive sheet, or the like.

[0052] Sensors 9b and 9c each consist of a circuit that converts the aforementioned physical or chemical quantities into an electrical signal. Sensor 9b is a vibration sensor for monitoring the vibration of rolling bearing 1 (hereinafter, sensor 9b will be referred to as "vibration sensor 9b" as appropriate). Sensor 9c is a temperature sensor for monitoring the temperature of rolling bearing 1 (hereinafter, sensor 9c will be referred to as "temperature sensor 9c" as appropriate).

[0053] The vibration sensor 9b may be any sensor capable of detecting bearing vibrations, and may be, for example, an acceleration sensor or an AE (Acoustic Emission) sensor. If an acceleration sensor is used, it is possible to detect radial or axial acceleration in order to monitor the vibration of the rolling bearing 1. If an AE sensor is used, it is possible to detect elastic waves (AE waves) emitted when sound generated when a part of an object, such as a component of the rolling bearing 1, is deformed or damaged, or when an impact is applied.

[0054] The type of vibration sensor 9b is not limited, but for example, a MEMS (Micro Electro Mechanical System) sensor such as a capacitance type, a piezoresistance type, or a heat detection type can be used as the vibration sensor 9b.

[0055] The vibration sensor 9b has a detection direction set. This detection direction is the direction in which the vibration sensor 9b can sense vibrations and convert them into electrical signals, and is determined according to the conversion structure. In general, the detection direction of a vibration sensor is specified as the direction in which the vibration sensor is attached. When attaching the vibration sensor to a desired location, the more appropriately the orientation of the vibration sensor is determined so that the direction of the desired vibration to be detected matches the detection direction of the vibration sensor, the more accurately the vibration to be detected will be applied to the vibration sensing portion of the vibration sensor in the appropriate direction, thereby improving the detection accuracy.

[0056] During operation of the rolling bearing 1 shown in Figure 3, a radial load F applied to the rolling bearing 1 in its load-bearing zone causes translational vibration in which the first bearing ring 4 vibrates in the direction of the radial load F. The vibration sensor 9b is used to detect this translational vibration. The vibration sensor 9b is arranged so that the detection direction set for the vibration sensor 9b coincides with the direction parallel to a radial line L extending from the central axis CA toward the flank face 4h.

[0057] In a static load environment, if this bearing device is installed between the shaft 100 and the housing 110 so that the radial line L and the direction of the radial load F are aligned, traveling wave creep of the first bearing ring 4 is prevented, resulting in good translational vibration detection accuracy. Even if traveling wave creep occurs in the first bearing ring 4 if the orientation of this bearing device is incorrect, the creep will stop when the flank 4h enters the load-bearing zone, and the translational vibration in the direction of the radial load F acting on the rolling bearing 1 will match the detection direction of the vibration sensor 9b. This reduces the deviation between the direction of the translational vibration and the detection direction of the vibration sensor 9b, thereby preventing a decrease in detection accuracy.

[0058] As shown in FIG. 1, in this bearing device, the radial line L intersects with the angular position at the maximum radial depth δ where the traveling wave creep of the first bearing ring 4 is most reliably stopped, i.e., the angular position that bisects the angular region α where the flank surface 4h exists. However, the radial line may intersect with any intermediate angular position within the angular region α.

[0059] The temperature sensor 9c consists of a circuit that converts temperature into an electrical signal. The temperature sensor 9c is positioned axially opposite the raceway surface 4c. The rolling bearing 1 generates heat as it rotates. One of the main causes of this heat is heat generated at the contact point between the rolling elements 6 and the first raceway ring 4. The faster this heat reaches the temperature sensor 9c, the faster and more accurately temperature changes in the first raceway ring 4 can be detected. Therefore, it is advisable to provide a heat conduction path consisting of a solid portion that continues axially from the raceway surface 4c to the circuit board 9, preferably to the temperature sensor 9c. Alternatively, a hole may be formed in the board 9a, and the temperature sensor 9c may be embedded in this hole and placed in contact with the right side surface of the annular side portion 8b.

[0060] Temperature sensor 9c is positioned within angular region α around the central axis in which flank 4h is located. As described above, even if traveling-wave creep occurs in first bearing ring 4, when flank 4h enters the load zone and the creep stops, temperature sensor 9c is in the same angular position as the load zone where the temperature is likely to rise due to the radial load F. This prevents a decrease in the accuracy of bearing temperature detection by temperature sensor 9c.

