JP2011174796A - Wheel bearing device equipped with rotation speed detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing device equipped with a rotation speed detector, capable of not only positioning and fixing a sensor of the rotation speed detector with high accuracy, but protecting the sensor and securing airtightness between the sensor and a sensor holder. <P>SOLUTION: The wheel bearing device equipped with the rotation speed detector includes an encoder 20; the sensor holder 22 fittingly attached to an end of an outward member 1, opposed to the encoder 20; the sensor 21 fittingly fixed into a hole ha in one of surfaces of the sensor holder 22, opposed to the encoder 20, and detecting the encoder 20, opposed to the encoder 20 across a gap; and a sealing device 24 located more on an inboard side than the sensor 21. The sensor 21 is integrally molded into the sensor holder 22 by hot melt molding using a hot melt type resin, and resins on both sides catching the sensor holder 22 and the sensor 21 is connected to each other via the hole ha provided in the sensor holder 22. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wheel bearing device in which, for example, a rotational speed detecting device for a bearing portion that rotates relatively in an antilock brake system of an automobile is incorporated.

  In recent years, exports of automobile parts to Brazil, Russia, India, and China (abbreviated as BRICs) countries, where economic growth is remarkable, have been increasing. Of such automobile parts, magnetic encoders used for automobile bearings often use magnetic rubber. In BRICs, automobiles are often driven on rough roads that are still unpaved, and magnetic rubber magnetic encoders used in these automobiles are required to have higher wear resistance. For this reason, a wear prevention measure or the like has been devised in which a protective cover made of a nonmagnetic material is provided on the surface of a rubber magnetic encoder.

  However, in this case, the gap between the surface of the rubber magnetic encoder for the protective cover and the magnetic sensor disposed opposite thereto is increased, and thus a magnetic encoder having a higher magnetic flux density is required. Therefore, a wheel bearing device has been devised in which a magnetic encoder and a rotational speed detection device are built in the bearing (for example, Patent Document 1).

Japanese Patent Laying-Open No. 2005-300289

When the rotational speed detection device is built in the bearing, the sensor of the rotational speed detection device may come into contact with grease that is a lubricant for the bearing. For this reason, it is necessary to mold and protect the sensor by covering it with a resin or the like. Further, since the cable for outputting the sensor signal is taken out from the bearing through the hole provided in the annular sensor holder, it is necessary to prevent intrusion of water, dust and the like from the outside of the bearing.
In order to solve this problem, it is conceivable to seal the hole from which the cable is taken out and to ensure airtightness by integrally molding the sensor and the annular sensor holder.

The sensor needs to be positioned with high accuracy in order to secure a gap with the magnetic encoder. For this purpose, it is necessary to fix and position the sensor in advance in the mold during molding. However, it is not easy to position the sensor in the mold with high accuracy, which causes an increase in cost.
In order to solve this problem, it is conceivable that the sensor is fixed and positioned with high accuracy by fitting into a hole provided in an annular sensor holder. By setting the sensor to be fitted and fixed in advance, it becomes easy to manage the position of the sensor in the mold during molding, and the molding cost can be reduced.

  There is a method of covering the sensor with a well-known thermosetting potting material as a method for protecting the surroundings with resin or the like by integrally molding the sensor of the rotational speed detection device and sealing the hole to ensure airtightness. . However, potting requires extra man-hours for thermosetting. Another method is to cover the sensor with resin by injection molding. Since injection molding is performed in a relatively high temperature and high pressure environment, the mold for resin molding also requires strength to withstand the temperature and pressure. These cause the manufacturing cost to increase. Furthermore, if the sensor itself cannot withstand the pressure at the time of injection molding, or if the temperature at the time of molding exceeds the range of the guaranteed operation temperature of the sensor, the sensor performance may be affected. Further, the adhesiveness between the injection-molded resin and the sensor and sensor holder is not sufficient, and it may be difficult to ensure airtightness.

  An object of the present invention is to position and fix a sensor of a rotational speed detection device with high accuracy, to protect the sensor and to secure airtightness between the sensor and the sensor holder, and to provide a wheel bearing device with a rotational speed detection device. Is to provide.

  In the wheel bearing device with a rotational speed detection device of the present invention, an outer member serving as a stationary member having a double row rolling surface formed on the inner periphery, and a rolling surface facing each of the rolling surfaces on the outer periphery. In a wheel bearing device comprising an inner member formed as a rotation side member and a double row rolling element interposed between these opposing rolling surfaces, the wheel bearing device for rotatably supporting the wheel with respect to the vehicle body, An annular encoder that is attached to the outer periphery near the inboard side end of the side member and changes in magnetic properties along the circumferential direction, and is fitted to the end of the outer member facing the encoder An annular sensor holder mounted in a state, and fitted and fixed in a hole provided in a surface of the sensor holder that faces the encoder, and the encoder is magnetically detected by facing the encoder through a gap. Sensor and more And a sealing device that seals between the sensor holder and the inner member, and the sensor is formed into the annular sensor holder by hot melt molding using a hot melt resin. The resin molded on both sides sandwiching the sensor holder and the sensor is connected through a hole provided in the sensor holder.

