Bearing device

Abstract

To suppress the dimensions of a sensor unit to reduce a space required for arranging the sensor unit and a magnetic ring, in a bearing device in which the magnetic ring is attached to a rotary member, the sensor unit provided with a sensor, a wireless communication circuit, a power supply circuit and a stator is attached to a mating member, and the stator and the magnetic ring are opposite to each other in a radial direction.SOLUTION: A stator 7 is provided with a finite length in a circumferential direction in a sensor unit 4. The stator 7, a sensor 11, a wireless communication circuit 12 and a power supply circuit 13 are arranged on the same circumference.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a bearing device including a bearing and a sensor unit. [Background technology]

[0002] Conventionally, there has been known a bearing device in which a sensor and a wireless module for detecting the condition of a rolling bearing are mounted on a circuit board, this circuit board is housed in a sensor unit, the magnetic ring of a claw-pole type generator is connected to the rotating ring of the rolling bearing, the stator of the claw-pole type generator is provided in the sensor unit, and the sensor unit is connected to the stationary ring of the rolling bearing (for example, Patent Document 1).

[0003] The bearing device disclosed in Patent Document 1 converts the rotational motion of the rotating ring relative to the stationary ring into AC power using a stator and a magnetic ring that face each other in the radial direction, and this AC power is converted into DC power by a power supply circuit on a circuit board and supplied to a sensor and a wireless module, making it possible to wirelessly monitor the condition of the rolling bearing. In particular, the sensor and the stator are not aligned in the radial direction but are arranged at different positions in the axial direction, so that the outer diameter of the sensor unit can be reduced. Therefore, even if the outer diameter of the bearing is small, the stator of the sensor unit and the magnetic ring can be arranged to face each other in the radial direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-156079 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the bearing device of Patent Document 1, the sensor and the like of the sensor unit and the stator are located at different positions in the axial direction, which results in a large axial width of the sensor unit. Therefore, when the axial width of the space available for arranging the sensor unit is small, it becomes difficult to adopt a sensor unit such as that of Patent Document 1.

[0006] If the sensor etc. and the stator are arranged in the same axial position, it is possible to reduce the axial width of the sensor unit, but when the outer diameter of the bearing is small, such as in a small bearing, it becomes difficult to ensure a space within the inner and outer diameters of the bearing that allows the sensor etc., the stator, the air gap, and the magnetic ring to be arranged in the same axial position. Similar problems arise even when the sensor unit and the magnetic ring are arranged between a rotating side spacer and a stationary side spacer provided in the bearing device, because the width and diameter of the spacer adjacent to the small bearing are small.

[0007] Therefore, the problem that this invention aims to solve is to reduce the dimensions of the sensor unit and the space required for arranging the sensor unit and magnetic ring in a bearing device in which a magnetic ring is attached to a rotating member, a sensor unit having a sensor, a wireless communication circuit, a power supply circuit, and a stator is attached to a mating member, and the stator and magnetic ring are radially opposed. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention adopts configuration 1, which is a bearing device comprising a rotating member, a bearing for rotatably supporting the rotating member, a mating member arranged coaxially with the rotating member, a sensor unit attached to the mating member, and a generator for converting the rotational motion of the rotating member into AC power, wherein the sensor unit has a storage section for accommodating a sensor, a wireless communication circuit for transmitting the detection result of the sensor, and a power supply circuit for converting the AC power into DC power, and the generator has a magnetic ring that rotates integrally with the rotating member and a stator provided in the sensor unit, the magnetic ring and the stator are disposed in positions radially opposing each other, wherein the stator is provided with a finite length in the circumferential direction, and the stator, the sensor, the wireless communication circuit, and the power supply circuit are disposed on the same circumference.

[0009] As in the above configuration 1, the sensor unit is provided with a stator of a finite length in the circumferential direction, and the stator, sensor, wireless communication circuit, and power supply circuit are arranged on the same circumference, so that the axial width of the sensor unit can be reduced while avoiding an increase in the diameter of the sensor unit, thereby reducing the space required for arranging the sensor unit and the magnetic ring.

[0010] In the above configuration 1, a configuration 2 can be adopted in which the stator has a yoke and a coil arranged at a position radially facing the magnetic ring, the yoke has a first claw pole portion and a second claw pole portion arranged alternately at a circumferential interval, a first side wall portion extending from the first claw pole portion toward the antimagnetic ring side in the radial direction, a second side wall portion extending from the second claw pole portion toward the antimagnetic ring side in the radial direction, and a connecting wall portion extending between the first side wall portion and the second side wall portion with a finite length in the circumferential direction, and the coil is wound around the connecting wall portion so as to have a first coil portion passing between the first side wall portion and the second side wall portion in the circumferential direction and a second coil portion passing through a position on the antimagnetic ring side with respect to the connecting wall portion in the circumferential direction. According to this configuration 2, a claw pole type generator can be provided with a finite length in the circumferential direction.

[0011] In the above configuration 2, a configuration 3 can be adopted in which the yoke is made of a first magnetic material member and a second magnetic material member provided with a finite length in the circumferential direction, the first magnetic material member has an annular side plate portion including the first side wall portion, the first claw pole portion extending from the magnetic ring side of the annular side plate portion to one side in the axial direction, a circumferential plate portion extending from the magnetic ring side of the annular side plate portion to one side in the axial direction and extending a finite length in the circumferential direction on the same circumference as the first claw pole portion, and an annular plate portion extending from the antimagnetic ring side of the annular side plate portion to one side in the axial direction, the second magnetic material member has the second side wall portion, the second claw pole portion extending from the magnetic ring side of the second side wall portion to the other side in the axial direction, and the connecting wall portion extending from the antimagnetic ring side of the second side wall portion to the other side in the axial direction, and the sensor, the wireless communication circuit, and the power supply circuit are accommodated between the annular plate portion and the circumferential plate portion of the first magnetic material member. According to configuration 3, the storage section for accommodating a sensor and the like and the yoke can be provided on the same circumference using only two members, the first magnetic member and the second magnetic member.

