Bearing device

Abstract

To provide a bearing device capable of normally functioning while suppressing the dimension of the bearing device.SOLUTION: A bearing device 1 includes a bearing 2 including an outer ring 3, an inner ring 4 and a rolling element 8, a magnetic ring 7 fixed to the inner ring 4, a stator 5 arranged so as to face the magnetic ring 7 and a radial direction of the bearing 2 and fixed to the outer ring 3, and a circuit board 13. The magnetic ring 7 and the stator 5 constitute a generator G that generates AC power. The circuit board 13 includes at least one sensor that detects a state of the bearing 2, a wireless communication circuit 18, and a power supply circuit 17 that converts AC power generated by the generator G into DC power. The magnetic ring 7, the stator 5, and the circuit board 13 are disposed in an annular space formed by the end portion of the outer ring 3 and the end portion of the inner ring 4 so as not to overlap each other in the axial direction of the bearing 2.SELECTED DRAWING: Figure 2

Description

Technical Field

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

[0002] Bearing devices that combine a bearing and a generator and are used as a power source for sensors, wireless communication, and the like are known.

[0003] Japanese Unexamined Patent Application Publication No. 2017-72170 (Patent Document 1) discloses a bearing device with a wireless sensor that wirelessly transmits information from a sensor. The bearing device disclosed in Patent Document 1 has a structure in which a multi-pole ring magnet is fixed to one end of a cage that holds rolling elements, and a coil is disposed on the seal side facing the multi-pole ring magnet. In the bearing device disclosed in Patent Document 1, electric power is generated by relative rotation between the multi-pole ring magnet disposed in the axial direction and the coil. Prior Art Literature Patent Literature

[0004] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2017-72170 Summary of the Invention Problems to be Solved by the Invention

[0005] Here, the cage experiences large axial play of the bearing during use. For this reason, in the bearing device of Patent Document 1, the gap between the multi-pole ring magnet and the coil in the axial direction tends to fluctuate due to play of the cage accompanying use. It is assumed that when the gap becomes large, the amount of generated power decreases in the bearing device of Patent Document 1, which affects the driving of electronic components such as sensors. Conversely, in the bearing device of Patent Document 1, when the gap becomes small, it is assumed that the multi-pole ring magnet may come into contact with electronic components such as sensors.

[0006] This disclosure was made to solve the above-mentioned problems, and its purpose is to provide a bearing device that can function normally while keeping the dimensions of the bearing device to a minimum. [Means for solving the problem]

[0007] The bearing device of this disclosure comprises a bearing including an outer ring, an inner ring, and rolling elements; a magnetic ring fixed to either the outer ring or the inner ring; a stator positioned radially opposite the magnetic ring and the bearing and fixed to the other of the outer ring or the inner ring; and a circuit board. The magnetic ring and the stator constitute a generator that generates alternating current power. The circuit board includes at least one sensor for detecting the state of the bearing; a wireless communication circuit for wirelessly transmitting the output of at least one sensor to the outside; and a power supply circuit for converting the alternating current power generated by the generator into direct current power usable by at least one sensor and the wireless communication circuit. The magnetic ring, stator, and circuit board are arranged within the annular space formed by the ends of the outer ring and the inner ring such that they do not overlap each other in the axial direction of the bearing. [Effects of the Invention]

[0008] According to the bearing device of this disclosure, the magnetic ring, stator, and circuit board are arranged within the annular space so as not to overlap each other in the axial direction of the bearing. This allows the dimensions of the bearing to be reduced because each component can be arranged within the annular space. Furthermore, in the bearing device of this disclosure, for example, the magnetic ring is fixed to the inner ring and the stator is fixed to the outer ring at an opposing position. The inner and outer rings have minimal axial movement of the bearing, and the magnetic ring and stator constitute a generator, allowing the bearing device to function normally while keeping its dimensions down. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of the entire bearing device according to Embodiment 1. [Figure 2] This is a cross-sectional view in a plane that includes the axis of rotation of the bearing. [Figure 3]This is a diagram to explain the retainer. [Figure 4] This is a view of the bearing device from the sensor unit side. [Figure 5] This is a disassembled perspective view of the sensor unit. [Figure 6] This is a perspective view of the sensor unit after assembly. [Figure 7] This is a cross-sectional view showing the sensor unit and magnetic ring extracted in Embodiment 2. [Figure 8] This is an exploded perspective view of the sensor unit of Embodiment 2. [Figure 9] This is a perspective view of the sensor unit of Embodiment 2 after assembly. [Figure 10] This is a cross-sectional view showing the sensor unit and magnetic ring extracted in Embodiment 3. [Figure 11] This is an exploded perspective view of the sensor unit according to Embodiment 3. [Figure 12] This is a perspective view of the sensor unit of Embodiment 3 after assembly. [Figure 13] This is a cross-sectional view showing the sensor unit and magnetic ring extracted in Embodiment 4. [Figure 14] This is an exploded perspective view of the sensor unit of Embodiment 4. [Figure 15] This is a perspective view of the sensor unit of Embodiment 4 after assembly. [Modes for carrying out the invention]

[0010] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the embodiments described below, when numbers, quantities, etc. are mentioned, the scope of this disclosure is not necessarily limited to those numbers, quantities, etc., unless otherwise specified. The same reference numerals will be used for the same parts and equivalent parts, and redundant descriptions will not be repeated. It is intended from the outset that the configurations in the embodiments will be used in appropriate combinations.

