Bearing device

Abstract

To provide a bearing device capable of accurately detecting a temperature change of a bearing ring of a rolling bearing.SOLUTION: A first bearing ring 4 has an inner periphery including a raceway surface part 15, a step part 18 for receiving an annular side part 11 of a holder 9 of a sensor unit 2 in an axial direction, and a peripheral face part 19 fitted to a fitting part 12 of the holder 9. The step part 18 receives a side face 21 on the rolling element 6 side of the annular side part 11 in the axial direction at a position opposed to the raceway surface part 15 in the axial direction. A circuit board 8 is arranged on a side face 22 on the counter rolling element 6 side of the annular side part 11. A heat conduction path 28 is provided which ranges from the raceway surface part 15 to a temperature sensor 10 of the circuit board 8 in the axial direction and includes the step part 18 and the annular side part 11.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, a bearing device has been known in which sensors for detecting the condition of a rolling bearing are mounted on a substrate to form a circuit board, the circuit board is held in a holder and assembled into a sensor unit, and the sensor unit is fixed to a raceway ring.

[0003] For example, in the bearing device of Patent Document 1, a holder with an L-shaped cross section is attached to the raceway. The holder has an annular side portion extending in the radial direction and a fitting portion protruding in the axial direction from the raceway side of the annular side portion. The holder also serves as a yoke in the stator of the generator. The fitting portion of the holder is fitted to the circumferential surface portion of the raceway, and the protruding end face of the fitting portion is abutted against the step portion of the raceway in the axial direction. The circuit board is a control board including a plurality of sensors such as a temperature sensor. This circuit board is fixed on the side surface of the annular side portion on the rolling element side. The circumferential surface portion and the step portion of the raceway are formed between an end face located at one end that defines the width of the raceway and the raceway surface portion, and the sensor unit is arranged so as not to protrude from the raceway in the axial direction. The rolling bearing generates heat as the rolling bearing rotates. This heat occurs at the contact portion between the raceway surface portion and the rolling element. When the temperature sensor detects the temperature change based on the heat, it can be used as information indicating the condition of the bearing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-307435 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the bearing device of Patent Document 1, the circuit board containing the temperature sensor is located far away from the raceway surface of the raceway ring, which raises concerns that there will be a large delay in detecting the above-mentioned heat generated in the raceway surface, and that accurate temperature measurement will become difficult.

[0006] In view of the above background, an object of the present invention is to provide a bearing device capable of quickly and accurately detecting a temperature change in the raceway of a rolling bearing. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention adopts a configuration 1 of a bearing device comprising: a rolling bearing having a first raceway, a second raceway, and a plurality of rolling elements arranged between the first raceway and the second raceway; a sensor unit having a circuit board and a holder for holding the circuit board, wherein the circuit board has a temperature sensor, the holder has an annular side portion extending radially and a fitting portion protruding in the axial direction from the annular side portion, and the first raceway has an inner or outer circumference including a raceway surface portion, a step portion for axially receiving the holder, and a peripheral surface portion that fits with the fitting portion, wherein the step portion of the first raceway axially receives a side surface of the annular side portion facing the rolling elements at a position axially opposite to the raceway surface portion, the circuit board is arranged on a side surface of the annular side portion facing the reversing moving body, and a heat conduction path is provided that continues axially from the raceway surface portion to the circuit board and includes the step portion and the annular side portion.

[0008] According to the above-mentioned configuration 1, the step of the first raceway ring axially receives the rolling element side surface of the annular side portion at a position axially opposite to the raceway surface portion, and the circuit board is disposed on the reverse moving body side surface of the annular side portion of the holder, so that the annular side portion and the circuit board can be disposed close to the raceway surface portion. If a heat conduction path is provided that is continuous in the axial direction from the raceway surface portion to the circuit board and includes the step and the annular side portion, the heat generated at the contact portion between the raceway surface portion and the rolling element can be quickly conveyed to the circuit board by the heat conduction of the path that connects the raceway surface portion and the circuit board in a straight line in the axial direction. This makes it possible to quickly and accurately detect temperature changes of the raceway ring.

[0009] In the above configuration 1, the temperature sensor is disposed at a position facing the raceway surface portion in the axial direction, and the heat conduction path is continuous from the raceway surface portion to the temperature sensor in the axial direction. According to this configuration 2, the heat conduction path between the raceway surface portion and the temperature sensor can be made short.

