JP2009097995A - Magnetic encoder and rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic encoder capable of detecting magnetic force appropriately. <P>SOLUTION: The magnetic encoder 16 includes a multipolar magnet 23 made of rubber where magnetic poles are arranged circumferentially and alternately. The multipolar magnet 23 is formed by performing heating compression molding to unvulcanized magnetic rubber containing a rubber composition, magnetic powder, and a curing agent while applying a magnetic field in a prescribed direction. The density of the multipolar magnet 23 is not less than 3.40 g/cm<SP>3</SP>and not more than 3.80 g/cm<SP>3</SP>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnetic encoder and a rolling bearing, and more particularly to a magnetic encoder including a rubber multipole magnet and a rolling bearing including such a magnetic encoder.

  2. Description of the Related Art Conventionally, as a bearing used in an automobile ABS (Antilock Break System) apparatus, there is a rolling bearing with a seal provided with a magnetic encoder. Such a rolling bearing is disclosed in, for example, JP-A-6-281018 (Patent Document 1). According to Patent Document 1, a rotation detection device that detects a rotation speed and a rotation direction includes a magnetic encoder and a sensor. The magnetic encoder includes a rubber multipole magnet having magnetic poles alternately formed in the circumferential direction, and a slinger that holds the magnet. The sensor detects alternating magnetic poles of a magnetic encoder that rotates with the rotating shaft. In this way, the rotation detection device detects the number of rotations and the like.

Here, when used for the above-mentioned automobiles and the like, there is a risk that the multipolar magnet and the foreign matter such as dust from the road rub against each other and the surface of the multipolar magnet may be worn. If it does so, a sensor cannot detect the magnetic pole of a multipole magnet appropriately. According to Japanese Patent Laid-Open No. 2002-333033 (Patent Document 2), a protective cover is provided on the outer side of the magnetic encoder. FIG. 9 is a cross-sectional view showing the magnetic encoder shown in Patent Document 2. As shown in FIG. Referring to FIG. 9, the ball bearing 101 includes an outer member 102, an inner member 103, a rolling element 104, a seal 105 that seals the bearing, and a magnetic encoder 106 that is attached to the inner member 103. . The magnetic encoder 106 includes a slinger 107 and a multipolar magnet 108 held by the slinger 107. Further, the ball bearing 101 includes a protective cover 109 attached to the outer side of the bearing of the multipolar magnet 108 so as to cover the multipolar magnet 108. This protective cover 109 reduces wear of the multipolar magnet 108 due to contact with foreign matter.
JP-A-6-281018 JP 2002-333033 A

  When the protective cover is attached to the outer side of the multipolar magnet as in Patent Document 2, a space for providing the protective cover is required between the sensor and the multipolar magnet, and the gap (interval) between the sensor and the multipolar magnet is required. Will become bigger. As described above, when the distance between the sensor and the multipolar magnet becomes long, the sensor may not be able to properly detect the magnetism of the multipolar magnet.

  An object of the present invention is to provide a magnetic encoder capable of appropriately detecting a magnetic force.

  Another object of the present invention is to provide a rolling bearing capable of appropriately detecting the rotational speed and the like.

The magnetic encoder according to the present invention includes a rubber multipole magnet in which magnetic poles are alternately arranged in the circumferential direction. The multipolar magnet is formed by heat compression molding an unvulcanized magnetic rubber containing a rubber composition, magnetic powder and a vulcanizing agent while applying a magnetic field in a predetermined direction. The density of the multipolar magnet is 3.40 g / cm ³ or more and 3.80 g / cm ³ or less.

  A magnetic encoder formed by heating and compression molding unvulcanized magnetic rubber while applying a magnetic field and the density of the multipolar magnet is in the above range has good moldability and excellent magnetic properties. . Therefore, in such a magnetic encoder, the magnetic force is appropriately detected by the sensor.

  Preferably, the rubber composition includes NBR (acrylonitrile-butadiene rubber). Moreover, it is preferable that NBR contains medium-high nitrile rubber.

  More preferably, the magnetic powder includes a ferrite magnetic powder for magnetic field orientation.

