JP2018189128A - Bearing with sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing with a sensor which enables reduction of an entire thickness and suppresses magnetic fields of permanent magnets leaking to the outside.SOLUTION: A bearing 1 with a sensor includes a bearing body 20, power generation parts 3, a sensor 44, a communication circuit 45 and a cover 10. The cover 10 is formed by a material having magnetism and includes at least a toric top plate 12 which faces an outer ring 21 and a cylindrical side plate 11 connected to a periphery of the top plate 12 and fixed to the outer ring 21. Further, the power generation parts 3 are respectively disposed in multiple recessed parts 18 of the cover 10.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a sensor-equipped bearing.

  Patent Document 1 and Patent Document 2 describe a sensor-equipped bearing that detects various physical quantities around the bearing with a sensor and wirelessly transmits detection information to a receiving device.

JP 2003-307435 A JP 2016-130577 A

  The spacer shown in Patent Document 1 describes the use of magnetic stainless steel such as martensitic stainless steel or ferritic stainless steel as the magnetic material. However, since a permanent magnet is used for the power generation unit, if the spacer is thinned, the magnetic field of the permanent magnet may leak to the outside.

  The objective of this invention is providing the bearing with a sensor which suppresses the magnetic field of the permanent magnet which leaks outside while reducing the thickness of the whole.

  The sensor-equipped bearing according to this aspect includes a bearing main body having a relatively rotating outer ring and an inner ring, a power generation based on relative rotation between the outer ring and the inner ring, and a permanent magnet and a yoke connected to the permanent magnet. A power generation unit including a coil wound around the yoke, a sensor for detecting a physical quantity or a chemical amount by the electric power generated by the power generation unit, a magnetic material, and the power generation unit and the A cover that houses the sensor and is fixed to the bearing, and the cover is at least an annular top plate facing the outer ring, and a cylindrical shape connected to the periphery of the top plate and fixed to the outer ring. The power generation unit is disposed in the recess of the top plate.

  According to this configuration, even if there is a recess in the cover, the cover has a high magnetic permeability, so that it is possible to secure the amount of power generated by the power generation unit. For this reason, the thickness of the cover can be reduced. For this reason, the bearing with a sensor can make the whole thickness thin. Moreover, since the top plate is thicker around the power generation unit than the concave portion of the top plate, the magnetic field of the permanent magnet that leaks to the outside can be suppressed.

  As a desirable aspect, the concave portion of the top plate includes a first concave portion and a second concave portion having different depths, and the top plate has a small thickness portion, a middle thickness portion, and a large thickness portion that increase in thickness in order. A coil is disposed in the small thickness portion at a position corresponding to the first recess, and the permanent magnet is disposed in the middle thickness portion at a position corresponding to the second recess.

  According to this configuration, the coil space increases and the number of turns of the coil can be increased. Thereby, the electric power generation amount of an electric power generation part can be enlarged.

  As a desirable mode, the middle wall thickness portion is surrounded by the smaller wall thickness portion on the inner diameter side and the larger wall thickness portions on the both sides in the circumferential direction and the outer diameter side when viewed from the rotation axis direction of the bearing body. ing.

  According to this configuration, since the large thick portion thicker than the middle thick portion is disposed around the middle thick portion where the permanent magnet is disposed, the magnetic field of the permanent magnet leaking outside is further suppressed. it can.

  As a desirable mode, a tone ring having a convex portion fixed to the inner ring and projecting in the radial direction side and a concave portion recessed toward the inner diameter side than the convex portion is provided, and the circumferential width of the convex portion is It is larger than the circumferential width of the small thickness portion on the radially inner end surface, and the radially inner end surface of the large thickness portion faces the tone ring via a gap.

  According to this configuration, the magnetic flux easily flows to the large thickness portion. As a result, the magnetic field of the permanent magnet that leaks to the outside can be further suppressed.

  As a desirable mode, the inner diameter side end surface of the yoke is located on the outer diameter side of the inner peripheral surface of the inner ring.

  According to this configuration, the magnetic flux in the yoke is less likely to leak to the inner ring side even if the cover is thin.

