JP4312149B2 - Bearing with magnetic encoder and wheel bearing - Google Patents

Description

  The present invention relates to a bearing with a magnetic encoder and a wheel bearing, and for example, relates to a wheel bearing provided with a magnetic encoder of a rotation detection device for detecting front and rear wheel rotational speeds in an antilock brake system of an automobile.

Conventionally, the following structure is often used as an anti-skid rotation detection device for preventing automobile skid. That is, the rotation detection device is composed of a toothed rotor and a sensing sensor, and in this case, the rotation detection device is generally arranged apart from the seal device for sealing the bearing, and constitutes an independent rotation detection device. Is.
Such a conventional example has a structure in which a toothed rotor fitted to a rotating shaft is sensed and detected by a rotation detection sensor attached to a knuckle, and a bearing used is provided independently on the side thereof. Protected against intrusion of moisture or foreign matter by the sealed device.

As another example, Patent Document 1 discloses a bearing seal having a rotation detection device for detecting wheel rotation for the purpose of reducing the mounting space of the rotation detection device and dramatically improving the sensing performance. A structure is shown in which an elastic member mixed with magnetic powder is circumferentially vulcanized and bonded in the radial direction of a slinger to be used, and magnetic poles are alternately arranged there.
Further, in Patent Document 2, for the purpose of reducing the dimension in the axial direction, improving the degree of sealing between the rotating member and the fixed member, and enabling easy attachment, the gap between the rotating member and the fixed member is disclosed. Is shown, and a rotating disk is attached to the rotating member, and a multi-polar coder is attached to the rotating disk. The coder used is made of an elastomer to which magnetic particles are added, and the side surface of the coder is a sealing means that is substantially flush with the side surface of the fixing member.

A coder made of plastic (plastomer) containing magnetic powder or magnetic particles is shaped by using a mold suitable for the product shape, as in conventional injection molding or compression molding. Or by forming a sheet by extrusion molding using a T-shaped die or sheet molding such as calendering, and then punching it into a product shape, and then bonding and fixing on a metal substrate with an adhesive You may make it. In this case, the metal substrate may be assembled in advance in the mold as in the case of insert molding, and then the molten resin may be poured and the bonding process may be simultaneously processed.
Japanese Patent No. 2816783 JP-A-6-281018 JP-A 63-115008 JP-A-63-300910

  However, among the above conventional examples, in the bearing seals shown in Patent Document 1 and Patent Document 2, an elastic member mixed with magnetic powder in the radial direction of the slinger used therein is vulcanized and bonded in a circumferential shape. Or, if the coder is to be an elastomer with magnetic particles added as a coder built-in sealed structure with a multipolar coder attached, an elastomer or elastic member component that becomes a binder for holding magnetic powder or magnetic particles is required. Become. However, when an elastomer or elastic member component is used for the binder, a dispersion step is always required by kneading the magnetic powder or magnetic particles with the elastomer or elastic member before shaping into the coder shape. In this step, the binder component in the coder Since it is difficult to increase the relative content (volume fraction) of magnetic powder or magnetic particles, it is necessary to increase the thickness of the coder in order to obtain a magnetic force that is stably sensed by the magnetic sensor.

In addition, molding of elastic members and elastomeric coders containing magnetic powder and magnetic particles is performed by using a mold suitable for the product shape, such as injection molding and compression molding, and the vulcanization process is performed. When necessary, the vulcanization time required in the mold had to be maintained under pressure, requiring many steps in production.
In addition, elastic members and elastomeric coders containing magnetic powder and magnetic particles, for example, in bearing seals with a rotation detection device for detecting wheel rotation, reduce the mounting space for the rotation detection device and dramatically improve sensing performance. In order to improve the quality of the sensor, the sensor must be disposed at a position close to and opposite to the slinger used in the axial direction. However, in this case, if foreign particles such as sand particles enter the gap between the bearing seal surface on the rotating side and the surface of the sensing sensor on the fixed side while the vehicle is running, the elastic member and the elastomer coder surface will be worn. Severe damage was observed.

  In the case of a coder made of plastic (plastomer) containing magnetic powder or magnetic particles, it is manufactured by conventional injection molding, compression molding, sheet molding such as extrusion molding using T-shaped dies or calendar molding, and insert molding. If it is going to do, the synthetic resin component used as a binder for hold | maintaining magnetic powder and a magnetic particle will be needed. However, when a synthetic resin component is used for a binder, a dispersion step by kneading magnetic powder, magnetic particles, plastomer, and an elastic member is always required before shaping into a coder shape, like an elastomer. Again, in this process, the relative content (volume fraction) of magnetic powder and magnetic particles with respect to the binder component in the coder is difficult to increase, so the thickness of the coder is used to obtain a magnetic force that is stably sensed by the magnetic sensor. It was necessary to increase the dimensions. In addition, pre-molding materials produced by kneading magnetic powder, magnetic particles, plastomers, and elastic members in this way by conventional manufacturing methods are injected (injected) into the mold or compressed (compressed) to be applied to the coder. When forming, or by shaping by insert molding, etc., the magnetic particle component contained in the material is a metal oxide, so it is hard and wear of molds and molding machines becomes a problem in mass production. The pre-molding material with a high content of magnetic particle components has a problem that the melt viscosity becomes high and the molding load increases, such as increasing the molding pressure and the mold clamping force.

  Even in the case of sheet molding such as extrusion molding and calendar molding using a T-shaped die, the magnetic particle component contained in the material is hard with metal oxide, so that for mass production, T-shaped die and calendar molding machine Roll wear became a problem.