  In another aspect of the present invention, the rolling bearing is disposed between the outer ring, the inner ring, the outer ring and the inner ring, and rolls on the respective raceway surfaces provided on the outer ring and the inner ring, One of the magnetic encoders.

  Since such a rolling bearing can detect the magnetic force of the multipolar magnet contained in a magnetic encoder appropriately, it can detect rotation speed etc. appropriately.

  Preferably, it includes a protective cover that is attached to the bearing outer side of the magnetic encoder and is made of a nonmagnetic material.

  According to the present invention, a magnetic encoder formed by heating and compression molding an unvulcanized magnetic rubber while applying a magnetic field and the density of the multipolar magnet is in the above-described range has good moldability and magnetic properties. Excellent characteristics. Therefore, in such a magnetic encoder, the magnetic force is appropriately detected by the sensor.

  Moreover, since such a rolling bearing can detect the magnetic force of a multipolar magnet appropriately, it can detect rotation speed etc. appropriately.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a part of a rolling bearing including a magnetic encoder according to an embodiment of the present invention. With reference to FIG. 1, the rolling bearing 11 supports a rotating shaft (not shown). Such a rolling bearing 11 is used as a bearing for supporting the axle of an automobile.

  The rolling bearing 11 includes a ball 12 as a rolling element, an inner ring 13 disposed on the inner diameter side of the ball 12, an outer ring 14 disposed on the outer diameter side of the ball 12, and a cage (not shown). 2), a magnetic encoder 16 for detecting the rotational speed of the rotary shaft, and a seal 17 for sealing the inside of the bearing. The inner ring 13 is fixed to the rotating shaft and rotates together with the rotating shaft. On the other hand, the outer ring 14 is fixed to a housing (not shown). The ball 12 rolls on the raceway surfaces 15a and 15b provided on the inner ring 13 and the outer ring 14 when the rotary shaft rotates.

  The seal 17 includes a cored bar 31 having rigidity and a rubber part 32 having elasticity. The cored bar 31 is attached and fixed to the outer ring 14. The rubber part 32 is configured to cover a part of the cored bar 31. The rubber portion 32 is in contact with a slinger 24 described later at a plurality of locations with appropriate pressure. Specifically, a plurality of lip portions protruding to the inner diameter side of the seal 17 or the bearing outer side are in contact with the slinger 24. In this way, the inside of the rolling bearing 11 is sealed. By doing so, it is possible to prevent leakage of the lubricating oil sealed in the interior and prevent foreign matter from entering the rolling bearing 11.

  A rotation detection device 21 that detects the number of rotations of the rotation shaft and the like includes a magnetic encoder 16 included in the rolling bearing 11 and a rotation sensor 22. The magnetic encoder 16 and the rotation sensor 22 are provided at positions facing each other. The rotation sensor 22 is fixed to the housing together with the outer ring 14 and the like, for example.

  Here, the configuration of the magnetic encoder 16 will be described. The magnetic encoder 16 includes a rubber multipole magnet 23 in which magnetic poles are alternately arranged in the circumferential direction, and a metal slinger 24 that holds the multipole magnet 23. The slinger 24 includes a cylindrical portion 28a and a flange 28b extending from the one end of the cylindrical portion 28a to the outer diameter side. The multipolar magnet 23 is held on the outer side of the flange 28b.

  FIG. 2 is a conceptual diagram showing the configuration of the multipolar magnet 23. Referring to FIGS. 1 and 2, multipolar magnet 23 is annular and has a through hole at the center thereof. The multipolar magnet 23 is magnetized in a multipolar manner in the circumferential direction, and is configured such that N poles 27 a and S poles 27 b are alternately arranged on a PCD (Pitch Circle Diameter) 26.

  The multipolar magnet 23 held by the slinger 24 rotates with the inner ring 13 as the rotation shaft rotates. At this time, the change in the magnetic force of the N pole 27 a and the S pole 27 b of the multipolar magnet 23 is read by the detection unit 25 of the rotation sensor 22 disposed on the outer side in the axial direction and facing the multipolar magnet 23. In this way, the rotation detection device 21 detects the number of rotations of the rotation shaft and the like.

