Bearing device

Abstract

To enable measured data to be transmitted to the outside wirelessly without forming a space for facilitating propagation of electric waves in a housing in a bearing device including a wireless communication device.SOLUTION: A bearing device 10 comprises: a housing 25 that accommodates a main shaft 40 therein; a bearing 50a; a metal lid part 30; and a communication device 71. The bearing 50a has an inner ring 52a and an outer ring 51a, and rotatably supports the main shaft 40 with respect to the housing 25. The lid part 30 is fitted to an inner diameter surface of the housing 25 in a state of being in contact with an axial end surface of the housing 25 and an axial end surface of the outer ring 51a. The communication device 71 is disposed in a region facing the lid part 30 with the bearing 50a therebetween, and performs wireless communication using electric waves. A through-hole 85 penetrating in an axial direction of the main shaft 40 is formed in the lid part 30. The through-hole 85 is provided with a sealing member 80 formed of a non-magnetic material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a bearing assembly equipped with a wireless communication device. [Background technology]

[0002] Machines that include rolling or oscillating mechanisms, such as those used in machine tool spindles, are sometimes fitted with detection devices such as sensors to control or monitor the condition of the machine. In particular, in machines that use rolling bearings, it is effective to detect characteristics near the bearings inside the machine, so it is desirable to place various sensors, such as vibration sensors and temperature sensors, near the bearings inside the machine.

[0003] Furthermore, conventionally, electrical wires are often used to transmit data detected by sensors, but placing electrical wires inside a machine can lead to interference with other mechanisms inside the machine and reduced functionality of those mechanisms (for example, reduced dimensional accuracy and reduced shape accuracy).It can also make the machine harder to assemble, which can be a factor in reducing productivity.

[0004] To address the above-mentioned problems, for example, Japanese Patent Laid-Open Publication No. 2003-28151 (Patent Document 1) discloses a bearing device in which a wireless sensor with an antenna is attached to the outer ring of the bearing, and data detected by this wireless sensor is transmitted wirelessly to the outside via radio waves.In this bearing device, in light of the fact that the bearing and its peripheral parts (housing, lid, etc.) are made of metal (magnetic material) which does not easily propagate radio waves, a space (hole or groove) is formed inside the housing located around the part where the wireless sensor is attached, to make it easier for the radio waves transmitted from the wireless sensor to propagate to the outside. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-28151 Summary of the Invention [Problem to be solved by the invention]

[0006] In the bearing device disclosed in Japanese Patent Laid-Open No. 2003-28151 (Patent Document 1), a space (hole or groove) for facilitating the propagation of radio waves is formed inside a housing arranged around the bearing.

[0007] However, since other mechanisms for cooling the bearings are usually provided inside the housing around the bearings, it may not be possible to create sufficient space inside the housing if there is interference with other mechanisms. Furthermore, creating a space with a complex shape inside the housing to avoid interference with other mechanisms can lead to concerns about a deterioration in the shape precision of the housing and an increase in costs.

[0008] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to enable a bearing device equipped with a wireless communication device to transmit measurement data wirelessly to the outside without having to form a special space inside the housing to facilitate the propagation of radio waves. [Means for solving the problem]

[0009] (1) A bearing device according to the present disclosure includes a cylindrical housing that accommodates a rotating body therein, a first bearing, a lid, and a communication device. The first bearing has an inner ring fixed to the outer diameter surface of the rotating body and an outer ring fixed to the inner diameter surface of the housing, and supports the rotating body rotatably relative to the housing. The lid is made of a metal material. The lid is fitted to the inner diameter surface of the housing while contacting the axial end surface of the housing and the axial end surface of the outer ring. The communication device is disposed in an area facing the lid across the first bearing, and performs wireless communication using radio waves. The lid is formed with at least one through hole that penetrates the rotating body in the axial direction. A sealing member made of a non-magnetic material is provided in the at least one through hole.

[0010] (2) In one embodiment, when the cover is viewed from the axial direction of the rotor, each of the at least one through-holes is formed at a position a first distance from the center of the rotor's axis. The first dimension of each through-hole in the circumferential direction relative to the center of the rotor's axis is equal to or greater than 1 / 10 of the wavelength of the radio waves used in wireless communication of the communication device. The sum of the first dimensions of the at least one through-hole is less than 1 / 2 of the length of a circumference whose radius is the first distance.

