JP2007101443A - Rolling bearing unit with magnetic encoder, and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing unit with a magnetic encoder capable of maintaining detection precision for a rotation speed or the like, even when a protection member is interposed, and capable of making damage prevention by the protection member compatible with magnetic performance. <P>SOLUTION: A magnetic pole forming ring 27 of the magnetic encoder 26 is an anisotropic magnet comprising a plastic magnetic material using a thermoplastic containing magnetic powder as a binder. A protection cover 30 comprising a nonmagnetic material is interposed between the magnetic pole forming ring 27 and a magnetic sensor 28. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rolling bearing unit with a magnetic encoder provided with a magnetic encoder used for detecting the rotational speed of a rotating body, and a method for manufacturing the same.

  Conventionally, anti-skid to prevent car skid (a phenomenon in which the wheel slips in a substantially stopped state) or traction control to effectively transmit the driving force to the road surface (unnecessary idling of the driving wheel that is likely to occur at the time of start and acceleration) The following structure is known as a rotational speed detection device used for control). That is, the rotational speed detection device is composed of an encoder that generates a pulse by magnetism and a detection sensor that senses the magnetic pulse of the encoder. As a general structure, the encoder is installed in a seal device that seals a bearing. The most commonly used one is a seal with a rotation speed detection device that is arranged side by side and in which a sealing means and a rotation speed detection means are integrated (see, for example, Patent Document 1).

  As shown in FIG. 12, the rotational speed detection device with a seal described in Patent Document 1 is attached to a seal member 102 attached to the outer ring 100, a slinger 103 fitted to the inner ring 101, and an outer surface of the slinger 103. The encoder 104 is made of a magnetic material that generates a magnetic pulse, and the rotation speed detection sensor 105 is disposed in the vicinity of the encoder 104 so as to detect the magnetic pulse from the encoder 104. Here, the bearing is prevented from leaking internal grease and entering water or foreign matter from the outside by the rotation detection device with a seal.

  The encoder 104 is made of an elastic magnetic material obtained by mixing magnetic powder into an elastic material such as rubber or resin, and is press-molded on the flange portion 103a of the slinger 103 to which an adhesive is applied in a mold. It is joined. Nitrile rubber containing ferrite is generally used as an encoder for an encoder, and the magnetic powder is mechanically oriented by kneading with a roll.

Further, in the configuration in which the magnet unit 104 is exposed to the outside, foreign objects such as stones are caught between the magnet unit 104 and the rotation speed detection sensor 105 due to rough road traveling or the like, and the magnet unit 104 is worn or cracked. Damage may occur. For this reason, it has been conventionally proposed to provide a protective plate so as to cover the magnet portion (see, for example, Patent Documents 2 and 3).
JP 2001-255337 A JP 2002-333033 A JP 2003-240007 A

  By the way, the magnet part of the magnetic encoder described in Patent Documents 2 and 3 is made of nitrile rubber containing ferrite, and in an encoder in which magnetic powder is mechanically oriented, a non-magnetic protective plate is interposed between them. There is a possibility that the magnetic characteristics are deteriorated and the detection accuracy such as the rotation speed is adversely affected.

  Therefore, the present invention has been made paying attention to such problems, and the purpose thereof is to maintain the detection accuracy of the rotational speed and the like even if a protective member is interposed, and to prevent damage and magnetic performance by the protective member. It is an object of the present invention to provide a rolling bearing unit with a magnetic encoder to which a compatible magnetic encoder is mounted and a method for manufacturing the same.

The above object of the present invention is achieved by the following configurations.
(1) A fixed wheel, a rotating wheel, a plurality of rolling elements arranged so as to be freely rollable in the circumferential direction between the fixed wheel and the rotating wheel, and a magnetic sensor fixed to the rotating wheel and for measuring the rotational speed A rolling bearing unit with a magnetic encoder comprising a magnetic encoder that generates a magnetic pulse detected by
The magnetic encoder includes a substantially annular magnet portion that is fixed to the rotating body so as to face the magnetic sensor for detecting the number of rotations, and is magnetized in multiple directions in the circumferential direction.
The magnet part is an anisotropic magnet made of a plastic magnet material using a thermoplastic resin containing magnetic powder as a binder.
A rolling bearing unit with a magnetic encoder, wherein a protective member made of a nonmagnetic material is provided so as to be interposed between a magnet portion and a magnetic sensor.
(2) The rolling bearing unit with a magnetic encoder according to (1), wherein the binder of the plastic magnet material is composed of at least a thermoplastic resin and an impact resistance improving material.
(3) The rolling bearing with a magnetic encoder according to (2), wherein the plastic magnet material further contains at least one amine-based antioxidant selected from diphenylamine-based compounds and p-phenylenediamine-based compounds. unit.
(4) The rolling bearing unit with a magnetic encoder according to any one of (1) to (3), wherein the protective member is fixed to one of a fixed wheel and a rotating wheel.
(5) The method of manufacturing a rolling bearing unit with a magnetic encoder according to any one of (1) to (4), wherein the magnetic encoder further includes a slinger made of a magnetic material,
A step of magnetic field injection molding of a plastic magnet material to become an anisotropic magnet;
Adhering and bonding the magnet part to the slinger with an adhesive that undergoes a curing reaction during injection molding;
A method for manufacturing a rolling bearing unit with a magnetic encoder, comprising:

  According to the rolling bearing unit with a magnetic encoder of the present invention, the magnet part is an anisotropic magnet made of a plastic magnet material using a thermoplastic resin containing magnetic powder as a binder, and the protective member made of a nonmagnetic material is the magnet part. Is provided so as to be interposed between the magnetic sensor and the magnetic sensor, so that the detection accuracy such as the rotation speed can be maintained even if a protective plate is interposed, and the magnetic encoder can achieve both prevention of damage by the protective plate and magnetic performance. .