  The object of the present invention is a compact configuration, which can improve the reliability and reliability of sensing for rotation detection, and is excellent in the durability and wear resistance of the magnetic encoder, compared with a case where only magnetic powder is sintered. Providing bearings with magnetic encoders and wheel bearings that can be made solid and robust, can easily form green compacts of a predetermined shape during the manufacturing process of multipolar magnets, can secure green compact strength, and are excellent in productivity. It is to be.

A bearing with a magnetic encoder according to the present invention is a rolling bearing in which a rolling element is interposed between raceways facing an inner ring and an outer ring. A magnetic encoder is attached to a rotating side wheel of the inner ring and the outer ring. Arranged on the inner side of the end face of the fixed side ring in the space between the inner ring and the outer ring, this magnetic encoder is supported by this core metal by assembling the multi-pole magnet to the metal core bar by caulking or press-fitting. be one, the multi-pole magnet, the magnetic powder and the non-magnetic metal powder and porous magnetic poles alternately in the circumferential direction becomes a mixed powder of a sintered body of porous and sintered is formed of a multi The magnetic powder and non-magnetic metal powder that are composed of a polar magnet and used for the mixed powder have an average particle diameter of 10 μm or more and 150 μm or less. The linear expansion coefficient of the multipolar magnet is 0.5 × 10 ⁻⁵ or more and 9.0 × 10 ⁻⁵ or less. The green compact before sintering the mixed powder has pores inside. The core metal is made of, for example, stainless steel.
According to this structure, since the multipolar magnet which comprises a magnetic encoder is the sintered compact which sintered the mixed powder of magnetic powder and nonmagnetic metal powder, each following advantage is acquired.
(1). Compared to conventional elastomers and plastomers, the magnetic powder ratio can be increased, so that the magnetic force per unit volume can be increased. Thereby, the detection sensitivity can be improved.
(2). Compared to a conventional sintered magnet that is sintered only with magnetic powder, it is difficult to break due to the presence of non-magnetic metal powder as a binder.
(3). Since the surface is harder than conventional elastomers, etc., it is excellent in wear resistance and hardly damaged.
(Four) . Productivity is superior to conventional elastomers.

In addition, since both the magnetic powder and the nonmagnetic metal powder used for the mixed powder have an average particle diameter of 10 μm or more and 150 μm or less, the flowability into the mold when obtaining a green compact is good and the pressure is reduced. Powder strength can be secured.
If the average particle diameter of either one or both of the magnetic powder and the nonmagnetic metal powder is smaller than 10 μm, when the green compact is obtained, it is difficult for the mixed powder to flow into the mold, and a green compact with a predetermined shape is formed. Can not. If the average particle size of one or both of these powders is larger than 150 μm, the green compact strength will not be achieved.

The magnetic powder and the nonmagnetic metal powder are mixed at a predetermined blending ratio using a powder mixer, and the mixed powder is pressure-molded in a mold at room temperature to obtain a green compact.
At this time, the sintered body made of the mixed magnetic powder mixed with the magnetic powder using the nonmagnetic metal powder as the binder is dispersed by the powder mixer while adjusting the composition ratio of the nonmagnetic metal powder and the magnetic powder. Since dry blending can be performed, the relative content (volume fraction) of the magnetic powder in the sintered body can be increased. For this reason, the magnetic force stably sensed by the magnetic sensor can be easily obtained, and there is no need to increase the thickness of the multipolar magnet.
Moreover, even in the production of sintered bodies that are multipolar magnets, the sintered powder molding method using dry blending of powders is vulcanized compared to conventional injection molding and compression molding for elastomers and elastic members. Since there are no processes and the molding load is small, the production process can be greatly simplified. Further, in the case of forming a green compact by sintering, problems such as wear of the mold do not occur as compared with injection molding or compression molding of an elastomer or an elastic member.
When mounting a sintered body to be a multipolar magnet on a cored bar, it can be mounted by a simple clamping process or a mechanical fixing method such as press-fitting, so even under severe conditions in high and low temperature environments. Reliability can be maintained even when exposed.
A magnetic pole is alternately magnetized in the circumferential direction on the sintered body to obtain a multipolar magnet.

  The magnetic encoder is used for rotation detection with a magnetic sensor facing a multipolar magnet. When this magnetic encoder is rotated, the passage of each magnetic pole of the multipolar magnet is detected by the magnetic sensor, and the rotation is detected in the form of pulses. Since the multi-pole magnet is made of a sintered body mixed with magnetic powder, as described above, it can secure a magnetic force with which stable sensing is obtained, and the magnetic encoder can be made compact and has excellent wear resistance. Further, since the metal cored bar and the multipolar magnet can be integrated by an assembling method such as caulking or press fitting, the fixing method is also excellent.

  The magnetic encoder may constitute a part of a seal device that seals an end of a space between an inner ring and an outer ring in a rolling bearing. In this case, the rotation of the bearing can be detected without increasing the number of parts.

  The wheel bearing according to the present invention includes an outer member in which a double-row raceway surface is formed on the inner peripheral surface, an inner member in which a raceway surface opposite to the rolling surface of the outer member is formed on the outer peripheral surface, and these A double-row rolling element interposed between both raceway surfaces, and a wheel bearing for rotatably supporting the wheel with respect to the vehicle body, wherein the rotation-side member of the inner member and the outer member A magnetic encoder is attached, and the magnetic encoder is disposed on the inner side of the end surface of the fixed member in the space between the inner member and the outer member, and the magnetic encoder is a mixed powder of magnetic powder and nonmagnetic metal powder. The magnetic powder and non-magnetic metal powder used for the mixed powder both have an average particle diameter of 10 μm. The above is 150 μm or less.