[0010] In the above configuration 1 or 2, a configuration 3 can be adopted in which the side surface of the annular side portion facing the inverting moving body and the circuit board are in contact with each other on the path of the heat conduction path. According to this configuration 3, the annular side portion and the circuit board are in contact with each other with no distance between them, which is advantageous in shortening the heat conduction path.

[0011] In any one of the above configurations 1 to 3, a configuration 4 can be adopted in which the side surface of the annular side portion facing the rolling element and the step portion of the first raceway are in contact with each other on the path of the heat conduction path. According to this configuration 4, the annular side portion and the step portion are in contact with each other with no distance between them, which is advantageous in shortening the heat conduction path.

[0012] In any one of the above configurations 1 to 4, a configuration 5 can be adopted in which the annular side portion of the holder is formed of a metal plate. This configuration 5 allows the annular side portion to have better thermal conductivity than a resin-made portion, and is advantageous in reducing the thickness of the annular side portion in the axial direction to shorten the heat conduction path. Effect of the Invention

[0013] As described above, by employing the above configuration 1, the present invention can provide a bearing device that is capable of quickly and accurately detecting temperature changes in the raceways of a rolling bearing. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a vertical sectional front view showing a main portion of a bearing device according to a first embodiment of the present invention; [Diagram 2] An enlarged view of the sensor unit and its surroundings in Figure 1. [Diagram 3] FIG. 2 is a perspective view showing the bearing device of FIG. [Figure 4] FIG. 2 is a side view showing the bearing device of FIG. 1 with a cover partially cut away; [Diagram 5] FIG. 2 is an exploded perspective view of the sensor unit of FIG. 1; [Figure 6] FIG. 2 is a perspective view showing an assembly stage of the sensor unit of FIG. 1; [Figure 7] FIG. 11 is a longitudinal sectional front view showing a main portion of a bearing device according to a second embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 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 6. FIG.

[0016] As shown in FIGS. 1 to 3, the bearing device includes a rolling bearing 1, a sensor unit 2, and a generator 3. The rolling bearing 1 has a cylindrical shape and a cylindrical surface.

[0017] Here, the circumferential direction centered on the central axis of the rolling bearing 1 (not shown) is referred to as the "circumferential direction," the direction along the central axis of the bearing is referred to as the "axial direction," and the direction perpendicular to the central axis of the bearing is referred to as the "radial direction." In Figures 1 and 2, the axial direction corresponds to the left-right direction, and the radial direction corresponds to the up-down direction.

[0018] 1, the rolling bearing 1 has a first raceway 4, a second raceway 5, and a plurality of rolling elements 6 arranged between the first raceway 4 and the second raceway 5. These rolling elements 6 are held at equal intervals in the circumferential direction by a cage 7.

[0019] The sensor unit 2 is a unit in which a circuit board 8 and a holder 9 for holding the circuit board 8 are integrated together.

[0020] The circuit board 8 has a temperature sensor 10 .

[0021] The holder 9 has an annular side portion 11 extending in the radial direction and a fitting portion 12 protruding from the annular side portion 11 in the axial direction.

[0022] The generator 3 consists of a magnetic ring 13 arranged so as to be rotatable integrally with the second raceway 5, and a stator 14 facing the magnetic ring 13, and the relative rotational motion between the first raceway 4 and the second raceway 5 is electromagnetically converted into alternating current by the magnetic ring 13 and the stator 14.

[0023] The rolling bearing 1 is a radial bearing. The rolling bearing 1 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 standard or the JIS standard. For example, the dimensions of radial bearings other than tapered roller bearings are specified in ISO15 or JIS B 1512-1.

[0024] Although the rolling bearing 1 is configured as a deep groove ball bearing in the above example, the rolling bearing 1 is not limited to a deep groove ball bearing.

[0025] The sensor unit 2 is fixed to the first bearing ring 4 .

[0026] The first bearing ring 4 is usually arranged as a stationary ring, and the second bearing ring 5 is usually arranged as a rotating ring.

[0027] The first raceway 4 is an outer ring having an inner circumference 16 including a first raceway surface portion 15. The second raceway 5 is an inner ring having an outer circumference including a second raceway surface portion 17. Each rolling element 6 is a ball that rolls between the raceway surface portions 15, 17. The raceway surface portions 15, 17 are the surfaces of the raceways 4, 5 that form the rolling path of the rolling elements 6, and in the illustrated example, are continuous around the entire circumferential direction with a cross-sectional shape that forms a raceway groove corresponding to the ball diameter of the rolling elements 6.