  In addition, according to the method of manufacturing a rolling bearing unit with a magnetic encoder of the present invention, the magnetic part is formed by a magnetic field injection molding process of a plastic magnet material so as to become an anisotropic magnet, and an adhesive that undergoes a curing reaction during the injection molding. The magnet part becomes an anisotropic plastic magnet that can achieve high magnetic properties by magnetic field injection molding, and the slinger and magnet part can be joined at the time of injection molding. A highly reliable and reliable rolling bearing unit can be manufactured.

  Hereinafter, each embodiment of a rolling bearing unit with a magnetic encoder according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 shows a case where the present invention is applied to a hub unit bearing 2a for supporting a non-driving wheel, which is supported by an independent suspension, as a first embodiment of the present invention. Note that the configuration and operation other than the features of the present invention are the same as those of a conventionally well-known structure. Therefore, the description will be simplified, and the features of the present invention will be mainly described below.

  The hub unit bearing 2a includes an outer ring 5a that is a fixed ring, a hub 7a and an inner ring 16a that are rotating wheels (rotating bodies) that rotate integrally with a mounting flange 12 for fixing a wheel (not shown), an outer ring 5a, Balls 17a and 17a, which are a plurality of rolling elements, are arranged in an annular gap formed between the hub 7a and the inner ring 16 so as to be freely rollable in the circumferential direction and guided by the cage 18. A magnetic encoder 26 is fixed to the inner ring 16a, and generates a magnetic pulse detected by a magnetic sensor (rotational speed detection sensor) 28 for detecting the rotational speed.

  The inner ring 16a that is externally fitted to the small-diameter step portion 15 formed at the inner end portion of the hub 7a is restrained by a caulking portion 23 that is formed by caulking the inner end portion of the hub 7a radially outward. By attaching, it is fixedly coupled to the hub 7a. In addition, the wheel can be coupled and fixed freely by studs 8 that are implanted at predetermined intervals in the circumferential direction on mounting flanges 12 formed at the outer end portion of hub 7a and protruding from the outer end portion of outer ring 5a. Yes. On the other hand, the outer ring 5a can be coupled and fixed to a knuckle or the like (not shown) constituting a suspension device by a coupling flange 11 formed on the outer peripheral surface thereof.

  Further, seal rings 21a and 21b, which are sealing devices, are provided between the inner peripheral surfaces of both ends of the outer ring 5a, the outer peripheral surface of the intermediate portion of the hub 7a, and the outer peripheral surface of the inner end of the inner ring 16a. These seal rings 21a and 21b block the annular gap provided with the balls 17a and 17a and the external space between the inner peripheral surface of the outer ring 5a and the outer peripheral surfaces of the hub 7a and the inner ring 16a.

  Each of the seal rings 21a and 21b is formed by bending a mild steel plate and reinforcing the elastic members 22a and 22b with core bars 24a and 24b having an L-shaped cross section and an annular shape as a whole. Each of such seal rings 21a and 21b has a metal core 24a and 24b fitted into both ends of the outer ring 5a by an interference fit, and the tip ends of the seal lips formed by the respective elastic members 22a and 22b are connected to the hub. The slinger 25 is externally fitted and fixed to the outer peripheral surface of the intermediate portion 7a or the outer peripheral surface of the inner end portion of the inner ring 16a.

  As shown in FIG. 2, the magnetic encoder 26 includes a cylindrical portion 25a that can be externally fitted to the inner ring 16a, and an axial end portion of the cylindrical portion 25a that is continuously provided via a curved portion 25b and spreads outward in the radial direction. A slinger 25 having a flange portion 25c formed as described above, and an approximately circular shape that is attached to the outer surface of the flange portion 25c of the slinger 25 by an adhesive that undergoes a curing reaction during insert molding and is multipolarly magnetized in the circumferential direction. And a magnetic pole forming ring 27 which is an annular magnet portion. The magnetic pole forming ring 27 is fixed to the inner ring 16a via the slinger 25 so as to face the magnetic sensor 28 for detecting the rotational speed.

  As shown in FIG. 3, the magnetic pole forming ring 27 is a multipolar magnet, and N and S poles are alternately formed in the circumferential direction. The magnetic sensor 28 is arranged opposite to the outside of the magnetic pole forming ring 27 in the axial direction, and a protective cover 30 that is a protective member made of a nonmagnetic material is interposed between the magnetic pole forming ring 27 and the magnetic sensor 28. Further, the magnetic encoder 26 is fixed with an adhesive.