  In addition, you may decide to provide the protective cover comprised from a nonmagnetic material in the bearing outer side of the multipolar magnet 23, ie, the side in which the rotation sensor 22 is located so that the multipolar magnet 23 may be covered. By doing so, wear of the multipolar magnet 23 due to contact with foreign matter such as dust can be reduced. In this case, as will be described later, since the magnetic characteristics of the multipolar magnet 23 are good, even if the distance between the multipolar magnet 23 and the detection unit 25 is increased, the detection unit 25 appropriately The change in the magnetic force of 23 can be read. Further, since the distance between the multipolar magnet 23 and the detection unit 25 is long, it is possible to easily discharge the trapped sand dust and the like.

  Next, the configuration of the manufacturing apparatus for the magnetic encoder 16 will be described. FIG. 3 is a schematic sectional view of a manufacturing apparatus for the magnetic encoder 16. In FIG. 3 and the like, the upper side of the drawing is the upward direction. With reference to FIG. 3, the magnetic encoder manufacturing apparatus 51 can perform heat compression molding while applying a magnetic field. The magnetic encoder manufacturing apparatus 51 includes a press 52 as pressurizing means for applying pressure, a movable shaft 55a attached to the movable plate 54a, a support column 53 supporting the movable plate 54a, and a fixed shaft attached to the fixed plate 54b. 55b. A press 52 is attached above the movable plate 54a. With the press 52, the movable plate 54a and the movable shaft 55a can move downward and load a load.

  The magnetic encoder manufacturing apparatus 51 is attached to the distal ends of the movable shaft 55a and the fixed shaft 55b, and a mold core 71 as a housing portion that houses unvulcanized magnetic rubber that is a material of a multipolar magnet described later. A mold part 60 disposed around the mold core 71, a heater 58 disposed around the mold part 60 as a heating means for heating the mold part 60 and the mold core 71, A heat insulating plate 59 arranged in the vertical direction of the mold part 60 to block heat transfer from the mold part 60, a cooling jacket pipe 57 arranged in the vertical direction of the heat insulating plate 59, and the cooling jacket pipe 57 above and below And a coil 56 as magnetic field generation means for generating a magnetic field in a predetermined direction.

  The cooling jacket tube 57 as a cooling means cools the coil 56 with the refrigerant from the cooler 62 sent through the pipe 61. The heat insulating plate 59 reduces heat transfer from the mold part 60 to the coil 56. In addition, the support | pillar 53, the movable plate 54a, the fixed plate 54b, the movable shaft 55a, and the fixed shaft 55b are comprised with the magnetic material, and the cooling jacket pipe | tube 57 and the metal mold | die part 60 are comprised with the nonmagnetic material. In FIG. 3, the hatched portion is a member made of a magnetic material.

  FIG. 4 is a cross-sectional view of the mold core 71. FIG. 5 is a perspective view of the mold core 71. FIG. 6 is a perspective view of the lower mold core 72 b included in the mold core 71. Referring to FIGS. 3 to 6, a mold core 71 is composed of an upper mold core 72a and a lower mold core 72b, each having a disk shape. A recess 75a that is recessed in the thickness direction is provided at the center of the upper mold core 72a. A convex portion 75b that swells in the thickness direction is provided at the center of the lower mold core 72b. The mold core 71 is disposed so as to fit the concave portion 75a provided in the upper mold core 72a and the convex portion 75b provided in the lower mold core 72b. The outer shape of the multipolar magnet 23 is formed by the upper mold core 72a and the lower mold core 72b.

  The upper mold core 72a and the lower mold core 72b are composed of a magnetic material 74 and a nonmagnetic material 73, respectively. The nonmagnetic material 73 is disposed on the radial center side and the outer diameter side of the upper mold core 72a and the lower mold core 72b, and the magnetic material 74 is sandwiched between the nonmagnetic materials 73 in the radial direction. Placed in the part. When the upper mold core 72a and the lower mold core 72b are fitted together, the magnetic materials 74 and the nonmagnetic materials 73 are positioned in the vertical direction, respectively. The position where the magnetic materials 74 provided in the upper mold core 72a and the lower mold core 72b are closest to each other is preferably close to the center in the radial direction in the region where the magnetic material 74 is located. By doing so, the magnetic flux density can be increased at this position when the magnetic rubber is vulcanized.