  As a desirable mode, it further includes a communication circuit that wirelessly transmits detection information obtained by the sensor using the electric power generated by the power generation unit, and the cover houses the communication circuit.

  According to this structure, detection information can be transmitted by radio | wireless and a bearing with a sensor becomes small.

  As a desirable mode, the cover further includes an antenna on the side of the bearing body, and a nonmagnetic lid is provided on a portion of the cover facing the antenna.

  According to this configuration, even if the cover has magnetism, the electromagnetic wave of the antenna can pass through the nonmagnetic lid.

  ADVANTAGE OF THE INVENTION According to this invention, while reducing the whole thickness, the bearing with a sensor which suppresses the magnetic field of the permanent magnet which leaks outside can be provided.

FIG. 1 is a perspective view of a sensor-equipped bearing according to the present embodiment. FIG. 2 is an exploded perspective view of the sensor-equipped bearing according to the present embodiment. FIG. 3 is a partial cross-sectional view of the sensor-equipped bearing of the present embodiment. FIG. 4 is a partial cross-sectional view of the sensor-equipped bearing according to the present embodiment. FIG. 5 is an explanatory diagram for explaining the relationship between the voltage of electromotive force and time in the sensor-equipped bearing of the present embodiment. FIG. 6 is a plan view of the sensor unit of the present embodiment. FIG. 7 is a perspective view of the cover of the present embodiment. FIG. 8 is a partial cross-sectional view of the yoke and magnet of this embodiment. FIG. 9 is a partially cutaway perspective sectional view of the yoke and magnet of this embodiment. FIG. 10 is a schematic diagram for explaining a state of magnetic flux in the yoke, the convex or concave portion of the tone ring, and the cover according to the present embodiment. FIG. 11 is a partial cross-sectional view of a sensor-equipped bearing according to a comparative example.

  EMBODIMENT OF THE INVENTION About the form (embodiment) for inventing, it demonstrates in detail, referring drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.

  FIG. 1 is a perspective view of a sensor-equipped bearing according to the present embodiment. FIG. 2 is an exploded perspective view of the sensor-equipped bearing according to the present embodiment. FIG. 3 is a partial cross-sectional view of the sensor-equipped bearing of the present embodiment. FIG. 4 is a partial cross-sectional view of the sensor-equipped bearing according to the present embodiment. The sensor-equipped bearing 1 shown in FIG. 1 includes a sensor unit 5, a tone ring 30, and a bearing body 20, as shown in FIG.

  As shown in FIGS. 3 and 4, the bearing body 20 is a rolling bearing having an outer ring 21, an inner ring 22, and rolling elements 23. Hereinafter, although the inner ring 22 will be described as a rotating wheel, any of the inner ring 22 and the outer ring 21 may be rotated as long as the inner ring 22 and the outer ring 21 are relatively rotated.

  The cover 10 includes an annular top plate 12 and a cylindrical side plate 11 connected to the periphery of the top plate 12. The cover 10 is formed of a magnetic material such as silicon steel plate, carbon steel (JIS standard SS400 or S45C), martensitic stainless steel (JIS standard SUS420), or ferritic stainless steel (JIS standard SUS430).

  As shown in FIG. 2, in the sensor unit 5, a plurality of power generation units 3 and sensor units 40 are attached to the bearing body 20 side facing surface of the top plate 12. The sensor unit 40 includes a power supply substrate 41 and a sensor substrate 42.

  For example, as shown in FIGS. 1 and 2, the power generation unit 3 is fixed to the top plate 12 by fastening a bolt 19 made of a nonmagnetic material such as brass into a female screw hole formed in the top plate 12. Similarly, a bolt 47 made of a nonmagnetic material such as brass is fastened to a female screw hole formed in the top plate 12, whereby the power supply substrate 41 and the sensor substrate 42 are fixed to the top plate 12. As shown in FIG. 1, the bolt 19 and the bolt 47 have a length that does not protrude from the top plate 12 when attached to the cover 10.

