JP2006194642A - Magnetic encoder and bearing for wheel equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably fix a multipole magnet, especially a multi-pole magnet made of a sintered body, to an arbor in a magnetic encoder at low costs. <P>SOLUTION: The arbor 11 is constituted of a cylindrical mounting part 12a to be mounted on a member on the rotating side; a contact part 12b extended from one end of the mounting part 12a to its outer diameter side into contact with a face of a sintered body (a multipole magnet 14); and a fixing part 13 arranged on the side opposite to the mounting part 12a in an outer-diameter end of the contact part 12b for holding and fixing the multipole magnet 14 from both sides. The fixing part 13 is provided with a holding surface 13a for holding an outer peripheral part 14a of the multipole magnet 14 from both sides in its inner circumference. The outer peripheral surface 14b of the disk-like multipole magnet 14 has such a planar shape as to follow the holding surface 13a of the fixing part 13. With a compressed and molded body 14' to be expanded after sintering in contact with the contact part 12b of the arbor 11, the compressed and molded body 14' is sintered. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetic encoder and a wheel bearing provided with the magnetic encoder, and is used, for example, in a rotation detection device that detects the number of rotations of a wheel in an antilock brake system of an automobile.

  There are roughly two types of this type of rotation detection device: a passive type that reads the movement of the uneven teeth provided on the rotor as the magnitude of the magnetic change, and the strength of the magnetism associated with the rotation of the magnetic encoder. An active type that reads changes with a magnetic sensor such as a Hall IC is used.

  In an active type rotation detection device, a magnetic encoder is usually provided on the rotation side member of the wheel bearing, and a magnetic sensor is provided on the fixed side member.

The magnetic encoder includes, for example, an annular multipolar magnet in which N poles and S poles are alternately magnetized in the circumferential direction, and a core bar for fixing the multipolar magnet to the rotation side member. As a multipolar magnet, there are those made of an elastomer to which magnetic powder is added, and recently, as a multipolar magnet, a mixture of magnetic powder and nonmagnetic metal powder is compression-molded and then sintered. A multipolar magnet made of a sintered body is fixed to a predetermined position of a core metal by, for example, caulking or press-fitting (see, for example, Patent Document 1).
JP 2004-37441 A

  The multipolar magnet made of the sintered body is very preferable as a product because it has the advantages of excellent wear resistance and low processing cost compared to the elastomer type multipolar magnet. However, a magnet made of a sintered body is very fragile, and the amount of caulking tends to vary when fixed by caulking. Therefore, cracks may occur depending on the degree of caulking. If the amount of caulking is adjusted with high accuracy, it is possible to suppress cracking of the sintered body, but higher accuracy of caulking processing results in higher costs.

  An object of the present invention is to fix a multipolar magnet in this type of magnetic encoder, in particular, a multipolar magnet made of a sintered body, to a core metal reliably and at low cost.

  In order to solve the above problems, a magnetic encoder according to the present invention includes a multipolar magnet formed by compressing and molding a mixed powder of magnetic powder and nonmagnetic metal powder, and a core bar to which the multipolar magnet is fixed. The cored bar includes a fixing portion for fixing the multipolar magnet, and the multipolar magnet is sandwiched and fixed to the fixing portion by expansion after sintering.

  When metal powder is sintered, the volume of the sintered body often increases (expands) or decreases (shrinks) before and after sintering. This type of behavior varies depending on the type and combination of powders used. The present invention has been conceived by paying attention to this point, and is characterized in that it is clamped and fixed to a metal core by utilizing expansion after sintering of a multipolar magnet (sintered body). . Since the cored bar is usually formed by pressing, cutting, etc., it is relatively difficult to process the dimension of the cored bar with a predetermined accuracy in consideration of the expansion amount after sintering of the multipolar magnet. Easy. Therefore, according to this fixing method, it is possible to adjust the load on the sintered body at the time of fixing with the dimensional accuracy of the cored bar formed by, for example, press working or the like without fixing by caulking. Therefore, high-precision fixing can be performed at low cost compared to fixing by caulking, in which the caulking amount tends to vary. Moreover, according to the said structure, since a multipolar magnet can be sintered and fixed to a metal core simultaneously, a work process is simplified and it becomes possible to further reduce this cost.

