Bearing device

Abstract

To provide a bearing device for wheels, which is excellent in water resistance, good in assemblability in a simple construction, and equipped with a power generator and a wireless communication function.SOLUTION: A bearing device 1 includes a bearing part B, a magnetic ring 12, a bearing cap 11, a stator 17, and a circuit board 18, the bearing cap 11 serving for closing the opening end on the inner side of an outward member 6, the stator 17 being fixed to the inner face of the bearing cap 11 so as to be opposed to the magnetic ring 12 to form a power generator G together with the magnetic ring 12, the circuit board 18 being fixed to the inner face of the bearing cap 11, the circuit board 18 including a power supply circuit 23 for rectifying AC voltage of the power generator G, sensors 24, 25 for monitoring the state of the bearing part B, and a wireless communication circuit 26 for wirelessly transmitting the output of the sensors 24, 25 to the outside.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a bearing device.

Background Art

[0002] There is known a bearing device for a wheel in which a generator, a sensor, and a wireless communication circuit are mounted on a wheel bearing, and a sensor signal is wirelessly transmitted.

[0003] In the rotational speed detection device for a wheel described in Japanese Patent Application Laid-Open No. 2003-146196 (Patent Document 1), an encoder made of a magnetic metal plate in which slit-shaped through holes are formed at equal intervals is fixed to a hub (inner ring). This rotational speed detection device is equipped with a passive type generator that generates electricity as the encoder rotates. The generator includes an annular permanent magnet magnetized in the radial direction, a yoke formed by shaping the magnetic metal plate into an annular shape, and a coil disposed in a portion surrounded by the yoke and the permanent magnet.

[0004] In this rotational speed detection device for a wheel, the generator and the rotation detection sensor are used in common. As the encoder rotates, an AC voltage is output across both ends of the coil. Using this voltage, it is converted into a DC voltage by a processing circuit to drive a transmission circuit, and a rotational speed signal of the hub and the inner ring is wirelessly transmitted to a controller provided on the vehicle body side.

[0005] The rolling bearing unit for wheel support described in Japanese Patent No. 6516077 (Patent Document 2) includes a bearing portion that supports a driven wheel (wheel) of an automobile, a generator having a power generation function, a wireless communicator having a wireless communication function, a battery having a power storage function, an interface circuit that processes a sensor signal, and a connector.

[0006] The bearing section comprises an outer ring, a hub, and multiple rolling elements. A generator and a wireless communication device are positioned axially inward of the hub. Meanwhile, a battery, interface circuit, and connector are positioned inside the outer recess of the hub. The generator and wireless communication device are electrically connected to the battery, interface circuit, and connector by wiring that passes through through holes provided in the bulkhead of the hub. The wheel support rolling bearing unit temporarily stores the power generated by the generator in the battery, then supplies it to the wireless communication device and interface circuit, and also supplies it to sensors installed on the wheel side (tire-side sensor, wheel-side sensor) via the connector. The wheel support rolling bearing unit transmits the sensor output signals to the interface circuit via the connector and wirelessly transmits them to a computer located on the vehicle body side via the wireless communication device. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2003-146196 [Patent Document 2] Patent No. 6516077 [Patent Document 3] Japanese Patent Publication No. 2021-09915 [Patent Document 4] Japanese Patent Publication No. 2005-282766 [Patent Document 5] Japanese Patent Publication No. 2018-54095 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the wheel rotation speed detection device described in Japanese Patent Publication No. 2003-146196 (Patent Document 1), the open end of a cover, which is formed into a cylindrical shape with a bottom surface by plastically deforming a magnetic metal plate, is fitted into the inner end opening of the outer ring, thereby closing the inner end opening of the outer ring. However, in this device, the sensor unit is held in a sealed state in a through hole formed in a part of the bottom plate of the cover, but it is conceivable that moisture may enter through the gap.

[0009] The wheel support rolling bearing unit described in Japanese Patent Publication No. 6516077 (Patent Document 2) has a fixed cylindrical section mounted in an inner recess provided in the center of the hub, and electrical components (circuit boards) such as wireless communication devices are housed inside, which requires additional machining of the hub. Furthermore, the complex shape and large number of parts make assembly difficult. In addition, it is difficult to increase the size of the circuit board for mounting wireless communication devices and interface circuits, making component mounting a challenge.

