Bearing device

Abstract

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 radio waves. A through-hole (85) penetrating in the 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.

Description

Bearing device

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

[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 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.

[0005] Japanese Patent Application Laid-Open No. 2003-28151

[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.

[0009] (1) A bearing device according to a first aspect of 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 rotatably supports the rotating body 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 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 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 aspect, when the cover 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 the center of the rotation axis of the rotating body. A first circumferential dimension of each through-hole relative to the center of the rotation axis is equal to or greater than 1 / 10 of the wavelength of 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 having a radius equal to the first distance.

[0011] (3) In one aspect, 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 aspect, 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) A bearing device according to a second aspect of the present disclosure includes a cylindrical housing that accommodates a rotating body therein, a first bearing, a lid, a communication device, and an antenna. 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 rotatably supports the rotating body 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. A through hole is formed in the housing that penetrates the rotating body in the radial direction. The antenna is disposed within the through hole and receives radio waves from the communication device and transmits them to an external device. The antenna is disposed so as to overlap the communication device in the radial direction of the spindle.

[0015] (7) In one embodiment, a sealing member made of a non-magnetic material is provided in at least a portion of the inside of the through hole.

[0016] (8) In one aspect, the communication device is disposed in a region between a first bearing and a second bearing disposed in a position facing the cover across the first bearing. 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.

[0017] (9) In one aspect, the non-magnetic material includes a resin or a ceramic. (10) In one aspect, the first bearing is an angular contact ball bearing.

[0018] (11) In one aspect, the rotating body is a main spindle of a machine tool.

[0019] 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.

[0020] FIG. 1 is a cross-sectional view and a side view showing a schematic configuration of a spindle device including a bearing device according to embodiment 1. FIG. 2 is a block diagram showing an example of the configuration of a communication module. FIG. 3 is a cross-sectional view showing a schematic configuration of a spindle device including a bearing device according to modified example 1. FIG. 4 is a cross-sectional view showing a schematic configuration of a spindle device including a bearing device according to modified example 2. FIG. 5 is a cross-sectional view showing a schematic configuration of a spindle device including a bearing device according to modified example 3. FIG. 6 is a cross-sectional view showing a schematic configuration of a spindle device including a bearing device according to embodiment 2. FIG. 7 is a cross-sectional view showing a schematic configuration of a spindle device including a bearing device according to embodiment 3. FIG. 8 is a cross-sectional view showing a schematic configuration of a spindle device including a bearing device according to embodiment 4. FIG. 9 is a cross-sectional view showing a schematic configuration of a spindle device including a bearing device according to modified example 4. FIG. 10 is a cross-sectional view showing a schematic configuration of a spindle device including a bearing device according to modified example 5.

[0021] 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.

[0022] First Embodiment 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 a first embodiment.

[0023] The spindle device 1 shown in Fig. 1 is used, for example, as a built-in motor type spindle device for a machine tool. In this case, a motor (not shown) is built into one end (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 (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.

[0024] 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. The housing 25 is formed with a groove 26 that functions as a coolant flow path. The bearings 50a and 50b can be cooled by flowing a coolant between the outer cylinder 20 and the housing 25.

[0025] 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.

[0026] The 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 the outer ring 51b and the inner ring 52b, and a cage 54b. The plurality of rolling elements 53b are spaced apart by the cage 54b.

[0027] The rolling elements 53a and 53b are made of a non-magnetic material such as silicon nitride.

[0028] 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.

[0029] 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 51 a and the outer ring 51 b. The inner ring spacer 62 is disposed between the inner ring 52 a and the inner ring 52 b.

[0030] 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.

[0031] 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.

[0032] A through-hole 85 is formed in the lid 30, penetrating in the direction of the rotational axis of the main shaft 40. When viewed from the direction of the rotational axis of the main shaft 40, the through-hole 85 is formed in an arc shape at a distance R1 from the rotational axis center SP. 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 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, and the like.

[0033] 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 51 a of bearing 50 a. 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 51 a.

[0034] 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.

[0035] 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.

[0036] 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 sensor 73 may include sensors other than those described above.

[0037] 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.

[0038] The communication device 71 transmits data collected from each sensor by wireless communication using radio waves to an external device 100 provided outside the bearing device 10. In the first embodiment, the communication device 71 complies with communication standards such as Wi-Fi or Bluetooth (registered trademark), 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.

[0039] 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. 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.

[0040] Here, it is assumed that the external device 100 for receiving data from the communication module 70 is disposed axially outside the bearing 50a (to the left of the bearing 50a in the right 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 mentioned above, the rolling elements 53a of the bearing 50a are not made of metal but of silicon nitride (Si ３ N ４ ). 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 nonmagnetic material.

[0041] The arc length L1 (first dimension) of the through hole 85 is set to be 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 in the through hole 85.

[0042] 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 be less than half the length of the circumference having a radius equal to the distance R1 (first distance) from the rotation axis center SP of spindle 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 be less than half the length of the circumference, it is possible to maintain the desired load-bearing capacity.

[0043] 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.

[0044] 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 disposed 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 disposed between the housing 25 and the lid 30 can significantly affect the magnitude of the preload applied to the bearing 50 or changes in the preload during operation.

[0045] In bearing device 10 of embodiment 1, a through-hole 85 is formed in lid portion 30, penetrating in the axial direction, and a sealing member 80 made of a non-magnetic material is provided in through-hole 85. 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 present 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 main shaft 40 and bearing 50a. Therefore, in bearing device 10 of embodiment 1, a path for radio waves can be ensured without the need to specifically form a space to facilitate propagation of radio waves to the outside.

