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

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

Background Art

[0002] Conventionally, 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 is known. As an example of the detection method of this rotation sensor, a magnetic generation part that is fixed to one of the inner ring and the outer ring and generates magnetism, and a magnetic detection part that is fixed to the other of the inner ring and the outer ring and detects magnetism are arranged apart from each other, and a magnetic rotation sensor that detects the rotation state of the rotating shaft based on the detection result of magnetism can be mentioned (see Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] <00000!7>For example, in large-scale mechanical equipment including an elevator hoist, a bearing body having a so-called automatic centering function (or automatic aligning function) may be used in order to cope with the deflection of the rotating shaft due to high load. When this automatic centering function is exerted, one of the inner ring and the outer ring (hereinafter, the movable raceway ring) moves along an arc-shaped raceway centered on the bearing center. That is, even though the rotating shaft is at the same angular position, the distance between the magnetic generation part and the magnetic detection part may change according to the position of the movable raceway ring. As a result, there arises a problem that the detection accuracy of the rotation state decreases.

[0005] <00!0030>The present invention has been made in view of these problems, and its objective 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 self-aligning function. [Means for solving the problem]

[0006] A bearing device with a rotation sensor according to a first aspect of the present invention comprises a bearing body that holds a rotating shaft, and a rotation sensor mounted on the bearing body for detecting the rotation state of the rotating shaft, wherein the bearing body is a bearing having an auto-aligning function in which a movable raceway, which is either an inner ring or an outer ring, moves along an arc-shaped trajectory centered on the bearing center, and the rotation sensor comprises a magnetic generating unit fixed to one of the inner ring and the outer ring that emits magnetism, and a magnetic detecting unit fixed to the other of the inner ring and the outer ring that detects magnetism, wherein the magnetic generating unit and the magnetic detecting unit are spaced apart along the radial direction of the rotating shaft with the axes of the inner ring and the outer ring 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 on which the magnetic detection unit is fixed to the front side, and a bias magnet provided on the back side of the substrate that emits bias magnetism.

[0008] In the bearing device with a rotation sensor according to the third aspect of the present invention, one of the magnetic field generating unit and the magnetic field detection unit is arranged parallel to the axial direction of the bearing body, and the other of the magnetic field generating unit and the magnetic field detection unit is arranged inclined with respect to the axial direction of the bearing body in a direction along the arc-shaped track.

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

[0010] According to the present invention, it is possible to suppress the decrease in detection accuracy caused by the combination of a magnetic rotation sensor and an automatic self-aligning function. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view of a bearing device with a rotation sensor according to one embodiment of the present invention. [Figure 2] This is a partially enlarged view of region A shown in Figure 1. [Figure 3] Figure 2 is a schematic diagram illustrating the effects of the arrangement of the rotation sensors. [Figure 4] This is a schematic diagram showing the arrangement of rotation sensors in another example. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below with reference to the attached drawings. To facilitate understanding of the description, the same reference numerals are used for identical components in each drawing whenever possible, and redundant explanations are omitted.

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

[0014] As shown in Figure 1, the bearing device 10 basically consists of a bearing body 14 that has an automatic self-aligning function and holds the rotating shaft 12, and a rotation sensor 16 mounted on the bearing body 14. This bearing device 10 is suitable for equipment where the rotating shaft 12 is prone to deflection or misalignment of the assembly position, specifically large machinery including elevator hoisting machines.

[0015] The bearing body 14 is a so-called double-row self-aligning roller bearing. Specifically, the bearing body 14 comprises an inner ring 20 that holds the rotating shaft 12, an outer ring 22 with a larger diameter than the inner ring 20, a plurality of rolling elements 24, two cages 26a and 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 provided in two rows in the axial direction of the bearing body 14. Half (N) of the 2N rolling elements 24 are held by one cage 26a in a state of being arranged at substantially equal intervals along the circumferential direction of the bearing body 14. The remaining half (N) of the 2N rolling elements 24 are held by the other cage 26b in a state of being arranged at substantially equal intervals along the circumferential direction of the bearing body 14.