[0011] [Embodiment 1] FIG. 1 is a perspective view of an entire bearing device 1 according to Embodiment 1. The bearing device 1 includes a bearing 2, a sensor unit 6, and a magnetic ring 7. The bearing 2 includes an outer ring 3 and an inner ring 4. In the bearing 2, for example, the outer ring 3 serves as a stationary ring and the inner ring 4 serves as a rotating ring. Although the bearing 2 is described using a deep groove ball bearing as an example, the type of the bearing 2 is not limited to a deep groove ball bearing.

[0012] Here, the bearing 2 is a standard bearing whose main dimensions (inner diameter, outer diameter, width, etc.) are specified in a specific standard. A standard bearing is, for example, a bearing having dimensions specified in ISO standards or JIS standards. The bearing 2 is a radial bearing, and the main dimensions of the bearing 2 are those defined in ISO 15 or JIS B 1512-1. Hereinafter, the bearing 2 is also referred to as the standard bearing 2.

[0013] The sensor unit 6 includes a stator 5 and a cover 14. Details of the structure of the stator 5 will be described later. The cover 14 is a non-metallic resin member that protects the interior of the sensor unit 6. The magnetic ring 7 is a magnetic member that is alternately magnetized with N poles and S poles in the circumferential direction. The stator 5 is fixed to the outer ring 3, and the magnetic ring 7 is fixed to the inner ring 4. A generator G is configured by the stator 5 and the magnetic ring 7. Although the generator G is a claw-pole generator, it may be a generator having another structure. The dashed-dotted line in FIG. 1 indicates the rotation axis O of the bearing 2.

[0014] FIG. 2 is a cross-sectional view taken along a plane including the rotation axis O of the bearing 2. The bearing 2 includes an outer ring 3, an inner ring 4, rolling elements 8, a cage 9, and a seal 10. For the bearing 2, a size of a model number of a standard bearing in which a distance W between an end face 11 of the bearing 2 and the rolling element 8 can accommodate the sensor unit 6 and the magnetic ring 7 may be selected. The end face 11 is also an end face of the outer ring 3.

[0015] A stepped first notch 3a is formed on the inner circumferential surface of one end of the outer ring 3, serving as a recess at the end of the outer ring 3. A stepped second notch 4a is formed on the outer circumferential surface of one end of the inner ring 4, facing the first notch 3a, serving as a recess at the end of the inner ring 4. In the axial direction of the bearing 2, an annular space is formed from the outer ring 3 to the inner ring 4 by the first notch 3a and the second notch 4a, forming an annular recess 50 that is cut out toward the rolling elements 8.

[0016] The sensor unit 6 includes a retaining member 12, a circuit board 13, a stator 5, and a cover 14. The retaining member 12 is a magnetic material having a partition wall 12a separating the retaining member 12 into a first region 12b and a second region 12c in the radial direction (also referred to as the radial direction) of the bearing 2. The circuit board 13 is fixed to the inner bottom surface 12d of the first region 12b, and the stator 5 is arranged in the second region 12c. The cover 14 protects the circuit board 13 fixed to the inner bottom surface 12d. The circuit board 13 may be sealed using a resin encapsulant instead of the cover 14.

[0017] The outer diameter surface of the retaining member 12 on the first region 12b side is fitted and fixed into the first notch 3a formed in the outer ring 3. The retaining member 12 is press-fitted or bonded so as not to protrude from the end face 11 of the outer ring 3. The retaining member 12 may be fixed by a combination of press-fitting and bonding, or by other methods. When the retaining member 12 is fixed into the first notch 3a, a certain gap is ensured between the rolling element 8 and the retaining member 12. This prevents the rolling element 8 and the retaining member 12 from coming into contact even if axial displacement occurs due to the gap.

[0018] The stator 5 includes two magnetic members 21 and 22, a bobbin 23, and a coil 24. The portion of the holding member 12 that includes the second region 12c is used as the magnetic member 21 of the stator 5.

[0019] The magnetic ring 7 includes a core metal 7a and a multipole magnet 7b. The multipole magnet 7b is made, for example, by vulcanizing a magnetic material, which is a mixture of magnetic powder and rubber, onto the core metal 7a, and then alternately magnetizing the north and south poles in the circumferential direction of the bearing 2. The core metal 7a of the magnetic ring 7 has a flange portion 7c to increase its rigidity. The magnetic ring 7 is fixed to the outer diameter surface 4b of the inner ring 4 by press-fitting or the like. The flange portion 7c fits into a second notch portion 4a formed in the inner ring 4. The magnetic ring 7 is positioned so as not to protrude from the end face 20 of the inner ring 4.

[0020] Inside the annular recess 50, the magnetic ring 7, stator 5, and circuit board 13 are arranged so that they do not overlap each other in the axial direction of the bearing 2. This allows each component to be placed inside the annular recess 50, thus reducing the dimensions of the bearing 2. Furthermore, in the bearing device 1, for example, the magnetic ring 7 is fixed to the inner ring 4, and the stator 5 is fixed to the outer ring 3 at an opposing position. Because the axial fluctuation of the bearing 2 is smaller in the inner ring 4 and outer ring 3 compared to the cage 9, a stable power generation amount can be ensured by the generator G, and the bearing device can function normally while keeping its dimensions down.

