Bearing device

Abstract

This bearing device has a magnetic ring attached to a rotary member, and has a sensor unit which is attached to a counterpart member and provided with a sensor, a wireless communication circuit, a power supply circuit, and a stator, resulting in the stator and the magnetic ring to oppose each other in the radial direction. In the bearing device, the space required for arranging the sensor unit and the magnetic ring is reduced by suppressing the size of the sensor unit. In the sensor unit (4), the stator (7) is provided at a finite length in the circumferential direction. The stator (7), the sensor (11), the wireless communication circuit (12), and a power supply circuit (13) are arranged on the same circumference.

Description

Bearing device

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

[0002] Conventionally, a known bearing device has been proposed in which a sensor and a wireless module for detecting the state 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 generator is connected to the rotating ring of the rolling bearing, the stator of the claw-pole generator is provided in the sensor unit, and the sensor unit is connected to the stationary ring of the rolling bearing (see, for example, Patent Document 1).

[0003] The bearing device disclosed in Patent Document 1 converts the rotational motion of a rotating ring relative to a stationary ring into AC power using a stator and magnetic ring that face each other in the radial direction. This AC power is then converted into DC power by a power supply circuit on a circuit board and supplied to a sensor and a wireless module, enabling wireless monitoring of the condition of the rolling bearing. In particular, the sensor and the stator are not aligned radially but are positioned at different positions in the axial direction, which allows the outer diameter of the sensor unit to 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 positioned radially opposite each other.

[0004] Japanese Patent Application Laid-Open No. 2022-156079

[0005] However, in the bearing device of Patent Document 1, the sensor and other components of the sensor unit and the stator are located at different axial positions, which results in a large axial width of the sensor unit. Therefore, if 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 range of 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 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 equipped with 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.

[0008] In order to solve the above problems, the present invention employs Configuration 1, 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 results 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 being positioned so as to face each other in the radial direction, wherein the stator is arranged to have 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.

[0009] As in the above-described configuration 1, the sensor unit is provided with a stator having a finite length in the circumferential direction, and the stator, sensor, wireless communication circuit, and power supply circuit are arranged on the same circumference, which makes it possible to reduce the axial width of the sensor unit 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 radially opposite the magnetic ring, the yoke having first and second claw pole portions alternately arranged at a circumferential interval, a first side wall portion extending radially from the first claw pole portion toward the antimagnetic ring, a second side wall portion extending radially from the second claw pole portion toward the antimagnetic ring, and a connecting wall portion extending a finite length in the circumferential direction between the first and second side wall portions, and the coil is wound around the connecting wall portion so as to have a first coil portion passing circumferentially between the first and second side wall portions and a second coil portion passing circumferentially at a position on the antimagnetic ring side of the connecting wall portion. According to this configuration 2, a claw-pole 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 anti-magnetic 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 anti-magnetic 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 housed between the annular plate portion and the circumferential plate portion of the first magnetic material member. According to this configuration 3, the storage section for accommodating the 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-described 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 having 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 the axial direction between the first groove portion and the second groove portion, and the connecting wall portion reaches the annular side plate portion through the slit. This configuration 4 can achieve both the support of the arc-shaped bobbin to keep the coil wound around the connecting wall portion and the provision of 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 comprises a first raceway ring, the mating member comprises a second raceway ring, 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 onto 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 onto 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 within the bearing without increasing the outer diameter of the bearing, and therefore a compact bearing device can be realized.

[0014] As described above, by adopting the above configuration 1, this invention makes it possible 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, a wireless communication circuit, a power supply circuit, and a stator are attached to a mating member, and the stator and magnetic ring are radially opposed.

[0015] 1 is a perspective view of a bearing device according to a first embodiment of the present invention with a cover removed; FIG. 2 is a longitudinal front view of the vicinity of the sensor unit of the bearing device of FIG. 1; FIG. 3 is an exploded perspective view of the bearing device of FIG. 1 with the sensor unit and magnetic ring removed; FIG. 4 is a perspective view of the sensor unit of the bearing device of FIG. 1 with covers attached; FIG. 5 is an exploded perspective view of the sensor unit of FIG. 1; FIG. 6 is a longitudinal front view of the vicinity of the stator of the sensor unit of FIG. 1;

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

[0017] As shown in Figures 1 to 3, this bearing device comprises 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 relative to the mating member 3 in the circumferential direction.

