JP2008199035A - Magnetic encoder and rolling bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encoder having a high magnetic characteristic, capable of detecting the rotational frequency with high accuracy, and is less likely to generate cracks, or the like, even in a severe usage conditions, and to provide a rolling bearing unit. <P>SOLUTION: The magnetic encoder is equipped with a fixing member 25 mountable on a rotator, and a substantially annular magnet part 26, mounted on the fixing member 25 and magnetized in multiple poles in the circumferential direction. The magnet part 26 comprises a plastic magnet material, by using a thermoplastic resin including 86-92 wt.% of a magnetic substance powder as a binder. The magnet part 26 is chemically bonded to the fixing member 25 comprising a magnetic material by an adhesive, wherein a hardening reaction proceeds at the insert molding time. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  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) As a rotation speed detection device used for control, etc., there are an annular encoder in which N poles and S poles are alternately magnetized in the circumferential direction, and a sensor for detecting a change in the magnetic field in the vicinity of the encoder. It is also known that an encoder is provided alongside a sealing device for sealing a bearing that supports a wheel so that the encoder rotates together with the rotation of the wheel, and a magnetic field change synchronized with the rotation of the wheel is detected by a sensor. (For example, refer to Patent Documents 1 and 2.)

  As shown in FIG. 10, the rotational speed detector with a seal described in Patent Document 1 is attached to a seal member 102 attached to the outer ring 101 a, a slinger 103 fitted to the inner ring 101 b, and an outer surface of the slinger 103. The encoder 104 is configured to generate a magnetic pulse, and the sensor 105 is disposed adjacent to the encoder 104 to detect the magnetic pulse. In the bearing unit to which this rotational speed detector with a seal is attached, the sealing member 102 and the slinger 103 prevent foreign matters such as dust and water from entering the inside of the bearing, so that the lubricant filled in the bearing can be prevented. Prevents leakage outside the bearing. The encoder 104 generates the number of magnetic pulses corresponding to the number of poles during one rotation of the inner ring 101b, and detects the number of rotations of the inner ring 101b by detecting this magnetic pulse with the sensor 105.

Conventionally, an elastic magnetic material obtained by mixing magnetic powder into an elastic material such as rubber or resin is used for a magnetic encoder used for a wheel bearing. The magnetic encoder made of magnetic rubber is suitably bonded to the slinger by vulcanization adhesion, so it absorbs the thermal expansion / contraction difference with the slinger under severe temperature environment (-40 ° C to 120 ° C) by its elastic deformation. can do. For this reason, even in such a temperature environment, the sticking property to the slinger is maintained, and the problem of peeling hardly occurs. Generally, a nitrile rubber containing ferrite is used as a magnetic powder for an encoder, and the magnetic powder is mechanically oriented by being kneaded with a roll. .
JP 2001-255337 A JP 2003-57070 A

  In recent years, in order to more accurately detect the rotation speed of the wheel, the magnet portion of the magnetic encoder tends to be further multipolar in the circumferential direction. However, in the conventional ferrite magnet rubber-encoder based on the mechanical orientation method, the magnetic flux density per pole is reduced, and the gap between the sensor and the magnet (ie, the air gap) is reduced in order to detect the rotational speed with high accuracy. As a result, assembly may be difficult. For this reason, in order to make an air gap large from the surface of assembling property, it is necessary to improve the magnetic characteristic of a magnet.

  However, when the mixing amount of the magnetic powder is increased in order to improve the magnetic characteristics of the rubber magnet, the elasticity is lowered with the decrease in strength, so that excellent thermal shock resistance is remarkably impaired. For this reason, since the absorption effect of the thermal expansion difference between the rubber magnet and the slinger is impaired, the rubber magnet may be peeled off from the slinger, or the rubber magnet may be cracked or cracked.

  On the other hand, a plastic magnet in which magnetic powder is mixed with plastic can mix a relatively large amount of magnetic powder with a rubber magnet. In this respect, it becomes an encoder material having a magnetic property superior to that of a rubber magnet. With the possibility to get. Furthermore, the plastic magnet is easy to be injection-molded (magnetic field molding) in a state where a magnetic field is applied, whereby an anisotropic magnet indispensable for exhibiting excellent magnetic properties can be obtained.

  However, since plastic magnets cannot be fixed to slinger by vulcanization bonding method like rubber magnets, they are usually simply joined by an adhesive or the like, or formed integrally by insert molding method. However, depending on the type of plastic as a binder, any method may not be able to obtain a large adhesive strength equivalent to that of vulcanization adhesion. In such a case, under severe use conditions, the worst case may occur.

  Also, plastic magnets usually do not have the same flexibility as rubber magnets, so there is almost no absorption of thermal expansion differences during sudden temperature changes, just like rubber magnets with an increased amount of magnetic powder. , May cause peeling and cracking problems.

  The present invention has been made in order to solve the above-described problems, and its purpose is to prevent the magnet portion from cracking or falling off the slinger, which is a fixed member, even under severe use conditions. Another object of the present invention is to provide a highly reliable encoder that has high magnetic characteristics and enables highly accurate rotation speed detection, a manufacturing method thereof, and a rolling bearing unit.

