Bearing device

Abstract

To provide a bearing device which can incorporate many electronic components and make the electronic components stably function for a long period.SOLUTION: A bearing device 1 is configured such that: a first bearing 24 and a second bearing 25 are arranged spaced from each other in the axial direction inside a cylindrical housing 23; a cylindrical inter-outer ring-seat 26 sandwiched between a first outer ring 32 of the first bearing 24 and a second outer ring 36 of the second bearing 25 in the axial direction is formed in a dual structure composed of an outer loop 26a and an inner loop 26b; a circuit 30 provided together with a sensor 29 in an internal space of the inter-outer ring-seat 26 is divided into a plurality of partial circuits; and a circuit board 30a mounted with the partial circuits is arranged so that a mounting surface thereof is parallel to the axial direction of the inter-outer ring-seat 26 and is fixed while a portion of the board is fitted into a groove 26e as a board fixing part provided in a side face of a flange part of the inner loop 26b.SELECTED DRAWING: Figure 2

Description

Technical Field

[0006] , , , , ,

[0001] This invention relates to a bearing device in which a sensor is attached to a spacer between two rolling bearings.

Background Art

[0002] In machine tools such as machining centers and lathes, and other industrial machines, a spindle device that rotatably supports a spindle (rotating shaft) to which an object such as a tool or a workpiece is attached is used. In the field of use of such spindle devices, there is a demand for higher spindle rotation speeds for improving machining accuracy and production efficiency, and higher functionality and performance of condition monitoring.

[0003] In order to meet the above needs, as a bearing device for supporting the spindle of a spindle device, a device incorporating various sensors has been proposed.

[0004] For example, the bearing device proposed in Patent Document 1 arranges two rolling bearings axially spaced inside a cylindrical housing, and inside an outer ring spacer incorporated between the outer rings of the two bearings, a sensor such as a vibration sensor or a temperature sensor and a circuit for processing the output of the sensor are provided, and by controlling a pump that discharges lubricating oil based on the output of each sensor, seizure of the bearing due to an increase in the spindle rotation speed is prevented.

[0005] In addition, a load sensor is attached to the outer ring spacer between two rolling bearings so that changes in load such as an increase in the preload due to heat generation of each bearing or a cutting load applied to the spindle from the outside can be detected, and many bearing devices with enhanced functionality and performance of condition monitoring have been put into practical use.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

[0007] By the way, in the bearing device described in Patent Document 1, the circuit that processes the sensor output is divided into multiple sub-circuits, and each of these sub-circuits is mounted separately on multiple flat circuit boards and connected to each other by electric wires.

[0008] Here, each circuit board is housed in the outer ring spacer such that the mounting surface (front and back) on which electronic components such as sensors and sub-circuits are mounted is parallel to the axial direction of the outer ring spacer. Compared to the case where the mounting surface is positioned perpendicular to the axial direction of the outer ring spacer, this allows for a larger mounting area and enables the mounting of more electronic components.

[0009] However, since the multiple circuit boards, which are connected to each other by electrical wires, are not fixed to the outer ring spacer and are positioned in a movable manner within the outer ring spacer, there is a risk that these unfixed circuit boards may repeatedly collide with the inner surface of the outer ring spacer due to vibrations during spindle rotation, potentially damaging the circuit boards themselves or the electronic components mounted on their mounting surfaces.

[0010] Therefore, the objective of this invention is to provide a bearing device that incorporates many electronic components and allows those electronic components to function stably for a long period of time. [Means for solving the problem]

