JP2008039742A - Magnetic encoder and rolling bearing with rotation sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate no turbulence of a magnetic flux at a butted part of a band or string-like magnetic body saving metal mold cost for molding. <P>SOLUTION: No turbulence of the magnetic flux is generated at the butted part without surely eliminating a gap of the butted part of both end faces 3a of the magnetic body 3 by filling the butted part of both the end faces 3a of the string-like magnetic body 3 of a magnetic encoder 1 with an adhesive mixing a magnetic material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rolling bearing with a rotation sensor using a magnetic encoder and a magnetic encoder.

  In the rolling bearing with rotation sensor, a magnetic encoder magnetized alternately in the N and S poles in the circumferential direction is mounted on the rotating raceway side of the inner and outer raceways. There is one in which a magnetic sensor for detecting a change in magnetic flux accompanying the above is mounted on the stationary race ring side to detect the rotation of the rotary race ring (for example, see Patent Document 1).

  As the magnetic encoder, a magnetic material having a rubber binder is fixed to an annular cored bar and magnetized alternately in the circumferential direction in the N and S poles. It is mounted on a rotating raceway. In the embodiment described in Patent Document 1, a magnetic body using rubber as a binder is fixed to a core metal by vulcanization bonding, and the magnetic encoder is formed by magnetizing the vulcanization bonded magnetic body to N and S poles. Manufacture.

  In addition, the magnetic encoder has an annular shape so that the magnetic body is formed in a strip shape and both end faces thereof are abutted in order to save the molding die cost for vulcanizing and bonding the magnetic body to the core metal. There exists what was wound around the surrounding surface of the metal core and adhered (for example, refer to patent documents 2).

JP 2002-349556 A JP 2003-86420 A

  The magnetic encoder described in Patent Document 2 has an advantage that the manufacturing cost can be reduced by saving the molding die cost, but a gap is generated at the abutting portion of both end faces of the belt-like magnetic body, and the magnetic body is abutted. There is a problem that the magnetic flux is easily disturbed at the portion, and the rotation speed cannot be accurately detected by the magnetic sensor.

  Therefore, an object of the present invention is to prevent the magnetic flux from being disturbed at the butt portion of the band-like or string-like magnetic body that can save the molding die cost.

  In order to solve the above-mentioned problems, the present invention wraps a magnetic material formed by mixing a magnetic material with rubber into a band shape or a string shape around a circumferential surface of an annular cored bar so that both end surfaces thereof abut each other. In the magnetic encoder in which the N pole and the S pole are alternately magnetized in the circumferential direction, a configuration in which an adhesive mixed with a magnetic material is filled in the abutting portions of both end faces of the magnetic body is adopted.

  That is, by filling the abutting portions of both end faces of the belt-like or string-like magnetic body with an adhesive mixed with a magnetic material, the gaps at the abutting portions of both end faces of the magnetic body are surely eliminated, and In order not to disturb the magnetic flux.

  By making the blending ratio of the magnetic material mixed in the adhesive equal to the blending ratio of the magnetic material mixed in the magnetic body, it is possible to prevent the magnetic flux from being disturbed more in the butt portion.

  By making the both end surfaces of the butt portion of the magnetic body into inclined surfaces that are inclined in the axial direction or thickness direction, the butt portion formed perpendicular to the rotation direction is eliminated, and magnetic flux disturbance at the butt portion is more reliably ensured. Can be prevented.

  After the magnetic body is bonded to the peripheral surface of the cored bar, the accuracy of the magnetization interval between the magnetic poles can be increased by magnetizing the N pole and the S pole.

  Further, according to the present invention, a magnetic encoder magnetized alternately with N and S poles in the circumferential direction is mounted on the rotating raceway side of the inner and outer raceways, and the magnetic encoder is rotated. In a rolling bearing with a rotation sensor for mounting a magnetic sensor for detecting a change in magnetic flux on the fixed race ring side and detecting the rotation of the rotary race ring, a configuration using any one of the magnetic encoders described above as the magnetic encoder. By adopting it, magnetic flux disturbance is prevented from occurring at the abutting part of the magnetic body of the magnetic encoder, and the rotational speed can be accurately detected by the magnetic sensor.