The above object of the present invention can be achieved by the following constitution.
(1) A magnetic encoder comprising: a fixing member that can be attached to a rotating body; and a substantially annular magnet portion that is attached to the fixing member and is multipolarly magnetized in the circumferential direction,
The magnet part is made of a plastic magnet material containing a thermoplastic resin containing 86 to 92% by weight of magnetic powder as a binder,
The magnetic encoder, wherein the magnet portion is chemically joined to the fixing member made of a magnetic material by an adhesive that undergoes a curing reaction during insert molding.
(2) A magnetic encoder comprising: a fixing member that can be attached to a rotating body; and a substantially annular magnet portion that is attached to the fixing member and is multipolarly magnetized in the circumferential direction,
The magnet part is made of a magnet material containing a ferrite magnetic powder and a thermoplastic resin,
The magnet portion is integrally joined to the fixing member made of a magnetic material,
The magnetic part has a thickness of 3.0 mm and a bending deflection at 23 ° C. in the range of 2 to 10 mm.
(3) The magnetic encoder according to (1) or (2), wherein the fixing member is made of a roughened iron-based magnetic material accompanied by a chemical etching process.
(4) The thermoplastic resin is composed of a mixture including a polyamide-based thermoplastic elastomer having polyamide as a hard segment and at least one selected from the group consisting of polyamide 12, polyamide 11, and polyamide 612 (1) The magnetic encoder according to any one of (3) to (3).
(5) The thermoplastic resin includes a polyamide 12 thermoplastic elastomer, which is a block copolymer having a hard segment of polyamide 12 and a soft segment of a polyether component, according to (1) to (4), The magnetic encoder in any one.
(6) The magnetic encoder according to any one of (1) to (5), wherein the magnetic powder is at least strontium ferrite.
(7) The magnetic encoder according to (1), wherein the adhesive is at least one selected from the group of a phenol resin adhesive and an epoxy resin adhesive.
(8) The magnetic encoder according to any one of (1) to (7), wherein a maximum energy product BHmax as a magnet material of the magnet portion is in a range of 1.63 to 2.38 MGOe.
(9) A fixed wheel, a rotating wheel, a plurality of rolling elements disposed so as to be rotatable in a circumferential direction between the fixed wheel and the rotating wheel, and the rotating wheel (1) to A rolling bearing unit comprising the magnetic encoder according to any one of (8).
(10) A method of manufacturing a magnetic encoder comprising: a fixing member that can be attached to a rotating body; and a substantially annular magnet portion that is attached to the fixing member and is multipolarly magnetized in the circumferential direction.
Injecting a molten plastic magnet material into a mold attached to a magnetic field injection molding machine using the fixing member baked in a semi-cured state on the surface as a core,
In combination with the injection step, applying a coil current to the coils at both ends of the mold to magnetize the plastic magnet material with a generated unidirectional magnetic field;
When the plastic magnet material is cooled in the mold, the polarity reverses alternately, starting with demagnetization that demagnetizes with a magnetic field opposite to the magnetization direction, and an initial coil current higher than the coil current at the time of magnetization. And demagnetizing by at least one of reversal demagnetization to demagnetize by applying a plurality of pulse currents gradually decreasing in amplitude to the coil of the mold,
A method for manufacturing a magnetic encoder, comprising: demagnetizing to a magnetic flux density of 2 mT or less with a demagnetizer and then superimposing it on a magnetized yoke to perform multipolar magnetization.

  The encoder of the present invention, the manufacturing method thereof, and the rolling bearing unit prevent the magnet portion from cracking even under severe use conditions, or the magnet portion from falling off the slinger, which is a fixed member. High and highly reliable rotation speed detection is possible.

  Hereinafter, embodiments of an encoder and a rolling bearing unit of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 shows, as an example of an embodiment of the present invention, a case where the present invention is applied to a wheel support rolling bearing unit 2a for supporting a non-driving wheel supported by an independent suspension. 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 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. The hub 7a and the inner ring 16a constitute a rotating wheel (rotating body). Further, the wheel is formed by a stud 8 planted at a predetermined interval in the circumferential direction on a mounting flange 12 formed at a portion protruding from the outer end portion of the outer ring 5a which is a fixed wheel at the outer end portion of the hub 7a. It can be connected and fixed freely. 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. Between the outer ring 5a, the hub 7a and the inner ring 16a, balls 17a and 17a, which are a plurality of rolling elements guided by a cage 18, are arranged so as to be rotatable in the circumferential direction.

  Further, seal rings 21a and 21b are provided between the inner peripheral surfaces of both ends of the outer ring 5a, the outer peripheral surface of the intermediate part of the hub 7a, and the outer peripheral surface of the inner end part of the inner ring 16a, respectively. These seal rings 21a and 21b block the space provided with the balls 17a and 17a from the outer 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 slinger 25 that is a fixed member, and a magnetic pole forming ring 27 that is a magnet portion integrally joined to the side surface of the slinger 25. 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. Then, a magnetic sensor 28 is disposed facing the magnetic pole forming ring 27 (see FIG. 1).

  In the present invention, as the magnetic material of the magnetic pole forming ring 27 of the magnetic encoder 26, an anisotropic magnet compound containing 86 to 92% by weight of anisotropic magnetic powder and a thermoplastic resin as a binder is preferably used. Can be used. As the magnetic powder, ferrite such as strontium ferrite is most suitable in consideration of weather resistance. Further, in order to improve the magnetic properties of the ferrite, lanthanum and cobalt are mixed, or a part of the ferrite is neodymium-iron. -It may be replaced with rare earth magnetic powder such as boron, samarium-cobalt, samarium-iron. When the content of the magnetic powder is less than 86% by weight, the magnetic properties are equal to or less than those of conventionally used ferrite rubber magnets, and it is difficult to perform multipolar magnetization in the circumferential direction at a fine pitch. It is not preferable. On the other hand, when the content of the magnetic powder exceeds 92% by weight, the amount of the resin binder becomes too small, the strength of the whole magnet is lowered, and at the same time, molding becomes difficult and practicality is lowered.

  As a binder, in order to prevent cracks occurring in various environments such as temperature changes, a polyamide-based thermoplastic elastomer that is a block copolymer having a hard segment made of polyamide such as polyamide 12 and a soft segment of a polyether component is used. In order to maintain the balance between the tensile strength, heat resistance, and the like as the main constituent components, a mixture obtained by further mixing at least one ordinary polyamide selected from the group of polyamide 12, polyamide 11, and polyamide 612 may be used.

  Examples of the polyamide 12-based thermoplastic elastomer having the polyamide 12 as a hard segment include an aminocarboxylic acid compound represented by the formula (A1) and / or a lactam compound represented by the formula (A2), and a triblock polycrystal represented by the formula (B). Examples thereof include those obtained by polymerizing an etherdiamine compound and a dicarboxylic acid compound represented by the formula (C).

(However, R ¹ represents a linking group containing a hydrocarbon chain.)

(However, R ² represents a linking group containing a hydrocarbon chain.)

  (However, x represents a numerical value of 1 to 20, y represents a numerical value of 4 to 50, and z represents a numerical value of 1 to 20.)

(However, R ³ represents a linking group containing a hydrocarbon chain, and m is 0 or 1.)

  Here, the aminocarboxylic acid compound and / or the lactam compound is 10 to 95 mass based on the total amount of the compound of the formula (A1), the compound of the formula (A2), the compound of the formula (B), and the compound of the formula (C). It is preferably used in an amount of%.