[0017] Each rolling element 24 has a substantially barrel shape and is provided so as to be rotatable between the inner ring 20 and the outer ring 22. Specifically, the outer peripheral surface of the rolling element 24 performs rolling contact between 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 a bearing of the outer ring rotation type, the inner ring 20 remains fixed to the housing 28 or the like, and the outer ring 22 rotates integrally with the rotating shaft 12.

[0018] Here, the outer ring 22 functions as a movable raceway ring with an automatic centering 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 track along the raceway surface 23 with respect to the inner ring 20. The reference position B indicates the neutral point of the movable range of the outer ring 22. That is, when the outer ring 22 is at the reference position B, the axes of both the inner ring 20 and the outer ring 22 completely coincide.

[0019] The oil seal 30 is a substantially annular member that prevents the leakage of lubricating oil for reducing the frictional force when the rolling element 24 moves. The oil seal 30 is provided so as to span the inner ring 20 and the outer ring 22 axially outside the position of the cage 26a. On the other hand, a rotation sensor 16 is attached at the corresponding position of the cage 26b (that is, the gap between the inner ring 20 and the outer ring 22) instead of the oil seal.

[0020] As shown in FIG. 2, the rotation sensor 16 includes 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 captures changes in magnetism associated with relative movement between the inner ring 20 and the outer ring 22, and detects the rotation state (e.g., angular position, rotational speed, rotation direction, etc.) of the rotation axis 12.

[0021] The first sensor unit 40 is composed of a magnetic encoder 44 provided integrally with the seal base material 42. By annularly attaching the seal base material 42 to the raceway surface 23 of the outer ring 22, the first sensor unit 40 is fixed to the outer ring 22.

[0022] The magnetic encoder 44 functions as a "magnetic generation unit" that emits magnetism correlated with the angular position of the rotation axis 12. The magnetic encoder 44 is formed by laminating two magnetized rubber sheets 45 and 46 that are each multi-pole magnetized. By slightly shifting the magnetization pitch of the magnetized rubber sheets 45 and 46, the absolute angular position of the rotation axis 12 can be specified.

[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 the magnetism by the magnetic encoder 44. The magnetic sensor 52 is, for example, an integrated circuit incorporating a Hall element that detects a magnetic pattern indicating the time change of magnetism. As understood from FIG. 2, the magnetic encoder 44 and the magnetic sensor 52 are arranged spaced apart along the radial direction of the rotation axis 12 (or the bearing body 14). Note that "along the radial direction" includes not only the case where it coincides with the radial direction but also the case where it is inclined within a predetermined allowable range (generally within ±20 degrees) with respect to the radial direction.

[0025] The substrate 54 is an electronic circuit board that processes the electrical signals output from the magnetic sensor 52. The front side of the substrate 54 is provided with the magnetic sensor 52 and other electronic components (not shown). The back side of the substrate 54 is provided with a connector 55 for connecting a cable 58 and a bias magnet 56 that emits a magnetic bias. For example, the bias magnet 56 is positioned so as to at least partially overlap the magnetic sensor 52 in a plan view.

[0026] The cable 58 is connected to the connector 55 on the circuit board 54 and is routed to extend along the axial direction of the bearing body 14. This supplies drive power to the circuit board 54 through the cable 58, and the circuit board 54 outputs an electrical signal through the cable 58 indicating the rotational state of the rotating shaft 12 detected by the magnetic sensor 52.

[0027] The substrate 54 and cable 58 are held by a holder 60 which is roughly rectangular in shape. The holder 60 is mounted inside an annular bracket 62 which has 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 explained with reference to Figures 1 to 4.

[0029] As shown in Figures 1 and 2, as the housing 28 rotates, the first sensor part 40 of the rotation sensor 16 rotates together with the outer ring 22. On the other hand, the second sensor part 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 the change in the relative positional relationship between the first sensor part 40 and the second sensor part 50, and detects the rotational state of the rotation shaft 12. Meanwhile, when the rotation shaft 12 flexes during this rotational motion, causing the bearing body 14 to perform its self-aligning function, the outer ring 22 moves from the reference position B along the arc-shaped trajectory T.