[0011] To solve the above problems, this invention provides a first bearing and a second bearing arranged axially apart inside a cylindrical housing, wherein the first bearing has a first outer ring, a first inner ring rotatably mounted radially inward of the first outer ring, and a plurality of first rolling elements incorporated between the first outer ring and the first inner ring, and the second bearing has a second outer ring, a second inner ring rotatably mounted radially inward of the second outer ring, and a plurality of second rolling elements incorporated between the second outer ring and the second inner ring, wherein a cylindrical outer ring spacer is sandwiched axially between the first and second outer rings. In a bearing device in which the outer ring spacer is arranged in a manner such that the outer ring spacer consists of an outer ring that contacts the first outer ring and the second outer ring in the axial direction and an inner ring that is arranged radially inward of the outer ring, and a sensor and a circuit for processing the output of the sensor are provided in the space formed between the outer ring and the inner ring, the circuit is divided into a plurality of sub-circuits, each of which is mounted separately on a plurality of flat circuit boards and connected to each other by electric wires, and each of the circuit boards is fixed to a board fixing part provided on the outer ring spacer (Configuration 1).

[0012] According to the above configuration 1, by arranging multiple circuit boards on which partial circuits are mounted so that their mounting surfaces are parallel to the axial direction of the outer ring spacer, the mounting area of ​​each circuit board can be increased, allowing for the incorporation of many electronic components. Furthermore, since the circuit boards fixed to the board fixing portion of the outer ring spacer are not at risk of colliding with the outer ring spacer due to vibrations during the rotation of the rotating shaft supported by the bearing device, the electronic components can function stably for a long period of time.

[0013] Here, in the above configuration 1, the circuit can be configured to include a wireless communication module (configuration 2). A wireless communication antenna formed on a circuit board exhibits directivity, meaning that the radio wave intensity is strongest in the direction normal to the surface on which the antenna is formed. Therefore, when adopting configuration 2, it is preferable to position the circuit board on which the wireless communication module is mounted so that the mounting surface of the wireless communication module is perpendicular to the axial direction of the outer ring spacer (configuration 3). In this way, the direction in which the radio wave intensity of the wireless communication module is strongest becomes parallel to the axial direction of the bearing device, making it easier for the radio waves to reach the outside of the device incorporating the bearing device, and enabling more stable communication with external control devices, etc.

[0014] Furthermore, in any of the above configurations 1 to 3, if preload is applied to the first bearing and the second bearing, and the preload acts only on the outer ring of the outer ring spacer, it is desirable that the sensor be positioned in contact with the outer ring (configuration 4). In this way, changes in preload load, temperature changes of each bearing, and changes in vibration caused by bearing damage or manufacturing defects can be detected with greater sensitivity.

[0015] Furthermore, in any of the above configurations 1 to 4, it is desirable that the outer ring be made of metal or ceramic to provide high rigidity (configuration 5). Moreover, in any of the above configurations 1 to 5, it is desirable that the inner ring be made of resin, considering the ease of molding the substrate fixing portion (configuration 6).

[0016] Furthermore, in configuration 2 or 3 described above, it is desirable that the cover that closes one axial side of the space formed between the outer ring and the inner ring is made of a non-magnetic material (configuration 7). [Effects of the Invention]

[0017] As described above, the bearing device of this invention divides the circuit for sensor output processing into a plurality of sub - circuits, and fixes the circuit boards on which electronic components such as those sub - circuits are mounted to the board fixing portions of the outer - ring intermediate seat respectively. Therefore, it is possible to incorporate many electronic components, and there is no risk that each circuit board will collide with the outer - ring intermediate seat against vibrations or the like, and the electronic components can function stably for a long time.

Brief Description of the Drawings

[0018] [Figure 1] Cross - sectional view of a spindle device for a machine tool using the bearing device of an embodiment of this invention [Figure 2] Cross - sectional view showing an enlarged main part of FIG. 1 [Figure 3] Cross - sectional view of the outer - ring intermediate seat along the line III - III of FIG. 2 [Figure 4] Exploded perspective view of the outer - ring intermediate seat of FIG. 1 [Figure 5] Exploded perspective view of a modified example of the outer - ring intermediate seat of FIG. 1

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments of this invention will be described based on the drawings. FIG. 1 shows a spindle device for a machine tool using a bearing device 1 according to an embodiment of this invention. This spindle device includes a main shaft 2 of a machine tool, an outer cylinder 3 that houses the main shaft 2, a motor 4 that rotationally drives the main shaft 2, a bearing device 1 of an embodiment that rotatably supports the main shaft 2 on the front side in the axial direction (the left side in FIG. 1) from the motor 4, and a rear - side bearing device 5 that rotatably supports the main shaft 2 on the rear side in the axial direction from the motor 4.

