Bearing device with rotation sensor

Abstract

To provide a bearing device with a rotation sensor which can inhibit reduction in detection accuracy caused by combination of a self-aligning function and a magnetic rotation sensor.SOLUTION: A bearing body 14 comprises a bearing having a self-aligning function in which an outer ring 22 moves along an arc-shaped trajectory T whose center is a bearing center C. A rotation sensor 16 comprises a magnetic encoder 44 fixed to one of an inner ring 20 and the outer ring 22 and configured to generate a magnetic field, and a magnetic sensor 52 fixed to the other of the inner ring 20 and the outer ring 22 and configured to detect a magnetic field. The magnetic encoder 44 and the magnetic sensor 52 are spaced along the radial direction of a rotation axis 12 such that axes of the inner ring 20 and the outer ring 22 coincide.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a bearing device with a rotation sensor. [Background technology]

[0002] Conventionally, there has been known a bearing device with a rotation sensor in which a rotation sensor for detecting the rotation state of a rotating shaft is integrally attached to a bearing body that holds the rotating shaft.One example of the detection method of this rotation sensor is a magnetic rotation sensor in which a magnetic generating unit that is fixed to one of the inner and outer rings and generates magnetic field and a magnetic detecting unit that is fixed to the other of the inner and outer rings and detects magnetic field are disposed separately, and the rotation state of the rotating shaft is detected based on the magnetic detection result (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-286266 A [Patent Document 2] JP 2011-127688 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, in large machinery and equipment including elevator hoists, a bearing body having a so-called self-aligning function (or self-centering function) may be used to deal with bending of the rotating shaft due to high load. When this self-aligning function is exercised, one of the inner and outer races (hereinafter, the movable race) moves along an arc-shaped track centered on the center of the bearing. In other words, even if the rotating shaft is at the same angular position, the positional relationship between the magnetic generating unit and the magnetic detecting unit may change depending on the position of the movable race. As a result, a problem occurs in that the detection accuracy of the rotation state decreases.

[0005] The present invention has been made in consideration of these problems, and its object is to provide a bearing device with a rotation sensor that can suppress the decrease in detection accuracy caused by the combination of a magnetic rotation sensor and an automatic alignment function. [Means for solving the problem]

[0006] A bearing device with a rotation sensor in a first aspect of the present invention is a device comprising a bearing body that holds a rotating shaft, and a rotation sensor mounted on the bearing body that detects the rotational state of the rotating shaft, wherein the bearing body comprises a bearing having an automatic centering function in which a movable race, which is either an inner ring or an outer ring, moves along an arc-shaped orbit centered on the bearing center, and the rotation sensor comprises a magnetic generating unit fixed to one of the inner ring and outer ring and generates magnetic field, and a magnetic detecting unit fixed to the other of the inner ring and outer ring and detects magnetic field, and the magnetic generating unit and the magnetic detecting unit are positioned at a distance along the axial direction of the bearing body at a reference position of the movable race.

[0007] In a bearing device with a rotation sensor in a second aspect of the present invention, the rotation sensor further comprises a substrate to which the magnetic detection unit is fixed on its front side, and a cable connected to the rear side of the substrate and arranged to extend along the axial direction of the bearing body.

[0008] In a bearing device with a rotation sensor in a third aspect of the present invention, one of the magnetic generating unit and the magnetic detecting unit is arranged parallel to the radial direction of the rotating shaft, and the other of the magnetic generating unit and the magnetic detecting unit is arranged inclined with respect to the radial direction of the rotating shaft along a direction perpendicular to the arc-shaped orbit.

[0009] In the bearing device with a rotation sensor according to a fourth aspect of the present invention, the rotating shaft is an output shaft of an elevator hoisting machine. Effect of the Invention

[0010] According to the present invention, it is possible to suppress a decrease in detection accuracy caused by the combination of a magnetic rotation sensor and an automatic centering function. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view of a bearing device with a rotation sensor in one embodiment of the present invention. [Diagram 2] FIG. 2 is a partial enlarged view of an area A shown in FIG. [Diagram 3] 3 is a schematic diagram showing the effect of the arrangement of the rotation sensors in FIG. 2. [Figure 4] FIG. 13 is a schematic diagram showing an arrangement relationship of rotation sensors in another example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same reference numerals are used to refer to the same components in each drawing as much as possible, and duplicated description will be omitted.