  In the present invention, the magnetic material of the magnetic pole forming ring 27 of the magnetic encoder 26 is not particularly limited, but considering the bonding property to the slinger 25 and the protective cover 30, the magnetic powder is contained in an amount of about 50 to 80% by volume, A plastic magnet compound using a plastic resin as a binder can be preferably used. As magnetic powder, ferrite such as strontium ferrite and barium ferrite, rare earth magnetic powder such as neodymium-iron-boron, samarium-cobalt, samarium-iron can be used, and lanthanum etc. to further improve the magnetic properties of ferrite The rare earth element may be mixed. When the content of the magnetic powder is less than 50% by volume, the magnetic properties are inferior, and it becomes difficult to perform multipolar magnetization in the circumferential direction at a fine pitch, which is not preferable. On the other hand, when the content of the magnetic powder exceeds 80% by volume, the amount of the binder is too small, the strength of the entire magnet is lowered, and at the same time, molding becomes difficult and practicality is lowered.

  When a thermoplastic resin is used as the binder, those that can be injection-molded are suitable. Specifically, a hard segment made of polyamide 6, polyamide 12, polyamide 612, polyamide 11, polyphenylene sulfide (PPS), polyamide 12 and A block copolymer consisting of a polyether segment or a soft segment consisting of a polyester chain, a hard segment consisting of a polyester such as modified polyamide 12, polybutylene terephthalate, polybutylene naphthalate, etc. and a soft segment consisting of a polyether chain or a polyester chain A modified polyester that is a block copolymer can be used. In addition, since there is a possibility that calcium chloride used as a snow melting agent in the encoder may be applied together with water, polyamide 12, polyamide 612, polyamide 11, polyphenylene sulfide (PPS), modified polyamide 12, and modified polyester with low water absorption are used. It is more preferable to use a resin binder.

  Furthermore, as a binder for preventing cracking due to a sudden temperature change (thermal shock) assumed in the use environment of the encoder, by adding it, a modified polyamide 12 that functions as a material for improving bending flexibility and crack resistance, Most preferred is polyester, a mixture of modified polyamide 12 and polyamide 12, or a mixture of modified polyester and polyester resin.

  As the impact resistance improving material, other vulcanized rubber ultrafine particles can be used. Specifically, it is selected from styrene butadiene rubber, acrylic rubber, acrylonitrile butadiene rubber, carboxyl modified acrylonitrile butadiene rubber, silicon rubber, chloroprene rubber, hydrogenated nitrile rubber, carboxyl modified hydrogenated nitrile rubber, and carboxyl modified styrene butadiene rubber. At least one kind of fine fine particles falling within the range of 30 to 300 nm in average particle diameter. When the average particle size is less than 30 nm, the production cost is high, and the fine particle size is too small and is not preferable. When the average particle size exceeds 300 nm, it is not preferable because the dispersibility is lowered and it is difficult to improve the impact resistance uniformly.

  Among the ultrafine particles of vulcanized rubber described above, acrylonitrile butadiene rubber (nitrile rubber), carboxyl-modified acrylonitrile butadiene rubber, acrylic rubber, silicone rubber, hydrogenated nitrile are considered in consideration of deterioration during pellet manufacturing and actual magnet molding. Rubber, carboxyl-modified hydrogenated nitrile rubber is preferred, and among them, those having an organic functional group such as a carboxyl group or an ester group in the molecular structure have a relatively strong interaction with the resin binder and are further preferred. Specifically, carboxyl-modified acrylonitrile butadiene rubber, acrylic rubber, and carboxyl-modified hydrogenated nitrile rubber. These vulcanized rubber ultrafine particles prevent deterioration due to heat or oxygen, and diphenylamine-based anti-aging agents such as 4,4 ′-(α, α-dimethylbenzyl) diphenylamine, and 2-mercaptobenzimidazole and the like. It is good also as what contained a subaging prevention agent etc.

  In addition, as an additive for improving impact resistance, other ethylene propylene non-conjugated diene rubber (EPDM), maleic anhydride-modified ethylene propylene non-conjugated diene rubber (EPDM), ethylene / acrylate copolymer, ionomer, etc. can be used. . These compounds are in the form of pellets, which are fluidized and microdispersed in the binder when mixed with magnetic powder, thermoplastic resin and the like and pelletized with an extruder.

  Moreover, the addition amount of the impact resistance improving material composed of the above modified resin or vulcanized rubber ultrafine particles is 5 to 60% by weight, more preferably 10 to 40% by weight in the total amount of the binder combined with the thermoplastic resin. is there. When the addition amount is less than 5% by weight, the amount is too small, and the effect of improving the impact resistance is small, which is not preferable. When the addition amount exceeds 60% by weight, the impact resistance is improved, but since the tensile strength and the like are reduced due to a decrease in the resin component, the practicality is lowered.

  Furthermore, in order to prevent deterioration due to heat of the thermoplastic resin and impact improver (modified resin or vulcanized rubber ultrafine particles, etc.) that are binders, in addition to those originally added to the material, an antioxidant effect Addition of a high amine antioxidant is more preferable because it can prevent deterioration due to heat. Examples of amine-based antioxidants used include diphenylamine compounds such as 4,4 ′-(α, α-dimethylbenzyl) diphenylamine and 4,4′-dioctyldiphenylamine, and N, N′-diphenyl-p-phenylenediamine. N-isopropyl-N′-phenyl-p-phenylenediamine, N, N′-di-2-naphthyl-p-phenylenediamine, N, N′-bis (1-methylheptyl) -p-phenylenediamine, N , N′-bis (1,4-dimethylpentyl) -p-phenylenediamine, N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, and the like are preferred. is there.