[0010] This disclosure is made to solve the above-mentioned problems, and its purpose is to provide a wheel bearing device equipped with a generator and wireless communication function that has excellent water resistance, sufficient substrate space, eliminates the need for additional machining of the hub, has a simple structure and is easy to assemble. [Means for solving the problem]

[0011] This disclosure relates to a wheel bearing device for rotatably supporting a wheel. The bearing device comprises an outer member having double rows of outer raceway surfaces on its inner circumference, an inner member having double rows of inner raceway surfaces facing each of the double rows of outer raceway surfaces, and double rows of rolling elements housed rotatably between the raceway surfaces of the outer member and the inner member. Each of the double rows of rolling elements includes a plurality of rolling elements. The bearing device further comprises a magnetic ring fixed to the inner member and magnetized alternately with north and south poles, a bearing cap attached to the outer member and closing the open end of the outer member on the vehicle body side, a stator fixed to the inner surface of the bearing cap so as to face the magnetic ring and forming a generator together with the magnetic ring, and a circuit board fixed to the inner surface of the bearing cap. The circuit board includes a power supply circuit for rectifying the AC voltage of the generator, a sensor for monitoring the state of the bearing device, and a wireless communication circuit for wirelessly transmitting the output of the sensor to the outside. [Effects of the Invention]

[0012] According to the bearing device of this disclosure, the stator and circuit board are fixed to the bearing cap. Therefore, machining or other processes for fixing them to the outer member are unnecessary, and assembly is simplified. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional side view showing the overall configuration of the bearing device according to Embodiment 1. [Figure 2] This is an enlarged view of section A in Figure 1. [Figure 3] This is a front view of the back surface of the bearing cap in the III-III section of Figure 1. [Figure 4] This is a cross-sectional view of the generator's magnetic ring and stator, unfolded in a straight line. [Figure 5] This is a cross-sectional side view showing the overall configuration of the bearing device according to Embodiment 2. [Figure 6] This is an enlarged view of section B in Figure 5. [Figure 7] This is a front view of the back of the bearing cap as seen from VII-VII in Figure 5. [Figure 8]This is a diagram showing a state in which two magnetic ring members are arranged opposite to each other. [Figure 9] This is a diagram showing a state in which two magnetic ring members 32-1 and 32-2 are fitted together.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

[0015] [Embodiment 1] FIG. 1 is a cross-sectional side view showing the overall configuration of the bearing device according to Embodiment 1.

[0016] In this specification, for convenience, the description will be based on the outer side and the inner side defined by the direction of the arrow shown in FIG. 1. Here, the "outer side" means the direction on the wheel side that is rotatably supported by the bearing device 1 with respect to the bearing device 1 in a state of being attached to a vehicle body such as an automobile. The "inner side" means the direction opposite to the outer side, that is, the inner side of the vehicle body, with respect to the bearing device 1 in a state of being attached to a vehicle body such as an automobile.

[0017] Also, in this specification, the direction parallel to the rotation center axis R (see FIG. 1) of the bearing device 1 is defined as the "axial direction", the direction orthogonal to the rotation center axis R of the bearing device 1 is defined as the "radial direction", and the direction along an arc centered on the rotation center axis R of the bearing device 1 is defined as the "circumferential direction" for description.

[0018] First, the overall configuration of the bearing device 1 in the present embodiment will be described using FIG. 1. The bearing device 1 is what is called the third generation for a driven wheel as also described in Patent Documents 3 to 5, and has an inner member 4 having a hub ring 2 and an inner ring 3, and a bearing portion B including an outer member 6 externally inserted into the inner member 4 via a double row of rolling elements (balls) 5a and 5b.

[0019] A wheel mounting flange 7 for attaching a wheel (not shown) is integrally formed on the outer end of the hub wheel 2. Multiple bolt holes 7a are arranged at equal intervals along the circumferential direction in the wheel mounting flange 7. The bolt holes 7a are for fixing hub bolts (not shown) that fasten the wheel or the like to the hub wheel 2.

[0020] The outer circumference of the hub ring 2 has an inner raceway surface 2a on one side (the outer side) and a cylindrical small-diameter stepped portion 2b extending inward from the inner raceway surface 2a. An inner ring 3, having the other (inner side) inner raceway surface 3a on its outer circumference, is press-fitted into the small-diameter stepped portion 2b of the hub ring 2. A crimped portion 2c is formed at the end of the small-diameter stepped portion 2b, which is plastically deformed radially outward. The crimped portion 2c fixes the axial position of the inner ring 3 relative to the hub ring 2 while a predetermined bearing preload is applied.