In general, wheel bearings are exposed to the road surface environment, and particles such as sand particles may be caught between the magnetic encoder and the magnetic sensor that faces the magnetic encoder. Protected like.
That is, the surface hardness of the sintered multipolar magnet made of magnetic powder and nonmagnetic metal powder is harder than that of a conventional elastic member or elastomer coder containing magnetic powder or magnetic particles. For this reason, in a wheel bearing having a magnetic encoder for detecting wheel rotation, particles such as sand particles get caught in the gap between the surface of the rotating multipolar magnet and the surface of the stationary magnetic sensor during vehicle running. Even if rare, it has a significant reduction effect on wear damage of multipolar magnets.

A bearing with a magnetic encoder according to the present invention is a rolling bearing in which a rolling element is interposed between raceways facing an inner ring and an outer ring, and a magnetic encoder is attached to a rotating side wheel of the inner ring and the outer ring. Arranged on the inner side of the end face of the fixed side ring in the space between the inner ring and the outer ring, the magnetic encoder is composed of a sintered body obtained by sintering a mixed powder of magnetic powder and nonmagnetic metal powder, and is alternately arranged in the circumferential direction. The magnetic powder and non-magnetic metal powder used in the above mixed powder each have an average particle diameter of 10 μm or more and 150 μm or less, so that the magnetic force that enables stable sensing is obtained. Can be secured, and it is solid and has excellent wear resistance. Further, it is easy to form a green compact having a predetermined shape in the manufacturing process of the multipolar magnet, the green compact strength can be secured, and the productivity is excellent.
The wheel bearing according to the present invention is a wheel bearing in which a double row rolling element is interposed between the raceway surfaces of the outer member and the inner member facing each other, and the rotation of the inner member and the outer member is performed. A magnetic encoder is attached to the side member, and the magnetic encoder is disposed on the inner side of the end surface of the fixed side member in the space between the inner member and the outer member. The magnetic encoder includes magnetic powder and non-magnetic metal powder. The magnetic powder and non-magnetic metal powder used in the mixed powder are both average grains. Since the diameter is 10 μm or more and 150 μm or less, a compact configuration can improve the reliability and reliability of sensing for detecting rotation, and a green compact with a predetermined shape can be formed during the manufacturing process of multipolar magnets. Easy to secure green compact strength and excellent productivity It is.

  A wheel bearing which is a magnetic encoder according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the wheel bearing includes an inner member 1 and an outer member 2, a plurality of rolling elements 3 accommodated between the inner and outer members 1 and 2, and the inner and outer members 1 and 2. Sealing devices 5 and 13 for sealing the end annular space. The sealing device 5 at one end is provided with a magnetic encoder 10. The inner member 1 and the outer member 2 have raceway surfaces 1a and 2a of the rolling element 3, and each raceway surface 1a and 2a is formed in a groove shape. The inner member 1 and the outer member 2 are an inner peripheral member and an outer peripheral member that are rotatable with respect to each other via the rolling elements 3, respectively. An assembly member in which the bearing inner ring and the bearing outer ring are combined with another component may be used. Further, the inner member 1 may be a shaft. The rolling element 3 consists of a ball or a roller, and a ball is used in this example.

  This wheel bearing is a double-row rolling bearing, more specifically, a double-row angular contact ball bearing, and the inner ring of the bearing is a pair of split type in which the raceway surfaces 1a and 1a of the respective rolling element rows are respectively formed. It consists of inner rings 18 and 19. The inner rings 18 and 19 are fitted to the outer periphery of the shaft portion of the hub ring 6 and constitute the inner member 1 together with the hub ring 6. The inner member 1 is integrated with the hub ring 6 and one inner ring 18 instead of the three-piece assembly part including the hub ring 6 and the pair of split inner rings 18 and 19 as described above. It is good also as what consists of two components comprised by the hub ring with a raceway surface and the other inner ring | wheel 19. FIG.

One end (for example, an outer ring) of the constant velocity universal joint 7 is connected to the hub wheel 6, and a wheel (not shown) is attached to the flange portion 6 a of the hub wheel 6 with a bolt 8. The other end (for example, inner ring) of the constant velocity universal joint 7 is connected to the drive shaft.
The outer member 2 includes a bearing outer ring, and is attached to a housing (not shown) including a knuckle or the like in the suspension device. The rolling elements 3 are held by a holder 4 for each row.

  FIG. 2 shows an enlarged view of the sealing device 5 with a magnetic encoder. The sealing device 5 is attached to a rotating member of the inner member 1 and the outer member 2 with the magnetic encoder 10 or its core 11 serving as a slinger. In this example, since the member on the rotation side is the inner member 1, the magnetic encoder 10 is attached to the inner member 1. Further, the magnetic encoder 10 is inside the end surface 2k of the outer member 2 which is a fixed side member of the outer member 2 and the inner member 1, and is in a space between the outer member 2 and the inner member 1. Has been placed. In this embodiment, the magnetic encoder 10 is entirely composed of the raceway surfaces 1a and 2a in the space between the inner member 1 and the outer member 2, and the end surfaces 1k and 2k of the inner member 1 and the outer member 2. Is housed in between.

