JP2010190248A - Roller bearing with rotation sensor - Google Patents

Abstract

A rolling bearing with a rotation sensor that is inexpensive and easy to manufacture is provided.
A rotation sensor for detecting the rotation of an inner ring, which is a rotating wheel, is attached to the deep groove ball bearing. The rotation sensor includes a detected portion including a magnetic tone ring 10 attached to the inner ring 1 so as to be rotatable integrally with the inner ring 1, and a detection unit 20 attached to the outer ring 2 which is a fixed ring. Has been. The detection unit 20 includes a magnetic back yoke 23, a magnetic sensor 21, and a bias magnet 22 disposed between the back yoke 23 and the magnetic sensor 21. The detection unit 20 and the detected unit are arranged to face each other in the radial direction with a gap therebetween, and a magnetic circuit is formed by the detection unit 20 and the detected unit, and the detected unit accompanying the rotation of the inner ring 1 Is detected by the detection unit 20.
[Selection] Figure 1

Description

  The present invention relates to a rolling bearing including a rotation sensor that detects rotation of a race.

  Patent Document 1 discloses a sensor-equipped bearing unit that includes a pulsar ring provided on a rotating wheel and a sensor device provided on a fixed wheel. The pulsar ring, which is the detected part, has two magnetic generation layers in which a plurality of magnetic generation units are formed at an equal pitch in the circumferential direction, and the two magnetic generation layers are arranged in the radial direction so that different magnetic poles face each other. It is a multipole magnet that is superposed.

  In addition, a sensor device as a detection unit includes a magnetic sensor opposed to the pulsar ring, a magnetism generating member (permanent magnet) facing the magnetic sensor via the pulsar ring and generating magnetism, and the magnetism generating member and the pulsar ring. A magnetic flux collecting member (yoke) that focuses the magnetic flux density from the magnetic field and guides it to the magnetic sensor. Such a bearing unit with a sensor is less likely to have a reduced resolution even if the diameter is reduced.

JP 2004-170344 A

  However, the above multipole magnet has a problem that it is expensive. Further, in order to magnetize the multipolar magnet in two layers, the width and thickness of the annular magnet are required to some extent, so that there has been a limit to reducing the diameter of the sensor. Furthermore, since the multipolar magnet is arranged inside the substantially U-shaped magnetic flux collecting member, there are problems that it is difficult to manage the gap between the multipolar magnet and the magnetic flux collecting member, and that the structure is complicated. It was.

  Accordingly, an object of the present invention is to solve the above-described problems of the prior art and to provide a rolling bearing with a rotation sensor that is inexpensive and easy to manufacture.

  In order to solve the above problems, the present invention has the following configuration. That is, the rolling bearing with a rotation sensor according to the present invention includes a rotatable rotating wheel, a fixed wheel that rotatably supports the rotating wheel, a raceway surface that the rotating wheel has, and a raceway surface that the fixed wheel has. In a rolling bearing with a rotation sensor, comprising: a plurality of rolling elements arranged so as to be freely rotatable; and a rotation sensor that detects rotation of the rotating wheel, the rotation sensor is configured to be rotatable integrally with the rotating wheel. A detected portion made of an annular member made of a magnetic material attached to a rotating wheel, and at least one detecting portion attached to the fixed wheel and arranged to face the detected portion in a radial direction with a gap therebetween And the detection unit includes a back yoke made of a magnetic material, a magnetic sensor, and a bias magnet disposed between the back yoke and the magnetic sensor. With the detector Magnetic circuit is formed, the rotation of the detected part caused by the rotation of the rotary wheel, characterized in that is adapted to be detected by the detection unit.

  In this rolling bearing with a rotation sensor, the back yoke is bent and has a substantially L-shaped cross section, and one end thereof is opposed to the annular member in the radial direction through a gap, and the vicinity of the other end And the annular member has an annular portion whose entire circumferential surface can be opposed to the one end portion of the back yoke in the radial direction via a gap, and the annular portion extends from the annular portion to the bearing central shaft. A plurality of convex portions projecting in a direction along the circumferential direction are provided at equal intervals in the circumferential direction, and the convex portions can be opposed to a magnetic detection surface of the magnetic sensor in a radial direction through a gap. preferable.

  The magnetic sensor is preferably a differential Hall IC.

  The rolling bearing with a rotation sensor of the present invention is inexpensive and easy to manufacture.