[0061] 4, an indicator 4i indicating the correct installation direction of this bearing device is provided on the right side surface of the first bearing ring 4. If the rolling bearing 1 is installed between the shaft 100 and the housing 110 so that the direction indicated by the indicator 4i coincides with the direction of the radial load F, traveling wave creep of the first bearing ring 4 can be prevented from the start of installation, and appropriate detection can be performed by the vibration sensor 9b and the temperature sensor 9c.

[0062] 1, in addition to the vibration sensor 9b and temperature sensor 9c, the detection accuracy can be improved by similarly arranging a sensor that detects changes that occur in the load zone of the rolling bearing 1. Note that electronic components including the temperature sensor and vibration sensor may be mounted on the substrate 9a.

[0063] The wireless communication circuit 9d is a communication circuit that converts predetermined information, such as the detection results of the sensors 9b and 9c, into radio waves and radiates them from an antenna. The wireless communication circuit 9d conforms to a predetermined communication protocol and is generally modular.

[0064] The power supply circuit 9 e is a circuit that converts AC power generated by the stator 11 as the magnetic ring 10 rotates into DC power used by the circuit board 9 .

[0065] The magnetic ring 10 is a rotor that generates a rotating magnetic field for the stator 11. The magnetic ring 10 is fixed to the second bearing ring 5. The magnetic ring 10 consists of magnets that are magnetized with alternating north and south poles in the circumferential direction and a core metal that is bonded to the magnets around the entire circumferential direction. The core metal has a flange portion to increase its rigidity. The magnetic ring 10 is fixed to the second bearing ring 5 by press fitting, bonding, or a combination of these. A notch is formed around the entire circumferential direction on the right side of the second bearing ring 5 for locating the flange portion of the magnetic ring 10. The entire magnetic ring 10 is accommodated within the bearing width of the rolling bearing 1 and is also accommodated within the range of the cross-sectional height of the rolling bearing.

[0066] The stator 11 is a stator that guides the magnetic flux emitted from the magnetic ring 10 through a yoke structure and induces an AC voltage in the coil 11a within the yoke structure. The stator 11 is provided in the sensor unit 2 so as to face the magnetic ring 10 with an air gap between them. The yoke structure is formed by axially connecting the annular side portion 8b of the holder 8 and the yoke member 14, as shown in Figures 2, 5, and 6.

[0067] The holder 8 has first claw pole portions 8d that protrude to the right at regular intervals in the circumferential direction from the end of the annular side portion 8b on the second bearing ring 5 side. The yoke member 14 has an annular portion 14a that faces the peripheral portion 8a of the holder 8 at a radial interval, a side peripheral portion 14b that extends radially from the right end of the annular portion 14a toward the second bearing ring 5, and a second claw pole portion 14c that extends to the left at regular intervals in the circumferential direction from the side peripheral portion 14b. The yoke member 14 is made of a magnetic material such as a seamless steel plate. The overall shape of the yoke member 14 is formed by press working.

[0068] The first claw pole portion 8d and the second claw pole portion 14c are arranged in opposite axial directions and alternately arranged in the circumferential direction. A circumferential air gap is formed between the first claw pole portion 8d and the second claw pole portion 14c that are adjacent in the circumferential direction. The first claw pole portion 8d and the second claw pole portion 14c face each other in the radial direction, with an air gap between them and the magnets of the magnetic ring 10.

[0069] 6, the coil 11a is wound around a bobbin 11b and arranged around the entire circumferential direction in a space surrounded by the end of the annular side portion 8b on the second bearing ring 5 side, the side peripheral portion 14b, the annular portion 14a, the first claw pole portion 8d, and the second claw pole portion 14c.

[0070] The magnetic flux emanating from the north pole of the magnetic ring 10 shown in FIGS. 1 and 2 travels from the first claw pole 8d (or the second claw pole 14c), which is a magnetic pole, to the end of the annular side portion 8b on the second bearing ring 5 side (or the side circumferential portion 14b), then travels around the coil 11a to the side circumferential portion 14b (or the end of the annular side portion 8b on the second bearing ring 5 side) via the annular portion 14a, then travels around the coil 11a to the adjacent second claw pole 14c (or the first claw pole 8d), and returns to the south pole of the magnetic ring 10. When the north and south poles of the magnetic ring 10 swap positions with the relative rotation of the first bearing ring 4 and the second bearing ring 5, the direction of the magnetic flux reverses. The alternating magnetic field thus generated generates an alternating voltage at both ends of the coil 11a, at the beginning and end of the winding. While a radial-type claw pole generator is shown as the generator 3, other types of generators are also possible.