[0028] A predetermined distance is ensured between the rolling elements 6, the cage 7, and the sensor unit 2. This distance is set so that the sensor unit 2 will not come into contact with the rolling elements 6 and the cage 7 even if there is axial displacement due to the internal bearing gap of the rolling bearing 1. The cage 7 is a crown-shaped cage that has a ring portion only on the side opposite the sensor unit 2 (the side going away from the sensor unit 2, the left side in Figure 1) with respect to each rolling element 6. To avoid interference between the sensor unit 2 and the cage 7, the cage 7 has no portion that is closer to the sensor unit 2 than the rolling elements 6. The sensor unit 2 has no portion that protrudes from the rolling bearing 1 in the axial direction.

[0029] The inner circumference 16 of the first race 4 includes a step portion 18 that axially receives the annular side portion 11 of the holder 9, and a peripheral surface portion 19 that fits with the fitting portion 12 of the holder 9. The step portion 18 extends radially all around the circumference. The step portion 18 and the peripheral surface portion 19 each have a cylindrical surface that extends in the circumferential direction.

[0030] 1 and 2, the first raceway ring 4 has a width surface portion 20 located at one end of the axial width of the first raceway ring 4 (the right end in FIGS. 1 and 2). The width surface portion 20 is aligned along the radial direction. The step portion 18 and the peripheral surface portion 19 are formed at a position closer to the first raceway surface portion 15 in the axial direction than the width surface portion 20 is.

[0031] 2, a region intersecting with a virtual plane obtained by projecting the raceway surface portion 15 vertically in the axial direction is defined as a virtual projection region A. The step portion 18 is formed across the entire radial width of the virtual projection region A.

[0032] The peripheral surface portion 19 intersects with the step portion 18 at the other axial end of the peripheral surface portion 19 (the left end in Figs. 1 and 2).

[0033] In addition, the inner circumference 16 of the first raceway 4 may include at least one of a recessed portion between the step portion 18 and the circumferential surface portion 19 to facilitate processing, and a chamfered portion that removes the corners between the circumferential surface portion 19 and the width surface portion 20.

[0034] The holder 9 is an annular body that, when attached to the first bearing ring 4 , determines a predetermined position of the circuit board 8 relative to the first bearing ring 4 .

[0035] The entire holder 9 is formed from a single metal plate, and has a seamless, integral annular side portion 11 and a fitting portion 12. The entire holder 9 is formed by press working.

[0036] The annular side portion 11 is in the shape of an annular plate having both side surfaces 21, 22 extending along the radial direction over the entire circumference in the circumferential direction. The fitting portion 12 extends along the axial direction from the end portion of the annular side portion 11 that is closer to the first race 4.

[0037] The fitting portion 12 is fitted to a peripheral surface portion 19 of the first bearing ring 4. As a result, the holder 9 is disposed coaxially with the first bearing ring 4.

[0038] A side surface 21 of the annular side portion 11 on the rolling element 6 side (the side closer to the rolling element 6, the left side in FIG. 2) is butted against the step portion 18 of the first raceway 4 in the axial direction. This brings the side surface 21 of the annular side portion 11 on the rolling element 6 side into axial contact with the step portion 18. The step portion 18 properly determines the axial positional relationship between the fitted sensor unit 2 and the first raceway 4, and also restricts the sensor unit 2 from falling in the radial direction.

[0039] A side surface 22 of the annular side portion 11 on the reversible moving body 6 side (the side farther from the rolling body 6, the right side in FIG. 2) serves as a surface portion that supports the circuit board 8 in the axial direction.

[0040] As shown in Figures 2, 4 and 5, the circuit board 8 is a printed circuit board including a substrate 23, a temperature sensor 10 mounted on the substrate 23, a wireless communication circuit 24 mounted on the substrate 23, a power supply circuit 25 mounted on the substrate 23, and one or more other sensors 26 mounted on the substrate 23.

[0041] The substrate 23 is made of a printed wiring board. The substrate 23 is in the shape of an arc plate that is short in the radial direction and long in the circumferential direction. The temperature sensor 10, the wireless communication circuit 24, the power supply circuit 25, and one or more other sensors 26 are mounted on the substrate surface on the side of the reversible moving body 6 of the substrate 23 (the right side in FIG. 2).

[0042] As shown in Fig. 2, the substrate 23 is disposed at a position facing the first raceway surface portion 15 in the axial direction. That is, the substrate 23 is disposed so as to have a portion located in the imaginary projection area A. The substrate 23 is fixed to the annular side portion 11 by a plurality of screws 27, as shown in Figs. 4 and 5. As a result, the substrate surface on the rolling element 6 side (the left side in Fig. 2) of the substrate 23 is fastened in the axial direction to the side surface 22 on the reversing element 6 side of the annular side portion 11, and is brought into contact with the side surface 22 without any gaps in the portion located in the imaginary projection area A.