  The tone ring 30 is provided with convex portions 31 protruding toward the outer diameter side and concave portions 32 recessed toward the inner diameter side of the convex portion 31 alternately in the circumferential direction. The tone ring 30 has a cylindrical projection 33 protruding toward the bearing body 20 on the inner peripheral side.

  The tone ring 30 is formed of a magnetic material such as silicon steel plate, carbon steel (JIS standard SS400 or S45C), martensitic stainless steel (JIS standard SUS420), or ferritic stainless steel (JIS standard SUS430). .

  The power generation unit 3 includes a permanent magnet 13, a yoke 14, and a coil 15. The permanent magnet 13 is fixed so as to contact the top plate 12. Since the permanent magnet 13 is not fixed to the bearing body 20 but is attached to the cover 10, the safety is excellent.

  The yoke 14 is fixed so as to contact the permanent magnet 13. The yoke 14 may be magnetically connected to the permanent magnet 13 and may not be directly connected. The yoke 14 is made of a magnetic material such as a silicon steel plate or a NiFe alloy. The yoke 14 is desirably made of a material having a permeability equal to or higher than that of the cover 10 so that the amount of magnetic flux inside the yoke 14 is increased. When the yoke 14 is a silicon steel plate, the magnetic permeability increases, and the magnetic flux easily passes through the yoke 14.

  The coil 15 is a so-called magnet wire in which a conducting wire is wound around the yoke 14. It is desirable to wind as many conductive wires as possible with a thin wire diameter so that the amount of power generation increases. The coils 15 of the adjacent power generation units 3 are connected in series, and wirings drawn from the coils 15 of the plurality of power generation units 3 connected in series are connected to the power supply substrate 41.

  As shown in FIG. 3, one end of the side plate 11 is fitted and fixed in a groove 21 </ b> A provided on the outer periphery of the outer ring 21. The cylindrical protrusion 33 is fitted and fixed in a groove 22 </ b> A provided on the inner periphery of the inner ring 22. Thereby, as shown in FIGS. 3 and 4, the inner peripheral side end surface of the yoke 14 and the inner peripheral side end surface of the top plate 12 are arranged at positions facing the convex portion 31 or the concave portion 32 of the tone ring 30. The cover 10 and the tone ring 30 can be easily attached to the bearing body 20.

  The magnetic flux Mf passes through the yoke 14, the convex portion 31 or the concave portion 32 of the tone ring 30, and the top plate 12 of the cover 10 by the magnetic field of the permanent magnet 13. For this reason, the permanent magnet 13, the yoke 14, the convex portion 31 or the concave portion 32 of the tone ring 30, and the top plate 12 of the cover 10 constitute a magnetic circuit.

  FIG. 5 is an explanatory diagram for explaining the relationship between the voltage of electromotive force and time in the sensor-equipped bearing of the present embodiment. Here, the horizontal axis of FIG. 5 is the time T, and the vertical axis is the voltage Vi of the electromotive force. When the outer ring 21 is fixed and the inner ring 22 rotates, the tone ring 30 rotates together with the inner ring 22, and the tone ring 30 and the power generation unit 3 rotate relatively. For the yoke 14, an air gap from the inner peripheral side end surface to the outer peripheral side end surface 31IF of the convex portion 31 shown in FIG. 3, an air gap from the inner peripheral side end surface to the outer peripheral side end surface 32IF of the concave portion 32 shown in FIG. Alternate.

  As described above, the distance between the yoke 14 of the power generation unit 3 and the outer periphery of the tone ring 30 is periodically changed by the convex portion 31 and the concave portion 32 on the outer periphery of the tone ring 30. As a result, the density of the magnetic flux Mf generated in the power generation unit 3 changes. When the yoke 14 provided with the permanent magnet 13 and the tone ring 30 are close to each other, the magnetic flux passing through the permanent magnet 13, the yoke 14 and the tone ring 30 is large, and the yoke 14 and the tone ring 30 are separated from each other. Therefore, the magnetic flux passing through the permanent magnet 13, the yoke 14, and the tone ring 30 is reduced. In accordance with the density change of the magnetic flux Mf, a voltage change occurs in the coil 15 in which a magnet wire is wound around the yoke 14.