[0020] The bearing 2 is a mechanism that supports the rotating member 1 so that it can rotate freely in the circumferential direction.

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

[0022] The sensor unit 4 is a unit that incorporates an electrical circuit that uses a generator 5 as a power source to detect at least one of physical and chemical quantities related to the state of the bearing 2 and wirelessly transmits the detection results to the outside.

[0023] The generator 5 comprises a magnetic ring 6 arranged to rotate 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 housing 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 aforementioned electric circuits are formed. The circuit board 9 has one or more sensors 11 that convert the aforementioned 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 aforementioned AC power into DC power. These sensors 11 and the like are surface-mounted on one surface of a circular arc-shaped printed wiring board that is short in the radial direction and long in the circumferential direction.

[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 that monitors 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 that the acceleration sensor not come into contact with other components 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 results of the sensor 11, into radio waves and radiates the radio waves from an antenna. The wireless communication circuit 12 conforms to a predetermined communication protocol and is generally modular. To avoid a decrease in wireless communication performance, it is preferable that the antenna of the wireless communication circuit 12 not come 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 on the circuit board 9, and supplies it to the sensor 11, wireless communication circuit 12, etc. A battery may be housed 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 that are sufficient to accommodate the entire circuit board 9.

[0030] As shown in Figures 2, 3, and 6, the rotating member 1 described above comprises a first raceway ring disposed as a rotating ring. The mating member 3 comprises a second raceway ring disposed 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 from the rolling elements 14 (the side farther from the sensor unit 4, the left side in Figures 2 and 6).

[0031] The bearing 2 is a radial bearing. The 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 an ISO or JIS standard. For example, the dimensions of radial bearings other than tapered roller bearings are specified in ISO 15 or JIS B 1512-1.

[0032] Although the example has been given in which the bearing 2 is configured as a deep groove ball bearing, the bearing 2 is not limited to a deep groove ball bearing. Furthermore, 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 magnets 18 magnetized with alternating north and south poles in the circumferential direction, and a core 19 that radially supports the circumferential surface of the magnet 18 on the side opposite the stator 7 (the circumferential surface on the side farther from the stator 7, the lower circumferential surface in FIG. 2 and the upper circumferential 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 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 in positions facing the magnetic ring 6 in the radial direction.

[0036] 6 and 7, the yoke 16 comprises first and second claw pole portions 16a, 16b alternately arranged at intervals in the circumferential direction, a first side wall portion 16c extending radially from the first claw pole portion 16a toward the diamagnetic ring 6 (the side farther from the magnetic ring 6, or the lower side in FIG. 6), a second side wall portion 16d extending radially from the second claw pole portion 16b toward the diamagnetic ring 6, and a connecting wall portion 16e spanning a finite length in the circumferential direction between the first and second side wall portions 16c, 16d. The first and second claw pole portions 16a, 16b are positioned radially opposite the connecting wall portion 16e, and the first and second side wall portions 16c, 16d are opposed to each other in the axial direction.

[0037] The coil 17 is wound around the connecting wall portion 16e so as 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 at 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 member 20 has, seamlessly and integrally, 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 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 toward 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) toward the other axial side, all of which are seamlessly integrated.

[0041] Each of the magnetic members 20 and 21 is formed from a single magnetic plate such as a steel plate, and 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] The circumferential plate portion 20b may be omitted. 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 area other than these protrusions is abutted against the annular side plate portion 20a in the axial direction.

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

[0046] The arc-shaped bobbin 22 contacts the annular plate portion 20c along its entire circumferential length and also contacts each of the first claw pole portions 16a in the radial direction. These contacts position the arc-shaped bobbin 22 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 the 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, thereby substantially closing these slits. Therefore, the arc-shaped bobbin 22 contributes to preventing foreign matter from entering the stator 7 through these slits. To protect the coil 17 for insulation, heat resistance, dust resistance, moisture resistance, and friction prevention, a varnish treatment may be employed, in which the coil 17 is immersed in varnish or coated by dripping varnish onto the coil 17. Alternatively, the arc-shaped bobbin 22 may be omitted, and an insulating-coated coil may be used and 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 alternately arranged 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 first claw pole portions 16a and second claw pole portions 16b is the same as the number of poles of the magnet 18 (the total number of north and south poles).