[0043] The temperature sensor 10 is composed of a circuit that converts temperature into an electric signal. The temperature sensor 10 is disposed in a position facing the first raceway surface portion 15 in the axial direction. In other words, the temperature sensor 10 is disposed in the imaginary projection area A. The entire temperature sensor 10 is disposed in a position facing the fitting portion 12 of the holder 9 and the peripheral surface portion 19 of the first raceway ring 4 in the radial direction.

[0044] A heat conduction path 28 (schematically shown by an arrow in Figs. 1 and 2) is provided that continues in the axial direction from the first raceway surface portion 15 to the temperature sensor 10. The heat conduction path 28 is made of a solid portion that continues in the axial direction without a gap from the first raceway surface portion 15 to at least the circuit board 8, and preferably to the temperature sensor 10, in the imaginary projection area A. In the illustrated example, the heat conduction path 28 is made up of a solid portion that continues from the first raceway surface portion 15 of the first raceway ring 4 to the step portion 18, the annular side portion 11 of the holder 9, and the substrate 23 of the circuit board 8, and therefore continues in the axial direction to the temperature sensor 10.

[0045] The rolling bearing 1 generates heat as the rolling bearing 1 rotates. One of the main causes of this heat generation is heat generated at the contact portion between the rolling element 6 and the first raceway ring 4. This heat is transferred from the first raceway surface portion 15 through the heat conduction path 28 to the temperature sensor 10 by the phenomenon of thermal conduction. Therefore, the temperature sensor 10 can detect the temperature change of the first raceway ring 4. Since the path length of the heat conduction path 28 is short in the axial direction, the above-mentioned heat reaches the temperature sensor 10 more quickly than when a space is formed between the step portion 18 of the first raceway ring 4 and the circuit board 8, or between the step portion 18 and the temperature sensor 10, so that the temperature change of the first raceway ring 4 can be detected quickly and accurately.

[0046] The technical significance of arranging the temperature sensor 10 in the virtual projection area A is to shorten the path of heat conduction in the axial direction between the first track surface portion 15 and the temperature sensor 10 for the purpose of improving the delay and accuracy of temperature detection. Therefore, while it is of course preferable to arrange the entire temperature sensor 10 in the virtual projection area A, it is considered effective to achieve the above-mentioned purpose by arranging at least the temperature sensing portion (circuit portion that converts temperature into an analog electrical signal) of the temperature sensor 10 in the virtual projection area A, and it is not essential that parts other than the temperature sensing portion, for example, the soldered portion between the temperature sensor 10 and the board 23, be located in the virtual projection area A.

[0047] Alternatively, a hole may be formed in the substrate 23 at a position corresponding to the virtual projection area A, a temperature sensor may be embedded in the hole, and the temperature sensor may be brought into contact with the side surface 22 of the annular side portion 11 facing the reversible moving body 6. Alternatively, a hole may be formed axially penetrating the annular side portion 11 at a position corresponding to the virtual projection area A, and the temperature sensor may be mounted on the substrate surface facing the rolling body 6 of the substrate 23 so as to contact the step portion 18 through the hole. This makes it possible to shorten the heat conduction path between the first raceway surface portion 15 and the temperature sensor in the axial direction.

[0048] The one or more other sensors 26 are made of a circuit that converts a physical quantity or a chemical quantity other than temperature into an electric signal. The type of the other sensor 26 is not particularly limited. For example, at least one of a group consisting of an acceleration sensor and an AE (Acoustic Emission) sensor is included in the one or more other sensors 26. When an acceleration sensor is used, it is possible to detect radial or axial acceleration for monitoring vibration of the rolling bearing 1. When an AE sensor is used, it is possible to detect elastic waves when sound generated when a part of an object such as a component of the rolling bearing 1 is deformed or broken or when an impact is applied is emitted as an elastic wave (AE wave).

[0049] In addition, electronic components including a temperature sensor and an acceleration sensor may be adopted and placed in the virtual projection area A.

[0050] The wireless communication circuit 24 shown in Figures 4 and 5 is composed of a communication circuit that converts predetermined information, such as the results of detection by the temperature sensor 10 and one or more other sensors 26, into radio waves and radiates the radio waves from an antenna. The wireless communication circuit 24 complies with a predetermined communication protocol and is generally modular. To avoid a decrease in wireless communication performance, the antenna 24a of the wireless communication circuit 24 is not in contact with other members, such as a sealant.