  That is, when the yoke 14 and the outer peripheral side end face 31IF of the convex portion 31 are closest, the magnetic flux Mf shown in FIG. 3 increases and the electromotive force voltage V1 shown in FIG. When the yoke 14 and the outer peripheral side end face 32IF of the recess 32 are farthest away, the magnetic flux Mf shown in FIG. 4 is reduced, and the electromotive force voltage V2 shown in FIG.

  FIG. 6 is a plan view of the sensor unit of the present embodiment. As shown in FIG. 6, a power supply unit 43 is mounted on the power supply board 41. The power supply unit 43 includes, for example, a rectifier circuit, a smoothing circuit, a protection circuit, and a power supply circuit. The power supply unit 43 converts the single-phase AC power supplied from the power generation unit 3 into a DC voltage and supplies the DC voltage to the sensor substrate 42.

  The sensor substrate 42 includes a sensor 44, a communication circuit 45, and an antenna 46. DC power from the power supply unit 43 is at least supplied to the sensor 44 and the communication circuit 45.

  The sensor 44 senses various physical quantities or chemical quantities using the supplied DC power. For example, the sensor 44 is a temperature sensor that detects the ambient temperature of the bearing body 20, a vibration sensor that detects vibration of the bearing body 20, a humidity sensor that detects ambient humidity of the bearing body 20, and an oxidative deterioration of the lubricating oil of the bearing body 20. Among various detection units such as a gas sensor for detecting gaseous hydrocarbons, hydrogen sulfide, ammonia and the like generated along with the above, an ultrasonic sensor for detecting frictional noise generated in the bearing body 20, and a rotation sensor for detecting the rotation of the bearing body 20 Any one or a plurality of detection units.

  The communication circuit 45 is a device including a CPU (Central Processing Unit) and a wireless transmission / reception circuit. A microcomputer is included in the apparatus. The communication circuit 45 wirelessly transmits the detection information sensed by the sensor 44 to the communication unit 51 using DC power supplied from the power supply unit 43. The detection information detected by the sensor 44 is processed by the communication circuit 45, transmitted via the antenna 46 by radio communication of the electromagnetic wave WV shown in FIG. 1, and received by the communication unit 51 of the host device 50, for example. Detection information received by the communication unit 51 is processed by the computer 52. By providing the communication circuit 45, the detection information can be transmitted wirelessly, and the sensor-equipped bearing 1 becomes small. Note that the communication circuit 45 may perform wired communication with the communication unit 51.

  FIG. 7 is a perspective view of the cover of the present embodiment. As shown in FIG. 7, the cover 10 has a through hole 12H. As shown in FIG. 1, the through hole 12H is sealed with a nonmagnetic lid 17 formed of a nonmagnetic material such as resin.

  As described above, the cover 10 includes the antenna 46 on the bearing body 20 side. Here, since the cover 10 has magnetism, it has an action of shielding electromagnetic waves from the antenna 46. For this reason, as shown in FIG. 6, the antenna 46 is disposed so as to overlap the nonmagnetic lid 17 in a plan view of the bearing body 20 as viewed from the direction of the rotation axis Zr. That is, the nonmagnetic lid 17 is provided on the portion of the cover 10 that faces the antenna 46. For this reason, the electromagnetic wave WV of the antenna 46 can reach the communication unit 51 via the nonmagnetic lid 17.

  As shown in FIGS. 3 and 6, each power generation unit 3 includes a permanent magnet 13. The magnetic field of the permanent magnet 13 may affect the operation of the sensor unit 40. A plurality of power generation units 3 are arranged on one side and a sensor unit 40 is arranged on the other side with an arbitrary virtual line IM passing through the rotation axis Zr as seen from the direction of the rotation axis Zr of the bearing body 20. For this reason, the influence of the permanent magnet 13 of the power generation unit 3 on the sensor unit 40 is reduced. And the some electric power generation part 3 is arranged in the circumferential direction, and is arrange | positioned so that the surface density of the electric power generation part 3 may become high. Since the plurality of power generation units 3 are arranged in the circumferential direction instead of the rotation axis Zr direction of the bearing body 20 described later, the thickness of the cover 10 can be reduced.