  For example, the fixed portion may be configured to include a clamping surface that clamps the outer peripheral portion of the multipolar magnet. According to this, the outer peripheral portion of the multipolar magnet is clamped by expansion after sintering of the multipolar magnet itself. Sandwiched between the faces.

  The said clamping surface is provided in the inner periphery of a fixing | fixed part, for example, and can take various surface shapes. For example, depending on the shape of the clamping surface, such as a cross-sectional arc shape or a U-shaped cross-section, the outer peripheral portion of the multipolar magnet can be clamped in the radial direction and also in the axial direction. In this case, the sandwiching surface also serves to prevent the multipolar magnet from being pulled out in the axial direction.

  As described above, various materials can be used for the magnetic powder and the nonmagnetic metal powder constituting the sintered body to be a multipolar magnet as long as the sintered body expands after sintering. . For example, samarium iron (SmFeN) based magnetic powder can be preferably used as the magnetic powder, and tin, tin-zinc alloy, or a mixed powder of tin and copper can be preferably used as the nonmagnetic metal powder.

  The magnetic encoder having the above configuration can be suitably used by being incorporated in a wheel bearing, for example.

  As described above, according to the present invention, the multipolar magnet made of a sintered body of this type of magnetic encoder can be fixed to the core metal reliably and at low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the magnetic encoder 10 includes an 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 has a disk shape and is magnetized in multiple poles in the circumferential direction, whereby magnetic poles N and S are alternately formed. For example, as shown in FIG. 2, the magnetic poles N and S are formed to have a predetermined pitch p in the pitch circle diameter PCD.

  The multipolar magnet 14 is composed of magnetic powder and nonmagnetic metal powder. Examples of magnetic powders include isotropic or anisotropic ferrite powders such as barium and strontium, samarium iron (SmFeN) magnetic powder, neodymium iron (NdFeB) magnetic powder, and manganese aluminum (MnAl) gas atomized powder. Rare earth magnetic powders such as can be used. In this embodiment, samarium iron (SmFeN) magnetic powder exhibiting ferromagnetism is used among the above magnetic powders.

  As the non-magnetic metal powder, for example, metal powder such as tin, copper, aluminum, nickel, zinc, tungsten, manganese, a powder obtained by mixing two or more of these, or two or more alloy powders can be used. In this embodiment, tin powder having a relatively low melting point is used among the nonmagnetic metal powders.

  As the nonmagnetic metal powder, for example, those having a maximum particle size of 63 μm or less are preferably used. In this embodiment, tin powder having a maximum particle size of 45 μm is used.

  In addition, as the tin powder as the nonmagnetic metal powder, those having a non-spherical shape such as a spongy shape, a needle shape, a square shape, a dendritic shape, a fiber shape, a piece shape, an irregular shape, and a teardrop shape are preferably used. The tin powder having such a shape can be formed by, for example, a water atomization method. The water atomization method is a method in which a molten metal is naturally dropped from pores, and a high-pressure water jet is sprayed on the narrow stream to pulverize, and the cooling time is shorter than that of the gas atomization method. Therefore, the cooled and powdered tin powder has a relatively non-spherical shape. As an example, a micrograph of tin powder formed by the gas atomizing method is shown in FIG. 12A, and a micrograph of tin powder formed by the water atomizing method is shown in FIG. From these figures, it can be seen that the tin powder formed by the gas atomization method is relatively spherical, whereas the tin powder formed by the water atomization method has a relatively irregular shape. In addition, the powder which makes non-spherical shapes, such as the said irregular shape, can be obtained also by the oil atomizing method, for example.