This sealing device 5 has annular sealing plates (11), 12 made of first and second metal plates attached to the inner member 1 and the outer member 2, respectively. The first seal plate (11) is the core metal 11 in the magnetic encoder 10 and will be described as the core metal 11 below.
The magnetic encoder 10, which will be described later with reference to FIGS. 3 to 5, includes a multipolar magnet 14 in which magnetic poles are alternately formed in the circumferential direction. The rotation detection device 20 for detecting the wheel rotation speed is configured by arranging the magnetic sensor 15 as shown in the figure so as to face the multipolar magnet 14 in the magnetic encoder 10.

The second seal plate 12 is a member constituting the seal member 9 (FIG. 5), and slides on the side lip 16a and the cylindrical portion 11a that are in sliding contact with the upright plate portion 11b of the core metal 11 that is the first seal plate. Radial lips 16b and 16c that are in contact with each other are integrally provided. The lips 16 a to 16 c are provided as a part of the elastic member 16 that is vulcanized and bonded to the second seal plate 12. The number of the lips 16a to 16c may be arbitrary, but in the example of FIG. 2, one side lip 16a and two radial lips 16c and 16b positioned inside and outside in the axial direction are provided. The second seal plate 12 is configured such that an elastic member 16 is held in a fitting portion with the outer member 2 that is a fixed side member. That is, the elastic member 16 has a tip cover portion 16d that covers from the inner diameter surface of the cylindrical portion 12a to the outer diameter of the tip portion, and this tip cover portion 16d is formed between the second seal plate 12 and the outer member 2. Intervenes in the fitting part.
The cylindrical portion 12a of the second seal plate 12 and the other cylinder portion 11c of the core metal 11 that is the first seal plate are opposed to each other with a slight radial gap, and the labyrinth seal 17 is configured by the gap.

According to the wheel bearing of this configuration, the rotation of the inner member 1 rotating together with the wheel is detected by the magnetic sensor 15 via the magnetic encoder 10 attached to the inner member 1, and the wheel rotation speed is detected. The
Since the magnetic encoder 10 is a constituent element of the sealing device 5, the rotation of the wheel can be detected without increasing the number of parts. The wheel bearing is generally exposed to a road surface environment, and particles such as sand particles may be caught between the magnetic encoder 10 and the magnetic sensor 15 facing the magnetic encoder 10 as described above. Since the ten multipolar magnets 14 are made of a sintered body and are hard, wear damage on the surface of the multipolar magnets 14 is greatly reduced as compared with a conventional elastic body. Further, the space at the bearing end portion of the wheel bearing 5 is a narrow space limited by the constant velocity joint 7 and the bearing support member (not shown) in the periphery, but the multipolar magnet 14 of the magnetic encoder 10 is the above-described space. Therefore, the rotation detector 20 can be easily arranged.
As for the seal between the inner and outer members 1 and 2, the first seal plate is used for sliding contact of the seal lips 16 a to 16 c provided on the second seal plate 12 and the cylindrical portion 12 a of the second seal plate 12. It is obtained with the labyrinth seal 17 configured by the other cylindrical portion 11c of a certain core metal 11 facing each other with a slight radial gap.

  A specific example of the magnetic encoder 10 will be described with reference to FIGS. The magnetic encoder 10 includes a metal annular cored bar 11 and a multipolar magnet 14 provided on the surface of the cored bar 11 along the circumferential direction. The multipolar magnet 14 is a member that is magnetized in multiple poles in the circumferential direction and has magnetic poles N and S alternately formed, and is composed of a magnetic disk magnetized in multiple poles. The magnetic poles N and S are formed to have a predetermined pitch p in the pitch circle diameter PCD (FIG. 4). This magnetic encoder 10 is attached to a rotating member (not shown), and is used for rotation detection with a magnetic sensor 15 facing a multipolar magnet 14 as shown in FIGS. 10 and the magnetic sensor 15 constitute a rotation detection device 20. This figure shows an application example in which the magnetic encoder 10 is a component of a seal device 5 for a bearing (not shown), and the magnetic encoder 10 is attached to a bearing ring on the rotation side of the bearing. The seal device 5 includes a magnetic encoder 10 and a fixed-side seal member 9.

  The magnetic powder mixed in the multipolar magnet 14 may be isotropic or anisotropic ferrite powder such as barium-based and strontium-based. These ferrite powders may be granular powders or pulverized powders composed of a wet anisotropic ferrite core. When the pulverized powder made of this wet anisotropic ferrite core is used as a magnetic powder, it is necessary to use a mixed powder with a nonmagnetic metal powder as an anisotropic green body formed in a magnetic field.

  The magnetic powder may be a rare earth magnetic material. For example, samarium iron (SmFeN) magnetic powder and neodymium iron (NdFeB) magnetic powder, which are rare earth magnetic materials, may be used alone. The magnetic powder may be manganese aluminum (MnAl) gas atomized powder.

The magnetic powder may be a mixture of two or more of samarium iron (SmFeN) magnetic powder, neodymium iron (NdFeB) magnetic powder, and manganese aluminum (MnAl) gas atomized powder. For example, the magnetic powder is a mixture of samarium iron (SmFeN) magnetic powder and neodymium iron (NdFeB) magnetic powder, a mixture of manganese aluminum gas atomized powder and samarium iron magnetic powder, and samarium iron. Any of a mixture of a system magnetic powder, a neodymium iron system magnetic powder, and a manganese aluminum gas atomized powder may be used.
Also, for example, when the magnetic force is insufficient with only the ferrite content, the required amount of samarium iron (SmFeN) magnetic powder or neodymium iron (NdFeB) magnetic powder, which is a rare earth magnetic material, is mixed with the ferrite powder to improve the magnetic force. It can also be manufactured at a low cost.