[0021] Figure 3 is a diagram illustrating the retainer 9. The retainer 9 has recesses 93 formed at a predetermined pitch along the circumferential direction of the axial end face 91 of the annular retainer body. A pair of claw portions 94, 94 are formed to protrude from the circumferentially opposing open ends of the recesses 93. The recesses 93 and the pair of claw portions 94, 94 form a pocket 95 in which the rolling element 8 shown in Figure 2 is housed. Thus, the shape of the retainer 9 is such that one end face 91 is open and the other end face 92 is connected. The retainer 9 is made of resin, and the sensor unit 6 and magnetic ring 7 are arranged on the open side so as not to protrude from the end face 11 and the end face 20.

[0022] Figure 4 is a view of the bearing device 1 from the sensor unit 6 side. In Figure 4, part of the cover 14 is omitted to show the inside of the sensor unit 6. One or more sensors for monitoring the state of the bearing 2 are mounted on the circuit board 13. For example, an acceleration sensor 15 and a temperature sensor 16 are mounted on the circuit board 13. The temperature sensor 16 may be inserted through a hole (not shown) provided in the inner bottom surface 12d of the retaining member 12 and mounted on the back surface of the circuit board 13 so as to be close to (or in contact with) the end face of the first notch 3a of the outer ring 3. This allows the temperature sensor 16 to be close to the outer ring 3 and accurately measure the temperature of the bearing 2.

[0023] The circuit board 13 also has a power supply circuit 17 and a wireless communication circuit 18 mounted on it. The power supply circuit 17 rectifies the AC power generated by the generator G and converts it into DC power. The DC power converted by the power supply circuit 17 is used by the acceleration sensor 15, the temperature sensor 16, and the wireless communication circuit 18. Terminals 25 are located on the circuit board 13.

[0024] The wireless communication circuit 18 includes an antenna section 18a. The wireless communication circuit 18 wirelessly transmits the outputs of the acceleration sensor 15 and temperature sensor 16, which monitor the state of the bearing 2, to the outside using the antenna section 18a. The circuit board 13 is fixed to the retaining member 12 by a plurality of screws 19. The circuit board 13 may also be fixed to the retaining member 12 by adhesive. The circuit board 13 on which the wireless communication circuit 18 is mounted is positioned opposite the resin cover 14. As a result, the wireless communication circuit 18 is not sealed with a conductive material such as metal. Therefore, wireless communication is possible using the antenna section 18a within the wireless communication circuit 18.

[0025] Figure 5 is an exploded perspective view of the sensor unit 6. Figure 6 is an assembled perspective view of the sensor unit 6. The sensor unit 6 includes a retaining member 12, a circuit board 13, and a stator 5. The circuit board 13 is fixed to the inner bottom surface 12d of the first region 12b of the retaining member 12. The stator 5 is located in the second region 12c of the retaining member 12. The stator 5 includes two magnetic members 21 and 22, a bobbin 23, and a coil 24. A portion of the retaining member 12, including the partition wall 12a of the second region 12c, is used as the magnetic member 21 of the stator 5.

[0026] The cross-sections of the magnetic members 21 and 22 are U-shaped. Multiple claw portions 21a are formed on the inner circumference of the magnetic member 21. Multiple claw portions 22a are formed on the inner circumference of the magnetic member 22. A coil 24, in which magnet wire is wound multiple times, is placed in a groove provided in the circumferential direction of the bobbin 23. The bobbin 23 may be omitted.

[0027] The assembly method for the stator 5 is described below. First, with the bobbin 23 on which the coil 24 is wound inserted into the magnetic member 22, the multiple claw portions 21a of the magnetic member 21 and the multiple claw portions 22a of the magnetic member 22 are assembled so that they are arranged alternately with gaps in the circumferential direction. Next, the outer surface 22b of the magnetic member 22 is fixed so that it fits into the inner surface of the partition wall 12a of the magnetic member 21.

[0028] The multiple claw portions 21a of the magnetic member 21 and the multiple claw portions 22a of the magnetic member 22 are arranged opposite each other, with a gap secured between them and the multipole magnet 7b of the magnetic ring 7 shown in Figure 2. The multiple claw portions 21a of the magnetic member 21 and the multiple claw portions 22a of the magnetic member 22 in the stator 5 and the magnetic ring 7 constitute a claw-pole type generator G. The total number of claw portions 21a and 22a is equal to the number of poles of the multipole magnet 7b (the total number of N poles and S poles).

[0029] The magnetic flux emanating from the north pole of the multipole magnet 7b enters the magnetic material member 21 (or magnetic material member 22) through, for example, the multiple claw portions 21a (or multiple claw portions 22a) which are the magnetic poles, circulates around the coil 24, passes through adjacent multiple claw portions 22a (or multiple claw portions 21a), and returns to the south pole of the multipole magnet 7b. When the positions of the north and south poles of the multipole magnet 7b are swapped by the rotation of the inner ring 4, the direction of the magnetic flux is reversed. The alternating magnetic field generated in this way generates alternating current power at both ends of the coil 24.

[0030] The beginning and end ends (not shown) of the coil 24 drawn from the stator 5 are connected to terminals 25 provided on the circuit board 13. The AC power output from the generator G as the inner ring 4 rotates is converted to DC power by the power supply circuit 17.