  In the lower mold core 72b, a portion made of the magnetic material 74 is recessed in the thickness direction, and the slinger 64 can be attached. When the lower mold core 72b to which the slinger 64 is attached is fitted to the upper mold core 72a, the magnetic material 74 is disposed in the vertical direction of the slinger 64. In this case, the slinger 64 is attached with the surface 65 holding the multipolar magnet as the upper side.

  Note that, from the viewpoint of easy understanding, the magnetic encoder manufacturing apparatus 51 shown in FIG. 3 is configured to include one mold core 71, but by attaching a plurality of mold cores 71, the magnetic encoder can be It can be molded at the same time. That is, it is possible to form a plurality of magnetic encoders by one molding so that a plurality of mold cores 71 are arranged so as to be arranged in parallel in the left-right direction.

  By energizing the coil 56, a magnetic field can be generated in the magnetic encoder manufacturing apparatus 51. Here, as described above, since the members constituting the magnetic encoder manufacturing apparatus 51 are made of a magnetic material or a non-magnetic material, in the magnetic encoder manufacturing apparatus 51, an arrow III indicated by a one-dot chain line in FIG. Magnetic field loops can be formed in the direction. In this way, heat compression molding is performed with the magnetic field at a predetermined position in the mold core 71, specifically, a portion made of the magnetic material 74 being dense. By doing so, the magnetic powder contained in the magnetic rubber can be highly oriented during the heat compression molding. In such heat compression molding, the magnetic powder can be oriented along the magnetic field in each part of the magnetic rubber during the flow of the material, that is, the unvulcanized magnetic rubber. Here, according to injection molding using a magnetic field, for example, the magnetic powder is oriented in a direction different from the direction of the magnetic field on the end portion side where the material flows. However, such fear can be reduced by heat compression molding.

  Next, a method for manufacturing the magnetic encoder 16 will be described. First, after the mold core 71 is heated to the vulcanization temperature by the heater 58, the slinger 64 is disposed in the mold core 71. Here, a vulcanizing adhesive is applied in advance to the surface 65 of the slinger 64 where the magnetic rubber is located. Next, the unvulcanized magnetic rubber 63 prepared in advance is set on the upper side of the slinger 64 in the lower mold core 72b, that is, on the surface 65 side where the vulcanized adhesive is applied. As shown in FIG. 7, the unvulcanized magnetic rubber 63 is temporarily formed into a ring shape temporarily.

  Thereafter, the movable plate 54a is moved downward and pressurized, and the magnetic rubber 63 is heated and compressed. Here, the coil 56 is energized to generate a magnetic field, and molding is performed while the magnetic field is applied. After a predetermined time elapses, energization of the coil 56 is stopped. Thereafter, the movable plate 54 a is moved upward, and the magnetic encoder is removed from the mold core 71. In this case, the magnetic rubber 63 is adhered and held on the surface 65 of the slinger 64 by a vulcanizing adhesive. Thereafter, the vulcanized magnetic rubber 63 is heat-treated at a predetermined temperature and for a predetermined time as necessary, and is magnetized into a multipolar magnet by a magnetizing yoke to obtain a desired magnetic encoder.

Here, it is preferable that the density of the obtained multipolar magnet, that is, the density of the vulcanized magnetic rubber is 3.40 g / cm ³ or more and 3.80 g / cm ³ or less. This is because if the density is less than 3.40 g / cm ³ , the magnetic force may not be properly detected when the protective cover is attached and the gap becomes large. Moreover, when the density is higher than 3.80 g / cm ³ , it is difficult to mold by heat compression molding, and the moldability may be deteriorated. The density of the multipolar magnet depends on the material used and the blending ratio. For example, the desired value can be obtained by changing the content of the magnetic powder.

  Next, the magnetic rubber constituting the multipolar magnet included in the magnetic encoder will be described. As described above, the multipolar magnet is formed by heat-compressing unvulcanized magnetic rubber and magnetizing the vulcanized magnetic rubber to multipolar. Unvulcanized magnetic rubber contains a rubber composition, magnetic powder, softener (process oil), zinc white, anti-aging agent, internal mold release agent, vulcanizing agent and co-crosslinking agent. By including the internal mold release agent, it is possible to improve die wear and the like. The rubber composition includes a solid rubber and a liquid rubber.