  In addition, the nonmagnetic metal powder forming the multipolar magnet 14 may be any one of powders of tin, copper, aluminum, nickel, zinc, tungsten, manganese, etc., or nonmagnetic stainless steel metal powder alone (one type). These powders, mixed powders of two or more, or alloy powders of two or more can be used.

Both the magnetic powder and the nonmagnetic metal powder have an average particle size of 10 μm to 150 μm, preferably 20 μm to 130 μm. If the average particle size of one or both of these powders is smaller than 10 μm, even if you try to obtain a green compact by pressing it in a mold at room temperature to make a mixed powder, it will mix well in the mold Powder may not flow in, and a green compact with a predetermined shape cannot be formed. In addition, if the average particle size of one or both of these powders is larger than 150 μm, even if an attempt is made to obtain a green compact by pressing it in a mold at room temperature as a mixed powder, the green compact strength Therefore, it cannot be removed from the mold and cannot be molded.
The above-mentioned average particle size range magnetic powder and non-magnetic metal powder are mixed at a predetermined mixing ratio using a powder mixer, and the mixed powder is pressed in a mold at room temperature. Obtain powder.

In the blending in the mixed powder forming the multipolar magnet 14, the volume blending ratio of the non-magnetic metal powder that is not magnetic powder is preferably 1 vol% or more and 90 vol% or less, preferably 5 vol% or more and 85 vol% or less, and more desirably 10 vol% or more and 80 vol% or less are good.
When the volume content of the nonmagnetic metal powder that is not magnetic powder is less than 1 vol%, the nonmagnetic metal powder is small as a metal binder, so that the multipolar magnet 14 obtained after sintering is hard but brittle. For this reason, as will be described later, even if the sintered body to be the multipolar magnet 14 is mechanically fixed on the core metal 11 by caulking or press-fitting, it is cracked. Moreover, since there are too few metal binders, a green compact may not be shape | molded.
If the volume content of the nonmagnetic metal powder that is not magnetic powder is more than 90 vol%, the magnetic component is relatively small, so that the magnetization strength of the obtained multipolar magnet 14 cannot be increased after sintering, and the magnetic encoder 10 Therefore, it is not possible to secure the magnetic force for obtaining the desired stable sensing.

The linear expansion coefficient of the multipolar magnet 14 obtained after sintering is preferably 0.5 × 10 ⁻⁵ or more and 9.0 × 10 ⁻⁵ or less, but preferably 0.8 × 10 ⁻⁵ or more and 7 × 10 ⁻⁵ or less, more preferably 0.9 × 10 ⁻⁵ or more and 5 × 10 ⁻⁵ or less.
For example, in the case of stainless steel (JIS standard SUS430), the linear expansion coefficient of the metal material used as the material of the core metal 11 is 1.0 × 10 ⁻⁵ . When the linear expansion coefficient of the multipolar magnet 14 is larger than 0.5 × 10 ⁻⁵ or smaller than 9 × 10 ⁻⁵ , the difference in linear expansion coefficient from the metal material that is the material of the core metal 11 is large. The difference in dimensional change when used in a high and low temperature environment becomes large, and the multipolar magnet 14 and the core metal 11 may interfere with each other and the multipolar magnet 14 may be damaged. Further, it becomes impossible to secure the multipolar magnet 14 and the cored bar 11.

In forming the green compact, a lubricant such as zinc stearate may be added to improve the green compact moldability when the magnetic powder and the nonmagnetic metal powder are blended.
These green compacts (green bodies) desirably have 5 to 30 vol% pores. Preferably it is 12-22 vol%, More preferably, it is 14-19 vol%. When the porosity is less than 5 vol%, the green compact may be damaged due to springback caused by recovery of elastic deformation of the raw material powder when the molding pressure is released. In addition, when the number of pores is more than 30 vol%, the mechanical strength of the sintered body is weakened, and as described later, even if it is attempted to be mechanically fixed on the core metal 11 by caulking or press fitting, etc. End up. In addition, the green compact may not be formed due to insufficient adhesion between the particles.

Since magnetic powder and non-magnetic metal powder are expensive, it is preferable that the plate thickness is thin. In view of compression moldability and handling, the preferred plate thickness is 0.3 mm to 5 mm, more preferably 0.6 mm to 3 mm. When the plate thickness is less than 0.3 mm, it is difficult to fill the mold and it is difficult to obtain a green molded body. Moreover, since the obtained green molded object may also be damaged at the time of handling, it is not preferable. On the other hand, when the green molded body is thicker than 10 mm, the moldability and handling are improved, but it is disadvantageous in terms of cost. On the other hand, when the thickness is too thick, uneven density of the green molded body tends to occur, and deformation after firing tends to occur. From these points, the plate thickness is preferably 0.3 mm to 5 mm.
The obtained green molded body is heated and sintered in a furnace as shown in FIG. 6 to form a disk-shaped sintered body. The heating and sintering in the furnace may be performed in an electric furnace in the atmosphere, or may be performed in a pusher furnace or an inert furnace while flowing an inert gas in a vacuum furnace.