  The addition amount of the amine-based antioxidant is about 0.5 to 2.0% by weight based on the total weight of the binder weight and the antioxidant weight including the thermoplastic resin and the impact resistance improving material. is there. When the addition amount of the amine antioxidant is less than 0.5% by weight, the effect of improving the antioxidant is not sufficient, which is not preferable. In addition, when the added amount of the antioxidant exceeds 2.0% by weight, the effect of the antioxidant is not changed so much, and the amount of magnetic powder and binder is reduced correspondingly, so that the magnetic properties and mechanical strength are lowered. It is not preferable because it may cause a bloom on the surface of the molded product depending on the case, and this may adversely affect the adhesion with the slinger.

  In addition, as a magnetic powder, the ferrite type is most suitable in consideration of cost and oxidation resistance, but when rare earths are used in preference to magnetic properties, the oxidation resistance is lower than the ferrite type. In order to maintain stable magnetic characteristics over a long period of time, a surface treatment layer may be further provided on the exposed magnet surface. As the surface treatment layer, an electric or electroless nickel plating, an epoxy resin coating film, a silicon resin coating film, a fluororesin coating film, or the like can be specifically used.

  As the material of the slinger 25, ferritic stainless steel (SUS430, etc.), martensitic stainless steel (SUS410, etc.) that does not deteriorate the magnetic properties of the magnet material and has a certain level or more of corrosion resistance depending on the usage environment. In addition, magnetic materials such as high corrosion resistance ferritic stainless steels such as SUS434 and SUS444 in which Mo is further added to improve corrosion resistance are preferable.

  The material of the protective cover 30 may be any non-magnetic material that does not interfere with the detection of the rotational speed of the magnetic encoder 26 of the magnetic sensor 28. In consideration of impact strength and the like, non-magnetic metal, fiber reinforced plastic, and the like are suitable. is there. In the case of a non-magnetic metal, austenitic stainless steel such as SUS304, SUS316, etc. having corrosion resistance like the slinger 25 is most preferable. In the case of fiber reinforced plastic, if it is thermoplastic, if it is integrated with a plastic magnet by molding, sufficient attention must be paid to the melting point of the base resin used. The base resin is a thermoplastic resin such as polyamide 612, polyamide 610, polyamide MXD6, modified polyamide 6T, polybutylene terephthalate having a melting point of 200 ° C. or higher in consideration of adhesiveness, water resistance (snow melting agent resistance), and heat resistance. In addition, thermosetting resins such as epoxy resins and phenol resins can be suitably used. Glass fiber, aramid fiber, and carbon fiber are compounded and reinforced by adding 20 to 60% by weight to these base resins to improve mechanical strength.

  Further, the protective cover 30 only needs to have a flange 30a that covers the upper surface 27a that is the detection surface side portion of the magnetic pole forming ring 27, but as shown in FIG. And by having the annular cylinder part 30b which covers the outer peripheral surface of the flange part 25c of the slinger 25, the infiltration of water from the adhesion surface of the slinger 25 and the magnetic pole forming ring 27 can be prevented.

  The magnet bonding surface of the slinger 25 used in the present invention is preferably provided with fine irregularities in order to improve the bonding force with the adhesive. As a method for providing the irregularities, a shot blasting process or press molding is used. In addition to a mechanical method such as a method using uneven transfer on the mold surface, the surface once surface-treated may be chemically etched with an acid or the like. Providing irregularities on the magnet bonding surface is more preferable because an adhesive enters the magnetic bonding surface and the bonding force between the magnetic pole forming ring 27 and the slinger 25 is strengthened by the anchor effect. Further, when the protective cover 30 made of a nonmagnetic metal and the plastic magnet are integrated by molding, it is more preferable that the above-described unevenness is provided also on the magnet bonding surface of the protective cover 30.

  The adhesive used in the magnetic encoder of the present embodiment is in a semi-cured state to such an extent that it is not detached and washed away by a molten high-pressure plastic magnet material or rubber magnet material during insert molding. -Completely cured by heat from fluid rubber or in addition to secondary heating after molding. Adhesives that can be used can be diluted with a solvent, and phenol resin adhesives, epoxy resin adhesives, etc., which proceed with a curing reaction close to two stages, take into account heat resistance, chemical resistance, and handling properties. It is preferable.

  When the magnet material is a plastic magnet using a thermoplastic plastic as a binder, the molding of the encoder part is such that the plastic magnet material melted from the inner diameter thickness part simultaneously flows into the mold at a high pressure and is rapidly cooled and solidified in the mold. A disk gate type or similar ring gate type injection molding is preferred. In either gate system, the molten resin spreads in a disk shape and then flows into the mold corresponding to the inner diameter thick portion, so that the flake-like magnetic powder contained therein is oriented parallel to the surface. In particular, the portion between the inner diameter portion and the outer diameter portion detected by the rotation sensor in the vicinity of the inner diameter thick portion has a higher orientation and is very close to the axial anisotropy oriented in the thickness direction. Yes. If a magnetic field is applied to the mold in the thickness direction at the time of molding, the anisotropy becomes closer to perfection. Even when magnetic field molding is performed, if the gate is a disk gate other than a ring gate, for example, a pin gate, the orientation at the weld is completely different in the process of gradually increasing the resin viscosity toward solidification. It is difficult to form a crystallized structure, and it is not preferable because it may cause cracks or the like due to long-term use in the weld portion in which the magnetic properties are lowered and the mechanical strength is lowered.