[0030] Figure 3 is a schematic diagram showing the effects of the arrangement of the rotation sensor 16 in Figure 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 Figure 2.

[0031] The trajectory T is an arc-shaped trajectory in 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 the 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 trajectory surface 23. D is the distance between the magnetic encoder 44 at point P and the magnetic sensor 52.

[0032] Geometric analysis reveals that the distance between points PQ is 2R·sin(Δθ / 2), and the radial displacement between points PQ is R·(1-cosΔθ). Here, since the magnetic encoder 44 and magnetic sensor 52 are spaced apart radially, the change in distance D due to the movement of the outer ring 22 becomes smaller. As a result, even when the outer ring 22 moves along an 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] Figure 4 is a schematic diagram showing the arrangement of the rotation sensor 16 in another example. Here, the magnetic sensor 52 is positioned so as to be tilted outward by φ with respect to the axial direction. The tilt angle φ is set, for example, so that the distance (D) between points PQ is approximately equal. This configuration further reduces the amount of change in distance D in a particular section of the trajectory T.

[0034] Generally speaking, the outer ring 22 is considered to move with approximately the same frequency in the forward or backward direction in the axial direction, with reference position B as its center of movement. In this case, adopting the arrangement shown in Figure 3 is effective. However, depending on the assembly state and usage conditions of the bearing device 10, the center of movement of the outer ring 22 may shift from reference position B. In this case, adopting the arrangement shown in Figure 4 is effective.

[0035] In Figure 4, the magnetic sensor 52 is positioned so as to be tilted outward by φ with respect to the axial direction, but the opposite relationship is also possible. Specifically, the magnetic encoder 44 may be positioned so as to be tilted outward by φ with respect to the axial direction. This configuration also further reduces the amount of change in distance D in a specific section of the trajectory T.

[0036] Alternatively, both the magnetic encoder 44 and the magnetic sensor 52 may be positioned at an angle 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 angle of inclination) or non-parallel to the magnetic sensor 52 (i.e., at different angles of inclination). In particular, when they are parallel, the change in distance D at a particular point Q on the trajectory T becomes even smaller.

[0037] [Summary of Embodiments] As described above, the bearing device 10 comprises a bearing body 14 that holds the rotating shaft 12, and a rotation sensor 16 mounted on the bearing body 14 that detects the rotation state of the rotating shaft 12. The bearing body 14 consists of a bearing having an auto-aligning function in which a movable raceway (here, the outer ring 22), which is either the inner ring 20 or the outer ring 22, moves along an arc-shaped raceway T centered on the bearing center C. The rotation sensor 16 comprises a magnetic generation unit (here, a magnetic encoder 44) fixed to one of the inner ring 20 or the outer ring 22 that emits magnetism, and a magnetic detection unit (here, a magnetic sensor 52) fixed to the other of the inner ring 20 or the outer ring 22 that detects magnetism. The magnetic encoder 44 and the magnetic sensor 52 are spaced apart along the radial direction of the bearing body 14 when the axes of the inner ring 20 and the outer ring 22 are aligned (i.e., at the reference position B).

[0038] In this way, the magnetic encoder 44 and magnetic sensor 52 are spaced apart in the radial direction, that is, in a direction approximately perpendicular to the arc-shaped trajectory T, so the amount of change in distance D due to the movement of the outer ring 22 is reduced. As a result, even when the outer ring 22 moves along the trajectory T, the relationship between the magnetic detection result by the rotation sensor 16 and the angular position is more easily maintained. In other words, the decrease in detection accuracy caused by the combination of a magnetic rotation sensor and an automatic centering function can be suppressed.

[0039] Furthermore, the rotation sensor 16 may further include a substrate 54 on which the magnetic sensor 52 is provided on the front side, and a bias magnet 56 provided on the back side of the substrate 54 that emits bias magnetism. This makes it easier to detect changes in magnetism by adding bias magnetism, even when 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 (the magnetic encoder 44) may be arranged parallel to the axial direction of the rotation axis 12, while the other (the magnetic sensor 52) may be arranged at an inclination with respect to the axial direction of the rotation axis 12, in a direction along the arc-shaped trajectory T. This makes it possible to reduce the amount of change in distance D in a specific section on the trajectory T.