[0020] The outer cylinder 3 is formed in a hollow cylindrical shape with both ends open, and houses the bearing device 1 and the motor 4 in order from the front side to the rear side in the axial direction. In FIG. 1, the part of the outer cylinder 3 that houses the bearing device 1 and the part that houses the motor 4 are integrally formed without a joint. However, the two parts may be formed separately and connected and fixed.

[0021] The main shaft 2 is inserted into the outer cylinder 3 in a state where the front end in its axial direction protrudes from the front end opening of the outer cylinder 3. A chuck (not shown) for gripping a tool or a workpiece is detachably attached to the front end of the main shaft 2. Further, a through hole 6 for axially slidably accommodating a drawbar (not shown) of a machine tool is formed axially through the main shaft 2.

[0022] The motor 4 has a rotor 7 attached to the outer periphery of the main shaft 2 and an annular stator 8 for applying a rotational force to the rotor 7. The rotor 7 has a rotor sleeve 9 fitted on the outer periphery of the main shaft 2 and a rotor core 10 fixed to the outer periphery of the rotor sleeve 9. The rotor core 10 is, for example, a laminate of electromagnetic steel sheets. The rotor sleeve 9 is prevented from rotating relative to the main shaft 2 so as to rotate integrally with the main shaft 2. The front end in the axial direction of the rotor sleeve 9 contacts a stepped portion 11 having a stepped surface facing the rear side in the axial direction formed on the outer periphery of the main shaft 2, and is axially positioned by contacting the stepped portion 11.

[0023] The stator 8 has a stator core 12 fixed to the inner periphery of the outer cylinder 3 and electromagnetic coils 13 respectively wound around a plurality of tooth portions formed at intervals in the circumferential direction on the stator core 12. When the electromagnetic coils 13 are energized, a rotational force is generated in the rotor core 10 by the electromagnetic force acting between the stator core 12 and the rotor core 10, and the rotor 7 and the main shaft 2 rotate integrally. Here, an electromagnetic motor that generates a rotational force by electric power is adopted as the motor 4, but it is also possible to adopt a motor of a type that generates a rotational force by another power source such as compressed air instead of the electromagnetic motor.

[0024] The rear bearing device 5 has an annular bearing support member 14 coaxially fixed to the rear end of the outer cylinder 3 and a rolling bearing 15 mounted on the inner periphery of the bearing support member 14. The rolling bearing 15 is a cylindrical roller bearing having an outer ring 16 fitted on the inner periphery of the bearing support member 14, an inner ring 17 fitted on the outer periphery of the main shaft 2, and a plurality of cylindrical rollers 18 incorporated between the outer ring 16 and the inner ring 17.

[0025] An outer ring retaining member 19 is attached to the bearing support member 14. The outer ring retaining member 19 fixes the axial position of the outer ring 16 by contacting the axial rear side surface of the outer ring 16. A nut member 20 that presses the inner ring 17 axially forward and an annular spacer 21 incorporated between the inner ring 17 and the nut member 20 are mounted on the outer circumference of the main shaft 2. The nut member 20 is screw-connected to a female thread 22 formed on the outer circumference of the rear end of the main shaft 2. The axial front end of the spacer 21 contacts the axial rear side surface of the inner ring 17, and the axial rear end contacts the axial front side surface of the nut member 20. The axial front end of the inner ring 17 is in contact with the axial rear end of the rotor sleeve 9.