  For example, when the magnet material is a plastic magnet, a thermosetting adhesive containing at least one of a group of a phenol resin and an epoxy resin is semi-cured on the surface of the roughened slinger 25 and the protective cover 30. The magnetic material injection molding machine 80 performs injection molding (insert molding) of the plastic magnet material using the slinger 25 and the protective cover 30 coated with the adhesive as a core.

  As shown in FIG. 4, the magnetic field injection molding machine 80 includes a mold clamping device 82 and an injection device 83 on a support base 81. The mold clamping device 82 includes a movable part 86 that is movable with respect to a housing 85 that is fixed to the support base 81 by a movable mechanism 84 such as a toggle mechanism, a fixed part 87 that is fixed to the support base 81, and a movable part 86. Are provided between the housing 85 and the fixed portion 87 and four tie bars 88. The movable part 86 and the fixed part 87 include a movable mold 89 and a fixed mold 90, respectively. In addition, coils 91 and 92 are arranged on the side surfaces of the movable portion 86 and the fixed portion 87 and are energized by the power supply device 93. The control device 94 is connected to the movable mechanism 84, the power supply device 91, and the injection device 83, and is configured to control them.

  As shown in FIG. 5A, the movable side mold 89 is composed of a plurality of movable side mold pieces 89a to 89c that are bolted to the contact plate 95, and the fixed side mold 90 is also a plurality of fixed sides. It consists of mold pieces 90a to 90c. A cavity 96 and a disk gate 97 are formed between the opposed surfaces of the movable mold 89 and the fixed mold 90. Thereby, the melted plastic magnet material injected from the nozzle 98 of the injection device 83 is filled into the cavity 96 from the sprue portion 99 through the disk gate 97. As shown in FIG. 5B, an annular space for accommodating the cylindrical portion 25a of the slinger 25 is formed between the movable mold pieces 89a and 89b, and the fixed mold piece 90a located at the center. Protrudes toward the movable mold 89 from the fixed mold piece 90b located on the outer diameter side, and the fixed mold piece 90a is positioned so as to overlap with the accommodated slinger 25 in the radial direction. . A protective cover 30 is held in the cavity 96, and the inner peripheral surface of the annular cylindrical portion 30 b for covering the outer peripheral surface of the magnetic pole forming ring 27 is brought into contact with the outer peripheral surface of the flange portion 25 c of the slinger 25. At the same time, the flange 30a to be joined to the upper surface of the magnetic pole forming ring 27 is set on the surface of the fixed-side mold piece 90b.

  In addition, when the plastic magnet material melted in the molds 89 and 90 attached to the magnetic field injection molding machine 80 is injected, a coil current is applied to the coils 91 and 92 at both ends of the molds 89 and 90 to obtain a thickness. The plastic magnet material is magnetized by a magnetic field generated in one direction (with the same polarity) to orient the magnetic powder. After that, demagnetization that demagnetizes with a magnetic field in the opposite direction to the magnetization direction during cooling in the molds 89 and 90, and an initial coil current that is higher than the coil current at the time of magnetization, the polarity is alternately reversed and the amplitude gradually increases. The demagnetization is performed by at least one step of reversal demagnetization in which a plurality of pulse currents that become smaller are applied to the coils 91 and 92 at both ends of the mold to demagnetize. Next, after removing the gate portion, the adhesive is completely cured by heating at a constant temperature and a constant time in a thermostatic bath or the like, and the magnetic pole forming ring 27, the slinger 25, and the protective cover 30 are firmly bonded. In some cases, it may be completely cured by heating at a high temperature for a short time, such as by high-frequency heating. Thereafter, it is further demagnetized to a magnetic flux density of 2 mT or less, more preferably 1 mT or less, using a known oil condenser type demagnetizer. In a subsequent process, multipole magnetization is performed by superimposing it on a known magnetizing yoke.

  The number of poles of the magnetic pole forming ring 27 formed in this way is about 70 to 130, preferably 90 to 120. If the number of poles is less than 70, the number of poles is too small and it is difficult to accurately detect the rotational speed. On the other hand, when the number of poles exceeds 130, each pitch becomes too small, and it is difficult to suppress a single pitch error, and the practicality is low.

  Therefore, according to the rolling bearing unit with a magnetic encoder of the present embodiment, the magnetic pole forming ring 27 is an anisotropic magnet made of a plastic magnet material using a thermoplastic resin containing magnetic powder as a binder, and made of a non-magnetic material. A protective cover 30 is provided so as to be interposed between the magnetic pole forming ring 27 and the magnetic sensor 28. As a result, the magnetic pole forming ring 27 becomes an anisotropic plastic magnet that can achieve high magnetic characteristics by magnetic field orientation. Even if the nonmagnetic protective cover 30 for preventing foreign matter damage is disposed on the detection surface side portion of the magnetic pole forming ring 27. The magnetic flux density for detecting the number of rotations can be maintained at a certain level or more, the detection accuracy is not reduced, and a highly reliable rolling bearing unit in which damage prevention by the protective cover 30 and improvement of magnetic performance are both achieved. .