  As shown in FIG. 3, in the sensor-equipped bearing 1 of the present embodiment, it is desired that the protrusion thickness D1 from the bearing body 20 is small. When the protrusion thickness D1 from the bearing body 20 is reduced, the accommodation space in the cover 10 is reduced. For example, in the cover 10, the distance D <b> 2 from the bearing body 20 (outer ring 21) to the top plate 12 decreases as the protrusion thickness D <b> 1 from the bearing body 20 decreases. In the tone ring 30, the protrusion thickness D <b> 3 from the bearing body 20 is equal to or less than the protrusion thickness D <b> 1 from the bearing body 20, and at least the inner peripheral side end surface of the top plate 12 is the convex portion 31 or the concave portion 32 of the tone ring 30. It is more than the position facing. The protrusion thickness D3 from the bearing body 20 is such that if the inner peripheral side end surface of the top plate 12 is not located at a position facing the convex portion 31 or the concave portion 32 of the tone ring 30, the gap becomes large and the magnetic flux Mf may decrease. There is sex.

  Since the power generation unit 3 cannot contact the bearing body 20, it is conceivable to reduce the thickness of the top plate 12. When the thickness of the top plate 12 is reduced, the protrusion thickness D1 from the bearing body 20 is also reduced. However, since the permanent magnet 13 is in contact with the top plate 12, if the thickness of the top plate 12 is reduced, the magnetic field of the permanent magnet 13 leaks to the outside of the top plate 12, and external iron powder or the like may be adsorbed. There is sex.

  Therefore, as shown in FIG. 7, a recess 18 whose thickness is partially recessed is formed on the bearing side surface of the top plate 12. The power generation unit 3 is disposed at the position of the recess 18.

  FIG. 8 is a partial cross-sectional view of the yoke and magnet of this embodiment. FIG. 9 is a partially cutaway perspective sectional view of the yoke and magnet of this embodiment. As shown in FIGS. 7, 8 and 9, the recess 18 includes a first recess 18A and a second recess 18B having different depths. The first recess 18A is deeper than the second recess 18B with respect to the reference surface 18C of the top plate 12.

  The top 12 is composed of a small thickness portion 121, a middle thickness portion 122, and a large thickness portion 123 by the first recess 18A and the second recess 18B. And thickness becomes large in order of the small thickness part 121, the middle thickness part 122, and the large thickness part 123. FIG. The small thickness portion 121 is located on the inner diameter side with respect to the middle thickness portion 122. As shown in FIG. 8, the surfaces of the small-thickness portion 121, the middle-thickness portion 122, and the large-thickness portion 123 opposite to the outer ring 21 are flush with each other.

  The depth of the second recess 18B with respect to the reference surface 18C of the top plate 12 is smaller than the thickness of the permanent magnet 13 in the direction of the rotation axis Zr. Thereby, contact with the large thickness part 123 and the yoke 14 is suppressed.

  The permanent magnet 13 is arranged in contact with the middle thickness portion 122 in the second recess 18B. Since there is a step between the small-thickness portion 121 and the middle-thickness portion 122, the space of the coil 15 is increased, and the number of turns of the coil 15 can be increased.

  As shown in FIGS. 7 and 9, the small-thickness portion 121 is opposed to the tone ring 30 on the radially inner side through a gap. The small thickness portion 121 is sandwiched between the large thickness portions 123 on both sides in the circumferential direction, and an intermediate thickness portion 122 is provided on the radially outer side of the small thickness portion 121.

  As shown in FIG.7 and FIG.9, the middle thickness part 122 is pinched | interposed into the large thickness part 123 in the circumferential direction both sides. Further, the middle thickness portion 122 is sandwiched between a small thickness portion 121 on the radially inner side and a large thickness portion 123 on the outer diameter side.