[0051] The power supply circuit 25 is a circuit that converts the AC power generated by the stator 14 of the generator 3 into DC power used on the circuit board 8 .

[0052] The magnetic ring 13 shown in FIG. 1 has a magnet 29 magnetized with alternating north and south poles in the circumferential direction, and a core metal 30, as shown in FIGS. 2 and 4. The magnet 29 is formed of magnetic rubber extending in the circumferential direction. The magnet 29 is bonded to the core metal 30 all around in the circumferential direction. Vulcanization bonding can be used as the bonding method. The core metal 30 has a flange portion for increasing its rigidity. Although the magnet 29 is exemplified by a magnetic material magnetized with multiple poles, it may be composed of a plurality of permanent magnets.

[0053] As shown in Fig. 1, the magnetic ring 13 is fixed to fit into the stepped end 31 of the second raceway 5 so as not to protrude from the second raceway 5 in the axial direction. The magnetic ring 13 is fitted onto the outer periphery of the second raceway 5, so that the second raceway 5 and the magnetic ring 13 are arranged coaxially. The stepped end 31 of the second raceway 5 is a portion for securing an annular space capable of accommodating the sensor unit 2 and the magnetic ring 13 between the circumferential surface portion 19 of the first raceway 4 and the second raceway 5, and has a shape that radially expands the space between the circumferential surface portion 19 and the end of the second raceway 5 that faces the stepped end 31 in the radial direction.

[0054] 1 and 2 guides the magnetic flux emitted from the magnetic ring 13 with a yoke structure, and induces an AC voltage in the coil 32 within the yoke structure. The stator 14 is provided in the sensor unit 2.

[0055] The yoke structure of the stator 14 is made up of a holder 9 and a yoke member 33 combined with annular side portion 11 of the holder 9, as shown in FIGS.

[0056] The holder 9 and the yoke member 33 are each made of a magnetic material such as a steel plate. The yoke member 33 is formed from a single metal plate. The overall shape of the yoke member 33 is formed by press molding.

[0057] The holder 9 has a first claw pole portion 34 which is seamlessly and integrally formed and extends from the side of the annular side portion 11 opposite the mating portion 12 (the side farther from the mating portion 12, the lower side in Figure 2) to the same side as the mating portion 12 (the right side in Figure 2) in the axial direction at regular intervals in the circumferential direction.

[0058] The yoke member 33 has, integrally and seamlessly, an annular plate portion 35 radially opposed to the fitting portion 12, a side plate portion 36 extending radially from the anti-annular side portion 11 side of the annular plate portion 35 (the side farther from the annular side portion 11, the lower side in Figure 2) to the anti-fitting portion 12 side (the side farther from the annular side portion 11, the right side in Figures 2 and 5), and a second claw pole portion 37 extending axially from the side plate portion 36 at a regular interval in the circumferential direction toward the annular side portion 11 side (the left side in Figure 5).

[0059] The yoke structure of the stator 14 is formed by a first claw pole portion 34, an annular side portion 11, an annular plate portion 35, a side plate portion 36, and a second claw pole portion 37. The fitting portion 12 of the holder 9 forms the outer periphery of the sensor unit 2. The first claw pole portion 34 and the second claw pole portion 37 are located on the inner periphery of the sensor unit 2.

[0060] As shown in Figures 2 and 4, the first claw pole portion 34 and the second claw pole portion 37 face each other in the radial direction with an air gap between them and the magnet 29. The first claw pole portion 34 and the second claw pole portion 37 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 34 and the second claw pole portion 37 that are adjacent in the circumferential direction. The total number of the first claw pole portions 34 and the second claw pole portions 37 is equal to the number of poles of the magnet 29 (the total number of north poles and south poles).

[0061] As shown in Fig. 5, arc-shaped holes 38 that axially penetrate the annular side portion 11 are formed at multiple locations in the circumferential direction. Protrusions 39 that fit into the inner surfaces of the holes 38 protrude in the axial direction from the annular plate portion 35. As shown in Fig. 6, the annular plate portion 35 is abutted in the axial direction against the annular side portion 11 at substantially all portions except for the areas where these protrusions 39 are present.

[0062] 2 and 5, the coil 32 is wound around a bobbin 40. The coil 32 and the bobbin 40 are arranged all around the circumference in a space surrounded by the annular side portion 11, the side plate portion 36, the annular plate portion 35, the first claw pole portion 34, and the second claw pole portion 37.