[0041] Furthermore, the rotating shaft 12 may also be the output shaft of an elevator hoisting machine. During the operation of the elevator hoisting machine, the radial load makes the rotating shaft 12 more prone to deflection, thus increasing the frequency with which the self-aligning function is activated. Consequently, the effect of suppressing the decrease in detection accuracy becomes more pronounced.

[0042] [Differentiation] It should be noted that the present invention is not limited to the embodiments described above, and can be freely modified without departing from the spirit of the invention. Alternatively, each component may be combined in any way that does not create a technical inconsistency.

[0043] In the embodiment described above, the case in which the bearing body 14 is a double-row self-aligning roller bearing was explained, but various bearing structures can be used as long as the self-aligning function can be performed. For example, the bearing body 14 shown in Figure 1 is an outer ring rotating type bearing, but an inner ring rotating type bearing may be used instead. Also, the movable raceway ring for the self-aligning function may be either the outer ring 22 or the inner ring 20.

[0044] In the embodiment described above, the case in which the first sensor part 40 of the rotation sensor 16 is fixed to the outer ring 22 and the second sensor part 50 is fixed to the inner ring 20 was explained, but the arrangement of the rotation sensor may be reversed. Specifically, the bearing body 14 may be configured to fix the first sensor part 40 to the inner ring 20 and the second sensor part 50 to the outer ring 22.

[0045] In the embodiment described above, the case in which the magnetic encoder 44 is composed of two magnetic rubbers 45 and 46 was explained, but the configuration of the magnetic encoder is not limited to this. For example, the magnetic encoder may be composed of only one magnetic rubber, or it may be composed of a gear-shaped silicon steel plate.

[0046] Although not specifically mentioned in the embodiments described above, the rotation sensor 16 may be provided with a sealing mechanism to prevent leakage of lubricating oil, if necessary. In this case, the sealing mechanism can employ various configurations, including [1] a lip-shaped contact rubber seal that maintains airtightness even when the movable raceway wheel moves due to self-alignment, and [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 generation unit), 52...Magnetic sensor (magnetic detection unit), B...Reference position, C...Bearing center, T...Arch-shaped raceway

Claims

1. A bearing device with a rotation sensor, comprising a bearing body that holds a rotating shaft, and a rotation sensor mounted on the bearing body that detects the rotation state of the rotating shaft, The bearing body is a self-aligning bearing in which a movable raceway, which is either an inner ring or an outer ring, moves along an arc-shaped track centered on the bearing center. The aforementioned rotation sensor is A magnetic generating unit fixed to one of the inner ring and the outer ring and emitting magnetism, A magnetic detection unit is fixed to the other of the inner and outer rings to detect magnetism, Equipped with, When the position of the movable raceway when the axes of the inner and outer rings coincide is defined as the first position, and the position of the movable raceway when it reaches the endpoint of the arc-shaped track is defined as the second position, The magnetic field generating unit and the magnetic field detecting unit are spaced apart along the radial direction of the rotation axis when the movable track wheel is in the first position. A bearing device with a rotation sensor, characterized in that, when the movable raceway is in the first position, one of the magnetic generating unit and the magnetic detecting unit is arranged parallel to the axial direction of the rotation shaft, and the other of the magnetic generating unit and the magnetic detecting unit is arranged inclined with respect to the axial direction of the rotation shaft so as to be parallel to the tangential direction of the arc-shaped raceway at a predetermined intermediate position between the first position and the second position.

2. The aforementioned rotation sensor is The magnetic detection unit is fixed to the front side of the substrate, A bias magnet provided on the back side of the substrate and emitting bias magnetism, The bearing device with a rotation sensor according to claim 1, further comprising the features described above.

3. The bearing device with a rotation sensor according to claim 1 or 2, characterized in that the rotating shaft is the output shaft of an elevator hoisting machine.

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