  FIG. 10 is a schematic diagram for explaining a state of magnetic flux in the yoke, the convex or concave portion of the tone ring, and the cover according to the present embodiment. As shown in FIG. 10, since there are large thickness portions 123 in three directions around the middle thickness portion 122, the magnetic flux Mfs flows to the large thickness portion 123 in addition to the magnetic flux Mf of the permanent magnet 13. For this reason, the leakage magnetic field which the magnetic field of the permanent magnet 13 leaks to the outer side of the top plate 12 is suppressed. Thereby, the bearing 1 with a sensor of this embodiment can make distance D2 from the bearing main body 20 (outer ring | wheel 21) and the top plate 12 small, and can reduce the protrusion thickness D1 from the bearing main body 20. FIG.

  As shown in FIG. 6, the plurality of power generation units 3 are arranged and arranged in the circumferential direction, and there is a large thickness portion 123 between the plurality of power generation units 3. The radially inner end surface 123E of the large thickness portion 123 faces the tone ring 30 in the radial direction. For this reason, the radially inner end surface 123E of the large thickness portion 1231 is opposed to the tone ring 30 on the radially inner side via a gap. Further, the circumferential width W3 of the convex portion 31 or the concave portion 32 of the tone ring 30 is larger than the circumferential width W1 of the small thickness portion 121 on the radially inner end face of the cover 10. As a result, the magnetic flux Mfs is likely to flow to the large thickness portion 123. As a result, the leakage magnetic field in which the magnetic field of the permanent magnet 13 leaks outside the top plate 12 is further suppressed.

  FIG. 11 is a partial cross-sectional view of a sensor-equipped bearing according to a comparative example. The same components as those in this embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In the sensor-equipped bearing 1 </ b> A of the comparative example, the outer diameter of the convex portion 31 of the tone ring 30 is smaller than the outer diameter of the inner ring 22. Naturally, the outer diameter of the recess 32 of the tone ring 30 is also smaller than the outer diameter of the inner ring 22. In such a structure, as described above, when the distance from the bearing body 20 (outer ring 21) to the top plate 12 is reduced, the yoke 14 approaches the inner ring 22. In the comparative example, there is an inner ring 22 in the direction of the rotation axis Zr of the yoke 14, and a leakage magnetic flux Mfl is generated in which the magnetic flux in the yoke 14 leaks to the inner ring 22 side, and the power generation amount of the power generation unit 3 is reduced.

  On the other hand, as shown in FIG. 3, there is a distance H1 between the inner diameter side end surface of the yoke 14 and the inner peripheral surface 22IF of the inner ring 22. Therefore, in the sensor-equipped bearing 1 of the present embodiment, as shown in FIG. 3, the inner diameter side end surface of the yoke 14 is on the outer diameter side with respect to the inner peripheral surface 22 IF of the inner ring 22. According to such a structure, even if the distance D2 from the bearing body 20 (outer ring 21) to the top plate 12 is reduced, the leakage magnetic flux Mfl in which the magnetic flux in the yoke 14 leaks to the inner ring 22 side as shown in FIG. Can be suppressed.

  As described above, the sensor-equipped bearing 1 according to the present embodiment includes the bearing body 20, the power generation unit 3, the sensor 44, and the cover 10. The bearing body 20 has an outer ring 21 and an inner ring 22 that rotate relatively. The power generation unit 3 includes a permanent magnet 13, a yoke 14 that is magnetically connected to the permanent magnet 13, and a coil 15 that is wound around the yoke 14. The power generation unit 3 generates power based on the relative rotation between the outer ring 21 and the inner ring 22. The sensor 44 detects a physical quantity or a chemical quantity using the electric power generated by the power generation unit 3.

  The cover 10 includes at least an annular top plate 12 facing the outer ring 21, and a cylindrical side plate 11 connected to the periphery of the top plate 12 and fixed to the outer ring 21. In addition, the power generation units 3 are respectively disposed in the plurality of recesses 18 of the cover 10.