  The hot melt molding is performed by using a resin having a low environmental load and excellent workability and adhesiveness as compared with conventional molding methods. The resin material used for hot melt molding is injected at a lower temperature and lower pressure than potting, and the injection time is short and the curing speed is high. For this reason, for example, molding is possible with a simple mold made of inexpensive aluminum or the like, and the production cost of the mold can be kept lower than that of the conventional product. In addition, since the manufacturing equipment is low in both heat resistance and pressure resistance compared to general injection molding, the cost required for the manufacturing equipment can be kept low. Furthermore, since the molding is performed in a low temperature / low pressure environment, the pressure applied to the sensor during molding can be relaxed, and the temperature at the time of molding can be, for example, lower than the operation guarantee temperature of the sensor. Therefore, the possibility of damage to the sensor is reduced and the yield is improved. In addition, since the hot melt resin has good adhesiveness, it is possible to ensure good airtightness between the sensor and the sensor holder. Therefore, the hole of the sensor holder can be more reliably sealed, and it is possible to prevent intrusion of water, dust and the like from the outside of the bearing.

  Since the sensor is fitted and fixed in the hole of the sensor holder and is molded integrally with the sensor holder, the sensor position in the mold can be easily managed at the time of molding, and the molding cost can be reduced. . Furthermore, since the resin on both sides sandwiching the sensor holder and the sensor are connected via a hole provided in the sensor holder, the resin covering the sensor is more firmly bonded to improve the airtightness than that of the prior art. Can be planned. Further, since the sealing device for sealing between the sensor holder and the inner member is provided, it is possible to prevent the encoder from being worn by a foreign matter or the like from the outside of the bearing, thereby enabling accurate rotation detection.

  The hole of the sensor holder is provided with a plurality of protrusions for fitting and fixing the sensor and an opening formed between adjacent protrusions, and the opening is filled with the hot melt resin. May be. Thus, by fitting and fixing the sensor to the protruding portion of the hole of the sensor holder, the sensor position in the mold can be easily managed during molding. The tip portions of the plurality of protrusions can be elastically deformed so that the sensor can be easily and accurately fitted and fixed at a predetermined sensor position in the mold, so that the number of manufacturing steps can be reduced. Furthermore, since the hot melt resin is filled in the opening, the mold portion is connected, and the air tightness is improved in combination with the hot melt resin having good adhesiveness.

The encoder is an axial encoder whose detected surface is arranged on the inboard side of the sensor and faces in the axial direction, and the sensor may be opposed to the encoder via an axial gap. good.
The encoder includes a conical inclined surface with respect to the axial direction, the annular sensor holder faces the conical inclined surface with respect to the encoder axial direction, and a sensor integrally molded with the sensor holder includes the encoder It may be attached to the end of the outer member so as to be arranged on the inboard side. In this case, the cross section seen by cutting the encoder along a plane along the bearing axial direction can be made triangular, and the structure can be strengthened. Furthermore, the encoder is disposed at the same axial position as the sensor holder by making the detected surface of the encoder a conical slope. Therefore, the axial length of the entire wheel bearing device can be shortened by the axial length of the encoder, and the device can be made compact.

The sensor may be integrally molded with the annular sensor holder by hot melt molding using a polyamide-based hot melt resin.
The sensor may be integrally molded with the annular sensor holder by hot melt molding using a polyester-based hot melt resin.
The sensor may be integrally molded with the annular sensor holder by hot melt molding using a polyurethane-based hot melt resin.

The encoder is a magnetic encoder in which a multipolar magnet in which magnetic poles are alternately arranged in a circumferential direction is formed, the multipolar magnet including magnetic powder and thermoplastic resin, and the thermoplastic resin containing the magnetic powder The melt viscosity may be 30 Pa · s or more and 1500 Pa · s or less.
If the melt viscosity of the thermoplastic resin containing magnetic powder is smaller than 30 Pa · s, a large amount of burrs are generated during molding, and it becomes difficult to mold appropriately. If the melt viscosity of the thermoplastic resin is greater than 1500 Pa · s, it will be difficult to knead the magnetic powder into the thermoplastic resin. In particular, when the ratio of the magnetic powder is increased, the kneading failure becomes remarkable. Therefore, by setting the melt viscosity of the thermoplastic resin containing the magnetic powder to 30 Pa · s or more and 1500 Pa · s or less, a magnetic encoder with good productivity can be obtained. This improvement in the productivity of the magnetic encoder also leads to an improvement in the productivity of the wheel bearing device with a rotation detection device.

The thermoplastic resin may include one or more compounds selected from the group consisting of polyamide 12, polyamide 612, polyamide 11, and polyphenylene sulfide.
These thermoplastic resins have very low swelling (less than 10%) even when immersed in grease used as a lubricant for bearings at high temperatures, so they have poor water absorption, condensation at low temperatures, salt water and muddy water. It is resistant to deterioration even in an environment with a lot of moisture such as rain water, and is particularly effective as a material for a magnetic encoder incorporated in a wheel bearing device.

The magnetic powder may be a ferrite-based magnetic powder. Since ferrite magnetic powder is difficult to oxidize, the anticorrosion of the magnetic encoder can be improved.
The magnetic powder may be anisotropic ferrite magnetic powder.