  Here, as the rubber composition, natural rubber, polyisobutylene, polyisoprene, isoprene-isobutylene rubber (butyl rubber), styrene-butadiene rubber, styrene-isobutylene-styrene rubber (SBS), styrene-isoprene-styrene rubber (SIS) , Styrene-ethylene-butylene-styrene rubber (SEBS), ethylene-propylene terpolymer (EPDM), acrylonitrile-butadiene rubber (NBR), hydrogenated NBR (H-NBR), fluoro rubber, silicone rubber, acrylic rubber, chloroprene rubber Chlorosulfonated polyethylene, epichlorohydrin rubber, urethane rubber, polysulfide rubber and the like.

  Note that NBR, H-NBR, and acrylic rubber are preferable as the above-described magnetic encoder for automobiles. NBR is very high nitrile rubber (nitrile group content 43 wt% or more), high nitrile rubber (nitrile group content 36-42 wt%), medium-high nitrile rubber (nitrile group content) depending on nitrile group content 31 to 35 wt%), medium nitrile rubber (nitrile group content 25 to 30 wt%), and low nitrile rubber (nitrile group content 24 wt% or less). When used in the above applications, the nitrile group content is preferably 31% by weight or more from the viewpoint of improving oil resistance. Furthermore, considering the cost and the like, it is preferable to use a medium-high nitrile rubber. Examples of commercially available NBR include Nipol 1042 (medium-high nitrile), Nipol 1041 (high nitrile), Nipol 1043 (medium nitrile), Nipol 1312 (liquid NBR) (all manufactured by Nippon Zeon Co., Ltd.), and the like.

  As the vulcanizing agent for vulcanizing the unvulcanized magnetic rubber, it is preferable to use a peroxide vulcanizing agent. By doing so, the unvulcanized magnetic rubber can be vulcanized by low-temperature vulcanization. If it does so, a magnetic encoder can be manufactured, suppressing a temperature rise at the time of heat compression molding. Therefore, continuous molding considering mass productivity can be performed, and the productivity of the magnetic encoder can be improved.

  As the peroxide vulcanizing agent when NBR is used as the rubber composition, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxyester, peroxydicarbonate, A diacyl peroxide vulcanizing agent may be mentioned. In particular, the peroxyketal system is preferable for the low-temperature vulcanization as described above. Moreover, it is preferable to contain 10 weight part or more of the mixture with respect to 100 weight part of solid rubber. Examples of commercially available peroxyketal crosslinking agents include perhexa C40 (1,1 di (t-butylperoxy) cyclohexane, manufactured by Nippon Oil & Fats Co., Ltd.). Moreover, as a commercial item of a diacyl peroxide type | system | group crosslinking agent, Perkadox CH-50L (Dibenzoyl peroxide, Kayaku Akzo Co., Ltd. product) etc. are mentioned.

  Moreover, sulfur can also be used as a vulcanizing agent. Examples of commercially available sulfur include sulfur (manufactured by Tsurumi Chemical Co., Ltd.). Further, a vulcanization accelerator may be used. Examples of the vulcanization accelerator include a titanium-based vulcanization accelerator. As a commercial item of a Tiraum vulcanization accelerator, Noxeller TT, Noxeller CZ (both manufactured by Ouchi Shinsei Chemical Co., Ltd.) and the like can be mentioned.

  A co-crosslinking agent may be used in combination with the vulcanizing agent. By doing so, the magnetic rubber can be vulcanized more efficiently. Examples of the co-crosslinking agent include amine polysulfide series, bismaleimide series, thiraum series, higher methacrylic acid esters, metal salts of methacrylic acid, and triazine thiol series. In particular, a bismaleimide co-crosslinking agent is preferred for use in the low-temperature vulcanization as described above. Moreover, it is preferable to contain 10 weight part or more of the mixture with respect to 100 weight part of solid rubber. Examples of commercially available bismaleimide co-crosslinking agents include Barnock PM (N, N′-m-phenylene bismaleimide, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.).