[0049] The magnetic flux emanating from the north pole of the magnet 18 passes, for example, from the first claw pole portion 16a (or the second claw pole portion 16b), which is a magnetic pole, into the first side wall portion 16c (or the second side wall portion 16d), passes through the connecting wall portion 16e, and reaches the second side wall portion 16d (or the first side wall portion 16c), circulates around the first coil portion 17a of the coil 17, passes through the adjacent second claw pole portion 16b (or the first claw pole portion 16a), and returns to the south pole of the magnet 18. When the north and south poles of the magnet 18 switch positions as the rotating member 1 rotates, the direction of the magnetic flux reverses. The alternating magnetic field thus generated generates an alternating voltage at both ends of the coil 17, at the beginning and end of the winding. While a radial-type claw pole generator has been illustrated as the generator 5, other types of generators may be used.

[0050] Because there is little variation in the radial gap 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, the generator 5 can ensure a stable amount of power generation. That is, the play (expansion of pocket clearance) of the cage 15 over time when the bearing 2 is in use typically tends to be larger in the axial direction than in the radial direction. In a generator in which the magnetic ring and the stator face each other in the axial direction, the play of the cage over time when the bearing is in use tends to cause the axial air gap between the magnetic ring and the stator to vary. If the air gap becomes larger, there is a concern that the amount of power generation will decrease, affecting the operation of electronic components such as sensors. If the air gap becomes smaller, 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 Figures 7 and 8, the stator 7 is provided with a finite length in the circumferential direction, resulting in a lower amount of power generation compared to when the stator is provided around the entire circumference. To increase the amount of power generation, it is advisable to increase the magnetic strength of the magnets 18. For example, the magnets 18 of the magnetic ring 6 may be made of magnetic rubber in which rare-earth magnetic powder with high magnetic flux density (e.g., samarium-based Sm—Fe—N) is kneaded into rubber, or 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 required amount of power generation. First, ensure sufficient installation space for the circuit board 9, and then determine the length of the stator 7 based on the required amount of power generation. Specifically, it is approximately 90° to 180°.

[0052] The circuit board 9, which includes the sensor 11, wireless communication circuit 12, and 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 that houses 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 for 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 the power generation by the generator 5 is insufficient or stops.

[0055] As shown in Figures 3 to 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. For example, the cover 10 is formed of a resin that does not contain metal. Because the cover 10 is made of a non-metallic material that is radio wave transparent, wireless communication using the antenna 12a of the wireless communication circuit 12 is possible even if the storage portion 8 is formed of a magnetic material.

[0056] The cover 10 may be formed of a metallic material in other portions as long as the portion facing the antenna 12a of the wireless communication circuit 12 is formed of a non-metallic material. Furthermore, if the circumferential plate portion 20b is omitted, a portion corresponding to the circumferential plate portion 20b may be added to the cover 10 so as to fit together with the annular side plate portion 20a in order to protect the circuit board 9.

[0057] As shown in Fig. 2, the cover 10 and the wireless communication circuit 12 are separated by a gas layer. 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 providing a gas layer (generally an air layer) between the antenna 12a and the cover 10, it is possible to suppress the deterioration in wireless communication performance.

[0058] If this is not a concern, the storage section 8 shown in FIG. 7 may be filled with a sealant to bury the circuit board 9, instead of the cover 10. Furthermore, if it is desired to seal the storage section 8 while providing a gas layer, the sealant may be filled in the gap between the mating portion of the cover 10 and the storage section 8 shown in FIG. 2. Any sealant may be used as long as it is liquid and can be applied or injected and is fixed by hardening of the resin component. A low dielectric constant sealant is preferred, but known sealants and potting materials can also be used. For example, epoxy adhesives, silicone sealants, liquid gaskets, epoxy resins, urethane resin epoxy resins, etc. can 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 FIGS. 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 electromagnetic noise is generated from the second coil portion 17b of the coil 17, the metal stator cover 25 acts as an electromagnetic shield that suppresses the diffusion of the noise to the outside of the sensor unit 4.

