JP2012073139A - Wheel bearing device equipped with rotational speed detector, and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wheel bearing device equipped with a rotational speed detector in which the sensor of the rotational speed detection device is highly accurately positioned and fixed and, further, the sensor is protected and the airtightness of the sensor and a sensor holder can be secured, and to provide a manufacturing method of the same.SOLUTION: The wheel bearing device includes: an annular encoder 20 which is fittingly attached to the circumference near the inboard side end of an inner member 2 and whose characteristic changes along the circumferential direction; a toric sensor holder 22 opposing the encoder 20 and fittingly attached to the end of an outer member 1; a sensor 21 embedded in the sensor holder 22 and opposing the encoder 20 via a gap and detecting the encoder 20; and a sealing device 24 located on the inboard side from the sensor 21 and sealing between the sensor holder 22 and the inner member 2. The sensor 21 is molded integrally with the toric sensor holder 22 by hot melt molding using a hot melt type resin.

Description

  The present invention relates to a wheel bearing device having a built-in rotational speed detection device for a bearing portion that rotates relative to an antilock brake system of an automobile, and a method for manufacturing the same.

  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. And a method of manufacturing the same.

  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 attached to the outer periphery in the vicinity of the inboard side end of the side member and whose characteristics change along the circumferential direction, and a fitted state at the end of the outer member facing the encoder An annular sensor holder attached to the sensor, a sensor embedded in the sensor holder and opposed to the encoder through a gap, and detecting the encoder; and the sensor holder and the sensor positioned on the inboard side of the sensor Close to the inner member A sealing device provided for the sensor, characterized in that it is integrally molded on the annular sensor holder by a hot-melt molding using a hot-melt type resin.

  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.

The encoder may be provided with a conical inclined surface with respect to the axial direction, and the annular sensor holder may be attached to the end of the outer member so as to face the conical inclined surface with respect to the encoder axial direction. .
Since a sealing device for sealing between the sensor holder and the inner member is provided, and further, an encoder having a conical slope and an annular sensor holder facing the conical slope are provided. It is possible to more reliably prevent the encoder from being worn out by foreign matter or the like from the outside. Thereby, accurate rotation detection is possible. In addition, since the encoder has a conical slope as a surface to be detected, a cross section viewed by cutting the encoder along a plane along the bearing axial direction can be made into a triangular shape, and the structure can be strengthened. Furthermore, since the detection surface of the encoder is a conical slope, the encoder is arranged at the same axial position as the sensor holder. 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 fitted and fixed in a hole provided on a surface of the sensor holder facing the encoder, and may be integrally molded with the sensor holder.
In this case, since the sensor is fitted and fixed in advance, the sensor position in the mold can be easily managed at the time of molding, and the molding cost can be reduced.

  The sensor may be fitted and fixed in a hole provided in a conical slope facing the encoder in the sensor holder, and may be integrally molded with the sensor holder. Also in this case, the sensor position in the mold can be easily managed at the time of molding, and the molding cost can be reduced.

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.

In the magnetic encoder, the magnet to be detected may be a plastic magnet, and the plastic magnet may be 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.

The method of manufacturing a wheel bearing device with a rotational speed detection device according to the present invention includes an outer member that forms a double-row rolling surface on the inner periphery and serves as a stationary member, and a rolling surface that faces each of the rolling surfaces. Of a bearing device for a wheel that includes an inner member that is formed on the outer periphery and serves as a rotation-side member, and a double-row rolling element that is interposed between the opposing rolling surfaces, and that rotatably supports the wheel with respect to the vehicle body. In the manufacturing method, an annular encoder that is fitted in an outer periphery near the inboard side end of the inner member and has a characteristic change along a circumferential direction, and the outer member facing the encoder An annular sensor holder that is fitted to the end portion, a sensor that is embedded in the sensor holder and that faces the encoder through a gap, detects the encoder, and is located on the inboard side of the sensor. The sensor holder and the front A sealing device for sealing between the inner member and the sensor, wherein the sensor and the sensor holder include a hole for fitting and fixing the sensor by injecting molten hot-melt resin into a cavity in the mold. A process of forming a sensor holder, and a process of fitting and fixing the sensor in the hole of the sensor holder after the process and integrally molding the sensor on the sensor holder by hot melt molding.
In this case, compared to general injection molding, the manufacturing equipment can be made lower in both heat resistance and pressure resistance, and the cost required for the manufacturing equipment can be kept low. Furthermore, the pressure on the sensor during molding can be relieved, and the temperature at the time of molding can be set to, for example, a sensor operation guarantee temperature or lower. In addition, since the hot-melt resin has good adhesiveness, it can ensure good airtightness between the sensor and the sensor holder. Since the sensor is fitted and fixed in the hole of the sensor holder, the sensor can be easily and accurately positioned with respect to the sensor holder.