[0011] (3) In one embodiment, when a cross section passing through each through hole and taken along the rotation axis of the rotor is viewed, the through hole has a crank shape.

[0012] (4) In one embodiment, when the cover is viewed from the axial direction of the rotor, the sealing member at least partially overlaps with the outer ring.

[0013] (5) In one embodiment, the communication device is capable of communicating with an external device via wireless communication. The bearing device further includes an antenna at least a portion of which is disposed within the sealing member. The antenna receives radio waves from the communication device and transmits them to the external device.

[0014] (6) In one embodiment, the communication device is disposed in a region between a first bearing and a second bearing disposed opposite the lid with the first bearing in between. The bearing device further includes a self-power generating device disposed in a region between the first bearing and the second bearing and configured to supply power to the communication device.

[0015] (7) In one embodiment, the non-magnetic material includes a resin or a ceramic.

[0016] (8) In one embodiment, the first bearing is an angular contact ball bearing.

[0017] (9) In one embodiment, the rotating body is a main spindle of a machine tool. [Effects of the Invention]

[0018] According to the present disclosure, in a bearing device equipped with a wireless communication device, measurement data can be transmitted wirelessly to the outside without having to form a special space inside the housing to facilitate the propagation of radio waves. [Brief explanation of the drawings]

[0019] [Figure 1] 1A and 1B are a cross-sectional view and a side view showing a schematic configuration of a spindle device including a bearing device according to a first embodiment. [Figure 2] FIG. 2 is a block diagram showing an example of the configuration of a communication module. [Figure 3] 10 is a cross-sectional view showing a schematic configuration of a spindle device including a bearing device of a first modified example. FIG. [Figure 4] FIG. 10 is a cross-sectional view showing a schematic configuration of a spindle device including a bearing device according to a second modification. [Figure 5] FIG. 10 is a cross-sectional view showing a schematic configuration of a spindle device including a bearing device according to a third modified example. [Figure 6] FIG. 10 is a cross-sectional view showing a schematic configuration of a spindle device including a bearing device according to a second embodiment. [Figure 7] FIG. 10 is a cross-sectional view showing a schematic configuration of a spindle device including a bearing device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0021] [Embodiment 1] FIG. 1 is a side view (left diagram a) and a cross-sectional view (right diagram b) showing a schematic configuration of a spindle device 1 including a bearing device 10 according to the first embodiment.

[0022] The spindle device 1 shown in Fig. 1 is used, for example, as a spindle device with a built-in motor for a machine tool. In this case, a motor (not shown) is built into one end (the right side of the cross-sectional view in Fig. 1) of a spindle 40 supported by the spindle device 1 for the machine tool spindle, and a cutting tool (not shown), such as an end mill, is connected to the other end (the left side of the cross-sectional view in Fig. 1). As an example, the diameter of the spindle 40 is set to 70 mm, and the maximum rotational speed of the spindle 40 is set to 20,000 rpm.

[0023] The spindle device 1 includes a bearing device 10. The bearing device 10 includes a bearing 50 including two bearings 50a and 50b, and a spacer 60 disposed between the bearings 50a and 50b. The main shaft 40 is provided inside a cylindrical housing 25 embedded in the inner diameter portion of the outer cylinder 20, and is rotatably supported by the bearings 50a and 50b. A groove 26 that functions as a coolant flow path is formed in the housing 25. The bearings 50a and 50b can be cooled by flowing a coolant between the outer cylinder 20 and the housing 25.

[0024] The bearing 50a is a rolling bearing including a metal outer ring 51a, a metal inner ring 52a, a plurality of rolling elements 53a disposed between the outer ring 51a and the inner ring 52a, and a cage 54a. The plurality of rolling elements 53a are spaced apart by the cage 54a.

[0025] Bearing 50b is a rolling bearing including a metal outer ring 51b, a metal inner ring 52b, a plurality of rolling elements 53b disposed between outer ring 51b and inner ring 52b, and a cage 54b. The plurality of rolling elements 53b are spaced apart by cage 54b.