The sintered body forming the magnetic encoder 10 may be provided with a rust preventive coating 22 as shown in FIG. In other words, the rust preventive film 22 is an anticorrosive film. The rust-proof coating 22 can be a clear high anti-corrosion paint. This paint can also be expected to have an effect as an adhesive between the core metal 11 and the sintered body, and penetrates into the pores of the surface layer of the sintered porous body and is suitably held on the surface by the anchor effect of the clear coating film component. Even during long-term use, good adhesion can be maintained as a rust-proof coating layer.
Examples of clear anticorrosive paints include modified epoxy paints, modified epoxy phenol curable paints, epoxy melamine paints, and acrylic paints. Among these, a modified epoxy phenol curing type and epoxy melamine type clear coating are particularly suitable.
Also, apply the clear to vacuum or impregnation (dipping), spray (spray) coating, electrostatic coating, etc. on fat or washed sintered body, and adhere to the sintered body by natural or forced air drying. The solvent component in the clear is removed, and the clear layer is baked on the sintered body under predetermined baking conditions (temperature and time), so that the anticorrosive coating 22 is applied to the surface of the multipolar magnet 14 as shown in FIG. May be formed. The rust preventive coating 22 may be formed on the entire surface of the magnetic encoder 10. When this magnetic encoder 10 is attached to, for example, a wheel bearing, the film thickness of the anticorrosion (corrosion) film formed as described above is not particularly limited as long as it can satisfy the corrosion resistance required for the wheel bearing. However, 0.5 μm or more is desirable.
When used as a wheel bearing, if sand particles or the like are caught in the gap between the magnetic sensor 15 and the surface of the magnetic encoder 10, the surface of the magnetic encoder 10 may be damaged. If the thickness of the coating is thinner than 0.5 μm, the scratches may reach the sintered body as the base material, and the generation of rust from there may not be prevented.

  The metal that is the material of the core metal 11 is preferably a magnetic material, particularly a metal that is a ferromagnetic material. For example, a steel plate that is magnetic and has rust prevention properties is used. As such a steel plate, a ferritic stainless steel plate (JIS standard SUS430 series or the like), a rust-proof rolled steel plate, or the like can be used.

The shape of the core metal 11 can be various annular shapes, but a shape capable of fixing the multipolar magnet 14 is preferable. In particular, a shape capable of performing mechanical fixing such as caulking and fitting fixing is preferable.
In the case of caulking and fixing, for example, as shown in FIG. 3 (B), the core 11 includes a cylindrical portion 11a on the inner diameter side serving as a fitting side, a standing plate portion 11b extending from one end to the outer diameter side, The cross section formed by the other cylindrical portion 11c of the radial edge has a generally inverted Z-shaped annular shape.
The cylindrical portion 11a, the upright plate portion 11b, and the other cylindrical portion 11c are integrally formed by pressing from a metal plate such as a steel plate. The standing plate portion 11b is formed flat, and a non-magnetized sintered body of the multipolar magnet 14 is built on the surface of the flat standing plate portion 11b, and the other cylindrical portion 11c of the outer peripheral edge is crimped. Thus, the multipolar magnet 14 is fixed in an overlapping state with the standing plate portion 11 b of the core metal 11. The other cylindrical portion 11c has a crimped portion at the front end side portion or substantially the whole in its cross section. Further, this caulking portion extends over the entire circumference of the core metal 11 and thus has an annular shape. The portion fixed by the other cylindrical portion 11 c that is the crimping portion of the multipolar magnet 14 is a recessed portion 14 a that is recessed from the surface to be detected of the multipolar magnet 14, and the crimping portion of the core metal 11. The other cylindrical portion 11c is configured not to protrude from the surface to be detected of the multipolar magnet 14. The recessed portion 14 a is formed as a stepped portion that is slightly retracted to the back side from the surface to be detected of the multipolar magnet 14. A portion of the outer peripheral edge of the multipolar magnet 14 on the back side with respect to the recessed portion 14a is a curved surface having a circular cross section, and a crimped portion of the other cylindrical portion 11c is formed along the curved surface portion. As shown in the sectional view of FIG. 7, the caulking and fixing may be performed by caulking and fixing the outer peripheral portion of the multipolar magnet 14 over the entire circumference.

  Further, the caulking and fixing may be performed as shown in the sectional view and the front view in FIGS. In this example, the cored bar 11 has a cylindrical portion 11a on the inner diameter side, a standing plate portion 11b extending from one end to the outer diameter side, and a cylindrical other cylindrical portion 11c on the outer diameter edge, as in the example of FIG. The cross section is generally an inverted Z-shaped ring. In addition, a plastic deformation portion 11ca that is plastically deformed in a protruding state toward the inner diameter side by staking or the like is provided at a plurality of locations in the circumferential direction of the cylindrical portion 11c, and the multipolar magnet 14 is placed upright on the core metal 11 by the plastic deformation portion 11ca. It is fixed to the plate part 11b. Also in this example, the portion fixed by the plastic deformation portion 11ca of the multipolar magnet 14 is a dent portion 14b that is recessed from the surface of the multipolar magnet 14 that becomes the detection surface, whereby the plastic deformation portion 11ca is The multipolar magnet 14 is configured not to protrude from the surface to be detected. The recessed portion 14b is an inclined surface 14b that approaches the rear surface side from the front surface toward the outer diameter side.