  Further, the amount of the compound of formula (A1) and / or the compound of formula (A2) is 15 to 70% by mass, and the total amount of the compound of formula (B) and the compound of formula (C) is 30 to 85% by mass. Is preferably used.

Further, R ¹ in the formula (A1) may contain an alkylene group having 2 to 20 carbon atoms.
R ^{2 in} A2) may contain an alkylene group having 3 to 20 carbon atoms.

  X in the formula (B) is a numeric value of 2 to 6, y is a numeric value of 6 to 12, and z is a numeric value of 1 to 5, or x in the formula (B) is a numeric value of 2 to 10, It is preferable that y represents a numerical value of 13 to 28, and z represents a numerical value of 1 to 9.

  As the polyamide 12 thermoplastic elastomer, those having a melting point of 145 to 176 ° C. and a flexural modulus of 60 to 500 MPa can be suitably used. Considering heat resistance and prevention of cracking, it is more preferable that the melting point is 150 to 162 ° C. and the flexural modulus is 65 to 250 MPa. When a polyamide 12 thermoplastic elastomer having a melting point of less than 145 ° C. or a flexural modulus of less than 60 is used, it is assumed that the magnet material as a whole is improved in flexibility, but heat resistance, tensile strength, etc. are reduced. It is not preferable. On the other hand, when the flexural modulus exceeds 500 MPa, the effect of improving the flexibility is low, and it is difficult to improve the amount of bending deflection to a level that is effective in preventing the occurrence of cracks.

The magnetic material of the magnetic pole forming ring 27 used in the present invention has a higher maximum energy product BHmax than that of a rubber ferrite magnet, specifically 1.63 to 2.38 MGOe (13 to 19 kJ / m ³ ). Flexural properties that maintain high magnetic properties as a ferrite-based magnet in the range of 2 to 10 mm and at the same time the bending deflection at 23 ° C. (thickness t = 3.0 mm, ASTM D790; span distance 50 mm) falls within the range of 2 to 10 mm. It is excellent in crack resistance.

  In order to achieve the magnetic properties, the amount of bending deflection, etc., the magnet material of the present invention is composed of 86 to 92% by weight of anisotropic strontium ferrite and 1 to 7 polyamide 12 thermoplastic elastomer as the main materials. % By weight, and polyamide 12 is 1 to 13% by weight. Further, in order to achieve an amount of bending deflection and improve crack resistance, at least one specific plastic selected from benzenesulfonic acid alkylamides, toluenesulfonic acid alkylamides, and hydroxybenzoic acid alkylesters is used. The agent may be contained in an amount of about 0.1 to 4% by weight in the total weight.

  Specific examples of benzenesulfonic acid alkylamides include benzenesulfonic acid propylamide, benzenesulfonic acid butyramide, and benzenesulfonic acid 2-ethylhexylamide. Specific examples of toluenesulfonic acid alkylamides include N-ethyl-o- or N-ethyl-p-toluenesulfonic acid butyramide, N-ethyl-o- or N-ethyl-p-toluenesulfonic acid 2- Examples include ethylhexylamide. Specific examples of the hydroxybenzoic acid alkyl esters include ethylhexyl o- or p-hydroxybenzoate, hexyldecyl o- or p-hydroxybenzoate, o- or ethyldecyl hydroxybenzoate, o- or p- Mention may be made of octyl hydroxybenzoate, decyldodecyl o- or p-hydroxybenzoate, dodecyl o- or p-hydroxybenzoate, and the like. Among these, benzenesulfonic acid butyramide, ethyl hexyl p-hydroxybenzoate, and hexyldecyl p-hydroxybenzoate are particularly preferable from the viewpoint of compatibility with the resin, low bleed-out property, and heat resistance. Further, in addition to the above compounding materials, various additives such as a silane coupling agent and an antioxidant for improving the dispersibility of ferrite and the adhesion between polyamides may be added.

  Further, as the material of the slinger, an iron-based magnetic material is used from the usage environment without deteriorating the magnetic characteristics of the encoder magnet, and it can be appropriately selected depending on the attachment position of the slinger in view of corrosion resistance and cost. As the iron-based magnetic material, magnetic materials such as ferritic stainless steel (SUS430, etc.) and martensitic stainless steel (SUS410, SUS420, etc.) having a certain level or more of corrosion resistance are most preferable. In addition, this stainless steel slinger surface can be obtained by applying a bright finish such as BA5 if the adhesive is selected. 2B finishes can be used, but in order to improve the bondability with the magnet material, mechanical roughening such as shot blasting or rough etching with chemical etching performed in the following steps It is preferable to perform the surface treatment.

  In the first step, after the surface of the slinger is cleaned with an alkaline degreasing agent, it is dipped in dilute hydrochloric acid at room temperature for several minutes and pickled, and then an iron oxalate treatment solution containing at least oxalate ions and fluorine compound ions For several minutes to form an iron oxalate film on the surface. In the second step, the back yoke made of magnetic stainless steel on which this iron oxalate film is formed is immersed in an aqueous solution of nitric acid-hydrofluoric acid mixed acid for several minutes at room temperature so that the underlying stainless steel is not immersed. Until then, most of the iron oxalate film is removed, and the chemically etched unevenness is formed on the surface of the back yoke. Since these irregularities are formed chemically, there is no shape dependency compared to mechanical irregularities by shot blasting etc., and it is uniformly formed on the entire surface, and the inner space of the concave part is partially widened It becomes a sharp (cornered) concave-convex shape. Adhesives can easily enter into the unevenness of this slinger, and the adhesive is applied to the slinger and insert-molded using a core that has been baked in the latter-half-cured state. A stronger adhesion state can be achieved compared to the one used.

  Furthermore, you may perform the 3rd process of improving rust prevention property or the adhesiveness of an adhesive agent. A specific example of the treatment to improve rust prevention is the iron oxalate film treatment used in the second step, but it is formed with fine crystals that do not cover the uneven surface formed in the second step. A thin film is preferred. As a means for obtaining this fine crystal, a method of forming a crystal nucleus by immersing in a surface conditioning solution before the treatment is effective.