  The blending ratio in the mixed powder forming the multipolar magnet 14 is preferably 10-80 wt% of non-magnetic metal powder with respect to 20-90 wt% of magnetic powder, and 40-80 wt% of magnetic powder. %, And those containing 20-60 wt% of nonmagnetic metal powder are more preferred. If the blending ratio of the non-magnetic metal powder is less than 10 wt%, the non-magnetic metal powder does not function sufficiently as a binder for the magnetic powder, so that the multipolar magnet 14 obtained after sintering is hard but brittle. Therefore, cracks may occur when the multipolar magnet 14 is fixed to the cored bar 11. On the other hand, if the blending ratio of the magnetic powder is less than 20 wt%, the magnetizing strength of the multipolar magnet 14 obtained after sintering cannot be increased, and the magnetic force sufficient to satisfy the stable sensing ability desired for the magnetic encoder 10. May not be secured.

  For example, a lubricant such as zinc stearate may be added to the mixed powder of the magnetic powder and the nonmagnetic metal powder (for example, 1 wt% or less) to improve the compression moldability of the mixed powder.

The mixed powder having the above configuration is compression-molded with a predetermined pressure, and for example, a disk-shaped compression-molded body 14 ′ shown in FIG. 3 is formed. The pressing force at the time of compression molding is preferably 6.0 × 10 ³ kgf / cm ² or more. Moreover, it is desirable that the compression molded body 14 ′ after the compression molding has 5 to 30 vol% voids. The porosity is more preferably 12 to 22 vol%, and further preferably 14 to 19 vol%. This is because if the porosity is less than 5 vol%, the compression molded body 14 ′ may be damaged by the spring back generated when the molding pressure is removed. Moreover, it is because there exists a possibility that the mechanical strength of a sintered compact may be insufficient when a porosity exceeds 30 vol%.

  Since magnetic powder and non-magnetic metal powder are expensive, it is desirable that the thickness of the compression molded body 14 ′ be as thin as possible. In consideration of compression moldability and handling properties (easiness of handling including conveyance to assembling to the core metal 11 etc.), the wall thickness is preferably 0.3 mm to 5 mm, and 0.6 mm to 3 mm. More preferably. When the wall thickness is less than 0.3 mm, it is difficult to fill the powder into the molding die and the compression molded body 14 ′ is difficult to mold. Further, the obtained compression molded body 14 ′ is not preferable because it may be damaged during handling. When the thickness of the compression molded body 14 ′ is thicker than 10 mm, the moldability and handling properties are improved, but on the other hand, the cost is increased. On the other hand, if it is too thick, the density of the compression-molded body 14 ′ tends to be non-uniform, and there is a risk of distorted deformation after sintering.

  For example, as shown in FIG. 3, the core metal 11 includes a cylindrical mounting portion 12 a that is fixed to a rotation-side member by press-fitting or the like, and extends from one end of the mounting portion 12 a to the outer diameter side. The abutting portion 12b abuts against the disk end surface of the magnet 14) and the fixing portion 13 which is disposed on the side opposite to the mounting portion 12a on the outer diameter end of the abutting portion 12b and clamps and fixes the multipolar magnet 14. The fixed portion 13 includes a clamping surface 13 a that clamps the outer peripheral portion 14 a of the multipolar magnet 14 on the inner periphery thereof. As shown in FIG. 1, the clamping surface 13a includes a diameter-enlarging surface 13b that expands from the outer diameter end of the abutting portion 12b toward the axially opposite mounting portion 12a side (right side in the drawing), and a diameter-enlarging surface 13b. The cylindrical surface 13c extends from the large diameter end to the right side in the axial direction, and the reduced diameter surface 13d decreases from the end of the cylindrical surface 13c toward the right side in the axial direction. In this embodiment, the enlarged diameter surface 13b and the reduced diameter surface 13d each have a tapered surface shape. Further, the outer peripheral surface 14 b of the multipolar magnet 14 having a disk shape has a surface shape that follows the holding surface 13 a of the fixed portion 13.