[0026] As shown in Figures 1 and 2, the bearing device 1 includes a housing 23 fixed to the outer cylinder 3, a first bearing 24 fitted to the inner circumference of the housing 23, a second bearing 25 fitted to the inner circumference of the housing 23 axially rearward from the first bearing 24, and an outer ring spacer 26 and an inner ring spacer 27 sandwiched axially between the first bearing 24 and the second bearing 25, with the first bearing 24 and the second bearing 25 supporting the main shaft 2.

[0027] The first bearing 24 is an angular contact ball bearing having a non-rotating first outer ring 32 fitted to the inner circumference of the housing 23, a first inner ring 33 rotatably provided radially inward of the first outer ring 32, a plurality of first rolling elements (in this case, balls) 34 incorporated between the first outer ring 32 and the first inner ring 33, and a cage 35 that holds the first rolling elements 34 so as to be able to roll.

[0028] The second bearing 25 is an angular contact ball bearing having a non-rotating second outer ring 36 positioned axially rearward from the first outer ring 32 and fitted to the inner circumference of the housing 23, a second inner ring 37 rotatably provided radially inward of the second outer ring 36, a plurality of second rolling elements (in this case, balls) 38 incorporated between the second outer ring 36 and the second inner ring 37, and a cage 39 that holds the second rolling elements 38 so as to be able to roll.

[0029] Here, in the first bearing 24, the line connecting the contact point between the first inner ring 33 and the first rolling element 34 and the contact point between the first outer ring 32 and the first rolling element 34 is inclined axially backward from the radially inward to the radially outward direction. On the other hand, in the second bearing 25, the line connecting the contact point between the second inner ring 37 and the second rolling element 38 and the contact point between the second outer ring 36 and the second rolling element 38 is inclined axially forward from the radially inward to the radially outward direction. In other words, the first bearing 24 and the second bearing 25 are arranged in a back-to-back configuration.

[0030] As shown in Figures 1 to 4, the outer ring spacer 26 consists of a metal outer ring 26a that fits onto the inner circumference of the housing 23, and a resin inner ring 26b that is positioned radially inward of the outer ring 26a. The outer ring 26a is formed in a hollow cylindrical shape with both ends open, and three protrusions 26a1 are provided at equal intervals in the circumferential direction on the inner circumference of the axial center. In addition, two lubricant supply passages 26c that penetrate radially are provided at predetermined circumferential positions between the protrusions 26a1.

[0031] On the other hand, the inner ring 26b has a protrusion on a part of the outer circumference of a hollow cylindrical section that is open at both ends, and two nozzles 26d are provided on this protrusion, each communicating with a lubricant supply passage 26c of the outer ring 26a. The portion other than the circumferential position where the protrusion is formed is formed in an L-shape in cross-section with an outward-facing flange at the axial rear end of the cylindrical section, and this protrusion and flange are fixed to the inner circumferential surface of the outer ring 26a. As a means of fixing, the protrusion and flange of the inner ring 26b can be pressed into the inner circumferential surface of the outer ring 26a or bonded, and these methods can also be used in combination. Furthermore, an annular groove is provided around the connection portion of each nozzle 26d with the lubricant supply passage 26c, and an O-ring 28 fitted into the annular groove prevents leakage of lubricant (and liquid oil-proof protective material filled at the time of initial assembly). Note that a sealing material may be filled instead of the O-ring 28.

[0032] Furthermore, the outer ring 26a is formed with an axial dimension larger than that of the inner ring 26b. As a result, the axial front end of the outer ring 26a contacts the axial rear side surface of the first outer ring 32, and the axial rear end contacts the axial front side surface of the second outer ring 36. On the other hand, the inner ring 26b does not contact the first outer ring 32 or the second outer ring 36, and is positioned axially by the axial front side surface 26b1 of the flange portion contacting the inner circumference convex portion 26a1 of the outer ring 26a.