[0021] The outer member 6 has a body mounting flange 9 integrally formed on its outer circumference for attachment to a knuckle (not shown). The outer member 6 has double rows of outer raceway surfaces 6a and 6b formed on its inner circumference, opposite to the double rows of inner raceway surfaces 2a and 3a.

[0022] Between the two outer raceway surfaces 6a and 6b of the outer member 6 and the double rows of inner raceway surfaces 2a and 3a facing these outer raceway surfaces 6a and 6b, two rows of rolling elements 5a and 5b are housed. Each of the rolling elements 5a and 5b is held to roll freely by a retainer 8.

[0023] Furthermore, a cylindrical synthetic resin bearing cap 11 with a bottom surface is fitted to the inner opening end of the outer member 6. The bearing cap 11 closes the inner opening of the outer member 6, preventing rainwater or dust from entering the inside of the bearing device 1 from the outside.

[0024] Figure 2 is an enlarged view of section A in Figure 1. Referring to Figures 1 and 2, the magnetic ring 12 is fitted onto the outer diameter of the inner ring 3 from the outside. The magnetic ring 12 is composed of a ring-shaped support ring 13 and a multipole magnet 14 that is vulcanized and bonded to the side surface of the support ring 13.

[0025] Furthermore, the multipole magnet 14 is made of an elastomer such as rubber mixed with magnetic powder such as ferrite. The multipole magnet 14 has magnetic north poles and south poles magnetized alternately and at equal intervals in the circumferential direction.

[0026] The support ring 13 is formed, for example, by press-forming a ferromagnetic steel plate so that its cross-section is substantially L-shaped. The support ring 13 has a cylindrical fitting portion 13a that fits onto the inner ring 3, and a vertical plate portion 13b that extends radially inward from the inner end of the fitting portion 13a. A multipole magnet 14 is joined to the inner surface of the vertical plate portion 13b.

[0027] As described above, the bearing cap 11 is fitted and fixed inside the inner opening end of the outer member 6, closing the opening of the outer member 6. The bearing cap 11 comprises a cylindrical cap body 15 with a bottom surface. Further details regarding the configuration of the bearing cap 11 will be described later.

[0028] As described above, the bearing device 1 in this embodiment is a bearing device for a driven wheel, and is exemplified as a wheel bearing device composed of a double-row angular contact ball bearing using balls for the rolling elements 5a and 5b. However, the bearing device is not limited to this, and may be composed of a double-row tapered roller bearing using tapered rollers for the rolling elements.

[0029] Furthermore, while a third-generation structure was given as an example, the structure is not limited to this. Next, the detailed configuration of the bearing cap 11 in this embodiment will be described with reference to Figures 1 and 2.

[0030] As shown in Figure 1, the bearing cap 11 is composed of a cylindrical cap body 15 having a bottom surface made by injection molding of synthetic resin, and a core metal 16 integrally molded into the opening of the cap body 15.

[0031] Although the synthetic resin cap body 15 may be directly attached to the outer member 6 without providing the core metal 16, providing the core metal 16 increases the strength and rigidity of the bearing cap 11, thereby improving its resistance to coming loose. In addition, since the fitting portion 15a is made of elastic resin, the airtightness of the fitting portion is improved.

[0032] The cap body 15 is formed by injection molding. The cap body 15 is formed by adding a fibrous reinforcing material such as glass fiber to a non-magnetic special ether-based synthetic resin material such as polyphenylene sulfide (PPS).

[0033] On the other hand, the core metal 16 is formed in an L-shaped annular form by press-forming, for example, a stainless steel sheet or a cold-rolled steel sheet.

[0034] The cap body 15 comprises a cylindrical fitting portion 15a that fits onto the inner circumference of the inner end of the outer member 6, a flange portion 15b provided radially outward of the fitting portion 15a and in contact with the inner end surface of the outer member 6, and a flat bottom portion 15c provided radially inward of the flange portion 15b.

[0035] In this specification, the inner surface of the bearing cap 11 includes the inner diameter surface of the cylindrical portion consisting of the fitting portion 15a, the flange portion 15b, and the core metal 16, and the inner surface of the bottom portion 15c.