  The cored bar 11 provided with the attachment part 12a, the contact part 12b, and the fixing part 13 can be integrally formed by, for example, press working. In that case, the portion of the fixed portion 13 where the cylindrical surface 13c is formed on the inner periphery is press-molded longer than the predetermined axial length by the portion where the reduced diameter surface 13d is formed on the inner periphery, and further reduced. A portion corresponding to the radial surface 13d is plastically deformed and bent toward the inner diameter side, whereby a cylindrical surface 13c and a reduced diameter surface 13d having a predetermined axial width are formed. Of course, the metal core 11 having the above-described shape may be formed by only one press working by devising a press die. Or you may finish the metal core 11 in the said shape by other machinings, such as cutting.

  As a material constituting the metal core 11, a magnetic material, particularly a metal that becomes a ferromagnetic material is preferable. For example, a steel plate that is a magnetic material and has rust prevention properties is used. In this embodiment, for example, a ferritic stainless steel plate (JIS standard SUS430 system) is used.

  A multipolar magnet 14 (compression molded body 14 ′) before sintering is attached to the core metal 11 having the above-described configuration. Specifically, as shown in FIG. 3, the compression molded body 14 ′ is baked in a state where the end surface of the compression molded body 14 ′ is in contact with the contact portion 12 b of the core metal 11 (the position indicated by the alternate long and short dash line in the figure). Conclude. As in this embodiment, when a samarium iron (SmFeN) magnetic powder is used for the magnetic powder constituting the compression molded body 14 'and a tin powder is used for the nonmagnetic metal powder, the compression molded body after sintering is used. The volume of 14 'increases compared to the volume of the compression molded body 14' before sintering. That is, the compression molded body 14 'expands before and after sintering. As a result, the outer peripheral portion 14 a ′ of the compression molded body 14 ′ is clamped by the clamping surface 13 a of the fixed portion 13. In this embodiment, a portion of the outer peripheral surface 14b 'of the compression molded body 14' facing the cylindrical surface 13c is sandwiched in the radial direction by the cylindrical surface 13c of the fixing portion 13. Further, the diameter-enlarging surface 13b and the diameter-reducing surface 13d of the fixed portion 13 sandwich the portions of the outer peripheral surface 14b 'that face the diameter-enlarging surface 13b and the diameter-reducing surface 13d in the axial direction. In this manner, the compression molded body 14 ′ is clamped and fixed to the core metal 11.

  According to this fixing method, the load on the sintered body at the time of fixing can be adjusted with the dimensional accuracy of the cored bar 11 formed by, for example, press working or the like without fixing by caulking. Therefore, it is possible to perform high-precision fixing as compared to fixing by caulking, in which the caulking amount tends to vary. Further, according to the fixing method, since the compression molded body 14 ′ can be sintered and fixed to the cored bar 11 at the same time, the work process can be simplified and the cost can be reduced.

  In addition, the fixing | fixed part 13 of the metal core 11 can take not only said form but another form. FIG. 5 illustrates a case where the holding surface 13a provided on the inner periphery of the fixed portion 13 is configured in a circular arc shape. In this case, the outer peripheral surface 14b of the multipolar magnet 14 to be clamped and fixed has a surface shape that follows the clamping surface 13e having an arcuate cross section. FIG. 6 illustrates the case where the sandwiching surface 13a is formed in a U-shaped cross section. In FIG. 6, the outer circumferential surface 14b of the multipolar magnet 14 follows the sandwiching surface 13f having a U-shaped cross section. Make a surface shape. In any case, the multipolar magnet 14 is clamped in the radial direction and the axial direction by the clamping surfaces 13e and 13f provided on the outer periphery 14a on the inner periphery of the fixed portion 13.

  In addition, in the fixing portion 13, the portion that is folded back to the inner diameter side and can be engaged with the multipolar magnet 14 in the axial direction is formed over the entire circumference in the circumferential direction of the fixing portion 13 and is predetermined in the circumferential direction. A plurality of locations can be provided at intervals. For example, in FIG. 7, the sandwiching surface 13 a is composed of an enlarged diameter surface 13 b, a reduced diameter surface 13 d, and a cylindrical surface 13 c, and a folded portion toward the inner diameter side (a portion in which the reduced diameter surface 13 d is formed on the inner periphery in the same figure) The case where two or more are provided at predetermined intervals in the circumferential direction is illustrated.