  A silane coupling agent treatment is effective as a treatment for improving the adhesiveness of the adhesive. The silane coupling agent film acts as a primer for the adhesive, and preferably has an amino group, an epoxy group, etc. that are highly reactive with the functional group of the adhesive at one end, specifically, γ-aminopropyltriethoxysilane. Γ-glycidoxypropyltriethoxysilane, etc., which are formed by dipping in a dilute solution such as alcohol and drying as necessary. The thickness of the film formed in the third step is 0.01 to 1.0 μm, more preferably 0.01 to 0.5 μm. When the thickness of the film is less than 0.01 μm, the effect of improving rust prevention and adhesiveness becomes poor, which is not preferable. On the other hand, if the thickness of the film exceeds 1.0 μm, the ratio of covering the uneven surface provided in the second step increases, which is not preferable. The unevenness state of the surface of the slinger obtained through the second step or the third step is 0.2 to 2.0 μm at the arithmetic average height Ra defined by JIS B 0601 (2001), and the maximum height. Rz is about 1.5 to 10 μm. If the unevenness is less than the lower limit, it becomes difficult to exhibit the wedge effect. On the other hand, when the unevenness exceeds the upper limit value, the wedge effect is improved accordingly, but it becomes difficult to achieve by the chemical etching method, the practicality is lowered, and the rubber seal lip with which the back side of the slinger is in contact with This is not preferable because the sealing performance is reduced.

  Moreover, in the case of ferrous magnetic materials other than magnetic stainless steel, for example, cold-rolled steel sheets such as SPCC, the surface treatment liquid used in the first step is made of zinc ions, nickel ions, cobalt ions, calcium ions and manganese ions. To carry out other steps in the same manner by changing to one containing at least one heavy metal ion selected from the group consisting of and a phosphate ion, specifically a zinc phosphate treatment solution, a manganese phosphate treatment solution, etc. As a result, irregularities are formed by chemical etching.

  In the encoder of the present embodiment, an adhesive enters the unevenness provided by chemical etching or the like, and maintains a strong adhesive state with the metal side. This adhesive layer is an adhesive that undergoes a curing reaction at the time of insert molding, and is in a semi-cured state to such an extent that it is not detached and washed away by the high-pressure plastic magnet material melted at the time of insert molding. Alternatively, in addition to this, the resin is completely cured by secondary heating after molding. Adhesives that can be used can be diluted with a solvent, and phenol resin adhesives and epoxy resin adhesives that progress in a two-step curing reaction are considered in consideration of heat resistance, chemical resistance, and handling properties. It is preferable.

  The phenol resin-based adhesive is preferably used as a rubber vulcanized adhesive, and the composition is not particularly limited, but a novolac-type phenol resin, a resol-type phenol resin, and a curing agent such as hexamethylenetetramine. Can be used in which methanol or methyl ethyl ketone is dissolved. Moreover, in order to improve adhesiveness, you may mix these with a novolak-type epoxy resin.

  As the epoxy resin adhesive, a one-pack type epoxy adhesive that can be diluted into a solvent is suitable as a stock solution. This one-pack type epoxy adhesive, after evaporating the solvent, becomes a semi-cured state on the slinger surface at an appropriate temperature and time so as not to be washed away by the high-temperature and high-pressure molten resin at the time of insert molding. The resin is completely cured by heat from the resin and secondary heating.

  The one-pack type epoxy adhesive used in the present embodiment is composed of at least an epoxy resin and a curing agent, and the curing agent hardly undergoes a curing reaction near room temperature, for example, becomes a semi-cured state at about 80 to 120 ° C. By applying high-temperature heat of ˜180 ° C., the thermosetting reaction proceeds completely. This adhesive was stressed by other epoxy compounds used as reactive diluents, curing accelerators that improve the thermal cure rate, inorganic fillers that have the effect of improving heat resistance and strain resistance, and stress Cross-linked rubber fine particles or the like that improve flexibility that sometimes deforms may be further added.

  As the epoxy resin, those having two or more epoxy groups in the molecule are preferable in that a crosslinked structure capable of exhibiting sufficient heat resistance can be formed. Also, 4 or less, and further 3 or less are preferable from the viewpoint that a low-viscosity resin composition can be obtained. If the number of epoxy groups contained in the molecule is too small, the heat resistance of the cured product tends to decrease and the strength tends to decrease. On the other hand, if the number of epoxy groups contained in the molecule is too large, the resin This is because the viscosity of the composition increases and the curing shrinkage tends to increase.

  The number average molecular weight of the epoxy resin is preferably 200 to 5500, particularly preferably 200 to 1000 from the viewpoint of balance of physical properties. If the number average molecular weight is too small, the strength of the cured product tends to decrease and the moisture resistance tends to decrease.On the other hand, if the number average molecular weight is too large, the viscosity of the resin composition increases and workability adjustment is possible. This is because there is a tendency that the use of a reactive diluent increases.

  Furthermore, the epoxy equivalent of the epoxy resin is preferably 100 to 2800, particularly 100 to 500 from the viewpoint that the blending amount of the curing agent is within an appropriate range. If the epoxy equivalent is too small, the amount of the curing agent will increase too much and the physical properties of the cured product will deteriorate. On the other hand, if the epoxy equivalent is too large, the amount of the curing agent will decrease and the epoxy resin will decrease. This is because the molecular weight of the resin itself tends to increase and the viscosity of the resin composition increases.

  Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, glycidylamine type epoxy resin, alicyclic epoxy resin, dicyclopentadiene. Type epoxy resin, phenol novolac type epoxy resin, polyester modified epoxy resin, copolymer with other polymers such as silicon modified epoxy resin, and the like. Among these, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, naphthalene type epoxy resin, phenol novolac type epoxy resin, etc. have a relatively low viscosity and excellent heat resistance and moisture resistance of the cured product. Therefore, it is preferable.

  As the curing agent, an amine curing agent, a polyamide curing agent, an acid anhydride curing agent, a latent curing agent, or the like can be used.

  The amine-based curing agent is an amine compound and does not generate an ester bond by a curing reaction. Therefore, the amine-based curing agent is preferable because it has excellent moisture resistance as compared with the case where an acid anhydride-based curing agent is used. As the amine compound, any of an aliphatic amine, an alicyclic amine, and an aromatic amine may be used, but the aromatic amine is most preferable because the storage stability of the blend at room temperature is high and the cured product has high heat resistance. .

  As aromatic amines, 3,3′-diethyl-4,4′-diaminodiphenylmethane, 3,5-diethyl-2,6-toluenediamine, 3,5-diethyl-2,4-toluenediamine, 3,5 Examples thereof include a mixture of diethyl-2,6-toluenediamine and 3,5-diethyl-2,4-toluenediamine, and the like.