[0026] The rolling elements 53a and 53b are made of a non-magnetic material such as silicon nitride.

[0027] An inner ring 52a of a bearing 50a and an inner ring 52b of a bearing 50b, which are spaced apart in the axial direction, are fitted onto the main shaft 40 in an interference fit (press-fit) state.

[0028] The spacer 60 includes an outer ring spacer 61 and an inner ring spacer 62. The outer ring spacer 61 is disposed between the outer ring 51a and the outer ring 51b. The inner ring spacer 62 is disposed between the inner ring 52a and the inner ring 52b.

[0029] The bearings 50a, 50b may be angular contact ball bearings, deep groove ball bearings, tapered roller bearings, cylindrical roller bearings, or the like. The bearing device 10 shown in FIG. 1 uses angular contact ball bearings, and the two bearings 50a, 50b are installed in a back-to-back (DB) configuration. The bearing arrangement is not limited to back-to-back configuration, and may be, for example, face-to-face configuration. In this specification, a structure in which the main shaft 40 is supported by two bearings 50a, 50b is described as an example, but the main shaft 40 may also be supported by two or more bearings.

[0030] The lid 30 is an annular member for suppressing axial displacement of the housing 25 relative to the bearing 50a. The lid 30 is fitted to the inner diameter surface of the housing 25 while contacting an end face on one axial side of the housing 25 (the left side of the right diagram b in FIG. 1) and an end face on one axial side of the outer ring 51a. The lid 30 supports the load from the housing 25 and the bearing 50 and is therefore made of a metal material that can withstand the load.

[0031] A through-hole 85 is formed in the lid 30, penetrating in the direction of the rotation axis of the main shaft 40. When viewed from the direction of the rotation axis of the main shaft 40, the through-hole 85 is formed in an arc shape at a distance R1 from the rotation axis center SP, and a sealing member 80 made of a non-magnetic material such as resin or ceramics is disposed inside the through-hole. The sealing member 80 may be made of any non-metallic material that allows radio waves to pass through. For example, the sealing member 80 may be made of a resin material such as PEEK (polyether ether ketone) or PPS (polyphenylene sulfide), or may be made of a material reinforced with carbon fiber or glass fiber, or may be made of glass or rubber. The material of the sealing member 80 is preferably selected taking into consideration compatibility with the metal lid (differences in expansion / contraction due to temperature changes, thermal expansion coefficient), strength, cost, availability, etc.

[0032] 1 (right diagram b), through-hole 85 is formed at a position along the inner diameter surface of housing 25, and sealing member 80 reaches outer ring 51a of bearing 50a. In other words, when viewed from the direction of the rotation axis of main shaft 40, sealing member 80 at least partially overlaps outer ring 51a.

[0033] The inner diameter portion of lid portion 30 is shaped to fit into a recess formed in spindle 40 while being spaced apart from spindle 40. This shape forms a so-called "labyrinth structure," in which small, complicated spaces are formed between spindle 40 and lid portion 30. This labyrinth structure allows spindle 40 to rotate relative to fixed lid portion 30, while preventing cutting powder generated by cutting and coolant used during cutting from penetrating into the spindle.

[0034] A communication module 70 with a built-in sensor is disposed between bearing 50a and bearing 50b. More specifically, the communication module 70 is attached to the outer ring spacer 61 in a state where it is exposed on the end face of the outer ring spacer 61 on the bearing 50a side (cutting tool side) in the axial direction. Note that a communication module similar to the communication module 70 may also be provided on the end face of the outer ring spacer 61 on the bearing 50b side (motor side) in the axial direction.

[0035] Fig. 2 is a block diagram showing an example of the configuration of the communication module 70. The communication module 70 incorporates a communication device 71, a power generation device 72, and at least one sensor 73 for controlling the spindle 40 and / or monitoring the state of the bearing device 10. In the example of Fig. 2, the sensors 73 include a heat flow sensor 731 for measuring heat flux, a temperature sensor 732 for measuring temperature, a vibration sensor 733 for measuring vibration, and a load sensor 734 for measuring the bearing preload, cutting load, and / or load transmitted from the spindle 40. Note that the sensors 73 may include sensors other than those described above.