  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 attached to the outer periphery in the vicinity of the inboard side end of the side member and whose characteristics change along the circumferential direction, and a fitted state at the end of the outer member facing the encoder An annular sensor holder attached to the sensor, a sensor embedded in the sensor holder and opposed to the encoder through a gap, and detecting the encoder; and the sensor holder and the sensor positioned on the inboard side of the sensor Close to the inner member The sensor is integrally molded with the annular sensor holder by hot melt molding using a hot melt resin, so that the sensor of the rotational speed detection device can be positioned and fixed with high accuracy. In addition, the sensor can be protected and airtightness between the sensor and the sensor holder can be secured.

  The method of manufacturing a wheel bearing device with a rotational speed detection device according to the present invention includes an outer member that forms a double-row rolling surface on the inner periphery and serves as a stationary member, and a rolling surface that faces each of the rolling surfaces. Of a bearing device for a wheel that includes an inner member that is formed on the outer periphery and serves as a rotation-side member, and a double-row rolling element that is interposed between the opposing rolling surfaces, and that rotatably supports the wheel with respect to the vehicle body. In the manufacturing method, an annular encoder that is fitted in an outer periphery near the inboard side end of the inner member and has a characteristic change along a circumferential direction, and the outer member facing the encoder An annular sensor holder that is fitted to the end portion, a sensor that is embedded in the sensor holder and that faces the encoder through a gap, detects the encoder, and is located on the inboard side of the sensor. The sensor holder and the front A sealing device for sealing between the inner member and the sensor, wherein the sensor and the sensor holder include a hole for fitting and fixing the sensor by injecting molten hot-melt resin into a cavity in the mold. A rotation speed detecting device includes a process of forming a sensor holder, and a process of fitting and fixing a sensor in the hole of the sensor holder after the process, and integrally molding the sensor in the sensor holder by hot melt molding. It is possible to position and fix the sensor 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 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 part of the said hole. It is an expanded sectional view of the important section of the wheel bearing device concerning other embodiments of this invention. It is an expanded sectional view of the principal part of the bearing device for wheels concerning other embodiments of this invention.

  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 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 protrusion 20ba is provided in the vicinity of the base end of the outward surface of the upright plate portion 20b, and is fitted to the outer peripheral surface of the end portion of the first seal plate 25 of the sealing device 24.

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 melt viscosity of the thermoplastic resin in this case is, for example, a capillograph (manufactured by Toyo Seiki Co., Ltd.), using a capillary with a diameter of 1 mmφ and a land length of 10 mm, a shear rate of 100 (l / s), and a thermoplastic resin The result measured at the temperature of melting | fusing point +50 degreeC is shown.

  The thermoplastic resin in this case is composed of polyamide 12, polyamide 612, polyamide 11 and poniphenylene sulfide which have a very small expansion amount (10% or less) even when immersed in grease used as a lubricant in a bearing at a high temperature. It is preferred to include one or more compounds selected from the group. Since these thermoplastic resins have poor water absorption, they are resistant to deterioration even under high moisture conditions such as dew condensation at low temperatures, salt water, muddy water, rain water, etc., and are particularly suitable as materials for the encoder 20 incorporated in the wheel bearing device. It is valid.