  In addition, according to the method for manufacturing a rolling bearing unit with a magnetic encoder of this embodiment, magnetic pole formation is performed by a step of magnetic field injection molding of a plastic magnet material to become an anisotropic magnet, and an adhesive that undergoes a curing reaction at the time of injection molding. And the step of bonding the ring 27 to the slinger 25, the magnetic pole forming ring 27 becomes an anisotropic plastic magnet that can achieve high magnetic properties by magnetic field injection molding, and the slinger 27 and the magnetic pole forming ring at the time of injection molding. 27 can be joined, and a rolling bearing unit with high productivity and reliability can be manufactured.

(Second Embodiment)
Next, a rolling bearing unit with a magnetic encoder according to a second embodiment of the present invention will be described in detail.

  As shown in FIG. 6, the rolling bearing unit with magnetic encoder 40 of the present embodiment is formed between an outer ring 41 that is a fixed ring, an inner ring 42 that is a rotating ring (rotating body), and an outer ring 41 and an inner ring 42. A rolling bearing comprising a plurality of balls 43 that are a plurality of rolling elements that are arranged in a circumferential direction by the annular gap and are held at equal intervals in the circumferential direction by a cage 44; A sealing device 45 disposed at the end, a magnetic encoder 46, a sensor 47, and a protective plate 48 as a protective member are provided.

  The sealing device 45 includes a seal member 50 mounted on the inner peripheral surface of the outer ring 41, and a slinger 60 disposed on the bearing outer side than the seal member 50 and fixed to the outer peripheral surface of the inner ring 42. The sealing member 50 and the slinger 60 close the opening end of the annular gap to prevent foreign matters such as dust from entering the bearing and prevent the lubricant filled in the bearing from leaking. . As in the first embodiment, the slinger 60 is formed so as to extend outward in the radial direction by being connected to the cylindrical portion 60a that is fitted to the inner ring 42 and the curved end portion 60b at the axial end of the cylindrical portion 60a. It has the flange-shaped flange part 60c made. The magnetic encoder 46 includes a slinger 60 and a magnetic pole forming ring 61 which is a magnet portion attached to the slinger 60. The magnetic pole forming ring 61 is fixed to the inner ring 42 with the slinger 60 as a fixing member. Yes.

  The seal member 50 is configured by reinforcing an elastic member 52 formed in an annular shape having a substantially L-shaped cross section with a core metal 51 formed in an annular shape having a substantially L-shaped cross section. It is installed. The distal end portion of the elastic member 52 is branched into a plurality of sliding contact portions. Are in sliding contact with each other. Thereby, a high sealing force is obtained.

  Further, the protection plate 48 is detected by the annular cylindrical portion 48a press-fitted and fixed to a stepped portion 42a provided on the outer peripheral surface of the shoulder portion of the inner ring 42, and the magnetic pole forming ring 61 extending radially outward from the annular cylindrical portion 48a. It has the collar part 48b which opposes a surface side part. The protective plate 48 is formed by fitting the cylindrical portion 60a of the slinger 60 to the outer peripheral surface of the shoulder portion of the inner ring 42 and then press-fitting the annular cylindrical portion 48a into the stepped portion 42a. It is attached to the inner ring 42 with a slight gap or contact with the detection surface side portion. Thereby, the protection plate 48 made of a nonmagnetic material is provided so as to be interposed between the magnetic pole forming ring 61 and the magnetic sensor 47.

  In the case where a gap is provided between the protective plate 48 and the magnetic pole forming ring 61, the gap is 0.5 mm or less, more preferably 0.1 mm or less, in order to prevent foreign matters such as sand from entering the gap. If the gap exceeds 0.5 mm, foreign matter can easily enter, and the air gap with the rotation sensor must be increased.

  In this embodiment, since the protection plate 48 is separate from the magnetic encoder 46, the molding method of the magnetic encoder 46 is different from that of the first embodiment only in that it is formed separately from the protection plate 48. The forming ring 61 is bonded and bonded to the slinger 60 by an adhesive in which a plastic magnet material containing a thermoplastic resin containing magnetic powder as a binder is made anisotropic by magnetic field injection molding and a curing reaction proceeds during insert molding. Further, the composition of the magnetic encoder 46, the material of the protective plate 48, and the like are the same as those in the first embodiment.

  Therefore, according to the rolling bearing unit with a magnetic encoder of this embodiment, the magnetic pole forming ring 61 becomes an anisotropic plastic magnet that can achieve high magnetic characteristics by magnetic field orientation, and foreign matter breakage occurs in the detection surface side portion of the magnetic pole forming ring 61. Even if the non-magnetic protective cover 48 for prevention is arranged, the magnetic flux density for detecting the rotational speed can be maintained at a certain level or more, and the detection accuracy is not reduced, and both the damage prevention by the protective plate 48 and the improvement of the magnetic performance are achieved. This is a reliable rolling bearing unit with a high reliability.

  The configuration of the rolling bearing unit with a magnetic encoder according to the present embodiment is also applicable to a hub unit bearing as shown in FIG. 1, and as shown in FIG. 7, a protection plate 48 is provided on the inner ring 16a. It can be press-fitted and fixed to the stepped portion 16 b and can be arranged in contact with the detection surface side portion of the magnetic pole forming ring 61.