[0031] The sensor unit 6 of the bearing device 1 is divided into two regions, a first region 12b and a second region 12c, radially around the holding member 12 by a partition wall 12a. The circuit board 13 is located in the first region 12b, and the stator 5 of the claw-pole type generator G is located in the second region 12c. The magnetic ring 7 is located on the inner diameter side facing the stator 5.

[0032] Thus, the bearing device 1 has a structure in which the circuit board 13, stator 5, and magnetic ring 7 are arranged in order so that they do not overlap each other in the axial direction of the bearing 2. Furthermore, the bearing device 1 is shaped so that the sensor unit 6 does not protrude from the end face 11 of the bearing 2, and the magnetic ring 7 does not protrude from the end face 20 of the inner ring 4. As a result, the sensor unit 6 can be manufactured to be thin in the axial direction in the bearing device 1.

[0033] The bearing device 1 has a stator 5 and a magnetic ring 7 arranged in the radial direction, forming a claw-pole type generator G. Therefore, since the stator 5 and magnetic ring 7 are fixed to parts that have little play due to the use of the bearing device 1, a stable amount of power can be ensured by the generator G.

[0034] Here, the retaining member 12 is divided into two regions, a first region 12b and a second region 12c, by a partition wall 12a. The portion of the retaining member 12 including the first region 12b is used to hold the circuit board 13, and the portion of the retaining member 12 including the second region 12c is also used as a magnetic material member 21. As a result, the bearing device 1 can reduce the number of parts and firmly fix the stator 5 to the retaining member 12.

[0035] [Embodiment 2] In Embodiment 2, a sensor unit 6A with a different structure from the sensor unit 6 of Embodiment 1 will be described. Figure 7 is a cross-sectional view showing the sensor unit 6A and magnetic ring 7 in Embodiment 2. Figure 8 is an exploded perspective view of the sensor unit 6A of Embodiment 2. Figure 9 is an assembled perspective view of the sensor unit 6A of Embodiment 2. In the following, the same configuration as the sensor unit 6 of Embodiment 1 will not be described.

[0036] The sensor unit 6A includes a retaining member 12A, a circuit board 13, a stator 5A, and a cover 14. The retaining member 12A has the partition wall 12a of Embodiment 1 removed. The retaining member 12A is annular in shape and has a U-shaped cross-section with an outer circumference 12Ab, an inner circumference 12Aa, and a bottom portion 12Ad connecting the outer circumference 12Ab and the inner circumference 12Aa. The stator 5A is fixed to the side surface of the inner circumference 12Aa by press-fitting. The stator 5A may be fixed by adhesive, or by a combination of press-fitting and adhesive. The circuit board 13 is fixed to the bottom portion 12Ad of the retaining member 12A.

[0037] The stator 5A includes a magnetic member 26, a bobbin 23, and a coil 24. The magnetic member 26 includes magnetic member 26-1 and magnetic member 26-2. The cross-sections of magnetic members 26-1 and 26-2 are U-shaped. Multiple claw portions 26a are formed on the inner circumference of magnetic member 26-1. Multiple claw portions 26b are formed on the inner circumference of magnetic member 26-2. The multiple claw portions 26a and multiple claw portions 26b are arranged alternately with gaps in the circumferential direction.

[0038] Multiple recesses 26c and protrusions 26d are formed on the outer periphery of magnetic members 26-1 and 26-2. By fitting the recesses 26c and protrusions 26d together, the alignment of multiple claw portions 26a and multiple claw portions 26b becomes easier.

[0039] The retaining member 12A, magnetic member 26-1, and magnetic member 26-2 have a U-shaped cross-section and a simple shape, which facilitates press forming and reduces manufacturing costs.

[0040] [Embodiment 3] In Embodiment 3, a sensor unit 6B with a different structure from the sensor unit 6 of Embodiment 1 will be described. Figure 10 is a cross-sectional view showing the sensor unit 6B and magnetic ring 7 in Embodiment 3. Figure 11 is an exploded perspective view of the sensor unit 6B of Embodiment 3. Figure 12 is an assembled perspective view of the sensor unit 6B of Embodiment 3. In the following, the same configuration as the sensor unit 6 of Embodiment 1 will not be described.

[0041] The sensor unit 6B includes a retaining member 12B, a circuit board 13, a stator 5B, and a cover 14. The retaining member 12B of the sensor unit 6B has the function of fixing the circuit board 13 and the function of being a magnetic material member 27 of the stator 5B. The retaining member 12B (magnetic material member 27) is annular in shape and has a U-shaped cross-section with an outer circumference 27a, an inner circumference 27b, and a bottom portion 27c connecting the outer circumference 27a and the inner circumference 27b. The inner circumference 27b is formed by a plurality of claw portions 27d. A plurality of recesses 27e are formed in the bottom portion 27c, spaced apart in the circumferential direction of the bearing 2.

[0042] The stator 5B includes a magnetic member 28. The magnetic member 28 has an annular shape and a U-shaped cross-section having an outer circumference 28a, an inner circumference 28b, and a bottom portion 28c connecting the outer circumference 28a and the inner circumference 28b. The inner circumference 28b is formed by a plurality of claw portions 28d facing a plurality of claw portions 27d of the magnetic member 27. At the axial end of the bearing 2 on the outer circumference 28a, a plurality of protrusions 28e are formed, spaced apart in the circumferential direction of the bearing 2.