[0061] Instead of using the cover 10 and the stator cover 25 as two members, the cover 10 and the stator cover 25 may be formed into a single seamless member (for example, made of resin).

[0062] 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] 5, the coil 17 is wound around the partition portion 22d of the arc-shaped bobbin 22, and then the coil 17 is passed between the annular plate portion 20c of the first magnetic member 20 and the first claw pole portion 16a and placed on the annular side plate portion 20a. At this time, the slits 22c of the arc-shaped bobbin 22 and the holes 20d are in axial communication with each other.

[0064] Next, the second magnetic member 21 is axially assembled with the first magnetic member 20 as shown in Figures 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 protrusions is axially butted against the annular side plate portion 20a. This fitting ensures that the first magnetic member 20 and the second magnetic member 21 are coaxially aligned, and the first claw pole portions 16a and the second claw pole portions 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 assembled appropriately without using a jig. When the first magnetic member 20 and the second magnetic member 21 are assembled as described above, an open storage section 8 is formed between the annular side plate portion 20c and the circumferential plate portion 20b.

[0065] The fixing means for fixing the projection of the connecting wall portion 16e to the hole 20d may be, for example, press-fitting, adhesive, laser welding, or an appropriate combination of these.

[0066] Preferably, the hole 20d and the protrusions of the connecting wall 16e are formed in three or more locations spaced apart in the circumferential direction. Furthermore, if the arc-shaped bobbin 22 is omitted, the hole 20d and the protrusions of the connecting wall 16e can also be omitted. In this case, the first and second magnetic members may be aligned coaxially and in phase using a jig (not shown), and the butting portions of the annular side plate and the connecting wall may be fixed by adhesive, laser welding, or the like.

[0067] The insulating sheet 23 and circuit board 9 are placed on the annular side plate 20a shown in FIG. 5 . The insulating sheet 23 is then fixed to the annular side plate 20a with adhesive. The surface of the circuit board 9 opposite the mounting surface for electronic components such as the sensor 11 faces the annular side plate 20a, and the circuit board 9 is fixed to the insulating sheet 23 with adhesive. As a result of this fixing, the entire circuit board 9 including the sensor 11, wireless communication circuit 12, and power supply circuit 13 and the stator 7 are arranged on the same circumference in the circumferential direction, as shown in FIGS. 7 to 9 . The circuit board 9 and insulating sheet 23 may be fixed using adhesive, screws, or other suitable means. Either before or after this fixing, both ends of the coil 17 are soldered to the terminals 24 of the circuit board 9.

[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 may be fixed by press-fitting, adhesive, screwing, or the like as appropriate. 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 do not have any portions that protrude axially or radially from the bearing 2, as shown in Figures 2, 6, and 9, respectively.

[0070] 2, the rotating member 1 and the mating member 3 have stepped ends 1b, 3b that face each other in the radial direction. 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 each of the rotating member 1 and the mating member 3, thereby enabling the sensor unit 4 and the magnetic ring 6 to be disposed 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 mating member 3. The annular plate portion 20c can be fixed to the stepped end portion 3b of the mating member 3 by one or more suitable means such as press-fitting, adhesive bonding, or laser spot welding.

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

[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 cage 15. This distance is set so that the sensor unit 4 does not come into contact with the rolling elements 14 and cage 15 even if there is axial displacement due to clearance inside the bearing.