[0013] [Configuration of bearing device 10] Fig. 1 is a cross-sectional view of a bearing device with a rotation sensor in one embodiment of the present invention (hereinafter, also simply referred to as "bearing device 10") Fig. 2 is a partial enlarged view of region A shown in Fig. 1.

[0014] 1, bearing device 10 is basically composed of a bearing body 14 that has a self-aligning function and holds a rotating shaft 12, and a rotation sensor 16 mounted on bearing body 14. This bearing device 10 is suitable for devices in which bending of rotating shaft 12 or displacement of the assembly position is likely to occur, specifically, large machinery and equipment including elevator hoists.

[0015] The bearing body 14 is a so-called double-row self-aligning roller bearing. Specifically, the bearing body 14 includes an inner ring 20 that holds the rotating shaft 12, an outer ring 22 that has a larger diameter than the inner ring 20, a plurality of rolling elements 24, two cages 26a, 26b, a housing 28, and an oil seal 30. Here, the number of rolling elements 24 is assumed to be 2N (N≧2).

[0016] The 2N rolling elements 24 are arranged in two rows in the axial direction of the bearing body 14. Half of the 2N rolling elements 24 (N rolling elements) are held by one of the cages 26a in a state where they are arranged at approximately equal intervals along the circumferential direction of the bearing body 14. The remaining half of the 2N rolling elements 24 (N rolling elements) are held by the other cage 26b in a state where they are arranged at approximately equal intervals along the circumferential direction of the bearing body 14.

[0017] Each rolling element 24 has a roughly barrel shape, and is provided to be able to roll between the inner ring 20 and the outer ring 22. Specifically, the outer peripheral surface of the rolling element 24 is in rolling contact with the raceway surface 21 of the inner ring 20 and the raceway surface 23 of the outer ring 22. When the bearing body 14 is an outer ring rotating type bearing, the outer ring 22 rotates integrally with the rotating shaft 12 while the inner ring 20 remains fixed to a housing 28 or the like.

[0018] Here, the outer ring 22 functions as a movable raceway ring with a self-aligning function. In this case, a raceway surface 23 is formed so that the center of curvature coincides with the bearing center C, and the outer ring 22 is configured to be movable along an arc-shaped track along the raceway surface 23 relative to the inner ring 20. Note that a reference position B indicates a neutral point of the movable range of the outer ring 22. In other words, when the outer ring 22 is in the reference position B, the axes of both the inner ring 20 and the outer ring 22 are completely aligned.

[0019] The oil seal 30 is a generally annular member that prevents leakage of lubricating oil to reduce frictional force when the rolling elements 24 move. The oil seal 30 is provided axially outward from the position of the cage 26a so as to bridge the inner ring 20 and the outer ring 22. Meanwhile, a rotation sensor 16 is attached in place of the oil seal at a corresponding position of the cage 26b (i.e., in the gap between the inner ring 20 and the outer ring 22).

[0020] 2, the rotation sensor 16 is composed of a first sensor unit 40 fixed to the outer ring 22 and a second sensor unit 50 fixed to the inner ring 20. This rotation sensor 16 detects the change in magnetism that accompanies the relative movement between the inner ring 20 and the outer ring 22, and detects the rotational state of the rotating shaft 12 (e.g., angular position, rotational speed, rotational direction, etc.).

[0021] The first sensor unit 40 is composed of a bracket 42 and a magnetic encoder 44. The first sensor unit 40 is fixed to the outer ring 22 by attaching the annular bracket 44 to the raceway surface 23 of the outer ring 22. The annular magnetic encoder 44 is fixed onto the annular surface of the bracket 42 extending in the radial direction.

[0022] The magnetic encoder 44 functions as a "magnetic generator" that generates magnetism that correlates with the angular position of the rotating shaft 12. The magnetic encoder 44 is made up of annular magnetic rubbers 45, 46 that are each magnetized with multiple poles and arranged concentrically. By slightly shifting the magnetization pitch (angular interval) of the magnetic rubbers 45, 46, the absolute angular position of the rotating shaft 12 can be identified.