[0043] The assembly method for the stator 5B is described below. With the bobbin 23 on which the coil 24 is wound inserted into the magnetic member 28, the protrusions 28e of the magnetic member 28 and the recesses 27e of the magnetic member 27 are fitted together. As the multiple recesses 27e and multiple protrusions 28e are fitted together, the multiple claws 27d of the magnetic member 27 and the multiple claws 28d of the magnetic member 28 are arranged alternately with gaps in the circumferential direction. The multiple recesses 27e and multiple protrusions 28e facilitate the alignment of the multiple claws 27d and the multiple claws 28d. The end faces of the magnetic member 28, excluding the protrusions 28e, abut against the bottom 27c of the magnetic member 27.

[0044] The recess 27e of the magnetic member 27 and the protrusion 28e of the magnetic member 28 are fixed by press-fitting. However, the recess 27e and the protrusion 28e may also be fixed by adhesive bonding or laser welding. Alternatively, the recess 27e and the protrusion 28e may be fixed by a combination of press-fitting, adhesive bonding, and welding. By fitting the recess 27e and the protrusion 28e together, the coaxial alignment of the two magnetic members 27 and 28 can be easily performed without using a jig, and the positioning of the multiple claw portions 27d and 28d can be easily performed. It is preferable that three or more recesses 27e and three or more protrusions 28e are formed.

[0045] Since the retaining member 12B also functions as the magnetic member 27, the number of parts can be reduced. Because the magnetic members 27 and 28 have a U-shaped cross-section and a simple shape, press forming is easy, and manufacturing costs can be reduced.

[0046] Note that the recessed portion 27e and the convex portion 28e may be omitted. In this case, with the coaxial alignment of the magnetic members 27 and 28 and the multiple claw portions 27d and 28d performed using a jig (not shown), the contact surfaces between the bottom portion 27c of the magnetic member 27 and the end of the outer peripheral portion 28a of the magnetic member 28 may be fixed by laser welding or the like.

[0047] [Embodiment 4] In Embodiment 4, a sensor unit 6C with a different structure from the sensor unit 6 of Embodiment 1 will be described. Figure 13 is a cross-sectional view showing the sensor unit 6C and magnetic ring 7 in Embodiment 4. Figure 14 is an exploded perspective view of the sensor unit 6C of Embodiment 4. Figure 15 is an assembled perspective view of the sensor unit 6C of Embodiment 4. In the following, the same configuration as the sensor unit 6 of Embodiment 1 will not be described.

[0048] The sensor unit 6C includes a circuit board 13 and a stator 5C. The sensor unit 6C's holding member for the stator 5C is formed of a magnetic member 29 that extends radially from the bearing 2. The magnetic member 29 includes a magnetic member 29-1 and a magnetic member 29-2. The magnetic member 29-1 has an annular shape and a U-shaped cross-section with an outer circumference 29-1b, an inner circumference 29-1a, and a bottom portion 29-1d connecting the outer circumference 29-1b and the inner circumference 29-1a. The inner circumference 29-1a is formed by a plurality of claw portions 29a.

[0049] The magnetic member 29-2 has an annular shape and a U-shaped cross-section, having an outer circumference 29-2b, an inner circumference 29-2a, and a bottom portion 29-2d connecting the outer circumference 29-2b and the inner circumference 29-2a. The inner circumference 29-2a is formed by a plurality of claw portions 29b. The plurality of claw portions 29a and the plurality of claw portions 29b are arranged alternately with gaps in the circumferential direction.

[0050] Multiple protrusions 29c and recesses 29d are formed on the outer periphery 29-1b and 29-2b of the magnetic members 29-1 and 29-2. By fitting the protrusions 29c and recesses 29d together, the alignment of multiple claw portions 29a and multiple claw portions 29b becomes easier. The magnetic member 29 is positioned at one end of the bearing 2.

[0051] The bobbin 23 on which the coil 24 is wound is positioned on the inner circumference side where multiple claw portions 29a and multiple claw portions 29b are located. The circuit board 13 is positioned on the outer circumference side opposite to the radial direction of the coil 24 and the bearing 2. The circuit board 13 is fixed, for example, to the bottom portion 29-1d of the magnetic member 29-1 with screws (not shown). A hole 29e is formed on the side surface (bottom portion 29-2d) of the magnetic member 29-2 opposite to the position where the antenna portion 18a of the wireless communication circuit 18 is located.

[0052] The hole 29e is closed by a non-conductive resin member 30. This allows the sensor unit 6C to transmit wireless communication radio waves to the outside through the hole 29e, and also protects the coil 24, circuit board 13, etc. located inside by preventing foreign matter from entering the internal space of the magnetic member 29 from the outside. Alternatively, a resin sealant may be injected through the hole 29e to cover the circuit board 13, etc. with the resin material. In this case, multiple holes can be provided in the circumferential direction of the bottom portion 29-2d of the magnetic member 29-2, and the resin sealant can be injected through each hole to prevent air bubbles from remaining in the internal space of the magnetic member 29.

[0053] In the sensor unit 6C, the circuit board 13 is mounted in an internal space formed by magnetic material members 29-1 and 29-2. This allows the circuit board 13 to be protected by the magnetic material member 29. Since the holding member of the sensor unit 6C is formed from magnetic material member 29-1 and magnetic material member 29-2 also serves as a lid, the number of parts can be reduced.