  In addition, as a commercially available softener (process oil), SYNTAC HA-35 (manufactured by Kobe Oil Chemical Co., Ltd.) and the like, as a commercial product of zinc white, zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd.), etc. In addition, as a commercial product of an anti-aging agent, as a commercial product of NOCRACK CD (4,4′-bis (α, α-dimethylbenzyl) diphenylamine, manufactured by Ouchi Shinsei Chemical Co., Ltd.), an internal mold release agent, EG-ROLL (manufactured by Sekiko Chemical Co., Ltd.) and the like. In addition, you may use a stearic acid etc. as an internal mold release agent.

  In addition, as described above, magnetic rubber is held by adhering to slinger with a vulcanizing adhesive during heat compression molding, and as a vulcanizing adhesive, a phenolic resin-based adhesive having a phenolic resin as an adhesive component is used. preferable. Examples of the phenol resin-based adhesive include adhesives containing novolac type phenol resins, resol type phenol resins, and mixtures of these phenol resins as adhesive components. The novolac type phenol resin can be obtained by reacting phenols with formaldehyde in the presence of an acidic catalyst (hydrochloric acid, oxalic acid, etc.). As phenols in this case, phenol, m-cresol, a mixture of m-cresol and p-cresol, bisphenol A and the like are used. The resol type phenol resin is obtained by reacting bisphenol A and formaldehyde in the presence of a basic catalyst (alkali metal, magnesium hydroxide, etc.).

  Commercially available phenolic resin adhesives include Sixson 715 (manufactured by Rohm and Haas), Metalloc N10, Metalloc N15, Metalloc N15D, Metalloc N31, Metalloc NT, Metalloc PA (all manufactured by Toyo Chemical Laboratories), Chemloc TS1677 -13 (manufactured by Rod Far East) and the like. Moreover, as an adhesive containing a phenol resin and an epoxy resin, METALOC XPH-27 (manufactured by Toyo Chemical Laboratory) and the like can be mentioned. Furthermore, examples of the adhesive containing a phenol resin and a synthetic rubber include METALLOCK C12, METALLOCK N20, METALLOCK N20D, METALLOCK N23, METALOC P (all manufactured by Toyo Chemical Laboratories) and the like.

  As the magnetic powder, hard ferrite and soft ferrite such as barium ferrite and strontium ferrite can be used. These ferrite powders may be granular powders or anisotropic ferrite powders. Further, in the above-described heat compression molding, anisotropic ferrite for magnetic field orientation having a particle shape with a smaller particle resistance during flow in the mold may be used. The magnetic powder may be a rare earth magnetic material. For example, any single magnetic powder of samarium iron (SmFeN) magnetic powder, neodymium iron (NdFeB) magnetic powder, or samarium-cobalt may be used. Further, a mixture of two or more of such rare earth magnetic powders may be used. Further, when the magnetic force is insufficient with only the above-described ferrite powder, rare earth magnetic powder such as samarium iron-based magnetic powder or neodymium iron-based magnetic powder may be mixed with the ferrite powder. By doing so, it can be manufactured at low cost while improving the magnetic force. Examples of commercially available ferrite products include FA600 (manufactured by Toda Kogyo Co., Ltd.).

  In addition, it is preferable that content of magnetic powder shall be 1350 weight part or more with respect to 100 weight part of solid rubber. By doing so, a higher magnetic flux density can be obtained. On the other hand, when the content ratio is high, the amount of the rubber component as the binder is relatively lowered, and the moldability is deteriorated. Therefore, the content of the magnetic powder is preferably less than 1800 parts by weight.

  The strength of the magnetic field applied during heat compression molding is preferably 80000 A / m or more and 800000 A / m or less. This is because if it is less than 80000 A / m, the magnetic flux density of the obtained magnetic encoder may be lowered. Further, the magnetic field is saturated at about 800,000 A / m, and if the magnetic field is larger than 800,000 A / m, heat generation of the coil increases.

  Here, Tables 1 and 2 show the composition and evaluation of the magnetic encoder. The molding conditions and the like are shown below.