The magnetic encoder may be one in which a magnet to be detected is formed by injection molding.
The plastic magnet of the magnetic encoder may be a magnetic field formed by injection molding. In this way, a plastic magnetic encoder having a higher magnetic flux density can be obtained by magnetic field molding of the plastic magnet.

  In the wheel bearing device with a rotational speed detection device of the present invention, an outer member serving as a stationary member having a double row rolling surface formed on the inner periphery, and a rolling surface facing each of the rolling surfaces on the outer periphery. In a wheel bearing device comprising an inner member formed as a rotation side member and a double row rolling element interposed between these opposing rolling surfaces, the wheel bearing device for rotatably supporting the wheel with respect to the vehicle body, An annular encoder that is attached to the outer periphery near the inboard side end of the side member and changes in magnetic properties along the circumferential direction, and is fitted to the end of the outer member facing the encoder An annular sensor holder mounted in a state, and fitted and fixed in a hole provided in a surface of the sensor holder that faces the encoder, and the encoder is magnetically detected by facing the encoder through a gap. Sensor and more And a sealing device that seals between the sensor holder and the inner member, and the sensor is formed into the annular sensor holder by hot melt molding using a hot melt resin. The resin molded on both sides sandwiching the sensor holder and the sensor are connected via a hole provided in the sensor holder. For this reason, it is possible to position and fix the sensor of the rotational speed detection device with high accuracy, to protect the sensor, and to ensure airtightness between the sensor and the sensor holder.

It is sectional drawing of the wheel bearing apparatus with a rotational speed detection apparatus which concerns on one Embodiment of this invention. It is an expanded sectional view of the principal part of the bearing apparatus for wheels. It is a front view of the encoder of the wheel bearing device. It is sectional drawing of the principal part explaining the state which fits a sensor in the hole of the sensor holder of the bearing apparatus for wheels. It is an enlarged front view of the principal part of the sensor holder of the bearing apparatus for wheels. It is a figure explaining the method of integrally molding the sensor of the bearing apparatus for wheels to a sensor holder by hot-melt molding, (A) is a figure which shows the step which inject | pours hot-melt resin into a cavity, (B) is a sensor. The figure which shows the step which carries out fitting fixation to the hole of an embedding protrusion, (C) is a figure which shows the step which closes the opening edge part of the said hole. (A) is an expanded sectional view of the principal part of the bearing device for wheels concerning other embodiments of this invention, and (B) is an expanded sectional view near the sensor of Drawing 7 (A). (A) is an expanded sectional view of the principal part of the bearing device for wheels concerning other embodiments of this invention, and (B) is an expanded sectional view near the sensor of Drawing 8 (A). (A) is a side view of a sensor holder of a wheel bearing device according to still another embodiment of the present invention, (B) is an enlarged view of the hole of the sensor holder, and (C) is a hole of the sensor holder. It is a figure which shows the state which made the sensor fit.

  An embodiment of the present invention will be described with reference to FIGS. The wheel bearing device with a rotation speed detection device of this embodiment is, for example, a double row angular contact ball bearing type classified as a third generation type, and is an inner ring rotation type and a drive wheel support type. However, it is not limited to this form. In this specification, the side closer to the outer side in the vehicle width direction of the vehicle with the wheel bearing device attached to the vehicle is referred to as the outboard side, and the side closer to the center of the vehicle is referred to as the inboard side. First, the wheel bearing device will be described, and then the rotational speed detection device will be described. The following description also includes a description of a method for manufacturing a wheel bearing device with a rotational speed detection device.

  As shown in FIG. 1, the wheel bearing device includes an outer member 1, an inner member 2, and double row rolling elements 3. Double-row rolling surfaces 4 are formed on the inner periphery of the outer member 1, and rolling surfaces 5 facing the respective rolling surfaces 4 of the outer member 1 are formed on the outer periphery of the inner member 2. Yes. Between the rolling surfaces 4 and 5 of the outer member 1 and the inner member 2, double-row rolling elements 3 are interposed. The rolling elements 3 are formed of balls and are held by the cage 6 for each row. The rolling surfaces 4 and 5 have a circular arc shape in cross section, and the rolling surfaces 4 and 5 are formed so that the contact angles are back to back. The end of the bearing space between the outer member 1 and the inner member 2 is sealed by a sealing device 7.

  The outer member 1 is a fixed-side member, and has a flange 1a for mounting a vehicle body attached to a knuckle 9 in a suspension device 8 of the vehicle body on the outer periphery, and is formed as an integral part as a whole. The flange 1a is provided with bolt holes 1aa for mounting the vehicle body at a plurality of locations in the circumferential direction, and a knuckle bolt 10 inserted from the inboard side into the bolt insertion hole 9a of the knuckle 9 is screwed into the bolt hole 1aa of the flange 1a. By joining, the flange 1a is bolted to the knuckle 9.