[0063] At least a portion of the surface of the coil 32 and the bobbin 40 may be in contact with the claw pole portions 34, 37, the annular side portion 11, and the side plate portion 36. When protecting the magnet wire constituting the coil 32 for the purposes of insulation, heat resistance, dust resistance, moisture resistance, and chafing prevention, a varnish treatment may be adopted in which the coil 32 is coated by dipping the coil 32 in varnish or by dripping varnish onto the coil 32. Also, the bobbin 40 may be omitted.

[0064] The magnetic flux emanating from the N pole of the magnet 29 shown in Fig. 4, for example, enters the annular side portion 11 (or side plate portion 36) from the first claw pole portion 34 (or the second claw pole portion 37), passes through the annular plate portion 35, goes around the coil 32 to the side plate portion 36 (or the annular side portion 11), and returns to the S pole of the magnet 29 via the adjacent second claw pole portion 37 (or the first claw pole portion 34). When the positions of the N pole and the S pole of the magnet 29 are interchanged with the rotation of the second race 5 relative to the first race 4, the direction of the magnetic flux is reversed. The alternating magnetic field thus generated generates an AC voltage at both ends 41, 41 of the start and end of the winding of the coil 32.

[0065] Both ends 41, 41 of the coil 32 are connected to terminals 42, 42 provided on the substrate 23 through wiring holes formed slightly in the annular plate portion 35.

[0066] In assembling the sensor unit 2, as shown in FIG. 5, the bobbin 40 around which the coil 32 is wound is placed between the annular side portion 11 of the holder 9 and the side plate portion 36 of the yoke member 33, and the holder 9 and the yoke member 33 are assembled in the axial direction, and at this time, each protrusion 39 of the yoke member 33 is fitted into the corresponding hole 38 of the annular side portion 11. This fitting ensures that the holder 9 and the yoke member 33 are coaxial with each other, and the first claw pole portion 34 and the second claw pole portion 37 are arranged alternately in a predetermined phase with a gap in the circumferential direction. Therefore, the holder 9 and the yoke member 33 can be assembled appropriately without using a jig. It is preferable that the holes 38 and the protrusions 39 are each formed in three or more places.

[0067] After this assembly, the protrusion 39 is fixed to the inner surface of the hole 38. This fixing may be performed by, for example, press fitting, bonding, laser welding, or a combination of these.

[0068] It is also possible to omit the protrusions 39 and the holes 38. In this case, after the holder and the yoke member are coaxially aligned and phase-aligned using a jig (not shown), the butting portions of the annular side portion and the annular plate portion may be bonded or laser-welded from the outer periphery of the annular plate portion, or these may be fixed using a combination of these methods.

[0069] When holder 9 and yoke member 33 are fixed in the assembled state as described above, stator 14 is completed as shown in Figures 1 and 6. Note that, although an example has been shown in which annular plate portion 35 of yoke member 33 serves as a partition between the storage space for circuit board 8 and stator 14, it is also possible to provide a partition wall separate from the annular plate portion that divides the annular side portion of the holder into two regions in the radial direction, and to place the stator on the radial inside of that partition wall.

[0070] Next, the circuit board 8 is inserted onto the annular side portion 11, and the board 23 is fixed to the annular side portion 11 using a plurality of screws 27. At this time, the board surface opposite to the mounting surface of the temperature sensor 10, the wireless communication circuit 24, etc. is made to face the annular side portion 11. In order to insulate the holder 9 from the circuit board 8, an insulating sheet such as a polyimide film may be interposed between the board 23 and the annular side portion 11. The board 23 and the annular side portion 11 can also be fixed by adhesion using an adhesive, an adhesive sheet, etc., or by a combination of adhesion and screw fastening. When the adhesive, adhesive sheet, or insulating sheet is a component of the heat conduction path, it is preferable to use one with as good thermal conductivity as possible.

[0071] After the circuit board 8 is fixed to the annular side portion 11, an assembly process is performed in which the cover 43 is fitted between the fitting portion 12 and the annular plate portion 35 as shown in Figures 2 and 4. As a result, the cover 43 closes the opening between the fitting portion 12 and the annular plate portion 35 without contacting the circuit board 8, and the gap between the cover 43 and the circuit board 8 becomes filled with air. Note that there is no particular limit to the means for fixing the cover 43, but in order to improve the airtightness of the fitting portions between the cover 43 and the fitting portion 12 and between the cover 43 and the annular plate portion 35, an adhesive or a resin filler may be applied to the fitting portions.