[0075] 2, 6, and 9, the sensor unit 4 and the magnetic ring 6 are arranged so as to face each other in the radial direction without overlapping each other in the axial direction. Therefore, the axial width of the space required to arrange 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, the stator 7 is provided with a finite length in the circumferential direction, so the stator 7, sensor 11, wireless communication circuit 12, and power supply circuit 13 can be arranged on the same circumference. With this arrangement, the stator 7, sensor 11, wireless communication circuit 12, and 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, when arranging electronic components with large mounting areas, such as the wireless communication circuit 12 including the antenna 12a and the power supply circuit 13 including a rectifier circuit, there is a limit to how narrow the radial width of the circuit board on which these components are mounted can be reduced. If the yoke 16 of the stator 7 is provided around the entire circumference as in the past, the radial width of the space required to arrange the circuit board 9 on which the sensor 11, wireless communication circuit 12, etc. are mounted cannot be secured unless the outer diameter of the sensor unit 4 is enlarged. Therefore, the stator 7 and the sensor 11, etc. cannot be arranged in the same axial position. On the other hand, if the outer diameter of the sensor unit 4 is enlarged, the annular space between the mating member 3 and the rotating member 1 must be correspondingly enlarged in the radial direction. However, when a small-sized bearing having an outer diameter of 80 mm or less is used as the bearing 2 in a standard bearing, the amount by which the annular space can be expanded in the radial direction by the stepped ends 1b, 3b of the rotating member 1 and the mating member 3 is limited, as shown in FIGS. 2 and 8 , and the radial width of the space required to arrange the sensor 11, wireless communication circuit 12, etc. cannot be secured.

[0078] In contrast, if 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 (equivalent 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 increasing the outer diameter of the sensor unit 4. For this reason, even when a standard small bearing is used as bearing 2, as described above, if the axial width of the space required to arrange sensor unit 4 and magnetic ring 6 is reduced, and the axial width of sensor unit 4 is reduced by arranging stator 7, sensor 11, wireless communication circuit 12, etc. in the same axial position without increasing the outer diameter of sensor unit 4, and the radial width of the annular space for arranging sensor unit 4 and magnetic ring 6 radially opposite each other is increased by stepped ends 1b, 3b of rotating member 1 and mating member 3, it is possible to arrange sensor unit 4 and magnetic ring 6 so that they do not protrude axially or radially from bearing 2, which is configured as a standard small bearing, then the axial width and inner and outer diameters of this bearing device can be made equivalent to the major dimensions of a standard small bearing.

[0079] This bearing device is as described above (see Figures 1, 2, and 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 stator 7 are arranged in positions that face each other radially.

[0080] In particular, this bearing device has a stator 7 that is provided with 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, which makes it possible to reduce the width of the sensor unit 4 while avoiding an increase in the diameter of the sensor unit 4, thereby reducing the space required to arrange the sensor unit 4 and magnetic ring 6.

[0081] In this manner, in this bearing device, 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 magnetic ring 6 are arranged radially opposed to each other, and the dimensions of the sensor unit 4 can be reduced, thereby reducing the space required to arrange the sensor unit 4 and the magnetic ring 6. Furthermore, even in the case of a bearing 2 configured as a standard and small bearing, it becomes easy to accommodate the sensor unit 4 and magnetic ring 6 between the rotating member 1 and the mating member 3 so that they are radially opposed to each other.

[0082] Furthermore, in this bearing device, the stator 7 has a yoke 16 and a coil 17 arranged radially opposite the magnetic ring 6, the yoke 16 having first and second claw pole portions 16 a and 16 b arranged alternately at intervals in the circumferential direction, a first side wall portion 16 c extending radially from the first claw pole portion 16 a toward the anti-magnetic ring, a second side wall portion 16 d extending radially from the second claw pole portion 16 b toward the anti-magnetic ring, and a connecting wall portion 16 e extending over a finite length in the circumferential direction between the first and second side wall portions 16 c and 16 d, and the coil 17 has a first coil portion 17 a passing circumferentially between the first and second side wall portions 16 c and 16 d, and a second coil portion 17 b passing circumferentially through a position on the anti-magnetic ring 6 side of the connecting wall portion 16 e, which is wound around the connecting wall portion 16 e. This allows the claw-pole generator 5 to be provided with a finite length in the circumferential direction.