[0036] Figure 3 is a front view of the back surface of the bearing cap in the III-III section of Figure 1. A stator 17 and a circuit board 18 are fixed to the inner surface 15d of the bottom surface 15c of the cap body 15. The stator 17 is fixed so as to face the magnetic ring 12. The magnetic ring 12 and the stator 17 constitute the generator G.

[0037] The stator 17 includes a magnetic yoke, a bobbin 21, and a coil 22. The magnetic yoke consists of a magnetic base member 19 made of a fan-shaped magnetic material and a magnetic pin member 20 made of a magnetic material fixed to protrude from the magnetic base member 19. The magnetic pin member 20 is fixed to a hole 19a formed in the magnetic base member 19 by press-fitting or adhesive.

[0038] Multiple windings of the coil 22 are wound around the circumference of the bobbin 21. While this example shows the use of a bobbin 21, a stator can be constructed similarly using a coil without a bobbin 21.

[0039] Here, the magnetic pin member 20 is cylindrical, but it may also be a rectangular prism. Alternatively, the magnetic pin member 20 may be fixed to the magnetic base member 19 by adhesive or welding without providing the hole 19a, or the magnetic base member 19 and the magnetic pin member 20 may be molded as a single unit.

[0040] The stator 17 is fixed to the inner surface 15d of the cap body 15 by screws or adhesive. In the case of screw fixing, a nut (not shown) is insert-molded into the cap body 15.

[0041] Figure 4 is a cross-sectional view of the generator's magnetic ring and stator unfolded in a straight line. As shown in Figure 4, the magnetic flux emanating from the north pole of the multipole magnet 14 enters the magnetic base member 19 from the magnetic pin member 20, which is a magnetic pole, and enters the south pole of the multipole magnet 14 from the adjacent magnetic pin member 20. When the positions of the north and south poles of the multipole magnet 14 are swapped due to the rotation angle of the hub wheel 2, the direction of the magnetic flux is reversed. The alternating magnetic field generated in this way generates an alternating voltage across the coil 22. The output (alternating voltage) of the generator G is rectified by the power supply circuit 23 mounted on the circuit board 18 and used as a power source for the sensor and wireless communication circuit 26.

[0042] As shown in Figure 3, the circuit board 18 is equipped with a power supply circuit 23 that rectifies the AC voltage of the generator G, and a wireless communication circuit 26 that wirelessly transmits the output of sensors (accelerometer 24, temperature sensor 25) that monitor the status of the bearing device 1 to the outside.

[0043] The battery 27 may be mounted on the circuit board 18. By mounting the battery 27 in the center of the circuit board 18 and positioning it so as to penetrate the hollow hole 12a of the magnetic ring 12, a tall battery 27 can be used. In Figure 3, a small battery 27 that fits within the space is selected and multiple batteries 27 are connected in parallel to secure the required battery capacity, but a single large-capacity battery 27 may also be used.

[0044] By mounting the battery 27 on the circuit board 18, surplus power can be charged to the battery 27 while the wheels (not shown) are rotating and the generator G is generating power. In this case, even when the wheels stop rotating and the generator G stops generating power, the power from the battery 27 can be used to wirelessly transmit the sensor output to the outside.

[0045] The circuit board 18 is fixed to the inner surface 15d of the cap body 15 with screws or adhesive. In the case of screw fixing, a nut (not shown) is inserted into the cap body 15.

[0046] The rotational speed can be determined by generating a pulse waveform from the AC voltage generated across the coil 22 of the generator G and measuring the number of pulses per unit time, or by measuring the elapsed time from the rising (or falling) edge of one pulse to the rising (or falling) edge of the next pulse. Alternatively, a magnetic sensor (Hall element or Hall IC) not shown in the diagram may be mounted on the circuit board 18, and the rotational speed may be determined by detecting the switching of the poles of the multi-pole magnet 14.

[0047] The stator 17 of the generator G and the circuit board 18 are fixed to the bearing cap 11, and at least the power supply circuit 23, sensors (24, 25), and wireless communication circuit 26 are mounted on the circuit board 18.

[0048] As described above, a magnetic ring 12, which is magnetized alternately with north and south poles in the circumferential direction, is fixed to one end of the inner ring 3 of the bearing section B. The magnetic ring 12 may also be fixed to one end of the inner member 4. The bearing cap 11 that closes the inner end opening of the outer member 6 (outer ring) has a cylindrical shape with a bottom surface having a bottom surface portion 15c, and the bottom surface portion 15c is made of resin.