  The polyamide-based curing agent is also called a polyamidoamine, and is a compound having a plurality of active amino groups in the molecule and similarly having one or more amide groups. A polyamide-based curing agent synthesized from polyethylene polyamine is preferable because it produces an imidazirine ring by secondary heating and improves compatibility with the epoxy resin and mechanical properties. The polyamide curing agent may be an adduct type in which a small amount of epoxy resin has been reacted in advance, and by using the adduct type, the compatibility with the epoxy resin is excellent, and the curing drying property and water / chemical resistance are improved. preferable. By using this polyamide-based curing agent, a tough cured resin having a particularly high flexibility is obtained by crosslinking with the epoxy resin, and therefore, it is excellent in the thermal shock resistance required for the magnetic encoder of the present invention, and is suitable.

  Cured products cured with acid anhydride curing agents have high heat resistance and excellent mechanical and electrical properties at high temperatures, but tend to be somewhat brittle, but are curing accelerators such as tertiary amines. Can be improved by combining with. Examples of acid anhydride-based curing agents include phthalic anhydride, methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, methyleneendomethylenetetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, trimellitic anhydride, etc. Can do.

  The latent curing agent has excellent storage stability at room temperature in a mixed system with an epoxy resin, and cures rapidly under conditions of a certain temperature or more. As an actual form, a curing agent for an epoxy resin Neutral salts or complexes of acidic or basic compounds that can be activated when heated, those that harden in microcapsules and break down by pressure, crystalline, high melting point, compatible with epoxy resins at room temperature There are some materials that are not dissolved by heating.

  As the latent curing agent, 1,3-bis (hydrazinocarboethyl) -5-isopropylhydantoin, eicosanedioic acid dihydrazide, adipic acid dihydrazide, dicyandiamide, 7,11-octadecadien-1 which is a high melting point compound , 18-dicarbohydrazide and the like. Among these, 7,11-octadecadien-1,18-dicarbohydrazide is used as a curing agent, and thus becomes a tough cured resin rich in flexibility by crosslinking with an epoxy resin. It is excellent in thermal shock resistance required for the magnetic encoder of the invention and is suitable.

  As the reactive diluent, t-butylphenyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, or the like can be used. Flexibility can be imparted. However, these reactive diluents, when used in a large amount, reduce the moisture resistance and heat resistance of the cured product, and therefore, preferably 30% or less, more preferably 20%, based on the weight of the main epoxy resin. It is added in the following ratio.

The curing accelerator is preferably one that has sufficient storage stability without accelerating the curing reaction at room temperature and rapidly proceeds with the curing reaction when the temperature reaches 100 ° C. or higher. And compounds having one or more ester bonds produced by the reaction of 1-alkoxyethanol and carboxylic acid. This compound is for example represented by the general formula (I):
^{R 3 [COO-CH (OR} 2) -CH 3] n (I)
(In the formula, R ³ is an n-valent hydrocarbon group having 2 to 10 carbon atoms and optionally containing one or more of nitrogen atom, oxygen atom, etc., R ² is 1 to 6 carbon atoms, A monovalent hydrocarbon group which may contain one or more of a nitrogen atom, an oxygen atom and the like, and n is an integer of 1 to 6. A specific example is shown in Chemical Formula 5.

As another example, the compound of R ² is a propyl group in R ³ is a divalent phenyl radical, in R ³ is a trivalent phenyl group the compound of R ² is a propyl group, with R ³ is a tetravalent phenyl group Examples thereof include compounds in which R ² is a propyl group. These may be used alone or in combination of two or more. Among these, the compound represented by Chemical formula 5 is most preferable from the viewpoint of the balance between curing reactivity and storage stability.

  In addition to the compounds described above, imidazole compounds such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, and 2-phenylimidazole may be used as the curing accelerator.

  Further, as a curing accelerator, a carboxylic acid such as adipic acid, which is a compound having active hydrogen that reacts with an epoxy group to cause a ring-opening reaction, may be used. By using adipic acid as a curing accelerator, it reacts with the epoxy group of the epoxy resin and the amino group of the curing agent, and the resulting cured product becomes flexible as the amount of adipic acid added increases. In order to express flexibility, the amount of adipic acid added is 10 to 40% by weight, more preferably 20 to 30% by weight, based on the total amount of the adhesive. When the addition amount is less than 10% by weight, sufficient flexibility is not exhibited. On the other hand, when the addition amount exceeds 40% by weight, the total amount of the epoxy resin in the adhesive is reduced correspondingly, and the adhesive force and mechanical strength are lowered. Since adipic acid is also a starting material for polyamide resin, when the binder of magnetic powder is a polyamide resin such as polyamide 12 or polyamide 6, it reacts with a monomer or oligomer component remaining in a trace amount in the binder material itself. The adhesive composition contains adipic acid, and stronger adhesion is possible.

  Further, as a curing accelerator, a tertiary amine such as dimethylbenzylamine, a quaternary ammonium salt such as tetrabutylammonium bromide, which acts as a catalyst for promoting a ring-opening reaction of an epoxy group, 3- (3 ′, 4′-dichlorophenyl) An alkyl urea such as -1,1-dimethylurea may be added.

  The OH groups generated by the ring-opening reaction, including the amines described above, form hydrogen bonds with the hydroxyl groups on the metal surface, which is the adherend, and also act on the amide bonds of nylon, which is the binder material. And can maintain a strong adhesive state.

  The inorganic filler can be used without particular limitation as long as it is conventionally used. Examples thereof include fused silica powder, quartz glass powder, crystalline glass powder, glass fiber, alumina powder, talc, aluminum powder, and titanium oxide.

  As the crosslinked rubber fine particles, those having a functional group capable of reacting with an epoxy group are preferred, and specifically, vulcanized acrylonitrile butadiene rubber having a carboxyl group in the molecular chain is most preferred. A finer particle diameter is preferable, and an ultrafine particle having an average particle diameter of about 30 to 200 nm is most preferable in order to exhibit dispersibility and stable flexibility.

  The one-component epoxy adhesive described above hardly undergoes a curing reaction at room temperature, for example, becomes semi-cured at about 80 to 120 ° C., and is completely cured by applying high-temperature heat at 120 to 180 ° C. The reaction proceeds. More preferably, the curing reaction proceeds at a temperature of 150 to 180 ° C. in a relatively short time, and the one that can be bonded by high-frequency heating at about 180 ° C. is most preferable.