[0054] (modified version) In the embodiment described above, the example was explained in which the outer ring 3 was a fixed ring and the inner ring 4 was a rotating ring, but the outer ring 3 may be a rotating ring and the inner ring 4 a fixed ring. In this case, the structure can be such that the magnetic ring 7 is fixed to the outer ring 3 and the sensor units 6, 6A, 6B, and 6C are fixed to the inner ring 4.

[0055] (summary) The bearing device 1 of this disclosure comprises a bearing 2 including an outer ring 3, an inner ring 4, and rolling elements 8; a magnetic ring 7 fixed to either the outer ring 3 or the inner ring 4; a stator 5 arranged radially opposite the magnetic ring 7 and the bearing 2 and fixed to the other of the outer ring 3 or the inner ring 4; and a circuit board 13. The magnetic ring 7 and the stator 5 constitute a generator G that generates alternating current power. The circuit board 13 includes at least one sensor (e.g., an acceleration sensor 15, a temperature sensor 16) for detecting the state of the bearing 2; a wireless communication circuit 18 for wirelessly transmitting the output of at least one sensor to the outside; and a power supply circuit 17 for converting the alternating current power generated by the generator G into DC power usable by at least one sensor and the wireless communication circuit 18. The magnetic ring 7, the stator 5, and the circuit board 13 are arranged in an annular space formed by the ends of the outer ring 3 and the inner ring 4 such that they do not overlap each other in the axial direction of the bearing 2.

[0056] With this configuration, the magnetic ring 7, stator 5, and circuit board 13 are arranged within the annular space so that they do not overlap each other in the axial direction of the bearing 2. This allows each component to be placed within the annular space, thus reducing the dimensions of the bearing 2. Furthermore, in the bearing device 1, for example, the magnetic ring 7 is fixed to the inner ring 4, and the stator 5 is fixed to the outer ring 3 at an opposing position. Because the axial fluctuation of the bearing 2 is small, the inner ring 4 and outer ring 3 can ensure a stable power output from the generator G and function normally while keeping the dimensions of the bearing device small.

[0057] Preferably, the annular space is formed by a first notch 3a formed on the inner circumferential surface of one end of the outer ring 3, and a second notch 4a formed on the outer circumferential surface of one end of the inner ring 4 so as to be opposite to the first notch 3a.

[0058] By having this configuration, the components can be arranged in the annular space formed by the first notch 3a and the second notch 4a, thereby reducing the dimensions of the bearing 2.

[0059] Preferably, a retaining member 12 for holding the circuit board 13 and stator 5 is fixed to either the first notch 3a or the second notch 4a, and a magnetic ring 7 is fixed to the other of the first notch 3a or the second notch 4a.

[0060] With this configuration, for example, a retaining member 12 that holds the circuit board 13 and stator 5 is fixed to the first notch 3a, and a magnetic ring 7 is fixed to the second notch 4a. As a result, the stator 5 and magnetic ring 7 are fixed to components that have little play due to the use of the bearing device 1, so that a stable amount of power can be generated by the generator G.

[0061] Preferably, the retaining member 12 is a magnetic material having a partition wall 12a separating the retaining member 12 into a first region 12b and a second region 12c in the radial direction of the bearing 2. The portion of the retaining member 12 that includes either the first region 12b or the second region 12c is used as the stator 5.

[0062] With this configuration, for example, the retaining member 12 is divided into two regions, a first region 12b and a second region 12c, by a partition wall 12a. The portion of the retaining member 12 including the first region 12b is used to hold the circuit board 13, and the portion of the retaining member 12 including the second region 12c is also used as a magnetic material member 21. As a result, the bearing device 1 can reduce the number of parts and firmly fix the stator 5 to the retaining member 12.

[0063] Preferably, the retaining member 12A has an annular shape and a U-shaped cross-section having an outer circumference 12Ab, an inner circumference 12Aa, and a bottom portion 12Ad connecting the outer circumference 12Ab and the inner circumference 12Aa. The stator 5 is fixed to either the outer circumference 12Ab or the inner circumference 12Aa, and the circuit board 13 is fixed to the bottom portion 12Ad.

[0064] By having such a configuration, the retaining member 12A has a U-shaped cross-section and a simple shape, which makes press forming easier and reduces manufacturing costs.

[0065] Preferably, the stator 5B includes a coil 24 and a magnetic material member 27 having a plurality of claw portions 27d and a magnetic material member 28 having a plurality of claw portions 28d. The coil 24 is housed in an internal space formed by combining the magnetic material member 27 and the magnetic material member 28. The retaining member 12B is the magnetic material member 27. The shape of the magnetic material member 27 is annular, and its cross-section is U-shaped, having an outer circumference 27a, an inner circumference 27b, and a bottom portion 27c connecting the outer circumference 27a and the inner circumference 27b. The inner circumference 27b is formed by a plurality of claw portions 27d. A plurality of recesses 27e are formed in the bottom portion 27c, spaced apart in the circumferential direction of the bearing 2. The shape of the magnetic material member 28 is annular, and its cross-section is U-shaped, having an outer circumference 28a, an inner circumference 28b, and a bottom portion 28c connecting the outer circumference 28a and the inner circumference 28b. The inner circumference 28b is formed by a plurality of claw portions 27d and a plurality of opposing claw portions 28d. At the axial end of the bearing 2 on the outer circumference 28a, a plurality of protrusions 28e are formed, spaced apart in the circumferential direction of the bearing 2. The plurality of recesses 27e and the plurality of protrusions 28e fit together so that the plurality of claw portions 27d and the plurality of claw portions 28d are arranged alternately with gaps between them in the circumferential direction of the bearing 2.