[0036] The communication device 71 is connected to each sensor by wire and collects data indicating the detection results of each sensor. Alternatively, the communication device 71 may be connected to each sensor wirelessly and collect data indicating the detection results of each sensor wirelessly.

[0037] The communication device 71 transmits the data collected from each sensor to an external device 100 provided outside the bearing device 10 by wireless communication using radio waves. In the first embodiment, the communication device 71 complies with the Bluetooth (registered trademark) communication standard, and wirelessly transmits data indicating the detection results of each sensor to the external device 100 using radio waves in the 2.4 GHz frequency band.

[0038] The power generation device 72 is connected to the communication device 71 and generates power for driving the communication device 71. For example, a thermoelectric element (Peltier element) that generates power by the Seebeck effect can be used as the power generation device 72. Note that when power is required to drive a sensor, the power generation device 72 may supply power from the power generation device 72 to the corresponding sensor.

[0039] Here, it is assumed that the external device 100 for receiving data from the communication module 70 is positioned axially outside the bearing 50a (to the left of the bearing 50a in the right-hand diagram b of FIG. 1), i.e., on the tool side. Therefore, the bearing 50a is located between the communication device 71 and the external device 100. As described above, the rolling elements 53a of the bearing 50a are not made of metal but are formed of a non-magnetic material such as silicon nitride (Si3N4). Therefore, the radio waves emitted from the communication module 70 pass through the rolling elements 53a made of silicon nitride and reach the minute space between the bearing 50a and the lid 30. The radio waves that reach this minute space are then radiated to the outside of the bearing device 10 via the sealing member 80 made of a non-magnetic material.

[0040] The arc length L1 (first dimension) of the through-hole 85 is set to λ / 10 or more, where λ is the wavelength of the radio waves transmitted from the communication module 70. This allows the radio waves transmitted from the communication module 70 to pass through the sealing member 80 arranged inside the through-hole 85.

[0041] Furthermore, when a plurality of through holes 85 are formed in lid portion 30, the sum of the arc lengths L1 of the respective through holes 85 is set to less than ½ of the circumferential length of a circle whose radius is the distance R1 (first distance) from rotation axis center SP of main shaft 40. As described above, lid portion 30 needs to support the load from housing 25 and bearing 50. Therefore, by setting the sum of the arc lengths L1 of through holes 85 to less than ½ of the circumferential length, it is possible to maintain the desired load-bearing capacity.

[0042] In recent years, machine tools have increasingly been used to process difficult-to-cut materials such as titanium and / or perform high-speed, heavy-duty cutting to improve productivity, leading to an increase in wet cutting using high-pressure coolant. Therefore, to prevent coolant from seeping into the spindle 40, the labyrinth structure between the cover 30 and the spindle 40 has become more complex and narrower. This can make it difficult for radio waves to pass through the gaps in the labyrinth structure.

[0043] Also, in order to ensure a path for radio waves to pass through, it is possible to configure the structure so that a non-magnetic member is placed between the axial end face of the housing 25 and the lid 30. However, because it is necessary to support the load at the contact surface between the lid 30 and the housing 25, the dimensional accuracy and deformation of the non-magnetic member placed between the housing 25 and the lid 30 can significantly affect the magnitude of the preload applied to the bearing 50 or changes in that preload during operation.

[0044] In bearing device 10 of embodiment 1, lid portion 30 is formed with through-hole 85 penetrating in the axial direction, and through-hole 85 is provided with sealing member 80 made of a non-magnetic material. With this configuration, a path for radio waves can be ensured without impairing the axial load-bearing capacity of lid portion 30. Furthermore, the space existing in the path from communication module 70 to sealing member 80 is the space necessary to configure bearing 50a and a space for ensuring clearance to prevent contact between spindle 40 and bearing 50a. Therefore, in bearing device 10 of embodiment 1, a path for radio waves can be ensured without the need to specially form a space to facilitate propagation of radio waves to the outside.