  The inner member 2 is a rotation side member, and includes a hub ring 11 and an inner ring 12. The hub wheel 11 has a hub flange 11a for wheel mounting. The inner ring 12 is fitted to the outer periphery of the end of the inboard side of the shaft portion 11 b of the hub wheel 11. The hub ring 11 and the inner ring 12 are formed with the rolling surfaces 5 of the respective rows. An inner ring fitting surface 13 having a small diameter with a step is provided on the outer periphery of the inboard side end of the hub wheel 11, and the inner ring 12 is fitted to the inner ring fitting surface 13. A through hole 14 is provided in the center of the hub wheel 11. The stem portion 16a of the outer ring 16 of the constant velocity joint 15 is inserted into the through hole 14, and the inner member 2 is sandwiched between a stepped surface around the proximal end of the stem portion 16a and a nut 17 screwed to the distal end. Thus, the wheel bearing device and the constant velocity joint 15 are connected.

  The hub flange 11a is provided with press-fit holes 11aa for hub bolts 18 at a plurality of locations in the circumferential direction. In the vicinity of the base portion of the hub flange 11a of the hub wheel 11, a cylindrical pilot portion 19 for guiding a brake rotor and a wheel (not shown) protrudes toward the outboard side. With the guidance of the pilot portion 19, the brake rotor and the wheel are overlapped on the hub flange 11 a and fixed with the hub bolt 18.

  FIG. 2 is an enlarged cross-sectional view of part A in FIG. An encoder 20 is fitted and attached to the inboard side end of the outer peripheral surface of the inner member 2. An annular sensor holder 22 in which a sensor 21 for magnetically detecting the magnetic flux of the encoder 20 is embedded is attached to the inboard side end of the outer member 1. The encoder 20 and the sensor 21 constitute a rotation speed detection device 23 that detects the rotation of the inner member 2 integral with the encoder 20, that is, the rotation of the wheel.

  The encoder 20 is an axial type magnetic encoder in which the surface to be detected faces in the axial direction, and is a single piece of an annular multipolar magnet having an L-shaped cross section composed of a cylindrical portion 20a and a standing plate portion 20b. The cylindrical portion 20a is press-fitted and fixed to the outer peripheral surface of the inner member 2 (here, the outer peripheral surface of the inner ring 12). The upright plate portion 20b rises to the outer diameter side from the outer end of the bearing in the axial direction of the cylindrical portion 20a. An annular sealing device fitting projection 20ba is provided in the vicinity of the outward base end of the standing plate portion 20b, and the inner peripheral surface of the sealing device fitting projection 20ba is the first seal of the sealing device 24. The end portion of the plate 25 is fitted to the outer peripheral surface. Further, the outer peripheral surface of the sealing device fitting protrusion 20ba is inclined to the outer diameter side toward the bearing inner side. By providing such a sealing device fitting protrusion 20ba, the rigidity of the encoder 20 as a whole is increased, thereby accurately maintaining the gap between the surface of the encoder 20 and the sensor 21 disposed opposite thereto. It becomes possible.

As shown in FIG. 3, the multipolar magnet is an annular member magnetized in multiple poles so that magnetic poles N and S are alternately arranged in the circumferential direction, and includes magnetic powder and a thermoplastic resin as a binder. It is considered as an injection-molded product including The magnetic poles N and S are formed to have a predetermined pitch P in the pitch circle diameter PCD.
The thermoplastic resin has a melt viscosity of 30 Pa · s to 1500 Pa · s. If the melt viscosity of the thermoplastic resin contained in the magnetic encoder is smaller than 30 Pa · s, a large amount of burrs are generated during injection molding, making it difficult to mold appropriately. If the melt viscosity of the thermoplastic resin is greater than 1500 Pa · s, it will be difficult to knead the magnetic powder into the thermoplastic resin. In particular, when the proportion of the magnetic powder is increased, the kneading failure becomes remarkable. Therefore, by setting the melt viscosity of the thermoplastic resin within the above range, a magnetic encoder with good productivity can be obtained. Moreover, it leads also to the productivity improvement of the wheel bearing apparatus with a rotational speed detection apparatus.

  The thermoplastic resin included in the magnetic encoder includes polyamide 12, polyamide 612, polyamide 11, and poniphenylene sulfide, which have a very small expansion (less than 10%) even when immersed in grease used as a lubricant in a bearing at a high temperature. It is preferable to include one or more compounds selected from the group consisting of: Since these thermoplastic resins are poor in water absorption, they are resistant to deterioration even in an environment with a lot of moisture such as dew condensation at a low temperature, and are particularly effective as a material for the encoder 20 incorporated in the wheel bearing device.

  Barium-based or strontium-based ferrite powder is used as the magnetic powder that is a material of the multipolar magnet. In the case of a ferrite magnetic powder, it may be an isotropic ferrite magnetic powder or an anisotropic ferrite magnetic powder. Since such ferrite-based magnetic powder is difficult to oxidize, the anticorrosion property of the encoder 20 can be improved. In addition, when the magnetic force is insufficient with only the ferrite magnetic powder, rare earth magnetic powder such as samarium iron magnetic powder or neodymium iron magnetic powder may be mixed with the ferrite magnetic powder and used.