It is a longitudinal cross-sectional view which shows the structure of one Embodiment of the rolling bearing with a rotation sensor which concerns on this invention. It is a perspective view of a tone ring. It is a perspective view of a back yoke. It is the front view and side view explaining the mechanism which detects rotation of a tone ring by a detection part. It is the front view and side view explaining the mechanism which detects rotation of a tone ring by a detection part. It is a perspective view which shows the modification of a back yoke. It is a figure explaining operation | movement of a differential Hall IC.

  Embodiments of a rolling bearing with a rotation sensor according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a structure of an embodiment of a rolling bearing with a rotation sensor according to the present invention, and FIG. 2 is a perspective view of a tone ring incorporated in the rolling bearing with a rotation sensor of FIG. FIG. 3 is a perspective view of the back yoke incorporated in the rolling bearing with a rotation sensor of FIG.

  The deep groove ball bearing shown in FIG. 1 is rotatable between an inner ring 1 having a raceway surface 1a on an outer peripheral surface, an outer ring 2 having a raceway surface 2a facing the raceway surface 1a on an inner peripheral surface, and both raceway surfaces 1a and 2a. A plurality of rolling elements (balls) 3 disposed on the inner ring 1, a retainer 4 that holds the rolling elements 3 between the inner ring 1 and the outer ring 2, and a sealing device 5 that covers an opening of a gap between the inner ring 1 and the outer ring 2 ( (For example, a steel shield or rubber seal), and a bearing inner space formed between the outer peripheral surface of the inner ring 1 and the inner peripheral surface of the outer ring 2 is provided with a lubricant (for example, lubricating oil, grease) (not shown). Is enclosed.

  In this deep groove ball bearing, for example, the inner ring 1 is fitted on a rotating shaft (not shown) to be a rotatable rotating ring, and the outer ring 2 is fixed to a housing (not shown), for example, to rotate the rotating wheel. The fixed ring is supported as possible. The sealing device 5 is provided only at one end in the bearing central axis direction of the deep groove ball bearing, and a rotation sensor that detects the rotation of the inner ring 1 that is a rotating wheel is attached to the other end. ing. However, it goes without saying that the inner ring 1 may be a fixed ring and the outer ring 2 may be a rotating wheel. Further, the cage 4 and the sealing device 5 may not be provided.

Next, the configuration of the rotation sensor will be described. The rotation sensor includes a detected portion made of a tone ring 10 that is an annular member made of a magnetic material, and a detecting portion 20 made of a magnetic sensor 21, a bias magnet (single pole) 22, and a back yoke 23 made of a magnetic material. It is configured.
Note that the type of the magnetic material constituting the tone ring 10 and the back yoke 23 is not particularly limited, but SPCC or SUS430 is preferable. For example, SPCC is inexpensive, and SUS430 is excellent in corrosion resistance. Therefore, an optimal material may be selected according to important points such as cost and corrosion resistance. Moreover, although the manufacturing method of the tone ring 10 and the back yoke 23 is not particularly limited, the punching method and the pressing method are preferable because they can be manufactured at low cost.

  The tone ring 10 includes an annular portion 11 having a circumferential surface and a plurality of convex portions 12 projecting from the annular portion 11 in a direction along the bearing central axis (that is, in the bearing width direction). The annular part 11 is provided at equal intervals in the circumferential direction. That is, the circumferential surface is formed over the entire circumference on one side of the bearing ring direction of the tone ring 10, but the circumferential surface is not formed over the entire circumference on the other side. The circumferential surface and the space are alternately arranged in the circumferential direction (hereinafter, the space may be referred to as a recess 13).

Such a tone ring 10 is attached to the inner ring 1 so as to be rotatable integrally with the inner ring 1 which is a rotating wheel, with the annular part 11 facing the center side in the bearing width direction and the convex part 12 facing the outer side in the bearing width direction. It has been. The attachment method is not particularly limited, and examples thereof include attachment by press-fitting or caulking.
On the other hand, the back yoke 23 is a member formed by bending a rectangular plate-like member into a substantially L-shaped cross section as shown in FIG. The back yoke 23 is composed of a long flat plate portion 25 and a short flat plate portion 26. Of the two flat surfaces of the long flat plate portion 25, on the plane in the direction in which the short flat plate portion 26 is bent, A bias magnet 22 is fixed, and a magnetic sensor 21 is further fixed thereon. In other words, the bias magnet 22 is interposed between the back yoke 23 and the magnetic sensor 21 to constitute the detection unit 20.