[0023] On the other hand, the second sensor unit 50 includes a magnetic sensor 52, a substrate 54, a cable 56, and a bracket 58.

[0024] The magnetic sensor 52 functions as a "magnetic detection unit" that detects magnetism generated by the magnetic encoder 44. The magnetic sensor 52 is, for example, an integrated circuit incorporating a Hall element that detects a magnetic pattern that indicates a change in magnetism over time. As can be seen from Fig. 2, the magnetic encoder 44 and the magnetic sensor 52 are disposed apart along the axial direction of the bearing body 14. Note that "along the axial direction" includes not only the case where the magnetic sensor 52 coincides with the axial direction, but also the case where the magnetic sensor 52 is tilted within a predetermined tolerance range with respect to the axial direction.

[0025] The board 54 is an electronic circuit board that processes the electric signal output from the magnetic sensor 52. The magnetic sensor 52 and electronic components (not shown) are provided on the front side of the board 54. Although not shown, a connector for connecting the cable 56 and a bias magnet that generates a magnetic bias may be provided on the rear side of the board 54.

[0026] The cable 56 is connected to the rear side of the substrate 54, and is wired to extend along the axial direction of the bearing body 14. As a result, driving power is supplied to the substrate 54 through the cable 56. The substrate 54 also outputs, through the cable 56, an electrical signal that indicates the rotational state of the rotating shaft 12 detected by the magnetic sensor 52.

[0027] The substrate 54 and the cable 56 are attached to the inside of an annular bracket 58 having a generally L-shaped cross section. As a result, the second sensor unit 50 is fixed to the seal fitting surface 21s on the outer edge of the raceway surface 21 of the inner ring 20 via the bracket 58.

[0028] [Operation of bearing device 10] The bearing device 10 in this embodiment is configured as described above. Next, the operation of the bearing device 10 will be described with reference to FIGS.

[0029] 1 and 2, as the housing 28 rotates, the first sensor unit 40 of the rotation sensor 16 rotates integrally with the outer ring 22. On the other hand, the second sensor unit 50 of the rotation sensor 16 does not rotate because it is fixed to the inner ring 20. Therefore, the rotation sensor 16 uses magnetism to detect changes in the relative positional relationship between the first sensor unit 40 and the second sensor unit 50 and detects the rotational state of the rotating shaft 12. On the other hand, if the bearing body 14 exhibits a self-aligning function due to bending of the rotating shaft 12 during this rotational motion, the outer ring 22 moves along an arc-shaped trajectory T from a reference position B.

[0030] Fig. 3 is a schematic diagram showing the effect of the positional relationship of the rotation sensor 16 in Fig. 2. For ease of explanation, the positional relationship between the magnetic encoder 44 and the magnetic sensor 52 is exaggerated in this figure compared to Fig. 2.

[0031] Orbit T is an arc-shaped orbit along which the magnetic encoder 44 moves integrally with the outer ring 22. Point P is the position of the magnetic encoder 44 when the outer ring 22 is at reference position B. Point Q is the position of the magnetic encoder 44 when the outer ring 22 moves by angle Δθ. R is the radius of curvature of the orbital surface 23. Here, it is assumed that the positional relationship between the magnetic encoder 44 located at point P and the magnetic sensor 52 is ideal, that is, there is no positional deviation (or offset).

[0032] By geometrical considerations, when θ=0°, the distance between points P and Q is 2R sin(Δθ / 2) , the radial displacement between points P and Q is PQ sin (Δθ / 2) =2R sin 2 (Δθ / 2) Here, since the magnetic encoder 44 and the magnetic sensor 52 are disposed at a distance from each other in the axial direction, the amount of positional deviation caused by the movement of the outer ring 22 is reduced. As a result, even when the outer ring 22 moves along the arc-shaped trajectory T, the relationship between the magnetic detection result by the rotation sensor 16 and the angular position is easily maintained.