[0072] The cover 43 is made of resin that does not contain metal. Even if the holder 9 and the yoke member 33 are made of metal, the cover 43 has radio wave permeability, so wireless communication using the antenna 24a is possible. It is also possible to seal the circuit board 8 by filling the opening between the fitting portion 12 and the annular plate portion 35 with a sealant without using the cover 43. In this case, since the antenna 24a is covered with the sealant, it is advisable to use a sealant with a low relative dielectric constant, such as a resin, to suppress shortening of the wavelength of radio waves due to the dielectric constant of the sealant.

[0073] After the cover 43 is fixed, as shown in Figures 1 and 2, the sensor unit 2 is fixed to the peripheral surface portion 19 of the first raceway 4 at the fitting portion 12. Meanwhile, the magnetic ring 13 is fixed to the outer periphery of the second raceway 5. The fixing means for them is press-fitting, bonding, or a combination of these. Since the first raceway 4 and the second raceway 5 are arranged coaxially, the sensor unit 2 and the magnetic ring 13 are also arranged coaxially.

[0074] Since the variation in the radial gap between the magnetic ring 13 fixed to the second raceway 5, which is a component of the radial bearing, and the stator 14 of the sensor unit 2 fixed to the first raceway 4, which is also a component of the radial bearing, is small, a stable amount of power can be generated by the generator 3 composed of the magnetic ring 13 and the stator 14, compared to the case where a magnetic ring is provided on the cage. Since the detection and wireless communication can be performed by the circuit board 8 using the generator 3 as a power source, the sensor unit 2 can be made wireless. Note that a storage battery may be mounted on the annular side portion 11 or the board 23 as an emergency power source. Also, the power source for making it wireless is not limited to a generator, and may be a storage battery that can be mounted on the sensor unit or a power receiving circuit of a wireless power supply device.

[0075] This bearing device (see Figures 1 and 2) is as described above and comprises a rolling bearing 1 having a first raceway 4, a second raceway 5, and a plurality of rolling elements 6 arranged between the first raceway 4 and the second raceway 5, and a sensor unit 2 having a circuit board 8 and a holder 9 for holding the circuit board 8, wherein the circuit board 8 has a temperature sensor 10, the holder 9 has an annular side portion 11 extending radially and an engagement portion 12 protruding axially from the annular side portion 11, and the first raceway 4 has an inner circumference 16 including a raceway surface portion (first raceway surface portion 15), a step portion 18 for receiving the holder 9 axially, and a peripheral surface portion 19 that engages with the engagement portion 12.

[0076] In particular, in this bearing device, the step portion 18 of the first raceway 4 axially receives the side surface 21 of the annular side portion 11 facing the rolling body 6 at a position axially opposite the raceway surface portion (first raceway surface portion 15), and the circuit board 8 is arranged on the side surface 22 of the annular side portion 11 facing the reversing moving body 6, so that the annular side portion 11 and the circuit board 8 can be arranged close to the raceway surface portion (first raceway surface portion 15).

[0077] This bearing device further includes a heat conduction path 28 that continues in the axial direction from the raceway surface portion (first raceway surface portion 15) to the circuit board 8 and includes a step portion 18 and annular side portion 11. Therefore, heat generated at the contact portion between the raceway surface portion (first raceway surface portion 15) and the rolling element 6 can reach the circuit board 8 quickly due to heat conduction along the path that connects the raceway surface portion (first raceway surface portion 15) and the circuit board 8 in a straight line in the axial direction.

[0078] In this way, this bearing device positions the annular side portion 11 and the circuit board 8 close to the raceway surface portion (first raceway surface portion 15) and allows the heat generated at the contact portion between the raceway surface portion (first raceway surface portion 15) and the rolling element 6 to reach the circuit board 8 quickly, thereby enabling the temperature change of the first raceway ring 4 to be detected quickly and accurately.

[0079] Furthermore, in this bearing device, the temperature sensor 10 is disposed at a position facing the raceway surface portion (first raceway surface portion 15) in the axial direction, and the heat conduction path 28 is continuous in the axial direction from the raceway surface portion (first raceway surface portion 15) to the temperature sensor 10, so that the heat conduction path 28 between the raceway surface portion (first raceway surface portion 15) and the temperature sensor 10 can be made particularly short. In other words, if the temperature sensor 10 is disposed so as not to face the first raceway surface portion 15 in the axial direction, even if the circuit board 8 has a portion facing the first raceway surface portion 15 in the axial direction, heat will be conducted radially through the board 23 from that portion to the temperature sensor 10, and this is undesirable because the heat conduction path from the first raceway surface portion 15 to the temperature sensor 10 will be longer than the heat conduction path 28 of this bearing device.