[0049] The stator 17 and circuit board 18 of the generator G are fixed to the inner surface 15d (the surface facing the outer side) of the bottom surface 15c of the bearing cap 11. The stator 17 faces the multipole magnet 14 of the magnetic ring 12, which is fitted and fixed to the inner ring 3, with a gap between them.

[0050] The stator 17 and the circuit board 18 are protected by a encapsulant (resin molding agent) not shown. The filling height M of the encapsulant is set so as not to come into contact with the magnetic ring 12. (See Figure 1) By press-fitting and fixing the bearing cap 11 into the inner end opening of the outer member 6, the stator 17 and the multipole magnets 14 of the magnetic ring 12 face each other with a certain gap, making assembly easy. Furthermore, the circuit board 18 on which the wireless communication circuit 26 is mounted is fixed to the synthetic resin bearing cap 11. Since at least the bottom surface 15c of the bearing cap 11 is made of resin, radio waves can be transmitted from the antenna of the wireless communication circuit 26 to the outside of the bearing cap 11.

[0051] Furthermore, since there is no need to drill holes for wireless communication in the bearing cap 11, and the inner end opening of the outer member 6 can be securely closed with the bearing cap 11, water resistance is ensured and foreign matter can be prevented from entering from the outside.

[0052] Furthermore, because the stator 17 and circuit board 18 are fixed to the bearing cap 11, machining is not required to fix them to the outer member 6. This also simplifies assembly.

[0053] [Embodiment 2] Figure 5 is a cross-sectional side view showing the overall configuration of the bearing device according to Embodiment 2. Figure 6 is an enlarged view of section B in Figure 5. Figure 7 is a front view of the back of the bearing cap as seen from VII-VII in Figure 5.

[0054] The configuration of bearing device 1A shown in Figure 5 is the same as that of bearing device 1 shown in Figure 1, but with generator GA instead of generator G.

[0055] A magnetic ring 28 is fitted onto the outer diameter of the inner ring 3 of the bearing device 1A. The magnetic ring 28 consists of a ring-shaped support ring 29 and a multi-pole magnet 30 that is vulcanized and bonded to the outer circumference of the support ring 29.

[0056] Furthermore, the multipole magnet 30 is made of an elastomer such as rubber mixed with magnetic powder such as ferrite. The multipole magnet 30 has magnetic poles, north and south, magnetized alternately and at equal intervals in the circumferential direction.

[0057] The support ring 29 is formed, for example, by press-forming a ferromagnetic steel plate to create a substantially L-shaped cross-section. The support ring 29 has a cylindrical fitting portion 29a that fits onto the inner ring 3, and a vertical plate portion 29b that extends radially inward from the inner end of the fitting portion 29a. A multipole magnet 30 is joined to the outer circumference of the fitting portion 29a.

[0058] The stator 31 and the circuit board 35 are fixed to the bearing cap 11A. In this specification, the inner surface of the bearing cap 11A includes the inner diameter surface of the cylindrical portion consisting of the fitting portion 15a, the flange portion 15b, and the core metal 16, and the inner surface of the bottom portion 15c. The stator 31 is fitted and fixed to the inner diameter surface of the core metal 16, which is the inner surface of the bearing cap 11A, so as to face the multipole magnets 30 of the magnetic ring 28.

[0059] The circuit board 35 is equipped with a power supply circuit 23 that rectifies the AC voltage of the generator GA, and a wireless communication circuit 26 that wirelessly transmits the output of sensors (accelerometer 24, temperature sensor 25) that monitor the status of the bearing device 1A to the outside.

[0060] The battery 27 may be mounted on the circuit board 18. The battery 27 is mounted in a position that does not interfere with the crimping portion 2c of the inner member 4 or the magnetic ring 28.

[0061] The circuit board 35 is fixed to the bottom surface 15c (outer side) of the cap body 15 with screws or adhesive. In the case of screw fixing, a nut (not shown) is insert-molded into the cap body 15.

[0062] The circuit board 35 is protected by a encapsulant (resin molding agent) not shown. The filling height M of the encapsulant is set so as not to come into contact with the magnetic ring 12. (See Figure 5) The generator GA is composed of a magnetic ring 28 and a stator 31. The generator GA is a claw-pole type generator. The stator 31 is composed of a coil 33 and a magnetic yoke 32 surrounding it. The magnetic yoke 32 is composed of magnetic ring members 32-1 and 32-2.