  Such a detection unit 20 is attached to the outer ring 2 which is a fixed ring. At that time, the short flat plate portion 26 of the back yoke 23 is directed to the center side in the bearing width direction, the long flat plate portion 25 is directed to the outer side in the bearing width direction, and the front end surface 26a of the short flat plate portion 26 is made to have a diameter. The detection unit 20 is attached inward in the direction. In addition, the detection unit 20 is attached in a state where the back yoke 23, the magnetic sensor 21, the bias magnet 22, and the cable 28 for taking out a signal are enclosed in a resin case called a sensor housing 29. In addition, when a gap remains in the sensor housing 29 after the detection unit 20 is enclosed in the sensor housing 29, the detection unit 20 should be exposed by filling the gap with a resin such as silicone resin or hot melt molding. It is preferable to mold so that parts other than the part are not exposed to the outside.

  The detected part composed of the tone ring 10 attached to the inner ring 1 and the detecting part 20 attached to the outer ring 2 are arranged to face each other in the radial direction with a gap between them, and the detecting part 20 and the detected part A magnetic circuit is formed. This point will be described in detail below. First, the circumferential surface of the annular portion 11 of the tone ring 10 (that is, the portion of the tone ring 10 on the center side in the bearing width direction) and the front end surface 26a of the short flat plate portion 26 of the back yoke 23 are interposed via a gap. Opposing in the radial direction. As for the annular portion 11 of the tone ring 10, since the circumferential surface is formed over the entire circumference, even if the tone ring 10 rotates with the rotation of the inner ring 1, the both surfaces always face each other.

  In addition, a portion of the tone ring 10 on the outer side in the bearing width direction and the magnetic detection surface 21a of the magnetic sensor 21 are opposed to each other in the radial direction through a gap. As for the portion of the tone ring 10 on the outer side in the bearing width direction, the circumferential surface is formed only on a part of the entire circumference, and the circumferential surface by the convex portion 12 and the concave portion 13 are alternately arranged in the circumferential direction. Therefore, when the tone ring 10 rotates with the rotation of the inner ring 1, the circumferential surface by the convex portion 12 and the concave portion 13 appear alternately in front of the magnetic detection surface 21 a of the magnetic sensor 21. When the circumferential surface of the convex portion 12 is located in front of the magnetic detection surface 21a of the magnetic sensor 21, these both surfaces are opposed to each other in the radial direction through a gap.

  Since the configuration of the magnetic circuit is different between the case where the circumferential surface of the convex portion 12 is positioned in front of the magnetic detection surface 21a of the magnetic sensor 21 and the case where the concave portion 13 is positioned, the magnetic detection surface 21a of the magnetic sensor 21 is The amount of magnetic flux passing through is different. Therefore, based on this change in the amount of magnetic flux, the rotation of the detected part can be detected by the detecting part 20, and the rotational speed and rotational speed of the inner ring 1 can also be measured. This point will be described with reference to FIGS.

  4 and 5 show the flow of main magnetic flux. The arrow by the broken line is the flow of magnetic flux. 4 is a diagram in the case where the circumferential surface of the convex portion 12 is positioned in front of the magnetic detection surface 21a of the magnetic sensor 21, and FIG. 5 is a diagram in which the concave portion 13 is positioned in front of the magnetic detection surface 21a of the magnetic sensor 21. FIG. 4 and 5 are views of the detected portion and the detection portion 20 as seen from the front direction of the bearing, and (b) is a view as seen from the side surface direction of the bearing.

  In the case of FIG. 4, the magnetic flux flows from the bias magnet 22 to the short flat plate portion 26 via the long flat plate portion 25 of the back yoke 23, and from the front end surface 26 a of the short flat plate portion 26 to the tone ring 10. It flows to the annular part 11. Then, it flows from the tip of the convex portion 12 to the magnetic sensor 21 via the convex portion 12 of the tone ring 10. On the other hand, in the case of FIG. 5, since there is no convex portion 12 in front of the magnetic detection surface 21 a of the magnetic sensor 21, it flows from the front end surface 26 a of the short flat plate portion 26 to the magnetic sensor 21 via the tone ring 10. The magnetic flux flowing from the vicinity of the central portion of the short flat plate portion 26 to the magnetic sensor 21 is larger than the magnetic flux. Therefore, the amount of magnetic flux passing through the magnetic detection surface 21a of the magnetic sensor 21 increases when the circumferential surface of the convex portion 12 is positioned in front of the magnetic detection surface 21a of the magnetic sensor 21. 4 and 5, the direction in which the magnetic flux flows is clockwise, but it may be counterclockwise, that is, the direction of the magnetic pole of the bias magnet may be reversed. Regardless of the direction in which the magnetic flux flows, the detection accuracy of rotation is the same.