(Third embodiment)
Next, a rolling bearing unit with a magnetic encoder according to a third embodiment of the present invention will be described in detail.

  As shown in FIG. 8, the rolling bearing unit with magnetic encoder 40A of this embodiment is different from that of the second embodiment in that a protection plate 70 as a protection member is attached to an outer ring 41 as a stationary wheel.

  That is, the protective plate 70 is detected by the annular cylindrical portion 70a that is press-fitted and fixed to the stepped portion 41a provided on the inner peripheral surface of the shoulder of the outer ring 41, and the magnetic pole forming ring 61 that extends radially inward from the annular cylindrical portion 70a It has the collar part 70b facing a surface side part. The protective plate 70 is formed by fitting the seal member 50 to the inner peripheral surface of the shoulder portion of the outer ring 41 and the cylindrical portion 60a of the slinger 60 to the outer peripheral surface of the shoulder portion of the inner ring 42, and then changing the annular cylindrical portion 70a to the step portion 41a. The flange 70b is attached to the outer ring 41 with a slight gap from the detection surface side portion of the magnetic pole forming ring 61. Thus, the protective plate 70 made of a nonmagnetic material is provided so as to be interposed between the magnetic pole forming ring 61 and the magnetic sensor 47.

The gap between the protective plate 70 and the magnetic pole forming ring 61 is set in the range of 0.1 mm to 0.5 mm. If the clearance is less than 0.1, thermal expansion caused by rotation of the bearing may cause contact with the magnetic pole forming ring 61 of the magnetic encoder 46, which may hinder the rotation of the bearing and detection of the number of rotations. . On the other hand, if the gap exceeds 0.5 mm, foreign matter can easily enter, and the air gap with the magnetic sensor 47 must be increased. The magnetic sensor 47 is preferably brought into contact with the flange portion 70b in order to reduce the air gap with the protective plate 70.
Other configurations and operations are the same as those of the second embodiment.

  In this embodiment, the protective plate 70 is press-fitted and fixed to the stepped portion 41a formed on the inner peripheral surface of the shoulder of the outer ring 41. However, like the rolling bearing unit with magnetic encoder 40B shown in FIG. The annular cylindrical portion 71a is press-fitted and fixed to the step portion 41b formed on the outer peripheral surface of the outer ring 41, and the flange portion 71b is attached to the outer ring 41 with a slight clearance from the detection surface side portion of the magnetic pole forming ring 61. You may do it.

  Further, the configuration of the rolling bearing unit with a magnetic encoder of the present embodiment can also be applied to a hub unit bearing as shown in FIG. 1 and, as shown in FIG. Further, a protective cover 73 as a protective member fixed to the inner peripheral surface of the outer ring 5a is formed so as to block the one end opening in the axial direction of the outer ring 5a along the shape of the caulking portion 23 of the inner ring 16a and the hub ring 7a. May be. In this hub unit bearing, since the protective cover 73 covers one axial end of the annular space between the outer ring 5a and the inner ring 16a, there is no need to provide the seal ring 21b. The protective cover 73 is fitted and fixed to the inner peripheral surface of the shaft end of the outer ring 5a, but may be fixed to the outer peripheral surface of the shaft end.

(Fourth embodiment)
Next, a rolling bearing unit with a magnetic encoder according to a fourth embodiment of the present invention will be described in detail.

  As shown in FIG. 11, the rolling bearing unit with magnetic encoder 40 </ b> C of this embodiment is different from that of the third embodiment in that a protective plate 70 that is a protective member has a seal lip 72.

That is, the protective plate 70 has a rubber seal lip 72 that is in sliding contact with the outer peripheral surface of the shoulder portion of the inner ring 42 at the inner peripheral end portion of the flange portion 70b. Thereby, since the protective plate 70 constitutes a seal structure that prevents the entry of foreign matter from the outside, the reliability of the rolling bearing unit 40C can be further improved.
Other configurations and operations are the same as those of the third embodiment.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.

  Here, although an Example is given and this invention is demonstrated further, this invention is not restrict | limited at all by this.

  As a magnet material for forming test, an anisotropic plastic magnet compound containing strontium ferrite composed of the following constituent materials was used.

-Anisotropic strontium ferrite for magnetic field orientation 89.5wt%
(FERO TOP FM-201, manufactured by Toda Industries)
・ PA12 7.0wt%
(PA12 powder P3012U, containing hindered phenol antioxidant; manufactured by Ube Industries)
・ Modified PA12 3.0wt%
(UBEPAE1210U, containing hindered phenolic antioxidant; manufactured by Ube Industries)
・ Silane coupling agent 0.3wt%
(Γ-aminopropyltriethoxysilane, A-1100; manufactured by Nihon Unicar)
・ Amine antioxidant 0.2wt%
(N, N′-diphenyl-p-phenylenediamine, Nocrack DP, manufactured by Ouchi Shinsei Chemical Industry)

  In addition, as a slinger, no. A SUS430 having a thickness of 0.6 mm and subjected to 2B finishing (about Ra 0.06) was used as a base material. Then, irregularities were provided only in the magnet joint (about 0.8 in Ra) by shot blasting. The seal sliding surface side is untreated.