  As for molding conditions, the magnetic rubber was set in a mold heated to 150 ° C., the mold was closed, and immediately after heating and compression, applied at 100000 A / m for 20 minutes to apply a magnetic field. After stopping the application of the magnetic field, it was held in the mold for another 10 minutes. The heat compression molding was performed for a total of 30 minutes.

The density measurement is as follows. Measurement was performed using a pycnometer (specific gravity bottle, nominal volume 50 ml) shown in JIS R3503. First, wash the vessel, the mass was measured M ₁ of the container is dried. The amount of magnetic rubber scraped off by the magnetic encoder was put into this container up to about 1/4 of the height of the container, and the mass M ₂ at that time was measured. The mass (M ₁ -M ₂ ) is the mass of the magnetic rubber itself. Next, a little more distilled water was added to the container containing the magnetic rubber than the magnetic rubber powder was completely immersed, and this state was put into the vacuum container. Then, the vacuum vessel was depressurized to about 10 kPa to deaerate the air adhering to the particles, and this deaeration was performed until no bubbles were generated from the magnetic rubber powder. Then, after taking out from a vacuum vessel and leaving to stand until the liquid temperature became room temperature, distilled water was added to the specified amount of the vessel, and the mass M ₃ at that time was measured. Next, the magnetic rubber and distilled water were taken out from the container, washed and dried, and then again with distilled water up to a specified amount, and the mass M ₄ was measured. Separately, the density ρ _L of distilled water at the measurement temperature was obtained by interpolating from Table 5.2 of Chapter 5 of the Basic Guide to Chemical Handbook (Revised 4th edition, published by Maruzen Co., Ltd.). The density ρ (g / cm ³ ) of the magnetic rubber was calculated by the following equation (1).

  As for moldability, whether or not it can be appropriately molded as a multipolar magnet by the above-described heat compression molding was evaluated, and those that could be properly molded were indicated by ◯, and those that could not be molded were indicated by ×.

  For magnetic properties, the magnetic encoder (outer diameter φ78 mm, inner diameter φ68 mm, magnetic rubber part thickness 1.1 mm) obtained by the above-described heat compression molding is magnetized to 45 to 90 poles, and then the thickness is 0.4 mm. A SUS protective cover was attached, and the magnetic flux density was measured at a gap of 2.0 mm from the surface of the protective cover using a magnetic property inspection apparatus TMW-EC14L (manufactured by Toyo Magnetic Industry Co., Ltd.). In the table, ◯ is 5 mT or more, and x indicates a value lower than 5 mT.

  For oil resistance test, JIS No. Using an IRM 903 corresponding to oil No. 3, the volume change rate after immersion for 72 hours at 100 ° C. was used. In the table, ○ indicates ± 5% or less, and × indicates a case where ± 5% is exceeded.

Referring to Table 1 to Table 2, the density is less than 3.40 g / cm ³ or more 3.80 g / cm ³ No. 1-No. 8, no. 13, no. No. 14 has good moldability and magnetic properties. On the other hand, No. having a density of less than 3.40 g / cm ³ . 9, no. 11 has poor magnetic properties. In addition, No. having a density greater than 3.80 g / cm ³ . 10, no. No. 12, the moldability is inferior. In addition, No. About 14, oil resistance is inferior. Therefore, when it is used for the above-mentioned automobile, it is preferable to select one having good oil resistance.

  A rolling bearing including such a magnetic encoder is provided in a support structure for an automobile axle. FIG. 8 is a schematic cross-sectional view showing an axle support structure. Referring to FIG. 8, axle support structure 81 includes a hub wheel 82 that rotates together with an axle (not shown), and a rolling bearing 91 that supports the axle. The flange 84 of the hub wheel 82 is fixed to a wheel (not shown) by a bolt 83. The rolling bearing 91 is a double row angular ball bearing, and includes balls 92 arranged in a double row, an inner ring 93, an outer ring 94, a retainer 95, a seal 96, and a magnetic encoder (not shown). .

  The inner ring 93 is fixed to the hub wheel 82 and rotates with the rotation of the axle. The outer ring 94 is fixed to a housing (not shown) disposed on the outer diameter side. Further, the seal 96 includes a magnetic encoder including a multipolar magnet and a slinger, and the rotation sensor 97 can detect the rotation speed.