[0012] In the above configuration 3, a configuration 4 can be adopted in which the sensor unit has an arc-shaped bobbin axially stacked on the annular side plate portion, the arc-shaped bobbin has a first groove portion that radially supports the first coil portion, a second groove portion that radially supports the second coil portion, and a partition portion that forms a slit that penetrates in the axial direction between the first groove portion and the second groove portion, and the connection wall portion reaches the annular side plate portion through the slit. According to this configuration 4, it is possible to simultaneously maintain the coil in a form that is wound around the connection wall portion by the support of the arc-shaped bobbin and provide a yoke by combining a first magnetic member and a second magnetic member.

[0013] In any one of the above configurations 1 to 4, a configuration 5 can be adopted in which the rotating member is made of a first raceway, the mating member is made of a second raceway, the bearing is a rolling bearing having rolling elements arranged between the rotating member and the mating member, the rotating member and the mating member have stepped ends facing each other in the radial direction, the magnetic ring is fitted into the stepped end of the rotating member so as not to protrude from the rotating member in the axial direction, and the sensor unit is fitted into the stepped end of the mating member so as not to protrude from the mating member in the axial direction. According to this configuration 5, the annular space inside the bearing is expanded by the stepped ends of the rotating member and the mating member, so that the sensor unit and the magnetic ring can be accommodated in the bearing without expanding the outer diameter of the bearing, and thus a compact bearing device can be realized. Effect of the Invention

[0014] As described above, by adopting the above configuration 1, the present invention makes it possible to reduce the dimensions of the sensor unit and the space required for arranging the sensor unit and the magnetic ring in a bearing device in which a magnetic ring is attached to a rotating member, a sensor unit having a sensor, a wireless communication circuit, a power supply circuit, and a stator is attached to a mating member, and the stator and the magnetic ring are radially opposed to each other, thereby making it possible to reduce the dimensions of the sensor unit and the space required for arranging the sensor unit and the magnetic ring. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view showing a bearing device according to a first embodiment of the present invention with a cover removed; [Diagram 2] FIG. 2 is a longitudinal sectional front view of the bearing device in FIG. 1 near a sensor unit; [Diagram 3] FIG. 2 is an exploded perspective view showing the bearing device of FIG. 1 with the sensor unit and the magnetic ring removed. [Figure 4] FIG. 2 is a perspective view showing a state in which covers are attached to the sensor unit of the bearing device of FIG. 1; [Diagram 5] FIG. 2 is an exploded perspective view of the sensor unit of FIG. 1; [Figure 6] A longitudinal sectional front view of the stator of the sensor unit in FIG. [Figure 7] FIG. 2 is a perspective view showing the sensor unit of FIG. 1 in the process of being assembled; [Figure 8] FIG. 2 is a side view of the bearing device of FIG. [Figure 9] FIG. 2 is a longitudinal sectional front view showing the bearing device of FIG. [Figure 10] FIG. 4 is a cross-sectional view showing a bearing device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] A bearing device according to a first embodiment (hereinafter simply referred to as "the bearing device") as one example of the present invention will be described with reference to FIGS. 1 to 9 of the accompanying drawings.

[0017] As shown in FIGS. 1 to 3, this bearing device includes a rotating member 1, a bearing 2, a mating member 3 arranged coaxially with the rotating member 1, a sensor unit 4 attached to the mating member 3, and a generator 5.

[0018] Here, the circumferential direction centered on the central axis of rotation of the rotating member 1 is referred to as the "circumferential direction," the direction along the central axis of rotation is referred to as the "axial direction," and the direction perpendicular to the central axis of rotation is referred to as the "radial direction."

[0019] The rotating member 1 is a member that rotates relatively to the mating member 3 in the circumferential direction.

[0020] The bearing 2 is a mechanism that supports the rotating member 1 so as to be rotatable in the circumferential direction.

[0021] The counter member 3 is a member disposed coaxially with the rotating member 1 .

[0022] The sensor unit 4 is a unit that incorporates an electric circuit that uses a generator 5 as a power source, detects at least one of a physical quantity and a chemical quantity related to the state of the bearing 2, and can wirelessly transmit the detection results to the outside.

[0023] The generator 5 comprises a magnetic ring 6 arranged so as to be rotatable integrally with the rotating member 1, and a stator 7 radially opposed to the magnetic ring 6 across a magnetic gap, and the rotational motion of the rotating member 1 is electromagnetically converted into AC power by the magnetic ring 6 and the stator 7.

[0024] As shown in FIGS. 1 to 4, the sensor unit 4 has a storage section 8 that houses a circuit board 9, and a cover 10 that covers the circuit board 9.

[0025] 1, 2 and 5, the circuit board 9 is a printed circuit board on which the above-mentioned electric circuit is formed. The circuit board 9 has one or more sensors 11 that convert the above-mentioned physical or chemical quantities into electric signals, a wireless communication circuit 12 that transmits the detection results of the sensors 11, and a power supply circuit 13 that converts the above-mentioned AC power into DC power. These sensors 11 and the like are surface-mounted on one surface of a printed wiring board that is short in the radial direction and long in the circumferential direction and has a circular arc plate shape.

[0026] The sensor 11 is, for example, an acceleration sensor that detects radial or axial acceleration to monitor vibrations of the bearing 2, or a temperature sensor to monitor the temperature of the bearing 2. An electronic component including an acceleration sensor and a temperature sensor may be implemented as the sensor 11, or the acceleration sensor and the temperature sensor may be implemented as separate electronic components. When an acceleration sensor is used, it is preferable not to bring the acceleration sensor into contact with other members such as a sealant, in order to accurately detect vibrations caused by the bearing 2 with the sensor.

[0027] The wireless communication circuit 12 is a communication circuit that converts predetermined information, such as the detection result by the sensor 11, into radio waves and radiates the radio waves from an antenna. The wireless communication circuit 12 complies with a predetermined communication protocol and is generally modular. In order to avoid a decrease in wireless communication performance, it is preferable not to bring the antenna of the wireless communication circuit 12 into contact with other members, such as a sealant.