[0045] The "main shaft 40" in the first embodiment corresponds to the "rotating body" in the present disclosure. The "bearing 50a" and the "bearing 50b" in the first embodiment correspond to the "first bearing" and the "second bearing" in the present disclosure.

[0046] <Modification> In the following modified examples, variations in the arrangement of the through holes formed in the lid portion will be described.

[0047] (Variation 1) In the first embodiment, a configuration has been described in which the cross section of the through hole formed in the lid along the rotation axis is linear. In the first modification, an example of a configuration in which the through hole is bent inside the lid will be described.

[0048] 3 is a cross-sectional view showing a schematic configuration of a spindle device 1A including a bearing device 10A of Modified Example 1. A through-hole 85A in a lid portion 30A of the bearing device 10A has a crank shape when viewed in a cross section passing through the through-hole 85A and along the rotation axis. A sealing member 80 is provided inside the through-hole 85A. Even with this shape of through-hole, radio waves can be emitted to the outside via the sealing member 80.

[0049] By forming the through-hole 85A in a crank shape, when the sealing member 80 is placed or when the lid portion 30A is attached to the housing 25, the sealing member 80 can be prevented from slipping out of the through-hole.

[0050] (Variation 2) In the second modification, a configuration will be described in which the position of the through hole from the center of the rotation axis of the lid portion is changed.

[0051] 4 is a cross-sectional view showing a schematic configuration of a spindle device 1B equipped with a bearing device 10B of Modified Example 2. Compared to through-hole 85 of Embodiment 1, through-hole 85B of lid portion 30B in bearing device 10B is formed in a position slightly offset toward the center of the rotation shaft, and penetrates partway through the labyrinth structure. Therefore, sealing member 80 disposed in through-hole 85B does not contact outer ring 51a of bearing 50a, but rather contacts the metal portion of lid portion 30B.

[0052] Generally, the metal material of the lid portion 30B has a higher load-bearing capacity than the material forming the sealing member 80. Therefore, by configuring the lid portion 30B of the bearing device 10B as described above, the axial load-bearing capacity of the lid portion 30B can be improved.

[0053] (Variation 3) In the third modification, a configuration in which the shape of the inner diameter portion of the lid is changed will be described.

[0054] 5 is a cross-sectional view showing a schematic configuration of a spindle device 1C including a bearing device 10C of Modification 3. In the bearing device 10C, the position of the through-hole 85 in the lid portion 30C is formed in the same position as in Embodiment 1. However, the lid portion 30C has a stepped structure in which a protrusion 35 for supporting the sealing member 80 is formed inside the sealing member 80.

[0055] In bearing device 10 of embodiment 1, most of the inner surface of sealing member 80 is exposed to the space within the bearing device. Therefore, when cover 30 is attached to housing 25, if axial compressive force is applied to sealing member 80 due to contact between sealing member 80 and outer ring 51a, sealing member 80 may buckle or bend, causing partial protrusion in the space (i.e., toward the rotating shaft). This may cause contact between sealing member 80 and spindle 40 or peeling of sealing member 80, which could result in a malfunction.

[0056] On the other hand, in the bearing device 10C of the third modification, the sealing member 80 is supported by the protrusion 35 located inside the sealing member 80, which prevents deformation of the sealing member 80 when the cover 30 is attached to the housing 25. This makes it possible to prevent failures in the bearing device 10C.

[0057] [Embodiment 2] In the second embodiment, a configuration will be described in which an antenna 90 for receiving radio waves from a communication module 70 is disposed in a sealing member 80.

[0058] 6 is a cross-sectional view showing a schematic configuration of a spindle device 1D equipped with a bearing device 10D according to embodiment 2. The bearing device 10D has a configuration in which an antenna 90 is added to the configuration of the bearing device 10 of embodiment 1.

[0059] Antenna 90 has an overall rod-like shape, and at least a portion of it is disposed within sealing member 80 provided in through-hole 85. Antenna 90 may be a monopole antenna, or, when using radio waves of relatively high frequencies, such as millimeter waves or higher frequencies, it may be configured with a flat patch antenna attached to the tip of a rod-shaped member.