As described above, the amount of magnetic flux passing through the magnetic detection surface 21a of the magnetic sensor 21 varies depending on the rotational position of the tone ring 10, and a square wave is output from the magnetic sensor 21 as an output signal. Therefore, the rotational speed of the inner ring 1 can be accurately measured using this output signal.
Such a rolling bearing with a rotation sensor does not require an expensive multi-pole magnet or the like for the rotation sensor, so that it is inexpensive and easy to manufacture. In addition, since the accuracy of the rotation sensor such as the pitch accuracy is caused by the machining accuracy of the tone ring 10, it is easy to make the accuracy higher than that of the rotation sensor using a multipolar magnet.

  Furthermore, since the tone ring 10 and the back yoke 23 can be manufactured by a punching method or a pressing method, the manufacturing cost is low compared to the case of manufacturing a multipolar magnet. Further, since the rotation sensor 21 has a structure in which the tone ring 10 and the detection unit 20 (the back yoke 23 and the magnetic sensor 21) are opposed to each other, the management of the gap between the two is easy and the structure is simple, and therefore the manufacturing is performed. Is easy. Further, the rotation sensor can be made smaller than a conventional rolling bearing with a rotation sensor using a multipolar magnet. Therefore, this rolling sensor-equipped rolling bearing can be suitably used as a component for industrial equipment or home appliances.

  In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment. For example, in the present embodiment, the front end surface 26a of the short flat plate portion 26 of the back yoke 23 is planar as shown in FIG. 3, but may be curved as shown in FIG. As the curved surface, an arc surface is preferable, and an arc surface having a radius of curvature slightly larger than the radius of the circumferential surface of the annular portion 11 of the tone ring 10 is more preferable. Then, the magnetoresistance of this part can be reduced.

  In addition, the dimensions of the members such as the tone ring 10 and the back yoke 23 can be appropriately designed according to the dimensions of the rolling bearing and the strength of the magnetic force. For example, in the present embodiment, the back yoke 23 is a member formed by bending a rectangular plate-like member into a substantially L-shaped cross section, and includes a long flat plate portion 25 and a short flat plate portion 26. The flat plate portions 25 and 26 may have the same length. In addition, the magnetic sensor 21 and the bias magnet 22 are fixed to the long flat plate portion 25, and the tip surface 26a of the short flat plate portion 26 is opposed to the circumferential surface of the annular portion 11 of the tone ring 10. Conversely, the flat plate portion that fixes the magnetic sensor 21 and the bias magnet 22 may be short, and the flat plate portion that faces the annular portion 11 of the tone ring 10 may be long.

  Further, in the present embodiment, the front end surface 26a of the short flat plate portion 26 of the back yoke 23 is opposed to the circumferential surface of the annular portion 11 of the tone ring 10, but is opposed to other portions of the tone ring 10. You can also However, if it is made to oppose the part of the bearing width direction outer side which has the convex part 12 and the recessed part 13, the magnetic resistance of this part will also fluctuate and the waveform of the output signal output from the magnetic sensor 21 will not become a sine wave. The duty ratio and the like may be deteriorated. On the other hand, when facing the circumferential surface of the annular portion 11 of the tone ring 10 as in the present embodiment, the magnetic resistance of this portion is always constant, so that the magnetic sensing surface 21a of the magnetic sensor 21 faces the bearing. The magnetic sensor 21 can detect only the change in magnetoresistance due to the portion on the outer side in the width direction. Therefore, the waveform of the output signal output from the magnetic sensor 21 becomes a sine wave.

  Further, the type of the magnetic sensor 21 is not particularly limited, and any general magnetic sensor can be used without any problem, but a differential Hall IC is preferable. As shown in FIG. 7, the differential Hall IC is a magnetic sensor in which two detection elements (Hall elements) are arranged at regular intervals in a package. In this differential Hall IC, the difference in magnetic force between the magnetic fluxes that have passed through the two detection elements is output as an output signal.