[0028] The power supply circuit 13 converts AC power generated in the stator 7 as the magnetic ring 6 rotates into DC power used in the circuit board 9, and supplies it to the sensor 11, the wireless communication circuit 12, etc. A battery may be stored in the storage section 8 as a backup power source for the generator 5.

[0029] The storage section 8 is a recess that forms an open space on one side of the sensor unit 4. The storage section 8 has a depth and a bottom area sufficient to accommodate the entire circuit board 9.

[0030] The aforementioned rotating member 1, as shown in Figures 2, 3 and 6, is composed of a first raceway ring arranged as a rotating ring. The mating member 3 is composed of a second raceway ring arranged as a stationary ring. The bearing 2 is a rolling bearing having two or more rolling elements 14 between a raceway surface 1a formed on the rotating member 1 and a raceway surface 3a formed on the mating member 3. These rolling elements 14 are held at equal intervals in the circumferential direction by a cage 15. The cage 15 is a crown-shaped cage having a ring portion only on the side opposite the sensor unit 4 (the side farther from the sensor unit 4, the left side in Figures 2 and 6) with respect to the rolling elements 14.

[0031] Bearing 2 is a radial bearing. Bearing 2 is also a standard bearing that complies with a specific standard. Here, a standard bearing refers to a bearing that satisfies the dimensions specified in the ISO or JIS standard. For example, the dimensions of radial bearings other than tapered roller bearings are specified in ISO15 or JIS B 1512-1.

[0032] Although the bearing 2 is configured as a deep groove ball bearing, the bearing 2 is not limited to a deep groove ball bearing. Also, the rotating member and the mating member are not limited to raceways, and can be configured as, for example, an inner ring spacer, an outer ring spacer, etc.

[0033] The magnetic ring 6 is a rotor that generates a rotating magnetic field for the stator 7. The magnetic ring 6 is fixed to the rotating member 1. The stator 7 of the generator 5 is a stator that guides the magnetic flux emitted from the magnetic ring 6 through a yoke 16 and induces an AC voltage in a coil 17.

[0034] The magnetic ring 6 has a magnet 18 magnetized with alternating north and south poles in the circumferential direction, and a core metal 19 that radially supports the peripheral surface of the magnet 18 on the side opposite the stator 7 (the peripheral surface on the side farther from the stator 7, the lower peripheral surface in FIG. 2, and the upper peripheral surface in FIG. 6). The magnet 18 is formed of magnetic rubber that extends in the circumferential direction. The magnet 18 is bonded to the core metal 19. Vulcanization bonding can be used as the bonding method.

[0035] 7 and 8, the stator 7 is made up of a yoke 16 and a coil 17. The yoke 16 and the coil 17 are disposed at positions facing the magnetic ring 6 in the radial direction.

[0036] 6 and 7, the yoke 16 is composed of first claw pole portion 16a and second claw pole portion 16b arranged alternately at intervals in the circumferential direction, a first side wall portion 16c extending radially from the first claw pole portion 16a toward the antimagnetic ring 6 (the side farther from the magnetic ring 6, the lower side in FIG. 6), a second side wall portion 16d extending radially from the second claw pole portion 16b toward the antimagnetic ring 6, and a connecting wall portion 16e extending between the first side wall portion 16c and the second side wall portion 16d with a finite length in the circumferential direction. The first claw pole portion 16a and the second claw pole portion 16b are located in a position radially opposite to the connecting wall portion 16e, and the first side wall portion 16c and the second side wall portion 16d are opposite to each other in the axial direction.

[0037] The coil 17 is wound around the connecting wall portion 16e to have a first coil portion 17a that passes circumferentially between the first side wall portion 16c and the second side wall portion 16d, and a second coil portion 17b that passes circumferentially through a position on the anti-magnetic ring 6 side (lower side in Figure 6) of the connecting wall portion 16e.

[0038] The yoke 16 is made up of a first magnetic member 20 and a second magnetic member 21 provided with a finite length in the circumferential direction.

[0039] As shown in Figures 5 and 6, the first magnetic material member 20 has, integrally and seamlessly, an annular side plate portion 20a including a first side wall portion 16c, a first claw pole portion 16a extending from the magnetic ring 6 side of the annular side plate portion 20a (the side closer to the magnetic ring 6, the upper side in Figure 6) to one axial side (the right side in Figures 5 and 6), a circumferential plate portion 20b extending from the magnetic ring 6 side of the annular side plate portion 20a to one axial side and extending a finite length in the circumferential direction on the same circumference as the first claw pole portion 16a, and an annular plate portion 20c extending from the anti-magnetic ring 6 side of the annular side plate portion 20a (the lower side in Figure 6) to one axial side.

[0040] The second magnetic material member 21 has a second side wall portion 16d, a second claw pole portion 16b extending from the magnetic ring 6 side of the second side wall portion 16d to the other axial side (left side in Figures 5 and 6), and a connecting wall portion 16e extending from the anti-magnetic ring 6 side of the second side wall portion 16d (lower side in Figure 6), which are seamlessly integrated with each other.

[0041] Each of the magnetic members 20 and 21 is formed from a single magnetic plate such as a steel plate, etc. The overall shape of each of the magnetic members 20 and 21 is formed by press molding.

[0042] The annular plate portion 20c, the circumferential plate portion 20b, and the annular side plate portion 20a form the storage portion 8. The outer periphery of the sensor unit 4 is formed by the annular plate portion 20c, and the inner periphery of the sensor unit 4 is formed by the circumferential plate portion 20b, the first claw pole portion 16a, and the second claw pole portion 16b.

[0043] It is also possible to omit the circumferential plate portion 20b. The circumferential plate portion 20b made of a magnetic material serves as a magnetic shield that suppresses the influence of the magnetic field of the magnetic ring 6 on the sensor 11, the wireless communication circuit 12, etc., so it is preferable to arrange the sensor 11, the wireless communication circuit 12, etc. between the circumferential plate portion 20b and the annular plate portion 20c.