  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 described above, the sensor holder 22 is attached to the outer member 1, and the sensor 21 embedded in the sensor holder 22 is positioned on the bearing inner side of the upright plate portion 20 b of the encoder 20 and the upright plate portion 20 b. And facing in the axial direction through a predetermined 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. In a state where the outer diameter cylindrical portion 26a of the cored bar 26 is press-fitted into the outer peripheral surface of the outer member 1, and the flange portion 26b is in close contact with the inboard side end surface of the outer member 1, the sensor holder 22 is in the outer member 1. It is fixed to the end of the inboard side.
The sensor 21 is integrally molded with the annular sensor holder 22 by hot melt molding using a hot melt type resin (referred to as “hot melt resin”). “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 that protrude a predetermined distance radially inward from a plurality of perforations 28 in the circumferential direction of the inner diameter cylindrical portion 26c. It should be noted that the actual height of the outer diameter edge of the encoder 20 is lower than the perforation 28, that is, a position on the radially inner side. The sensor 21 is integrally molded with the sensor embedding protrusion 27a by hot melt molding.
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. 4A, after the mold 31 having the upper mold 29 and the lower mold 30 is clamped, the molten hot-melt resin is injected into the cavity 32 in the mold 31 with a predetermined injection pressure. Inject. 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, a hole 33 for positioning and holding the sensor 21 is formed in the sensor embedded protrusion 27 a of the sensor holding body 27. The holes 33 are defined according to the dimensions of the sensor 21 to be employed, and are provided, for example, at a plurality of locations in the circumferential direction of the sensor holder 27. The plurality of holes 33 are formed at equal distances from the axial center of the sensor holding body 27 in the radial direction, and each hole 33 is, for example, a bottomed cylinder corresponding to the outer diameter and thickness of the cylindrical sensor 21. It is formed in a shape.
After the injected hot melt resin is cured, as shown in FIG. 4B, the upper mold and the lower mold 30 are opened, and the sensor 21 is fitted and fixed in the hole 33 of the sensor embedding protrusion 27a. In this case, the outer peripheral surface of the sensor 21 is fitted into the inner peripheral surface of the hole 33 while the bottom surface of the sensor 21 is placed and supported on the bottom of the hole 33. After that, as shown in FIG. 4C, the mold 21 is clamped again and the opening 33a of the hole 33 is closed with hot melt resin, so that the sensor 21 is embedded in the sensor holder 22 as shown in FIG. . After the sensor holder 22 is assembled to the metal core 26, the outer diameter cylindrical portion 26 a of the metal core 26 is press-fitted into the outer peripheral surface of the outer member 1. In addition, in a state where the main part of the core metal 26 is positioned in the cavity 32 in the mold 31, a molten hot melt resin may be injected into the cavity 32.

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.

  In addition, the sensor 21 is integrally molded with the annular sensor holder 22 by hot melt molding using hot melt resin. 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 aluminum or the like, and the production cost of the mold can be kept lower than that of a 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 molding is performed in a low temperature / low pressure environment, the pressure applied to the sensor 21 during molding can be reduced, and the temperature at the time of molding can be set to, for example, the operation guarantee temperature of the sensor 21 or less. Therefore, the possibility that the sensor 21 is damaged is reduced, and the yield is improved. Moreover, since hot-melt resin has favorable adhesiveness, airtightness with the sensor 21 and the sensor holder 22 can be ensured favorable. Therefore, the hole of the sensor holder 22 and the like 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 a hole 33 provided on the surface of the sensor holder 22 facing the encoder 20 and is integrally molded with the sensor holder 22, the sensor position in the mold 31 can be managed at the time of molding. It becomes easy and the molding cost can be reduced.

  Another embodiment of the present invention will be described. In the following description, the same reference numerals are given to portions corresponding to the matters described in the preceding forms in each embodiment, and overlapping description may be omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described in the preceding section. Not only the combination of the parts specifically described in each embodiment, but also the embodiments can be partially combined as long as the combination does not hinder.

5A, the encoder 20A is inclined with respect to the axial direction so that the inner peripheral surface 20Aa that is press-fitted into the outer peripheral surface of the inner member 2 and fixed, and the bearing inside has a large diameter. A single annular multipolar magnet having an inclined surface 20Ab as an outer peripheral surface is used. 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 36a provided in the inclined surface 36 facing the inclined surface 20Ab of the encoder 20A in the sensor embedded protrusion 27Aa. Then, the sensor 21 is embedded in the sensor holder 22 by closing the opening of the hole 36a with hot melt resin.

