Bearing device with rotation sensor

Abstract

To provide a bearing device with a rotation sensor that can suppress a decrease in detection precision due to a combination of the magnetic rotation sensor and an automatic self-aligning function.SOLUTION: A bearing body 14 consists of a bearing with a self-aligning function such that the outer ring 22 moves along an arcuate track T having its center in the center C of the bearing. A rotation sensor 16 comprises a magnetic encoder 44 which is fixed to one of the inner ring 20 and outer ring 22, and generates magnetism, and a magnetic sensor 52 which is fixed to the other of the inner ring 20 and outer ring 22, and detects the magnetism. The magnetic encoder 44 and magnetic sensor 52 are arranged apart along a radial direction of a rotary shaft 12 with the axes of the inner ring 20 and outer ring 22 aligned with each other, and also so provided that the quantity of variation in distance in the radial direction of the rotary shaft 12 which is caused as the outer ring 22 moves along the arcuate track T is smaller than the quantity of variation of the outer ring 22 accompanying the movement.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 that detects 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 magnetism, and a magnetic detecting unit that is fixed to the other of the inner and outer rings and detects magnetism, are disposed separately, and the rotation state of the rotating shaft is detected based on the magnetic detection results (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-286266 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-127688 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, large machinery and equipment, including elevator hoists, often use bearing bodies with a so-called self-aligning function to accommodate deflection of the rotating shaft due to high loads. When this self-aligning function is activated, one of the inner and outer raceways (hereinafter referred to as the movable raceway) 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 distance between the magnetic generator and the magnetic detector may change depending on the position of the movable raceway. This results in a problem of reduced accuracy in detecting the rotation state.

[0005] The present invention has been made in consideration of these problems, and its purpose is to provide a bearing device with a rotation sensor that can suppress the decrease in detection accuracy that results from 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 that is mounted on the bearing body and detects the rotational state of the rotating shaft, wherein the bearing body is a bearing with a self-aligning function in which a movable raceway, which is one of the inner and outer rings, moves along an arc-shaped orbit centered on the bearing center, and the rotation sensor comprises a magnetic generating unit that is fixed to one of the inner and outer rings and generates magnetism, and a magnetic detecting unit that is fixed to the other of the inner and outer rings and detects magnetism, and the magnetic generating unit and the magnetic detecting unit are arranged at a distance along the radial direction of the rotating shaft with the axes of the inner and outer rings aligned.

[0007] In a bearing device with a rotation sensor according to a second aspect of the present invention, the rotation sensor further comprises a substrate to which the magnetic detection unit is fixed on the front side, and a bias magnet provided on the back side of the substrate and emitting bias magnetic field.

[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 axial direction of the bearing body, and the other of the magnetic generating unit and the magnetic detecting unit is arranged at an angle in a direction along the arc-shaped orbit with respect to the axial direction of the bearing body.

[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. [Effects 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 explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view of a bearing device with a rotation sensor according to an embodiment of the present invention. [Figure 2] FIG. 2 is a partial enlarged view of an area A shown in FIG. [Figure 3] 3 is a schematic diagram showing the effects of the arrangement of the rotation sensors in FIG. 2.

[0023] FIG. [Figure 4] FIG. 10 is a schematic diagram showing the arrangement of rotation sensors in another example. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

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

[0014] As shown in Figure 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 that is mounted on bearing body 14. This bearing device 10 is suitable for devices where bending of the rotating shaft 12 or misalignment 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 elements) are held by one of the cages 26a and arranged at approximately equal intervals along the circumferential direction of the bearing body 14. The other half of the 2N rolling elements 24 (N elements) are held by the other cage 26b and 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 so as 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 the housing 28 or the like.

[0018] Here, the outer ring 22 functions as a movable bearing ring with a self-aligning function. In this case, a spherical 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 path along the raceway surface 23 relative to the inner ring 20. Note that a reference position B indicates the 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, spanning 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 on 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. The 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 (for example, the angular position, rotation speed, rotation direction, etc.).

[0021] The first sensor unit 40 is composed of a magnetic encoder 44 that is provided integrally with the seal base material 42. The first sensor unit 40 is fixed to the outer ring 22 by attaching the seal base material 42 in an annular shape to the raceway surface 23 of the outer ring 22.

[0022] The magnetic encoder 44 functions as a "magnetic field generating unit" that generates magnetism that correlates with the angular position of the rotating shaft 12. The magnetic encoder 44 is made up of two laminated magnetic rubber pieces 45 and 46, each magnetized with multiple poles. By slightly shifting the magnetization pitch of the magnetic rubber pieces 45 and 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 bias magnet 56 , a cable 58 , a holder 60 , and a bracket 62 .

[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 changes in magnetism over time. As can be seen from FIG. 2, the magnetic encoder 44 and the magnetic sensor 52 are disposed apart from each other along the radial direction of the rotating shaft 12 (or the bearing body 14). Note that "along the radial direction" not only refers to a case where the magnetic sensor 52 is aligned with the radial direction, but also includes a case where the magnetic sensor 52 is inclined relative to the radial direction within a predetermined tolerance range (generally within ±20 degrees).

[0025] The substrate 54 is an electronic circuit board that processes the electrical signal output from the magnetic sensor 52. The magnetic sensor 52 and electronic components (not shown) are provided on the front side of the substrate 54. A connector 55 for connecting a cable 58 and a bias magnet 56 that emits a magnetic bias are provided on the back side of the substrate 54. For example, the bias magnet 56 is disposed in a position that at least partially overlaps with the magnetic sensor 52 in a plan view.