[0044] Holes 20d penetrating between both side surfaces of the annular side plate portion 20a are formed at multiple locations in the circumferential direction. The connecting wall portion 16e has multiple protrusions that fit into the inner surfaces of the holes 20d extending in an arc shape in the circumferential direction, and most of the portion other than these protrusions is butted against the annular side plate portion 20a in the axial direction.

[0045] The sensor unit 4 has an arc-shaped bobbin 22 stacked on the annular side plate portion 20a in the axial direction. The arc-shaped bobbin 22 has a first groove portion 22a that radially supports the first coil portion 17a, a second groove portion 22b that radially supports the second coil portion 17b, and a partition portion 22d that forms a slit 22c that penetrates in the axial direction between the first groove portion 22a and the second groove portion 22b, all of which are seamlessly integrated. The first groove portion 22a, the second groove portion 22b, the slit 22c, and the partition portion 22d are parallel to each other along the circumferential direction. The entire arc-shaped bobbin 22 is formed of resin.

[0046] The arc-shaped bobbin 22 is in contact along the annular plate portion 20c over its entire circumferential length, and is also in contact with each of the first claw pole portions 16a in the radial direction. Due to these contacts, the arc-shaped bobbin 22 is positioned radially relative to the first magnetic member 20 so that the slits 22c and the holes 20d communicate with each other in the axial direction. The connecting wall portion 16e passes through the slits 22c and reaches the annular side plate portion 20a.

[0047] The arc-shaped bobbin 22 radially covers the slits formed between both circumferential ends of the circumferential plate portion 20b, specifically, the slits between the circumferential ends of the circumferential plate portion 20b and the first claw pole portion 16a or the second claw pole portion 16b, and the slits between the circumferentially adjacent claw pole portions 16a and 16b from the antimagnetic ring 6 side, and generally closes these slits. Therefore, the arc-shaped bobbin 22 contributes to preventing foreign matter from entering the stator 7 through these slits. When protecting the coil 17 for the purposes of insulation, heat resistance, dustproofing, moistureproofing, and friction prevention, a varnish treatment may be adopted in which the coil 17 is dipped in varnish or coated by dripping varnish onto the coil 17. It is also possible to omit the arc-shaped bobbin 22 and adopt an insulating-coated coil, which is then wound directly around the connecting wall portion 16e.

[0048] As shown in Figures 6, 8, and 9, the first claw pole portion 16a and the second claw pole portion 16b face each other in the radial direction with an air gap between them and the magnet 18. The first claw pole portion 16a and the second claw pole portion 16b are arranged in opposite directions in the axial direction and are arranged alternately in the circumferential direction. A circumferential air gap is formed between the first claw pole portion 16a and the second claw pole portion 16b that are adjacent in the circumferential direction. The total number of the first claw pole portions 16a and the second claw pole portions 16b is the same as the number of poles of the magnet 18 (the total number of N poles and S poles).

[0049] The magnetic flux from the N pole of the magnet 18, for example, enters the first side wall 16c (or the second side wall 16d) from the first claw pole portion 16a (or the second claw pole portion 16b), which is a magnetic pole, and then passes through the connecting wall portion 16e to reach the second side wall 16d (or the first side wall portion 16c), goes around the first coil portion 17a of the coil 17, and returns to the S pole of the magnet 18 via the adjacent second claw pole portion 16b (or the first claw pole portion 16a). When the positions of the N pole and the S pole of the magnet 18 are switched with the rotation of the rotating member 1, the direction of the magnetic flux is reversed. The alternating magnetic field thus generated generates an AC voltage at both ends of the start and end of the winding of the coil 17. Although a radial type claw pole type generator has been exemplified as the generator 5, it is possible to change to another type of generator.

[0050] Since the radial gap fluctuation between the magnetic ring 6 fixed to the rotating member 1, which is a component of the radial bearing, and the stator 7 of the sensor unit 4 fixed to the mating member 3, which is a component of the bearing 2, is small, a stable amount of power can be generated by the generator 5. That is, the rattle of the retainer 15 (expansion of the pocket clearance) that occurs with the passage of time of use of the bearing 2 usually tends to be larger in the axial direction than in the radial direction. In the case of a generator in which the magnetic ring and the stator face each other in the axial direction, the rattle of the retainer that occurs with the passage of time of use of the bearing tends to cause the axial air gap between the magnetic ring and the stator to vary. If the air gap becomes large, there is a concern that the amount of power generation will decrease, affecting the operation of electronic components such as sensors, and if the air gap becomes small, there is a concern that the magnetic ring and the stator of the sensor unit will come into contact with each other.

[0051] As shown in Figs. 7 and 8, the stator 7 is provided with a finite length in the circumferential direction, so the amount of power generated is smaller than when the stator is provided around the entire circumference in the circumferential direction. In order to increase the amount of power generated, it is preferable to increase the magnetic strength of the magnet 18. For example, as the magnet 18 of the magnetic ring 6, it is preferable to adopt a magnetic rubber in which rare earth magnetic powder (e.g., samarium-based Sm-Fe-N) with a high magnetic flux density is kneaded into rubber, or to adopt a sintered rare earth magnet (e.g., neodymium magnet). This "finite length of the stator 7 in the circumferential direction" is determined by the size of the circuit board 9 and the amount of power generation required. First, the installation space for the circuit board 9 is secured, and then the length of the stator 7 is determined according to the amount of power generation required. Specifically, it is about 90° to 180°.

[0052] The circuit board 9 including the sensor 11, the wireless communication circuit 12, and the power supply circuit 13 is housed between the annular plate portion 20c and the circumferential plate portion 20b. That is, the storage section 8 is formed by the annular side plate portion 20a, the circumferential plate portion 20b, and the annular plate portion 20c. The storage space of the storage section 8 (the space surrounded on three sides in the radial and axial directions by the plate portions 20a to 20c) is circumferentially connected to the space housing the coil 17. An insulating sheet 23 (see FIG. 5) such as a polyimide film is sandwiched between the circuit board 9 and the annular side plate portion 20a.