  Further, as another configuration example of the fixing portion 13, for example, a form shown in FIG. The figure illustrates the case where the clamping surface 13a on the inner periphery of the fixed portion 13 is configured only by the cylindrical surface 13c. In this case, the compression molded body 14 ′ is sandwiched in the radial direction by the cylindrical surface 13 c due to the expansion after sintering of the compression molded body 14 ′ brought into contact with the contact portion 12 b. On the other hand, since the compression molded body 14 ′ is not restrained in the axial direction, the compression molded body 14 ′ can expand with a certain degree of freedom in the direction opposite to the contact portion 12 b (right direction in the drawing). This avoids a situation in which the compression molded body 14 ′ receives an excessive load in the anti-expansion direction from the cylindrical surface 13 c due to excessive expansion in the radial direction, and reliably prevents the sintered body 11 from being damaged. It becomes possible to fix to.

  Further, as shown in FIG. 9, a part of the clamping surface 13a of the fixing portion 13 is protruded and deformed to the inner diameter side, and the protruding portion 13g and the compression molded body 14 ′ serving as a sintered body are engaged in the circumferential direction. By doing so, the compression molded body 14 ′ can be prevented from rotating. In this case, a recess (corresponding to 14c in FIG. 9) corresponding to the protruding portion 13g of the core metal 11 is formed in the compression molded body 14 'in advance, and this recess and the protrusion of the core metal 11 are set when the core metal 11 is set. By fitting the part 13g together, the compression molded body 14 'is fixed to the fixing part 13. In addition, although the illustration is abbreviate | omitted for a rust prevention process, the said sintered compact can also form a rust prevention film, for example. For this type of anticorrosive coating, for example, a clear high anticorrosive paint can be used.

  Further, when the compression molded body 14 ′ is sintered, the heating temperature in the furnace is set to a temperature lower than the melting point of the nonmagnetic metal powder, so that the nonmagnetic metal powder is softened without melting and fixed to the magnetic powder. To do. The non-magnetic metal powder fixed to the magnetic powder acts as a binder between adjacent magnetic powders. Further, even if the non-magnetic metal powder is partially fluidized, its fluidity is low and remains on the surface of the magnetic powder particles. As a result, a sintered body in which the magnetic powder and the nonmagnetic metal powder are uniformly distributed over the entire surface is obtained without the nonmagnetic metal powder being unevenly distributed in the sintered body or flowing out to the external surface. It is done. Therefore, a high-strength sintered body (multipolar magnet 14) can be obtained.

  When using samarium iron (SmFeN) magnetic powder as the magnetic powder and tin (Sn) powder as the nonmagnetic metal powder as in this embodiment, the temperature during sintering is less than the melting point of tin (232 ° C.). It is preferable to set the temperature to be, specifically, a range of 200 to 225 ° C. Within this temperature range, the non-magnetic metal powder functions sufficiently as a binder for the magnetic powder, and a high-strength sintered body can be obtained.

  Further, in this embodiment, since a nonmagnetic metal powder (tin powder) having a maximum particle size of 45 μm is used, a mixed powder in which a small size nonmagnetic metal powder is uniformly dispersed around the magnetic powder is obtained. Therefore, a sintered body having a uniform density can be obtained by compression molding and sintering the mixed powder. Moreover, since the nonmagnetic metal powder of the said size has a small apparent density, a compression ratio becomes large when shape | molding the compression molding body of the same dimension and the same density. Thereby, the entanglement between the powders can be improved, and the strength of the sintered body can be further increased.

  In particular, in this embodiment, since the irregularly shaped tin powder (see FIG. 12B) is used as the nonmagnetic metal powder, a compression molded body in which the powders are intertwined very well is obtained. Thereby, the intensity | strength of a sintered compact can further be raised.