As shown in FIG. 7, the magnetic flux that has passed through the two detection elements is detected as an offset waveform. The waveforms obtained from the two detection elements have a certain phase difference, and when the difference is taken, the waveform is centered on zero. The offset waveform is converted into a pulse waveform at an arbitrary threshold level and output.
When the detection is performed using the tone ring 10 and the bias magnet 22 as in the present invention, the magnetic flux flows only in one direction (the illustrated direction or the opposite direction) as shown in FIGS. Need to be detected. In order to detect rotation based on the strength of magnetic force using a single magnetic sensor, it is necessary to accurately manage the magnetic strength of the bias magnet 22 in accordance with the threshold level. However, when a differential Hall IC is used, the differential signal is output at the center of zero, so that a pulse signal can be reliably obtained if an output waveform equal to or higher than the threshold level is obtained. Therefore, it is not necessary to manage the magnetic strength of the bias magnet 22 so accurately.

  Furthermore, it is sufficient to attach one detection unit 20, but two or more detection units 20 may be attached. When two or more detection units 20 are attached, it is desirable to consider their circumferential positions. For example, when two detectors 20 are installed, if the phase difference between the output signals obtained from both detectors 20 is 90 °, it can be used for determining the rotation direction, switching the energization of the motor, and the like. Become.

Further, the type of the bias magnet 22 is not particularly limited, and can be appropriately selected from rare earth magnets, ferrite magnets, and the like. However, the use of a rare earth magnet having a stronger magnetic force is more stable from the magnetic sensor 21. This is preferable because an output signal can be obtained.
Further, as the material for the sensor housing, a non-metallic material such as resin is preferable, but a resin material in which a fiber reinforcing material such as glass fiber is mixed with engineering plastic such as 66 nylon is more preferable.

Furthermore, as a method for fixing the sensor housing and the outer ring 2, a conventional fixing method such as adhesion can be adopted without any problem. In the case of fixing by adhesion, the type of adhesive (for example, a silicone-based adhesive) may be appropriately selected according to the use conditions of the rolling bearing with a rotation sensor.
Furthermore, in the present embodiment, the sensor housing is exposed to the outside, but in order to protect it from the influence of external force or the like, the outside may be covered with a cover such as metal.

  Furthermore, in the present embodiment, a deep groove ball bearing has been described as an example of a rolling bearing, but the present invention can be applied to various types of rolling bearings. For example, radial rolling bearings such as angular contact ball bearings, self-aligning ball bearings, self-aligning roller bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, and thrust types such as thrust ball bearings and thrust roller bearings This is a rolling bearing.

DESCRIPTION OF SYMBOLS 1 Inner ring 1a Raceway surface 2 Outer ring 2a Raceway surface 3 Rolling body 10 Tone ring 11 Annular part 12 Convex part 20 Detection part 21 Magnetic sensor 21a Magnetic detection surface 22 Bias magnet 23 Back yoke 25 Long flat plate part 26 Short flat plate part 26a Tip surface

Claims (3)

A plurality of rolling elements that are rotatably arranged between a rotatable rotating wheel, a fixed wheel that rotatably supports the rotating wheel, and a raceway surface that the rotating wheel has and a raceway surface that the fixed wheel has. In a rolling bearing with a rotation sensor comprising: a rotation sensor that detects rotation of the rotating wheel;
The rotation sensor includes a detected part made of an annular member made of a magnetic material attached to the rotating wheel so as to be rotatable integrally with the rotating wheel, and a fixed part attached to the fixed wheel via a gap. And at least one detection unit arranged opposite to each other in the radial direction, and the detection unit is arranged between the magnetic back yoke, the magnetic sensor, and the back yoke and the magnetic sensor. A bias magnet, and
With a rotation sensor, wherein a magnetic circuit is formed by the detection unit and the detected unit, and the rotation of the detected unit accompanying rotation of the rotating wheel is detected by the detection unit Rolling bearing. The back yoke is bent to have a substantially L-shaped cross section, one end of which is opposed to the annular member in the radial direction through a gap, and the bias magnet is disposed in the vicinity of the other end. ,
The annular member includes an annular portion whose entire circumferential surface can be opposed to the one end portion of the back yoke in a radial direction via a gap, and a plurality of convex portions projecting in a direction along the bearing central axis from the annular portion. 2. The rotation sensor according to claim 1, wherein the rotation sensor is provided at equal intervals in the direction, and the convex portion can be opposed to a magnetic detection surface of the magnetic sensor in a radial direction through a gap. Rolling bearing with.   The rolling bearing with a rotation sensor according to claim 1 or 2, wherein the magnetic sensor is a differential Hall IC.

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