  The cured product after the thermosetting of the phenol resin-based adhesive and the epoxy resin-based adhesive described above has a physical property of flexural modulus or Young's modulus of 0.02 to 5 GPa, more preferably 0.03 to 4 GPa. Yes, or hardness (durometer D scale; HDD) is preferably in the range of 40 to 90, more preferably 60 to 85. When the flexural modulus or Young's modulus is less than 0.02 GPa or the hardness (HDD) is less than 40, the adhesive itself is too soft and easily deforms due to vibrations during running of an automobile or the like, and thereby the magnet part moves easily. For this reason, the detection accuracy of the rotational speed may be lowered, which is not preferable. On the other hand, if the flexural modulus or Young's modulus exceeds 5 GPa or the hardness (HDD) exceeds 90, the adhesive itself is too hard and the thermal expansion / contraction difference between the magnet of the magnetic encoder and the fixing member (that is, both It is difficult to deform so as to absorb the difference in expansion / contraction amount due to the difference in linear expansion coefficient, and in the worst case, there is a possibility that a crack or the like may occur in the magnet. The one-pack type epoxy adhesive of the present invention is required to have thermal shock resistance when used in an automobile, and more preferably has flexibility (deforms when stressed) in a cured state.

  Hereinafter, the manufacturing method of the magnetic encoder of the present invention using the above materials will be described in detail. First, the surface of the slinger is roughened with chemical etching in the above-described step, and the surface is roughened as shown in the cross-sectional electron micrograph of FIG. Then, injection molding (insert molding) of a plastic magnet material using a slinger with a glue baked in a semi-cured state on the surface as a core is performed using a magnetic field injection molding machine 80.

  As shown in FIG. 5, 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. 6A, 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. 6B, an annular space for accommodating the cylindrical fitting portion of the slinger 25 is formed between the movable side mold pieces 89a and 89b, and the fixed side mold located at the center. The mold piece 90a protrudes toward the movable mold 89 from the fixed mold piece 90b located on the outer diameter side, and the fixed mold piece 90a overlaps the accommodated slinger 25 in the radial direction. Located.

  In addition, when a 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 generate them. The plastic magnet material is magnetized with a magnetic field in one direction (with the same polarity) to align 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 for a certain time in a thermostatic bath or the like. 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 the subsequent process, multipole magnetization is performed by superimposing with a known magnetizing yoke to complete the manufacture of the magnet part. The number of poles of the magnet portion 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 practicality is low.

  In addition, as described above, the encoder part is molded by a disk gate type injection molding (insert) in which the plastic magnet material melted from the inner diameter thick part simultaneously flows into the mold at a high pressure and is rapidly cooled and solidified in the mold. Molding) is preferred. The molten resin spreads in a disk shape, and then flows into the mold corresponding to the inner diameter thick portion, whereby the flake-like magnetic powder contained therein is oriented in 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 higher orientation and is very close to the axial anisotropy oriented in the thickness direction. If a magnetic field is applied to the mold in the thickness direction during molding, the anisotropy becomes closer to perfection.

  Even when magnetic field molding is performed, if the gate is a side gate other than a disk gate, for example, the orientation at the weld is completely anisotropic in the process of gradually increasing the resin viscosity toward solidification. It is difficult to do so, which may cause cracks and the like due to long-term use of the weld portion where the magnetic properties are lowered and the mechanical strength is lowered. Therefore, in the present embodiment, insert molding by a disk gate is performed in a state where a slinger is used as a core and a magnetic field is applied in the thickness direction.

  Note that the color of the magnetic pole forming ring 27 of the molded magnetic encoder 26 is black because of the ferrite powder, but it slightly changes depending on the additive. As shown in FIG. 2, the magnet material also wraps around the outer peripheral portion of the flange portion of the slinger 25 and is mechanically joined.

  According to the magnetic encoder of the present embodiment, the magnet portion is made of a plastic magnet material including a thermoplastic resin containing 86 to 92% by weight of magnetic powder as a binder, and the magnet portion is an adhesive that undergoes a curing reaction during insert molding. The magnet part is chemically bonded to the slinger made of magnetic material by the agent, so the magnet section has good magnetic properties and enables multi-pole magnetization in the circumferential direction at a fine pitch, and the entire magnet The strength of the can be ensured.

  Further, according to the magnetic encoder of the present embodiment, the magnet portion is made of a magnet material containing ferrite-based magnetic powder and a thermoplastic resin, and the magnet portion is integrally joined to the slinger made of the magnetic material. Has a thickness of 3.0 mm and a bending deflection at 23 ° C. in the range of 2 to 10 mm. Therefore, the bending deflection is increased to improve the crack resistance. Therefore, even in a structure in which the slinger is used as a core and mechanically joined by insert molding, stress such as high temperature, low temperature, and thermal shock at the time of transition between high and low temperatures is applied to the magnet part. When this occurs, it is possible to effectively prevent cracks from occurring in the magnet portion, and to significantly improve the reliability. The amount of bending deflection is given by containing a thermoplastic elastomer such as polyamide 12 as a binder.

  Further, according to the magnetic encoder of the present embodiment, the slinger is made of a rough iron-based magnetic material accompanied by a chemical etching process, so that the adhesive effect of the adhesive improves the adhesion between the slinger and the magnet part. ing.

  In addition, by using phenolic adhesives or epoxy adhesives as adhesives, various agents such as high temperature, low temperature, thermal shock at the time of transition between high temperature and low temperature, grease and oil are exposed to the undercarriage of automobiles Therefore, the possibility of peeling or the like in the bonded portion is low and the reliability is improved. In addition, by using an adhesive that can be cured in two stages and insert molding in a state in which a semi-cured adhesive is baked, the slinger and the magnet can be joined mechanically and chemically. Productivity and reliability are further improved.

(Second Embodiment)
Next, a wheel support rolling bearing unit for supporting a non-driven wheel, which is supported by an independent suspension, according to a second embodiment of the present invention will be described in detail. In addition, the same code | symbol is attached | subjected about a part equivalent to 1st Embodiment, and description is abbreviate | omitted or simplified.