  With this structure, the distance D2 from the bearing body 20 (outer ring 21) to the top plate 12 is reduced, and the protrusion thickness D1 of the cover 10 from the bearing body 20 is reduced. Since the top plate 12 is thicker around the power generation unit 3 than the concave portion 18 of the top plate 12, the magnetic field of the permanent magnet 13 that leaks to the outside can be suppressed.

  Here, the middle thickness portion 122 is surrounded by a small thickness portion 121 on the inner diameter side and three large thickness portions 123 on both sides in the circumferential direction and on the outer diameter side when viewed from the rotation axis Zr direction of the bearing body 20. ing.

  According to this structure, since the large thick portion 123 thicker than the middle thick portion 122 is disposed around the middle thick portion 122 where the permanent magnet 13 is disposed, the permanent magnet 13 leaking outside. The magnetic field can be further suppressed.

  The cover 10 is made of a magnetic material. According to this structure, even if there is the concave portion 18 of the cover 10, since the magnetic permeability of the cover 10 is high, the power generation amount of the power generation unit 3 can be ensured.

DESCRIPTION OF SYMBOLS 1, 1A Bearing with sensor 3 Power generation part 5 Sensor unit 10 Cover 11 Side plate 12 Top plate 13 Permanent magnet 14 Yoke 15 Coil 17 Nonmagnetic lid 18 Recess 18A First recess 18B Second recess 18C Reference surface 20 Bearing body 21 Outer ring 21A, 22A Groove 22 Inner ring 23 Rolling element 30 Tone ring 31 Convex part 32 Concave part 33 Tubular protrusion 40 Sensor part 41 Power supply board 42 Sensor board 43 Power supply part 44 Sensor 45 Communication circuit 46 Antenna 50 Host device 51 Communication part 52 Computer 121 Small thickness Part 122 Medium thickness part 123 Large thickness part

Claims (7)

A bearing body having a relatively rotating outer ring and inner ring;
A power generation unit that generates electric power based on relative rotation between the outer ring and the inner ring, and includes a permanent magnet, a yoke connected to the permanent magnet, and a coil wound around the yoke;
A sensor for detecting a physical quantity or a chemical quantity by the electric power generated by the power generation unit;
A cover formed of a material having magnetism and containing the power generation unit and the sensor and fixed to the bearing,
The cover includes at least an annular top plate facing the outer ring, and a cylindrical side plate connected to the periphery of the top plate and fixed to the outer ring,
A sensor-equipped bearing in which the power generation unit is disposed in a recess of the top plate. The recess of the top plate includes a first recess and a second recess having different depths,
The top plate has a small thickness portion, a middle thickness portion, and a large thickness portion that increase in thickness in order, and a coil is disposed in the small thickness portion at a position corresponding to the first recess, The sensor-equipped bearing according to claim 1, wherein the permanent magnet is disposed in the middle thick portion at a position corresponding to the second recess.   The middle thickness portion is surrounded by the small thickness portion on the inner diameter side and the large thickness portions on both sides in the circumferential direction and on the outer diameter side when viewed from the rotation axis direction of the bearing body. The sensor-equipped bearing according to 2. A tone ring that includes a convex portion that is fixed to the inner ring and protrudes in the radial direction, and a concave portion that is recessed toward the inner diameter side of the convex portion,
The circumferential width of the convex portion is larger than the circumferential width of the small thickness portion on the radially inner end surface of the cover,
4. The sensor-equipped bearing according to claim 2, wherein a radially inner end surface of the large thickness portion faces the tone ring via a gap.   5. The sensor-equipped bearing according to claim 1, wherein an inner diameter side end surface of the yoke is located on an outer diameter side with respect to an inner peripheral surface of the inner ring. Furthermore, a communication circuit that wirelessly transmits detection information obtained by the sensor, using the power generated by the power generation unit,
The sensor-equipped bearing according to claim 1, wherein the cover accommodates the communication circuit. Further, the cover includes an antenna on the bearing body side,
The sensor-equipped bearing according to claim 6, wherein a portion of the cover facing the antenna is provided with a nonmagnetic lid.

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