  Thus, the handleability of the sintered body is improved by increasing the strength of the sintered body. Moreover, when fixing the magnetic encoder 10 assembled to the rotation side member mentioned later by press-fitting the core metal 11 to the rotation side member, the sintered body magnetized by deformation | transformation of the core metal 11 accompanying press injection ( The multipolar magnet 14) is difficult to break. Therefore, it is possible to increase the tightening allowance at the time of press-fitting. Further, the disk-shaped sintered body can be thinned, thereby reducing the material cost.

  In addition, the said effect | action can be acquired also when not only a tin powder but another nonmagnetic metal powder is used. A suitable example is a tin-zinc alloy. In this case, the mixing ratio of tin and zinc is preferably 15 wt% to 40 wt% of zinc with respect to 60 wt% to 85 wt% of tin. The sintering temperature is preferably set to a temperature lower than the melting point of the tin-zinc alloy powder (about 250 ° C. in the above mixing ratio), specifically in the range of 170 to 190 ° C. If it is the tin-zinc alloy powder of the said mixture ratio, even if sintering temperature is about 170-190 degreeC, it will soften to the extent which functions as a binder of magnetic powder. Therefore, the strength of the sintered body can be improved, and by lowering the sintering temperature, it is possible to suppress the magnetic deterioration accompanying the temperature increase of the magnetic powder as much as possible. As an example, FIG. 13 shows a micrograph of the inside of the sintered body when the tin-zinc alloy powder is used.

  Moreover, since the apparent density of the tin alloy powder having the above configuration is smaller than that of tin powder of the same size, the compression ratio can be increased and the strength of the sintered body can be further increased. As the size of the alloy powder, a size of 63 μm or less can be preferably used. In order to improve the entanglement between the powders, it is preferable to use a tin-zinc alloy powder formed in a non-spherical shape, for example, by a water atomizing method or an oil atomizing method, as in the case of tin powder. .

  As described above, the disc-shaped sintered body fixed to the cored bar 11 that is a metal annular member becomes a multipolar magnet 14 by being magnetized in a multipolar manner in the circumferential direction. The multipolar magnet 14 and the cored bar 11 constitute the magnetic encoder 10 shown in FIG.

  The magnetic encoder 10 is attached to a rotation side member (not shown), and is used for rotation detection with a magnetic sensor 21 facing the multipolar magnet 14 as shown in FIG. The rotation detection device 22 is configured as described above. This figure shows a configuration example in the case where the magnetic encoder 10 is used as a component part of a seal device 5 of a bearing (not shown), and the magnetic encoder 10 is used by being incorporated in a rotation side member of the bearing. The seal device 5 includes a magnetic encoder 10 and a fixed-side seal member 9. A specific configuration of the sealing device 5 will be described later.

  When the magnetic encoder 10 is rotated, the magnetic sensor 21 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 (see FIG. 2) of the magnetic poles N and S can be set finely. For example, the accuracy that the pitch p is 1.5 mm and the pitch difference is ± 3% can be obtained. 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 position as a ratio to the target pitch. When the magnetic encoder 10 is used in the bearing sealing device 5 as shown in FIG. 4, the rotation of the bearing to which the magnetic encoder 10 is attached is detected.

  The flatness of the surface of the disk-shaped multipolar magnet 14 (here, the surface facing the magnetic sensor 21) is preferably 200 μm or less, and preferably 100 μm or less. When the flatness of the surface of the multipolar magnet 14 exceeds 200 μm, the gap (air gap) between the magnetic sensor 21 and the surface of the multipolar magnet 14 changes during the rotation of the magnetic encoder 10, thereby degrading the sensing accuracy. For the same reason, the surface runout of the surface of the multipolar magnet 14 during rotation of the magnetic encoder 10 is preferably 200 μm or less, and preferably 100 μm or less. In this embodiment, since the compression-molded body 14 ′ is expanded evenly after sintering, the flatness of the surface of the multipolar magnet 14 can be easily suppressed to the above range (200 μm or less). In this embodiment, in order to stably obtain high sensing performance, regardless of the shape of the fixing portion 13 (FIGS. 1 and 3 to 9), the multipolar magnet 14 fixed to the core metal 11 is detected. The magnetic encoder 10 is configured so that the fixed portion 13 does not protrude from the surface to the magnetic sensor 21 side.