[0063] Figure 8 shows a configuration in which two magnetic ring members are arranged opposite each other. In reality, a bobbin 34 on which a coil 33 is wound is housed in the space between the two magnetic ring members 32-1 and 32-2, but to avoid making the diagram too complex, the coil 33 and bobbin 34 are omitted from the illustration here.

[0064] At one end of the magnetic ring member 32, grooves 32a and claws 32b that open in the axial direction are arranged alternately in a comb-like pattern.

[0065] Figure 9 shows the state in which two magnetic ring members 32-1 and 32-2 are fitted together. Magnetic ring member 32-1 and magnetic ring member 32-2 have the same shape. The same number of recesses 32c and protrusions 32d are formed on the end faces 32f of magnetic ring members 32-1 and 32-2. The recesses 32c and protrusions 32d provided on the end faces 32f of magnetic ring members 32-1 and 32-2 are fitted together so that the claws 32b provided on each of the magnetic ring members 32-1 and 32-2 are arranged alternately.

[0066] By fitting the recess 32c and the protrusion 32d together so that the end faces 32f come into contact with each other, it becomes easy to align the phase of the arrangement so that the gap between the claws 32b of the magnetic ring member 32-1 and the claws 32b of the magnetic ring member 32-2 is uniform. Furthermore, since multiple recesses 32c and protrusions 32d are arranged in the circumferential direction, the positions of the magnetic ring members 32-1 and 32-2 can be fixed without them shifting in the circumferential direction.

[0067] The end faces 32f of the magnetic ring members 32-1 and 32-2 are in contact with each other without any gaps to form a magnetic path. However, even if a gap occurs, if the core metal 16 of the bearing cap 11A is made of a magnetic material, the core metal 16 can be used as a magnetic path, thus keeping the magnetic resistance of the magnetic yoke low.

[0068] By making the two magnetic ring members 32-1 and 32-2 identical in shape, only one type of mold is needed for press molding. This allows for lower initial manufacturing costs. Furthermore, manufacturing costs can be reduced during the production of the magnetic rings because the number of steps required to change molds is reduced.

[0069] Furthermore, by providing the recess 32c and the protrusion 32d, the phase alignment of the two magnetic ring members 32-1 and 32-2 during assembly becomes easier, and the gaps between each claw 32b can be uniformly arranged, thus simplifying assembly.

[0070] Furthermore, since the recessed portion 32c and the protruding portion 32d provided on the two magnetic ring members 32-1 and 32-2 are fitted together, the two magnetic ring members 32-1 and 32-2 can be easily assembled without adhesive or welding.

[0071] Furthermore, to ensure an even stronger fit, plastic deformation processes such as crimping (not shown) may be added to the fitting portion, or the fitting portion may be elastically deformed. By achieving such a strong fit, the magnetic resistance at the fitting portion of the two magnetic ring members 32-1 and 32-2 is further reduced, thereby improving power generation performance.

[0072] Even in the case of bearing device 1A, the following effects similar to those of bearing device 1 can be obtained. When the bearing cap 11A is press-fitted and fixed into the inner end opening of the outer member 6, the stator 31 and the multipole magnet 30 of the magnetic ring 28 face each other with a certain gap. This makes assembly easy. Furthermore, the circuit board 35 on which the wireless communication circuit 26 is mounted is fixed to the synthetic resin bearing cap 11A. Therefore, radio waves can be transmitted from the antenna of the wireless communication circuit 26 to the outside of the bearing cap 11A without drilling any holes.

[0073] Furthermore, since the inner end opening of the outer member 6 can be closed without drilling a hole for wireless communication in the bearing cap 11A, water resistance is ensured and foreign matter from the outside can be prevented from entering.

[0074] Furthermore, because the stator 31 and circuit board 35 are fixed to the bearing cap 11A, machining is not required to fix them to the outer member 6. This also simplifies assembly.

[0075] (summary) Let us once again refer to the diagram to summarize this embodiment.