In each example shown in FIG. 5 and FIG. 8, the cored bar 11 has a stepped shape in which the upright plate portion 11b is displaced in the axial direction between the inner peripheral portion 11ba and the outer peripheral portion 11bb as shown in FIG. It can also be made. In FIG. 10, although not shown, the multipolar magnet 14 is disposed on the surface of the upright plate portion 11b on the protruding side of the other cylindrical portion 11c as in the example of FIG.
Furthermore, as shown in FIG. 11, in the metal core 11 having a substantially inverted Z-shaped cross section as in the above examples, the tongue-like claw portions 11cb are provided at a plurality of locations in the circumferential direction at the edge of the other cylindrical portion 11c. The multi-pole magnet 14 may be fixed to the core metal 11 by plastically deforming the tongue-like claw portion 11cb toward the inner diameter side as shown by an arrow, that is, by crimping. The multipolar magnet 14 is disposed on the surface of the upright plate portion 11b on the protruding side of the other cylindrical portion 11c as in the example of FIG. Also in this example, like the example of FIG. 10, the standing board part 11b is made into the stepped shape. When the standing plate portion 11b is stepped, the side surface shape of the multipole magnet 14 on the standing plate portion 11b side is a side shape along the stepped shape of the standing plate portion 11b as shown in FIG. Also good.

  In the case of press-fitting and fixing, for example, as shown in FIG. 12, the cored bar 11 is a circle having an L-shaped cross section comprising a cylindrical portion 11a on the inner diameter side and a standing plate portion 11b ″ extending from one end to the outer diameter side The cylindrical portion 11a and the upright plate portion 11b ″ are integrally formed by pressing from a metal plate such as a steel plate. The upright plate portion 11b ″ is formed flat, and a disk-like sintered body that becomes the multipolar magnet 14 is press-fitted and fixed to the outer periphery of the cylindrical portion 11a up to the flat upright plate portion 11b ″. The height of the upright plate portion 11 b ″ is set so that the vicinity of the inner peripheral portion of the multipolar magnet 14 hits.

  In each of the above examples, the metal core 11 is made of a steel plate press-formed product. However, as shown in FIG. 13, the metal core 11 may be made of a machined product such as a steel material. The cored bar 11 in the example of the figure has the groove 11ba of the standing plate 11b as a cutting groove.

  The mixed magnetic powder sintered magnet disk provided along the circumferential direction on the metal core 11 that is a metal annular member as described above becomes a multipolar magnet 14 by being magnetized in multiple directions in the circumferential direction. The magnet 14 and the cored bar 11 constitute a magnetic encoder 10. In this case, the mixed magnetic powder sintered magnet disk (sintered body) mixed with magnetic powder using nonmagnetic metal powder as a binder is adjusted with a powder mixer while adjusting the composition ratio of the nonmagnetic metal powder and magnetic powder. By dispersing, a dry blend of powders can be obtained. Therefore, the relative content rate (volume fraction) of the magnetic powder in the sintered body can be increased. Therefore, the magnetic force stably sensed by the magnetic sensor 15 (FIG. 5) can be easily obtained, and it is not necessary to make the multipolar magnet 14 thick.

As described above with reference to FIGS. 2 and 5, the magnetic encoder 10 having this configuration is used for rotation detection with the magnetic sensor 15 facing the multipolar magnet 14. When the magnetic encoder 10 is rotated, the magnetic sensor 15 detects the passage of the magnetic poles N and S magnetized in the multipole of the multipolar magnet 14, and the rotation is detected in the form of pulses. The pitch p (FIG. 4) of the magnetic poles N and S can be set finely. For example, it is possible to obtain an accuracy that the pitch p is 1.5 mm and the pitch difference is ± 3%, thereby enabling highly accurate rotation detection. The pitch mutual difference is a value indicating a difference in distance between the magnetic poles detected at a position away from the magnetic encoder 10 by a predetermined distance as a ratio to the target pitch. When the magnetic encoder 10 is applied to the bearing seal device 5 as shown in FIG. 5, the rotation of the bearing to which the magnetic encoder 10 is attached is detected.
Since the multi-pole magnet 14 is made of a sintered body (mixed magnetic powder sintered disk) mixed with magnetic powder, the magnetic pole can be thinned while securing a magnetic force to obtain stable sensing as shown below. 10 can be made compact, and it is excellent in wear resistance and productivity.

Furthermore, the surface hardness of the multipolar magnet 14 is harder than that of an elastic member or elastomer coder containing conventional magnetic powder or magnetic particles. For this reason, when applied to the rotation detection device 20 for detecting wheel rotation, particles such as sand particles bite into the gap between the surface of the rotation-side multipolar magnet 14 and the surface of the stationary-side magnetic sensor 15 during vehicle travel. Even if it is inserted, wear damage of the multipolar magnet 14 hardly occurs, and there is a significant reduction effect of wear as compared with a conventional elastic body.
The flatness of the surface of the mixed magnetic powder sintered magnet disk that becomes the multipolar magnet 14 provided along the circumferential direction on the metal core 11 that is a metal annular member is preferably 200 μm or less, and preferably 100 μm or less. . When the flatness of the disk surface is higher than 200 μm, the gap between the magnetic sensor 15 and the disk surface (air gap) changes during the rotation of the magnetic encoder 10, thereby degrading the sensing accuracy.
For the same reason, the surface runout of the mixed magnetic powder sintered magnet disk surface during rotation of the magnetic encoder 10 is preferably 200 μm or less, and preferably 100 μm or less.

In the wheel bearing shown in FIGS. 1 and 2, the core 11 of the magnetic encoder 10 is shown as having the shape shown in FIG. 3, but the magnetic encoder 10 is shown in FIGS. 8 to 13. Each example may be used.
Further, when the magnetic encoder 10 is used as a component of the bearing seal device 5, the multipolar magnet 14 may be provided inward with respect to the bearing, contrary to the above embodiments. That is, the multipolar magnet 14 may be provided on the inner surface of the bearing of the core metal 11. In that case, the cored bar 11 is preferably made of a non-magnetic material.