[0083] In addition, in this bearing device, the yoke 16 is made up of a first magnetic material member 20 and a second magnetic material member 21 provided with a finite length in the circumferential direction, and the first magnetic material 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 diamagnetic 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, 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, and the sensor 11, wireless communication circuit 12, and power supply circuit 13 are housed between the annular plate portion 20c and the circumferential plate portion 20b of the first magnetic material member 20. Therefore, using only the two members, the first magnetic material member 20 and the second magnetic material member 21, the storage section 8 for housing the sensor 11 etc. and the yoke 16 can be arranged 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 axially 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] Furthermore, in this bearing device, the rotating member 1 comprises a first raceway ring, the mating member 3 comprises a second raceway ring, and the bearing 2 is a rolling bearing having rolling elements 14 arranged between the rotating member 1 and the mating member 3. The rotating member 1 and the mating member 3 have stepped end portions 1b, 3b that face each other in the radial direction, and the magnetic ring 6 is fitted into the stepped end portion 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 portion 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 end portions 1b, 3b of the rotating member 1 and the mating member 3, and therefore the sensor unit 4 and magnetic ring 6 can be accommodated within the bearing 2 without increasing 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. The following description will focus on the differences from the first embodiment.

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

[0090] The sensor unit 4 is fitted to a stepped end portion formed on the mating member 35. The magnetic ring 6 is fitted to a stepped end portion formed on the 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 when a sensor unit and magnetic ring are attached to the end of the raceway ring 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, an example was given of a bearing 2 in which the outer ring is a stationary ring and the inner ring is a rotating ring, but it is also possible to use the outer ring as a rotating ring and the inner ring as a stationary ring, attach a sensor unit to the inner ring which is a stationary ring, and attach a magnetic ring to the outer ring which is a rotating ring.

[0093] Furthermore, in the above-described embodiments, examples have been given of cases in which the magnetic ring is attached to the rotating ring or the 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 in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0095] 1, 34 Rotating member 2, 32, 33 Bearing 3, 35 Mating member 4 Sensor unit 5 Generator 6 Magnetic ring 7 Stator 11 Sensor 12 Wireless communication circuit 13 Power supply circuit 14 Rolling element 16 Yoke 16a First claw pole portion 16b Second claw pole portion 16c First side wall portion 16d Second side wall portion 16e Connecting wall portion 17 Coil 17a First coil portion 17b Second coil portion 20 First magnetic member 21 Second magnetic member 22 Arc-shaped bobbin 22a First groove portion 22b Second groove portion 22c Slit 22d Partition portion

Claims

1. A bearing device comprising a rotating member, a bearing which rotatably supports the rotating member, a mating member arranged coaxially with the rotating member, a sensor unit attached to the mating member, and a generator which converts the rotational motion of the rotating member into AC power, wherein the sensor unit houses a sensor, a wireless communication circuit which transmits the detection results of the sensor, and a power supply circuit which converts the AC power into DC power, and the generator has a magnetic ring which rotates integrally with the rotating member and a stator provided in the sensor unit, wherein the magnetic ring and the stator are disposed in positions which face each other in the radial direction, 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 disposed on the same circumference.

2. A bearing device as described in claim 1, wherein the stator has a yoke and a coil arranged in a position radially opposite the magnetic ring, the yoke has first and second claw pole portions arranged alternately at a circumferential interval, a first side wall portion extending radially from the first claw pole portion toward the anti-magnetic ring side, a second side wall portion extending radially from the second claw pole portion toward the anti-magnetic ring side, and a connecting wall portion spanning 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 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 anti-magnetic ring side of the connecting wall portion.

3. The bearing device according to claim 2, wherein the yoke is made up 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 having 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 anti-magnetic ring side of the annular side plate portion to one side in the axial direction, the second magnetic material member having 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 anti-magnetic 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 housed between the annular plate portion and the circumferential plate portion of the first magnetic material member.

4. A bearing device as described in claim 3, wherein the sensor unit has an arc-shaped bobbin axially stacked on the annular side plate portion, the arc-shaped bobbin having a first groove portion radially supporting the first coil portion, a second groove portion radially supporting the second coil portion, and a partition portion forming a slit extending axially between the first groove portion and the second groove portion, and the connecting wall portion reaching the annular side plate portion through the slit.

5. A bearing device as claimed in any one of claims 1 to 4, wherein the rotating member comprises a first raceway, the mating member comprises 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 axially from the rotating member, and the sensor unit is fitted into the stepped end of the mating member so as not to protrude axially from the mating member.

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