[0076] This disclosure relates to a bearing device for rotatably supporting a wheel. The bearing device 1(1A) shown in Figure 1 (Figure 5) comprises a bearing section B(BA). The bearing section B(BA) includes an outer member 6, a hub ring 2 and an inner ring 3, and a plurality of rolling elements 5a, 5b. The plurality of rolling elements 5a, 5b are arranged to roll freely between outer raceway surfaces 6a, 6b and inner raceway surfaces 2a, 3a. The outer member 6 has a double row of outer raceway surfaces on its inner circumference. The outer member 6 has an internal space through which the rotational axis R of the wheel passes, and the outer raceway surfaces 6a, 6b are formed on the inner circumferential surface of the internal space and are installed on the vehicle body. The hub ring 2 and the inner ring 3 constitute the inner member. The inner member has a double row of inner raceway surfaces that are opposite to the double row of outer raceway surfaces. The hub wheel 2 and inner wheel 3 are arranged in the internal space, with inner raceway surfaces 2a and 3a formed on the outer circumferential surface opposite the outer raceway surfaces 6a and 6b, and they rotate together with the wheel. A double row of rolling elements, including multiple rolling elements 5a and 5b, is rotatably housed between the two raceway surfaces of the outer member 6 and the inner member. The bearing device 1(1A) further comprises a magnetic ring 12(28), a bearing cap 11(11A), a stator 17(31), and a circuit board 18(35). The magnetic ring 12(28) is fixed to the inner wheel 3 and is magnetized alternately with north and south poles. The bearing cap 11(11A) is attached to the outer member 6 and closes the open end of the internal space on the vehicle body side. The stator 17(31) is fixed to the inner surface 15d (inner diameter surface of the mandrel 16) of the bearing cap 11(11A) so as to face the magnetic ring 12(28), and together with the magnetic ring 12(28) forms the generator G(GA). The circuit board 18(35) is fixed to the inner surface 15d of the bearing cap 11(11A). The circuit board 18(35) includes a power supply circuit 23 that rectifies the AC voltage of the generator G, sensors 24 and 25 that monitor the state of the bearing section B(BA), and a wireless communication circuit 26 that wirelessly transmits the outputs of the sensors 24 and 25 to the outside.

[0077] In the bearing device 1(1A) shown in Figures 1 and 5, the stator 17(31) of the generator G(GA) and the circuit board 18(35) are fixed to the bearing cap 11(11A), and at least a power supply circuit 23, sensors (24, 25), and a wireless communication circuit 26 are mounted on the circuit board 18(35).

[0078] By press-fitting and fixing the bearing cap 11(11A) into the inner end opening of the outer member 6, the stator 17(31) and the multipole magnet 14(30) of the magnetic ring 12(28) can face each other with a certain gap, making assembly easy. Furthermore, no machining is required to fix these to the outer member 6.

[0079] Preferably, the bearing cap 11(11A) includes a cylindrical portion (core metal 16) and a bottom portion 15c that closes one end of the cylindrical portion (core metal 16). At least the bottom portion 15c of the bearing cap 11(11A) includes a non-metallic member.

[0080] In this way, since the circuit board 18(35) on which the wireless communication circuit 26 is mounted is fixed to the synthetic resin bearing cap 11(11A), radio waves can be transmitted from the antenna of the wireless communication circuit 26 to the outside of the bearing cap 11(11A) without drilling a hole in the bearing cap 11(11A).

[0081] Furthermore, since synthetic resin can allow radio waves to pass through, it eliminates the need to provide an opening for transmitting radio waves, and the inner end opening of the outer member 6 can be securely closed, thus ensuring water resistance and preventing foreign matter from entering from the outside.

[0082] Preferably, the bearing device 1(1A) further comprises a storage battery 27 mounted on the circuit board 18(35). The storage battery 27 is located near the rotation center of the bearing portion B(BA) and is situated in the space between the crimped portion 2c, which is formed by plastically deforming the end of the hub wheel 2, and the circuit board 18.

[0083] Preferably, the bearing cap 11 includes a cylindrical portion (core metal 16) and a bottom portion 15c that closes one end of the cylindrical portion (core metal 16). The stator 17 is fixed to the inner surface 15d of the bottom portion 15c. As shown in Figure 1, the magnetic ring 12 and the stator 17 face each other in a direction parallel to the rotational axis of the bearing portion B.

[0084] More preferably, as shown in Figures 3 and 4, the stator 17 has an arc shape fixed to the bottom surface 15c and faces a part of the ring shape of the magnetic ring 12.