[0033] Furthermore, a sensor 29 and a circuit 30 for processing the output of the sensor 29 are provided in the space formed between the cylindrical portions of the outer ring 26a and the inner ring 26b. The sensor 29 is, for example, a load sensor, a vibration sensor, or a temperature sensor, and is mounted on the inward-facing plane of each protrusion 26a1 on the inner circumference of the outer ring 26a. The circuit 30 consists of a sensor signal processing unit, a low-pass / high-pass filter, an amplifier, a power supply, and a wireless communication module, and is divided into multiple sub-circuits, each of which is separately mounted on multiple rectangular flat circuit boards 30a, 30b (30b is for the wireless communication module) and connected to each other by wires 30c. The sensor 29 is also connected to the circuit 30 by wires 30c.

[0034] Here, the circuit boards 30a on which the partial circuits other than the wireless communication module are mounted are all positioned so that their mounting surfaces (front and back) are parallel to the axial direction of the outer ring spacer 26. Only the circuit board 30b on which the wireless communication module is mounted is positioned so that its mounting surface is perpendicular to the axial direction of the outer ring spacer 26, so that the direction normal to the circuit board surface on which the antenna is formed, i.e., the direction in which the radio wave intensity of the wireless communication module is strongest, is parallel to the axial direction of the bearing device 1. Then, each of the circuit boards 30a and 30b is partially fitted into grooves 26e and 26f, which serve as substrate fixing parts, provided on the axial front side surface 26b1 of the flange portion of the inner ring 26b, and fixed with adhesive.

[0035] Furthermore, a cover 31 is provided on the axial front side of the outer ring spacer 26, which fits between the inner surface of the outer ring 26a and the outer surface of the cylindrical part of the inner ring 26b, thereby preventing oil containing foreign matter from entering the space between the outer ring 26a and the inner ring 26b (the space around the sensor 29 and circuit 30). The cover 31 is fixed to the outer ring 26a and the inner ring 26b with adhesive, and this adhesive also serves as a sealant to prevent oil from entering. Considering the ease of wireless communication, it is desirable that the material of this cover 31 be a non-magnetic material with a low relative permittivity and dielectric loss tangent.

[0036] Furthermore, since it is desirable for the outer ring 26a to be highly rigid, it was made of metal in the example above, but it may also be made of ceramic. On the other hand, the inner ring 26b can be made of metal or ceramic, but considering the ease of molding the substrate fixing part, it is desirable to form it of resin as in the example above. Also, in the example above, the sensor 29 is directly attached to the plane of the protrusion 26a1 on the inner circumference side of the outer ring 26a, but it is also possible to attach a substrate with the sensor mounted on it to the outer ring and connect the substrate and the circuit with wires.

[0037] Next, as shown in Figures 1 and 2, the inner ring spacer 27, like the outer ring 26a of the outer ring spacer 26, is formed in a hollow cylindrical shape with both ends open, its axial front end contacting the axial rear side surface of the first inner ring 33, and its axial rear end contacting the axial front side surface of the second inner ring 37.

[0038] An outer ring retaining member 40 is fixed to the axial front end of the outer cylinder 3, which fixes the axial position of the first outer ring 32 by contacting the axial front side surface of the first outer ring 32. The outer ring retaining member 40 has a cylindrical portion 41 that fits onto the inner circumference of the housing 23, and a flange portion 42 that extends radially outward from the axial front end of the cylindrical portion 41. The flange portion 42 is fixed to the axial front side surface of the housing 23. In addition, a stepped portion 43 is formed on the outer circumference of the axial front end of the main shaft 2, which contacts the axial front side surface of the first inner ring 33. The first inner ring 33 is positioned axially by contact with this stepped portion 43.

[0039] A preload nut 44 that presses the second inner ring 37 axially forward is mounted on the outer circumference of the spindle 2, and an annular spacer 45 is fitted between the second inner ring 37 and the preload nut 44. The preload nut 44 is screw-connected to a female thread 46 formed on the portion of the spindle 2 that extends axially forward from the stepped portion 11 on the outer circumference of the spindle 2. The axial front end of the spacer 45 contacts the axial rear side surface of the second inner ring 37, and the axial rear end contacts the axial front side surface of the preload nut 44. A stepped portion 47 is formed on the inner circumference of the housing 23 that contacts the axial rear side surface of the second outer ring 36. The second outer ring 36 is positioned axially by contact with this stepped portion 47.