As shown in FIGS. 2, 4, and 5, the sensor holder 22 is attached to the outer member 1 as described above. The sensor holder 22 has a hole ha for positioning and fitting and fixing the sensor 21. The sensor 21 is fitted and fixed in the hole ha and embedded in the sensor holder 22. The sensor 21 embedded in the sensor holder 22 is opposed to the upright plate portion 20b of the encoder 20 in the bearing inner position and in the axial direction through a gap defined with the upright plate portion 20b. In other words, the detected surface of the upright plate portion 20b of the encoder 20 is disposed on the inboard side of the sensor 21, and the sensor 21 faces the detected surface of the upright plate portion 20b via an axial gap. .
The sensor 21 includes, for example, a magnetic detection element that changes characteristics according to the flow direction of magnetic flux, such as a Hall element, a magnetoresistive element (abbreviated as MR element), and a waveform shaping that adjusts the output waveform of the magnetic detection element. And an integrated circuit (abbreviated as IC) in which a circuit is incorporated.
The annular sensor holder 22 has an annular cored bar 26 and a sensor holder 27. The core metal 26 includes an outer diameter cylindrical portion 26a that is press-fitted and attached to the outer peripheral surface of the outer member 1, a flange portion 26b that extends from the inboard side end of the outer diameter cylindrical portion 26a toward the inner diameter side, and the flange portion 26b. And an inner diameter cylindrical portion 26c extending from the inner diameter side end to the axial inboard side. The cored bar 26 is formed by, for example, pressing a stainless steel plate having corrosion resistance.

  Perforations 28 are formed at a plurality of positions in the circumferential direction of the inner diameter cylindrical portion 26c in the cored bar 26, and a resin sensor holder 27 is integrally molded at a portion extending from the inner diameter cylindrical portion 26c to the flange portion 26b. With the outer diameter cylindrical portion 26 a of the cored bar 26 press-fitted into the outer peripheral surface of the outer member 1, the sensor holder 22 of the outer member 1 is in a state where the flange portion 26 b is in close contact with the inboard side end surface of the outer member 1. Fixed to the inboard side edge.

The sensor 21 is integrally molded in an annular sensor holder 22 by hot melt molding using a hot melt type resin (referred to as “hot melt resin”).
The “hot melt molding” is resin molding in which a solventless thermoplastic hot melt resin melted at a relatively low temperature is injected into a mold using, for example, a gear pump or a pneumatic pump.

  The sensor holding body 27 is provided with sensor embedded protrusions 27a protruding from the perforations 28 at a plurality of positions in the circumferential direction of the inner diameter cylindrical part 26c by a distance determined inward in the radial direction. The sensor 21 is integrally molded by hot melt molding on the sensor embedding protrusion 27a, and the resin on both surfaces (in this example, both axial surfaces) sandwiching the sensor 21 passes through the hole ha provided in the sensor holder 22. Connected through. The portion of the resin connected through the hole ha is referred to as “molding resin portion J1”.

  The hole ha is formed, for example, in a substantially rectangular hole shape in front view, as shown in FIG. 5, according to the shape of the sensor 21 (that is, the width direction dimension, the radial direction dimension, and the thickness). In this example, the hole ha is provided with a plurality of openings h1 for filling the hot melt type resin after positioning the sensor 21 at the four corners of the rectangular hole. For example, the holes ha are provided at a plurality of locations in the circumferential direction of the sensor holding body 27. The plurality of holes ha are formed at equal distances from the axial center of the sensor holding body 27 in the radial direction. In a state where the sensor 21 is placed and supported at the bottom of each hole ha, the plurality of openings h1 and the opening edge h2 of the hole ha are closed by the molding resin part J1. Thereby, the sensor holder 22 and the molding resin parts J1 on both sides sandwiching the sensor 21 are connected via the hole ha.

The melting temperature of the hot melt resin is approximately 120 ° C. or higher and 250 ° C. or lower, preferably 160 ° C. or higher and 230 ° C. or lower. The injection pressure of the hot melt resin into the mold is 0.2 MPa or more and 9.8 MPa or less (2 kg / cm ² or more and 100 kg / cm ² or less), preferably 3.43 MPa (35 kg / cm ² ) or less. Further, it is preferable to use a resin having a melt viscosity of about 1000 mPa · s to about 150,000 mPa · s (210 ° C.) in order to spread the molten resin to every corner of the mold.

The hot melt resin is not particularly limited as long as it can be injected at the above melting temperature and injection pressure. For example, one or more compounds selected from the group consisting of polyamide, polyester, polyurethane, polyolefin, and the like A resin containing can be used. One compound that does not use a solvent, in other words, a solvent-free one-component thermoplastic resin can be used.
Specific examples of the polyamide-based resin include a polyamide hot melt resin manufactured by France TRL, “Macromelt (trademark)” manufactured by Henkel Japan Ltd., and the like. Specific examples of the polyester-based resin include “Copolymerized polyester Byron (trademark)” manufactured by Toyobo Co., Ltd. and “Aronmelt PES (trade name)” manufactured by Toa Gosei Co., Ltd. Specific examples of the polyurethane-based resin include “Macromelt (trademark)” by Henkel Japan K.K. Specific examples of polyolefin resins include “Aronmelt MD (trade name)” manufactured by Toa Gosei Co., Ltd.