[0071] Both ends of the coil 11a are connected to input terminals of a power supply circuit 9e on the substrate 9a shown in Figure 1. The power supplies for the sensors 9b, 9c and the wireless communication circuit 9d are each output terminals of the power supply circuit 9e. This bearing device is capable of performing detection and wireless communication using the circuit substrate 9 with the generator 3 as its power source, making it possible to make the sensor unit 2 wireless. An emergency battery may be mounted on the substrate 9a, or the sensor unit may be modified to be driven solely by the battery.

[0072] The peripheral portion 8a and annular side portion 8b of the holder 8 and the annular portion 14a of the yoke member 14 form an opening for accommodating the circuit board 9. This opening is closed by a cover 15, as shown in FIGS. 1 and 2. The cover 15 is fixed to the circuit board 9 without contacting it. The internal space between the cover 15 and the circuit board 9 is filled with air. The spaces between the cover 15 and the peripheral portion 8a and between the cover 15 and the annular portion 14a may be sealed with a sealant, respectively.

[0073] The cover 15 is made of resin that does not contain metal. Even if the holder 8 and the yoke member 14 are made of metal, the cover 15 is radio wave transparent, so wireless communication using the antenna of the wireless communication circuit 9d is possible. The cover may be made of metal, with a portion of the area facing the antenna made of non-metal (for example, resin). It is also possible to seal the circuit board without using a cover by filling the opening with a sealant.

[0074] In the ring-shaped space radially sandwiched between the first raceway ring 4 and the second raceway ring 5, the circuit board 9, stator 11, and magnetic ring 10 are arranged so as to face each other radially and not overlap in the axial direction, and therefore these can be arranged thinly in the axial direction and provided as a bearing device of the same size as the rolling bearing 1 configured as a standard bearing.

[0075] The means for fixing the sensor unit 2 to the first bearing ring 4 is not particularly limited. Press-fitting the peripheral portion 8a of the holder 8 into the fitting portion 4f is undesirable because it may cause deformation of the holder 8 and the raceway surface 4c. For this reason, in the illustrated example, the holder 8 is loose-fitted to the first bearing ring 4, and the holder 8 and the first bearing ring 4 are welded together. Note that it is also possible to use other fixing means, such as adhesive, in addition to the loose fit or transition fit.

[0076] This bearing device is as described above (see Figures 1 to 4), and comprises a rolling bearing 1 having a first raceway 4, a second raceway 5, and a plurality of rolling elements 6 arranged between the first raceway 4 and the second raceway 5, and a sensor unit 2 fixed to the first raceway 4 and including one or more sensors 9b, 9c, wherein the first raceway 4 has an inner circumferential portion 4a and an outer circumferential portion 4b, and the inner circumferential portion 4a, which is one of the inner circumferential portions 4a and the outer circumferential portion 4b, includes a raceway surface 4c, and the other outer circumferential portion 4b, which is different from the one circumferential portion, includes an outer diameter surface 4d that runs in the circumferential direction around the central axis CA of the first raceway 4.

[0077] In particular, in this bearing device, outer peripheral portion 4b, which is the other circumferential portion of first bearing ring 4, further includes a flank 4h having a radial depth δ relative to an outer diameter surface 4d included in outer peripheral portion 4b, and at least one sensor 9b, 9c is disposed within an angular region α about central axis CA in which flank 4h exists, so that the outer diameter surface 4d of outer peripheral portion 4b is clearance-fitted into a corresponding mating member (bearing seat surface 111 of housing 110), forming a relatively large radial gap g between flank 4h and the mating member. Therefore, in an operating environment in which static loads are applied to rolling bearing 1, if rolling bearing 1 is assembled between shaft 100 and housing 110 so that flank 4h is located within the load application zone of rolling bearing 1, the radial gap g described above will prevent contact with the mating member even if outer peripheral portion 4b deforms in a wave-like manner, and it is possible to prevent traveling-wave creep of first bearing ring 4. On the other hand, even if traveling-wave creep occurs in the first bearing ring 4, once the creep progresses beyond a certain level, the flank 4h enters the load-bearing zone, forming the radial gap g described above. The traveling wave is blocked by the flank 4h, and the creep stops. At this time, because the sensors 9b and 9c are located close to the load-bearing zone, it is possible to suppress a decrease in the detection accuracy of the sensors 9b and 9c. Therefore, this bearing device can be provided as a bearing device that can suppress a decrease in the detection accuracy of the sensors 9b and 9c of the sensor unit 2 fixed to the bearing ring 4, even if the first bearing ring 4 experiences traveling-wave creep.