[0040] The housing 23 has a cylindrical portion 48 that fits onto the inner circumference of the outer cylinder 3, and a flange portion 49 that extends radially outward from the axial front end of the cylindrical portion 48. Cooling grooves 50 are formed on the outer circumference of the cylindrical portion 48 through which a refrigerant for cooling the bearing device 1 flows. The cooling grooves 50 are a plurality of annular grooves formed at axial intervals on the outer circumference of the cylindrical portion 48, or helical grooves that extend spirally around the outer circumference of the cylindrical portion 48. The flange portion 49 is fixed in contact with the axial front end of the outer cylinder 3.

[0041] The spindle device for this machine tool has the above configuration, and when the bearing device 1 is assembled, the preload nut 44 is tightened, and the axial force is transmitted sequentially to the spacer 45, the second inner ring 37, the second rolling element 38, the second outer ring 36, the outer ring spacer 26a, the first outer ring 32, the first rolling element 34, and the first inner ring 33, and is received by the stepped portion 43 of the spindle 2, thereby applying preload to the first bearing 24 and the second bearing 25. Furthermore, when a machining load is applied to the spindle 2 by machining, the machining load is transmitted sequentially to the stepped portion 43 of the spindle 2, the first inner ring 33, the first rolling element 34, the first outer ring 32, the outer ring spacer 26a, and the second outer ring 36, and is received by the stepped portion 47 on the inner circumference of the housing 23. Therefore, by using a load sensor 29 attached to the outer ring 26a, preload and cutting loads can be detected with high sensitivity.

[0042] Furthermore, in this embodiment, the bearing device 1 has a double structure in which the outer ring spacer 26 consists of an outer ring 26a and an inner ring 26b, and the circuit 30 provided in the internal space of the outer ring spacer 26 together with the sensor 29 is divided into multiple sub-circuits, and of the circuit boards 30a and 30b on which each sub-circuit is mounted, the circuit board 30a on which the sub-circuits other than the wireless communication module are mounted is arranged so that its mounting surface (front and back) is parallel to the axial direction of the outer ring spacer 26. Compared to the case where the mounting surface is arranged perpendicular to the axial direction of the outer ring spacer 26, a larger mounting area can be obtained, and it is possible to incorporate many electronic components.

[0043] Furthermore, the circuit board 30b on which the wireless communication module is mounted is positioned so that its mounting surface is perpendicular to the axial direction of the outer ring spacer 26, and the direction in which the radio wave strength of the wireless communication module is strongest is parallel to the axial direction of the bearing device 1. As a result, the radio waves can easily reach the outside of the spindle device into which the bearing device 1 is incorporated, enabling stable communication with external control devices, etc.

[0044] Furthermore, since each circuit board 30a and 30b is fixed to the inner ring 26b of the outer ring spacer 26, there is no risk of collision with the outer ring 26a or inner ring 26b even when subjected to vibrations during the rotation of the main shaft 2, and the electronic components mounted on each circuit board 30a and 30b can be made to function stably for a long period of time.

[0045] Figure 5 shows a modified example of the outer ring spacer 26 shown in Figures 1 to 4. In this modified example of the outer ring spacer 26, three recesses 26a2 are provided on the inner circumference of the outer ring 26a at equal intervals in the circumferential direction. Each of these recesses 26a2 is formed to extend along the entire axial length of the outer ring 26a for ease of processing, and a sensor 29 is attached to the axial center of each recess.

[0046] The inner ring 26b is bonded and fixed to the outer ring 26a in such a way that three protrusions 26b2 provided on the outer circumference of its flange portion fit into the respective recesses 26a2 of the outer ring 26a. The axial positioning of the inner ring 26b relative to the outer ring 26a is performed by aligning the lubricant supply passage 26c of the outer ring 26a with the nozzle 26d of the inner ring 26b by passing a jig (not shown) through them.