[0053] 7, both ends of the coil 17 are connected to terminals 24 provided on one surface of the circuit board 9. The input terminals of the power supply circuit 13 are the terminals 24. The power supplies of the sensor 11 and the wireless communication circuit 12 are the output terminals of the power supply circuit 13.

[0054] In addition, a battery may be stored in the storage section 8 and the battery may be charged by the generator 5, or the DC power of the battery may be supplied to the power supply circuit 13 in an emergency when power generation by the generator 5 is insufficient or stops.

[0055] As shown in Fig. 3 to Fig. 5, the cover 10 is provided in an arc shape that fits between the annular plate portion 20c and the circumferential plate portion 20b. The cover 10 is made of a non-metallic material. The cover 10 is formed, for example, of a resin that does not contain metal. Since the cover 10 is made of a non-metallic material that is radio wave transparent, it is possible to perform wireless communication using the antenna 12a of the wireless communication circuit 12 even if the storage portion 8 is formed of a magnetic material.

[0056] Note that the cover 10 may be made of a metal material in other portions as long as the portion facing the antenna 12a of the wireless communication circuit 12 is made of a nonmetallic material. When the circumferential plate portion 20b is omitted, in order to protect the circuit board 9, a portion equivalent to the circumferential plate portion 20b may be added to the cover 10 so as to close with the annular side plate portion 20a.

[0057] As shown in Fig. 2, the cover 10 and the wireless communication circuit 12 are separated from each other, and a gas layer is formed between them. If the dielectric comes into contact with the antenna 12a (see Fig. 5), there is a concern that the radio wave intensity of a certain frequency will be attenuated due to wavelength shortening, resulting in a deterioration in wireless communication performance. By forming a gas layer (generally an air layer) between the antenna 12a and the cover 10, the deterioration in wireless communication performance can be suppressed.

[0058] If there is no such concern, instead of the cover 10, the storage section 8 shown in FIG. 7 may be filled with a sealant to bury the circuit board 9. If it is desired to seal the storage section 8 while providing a gas layer, the sealant may be filled in the gap of the fitting section between the cover 10 and the storage section 8 shown in FIG. 2. The sealant may be a liquid that can be filled by application or injection and is fixed by hardening of the resin component. A low dielectric constant sealant is preferable, but a known sealant or potting material may be used. For example, an epoxy adhesive, a silicon sealant, a liquid gasket, an epoxy resin, a urethane resin epoxy resin, or the like may be used as the sealant.

[0059] 7, the second coil portion 17b of the coil 17 is covered by a stator cover 25 so as not to be exposed on one side of the sensor unit 4, as shown in Figures 3, 5 and 9. The stator cover 25 is fitted between both circumferential ends of the annular plate portion 20c and the circumferential plate portion 20b, both circumferential ends of the cover 10, and the second side wall portion 16d.

[0060] The stator cover 25 is made of a metal plate. Even if noise is electromagnetically radiated from the second coil portion 17b of the coil 17, the metal stator cover 25 serves as an electromagnetic shield that suppresses the diffusion of the noise to the outside of the sensor unit 4.

[0061] Instead of using the two members, the cover 10 and the stator cover 25, it is also possible to form both the cover 10 and the stator cover 25 into a single seamless member (eg, made of resin).

[0062] Incidentally, instead of the stator cover 25, the second coil portion 17b and the like may be covered with the above-mentioned sealing material so that the coil 17 is not exposed.

[0063] In assembling the sensor unit 4, the coil 17 is wound around the partition portion 22d of the arc-shaped bobbin 22 shown in Fig. 5 in advance, and then passed between the annular plate portion 20c and the first claw pole portion 16a of the first magnetic member 20 and placed on the annular side plate portion 20a. At this time, the slits 22c of the arc-shaped bobbin 22 and each hole 20d communicate with each other in the axial direction.

[0064] Next, the second magnetic member 21 is combined with the first magnetic member 20 in the axial direction as shown in Figs. 6 and 7. At this time, the connecting wall portion 16e of the second magnetic member 21 is passed through the slits 22c of the arc-shaped bobbin 22, and each protrusion of the connecting wall portion 16e is fitted into the corresponding hole 20d of the first magnetic member 20, and the portion other than the protrusion is butted against the annular side plate portion 20a in the axial direction. This fitting ensures that the first magnetic member 20 and the second magnetic member 21 are coaxial, and the first claw pole portion 16a and the second claw pole portion 16b are alternately arranged in a predetermined phase with a gap in the circumferential direction. Therefore, the first magnetic member 20 and the second magnetic member 21 can be combined appropriately without using a jig. When the first magnetic member 20 and the second magnetic member 21 are combined as described above, a storage portion 8 that is open between the annular side plate portion 20c and the circumferential plate portion 20b is formed.

[0065] The fixing means for fixing the projection of the connection wall portion 16e to the hole 20d may be, for example, press-fitting, adhesion, laser welding, or a suitable combination of these.

[0066] It is preferable that the hole 20d and the protrusions of the connection wall 16e are formed at three or more locations spaced apart in the circumferential direction. When the arc-shaped bobbin 22 is omitted, the hole 20d and the protrusions of the connection wall 16e can also be omitted. In this case, the butt portions of the annular side plate and the connection wall may be fixed by adhesive, laser welding, or the like, in a state in which the first magnetic member and the second magnetic member are coaxially aligned and phase-aligned using a jig (not shown).

[0067] Also, the insulating sheet 23 and the circuit board 9 are placed on the annular side plate portion 20a shown in FIG. 5. At this time, the insulating sheet 23 is fixed to the annular side plate portion 20a with an adhesive. Furthermore, of both sides of the circuit board 9, the side opposite to the mounting surface of electronic components such as the sensor 11 is made to face the annular side plate portion 20a, and the circuit board 9 is fixed to the insulating sheet 23 with an adhesive. With this fixing, as shown in FIG. 7 to FIG. 9, the entire circuit board 9 including the sensor 11, the wireless communication circuit 12, and the power supply circuit 13 and the stator 7 are arranged on the same circumference in the circumferential direction. The circuit board 9 and the insulating sheet 23 may be fixed by appropriately using adhesive, screwing, or the like. Either before or after this fixing, both ends of the coil 17 and the terminals 24 of the circuit board 9 are soldered.