[0085] Preferably, the bearing cap 11A includes a cylindrical portion (core metal 16) and a bottom portion that closes one end of the cylindrical portion (core metal 16). The stator 31 is fixed to the inner diameter surface of the cylindrical portion (core metal 16). As shown in Figure 5, the magnetic ring 28 and the stator 31 face each other in a direction intersecting the rotational axis of the bearing portion BA.

[0086] More preferably, the stator 31 includes a ring-shaped magnetic yoke 32 fixed to the inner diameter surface of the cylindrical portion (core metal 16) and a ring-shaped coil 33 surrounded by the magnetic yoke 32. The generator GA formed by the stator 31 and the magnetic ring 28 is a claw-pole type generator.

[0087] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0088] 1,1A Bearing device, 2 Hub ring, 2a,3a Inner raceway surface, 2b Small diameter step, 2c Crimping part, 3 Inner ring, 4 Inner member, 5a,5b Rolling element, 6 Outer member, 6b Outer raceway surface, 7 Wheel mounting flange, 7a Bolt hole, 8 Cage, 9 Body mounting flange, 11,11A Bearing cap, 12,28 Magnetic ring, 12a Hole hole, 13,29 Support ring, 13a,15a,29a Fitting part, 13b,29b Vertical plate part, 14,30 Multipole magnet, 15 Cap body, 15b Flange part, 15c Bottom surface part, 15d Inner surface, 16 Core metal, 17,31 Stator, 18,35 Circuit board, 19 Magnetic base member, 19a Hole, 20 Magnetic pin member, 21, 34 Bobbin, 22, 33 Coil, 23 Power supply circuit, 24 Acceleration sensor, 25 Temperature sensor, 26 Wireless communication circuit, 27 Storage battery, 32 Magnetic yoke, 32-1, 32-2 Magnetic ring member, 32a Groove, 32b Claw, 32c Recess, 32d Protrusion, 32f End face, B, BA Bearing part, G, GA Generator.

Claims

1. A wheel bearing device, An outer member having double rows of outer raceway surfaces on its inner circumference, An inner member having two rows of inner raceway surfaces facing each of the two rows of outer raceway surfaces, It comprises a double row of rolling elements that are rotatably housed between the raceway surfaces of the outer member and the inner member, Each of the aforementioned double rows of rolling elements includes a plurality of rolling elements, The bearing device is A magnetic ring fixed to the inner member, with alternating N and S poles magnetized, A bearing cap is attached to the outer member and closes the open end of the outer member on the vehicle body side, A stator is fixed to the inner surface of the bearing cap so as to face the magnetic ring, and together with the magnetic ring, forms a generator. The bearing cap further comprises a circuit board fixed to the inner surface of the bearing cap, The aforementioned circuit board is A power supply circuit for rectifying the AC voltage of the generator, A sensor that monitors the status of the bearing device, The system includes a wireless communication circuit that wirelessly transmits the output of the sensor to an external source. The inner member includes a hub ring and an inner ring that rotate together with the wheel. The circuit board further comprises a rechargeable battery mounted on the aforementioned circuit board, The storage battery is located in the bearing device, near the rotation center of the bearing device, in the space sandwiched between a crimped portion formed by plastically deforming the end of the hub ring and the circuit board.

2. The aforementioned bearing cap is The cylindrical part, The cylindrical portion includes a bottom portion that closes one end of the cylindrical portion, The bearing device according to claim 1, wherein at least the bottom surface of the bearing cap includes a non-metallic member.

3. The aforementioned bearing cap is The cylindrical part, The cylindrical portion includes a bottom portion that closes one end of the cylindrical portion, The stator is fixed to the inner surface of the bottom portion, The bearing device according to claim 1, wherein the magnetic ring and the stator face each other in a direction parallel to the rotational axis of the bearing device.

4. The bearing device according to claim 3, wherein the stator has an arc shape fixed to the bottom surface and faces a part of the ring shape of the magnetic ring.

5. The aforementioned bearing cap is The cylindrical part, The cylindrical portion includes a bottom portion that closes one end of the cylindrical portion, The stator is fixed to the inner diameter surface of the cylindrical portion, The bearing device according to claim 1, wherein the magnetic ring and the stator are opposite each other in a direction intersecting the rotational axis of the bearing device.

6. The stator is, A ring-shaped magnetic yoke fixed to the inner diameter surface of the cylindrical portion, It includes a ring-shaped coil surrounded by the magnetic yoke, The bearing device according to claim 5, wherein the generator formed by the stator and the magnetic ring is a claw-pole type generator.

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