[0047] Furthermore, the lid 31 is fixed to the outer ring 26a by adhesive bonding after the outer ring 26a and inner ring 26b are bonded together, with three protrusions 31a on its outer circumference fitting into the respective recesses 26a2 of the outer ring 26a. The axial positioning of the lid 31 is performed by bringing the axial rear side of the lid 31 into contact with a plurality of protrusions 26b3 provided on the axial front outer circumference of the inner ring 26b.

[0048] Since the configuration of this modified example is the same as that of Figures 1 to 4, including the arrangement of each circuit board 30a and 30b and how they are fixed to the inner ring 26b, the same effects can be achieved by using this modified example as by using the example in Figures 1 to 4.

[0049] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended.

[0050] For example, the outer ring spacer that constitutes the bearing device can have a double structure consisting of an outer ring and an inner ring, so the outer ring and inner ring may be separate parts as in the embodiment, or they may be formed integrally.

[0051] Furthermore, in the embodiment, the circuit board on which the wireless communication module is mounted is positioned so that its mounting surface is perpendicular to the axial direction of the outer ring spacer. However, it is not limited to this, and it is acceptable to position it so that the direction in which the radio wave intensity is strongest is parallel to the axial direction of the bearing device.

[0052] Furthermore, the bearing device of this invention can be effectively applied not only to spindle devices for machine tools as in the embodiment, but also to various machine tools and equipment having a rotating shaft. [Explanation of Symbols]

[0053] 1. Bearing device 2 spindle 3. Outer cylinder 4 motors 23 Housing 24 First bearing 25 Second bearing 26 Outer wheel spacer 26a outer ring 26b inner ring 26e, 26f groove (board fixing part) 29 sensors 30 circuits 30a, 30b Circuit board 30c electric wire 31 Lid 32 First outer ring 33 First Inner Ring 34. First Rolling Element 36. Second outer ring 37 Second inner ring 38. Second rolling element

Claims

1. A first bearing (24) and a second bearing (25) are arranged inside a cylindrical housing (23) with an axial gap between them. The first bearing (24) comprises a first outer ring (32), a first inner ring (33) rotatably mounted radially inward of the first outer ring (32), and a plurality of first rolling elements (34) incorporated between the first outer ring (32) and the first inner ring (33). The second bearing (25) comprises a second outer ring (36), a second inner ring (37) rotatably mounted radially inward of the second outer ring (36), and a plurality of second rolling elements (38) incorporated between the second outer ring (36) and the second inner ring (37). A cylindrical outer ring spacer (26) is positioned axially between the first outer ring (32) and the second outer ring (36). The outer ring spacer (26) consists of an outer ring (26a) that contacts the first outer ring (32) and the second outer ring (36) in the axial direction, and an inner ring (26b) that is positioned radially inward of the outer ring (26a). In a bearing device in which a sensor (29) and a circuit (30) for processing the output of the sensor (29) are provided in the space formed between the outer ring (26a) and the inner ring (26b), The circuit (30) is divided into a plurality of sub-circuits, and each of these sub-circuits is mounted separately on a plurality of flat circuit boards (30a, 30b) and connected to each other by electric wires (30c). Each of the circuit boards (30a, 30b) is fixed to a board fixing portion (26e, 26f) provided on the outer ring spacer (26), The circuit (30) includes a wireless communication module. The bearing device is characterized in that the circuit board (30b) on which the wireless communication module is mounted is positioned such that the mounting surface of the wireless communication module is perpendicular to the axial direction of the outer ring spacer (26).

2. The bearing device according to claim 1, wherein preload is applied to the first bearing (24) and the second bearing (25), the preload acts only on the outer ring (26a) of the outer ring spacer (26), and the sensor (29) is positioned in contact with the outer ring (26a).