A method of integrally molding the sensor 21 on the sensor holder 22 by hot melt molding will be described.
As shown in FIG. 6A, after the core metal 26 is set in a mold 31 having an upper mold 29 and a lower mold 30, and the mold is clamped, the above-mentioned molten hot melt resin is injected with a predetermined injection pressure. Inject into the cavity 32 in the mold 31. The cavity 32 is formed in an annular groove around the axis center L1 of the sensor holder 27. The cavity 32 has an annular groove portion 32a having a rectangular cross section forming most of the sensor holding body 27 and an annular groove portion 32b having a rectangular cross section forming the sensor embedding protrusion 27a.

When the molten hot melt resin is injected into the cavity 32, the hole ha for positioning and holding the sensor 21 is formed in the sensor embedded protrusion 27a of the sensor holding body 27.
After the injected hot melt resin is cured, as shown in FIG. 6B, the upper mold and the lower mold 30 are opened, and the sensor 21 is fitted and fixed in the hole ha of the sensor embedding protrusion 27a. In this case, the four corners of the sensor are fitted into the four corners of the hole ha while the bottom surface of the sensor 21 is placed and supported on the bottom of the hole ha. Thereafter, as shown in FIG. 6C, the upper mold 29A and the lower mold 30 are clamped again, and the plurality of openings h1 and the opening edge h2 of the hole ha are closed with hot melt resin. Thereby, the sensor 21 is embedded in the sensor holder 22 as shown in FIG.

As shown in FIG. 2, the space between the inner periphery of the sensor holder 22 and the outer periphery of the inner member 2 is sealed by a sealing device 24 installed at a position outside the bearing relative to the encoder 20. The sealing device 24 includes annular first and second sealing plates 25 and 34 attached to the outer peripheral surface of the inner member 2 and the inner peripheral surface of the sensor holder 22, respectively.
The first seal plate 25 has a cross section L formed of a cylindrical portion 25a that is press-fitted and attached to the outer peripheral surface of the inner member 2, and a vertical plate portion 25b that extends from the inboard side end of the cylindrical portion 25a to the outer diameter side. It is formed in a letter shape. The first seal plate 25 is formed, for example, by pressing an austenitic stainless steel plate or a cold-rolled steel plate that has been rust-proofed.

  The second seal plate 34 includes a cylindrical portion 34a that is press-fitted and attached to the inboard side of the inner peripheral surface of the sensor holder 22, and a standing plate portion 34b that extends from the outboard side end of the cylindrical portion 34a toward the inner diameter side. The cross section is formed in an inverted L shape. The second seal plate 34 is disposed such that the standing plate portion 34b is positioned on the outboard side with respect to the standing plate portion 25b of the first sealing plate 25 and faces the standing plate portion 25b in the axial direction. Is done. A seal member 35 having a side lip 35a, a grease lip 35b, and an intermediate lip 35c is vulcanized and bonded to the second seal plate 34. The seal member 35 is made of an elastic member such as rubber. The side lip 35 a is in sliding contact with the upright plate portion 25 b of the first seal plate 25, and the grease lip 35 b and the intermediate lip 35 c are in sliding contact with the cylindrical portion 25 a of the first seal plate 25. The tip of the upright plate portion 25b of the first seal plate 25 is opposed to the cylindrical portion 34a of the second seal plate 34 with a slight radial gap to constitute a labyrinth seal. The sealing device 24 seals the inboard side end in the bearing space between the outer member 1 and the inner member 2.

  According to the wheel bearing device with a rotational speed detection device having the above-described configuration, the encoder 20 integrated with the inner member 2 rotates as the wheel rotates. At this time, the sensor 21 facing the multipolar magnet in the axial direction through a predetermined gap reads the change in magnetic force of the magnetic poles N and S of the encoder 20. Thereby, the rotational speed detection apparatus 23 which has the encoder 20 and the sensor 21 can detect rotation of a wheel.

  The hot melt molding is performed by using a resin having a low environmental load and excellent workability and adhesiveness as compared with conventional molding methods. The resin material used for hot melt molding is injected at a lower temperature and lower pressure than potting, and the injection time is short and the curing speed is high. For this reason, for example, molding is possible with a simple mold made of inexpensive aluminum or the like, and the production cost of the mold can be kept lower than that of the conventional product. In addition, since the manufacturing equipment is low in both heat resistance and pressure resistance compared to general injection molding, the cost required for the manufacturing equipment can be kept low. Furthermore, since the molding is performed in a low temperature / low pressure environment, the pressure applied to the sensor during molding can be relaxed, and the temperature at the time of molding can be, for example, lower than the operation guarantee temperature of the sensor. Therefore, the possibility of damage to the sensor is reduced and the yield is improved. Moreover, since the hot melt resin has good adhesiveness, it is possible to ensure good airtightness between the sensor 21 and the sensor holder 22. Therefore, the hole ha and the like of the sensor holder 22 can be more reliably sealed, and intrusion of water, dust and the like from the outside of the bearing can be prevented.

  Since the sensor 21 is fitted and fixed in the hole ha of the sensor holder 22 and is molded integrally with the sensor holder 22, the sensor position in the mold can be easily managed at the time of molding, and the molding cost can be reduced. Is possible. Further, since the molding resin portions J1 on both sides sandwiching the sensor holder 22 and the sensor 21 are connected via the hole ha provided in the sensor holder 22, the resin covering the sensor 21 is more firmly bonded to the conventional technology. The airtightness can be improved compared to the above. In addition, since the sealing device 24 for sealing between the sensor holder 22 and the inner member 2 is provided, it is possible to prevent the encoder 20 from being worn by foreign matter from the outside of the bearing, thereby detecting accurate rotation. Yes.