  As an adhesive, a 30% solids phenol resin adhesive (Metal Lock N-15, manufactured by Toyo Chemical Research Laboratories) consisting mainly of a novolak-type phenol resin is further diluted 3 times with methyl ethyl ketone, and the surface of the slinger is obtained by dipping treatment. It was applied to. Then, after drying at room temperature for 30 minutes, it was made into the semi-hardened state by leaving it to stand in 120 degreeC for 30 minutes.

  As a protective cover, no. A SUS304 having a thickness of 0.3 mm and subjected to 2B finishing (about Ra 0.06) was used as a base material. Irregularities were provided only at the magnet joint (about 0.8 in Ra) by shot blasting. The opposite side of the magnetic sensor is unprocessed.

The magnet part was molded with a disk gate by applying a magnetic field in the thickness direction at the time of molding, with the slinger and protective member coated with adhesive as the core. Thereafter, reversal demagnetization was performed when the mold was cooled, and the magnet was completely demagnetized, and then magnetized with NS in 96 poles together with the magnetized yoke. By performing magnetic field shaping in this way, the maximum energy product was set to 1.9 MGOe (14.8 kJ / m ³ ). Further, in order to completely cure the adhesive, it was heated at 150 ° C. for 1 hour. The thickness of the magnet part to be molded was 0.9 mm.

  According to the rolling bearing unit with a magnetic encoder of the embodiment configured as described above, the magnet portion is an anisotropic magnet made of a plastic magnet material using a thermoplastic resin containing magnetic powder as a binder, and is a non-magnetic material. A protective member made of is provided so as to be interposed between the magnet portion and the magnetic sensor. As a result, the magnet part becomes an anisotropic plastic magnet that can achieve high magnetic properties by magnetic field orientation, and the rotational speed is detected even if a nonmagnetic protective member for preventing foreign object damage is placed on the detection surface side part of the magnet part. Thus, a highly reliable rolling bearing unit that can maintain a magnetic flux density at a certain level or higher, does not reduce detection accuracy, and achieves both prevention of damage by the protective member and improvement of magnetic performance.

It is sectional drawing which shows the rolling bearing unit with a magnetic encoder which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the sealing device provided with the magnetic encoder of 1st Embodiment. It is a perspective view which shows the example by which the multipolar magnetization was carried out in the circumferential direction of the magnetic pole formation ring. It is a schematic diagram which shows a magnetic field injection molding machine. It is sectional drawing of the movable side metal mold | die and fixed side metal mold | die which form a cavity. It is sectional drawing which shows the rolling bearing unit with a magnetic encoder which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the rolling bearing unit with a magnetic encoder which concerns on the modification of 2nd Embodiment of this invention. It is sectional drawing which shows the rolling bearing unit with a magnetic encoder which concerns on 3rd Embodiment of this invention. It is sectional drawing which shows the rolling bearing unit with a magnetic encoder which concerns on the modification of 3rd Embodiment of this invention. It is sectional drawing of the rolling bearing unit with a magnetic encoder which concerns on the other modification of 3rd Embodiment of this invention. It is sectional drawing which shows the rolling bearing unit with a magnetic encoder which concerns on 4th Embodiment of this invention. It is sectional drawing which shows the conventional rolling bearing unit.

Explanation of symbols

2a Rolling bearing unit for wheel support (rolling bearing unit with magnetic encoder)
5a Outer ring 7a Hub 8 Stud 11 Coupling flange 12 Mounting flange 15 Small diameter step portion 16a Inner ring 18 Retainer 21a, 21b Seal ring 22a, 22b Elastic material 23 Caulking portion 24b Core metal 25 Slinger 26 Magnetic encoder 27 Magnetic pole forming ring (magnet portion)
30 Protective cover (protective member)

Claims (5)

A magnet comprising: a fixed wheel; a rotating wheel; a plurality of rolling elements arranged to be rotatable in a circumferential direction between the fixed wheel and the rotating wheel; and a magnetic encoder fixed to the rotating wheel. A rolling bearing unit with an encoder,
The magnetic encoder includes a substantially annular magnet portion that is fixed to a rotating body so as to face a magnetic sensor for detecting the number of rotations and is magnetized in multiple directions in the circumferential direction.
The magnet part is an anisotropic magnet made of a plastic magnet material using a thermoplastic resin containing magnetic powder as a binder,
A rolling bearing unit with a magnetic encoder, wherein a protective member made of a nonmagnetic material is provided so as to be interposed between the magnet portion and the magnetic sensor.   The rolling bearing unit with a magnetic encoder according to claim 1, wherein the binder of the plastic magnet material includes at least a thermoplastic resin and an impact resistance improving material.   The rolling bearing unit with a magnetic encoder according to claim 2, wherein the plastic magnet material further contains at least one amine-based antioxidant selected from a diphenylamine-based compound and a p-phenylenediamine-based compound.   The rolling bearing unit with a magnetic encoder according to claim 1, wherein the protective member is fixed to either one of a fixed wheel and a rotating wheel. The method of manufacturing a rolling bearing unit with a magnetic encoder according to any one of claims 1 to 4, wherein the magnetic encoder further comprises a slinger made of a magnetic material.
Magnetic field injection molding the plastic magnet material to become the anisotropic magnet;
A step of adhesively bonding the magnet part to the slinger with an adhesive that undergoes a curing reaction during the injection molding;
A method of manufacturing a rolling bearing unit with a magnetic encoder, comprising:

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