3. The bearing device according to claim 1 or 2, wherein the outer ring (26a) is formed of metal or ceramic.

4. The bearing device according to claim 1 or 2, wherein the inner ring (26b) is made of resin.

5. The bearing device according to claim 1 or 2, wherein the cover (31) that closes one axial side of the space formed between the outer ring (26a) and the inner ring (26b) is made of a non-magnetic material.

6. A first bearing (24) and a second bearing (25) are arranged inside a cylindrical housing (23) with an axial gap between them. The first bearing (24) comprises a first outer ring (32), a first inner ring (33) rotatably mounted radially inward of the first outer ring (32), and a plurality of first rolling elements (34) incorporated between the first outer ring (32) and the first inner ring (33). The second bearing (25) comprises a second outer ring (36), a second inner ring (37) rotatably mounted radially inward of the second outer ring (36), and a plurality of second rolling elements (38) incorporated between the second outer ring (36) and the second inner ring (37). A cylindrical outer ring spacer (26) is positioned axially between the first outer ring (32) and the second outer ring (36). The outer ring spacer (26) consists of an outer ring (26a) that contacts the first outer ring (32) and the second outer ring (36) in the axial direction, and an inner ring (26b) that is positioned radially inward of the outer ring (26a). In a bearing device in which a sensor (29) and a circuit (30) for processing the output of the sensor (29) are provided in the space formed between the outer ring (26a) and the inner ring (26b), The circuit (30) is divided into a plurality of sub-circuits, and each of these sub-circuits is mounted separately on a plurality of flat circuit boards (30a, 30b) and connected to each other by electric wires (30c). Each of the circuit boards (30a, 30b) is fixed to a board fixing portion (26e, 26f) provided on the outer ring spacer (26), A bearing device characterized in that preload is applied to the first bearing (24) and the second bearing (25), the preload acts only on the outer ring (26a) of the outer ring spacer (26), and the sensor (29) is positioned in contact with the outer ring (26a).

7. The bearing device according to claim 6, wherein the outer ring (26a) is formed of metal or ceramic.

8. The bearing device according to claim 6 or 7, wherein the inner ring (26b) is made of resin.

9. The bearing device according to claim 6 or 7, wherein the cover (31) that closes one axial side of the space formed between the outer ring (26a) and the inner ring (26b) is made of a non-magnetic material.

10. A first bearing (24) and a second bearing (25) are arranged inside a cylindrical housing (23) with an axial gap between them. The first bearing (24) comprises a first outer ring (32), a first inner ring (33) rotatably mounted radially inward of the first outer ring (32), and a plurality of first rolling elements (34) incorporated between the first outer ring (32) and the first inner ring (33). The second bearing (25) comprises a second outer ring (36), a second inner ring (37) rotatably mounted radially inward of the second outer ring (36), and a plurality of second rolling elements (38) incorporated between the second outer ring (36) and the second inner ring (37). A cylindrical outer ring spacer (26) is positioned axially between the first outer ring (32) and the second outer ring (36). The outer ring spacer (26) consists of an outer ring (26a) that contacts the first outer ring (32) and the second outer ring (36) in the axial direction, and an inner ring (26b) that is positioned radially inward of the outer ring (26a). In a bearing device in which a sensor (29) and a circuit (30) for processing the output of the sensor (29) are provided in the space formed between the outer ring (26a) and the inner ring (26b), The circuit (30) is divided into a plurality of sub-circuits, and each of these sub-circuits is mounted separately on a plurality of flat circuit boards (30a, 30b) and connected to each other by electric wires (30c). Each of the circuit boards (30a, 30b) is fixed to a board fixing portion (26e, 26f) provided on the outer ring spacer (26), The circuit (30) includes a wireless communication module. A bearing device characterized in that a cover (31) that closes one axial side of the space formed between the outer ring (26a) and the inner ring (26b) is made of a non-magnetic material.

11. The bearing device according to claim 10, wherein the outer ring (26a) is formed of metal or ceramic.

12. The bearing device according to claim 10 or 11, wherein the inner ring (26b) is made of resin.

Images