[0068] Thereafter, the cover 10 and the stator cover 25 shown in Fig. 5 are fixed to the first magnetic member 20 as shown in Fig. 3. The cover 10 is fitted between the annular plate portion 20c and the circumferential plate portion 20b. The stator cover 25 is fitted between the annular plate portion 20c, the circumferential plate portion 20b and the second side wall portion 16d. These fixings may be performed by appropriately using press fitting, adhesion, screw fastening, etc. By fixing the cover 10, the space between the cover 10 and the antenna 12a becomes filled with air.

[0069] The completed sensor unit 4 and magnetic ring 6 are attached to the corresponding mating member 3 or rotating member 1 so that they have no portions protruding axially or radially from the bearing 2, as shown in Figures 2, 6 and 9, respectively.

[0070] The rotating member 1 and the mating member 3 have stepped ends 1b, 3b that face each other in the radial direction, as shown in Fig. 2. The stepped ends 1b, 3b are formed to enlarge the annular space between the rotating member 1 and the mating member 3 at one end of both 1, 3, thereby making it possible to arrange the sensor unit 4 and the magnetic ring 6 facing each other in the radial direction.

[0071] The annular plate portion 20c of the sensor unit 4 is fitted into the stepped end portion 3b of the counterpart member 3. The annular plate portion 20c can be fixed to the stepped end portion 3b of the counterpart member 3 by one or more suitable means such as press-fitting, adhesion, or spot welding using a laser.

[0072] The magnetic ring 6 is fitted onto the stepped end 1b of the rotating member 1. The magnetic ring 6 can be fixed to the stepped end 1b of the rotating member 1 by suitable means such as press fitting or adhesion.

[0073] By fixing the sensor unit 4 and the magnetic ring 6 to the corresponding stepped end 3b of the mating member 3 or the stepped end 1b of the rotating member 1, the rotating member 1, the mating member 3, the sensor unit 4, and the magnetic ring 6 are arranged coaxially.

[0074] A certain distance or more is secured between the sensor unit 4 and the rolling elements 14 and the cage 15. This distance is set so that the sensor unit 4 does not come into contact with the rolling elements 14 and the cage 15 even if there is axial displacement due to the gap inside the bearing.

[0075] 2, 6, and 9, the sensor unit 4 and the magnetic ring 6 are arranged in a positional relationship in which they do not overlap each other in the axial direction but face each other in the radial direction. Therefore, the axial width of the space required for arranging the sensor unit 4 and the magnetic ring 6 can be smaller than when the sensor unit 4 and the magnetic ring 6 are overlapped in the axial direction.

[0076] 1, 7 and 8, since the stator 7 is provided with a finite length in the circumferential direction, the stator 7, the sensor 11, the wireless communication circuit 12, and the power supply circuit 13 can be arranged on the same circumference. With this arrangement, the stator 7, the sensor 11, the wireless communication circuit 12, and the power supply circuit 13 can be arranged in the same axial position without increasing the outer diameter of the sensor unit 4, thereby reducing the axial width of the sensor unit 4.

[0077] That is, in order to arrange electronic components having a large mounting area such as the wireless communication circuit 12 including the antenna 12a and the power supply circuit 13 including a rectifier circuit section, etc., there is a limit to reducing the radial width of the circuit board on which these components are mounted. If the yoke 16 of the stator 7 is provided on the entire circumference as in the past, the radial width of the space required for arranging the circuit board 9 on which the sensor 11, the wireless communication circuit 12, etc. are mounted cannot be secured unless the outer diameter of the sensor unit 4 is enlarged, and therefore the stator 7 and the sensor 11, etc. cannot be arranged at the same axial position. On the other hand, if the outer diameter of the sensor unit 4 is enlarged, it becomes necessary to enlarge the annular space between the mating member 3 and the rotating member 1 in the radial direction accordingly. However, when a small bearing having an outer diameter of 80 mm or less is used as the bearing 2 in the standard bearing, the amount by which the annular space can be enlarged in the radial direction by the stepped ends 1b, 3b of the rotating member 1 and the mating member 3 is small as shown in Figs. 2 and 8, and the radial width of the space required for arranging the sensor 11, the wireless communication circuit 12, etc. cannot be secured.

[0078] In contrast, when the stator 7 is provided with a finite circumferential length as shown in Figures 1, 7, and 8, the radial width of the space available for arranging the sensor 11, wireless communication circuit 12, etc. in the circumferential region where the stator 7 is not arranged (corresponding to the radial distance between the annular plate portion 20c and the circumferential plate portion 20b in the illustrated example) is expanded by the radial width of the yoke 16, and the sensor 11, wireless communication circuit 12, etc. can be arranged on the same circumference as the stator 7 (i.e., at the same axial position) without expanding the outer diameter of the sensor unit 4. For this reason, even when a standard small-sized bearing is used as the bearing 2, as described above, if the axial width of the space required for arranging the sensor unit 4 and the magnetic ring 6 is reduced, and the axial width of the sensor unit 4 is reduced by arranging the stator 7, the sensor 11, the wireless communication circuit 12, etc. in the same axial position without increasing the outer diameter of the sensor unit 4, and the radial width of the annular space for arranging the sensor unit 4 and the magnetic ring 6 radially opposite each other is increased by the stepped ends 1b, 3b of the rotating member 1 and the mating member 3, the sensor unit 4 and the magnetic ring 6 can be arranged so that they do not protrude in the axial and radial directions from the bearing 2 configured as a standard small-sized bearing. Therefore, the axial width and inner and outer diameters of this bearing device can be made equivalent to the major dimensions of a standard small-sized bearing.