[0033] 4 is a schematic diagram showing the arrangement of the rotation sensor 16 in another example. Here, the magnetic sensor 52 is arranged so as to be inclined by φ outward with respect to the radial direction. The inclination angle φ is set, for example, so that the positional deviation amount (|ΔW|) at point P and point Q is approximately equal. By configuring in this way, the positional deviation amount in a specific section on the track T is further reduced.

[0034] Generally speaking, it is considered that the outer ring 22 moves axially forward or backward with approximately the same frequency, with the reference position B as the center of movement. In this case, it is effective to adopt the positional relationship shown in Fig. 3. However, depending on the assembly state and usage conditions of the bearing device 10, there is a possibility that the center of movement of the outer ring 22 may deviate from the reference position B. In this case, it is effective to adopt the positional relationship shown in Fig. 4.

[0035] 4, the magnetic sensor 52 is disposed so as to be inclined outward by φ with respect to the radial direction, but the opposite relationship may also be used. Specifically, the magnetic encoder 44 may be disposed so as to be inclined outward by φ with respect to the radial direction. This configuration also further reduces the amount of positional deviation in a specific section on the track T.

[0036] Alternatively, both the magnetic encoder 44 and the magnetic sensor 52 may be disposed so as to be inclined with respect to the radial direction. In this case, the magnetic encoder 44 may be parallel to the magnetic sensor 52 (i.e., the same inclination angle) or non-parallel to the magnetic sensor 52 (i.e., different inclination angle). In particular, when the magnetic encoder 44 is parallel to the magnetic sensor 52, the position deviation amount at a specific point Q on the trajectory T becomes even smaller.

[0037] [Summary of the embodiment] As described above, the bearing device 10 includes the bearing body 14 that holds the rotating shaft 12, and the rotation sensor 16 that is mounted on the bearing body 14 and detects the rotation state of the rotating shaft 12. The bearing body 14 is a bearing having a self-aligning function in which a movable raceway (here, the outer raceway 22), which is either the inner raceway 20 or the outer raceway 22, moves along an arc-shaped track T centered on the bearing center C. The rotation sensor 16 includes a magnetic generator (here, the magnetic encoder 44) that is fixed to one of the inner raceway 20 and the outer raceway 22 and generates magnetism, and a magnetic detector (here, the magnetic sensor 52) that is fixed to the other of the inner raceway 20 and the outer raceway 22 and detects magnetism. The magnetic encoder 44 and the magnetic sensor 52 are disposed apart from each other along the axial direction of the bearing body 14 in a state in which the axes of the inner raceway 20 and the outer raceway 22 are aligned (i.e., at the reference position B).

[0038] In this way, the magnetic encoder 44 and the magnetic sensor 52 are disposed apart in the axial direction, i.e., in a direction substantially parallel to the arc-shaped orbit T, so that the amount of positional deviation caused by the movement of the outer ring 22 is reduced. This makes it easier to maintain the relationship between the magnetic detection result by the rotation sensor 16 and the angular position even when the outer ring 22 moves along the orbit T. In other words, it is possible to suppress a decrease in detection accuracy caused by the combination of a magnetic rotation sensor and an automatic centering function.

[0039] The rotation sensor 16 may further include a substrate 54 on the front side of which the magnetic sensor 52 is provided, and a cable 56 connected to the rear side of the substrate 54 and extending along the axial direction of the bearing body 14. This allows the tip of the cable 56 to be arranged in a straight line with respect to the rear side of the substrate 54 without being curved, and the storage space for the tip is reduced, thereby making it possible to reduce the size of the rotation sensor 16.

[0040] Furthermore, one of the magnetic encoder 44 and the magnetic sensor 52 (magnetic encoder 44) may be disposed parallel to the radial direction of the bearing body 14, while the other (magnetic sensor 52) may be disposed inclined relative to the radial direction of the bearing body 14 along a direction perpendicular to the arc-shaped orbit T. This makes it possible to reduce the amount of positional deviation in a specific section on the orbit T.

[0041] The rotating shaft 12 may also be the output shaft of an elevator hoist. During operation of the elevator hoist, the rotating shaft 12 is more likely to bend due to radial load, and the automatic centering function is more frequently exercised. This makes the effect of suppressing the deterioration of detection accuracy more pronounced.