  As another embodiment of the present invention, as shown in FIG. 7, in the rotational speed detection device 23 </ b> A, the encoder 20 </ b> A is press-fitted and fixed to the outer peripheral surface of the inner member 2, and the bearing inner side. Is a single annular multipolar magnet having a conical inclined surface 20Ab with respect to the axial direction in which the diameter becomes large. The inclined surface 20Ab is a detected surface. Further, the sensor embedded protrusion 27Aa of the sensor holding body 27A has a conical inclined surface 36 parallel to the inclined surface 20Ab of the encoder 20A at the corner between the tip surface and the bearing inner surface.

  The sensor 21 is fitted and fixed in the hole ha provided in the slope 36 facing the slope 20Ab of the encoder 20A in the sensor embedding protrusion 27Aa. Thereafter, as described above, the opening h1 (FIG. 5) of the hole ha and the opening edge h2 of the hole ha are closed with hot melt resin. Thereby, the sensor holder 22 and the molding resin parts J1 on both sides sandwiching the sensor 21 are connected via the hole ha. In addition, the sensor 21 is embedded in the sensor holder 22.

  The inclined surface 20Ab of the encoder 20A, the inclined surface 36 of the sensor embedding protrusion 27Aa, and the sealing device 24 can prevent foreign matter from entering from the outside and more reliably prevent the encoder 20A from being worn. Since the detection surface of the encoder 20A is a conical inclined surface 20Ab, a cross section viewed by cutting the encoder 20A along a plane along the bearing axial direction can be made into a triangular shape, and the structure can be strengthened. . Further, since the sensor embedded protrusion 27Aa is disposed at the same axial position as the sensor holder 22, the axial length of the entire wheel bearing device can be shortened by the axial length of the encoder 20A. Can be realized.

  Since the sensor 21 is fitted and fixed in the hole ha of the sensor holder 22 and is molded integrally with the sensor holder 22, the sensor position in the mold can be easily managed at the time of molding, and the molding cost can be reduced. It becomes possible. Further, since the resin on both sides sandwiching the sensor holder 22 and the sensor 21 are connected via the hole ha provided in the sensor holder 22, the resin covering the sensor 21 is more firmly bonded and more airtight than that of the prior art. Can be improved. In addition, since the sealing device 24 for sealing between the sensor holder 22 and the inner member 2 is provided, it is possible to prevent the encoder 20A from being worn by foreign matter from the outside of the bearing, thereby detecting accurate rotation. Yes.

  In the example of FIG. 8, a hole ha for fitting and fixing the sensor 21 is formed in the metal core 26 of the sensor holder 22. The sensor 21 is integrally molded with the sensor holder 22 by hot melt molding in a state where the sensor 21 is fitted and fixed in the hole ha of the metal core 26. In this case, since the molding resin portion J1 on the side facing the sensor holder 22 and the sensor 21 is connected to the molding resin portion J1 filled in the opening h1 of the hole ha, the airtightness can be improved as compared with the prior art. In addition, the process is simplified and the mold structure is simplified as compared with the case where the sensor 21 is fitted and fixed to the sensor holder. Therefore, the manufacturing cost can be reduced as compared with those shown in FIGS.

  In the example of FIG. 9, the hole ha of the sensor holder 22 has a so-called flower shape having a protrusion 37 and an opening 38 as shown in the figure. That is, a plurality of (four in this example) projections 37 for fitting and fixing the sensor 21 and an opening 38 formed between adjacent projections 37 and 37 are provided in the hole ha of the sensor holder 22. The opening 38 is filled with a hot melt resin. In this manner, by fitting and fixing the sensor 21 to the protrusion 37 of the hole ha of the sensor holder 22, the sensor position in the mold can be easily managed during molding. The tip portions of the plurality of protrusions 37 are elastically deformed, and the sensor 21 can be easily and accurately fitted and fixed at a predetermined sensor position in the mold, so that the number of manufacturing steps can be reduced. it can. Furthermore, since the hot melt type resin is filled in the opening 38, the mold part is connected, and the air tightness is improved in combination with the hot melt type resin having good adhesiveness.

In each of the above embodiments, the encoder may use a multi-pole magnet as a detected part as a plastic magnet. This plastic magnet may be formed by injection molding. The plastic magnet may be formed by magnetic field molding in injection molding. In this case, for example, a magnetic field is generated in the mold and magnetization is performed in the cooling process of injection molding, so that the magnetization process as the secondary processing can be reduced. Therefore, manufacturing cost can be reduced.
In this way, a plastic magnetic encoder having a higher magnetic flux density can be obtained by magnetic field molding of the plastic magnet. Even when such a plastic magnetic encoder is used, in particular, by using the structure shown in FIG. 7, that is, the sealing device 24, the conical slope 36, and the slope 20Ab, it is possible to prevent intrusion of foreign matters from the outside of the bearing. This can more reliably prevent the plastic magnetic encoder from being worn. In the case of employing the structure of FIG. 2, that is, the sealing device 24, the labyrinth encoder 20, and the sensor embedding protrusion 27 a, it is possible to similarly prevent foreign matters from entering.