[0079] This bearing device is as described above (see Figures 1, 2, 6 to 9) and comprises a rotating member 1, a bearing 2 that rotatably supports the rotating member 1, a mating member 3 that is arranged coaxially with the rotating member 1, a sensor unit 4 attached to the mating member 3, and a generator 5 that converts the rotational motion of the rotating member 1 into AC power, wherein the sensor unit 4 houses a sensor 11, a wireless communication circuit 12 that transmits the detection results of the sensor 11, and a power supply circuit 13 that converts the AC power into DC power, and the generator 5 has a magnetic ring 6 that rotates integrally with the rotating member 1 and a stator 7 provided on the sensor unit 4, and the magnetic ring 6 and the stator 7 are arranged in positions that are radially opposite each other.

[0080] In particular, this bearing device has a stator 7 that is provided at a finite length in the circumferential direction, and the stator 7, sensor 11, wireless communication circuit 12, and power supply circuit 13 are arranged on the same circumference, so that the width of the sensor unit 4 can be reduced while avoiding an increase in the diameter of the sensor unit 4, thereby reducing the space required for arranging the sensor unit 4 and the magnetic ring 6.

[0081] Thus, in this bearing device, in which the magnetic ring 6 is attached to the rotating member 1, the sensor unit 4 provided with the sensor 11, wireless communication circuit 12, power supply circuit 13 and stator 7 is attached to the mating member 3, and the stator 7 and the magnetic ring 6 are arranged radially opposed to each other, the dimensions of the sensor unit 4 can be reduced, thereby making it possible to reduce the space required for arranging the sensor unit 4 and the magnetic ring 6. Furthermore, even in the case of a bearing 2 configured as a standard and small-sized bearing, it becomes easy to accommodate the sensor unit 4 and the magnetic ring 6 between the rotating member 1 and the mating member 3 so that they are radially opposed to each other.

[0082] In addition, in this bearing device, the stator 7 has a yoke 16 and a coil 17 arranged at a position radially facing the magnetic ring 6, the yoke 16 has first claw pole portions 16a and second claw pole portions 16b arranged alternately at a circumferential interval, a first side wall portion 16c extending radially from the first claw pole portion 16a toward the antimagnetic ring side, a second side wall portion 16d extending radially from the second claw pole portion 16b toward the antimagnetic ring side, and a connecting wall portion 16e extending between the first side wall portion 16c and the second side wall portion 16d with a finite length in the circumferential direction, and the coil 17 is wound around the connecting wall portion 16e to have a first coil portion 17a passing circumferentially between the first side wall portion 16c and the second side wall portion 16d and a second coil portion 17b passing circumferentially through a position on the antimagnetic ring 6 side with respect to the connecting wall portion 16e, thereby making it possible to provide a claw-pole type generator 5 with a finite length in the circumferential direction.

[0083] In addition, in this bearing device, the yoke 16 is composed of a first magnetic member 20 and a second magnetic member 21 provided with a finite length in the circumferential direction, and the first magnetic member 20 has an annular side plate portion 20a including a first side wall portion 16c, a first claw pole portion 16a extending from the magnetic ring 6 side of the annular side plate portion 20a to one side in the axial direction, a circumferential plate portion 20b extending from the magnetic ring 6 side of the annular side plate portion 20a to one side in the axial direction and extending a finite length in the circumferential direction on the same circumference as the first claw pole portion 16a, and an annular plate portion 20c extending from the anti-magnetic ring 6 side of the annular side plate portion 20a to one side in the axial direction. Furthermore, the second magnetic material member 21 has a second side wall portion 16d, a second claw pole portion 16b extending from the magnetic ring 6 side of the second side wall portion 16d to the other axial direction side, and a connecting wall portion 16e extending from the anti-magnetic ring 6 side of the second side wall portion 16d to the other axial direction side, and the sensor 11, wireless communication circuit 12, and power supply circuit 13 are accommodated between the annular plate portion 20c and the circumferential plate portion 20b of the first magnetic material member 20. Therefore, with just two members, the first magnetic material member 20 and the second magnetic material member 21, the storage section 8 for accommodating the sensor 11 etc. and the yoke 16 can be provided on the same circumference.

[0084] In addition, in this bearing device, the sensor unit 4 has an arc-shaped bobbin 22 axially stacked on the annular side plate portion 20a, and the arc-shaped bobbin 22 has a first groove portion 22a that radially supports the first coil portion 17a, a second groove portion 22b that radially supports the second coil portion 17b, and a partition portion 22d that forms a slit 22c that penetrates in the axial direction between the first groove portion 22a and the second groove portion 22b, and the connecting wall portion 16e reaches the annular side plate portion 20a through the slit 22c, so that it is possible to achieve both the support of the arc-shaped bobbin 22 to keep the coil 17 in a form that is wound around the connecting wall portion 16e, and the provision of a yoke 16 by combining the first magnetic member 20 and the second magnetic member 21.

[0085] In addition, in this bearing device, the rotating member 1 consists of a first raceway ring, the mating member 3 consists of a second raceway ring, and the bearing 2 is a rolling bearing having a rolling element 14 arranged between the rotating member 1 and the mating member 3, the rotating member 1 and the mating member 3 have stepped ends 1b, 3b that face each other in the radial direction, the magnetic ring 6 is fitted into the stepped end 1b of the rotating member 1 so that it does not protrude axially from the rotating member 1, and the sensor unit 4 is fitted into the stepped end 3b of the mating member 3 so that it does not protrude axially from the mating member 3.As a result, the annular space inside the bearing is expanded by the stepped ends 1b, 3b of the rotating member 1 and the mating member 3, and therefore the sensor unit 4 and the magnetic ring 6 can be accommodated in the bearing 2 without expanding the outer diameter of the bearing 2, and a compact bearing device can be realized.

[0086] A bearing device according to a second embodiment of the present invention is shown in Fig. 10. Note that, in the following, only the differences from the first embodiment will be described.

[0087] The bearing device according to the second embodiment is configured as a spindle that rotatably supports a rotating shaft 30 relative to a housing 31. A plurality of bearings 32, 33 are interposed between the rotating shaft 30 and the housing 31. A rotating member 34 configured as a rotating side spacer that maintains the axial distance between these bearings 32, 33, and a mating member 35 similarly configured as a stationary side spacer are housed between the rotating shaft 30 and the housing 31.