  In the first embodiment, the magnetic encoder 26 and the sensor 28 face each other in the axial direction. However, in this embodiment, as shown in FIG. 7, the magnetic encoder 31 and the sensor 32 face each other in the radial direction. ing.

In the magnetic encoder 31 of the present embodiment, an annular slinger 33 as a fixing member is fitted and fixed to the outer peripheral surface of the inner end portion of the inner ring 16a, and on the inner peripheral surface of the slinger 33 extending in the axial direction from the inner ring 16a. A magnetic pole forming ring 34 as a magnet portion is attached. Further, a cover member 35, which is a stationary member, is fixed to the outer peripheral surface of the outer ring 5a so as to cover the end portion in the axial direction of the bearing unit 2a, and the sensor 32 has a magnetic pole in the opening formed in the cover member 35. It is attached so as to face the forming ring 34 in the radial direction.
The composition and molding method of the magnetic encoder 31 are the same as those in the first embodiment.

  Therefore, according to the magnetic encoder 31 of the present embodiment, the diameter of the detected surface can be increased with respect to the same space as compared with the magnetic encoder facing in the axial direction. Can be large and easy to manufacture.

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

  As shown in FIGS. 8 and 9, the rolling bearing unit 40 including the magnetic encoder according to the present embodiment includes an outer ring 41 that is a fixed ring, an inner ring 42 that is a rotating ring (rotating body), an outer ring 41, and an inner ring. Balls 43, which are a plurality of rolling elements that are rotatably arranged in an annular gap defined by 42 and are held at equal intervals in the circumferential direction by a retainer 44, and an opening end of the annular gap The sealing device 45, the magnetic encoder 46, and the sensor 47 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. . The magnetic encoder 46 includes a slinger 60 and a magnet portion 70 attached to the slinger 60. The magnet portion 70 is fixed to the inner ring 42 with the slinger 60 as a fixing member.

  The seal member 50 is configured by reinforcing a seal lip 52 similarly 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 front end portion of the seal lip 52 is branched into a plurality of sliding contact portions, and each sliding contact portion is formed on the end surface facing the bearing inward of the flange portion 62 of the slinger 60 or the outer peripheral surface of the fitting portion 61. They are in sliding contact with each other around the circumference. Thereby, a high sealing force is obtained.

The slinger 60 is formed in an annular shape having an L-shaped cross section, and has a substantially cylindrical fitting portion 61 that is fitted on the outer peripheral surface of the inner ring 42, and a hook-like shape that is radially expanded from one end of the fitting portion 61 The flange portion 62 and a protruding portion 63 that protrudes outward in the axial direction from the flange portion 62 on the inner diameter side of the flange portion 62 by bending one end portion of the fitting portion 61. Further, the outer peripheral surface of the protruding portion 63 is provided with notch portions 64 formed at a plurality of locations in the circumferential direction. A magnet portion 70 that changes a nearby magnetic field (for example, magnetic flux density) in synchronization with the rotation of the inner ring 42 is joined to an end surface (hereinafter referred to as a joining surface) 62a of the flange portion 62 facing the outside of the bearing. ing. At the same time, the magnet portion 70 is also mechanically joined to the outer peripheral portions of the notch portion 64 and the flange portion 62.
The composition and molding method of the magnetic encoder 46 are the same as those in the first embodiment.

  Therefore, according to the magnetic encoder of the present embodiment, the melted magnet material is not only in the outer diameter portion of the flange portion 62 of the slinger 60 but also in a plurality of notch portions provided in the circumferential direction of the protruding portion 63 provided on the inner diameter side. Also flows and is mechanically joined. As a result, the contraction of the magnet material is received not only by the outer diameter portion of the flange portion 62 but also by the protruding portion 63 on the inner diameter side, thereby further reducing the frequency of occurrence of cracks in the magnet portion caused by thermal shock or the like. Can do.

In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.
For example, the magnetic encoder according to the present embodiment can be applied to any bearing unit of each embodiment.

  Hereinafter, the present invention will be further described with reference to examples and comparative examples, but the present invention is not limited thereto.

  First, in the magnetic encoder manufactured by insert molding using the slinger as a core according to the present invention, a test was conducted on the adhesion state due to the difference in surface treatment.

(Example 1)
Unevenness was formed by chemically etching the iron oxalate film formed on the surface of SUS430. The arithmetic average height Ra of the unevenness was 0.9 μm, and the maximum height Rz was 4.5 μm. Then, a 30% solid content phenol resin adhesive (Metal Lock N-15 manufactured by Toyo Chemical Laboratories Co., Ltd.) mainly composed of a resol type phenol resin was further diluted three times with methyl ethyl ketone and applied to the slinger surface by dipping treatment. . 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. The SUS430 plate material baked with this adhesive is set in a mold, and this is used as a core for plastic magnet material (Strontium ferrite-containing 12 nylon-based anisotropic plastic magnet compound “FEROTOP TP-A27N” manufactured by Toda Kogyo Co., Ltd.) An amount of 91% by weight)) was insert-molded from the inner periphery with a disc gate. A gate cut was performed immediately after molding, and the adhesive was completely cured by secondary heating at 130 ° C. for 1 hour to obtain a test body of Example 1.

(Example 2)
Example 2 was carried out in the same manner as in Example 1, except that the surface of SUS430 was made uneven by shot blasting, the arithmetic average height Ra of the unevenness was 0.8 μm, and the maximum height Rz was 5.0 μm. The test body was obtained.

  Table 1 below shows the results of pulling the hooked portion of the outer periphery of the encoder after curing with pliers.

  As is apparent from Table 1, the unevenness caused by the chemical etching treatment has a shape in which the inside of the recess is widened (see FIG. 4), although the surface roughness is hardly different by the unevenness treatment (see FIG. 4). As a result, it can be seen that the adhesive is firmly attached to the metal side.

  Next, as shown in Table 2 below, a thermal shock test was performed by changing the composition of the magnet material of the magnet portion.

  As the surface treatment of the slinger, a chemiblast treatment made by Nihon Parkerizing was performed in the same manner as in Example 1 above. Specifically, irregularities were formed by chemically etching an iron oxalate film formed on the surface of a plate material made of SUS430 having a thickness of 0.6 mm. The arithmetic average height Ra of the irregularities was 0.2 to 0.3 μm, and the maximum height Rz was 1.8 to 3.1 μm.