Furthermore, the magnetic encoder of the present invention may employ any of the following structures (1) to (6) as a structure for fixing the multipolar magnet to the core metal. These structures (1) to (6) are rearranged from a viewpoint different from the above explanations.
(1). In the metal core, a press-fitting portion that is press-fitted into a rotation-side member (for example, a rotating wheel of a rolling bearing) and a portion to which a multipolar magnet is attached are separated from each other. (For example, the example of FIG. 3)
(2). In the above (1), the multipolar magnet is fixed to the cored bar by a crimped portion in which the cored bar is crimped. In this case, the multipolar magnet is overlapped with a part of the core metal, and one end of the multipolar magnet in the cross section is formed by caulking the core metal. (For example, the example of FIG. 3)
(3). In the above (2), the crimping portion of the core metal is divided into a plurality of locations in the circumferential direction. (For example, the example of FIG. 8)
(Four) . In the above (2), the portion fixed by the crimping portion of the core of the multipolar magnet is a recess that is recessed from the surface to be detected of the multipolar magnet, and the crimping portion of the core is not It is assumed that the multipolar magnet does not protrude from the surface to be detected. The said recessed part consists of an inclined surface or a level | step difference surface inclined with respect to the surface used as the said to-be-detected surface, for example. (For example, the example of FIG. 3)
(Five) . In the above (2), the surface of the cored bar in contact with the multipolar magnet has a thinned portion.
(6). (2) In the above (2), the magnetic encoder is an arc-shaped or annular portion in which the caulking portion of the core bar extends in the circumferential direction.This magnetic encoder has various multi-poles having novel features such as (1) to (6) A magnet mounting structure can be made possible, and therefore, the application range is wide, high reliability can be imparted, and it can be said that it is very excellent.

It is sectional drawing of the bearing with a magnetic encoder concerning one Embodiment of this invention. It is a fragmentary sectional view of the bearing for the wheels. (A) is a fragmentary perspective view of the magnetic encoder used for the bearing with a magnetic encoder of the embodiment, (B) is a fragmentary perspective view showing the assembly process of the magnetic encoder. It is explanatory drawing of the magnetic pole which shows the same magnetic encoder from the front. It is a partial fracture front view showing a sealing device provided with the magnetic encoder and a magnetic sensor. It is process drawing which uses a green body as a sintered compact. It is a fragmentary perspective view of the modification of a magnetic encoder. It is a fragmentary perspective view of the other modification of a magnetic encoder. It is a front view of the magnetic encoder. It is a fragmentary sectional view of the modification of a metal core. (A), (B) is another partial perspective view of the other modification of a metal core, and the magnetic encoder using the metal core, respectively. It is a fragmentary perspective view of other modification of a magnetic encoder. It is a fragmentary perspective view of other modification of a magnetic encoder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inner member 2 ... Outer member 1A ... Inner member 2A ... Outer member 1k, 2k ... End surface 3 ... Rolling body 5 ... Sealing device 10 ... Magnetic encoder 15 ... Magnetic sensor 16a ... Side lip 16b, 16c ... Radial Lip 20 ... Rotation detection device

Claims (4)

In a rolling bearing in which a rolling element is interposed between raceways facing the inner ring and the outer ring, a magnetic encoder is attached to a rotating side wheel of the inner ring and the outer ring, and the magnetic encoder is fixed in a space between the inner ring and the outer ring. The magnetic encoder is arranged on the inner side of the end face of the side wheel, and the multipolar magnet is assembled to a metal core by caulking or press-fitting and supported by the core. is poles alternately in the circumferential direction becomes a mixed powder of a magnetic powder and a nonmagnetic metal powder of a sintered body of porous and sintered is formed, a magnetic powder and a nonmagnetic metal for use in the above mixed powder Each of the powders has an average particle size of 10 μm or more and 150 μm or less, the linear expansion coefficient of the multipolar magnet is 0.5 × 10 ⁻⁵ or more and 9.0 × 10 ⁻⁵ or less, A magnetic element characterized in that the green compact before sintering has pores inside. Over da with the bearing. The bearing with a magnetic encoder according to claim 1 , wherein the cored bar is made of stainless steel. 3. The bearing with a magnetic encoder according to claim 1 , wherein the magnetic encoder constitutes a part of a seal device that seals an end of a space between an inner ring and an outer ring in a rolling bearing. An outer member having a double-row raceway surface formed on the inner circumferential surface, an inner member having a raceway surface opposite to the rolling surface of the outer member formed on the outer circumferential surface, and interposed between both raceway surfaces A wheel bearing comprising a double row rolling element and rotatably supporting the wheel with respect to the vehicle body,
Mounting a magnetic encoder to the rotating side member of said inner member and the outer member, the magnetic encoder is disposed on the inner side of the end face of the stationary member in the space between the inner member and the outer member, the The magnetic encoder is a multi-pole magnet assembled to a metal core by caulking or press-fitting and supported by the core, and the multi-pole magnet is a mixture of magnetic powder and non-magnetic metal powder. in magnetic poles alternately in the circumferential direction becomes a powder of a sintered body of porous and sintered is formed, the magnetic powder and non-magnetic metallic powder used in the powder mixture, both the average particle diameter of 10μm or more 150 μm or less, the linear expansion coefficient of the multipolar magnet is 0.5 × 10 ⁻⁵ or more and 9.0 × 10 ⁻⁵ or less, and the green compact before sintering of the mixed powder contains voids therein. Wheel bearings characterized by having.

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