[0066] By having this configuration, the retaining member 12B also functions as the magnetic member 27, thus reducing the number of parts. The magnetic members 27 and 28 have a U-shaped cross-section and a simple shape, making press forming easy and reducing manufacturing costs. By fitting the recess 27e and the protrusion 28e together, the coaxial alignment of the two magnetic members 27 and 28 can be easily performed without using a jig, and the positioning of the multiple claw portions 27d and 28d can be easily performed.

[0067] Preferably, the stator 5C includes a coil 24 and a magnetic member 29-1 having a plurality of claw portions 29a and a magnetic member 29-2 having a plurality of claw portions 29b. The coil 24 is housed in an internal space formed by combining the magnetic member 29-1 and the magnetic member 29-2. The holding members are the magnetic member 29-1 and the magnetic member 29-2. The shape of the magnetic member 29-1 is annular, and its cross-section is U-shaped, having an outer circumference 29-1b, an inner circumference 29-1a, and a bottom portion 29-1d connecting the outer circumference 29-1b and the inner circumference 29-1a. The outer circumference 29-1b or the inner circumference 29-1a is formed by a plurality of claw portions 29a. The magnetic member 29-2 has an annular shape and a U-shaped cross-section having an outer circumference 29-2b, an inner circumference 29-2a, and a bottom portion 29-2d connecting the outer circumference 29-2b and the inner circumference 29-2a. The outer circumference 29-2b or the inner circumference 29-2a is formed by a plurality of claw portions 29b. The magnetic member 29 is positioned at one end of the bearing 2. The plurality of claw portions 29a and claw portions 29b are arranged alternately with gaps between them in the circumferential direction of the bearing 2. The coil 24 is positioned on the side where the plurality of claw portions 29a and claw portions 29b are located. The circuit board 13 is positioned on the radially opposite side of the coil 24 and the bearing. The wireless communication circuit 18 includes an antenna portion 18a. A hole portion 29e is formed on the side of the magnetic member 29-2 opposite the position where the antenna portion 18a is positioned.

[0068] By adopting this configuration, the holding member itself is formed from the magnetic material member 29-1, and the magnetic material member 29-2 also serves as a lid, thus reducing the number of parts. Furthermore, radio waves for wireless communication can be transmitted to the outside from the hole 29e, and foreign matter can be prevented from entering the internal space of the magnetic material member 29 from the outside, thereby protecting the coil 24, circuit board 13, etc. located inside.

[0069] The bearing device 1 of this disclosure comprises a standard bearing 2 whose main dimensions, including an outer ring 3, an inner ring 4, and rolling elements 8, are specified in a particular standard. The bearing device 1 comprises a magnetic ring 7 fixed to either the outer ring 3 or the inner ring 4, a stator 5 positioned radially opposite the magnetic ring 7 and the standard bearing 2 and fixed to the other of the outer ring 3 or the inner ring 4, and a circuit board 13. The magnetic ring 7 and the stator 5 constitute a generator G that generates alternating current power. The circuit board 13 includes at least one sensor (e.g., an acceleration sensor 15, a temperature sensor 16) for detecting the state of the standard bearing 2, a wireless communication circuit 18 for wirelessly transmitting the output of at least one sensor to the outside, and a power supply circuit 17 for converting the alternating current power generated by the generator G into DC power usable by at least one sensor and the wireless communication circuit 18. The magnetic ring 7, the stator 5, and the circuit board 13 are arranged in an annular space formed by the ends of the outer ring 3 and the inner ring 4.

[0070] By having this configuration, each component can be arranged within an annular space, thus reducing the dimensions of the standard bearing 2. Furthermore, in the bearing device 1, for example, the magnetic ring 7 is fixed to the inner ring 4, and the stator 5 is fixed to the outer ring 3 at an opposing position. Because the axial fluctuation of the bearing 2 is small, the inner ring 4 and outer ring 3 can ensure a stable power output by the generator G, and the bearing device can function normally while keeping its dimensions down.

[0071] Preferably, the magnetic ring 7, stator 5, and circuit board 13 are arranged within the annular space so as not to overlap each other in the axial direction of the standard bearing 2.

[0072] By having this configuration, each component can be arranged within the annular space, which allows the dimensions of the standard bearing 2 to be reduced.

[0073] Preferably, the circuit board 13 has an arc shape. At least one sensor, a wireless communication circuit 18, and a power supply circuit 17 are arranged on the circumference of the circuit board 13 so as not to overlap each other in the axial direction.

[0074] By adopting this configuration, multiple electronic components can be arranged on the circumference of the circuit board 13 without increasing the axial thickness of the standard bearing 2, thereby reducing the dimensions of the standard bearing 2.

[0075] Preferably, the specific standard is ISO or JIS. By having this configuration, it can be applied to standard bearings with dimensions specified in ISO or JIS standards.

[0076] Preferably, the standard bearing 2 is a radial bearing. The main dimensions of the radial bearing are those specified in ISO 15 or JIS B1512-1.

[0077] By having this configuration, it can be applied to standard bearings with dimensions specified in ISO 15 or JIS B1512-1.