  Next, an example of a wheel bearing provided with the magnetic encoder 10 and a configuration example of the seal device 5 will be described with reference to FIGS. As shown in FIG. 10, 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 15 for sealing the end annular space.

  The seal device 5 on one end side (constant velocity universal joint 7 side) includes a magnetic encoder 10 as a component. The inner member 1 and the outer member 2 have raceway surfaces 1a and 2a of the rolling elements 3, and each raceway surface 1a and 2a is formed in a groove shape. The inner member 1 and the outer member 2 refer to an inner peripheral member and an outer peripheral member that can be relatively rotated through the rolling elements 3, respectively. Alternatively, it may be an assembly member in which a bearing outer ring and another member are combined. 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 19 and 20. These inner rings 19, 20 are fitted on the outer periphery of the shaft portion of the hub ring 6 and constitute the inner member 1 together with the hub ring 6. It should be noted that the inner member 1 is integrated with the hub wheel 6 and one inner ring 19 instead of the three-part assembly part including the hub wheel 6 and the pair of split inner rings 19 and 20 as described above. It is good also as what consists of two components comprised by the hub ring with a track surface, and the other inner ring | wheel 20.

  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 via 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. 11 is an enlarged cross-sectional view of the sealing device 5 integrally including the magnetic encoder 10. The sealing device 5 is the same as that shown in FIG. 4 and a part of the sealing device 5 has been described above, but the details will be described with reference to FIG. In the sealing device 5, the magnetic encoder 10 or the cored bar 11 serves as a slinger, and is attached to the rotating member of the inner member 1 and the outer member 2. In this example, since the rotating member is the inner member 1, the magnetic encoder 10 is attached to the inner member 1 by means such as press fitting.

  The sealing device 5 includes annular seal plates (11) and (16) 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 is the same as the above-described configuration based on FIGS. By disposing the magnetic sensor 21 so as to face the multipolar magnet 14 in the magnetic encoder 10, a rotation detection device 22 for detecting the wheel rotation speed is configured. Of course, the magnetic encoder 10 having a configuration based on FIGS. 5 to 9 can be incorporated and used.

  The second seal plate 16 is a member constituting the seal member 9 (see FIG. 4), and slides on the side lip 17a and the attachment portion 12a which are in sliding contact with the contact portion 12b of the core metal 11 which is the first seal plate. Radial lips 17b and 17c that are in contact with each other are integrally provided. These seal lips 17 a to 17 c are provided as a part of the elastic member 17 vulcanized and bonded to the second seal plate 16. The number of the lips 17a to 17c may be arbitrary, but in the example shown in FIG. 11, one side lip 17a and two radial lips 17b and 17c (so-called triple lips) located inside and outside in the axial direction are provided. ing. The second seal plate 16 is obtained by holding an elastic member 17 in a fitting portion with the outer member 2 which is a fixed side member. That is, the elastic member 17 has a covering portion 17d that covers from the inner diameter surface of the cylindrical portion 16a to the outer diameter of the tip portion, and this covering portion 17d serves as a fitting portion between the second seal plate 16 and the outer member 2. Intervene. Further, the covering portion 17d provides a slight radial gap between the cylindrical portion 16a of the second seal plate 16 and the fixing portion 13 (the portion where the cylindrical surface 13c is formed in FIG. 11) of the core metal 11 forming the first seal plate. The labyrinth seal 18 is formed by the gap.