[0060] The antenna 90 may be connected to the external device 100 by a cable, or may further communicate wirelessly with the external device 100. When wireless communication is performed, a relay device (not shown) may be further provided for wirelessly transmitting a signal received by the antenna 90 from the communication module 70.

[0061] By arranging such a receiving antenna 90, the signal transmitted from the communication module 70 can be transmitted to the external device 100 more reliably.

[0062] [Embodiment 3] In the first and second embodiments, a configuration was described in which a through hole is formed in the cover portion located on the end face of the housing in the main axis direction, and radio waves transmitted from the communication module are radiated to the outside through the through hole.

[0063] In the third embodiment, a configuration will be described in which radio waves from the communication module are radiated to the outside through a through hole formed in the radial direction of the housing.

[0064] 7 is a cross-sectional view showing a schematic configuration of a spindle device 1E including a bearing device 10E according to a third embodiment. In the bearing device 10E, no through-hole is formed in the lid portion 30. Instead, a through-hole 85E is formed in the radial direction of the housing 25 and the outer cylinder 20, and a sealing member 80E made of a non-magnetic material is provided inside the through-hole 85E. Note that, in order not to impede cooling of the bearing 50, the through-hole 85E is formed in a portion of the housing 25 where the groove portion 26 is not present.

[0065] Furthermore, the communication module 70 is arranged so as to be exposed on the outer peripheral surface in the radial direction of the outer ring spacer 61, and is positioned so as to overlap with the through hole 85E on the outer peripheral surface of the outer ring spacer 61. With this configuration, radio waves from the communication module 70 propagate through the sealing member 80E inside the through hole 85E and are radiated to the outside.

[0066] With this configuration, it is also possible to transmit measurement data wirelessly to the outside without forming a special space inside the housing to facilitate the propagation of radio waves.

[0067] In the bearing device 10E of the third embodiment, similarly to the bearing device 10D of the second embodiment, a receiving antenna may be disposed inside the sealing member 80E of the through hole 85E.

[0068] [Aspect] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0069] (Item 1) A bearing device according to one aspect includes a cylindrical housing that accommodates a rotor, a first bearing, a lid, and a communication device. The first bearing has an inner ring fixed to the outer diameter surface of the rotor and an outer ring fixed to the inner diameter surface of the housing, and supports the rotor rotatably relative to the housing. The lid is made of a metal material. The lid is fitted to the inner diameter surface of the housing while contacting the axial end surface of the housing and the axial end surface of the outer ring. The communication device is located in an area facing the lid across the first bearing, and performs wireless communication using radio waves. The lid is formed with at least one through hole that penetrates the rotor in the axial direction. A sealing member made of a non-magnetic material is provided in the at least one through hole.

[0070] (Item 2) In the bearing device described in item 1, when the cover is viewed from the axial direction of the rotating body, each of the at least one through-hole is formed at a position a first distance from the center of the rotating shaft of the rotating body. The first dimension in the circumferential direction of each through-hole relative to the center of the rotating shaft is equal to or greater than 1 / 10 of the wavelength of the radio waves used in wireless communication of the communication device. The sum of the first dimensions of the at least one through-hole is less than 1 / 2 of the length of a circumference whose radius is the first distance.

[0071] (Item 3) In the bearing device described in item 2, when a cross section passing through each through hole and along the rotation axis of the rotor is viewed, the through hole has a crank shape.

[0072] (Item 4) In the bearing device according to any one of items 1 to 3, when the cover is viewed from the axial direction of the rotor, the sealing member at least partially overlaps with the outer ring.

[0073] (Item 5) In the bearing device described in any one of Items 1 to 4, the communication device is capable of communicating with an external device via wireless communication. The bearing device further includes an antenna, at least a portion of which is disposed within the sealing member. The antenna receives radio waves from the communication device and transmits them to the external device.

[0074] (Item 6) In the bearing device described in any one of Items 1 to 5, the communication device is arranged in a region between the first bearing and a second bearing arranged in a position facing the lid with the first bearing in between. The bearing device further includes a self-power generating device arranged in the region between the first bearing and the second bearing, which supplies power to the communication device.

[0075] (7) In the bearing device according to any one of the above items 1 to 6, the non-magnetic material includes resin or ceramics.