[0078] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure 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]

[0079] 1 Bearing device, 2 Bearing, standard bearing, 3 Outer ring, 3a First notch, 4 Inner ring, 4a Second notch, 5, 5A, 5B, 5C Stator, 6, 6A, 6B, 6C Sensor unit, 7 Magnetic ring, 7a Core metal, 7b Multipole magnet, 8 Rolling element, 9 Cage, 10 Seal, 12, 12A, 12B Retaining member, 12Aa, 27b, 28b, 29-1a Inner circumference, 12Ab, 27a, 28a, 29-1b Outer circumference, 12Ad, 27c, 28c, 29-1d Bottom, 12a Partition wall, 12b First region, 12c Second region, 13 Circuit board, 14 Cover, 15 Acceleration sensor, 16 Temperature sensor, 17 Power supply circuit, 18 Wireless communication circuit, 18a Antenna section, 21, 22, 26, 27, 28, 29 Magnetic material members, 21a, 22a, 26a, 26b, 27d, 28d, 29a, 29b Multiple claw sections, 23 Bobbin, 24 Coil, 26c, 27e, 29d Recesses, 26d, 28e, 29c Protrusions, 29e Hole, 30 Resin member, 50 Annular recess, G Generator, O Rotating shaft.

Claims

1. A bearing including an outer ring, an inner ring, and rolling elements, A magnetic ring fixed to either the outer ring or the inner ring, A stator is arranged to face the magnetic ring and the bearing in the radial direction and is fixed to either the outer ring or the inner ring, A circuit board and, The magnetic ring and the stator constitute a generator that generates alternating current power. The circuit board includes at least one sensor for detecting the state of the bearing, and a wireless communication circuit for wirelessly transmitting the output of the at least one sensor to the outside. The bearing further comprises a non-conductive resin member positioned in the axial direction opposite to the wireless communication circuit, A bearing device in which the magnetic ring, the stator, and the circuit board are arranged in an annular space formed by the end of the outer ring and the end of the inner ring such that they do not overlap each other in the axial direction of the bearing.

2. The bearing device according to claim 1, wherein the annular space is formed by a first notch formed on the inner circumferential surface of one end of the outer ring and a second notch formed on the outer circumferential surface of one end of the inner ring so as to be opposite to the first notch.

3. The bearing device according to claim 2, wherein a retaining member for holding the circuit board and the stator is fixed to one of the first notch or the second notch, and the magnetic ring is fixed to the other of the first notch or the second notch.

4. The retaining member is a magnetic material having a partition wall separating the retaining member into a first region and a second region in the radial direction of the bearing. The bearing device according to claim 3, wherein the portion of the retaining member including either the first region or the second region is used as the stator.

5. The shape of the retaining member is annular, and its cross-section is U-shaped, having an outer circumference, an inner circumference, and a bottom portion connecting the outer circumference and the inner circumference. The stator is fixed to either the outer circumference or the inner circumference, The bearing device according to claim 3, wherein the circuit board is fixed to the bottom.

6. The stator includes a coil and a first magnetic material member having a plurality of first claw portions and a second magnetic material member having a plurality of second claw portions. The coil is housed in an internal space formed by combining the first magnetic material member and the second magnetic material member. The holding member is the first magnetic material member, The shape of the first magnetic material member is annular, and its cross-section is U-shaped, having a first outer periphery, a first inner periphery, and a first bottom portion connecting the first outer periphery and the first inner periphery. The first inner circumference or the first outer circumference is formed by the first plurality of claw portions, The first bottom portion has a plurality of recesses that are spaced apart in the circumferential direction of the bearing. The shape of the second magnetic material member is annular, and its cross-section is U-shaped, having a second outer periphery, a second inner periphery, and a second bottom portion connecting the second outer periphery and the second inner periphery. The second inner circumferential portion or the second outer circumferential portion is formed by the second plurality of claw portions facing the first plurality of claw portions, Multiple protrusions are formed at the axial end of the bearing on the other of the second outer circumference or the second inner circumference, spaced apart in the circumferential direction of the bearing. The bearing device according to claim 3, wherein the plurality of recesses and the plurality of protrusions fit together so that the first plurality of claws and the second plurality of claws are arranged alternately with gaps between them in the circumferential direction of the bearing.

7. The stator includes a coil and a first magnetic material member having a plurality of first claw portions and a second magnetic material member having a plurality of second claw portions. The coil is housed in an internal space formed by combining the first magnetic material member and the second magnetic material member. The holding member is the first magnetic material member and the second magnetic material member, The shape of the first magnetic material member is annular, and its cross-section is U-shaped, having a first outer periphery, a first inner periphery, and a first bottom portion connecting the first outer periphery and the first inner periphery. The first outer circumference or the first inner circumference is formed by the first plurality of claw portions, The shape of the second magnetic material member is annular, and its cross-section is U-shaped, having a second outer periphery, a second inner periphery, and a second bottom portion connecting the second outer periphery and the second inner periphery. The second outer circumference or the second inner circumference is formed by the second plurality of claw portions, The second magnetic member is positioned at one end of the bearing, The first plurality of claw portions and the second plurality of claw portions are arranged alternately with gaps between them in the circumferential direction of the bearing. The coil is positioned on the side where the first plurality of claw portions and the second plurality of claw portions are located. The circuit board is positioned on the radially opposite side of the coil and the bearing. The wireless communication circuit includes an antenna section, The bearing device according to claim 3, wherein a hole is formed on the side surface of the second magnetic material member opposite to the position where the antenna portion is arranged.

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