The wheel bearing device of the present invention can also be applied to a double row tapered roller bearing type or a driven wheel supporting type. In addition, the axial fixation of the inner ring 12 with respect to the hub ring 11 may be coupled by caulking a part of the shaft portion 11b without using the constant velocity joint. The wheel bearing device may be a so-called second generation type in which the inner member has a double row of inner rings and a hub for fitting the inner rings to the outer periphery of the shaft portion. In the wheel bearing device, the inner member is constituted by a hub wheel and a joint outer ring which is one joint member of a constant velocity joint, and a rolling surface of each row is formed on the hub wheel and the joint outer ring. A fourth generation type may be applied.
The encoder may be a radial encoder whose detected surface faces in the radial direction, and the sensor may be opposed to the encoder via a radial gap.
The sensor holding body 27 is provided with the penetrating hole ha, a step portion for positioning the sensor 21 is provided in the hole ha, and the hole ha is filled with the sensor 21 positioned in the step portion of the hole ha. The sensor 21 may be integrally molded so as to sandwich the molding resin portion J1.

DESCRIPTION OF SYMBOLS 1 ... Outer member 2 ... Inner member 3 ... Rolling elements 4, 5 ... Rolling surface 20, 20A ... Encoder 21 ... Sensor 22 ... Sensor holder 37 ... Projection part 38 ... Opening part ha ... Hole 20Ab ... Slope

Claims (13)

An outer member that is a fixed side member with a double row rolling surface formed on the inner periphery, an inner member that is a rotating side member that has a rolling surface that faces each of the rolling surfaces on the outer periphery, and these facing members A wheel bearing device for supporting a wheel rotatably with respect to a vehicle body, comprising:
An annular encoder attached to the outer periphery in the vicinity of the inboard side end of the inner member and having a magnetic property that changes along the circumferential direction;
An annular sensor holder attached to the end of the outer member in a fitted state facing the encoder;
A sensor that is fitted and fixed in a hole provided in a surface of the sensor holder that faces the encoder, and that detects the encoder magnetically while facing the encoder through a gap;
A sealing device that is located on the inboard side of the sensor and seals between the sensor holder and the inner member;
The sensor is integrally molded with the annular sensor holder by hot melt molding using a hot melt resin, and the resin on both sides sandwiching the sensor holder and the sensor passes through holes provided in the sensor holder. A bearing device for a wheel with a rotational speed detection device, wherein the wheel bearing device is connected.   2. The hole of the sensor holder is provided with a plurality of protrusions for fitting and fixing the sensor and an opening formed between adjacent protrusions, and the hot melt mold is formed in the opening. A bearing device for a wheel with a rotational speed detection device filled with a resin.   The encoder according to claim 1 or 2, wherein the encoder is an axial type encoder in which a detected surface is disposed on an inboard side of the sensor and faces in an axial direction, and the sensor has an axial clearance with respect to the encoder. A wheel bearing device with a rotational speed detection device opposed to each other.   3. The encoder according to claim 1, wherein the encoder includes a conical inclined surface with respect to an axial direction, the annular sensor holder faces the conical inclined surface with respect to an encoder axial direction, and the sensor holder A wheel bearing device with a rotational speed detection device attached to an end of the outer member so that a sensor integrally molded with the encoder is disposed on the inboard side of the encoder.   5. The rotational speed detection device according to claim 1, wherein the sensor is integrally molded with the annular sensor holder by hot melt molding using a polyamide-based hot-melt resin. 6. Wheel bearing device.   5. The rotational speed detection device according to claim 1, wherein the sensor is integrally molded with the annular sensor holder by hot melt molding using a polyester-based hot melt resin. 6. Wheel bearing device.   5. The rotational speed detection device according to claim 1, wherein the sensor is integrally molded with the annular sensor holder by hot melt molding using a polyurethane-based hot melt resin. Wheel bearing device.   8. The encoder according to claim 1, wherein the encoder is a magnetic encoder in which a multipolar magnet in which magnetic poles are alternately arranged in a circumferential direction is formed, and the multipolar magnet includes magnetic powder and thermoplasticity. A wheel bearing device with a rotational speed detection device, wherein the melt viscosity of the thermoplastic resin containing the magnetic powder is 30 Pa · s to 1500 Pa · s.   9. The wheel bearing device with a rotational speed detection device according to claim 8, wherein the thermoplastic resin includes one or more compounds selected from the group consisting of polyamide 12, polyamide 612, polyamide 11, and polyphenylene sulfide.   The bearing device for a wheel with a rotation speed detection device according to claim 8 or 9, wherein the magnetic powder is a ferrite magnetic powder.   The wheel bearing device with a rotational speed detection device according to claim 10, wherein the magnetic powder is an anisotropic ferrite magnetic powder.   12. The wheel bearing device with a rotation speed detection device according to claim 8, wherein the magnetic encoder is formed by injection molding of a magnet to be detected.   13. The wheel bearing device with a rotation speed detection device according to claim 12, wherein the magnet of the magnetic encoder is formed by magnetic field molding in injection molding.

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