  The inclined surface 20Ab of the encoder 20A, the inclined surface 36 of the sensor embedding protrusion 27Aa, and the sealing device 24 prevent foreign matter from entering from the outside, and can more reliably prevent the encoder 20A from being worn. Since the encoder 20A has a conical inclined surface 20Ab as a surface to be detected, a cross section of the encoder 20A cut by a plane along the bearing axis direction can be made into a triangular shape, thereby strengthening the structure. it can. In addition, a sensor embedded protrusion 27Aa of the encoder 20A is disposed at the same axial position as the sensor holder 22. Therefore, the axial length of the entire wheel bearing device can be shortened by the axial length of the encoder 20A, and the device can be made compact. Since the sensor 21 is fitted and fixed in the hole 36a, the position of the sensor in the mold can be easily managed during molding, and the molding cost can be reduced. In addition, the same operational effects as the embodiment of FIG.

  In the example of FIG. 6, a hole 37 for fitting and fixing the sensor 21 is formed in the core metal 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 37 of the cored bar 26. In this case, 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 holding body. Therefore, the manufacturing cost can be reduced as compared with those shown in FIGS.

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 in the case of using such a plastic magnetic encoder, in particular, by using the structure of FIG. 5, that is, the sealing device 24, the conical inclined surface 36, and the inclined surface 20Ab, foreign matter and the like enter from the outside of the bearing. This prevents the wear of the plastic magnetic encoder more reliably. 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.

DESCRIPTION OF SYMBOLS 1 ... Outer member 2 ... Inner member 3 ... Rolling element 4, 5 ... Rolling surface 20 ... Encoder 21 ... Sensor 22 ... Sensor holder 23, 23A ... Rotation speed detection apparatus

Claims (14)

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 whose characteristics change 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 embedded in the sensor holder and opposed to the encoder via a gap to detect the encoder;
A sealing device that is located on the inboard side of the sensor and seals between the sensor holder and the inner member;
A wheel bearing device with a rotational speed detecting device, wherein the sensor is integrally molded with the annular sensor holder by hot melt molding using a hot melt type resin.   2. The end of the outer member according to claim 1, wherein the encoder has a conical inclined surface with respect to the axial direction, and the annular sensor holder faces the conical inclined surface with respect to the encoder axial direction. Wheel bearing device with attached rotation speed detection device.   The wheel bearing device with a rotation speed detecting device according to claim 1, wherein the sensor is fitted and fixed in a hole provided on a surface of the sensor holder facing the encoder, and is integrally molded with the sensor holder.   The wheel with a rotational speed detection device according to claim 1 or 2, wherein the sensor is fitted and fixed in a hole provided in a conical slope facing the encoder in the sensor holder, and is integrally molded with the sensor holder. 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 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 with a rotational speed detection device according to claim 8, wherein the magnet to be detected is a plastic magnet, and the plastic magnet is formed by injection molding. Bearing device.   13. The wheel bearing device with a rotation speed detection device according to claim 12, wherein the plastic magnet of the magnetic encoder is formed by magnetic field molding in injection molding. 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 In a manufacturing method of a wheel bearing device that includes a double row rolling element interposed between the rolling surfaces to support the wheel rotatably with respect to the vehicle body,
An annular encoder that is fitted to the outer periphery of the inner member near the inboard side end and whose characteristics change along the circumferential direction, and is fitted to the end of the outer member facing the encoder. An annular sensor holder mounted in a combined state, a sensor embedded in the sensor holder and opposed to the encoder through a gap to detect the encoder, and the sensor holder located on the inboard side of the sensor And a sealing device for sealing between the inner member and the inner member,
The sensor and sensor holder are:
A process of forming a sensor holder including a hole for injecting molten hot melt resin into a cavity in a mold and fitting and fixing the sensor;
After the process, a process of fitting and fixing a sensor in the hole of the sensor holder, and molding the sensor integrally with the sensor holder by hot melt molding;
The manufacturing method of the wheel bearing apparatus with a rotational speed detection apparatus characterized by having.

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