  Thus, the axle support structure 81 is configured. Such an axle support structure 81 has good productivity.

  In addition, in said embodiment, although the case where a ball was used as a rolling element was demonstrated, it applies, also when using rollers, such as a cylindrical roller, a needle roller, and a rod roller, as a rolling element. The present invention is also applied to a rolling bearing that does not include a seal, and a rolling bearing that does not include an outer ring or an inner ring.

  Moreover, although the above-mentioned magnetic encoder was included in the rolling bearing, it may be included in not only this but a sliding bearing. Furthermore, the present invention is not limited to the rotating shaft and the like, and may be applied when detecting the rotational speed or the like of another rotating member, and may constitute a rotation detecting device that detects the rotational speed or the like of the rotating member together with the detection sensor. .

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  The magnetic encoder and the rolling bearing according to the present invention are effectively used for a rolling bearing for an axle such as an automobile.

It is sectional drawing which shows a part of rolling bearing which concerns on one Embodiment of this invention. It is a conceptual diagram which shows the structure of a multipolar magnet. It is a schematic sectional drawing of a magnetic encoder manufacturing apparatus. It is sectional drawing of the metal mold | die core contained in a magnetic encoder manufacturing apparatus. It is a perspective view of the metal mold | die core contained in a magnetic encoder manufacturing apparatus. It is a perspective view of the lower mold core which comprises the mold core contained in a magnetic encoder manufacturing apparatus. It is a perspective view which shows the shape | molded unvulcanized magnetic rubber. It is a schematic sectional drawing which shows the axle shaft support structure containing the rolling bearing which concerns on one Embodiment of this invention. It is sectional drawing which shows a part of conventional ball bearing.

Explanation of symbols

  11,91 Rolling bearing, 12,92 Ball, 13,93 Inner ring, 14,94 Outer ring, 15a, 15b Raceway surface, 16 Magnetic encoder, 17,96 Seal, 21 Rotation detector, 22,97 Rotation sensor, 23 Multipole Magnet, 24, 64 Slinger, 25 Detector, 26 PCD, 27a N pole, 27b S pole, 28a, cylindrical part, 28b, 84 flange, 31 cored bar, 32 rubber part, 51 magnetic encoder manufacturing apparatus, 52 press, 53 Column, 54a Movable plate, Fixed plate 54b, 55a Movable shaft, 55b Fixed shaft, 56 Coil, 57 Cooling jacket tube, 58 Heater, 59 Thermal insulation plate, 60 Mold part, 61 Pipe, 62 Cooler, 63 Magnetic rubber, 65 surface , 71 Mold core, 72a Upper mold core, 72b Lower mold core, 73 Non-magnetic material 74 magnetic materials, 75a concave, 75b convex portion, 81 an axle support structure 82 hub wheel, 83 volts, 95 retainer.

Claims (6)

A magnetic encoder including a rubber multipole magnet in which magnetic poles are alternately arranged in a circumferential direction,
The multipolar magnet is formed by heat compression molding an unvulcanized magnetic rubber containing a rubber composition, magnetic powder and a vulcanizing agent while applying a magnetic field in a predetermined direction,
The magnetic encoder has a density of the multipolar magnet of 3.40 g / cm ³ or more and 3.80 g / cm ³ or less. The magnetic encoder according to claim 1, wherein the rubber composition includes NBR (acrylonitrile-butadiene rubber). The magnetic encoder according to claim 2, wherein the NBR includes medium-high nitrile rubber. The magnetic encoder according to any one of claims 1 to 3, wherein the magnetic powder includes a magnetic ferrite for magnetic field orientation. Outer ring,
Inner ring,
A rolling element that is disposed between the outer ring and the inner ring and rolls on a raceway provided in the outer ring and the inner ring;
A rolling bearing comprising the magnetic encoder according to claim 1. The rolling bearing according to claim 5, comprising a protective cover that is attached to the bearing outer side of the multipolar magnet so as to cover the multipolar magnet and is made of a nonmagnetic material.

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