  According to the wheel bearing of this configuration, the rotation of the inner member 1 rotating with the wheel is detected by the magnetic sensor 21 via the magnetic encoder 10 attached to the inner member 1, and the wheel rotation speed is detected. . Since the magnetic encoder 10 is a constituent element of the sealing device 5, it can detect the rotation of the wheel without increasing the number of parts. The space of the bearing end portion in the wheel bearing is a narrow space limited by the constant velocity universal 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-mentioned. Since the thickness can be reduced by increasing the strength as described above, the rotation detector 22 can be easily arranged. As for the seal between the inner and outer members 1 and 2, sliding contact between the seal lips 17 a to 17 c provided on the second seal plate 16, and a core metal which is the first seal plate on the cylindrical portion 16 a of the second seal plate 16. And 11 labyrinth seals 18 formed by confronting each other through a slight radial gap.

  In the wheel bearing shown in FIGS. 10 and 11, the case where the multipolar magnet 14 of the magnetic encoder 10 is provided outward (opposite the magnetic sensor 21 on the right side in the figure) with respect to the bearing has been described. On the contrary, it may be provided inward with respect to the bearing (on the left side in the drawing, opposite to the magnetic sensor 21). In that case, the cored bar 11 is preferably made of a non-magnetic material.

  In addition, although the magnetic encoder 10 of the said embodiment was demonstrated as the case where all were the components of the seal device 5 of a bearing, the magnetic encoder 10 of these each embodiment is restricted to what is used as the component of the seal device 5. Instead, it can be used alone for rotation detection. For example, the magnetic encoder 10 in the embodiment of FIG. 1 may be provided in the bearing separately from the seal device 5 although illustration is omitted.

It is a fragmentary perspective view of the magnetic encoder which concerns on embodiment of this invention. It is a front view explaining the magnetic pole arrangement of a magnetic encoder. It is a fragmentary perspective view which shows an example of the method of carrying out the sintering fixation of the compression molding body to a metal core. It is sectional drawing which shows the sealing device provided with the magnetic encoder, and a magnetic sensor. It is a fragmentary perspective view which shows the other example of the method of carrying out the sintering fixation of the compression molding body to a metal core. It is a fragmentary perspective view which shows the other example of the method of carrying out the sintering fixation of the compression molding body to a metal core. It is a fragmentary perspective view which shows the other example of the method of carrying out the sintering fixation of the compression molding body to a metal core. It is a fragmentary perspective view which shows the other example of the method of carrying out the sintering fixation of the compression molding body to a metal core. It is a fragmentary perspective view which shows the other example of the method of carrying out the sintering fixation of the compression molding body to a metal core. It is sectional drawing which shows one structural example of the wheel bearing provided with the magnetic encoder. It is an expanded sectional view around the magnetic encoder of the wheel bearing. (A) is the microscope picture of the tin powder shape | molded by the gas atomization method, (b) is the microscope picture of the tin powder shape | molded by the water atomization method. It is a microscope picture inside a sintered compact at the time of using a tin-zinc alloy powder for nonmagnetic metal powder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner member 2 Outer member 3 Rolling body 5 Sealing device 7 Constant velocity universal joint 10 Magnetic encoder 11 Core metal 12a Attachment part 12b Contact part 13 Fixing part 13a Nipping surface 13b Expanded surface 13c Cylindrical surface 13d Reduced diameter surface 14 Multipolar magnet 14 Outer peripheral portion 14 'Compression molded body 17 Elastic members 17a, 17b, 17c Seal lip 18 Labyrinth seal 21 Magnetic sensor 22 Rotation detection device p Pitch

Claims (3)

In a magnetic encoder comprising a multipolar magnet formed by compressing and molding a mixed powder of magnetic powder and nonmagnetic metal powder, and a cored bar to which the multipolar magnet is fixed,
The core bar includes a fixing portion for fixing the multipolar magnet,
The magnetic encoder according to claim 1, wherein the multipolar magnet is clamped and fixed to the fixing portion by expansion after sintering.   The magnetic encoder according to claim 1, wherein the fixing portion includes a clamping surface that clamps an outer peripheral portion of the multipolar magnet.   A wheel bearing comprising the magnetic encoder according to claim 1.

Images