[0080] Furthermore, in this bearing device, the side surface 22 of the annular side portion 11 facing the reversible moving body 6 and the circuit board 8 are in contact with each other along the path of the heat conduction path 28, thereby eliminating the distance between the annular side portion 11 and the circuit board 8. This is advantageous in shortening the heat conduction path 28 compared to the case where the aforementioned adhesive or insulating sheet is interposed between the annular side portion 11 and the circuit board 8.

[0081] Furthermore, in this bearing device, the side surface 21 of the annular side portion 11 facing the rolling element 6 and the step portion 18 of the first raceway 4 are in contact with each other along the path of the heat conduction path 28, thereby eliminating the distance between the annular side portion 11 and the step portion 18. This is advantageous in shortening the heat conduction path 28 compared to the case where an adhesive or adhesive sheet is interposed between the annular side portion 11 and the step portion 18 to fix the holder 9.

[0082] Furthermore, in this bearing device, the annular side portion 11 of the holder 9 is formed from a metal plate, which gives the annular side portion 11 better thermal conductivity than a resin material, and also makes it possible to reduce the thickness of the annular side portion 11 in the axial direction, which is advantageous for shortening the heat conduction path 28.

[0083] In this bearing device, an example has been shown in which the first raceway 4 is the outer raceway, but it is also possible for the first raceway to be the inner raceway. As an example, a second embodiment is shown in Fig. 7. Note that, in the following, only the differences from the first embodiment will be described.

[0084] The first raceway ring 50 according to the second embodiment is made of an inner ring and has an outer circumference 54 including a raceway surface portion 51, a step portion 52, and a peripheral surface portion 53. The holder 55 has a fitting portion 57 arranged on the inner circumference of the sensor unit 56. The temperature sensor 59 of the circuit board 58 is arranged on the annular side portion 60, close to the fitting portion 57 side, so as to face the raceway surface portion 51 in the axial direction. This provides a heat conduction path 61 that is continuous in the axial direction from the raceway surface portion 51 to the circuit board 58 and the temperature sensor 59. The stator 62 is arranged on the outer circumference side of the sensor unit 56. The magnetic ring 63 is fixed to the inner circumference of the second raceway ring 64, which is made of an outer ring, and accordingly, a stepped end portion 65 is formed on the inner circumference of the second raceway ring 64.

[0085] The bearing device according to the second embodiment can quickly and accurately detect temperature changes in the first bearing ring 50 which is the inner ring.

[0086] 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]

[0087] 1. Rolling bearings 2, 56 Sensor unit 4, 50 First raceway 5, 64 Second raceway 6 Rolling elements 8, 58 Circuit Board 9, 55 Holder 10,59 Temperature Sensor 11, 60 Circular side 12, 57 Fitting part 15, 51 Raceway surface section 16 Inner Circumference 18, 52 step part 19, 53 Peripheral part 21 Side surface of the annular portion on the rolling element side 22 Side of the annular part on the inverted moving body side 28, 61 Heat conduction path 54 Circumference

Claims

1. a rolling bearing having a first raceway, a second raceway, and a plurality of rolling elements disposed between the first raceway and the second raceway; a sensor unit having a circuit board and a holder for holding the circuit board; the circuit board has a temperature sensor; The holder has an annular side portion extending in a radial direction and a fitting portion protruding in an axial direction from the annular side portion, In a bearing device, the first raceway has an inner periphery or an outer periphery including a raceway surface portion, a step portion that axially receives the holder, and a peripheral surface portion that fits with the fitting portion, the step portion of the first raceway axially receives a side surface of the annular side portion on a rolling element side at a position axially opposed to the raceway surface portion, The circuit board is disposed on a side surface of the annular side portion on a side of the inverted moving body, a heat conduction path that is continuous in the axial direction from the raceway surface portion to the circuit board and that includes the step portion and the annular side portion;

2. 2. The bearing device according to claim 1, wherein the temperature sensor is disposed at a position axially opposite to the raceway surface portion, and the heat conduction path is continuous in the axial direction from the raceway surface portion to the temperature sensor.

3. 3. The bearing device according to claim 1, wherein a side surface of the annular side portion facing the reversible moving body and the circuit board are in contact with each other on a path of the heat conduction path.

4. 3. The bearing device according to claim 1, wherein a side surface of said annular side portion facing the rolling elements and said step portion of said first race are in contact with each other on a path of said heat transfer path.

5. 3. The bearing device according to claim 1, wherein the annular side portion of the holder is formed of a metal plate.

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