  In the magnetic encoder of the present invention, the adhesive portion mixed with the magnetic material is filled in the abutting portions of both end faces of the belt-like or string-like magnetic body, so that the molding die cost can be saved and both end faces of the magnetic body can be saved. It is possible to reliably eliminate the gap at the abutting portion so that the magnetic flux is not disturbed at the abutting portion, and the rotation speed can be accurately detected by the rotation sensor.

  By making the blending ratio of the magnetic material mixed in the adhesive equal to the blending ratio of the magnetic material mixed in the magnetic body, it is possible to prevent the magnetic flux from being disturbed more in the butt portion.

  By making both end faces of the abutting portion of the magnetic body into inclined surfaces that are inclined in the axial direction or the thickness direction, the abutting portion formed perpendicular to the rotation direction is eliminated, and the turbulence is more reliably disturbed at the abutting portion. Can be prevented.

  After adhering the magnetic body to the peripheral surface of the cored bar, the accuracy of the magnetizing interval between the magnetic poles can be increased by magnetizing the N pole and the S pole.

  In addition, since the rolling bearing with a rotation sensor of the present invention uses any one of the magnetic encoders described above as a magnetic encoder, it is possible to save the molding die cost and to disturb the magnetic flux at the butt portion of the magnetic body of the magnetic encoder. And the rotational speed can be accurately detected by the magnetic sensor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a rolling bearing with a rotation sensor using a magnetic encoder 1 according to the present invention. This rolling bearing with a rotation sensor is a deep groove ball bearing in which a plurality of balls 23 are held by a cage 24 between an inner ring 21 as a rotating race and an outer ring 22 as a fixed race, and a seal 25 is provided at one end. At the other end, the annular cored bar 2 of the magnetic encoder 1 is fitted to the outer diameter surface of the inner ring 21, and the outer ring 4 fitted to the inner diameter surface of the outer ring 22 is opposed to the magnetic encoder 1. A sensor case 6 that houses the magnetic sensor 5 is fitted. An output cable 7 for outputting a change in magnetic flux detected by the magnetic sensor 5 is connected to the sensor case 6.

  As shown in FIGS. 2 (a) and 2 (b), the magnetic encoder 1 abuts both end surfaces 3a of a magnetic body 3 obtained by mixing a rubber with a magnetic material and vulcanizing and forming a string having a rectangular cross section. In this way, both end surfaces 3a of the magnetic body 3 are made to be inclined surfaces inclined in the axial direction, and the abutting portions of both end surfaces 3a between the inclined surfaces are attached to each other. The adhesive A mixed with a magnetic material is filled, and the both end faces 3a are bonded without a gap. The magnetic material mixed in the adhesive A is the same as the magnetic material of the magnetic body 3 described later, and is mixed at the same blending ratio. As the adhesive A, epoxy, acrylic, silicone, or the like can be used, and is not particularly limited. Note that the magnetic body 3 is alternately magnetized to the N and S poles in the circumferential direction after bonding so that the boundary between the N and S poles is aligned with the center of the butted portion.

  3A and 3B show a molding die 11 obtained by vulcanizing and molding the string-like magnetic body 3. The molding die 11 is provided with a spiral molding groove 11a on the upper surface, and a magnetic material and rubber are mixed and poured into the molding groove 11a so that the string-like magnetic body 3 has a spiral curvature. To be molded. Therefore, as shown in FIGS. 4A and 4B, the magnetic body 3 can be smoothly wound along the outer peripheral surface of the cored bar 2. In addition, as a magnetic material mixed with the magnetic body 3, those of ferrite type, samarium type, neodymium type, cobalt type, etc. can be used, and the rubber includes nitrile rubber, acrylic rubber, fluorine rubber, silicone rubber, etc. Can be used.

  4 (a) and 4 (b) show a procedure in which the string-like magnetic body 3 is wound around the cored bar 2 and bonded. First, as shown in FIG. 4 (a), a string-like magnetic body 3 is wound around the outer peripheral surface of the core metal 2 and both ends are overlapped, and about 3/4 of the circumference excluding the vicinity of both ends is the outer periphery of the core metal 2. Adhere to the surface. In this state, as shown in FIG. 4 (b), the overlapped both end portions are cut obliquely inclined in the axial direction, and the remaining ¼ circumference is adhered to the outer peripheral surface of the cored bar 2. As shown in 2 (b), the adhesive A is filled between the both end faces 3a cut obliquely, and these butt portions are bonded. In addition, when both end surfaces 3a are bonded to each other, if a step is generated on the outer diameter surface or the side surface of the butted portion, post-processing may be performed so as to remove the step.