[0078] Furthermore, in this bearing device, since the sensor unit 2 includes the vibration sensor 9b as a sensor, when the creep stops as described above, the vibration sensor 9b is located in a position close to the load bearing area, which is the vibration generating part, and therefore, a decrease in the detection accuracy of the vibration sensor 9b can be suppressed.

[0079] Furthermore, in this bearing device, the vibration sensor 9b is arranged in an orientation such that the detection direction set for the vibration sensor 9b is aligned with the direction parallel to the radial line L extending from the central axis CA toward the flank 4h. This reduces the deviation between the detection direction of the vibration sensor 9b when creeping stops and the direction of the translational vibration caused by the load F direction applied to the rolling bearing 1, thereby preventing a decrease in the detection accuracy of the translational vibration.

[0080] Furthermore, in this bearing device, since the sensor unit 2 includes a temperature sensor 9c as a sensor, when the creep stops as described above, the temperature sensor 9c is located in a position close to the load-bearing zone of the rolling bearing 1, thereby suppressing a decrease in the detection accuracy of the bearing temperature.

[0081] While this bearing device illustrates an example in which the first bearing ring 4 is an outer ring, the sensor can be similarly disposed when the first bearing ring is an inner ring. In this case, the only requirement is to reverse the radial directionality. For example, as shown in FIG. 7 , an excerpt of the positional relationship between the first bearing ring (an inner ring) and the vibration sensor is as follows: the first bearing ring 4 has an inner peripheral portion 4a and an outer peripheral portion 4b; the outer peripheral portion 4b, which is one of the inner peripheral portion 4a and the outer peripheral portion 4b, includes a raceway surface 4c, a fitting portion, and a step; the inner peripheral portion 4a, which is the other peripheral portion different from the inner peripheral portion 4a, includes an inner diameter surface 4j extending in the circumferential direction around the central axis CA and a flank surface 4h that has a radial depth relative to the inner peripheral portion 4a and divides the inner diameter surface 4j across its entire width; and the sensor 9b included in the sensor unit 2 fixed to the outer peripheral portion 4b is disposed within an angular region α around the central axis. Even in this case, when traveling wave creep of the first bearing ring 4 relative to the shaft (see the figure) stops, the sensor 9b is located in a position close to the load bearing area, making it possible to suppress a decrease in detection accuracy.

[0082] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0083] 1. Rolling bearings 2 Sensor Unit 3. Generator 4 First bearing ring 4a Inner circumference 4b Outer periphery 4c raceway surface 4d outer diameter surface 4h relief face 4j Inner diameter surface 5 Second bearing ring 6 rolling elements 9b Sensor (Vibration Sensor) 9c Sensor (Temperature Sensor) CA center axis L Radial straight line g Radial clearance α angular domain δ radial depth

Claims

1. a rolling bearing having a first raceway, a second raceway, and a plurality of rolling elements disposed between the first raceway and the second raceway; a sensor unit fixed to the first bearing ring and including one or more sensors; In a bearing device, the first raceway ring has an inner peripheral portion and an outer peripheral portion, one of the inner peripheral portion and the outer peripheral portion includes a raceway surface, and the other peripheral portion different from the one peripheral portion includes an outer diameter surface or an inner diameter surface along a circumferential direction around a central axis of the first raceway ring, the other peripheral portion of the first bearing ring further includes a flank having a radial depth relative to the outer diameter surface or the inner diameter surface included in the other peripheral portion, A bearing device, characterized in that at least one of the sensors is disposed within an angular region around the central axis in which the flank exists.

2. The bearing device according to claim 1 , wherein the sensor unit includes a vibration sensor as the sensor.

3. 3. The bearing device according to claim 2, wherein the vibration sensor is arranged so that the detection direction set for the vibration sensor coincides with a direction parallel to a radial line extending from the central axis toward the flank surface.

4. The bearing device according to claim 1 , wherein the sensor unit includes a temperature sensor as the sensor.

5. 4. The bearing device according to claim 1, wherein an angular region around the central axis in which the relief surface exists is in the range of 0.5θ to 2θ, where θ is a pitch angle between the rolling elements.

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