[0042] [Variations] The present invention is not limited to the above-described embodiment, and can be freely modified without departing from the spirit and scope of the present invention. Alternatively, the respective configurations may be arbitrarily combined without causing any technical contradiction.

[0043] In the above embodiment, the bearing body 14 is a double-row self-aligning roller bearing, but various bearing structures can be used as long as they are capable of exhibiting the self-aligning function. For example, the bearing body 14 shown in FIG. 1 is an outer ring rotating type bearing, but it may be an inner ring rotating type bearing instead. Furthermore, the movable raceway ring with the self-aligning function may be either the outer ring 22 or the inner ring 20.

[0044] In the above embodiment, the case has been described where the first sensor portion 40 of the rotation sensor 16 is fixed to the outer ring 22 and the second sensor portion 50 is fixed to the inner ring 20, but the arrangement of the rotation sensors may be reversed. Specifically, the bearing body 14 may be configured so that the first sensor portion 40 is fixed to the inner ring 20 and the second sensor portion 50 is fixed to the outer ring 22. In the example of Figures 1 and 2, the orientation of the brackets 42, 58 may be changed, and then the first sensor portion 40 may be assembled to the inner ring 20 and the second sensor portion 50 to the outer ring 22.

[0045] In the above embodiment, the magnetic encoder 44 is configured from two magnetic rubber pieces 45 and 46, but the configuration of the magnetic encoder is not limited to this. For example, the magnetic encoder may be configured from only one magnetic rubber piece, or may be configured from a gear-shaped silicon steel plate.

[0046] Although not specifically mentioned in the above embodiment, the rotation sensor 16 may be provided with a seal mechanism for preventing leakage of lubricating oil, if necessary. In this case, the seal mechanism may have various configurations, including [1] a lip-shaped contact rubber seal that maintains a tight seal even when the movable raceway moves due to self-alignment, and [2] a non-contact rubber seal or shield with a labyrinth structure for suppressing torque. [Explanation of symbols]

[0047] 10: Bearing device (bearing device with rotation sensor), 12: Rotating shaft, 14: Bearing body, 16: Rotation sensor, 20: Inner ring, 22: Outer ring (movable raceway), 24: Rolling element, 44: Magnetic encoder (magnetic generating part), 52: Magnetic sensor (magnetic detecting part), B: Reference position, C: Bearing center, T: Arc-shaped track

Claims

1. A bearing device with a rotation sensor, comprising: a bearing body for holding a rotating shaft; and a rotation sensor mounted on the bearing body for detecting a rotation state of the rotating shaft, The bearing body is a bearing having a self-aligning function in which a movable raceway, which is either an inner raceway or an outer raceway, moves along an arc-shaped track centered on the bearing center, The rotation sensor includes: a magnetic field generating unit fixed to one of the inner ring and the outer ring and generating magnetic field; a magnetic detection unit fixed to the other of the inner ring and the outer ring to detect magnetism; Equipped with A bearing device with a rotation sensor, wherein the magnetic generating unit and the magnetic detecting unit are arranged at a distance along the axial direction of the rotating shaft with the axes of the inner ring and the outer ring aligned, and the amount of positional deviation between their front positions in the radial direction of the rotating shaft that occurs as the movable race moves along the arc-shaped orbit is smaller than the amount of displacement of the movable race associated with the movement.

2. The rotation sensor includes: A substrate to which the magnetic detection unit is fixed on a front side thereof; A cable connected to the rear side of the substrate and extending along the axial direction of the bearing body.

2. The bearing device with a rotation sensor according to claim 1.

3. one of the magnetic field generating unit and the magnetic field detecting unit is disposed parallel to a radial direction of the rotation shaft, the other of the magnetic generation unit and the magnetic detection unit is disposed inclined with respect to a radial direction of the bearing body along a direction perpendicular to the arc-shaped track.

3. The bearing device with a rotation sensor according to claim 1 or 2.

4. The rotating shaft is an output shaft of an elevator hoisting machine. The bearing device with a rotation sensor according to any one of claims 1 to 3.

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