  As an example, when the magnetic encoder 1 shown in FIGS. 2A and 2B is incorporated in the rolling bearing with a rotation sensor shown in FIG. 1 and the magnetic encoder 1 rotates together with the inner ring 21, the magnetic sensor 5 The magnetic waveform detected at 1 was measured. As a comparative example, the magnetic waveform when the magnetic encoder 1 not filled with the adhesive A was incorporated in the butted portion of the magnetic body 3 was also measured.

  FIGS. 5A and 5B show magnetic waveforms detected in the vicinity of the butt portion of the magnetic body 3 in the example and the comparative example, respectively. In any of the magnetic waveforms, the magnetic flux changes in a wave shape toward the N pole side and the S pole side each time the N pole and S pole of the magnetic encoder 1 alternately pass through the front surface of the magnetic sensor 5. In the comparative example shown in b) where the butt portion is not filled with the adhesive A, the magnetic waveform is disturbed near the butt portion. On the other hand, in the example shown in FIG. 5A in which the butt portion is filled with the adhesive A, the magnetic waveform is not disturbed in the vicinity of the butt portion, and the same normal magnetic waveform as other portions. Has been detected.

  In the above-described embodiment, both end surfaces that become the butt portion of the string-like magnetic body are inclined surfaces that are inclined in the axial direction. However, these both end surfaces are inclined surfaces that are inclined in the thickness direction, or vertical that has no inclination. It can also be a surface. The magnetic body may be a flat strip.

  In the above-described embodiment, the rolling bearing with a rotation sensor is a deep groove ball bearing and the inner ring is a rotating raceway. However, the rolling bearing with a rotation sensor according to the present invention is suitable for other types of rolling bearings such as a roller bearing. The outer ring can also be a rotating raceway.

Vertical front view showing a rolling bearing with a rotation sensor using a magnetic encoder according to the present invention a is a side view showing the magnetic encoder of FIG. 1, and b is a developed plan view showing an enlarged butted portion of the magnetic body of a. a is a plan view showing a molding die for molding the magnetic body of FIG. 2, b is a cross-sectional view taken along line IIIb-IIIb of a a and b are side views showing a procedure for winding and bonding the magnetic body of FIG. a and b are graphs showing magnetic waveforms detected in the vicinity of the butt portion of the magnetic material in the example and the comparative example, respectively.

Explanation of symbols

A Adhesive 1 Magnetic encoder 2 Core 3 Magnetic body 3a End face 4 Outer ring 5 Magnetic sensor 6 Sensor case 7 Output cable 11 Mold 11a Mold groove 21 Inner ring 22 Outer ring 23 Ball 24 Cage 25 Seal

Claims (5)

  A magnetic material formed by mixing rubber with a magnetic material in the shape of a band or string is wrapped around and bonded to the circumferential surface of an annular core metal so that both end faces thereof are in contact with each other. A magnetic encoder magnetized on an S pole, wherein an abutting portion between both end faces of the magnetic material is filled with an adhesive mixed with a magnetic material.   The magnetic encoder according to claim 1, wherein a blending ratio of the magnetic material mixed into the adhesive is equal to a blending ratio of the magnetic material mixed into the magnetic body.   3. The magnetic encoder according to claim 1, wherein both end surfaces of the butted portion of the magnetic body are inclined surfaces inclined in the axial direction or the thickness direction.   The magnetic encoder according to any one of claims 1 to 3, wherein the magnetic body is magnetized to the north and south poles after being bonded to the peripheral surface of the cored bar.   A magnetic encoder magnetized with N and S poles alternately in the circumferential direction is mounted on the rotating raceway side of the inner and outer raceways, and changes in magnetic flux accompanying the rotation of the magnetic encoder are detected. In a rolling bearing with a rotation sensor that mounts a magnetic sensor on the fixed race ring side and detects the rotation of the rotary race ring, the magnetic encoder according to any one of claims 1 to 4 is used for the magnetic encoder. A rolling bearing with a rotation sensor.

Images