[0076] (Item 8) In the bearing device according to any one of items 1 to 7, the first bearing is an angular contact ball bearing.

[0077] (Item 9) In the bearing device according to any one of items 1 to 8, the rotating body is a main shaft of a machine tool.

[0078] (Item 10) A bearing device according to one aspect includes a cylindrical housing that accommodates a rotor, a first bearing, a lid, and a communication device. The first bearing has an inner ring fixed to the outer diameter surface of the rotor and an outer ring fixed to the inner diameter surface of the housing, and supports the rotor rotatably relative to the housing. The lid is fitted to the inner diameter surface of the housing while contacting the axial end face of the housing and the axial end face of the outer ring. The communication device is disposed in an area facing the lid across the first bearing, and performs wireless communication using radio waves. The housing is formed with a through hole that penetrates in the radial direction of the rotor. A sealing member made of a non-magnetic material is provided in the through hole. The sealing member is in contact with the communication device.

[0079] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0080] 1, 1A to 1E Spindle device, 10, 10A to 10E Bearing device, 20 Outer cylinder, 25 Housing, 26 Groove portion, 30, 30A to 30C Cover portion, 35 Protrusion portion, 40 Main shaft, 50, 50a, 50b Bearing, 51a, 51b Outer ring, 52a, 52b Inner ring, 53a, 53b Rolling element, 54a, 54b Cage, 60 Spacer, 61 Outer ring spacer, 62 Inner ring spacer, 70 Communication module, 71 Communication device, 72 Power generation device, 73 Sensor, 80, 80E Sealing member, 85, 85A, 85B, 85E Through hole, 90 Antenna, 100 External device, 731 Heat flow sensor, 732 Temperature sensor, 733 Vibration sensor, 734 Load sensor, SP Center of rotation axis.

Claims

1. a cylindrical housing that accommodates a rotating body therein; a first bearing having an inner ring fixed to an outer diameter surface of the rotating body and an outer ring fixed to an inner diameter surface of the housing, the first bearing supporting the rotating body rotatably relative to the housing; a cover portion formed of a metal material and fitted to an inner diameter surface of the housing in contact with an axial end surface of the housing and an axial end surface of the outer ring; a communication device that is disposed in a region facing the lid portion across the first bearing and that performs wireless communication using radio waves, At least one through hole is formed in the cover portion, the through hole passing through the cover portion in the axial direction of the rotor, A bearing device, wherein the at least one through hole is provided with a sealing member made of a non-magnetic material.

2. When the cover portion is viewed from the axial direction of the rotating body, each of the at least one through-holes is formed at a position a first distance from a rotation axis center of the rotating body, a first dimension in a circumferential direction of each through hole with respect to the center of the rotation axis is equal to or greater than 1 / 10 of the wavelength of a radio wave used in wireless communication of the communication device, The bearing device according to claim 1 , wherein the sum of the first dimensions of the at least one through hole is less than half the length of a circumference having a radius equal to the first distance.

3. 3. The bearing device according to claim 2, wherein when viewed in a cross section passing through each through hole and taken along the rotation axis of the rotating body, the through hole has a crank shape.

4. 4. The bearing device according to claim 1, wherein the sealing member at least partially overlaps the outer ring when the cover is viewed in the axial direction of the rotating body.

5. the communication device is capable of communicating with an external device via wireless communication; The bearing device according to any one of claims 1 to 3, further comprising an antenna, at least a portion of which is disposed within the sealing member, for receiving radio waves from the communication device and transmitting the radio waves to the external device.

6. the communication device is disposed in a region between the first bearing and a second bearing disposed at a position facing the lid portion with the first bearing interposed therebetween, The bearing device according to any one of claims 1 to 3, further comprising a self-power generating device disposed in a region between the first bearing and the second bearing and supplying power to the communication device.

7. 4. The bearing device according to claim 1, wherein the non-magnetic material includes a resin or a ceramic.

8. 4. The bearing device according to claim 1, wherein the first bearing is an angular contact ball bearing.

9. 4. The bearing device according to claim 1, wherein the rotating body is a main shaft of a machine tool.

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