[0088] The bearings 32 and 33 are angular contact ball bearings which are standard and small bearings and have inner rings 32a and 33a, outer rings 32b and 33b, rolling elements 32c and 33c, and retainers 32d and 33d, respectively, and are arranged in a back-to-back configuration.

[0089] The rotating member 34 is sandwiched between the inner rings 32a, 33a in the axial direction. The inner and outer diameters of the rotating member 34 are equal to those of the inner rings 32a, 33a. The mating member 35 is sandwiched between the outer rings 32b, 33b in the axial direction. The inner and outer diameters of the mating member 35 are equal to those of the outer rings 32b, 33b.

[0090] The sensor unit 4 is fitted into a stepped end portion formed on a mating member 35. The magnetic ring 6 is fitted into a stepped end portion formed on a rotating member 34.

[0091] The rotating side spacer and stationary side spacer sandwiched between small bearings may not have large inner and outer diameters and axial widths because the load and bearing span are small. In such cases, the accommodation space for the sensor unit 4 and magnetic ring 6 is limited, just as in the case of attaching a sensor unit and a magnetic ring to the end of the raceway of a small bearing. As described above, because the dimensions of the sensor unit 4 are small, it is possible to accommodate the sensor unit 4 and magnetic ring 6 in a radially opposing arrangement between the rotating member 34 and the mating member 35, which are such spacers.

[0092] In each of the above-described embodiments, a bearing 2 having an outer ring as a stationary ring and an inner ring as a rotating ring has been exemplified, however, it is also possible for the outer ring to be a rotating ring and the inner ring to be a stationary ring, with a sensor unit attached to the inner ring which is a stationary ring, and a magnetic ring attached to the outer ring which is a rotating ring.

[0093] In addition, in each of the above-described embodiments, an example has been given of a case in which a magnetic ring is attached to a rotating ring or a rotating side spacer, but electricity can be generated if the rotating member and the mating member rotate relative to each other, and since the sensor unit is wireless, it is also possible for the rotating ring or the rotating side spacer to be the mating member to which the sensor unit is attached, and for the stationary ring or the stationary side spacer to be the rotating member to which the magnetic ring is attached.

[0094] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0095] 1, 34 Rotating member 2, 32, 33 Bearings 3, 35 Mating member 4 Sensor unit 5. Generator 6 Magnetic Ring 7 Stator 11 Sensors 12 Wireless communication circuits 13 Power circuit 14 Rolling elements 16 York 16a First claw pole part 16b Second claw pole part 16c First side wall 16d Second side wall 16e Connecting wall 17 Coil 17a First coil portion 17b Second coil section 20 First magnetic member 21 Second magnetic member 22 Arc-shaped bobbin 22a First groove 22b Second groove 22c slit 22d Partition

Claims

1. a rotating member, a bearing that rotatably supports the rotating member, a mating member that is arranged coaxially with the rotating member, a sensor unit that is attached to the mating member, and a generator that converts the rotational motion of the rotating member into AC power, the sensor unit accommodates a sensor, a wireless communication circuit that transmits a detection result of the sensor, and a power supply circuit that converts the AC power into DC power; the generator has a magnetic ring that rotates integrally with the rotating member and a stator provided in the sensor unit, In the bearing device, the magnetic ring and the stator are disposed at positions facing each other in a radial direction, A bearing device characterized in that the stator is provided with a finite length in the circumferential direction, and the stator, the sensor, the wireless communication circuit, and the power supply circuit are arranged on the same circumference.

2. the stator has a yoke and a coil arranged at a position radially opposed to the magnetic ring, the yoke has first and second claw pole portions alternately arranged at intervals in the circumferential direction, a first side wall portion extending radially from the first claw pole portion toward the antimagnetic ring side, a second side wall portion extending radially from the second claw pole portion toward the antimagnetic ring side, and a connecting wall portion extending between the first side wall portion and the second side wall portion with a finite length in the circumferential direction, 2. The bearing device according to claim 1, wherein the coil is wound around the connecting wall portion to have a first coil portion passing circumferentially between the first side wall portion and the second side wall portion, and a second coil portion passing circumferentially through a position on the antimagnetic ring side of the connecting wall portion.

3. the yoke comprises a first magnetic member and a second magnetic member provided with a finite length in the circumferential direction, the first magnetic member has an annular side plate portion including the first side wall portion, the first claw pole portion extending from a magnetic ring side of the annular side plate portion to one side in the axial direction, a circumferential plate portion extending from the magnetic ring side of the annular side plate portion to one side in the axial direction and extending a finite length in the circumferential direction on the same circumference as the first claw pole portion, and an annular plate portion extending from an anti-magnetic ring side of the annular side plate portion to one side in the axial direction, the second magnetic member has the second side wall portion, the second claw pole portion extending from a magnetic ring side of the second side wall portion to the other axial direction side, and the connecting wall portion extending from a antimagnetic ring side of the second side wall portion to the other axial direction side, The bearing device according to claim 2 , wherein the sensor, the wireless communication circuit, and the power supply circuit are housed between the annular plate portion and the circumferential plate portion of the first magnetic member.

4. the sensor unit has an arc-shaped bobbin stacked in the axial direction on the annular side plate portion, the arc-shaped bobbin has a first groove portion that radially supports the first coil portion, a second groove portion that radially supports the second coil portion, and a partition portion that forms a slit that penetrates in the axial direction between the first groove portion and the second groove portion, 4. The bearing device according to claim 3, wherein the connecting wall portion passes through the slit and reaches the annular side plate portion.

5. the rotating member is a first raceway ring, the mating member is a second raceway ring, and the bearing is a rolling bearing having rolling elements disposed between the rotating member and the mating member, The rotating member and the mating member have stepped ends that face each other in a radial direction, the magnetic ring is fitted to the stepped end of the rotary member so as not to protrude from the rotary member in the axial direction; 5. The bearing device according to claim 1, wherein the sensor unit is fitted onto a stepped end of the mating member so as not to protrude from the mating member in the axial direction.

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