[0026] The cable 58 is connected to the connector 55 of the circuit board 54 and is wired to extend along the axial direction of the bearing body 14. As a result, driving power is supplied to the circuit board 54 through the cable 58, and the circuit board 54 outputs, through the cable 58, an electrical signal that indicates the rotation state of the rotating shaft 12 detected by the magnetic sensor 52.

[0027] The substrate 54 and the cable 58 are held by a roughly rectangular parallelepiped holder 60. The holder 60 is attached to the inside of an annular bracket 62 having a roughly C-shaped cross section. As a result, the second sensor unit 50 is fixed to the outer edge of the raceway surface 21 of the inner ring 20 via the bracket 62.

[0028] [Operation of bearing device 10] The bearing device 10 in this embodiment is configured as described above. Next, the operation of this 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 movement, the outer ring 22 will move from a reference position B along an arc-shaped trajectory T.

[0030] Fig. 3 is a schematic diagram showing the effects 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 diagram 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 has moved by an angle Δθ. R is the radius of curvature of the orbital surface 23. D is the distance between the magnetic encoder 44 located at point P and the magnetic sensor 52.

[0032] From geometric considerations, the distance between points P and Q is calculated to be 2R sin(Δθ / 2), and the radial displacement between points P and Q is calculated to be R (1-cosΔθ). Here, because the magnetic encoder 44 and the magnetic sensor 52 are arranged at a distance from each other in the radial direction, the amount of change in distance D caused by 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 more 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 that it is tilted outward by an angle φ relative to the axial direction. The tilt angle φ is set, for example, so that the distance (D) between points P and Q is approximately equal. By configuring in this way, the amount of change in the distance D in a specific section on the trajectory 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 arrangement 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 arrangement shown in FIG. 4.

[0035] 4, the magnetic sensor 52 is disposed so as to be inclined outward by φ with respect to the axial 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 axial direction. This configuration also further reduces the amount of change in the distance D 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 axial direction. In this case, the magnetic encoder 44 may be parallel to the magnetic sensor 52 (i.e., at the same inclination angle) or non-parallel to the magnetic sensor 52 (i.e., at a different inclination angle). In particular, when the magnetic encoder 44 and the magnetic sensor 52 are parallel, the amount of change in the distance D 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 a bearing body 14 that holds the rotating shaft 12, and a rotation sensor 16 that is mounted on the bearing body 14 and detects the rotational state of the rotating shaft 12. The bearing body 14 is a bearing with 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 field generating unit (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 field detecting unit (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 in the radial direction of the bearing body 14 with the axes of the inner raceway 20 and the outer raceway 22 aligned (i.e., at reference position B).

[0038] In this way, the magnetic encoder 44 and the magnetic sensor 52 are disposed apart in the radial direction, i.e., in a direction substantially perpendicular to the arc-shaped orbit T, so that the amount of change in the distance D caused by 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 bias magnet 56 that is provided on the back side of the substrate 54 and emits bias magnetism. This makes it easier to detect changes in magnetism due to the addition of bias magnetism, even if the distance D between the magnetic encoder 44 and the magnetic sensor 52 increases as the outer ring 22 moves.

[0040] Furthermore, one of the magnetic encoder 44 and the magnetic sensor 52 (magnetic encoder 44) may be arranged parallel to the axial direction of the rotating shaft 12, while the other (magnetic sensor 52) may be arranged at an angle in a direction along the arc-shaped trajectory T with respect to the axial direction of the rotating shaft 12. This makes it possible to reduce the amount of change in the distance D in a specific section on the trajectory 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, which increases the frequency with which the self-aligning function is 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 of the present invention. Alternatively, the respective configurations may be arbitrarily combined within the scope of the present invention 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 providing self-aligning functionality. For example, while the bearing body 14 shown in FIG. 1 is an outer-ring rotating type bearing, it may instead be an inner-ring rotating type bearing. Furthermore, the movable bearing ring with self-aligning functionality may be either the outer ring 22 or the inner ring 20.

[0044] In the above embodiment, 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.

[0045] In the above embodiment, the magnetic encoder 44 is configured from two magnetic rubber pieces 45 and 46. However, the configuration of the magnetic encoder is not limited to this. For example, the magnetic encoder may be configured from only one piece of magnetic rubber, 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 to prevent 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 sealing even when the movable bearing ring moves due to self-alignment, or [2] a non-contact rubber seal or shield with a labyrinth structure to suppress 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 rotation sensor mounted bearing device, characterized in that the magnetic generating unit and the magnetic detecting unit are arranged at a distance from each other along the radial direction of the rotating shaft with the axes of the inner ring and the outer ring aligned, and are arranged so that the change in distance in the radial direction of the rotating shaft that occurs as the movable raceway moves along the arc-shaped orbit is smaller than the displacement of the movable raceway that occurs as the movable raceway moves along the arc-shaped orbit.

2. 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 one of the magnetic generation unit and the magnetic detection unit is disposed parallel to the axial direction of the rotating shaft with the axes of the inner ring and the outer ring coinciding with each other; A bearing device with a rotation sensor, characterized in that the other of the magnetic generating unit and the magnetic detecting unit is arranged at an angle in a direction along the arc-shaped orbit with respect to the axial direction of the rotating shaft, with the axes of the inner ring and the outer ring aligned.

3. The rotation sensor includes: A substrate to which the magnetic detection unit is fixed on a front side thereof; a bias magnet provided on the rear side of the substrate and generating a bias magnetism; 3. The bearing device with a rotation sensor according to claim 1, further comprising:

4. 3. The bearing device with a rotation sensor according to claim 1, wherein the rotating shaft is an output shaft of an elevator hoist.

Images