  Then, a 30% solid content phenol resin adhesive (Metal Lock N-15 manufactured by Toyo Chemical Laboratories Co., Ltd.) mainly composed of a resol type phenol resin was further diluted three times with methyl ethyl ketone and applied to the slinger surface by dipping treatment. . 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. The SUS430 plate material baked with this adhesive was set in a mold, and the core material was used as a core for insert molding of the magnet material from the inner peripheral portion with a disk gate. Immediately after molding, the gate was cut and further heated at 150 ° C. for 1 hour to completely cure the adhesive.

  After that, the thermal shock that repeats 30 minutes at 120 ° C and 30 minutes at -40 ° C with the encoder part (inner diameter 66mm, outer diameter 76mm, magnet part thickness 0.9mm) obtained by molding and integration with the slinger A test was conducted. Ten samples of each of Examples 3 and 4 and Comparative Example 1 were put, and cracks generated in the magnet portion were observed every 50 cycles.

  As is apparent from Table 2, it was found that by including a PA12-based thermoplastic elastomer as a binder, the amount of bending deflection of the material itself was increased and the crack resistance was improved.

Next, the magnetic properties of the magnet material having the composition of Example 4 were measured using a magnetic field injection molding machine depending on whether or not a magnetic field was generated. The shape of the magnetic encoder is as shown in FIG. 2 and the same size as the above. In addition, the coil current at the time of magnetization was set to a sufficiently saturated value (sufficient for blending), reverse demagnetization was performed during cooling, and demagnetization was further performed to a magnetic flux density of 1 mT or less with an oil capacitor type demagnetizer. Thereafter, it was superposed on a 96 pole (NS alternating) magnetized yoke, magnetized at 1000 V and 1000 μF, and measured for magnetic flux density and pitch error at an air gap of 1 mm while rotating. The results are shown in Table 3.

  From the results in Table 3, it was confirmed that the magnetic properties were improved by performing magnetic field shaping.

Sectional drawing which shows the rolling bearing unit of 1st Embodiment of this invention. It is sectional drawing which shows the sealing device provided with the magnetic encoder of 1st Embodiment of this invention. It is a perspective view which shows the example by which the multipolar magnetization was carried out in the circumferential direction of the encoder magnet. It is a cross-sectional microscope picture which shows the surface of the slinger processed by chemical etching. 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 an expanded sectional view which shows the rolling bearing unit of 2nd Embodiment of this invention. It is sectional drawing which shows the rolling bearing unit of 3rd Embodiment of this invention. It is sectional drawing which shows the sealing apparatus provided with the magnetic encoder of 3rd Embodiment of this invention. It is sectional drawing which shows the conventional rolling bearing unit.

Explanation of symbols

2a Wheel support rolling bearing unit 5a Outer ring 7a Hub 8 Stud 10a, 10b Outer ring raceway 11 Coupling flange 12 Mounting flange 14a, 14b Inner ring raceway 15 Small diameter step 16a Inner ring 17a Ball 18 Cage 21a, 21b Seal rings 22a, 22b Elastic material 23 Caulking portion 24b Core metal 25 Slinger 26 Magnetic encoder 27 Magnetic forming ring

Claims (10)

A magnetic encoder comprising: a fixing member that can be attached to a rotating body; and a substantially annular magnet portion that is attached to the fixing member and is multipolarly magnetized in the circumferential direction,
The magnet part is made of a plastic magnet material containing a thermoplastic resin containing 86 to 92% by weight of magnetic powder as a binder,
The magnetic encoder, wherein the magnet portion is chemically joined to the fixing member made of a magnetic material by an adhesive that undergoes a curing reaction during insert molding. A magnetic encoder comprising: a fixing member that can be attached to a rotating body; and a substantially annular magnet portion that is attached to the fixing member and is multipolarly magnetized in the circumferential direction,
The magnet part is made of a magnet material containing a ferrite magnetic powder and a thermoplastic resin,
The magnet portion is integrally joined to the fixing member made of a magnetic material,
The magnetic part has a thickness of 3.0 mm and a bending deflection at 23 ° C. in the range of 2 to 10 mm.   The magnetic encoder according to claim 1 or 2, wherein the fixing member is made of a roughened iron-based magnetic material accompanied by a chemical etching process.   The said thermoplastic resin consists of a mixture containing the polyamide-type thermoplastic elastomer which uses polyamide as a hard segment, and at least 1 chosen from the group of the polyamide 12, the polyamide 11, and the polyamide 612. The magnetic encoder in any one of.   The said thermoplastic resin contains the polyamide 12 type | system | group thermoplastic elastomer which is a block copolymer which has the hard segment of polyamide 12, and the soft segment of a polyether component, The Claim 1 characterized by the above-mentioned. Magnetic encoder.   The magnetic encoder according to claim 1, wherein the magnetic powder contains at least strontium ferrite.   The magnetic encoder according to claim 1, wherein the adhesive is at least one selected from the group of a phenol resin adhesive and an epoxy resin adhesive.   The magnetic encoder according to claim 1, wherein a maximum energy product BHmax as a magnet material of the magnet portion is in a range of 1.63 to 2.38 MGOe.   The fixed wheel, the rotating wheel, a plurality of rolling elements disposed so as to be freely rollable in the circumferential direction between the fixed wheel and the rotating wheel, and fixed to the rotating wheel. A rolling bearing unit comprising the magnetic encoder according to claim 1. A method of manufacturing a magnetic encoder comprising: a fixing member that can be attached to a rotating body; and a substantially annular magnet portion that is attached to the fixing member and is multipolarly magnetized in the circumferential direction,
Injecting a molten plastic magnet material into a mold attached to a magnetic field injection molding machine using the fixing member baked in a semi-cured state on the surface as a core,
In combination with the injection step, applying a coil current to the coils at both ends of the mold to magnetize the plastic magnet material with a generated unidirectional magnetic field;
When the plastic magnet material is cooled in the mold, the polarity reverses alternately, starting with demagnetization that demagnetizes with a magnetic field opposite to the magnetization direction, and an initial coil current higher than the coil current at the time of magnetization. And demagnetizing by at least one of reversal demagnetization to demagnetize by applying a plurality of pulse currents gradually decreasing in amplitude to the coil of the mold,
A method for manufacturing a magnetic encoder, comprising: demagnetizing to a magnetic flux density of 2 mT or less with a demagnetizer and then superimposing it on a magnetized yoke to perform multipolar magnetization.