[0046] 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.

[0047] <Modifications> In the following modifications, variations in the arrangement of the through holes formed in the lid will be described.

[0048] In the first embodiment, the through hole formed in the lid has a linear cross section along the rotation axis. In the first modification, an example of a configuration in which the through hole is bent inside the lid will be described.

[0049] 3 is a cross-sectional view showing a schematic configuration of a spindle device 1A equipped with a bearing device 10A according to Modification 1. The through-hole 85A in the lid 30A of the bearing device 10A has a crank shape when viewed in cross section along the rotation axis passing through the through-hole 85A. A sealing member 80 is provided within the through-hole 85A. Even with this shape of the through-hole, radio waves can be emitted to the outside via the sealing member 80.

[0050] By forming the through hole 85A in a crank shape, it is possible to prevent the sealing member 80 from slipping out of the through hole when placing the sealing member 80 or when attaching the lid portion 30A to the housing 25.

[0051] (Modification 2) In Modification 2, a configuration in which the position of the through hole from the center of the rotation axis of the lid portion is changed will be described.

[0052] 4 is a cross-sectional view showing the schematic configuration of a spindle device 1B equipped with a bearing device 10B according to Modification 2. The through-hole 85B of the lid portion 30B in the bearing device 10B is formed at a position slightly offset toward the center of the rotation shaft compared to the through-hole 85 of Embodiment 1, and penetrates partway through the labyrinth structure. Therefore, the sealing member 80 disposed in the through-hole 85B does not contact the outer ring 51a of the bearing 50a, but rather contacts the metal portion of the lid portion 30B.

[0053] 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.

[0054] (Modification 3) In Modification 3, a configuration in which the shape of the inner diameter portion of the lid is changed will be described.

[0055] 5 is a cross-sectional view showing a schematic configuration of a spindle device 1C including a bearing device 10C according to Modification 3. In the bearing device 10C, the position of the through-hole 85 in the lid portion 30C is the same 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.

[0056] 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 could result in contact between sealing member 80 and main shaft 40 or peeling of sealing member 80, which could cause a malfunction.

[0057] On the other hand, in the bearing device 10C of the third modification, the sealing member 80 is supported by the protrusion 35 located on the inside of 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 malfunctions of the bearing device 10C.

[0058] Second Embodiment In a 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.

[0059] 6 is a cross-sectional view showing a schematic configuration of a spindle device 1D including 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.

[0060] 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.

[0061] 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.

[0062] By arranging such a receiving antenna 90, it becomes possible to transmit the signal transmitted from the communication module 70 to the external device 100 more reliably.

[0063] [Embodiment 3] In embodiments 1 and 2, a configuration was described in which a through hole is formed in a lid 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.

[0064] 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.

[0065] 7 is a cross-sectional view showing a schematic configuration of a spindle device 1E equipped with a bearing device 10E according to a third embodiment. In the bearing device 10E, no through-hole is formed in the lid 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 26 is not present.

[0066] Furthermore, the communication module 70 is disposed so as to be exposed on the outer peripheral surface of the outer ring spacer 61 in the radial direction, 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.

[0067] 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.

[0068] In the bearing device 10E of embodiment 3, a receiving antenna may be disposed inside the sealing member 80E of the through-hole 85E, as in the bearing device 10D of embodiment 2. In the case of the bearing device 10E, the rolling elements 53a, 53b may be formed from a metal material.

[0069] Fourth Embodiment In a fourth embodiment and modifications 3 and 4 described below, a configuration will be described in which a through hole is formed in the radial direction of the housing, as in the third embodiment, and an antenna is disposed in the through hole.

[0070] FIG. 8 is a cross-sectional view showing a schematic configuration of a spindle device 1F including a bearing device 10F according to a fourth embodiment.

[0071] 8 , in bearing device 10F, outer cylinder 20 and housing 25 are formed with a radial through-hole 86 at a position corresponding to communication module 70. When through-hole 86 is viewed from the outer periphery of outer cylinder 20 along the radial direction of main shaft 40, through-hole 86 overlaps so as to radially overlap communication module 70 and main shaft 40, and more preferably, so as to radially overlap communication device 71 and main shaft 40. In other words, through-hole 86 is arranged so that the axial coordinate positions and circumferential coordinate positions of communication module 70, and more preferably, communication device 71, and main shaft 40 are the same. In other words, when through-hole 86 is viewed from the outer periphery of outer cylinder 20 along the radial direction of main shaft 40, through-hole 86 overlaps communication module 70, and more preferably, communication device 71. Note that, in order not to impede cooling of bearing 50, through-hole 86 is formed in a portion of housing 25 where groove portion 26 is not present.

[0072] In bearing device 10F of embodiment 4, a sealing member 81 made of a nonmagnetic material is filled in the portion of through-hole 86 that contacts communication module 70. Furthermore, an antenna 90 for receiving signals transmitted from communication device 71 included in communication module 70 is disposed inside through-hole 86. When antenna 90 is viewed from the outer periphery of outer cylinder 20 along the radial direction of main shaft 40, antenna 90 overlaps communication module 70 so as to overlap with communication device 71 in the radial direction of main shaft 40, and more preferably, overlaps with communication device 71 in the radial direction of main shaft 40. In other words, antenna 90 is disposed so that the axial coordinate position and circumferential coordinate position of communication module 70, and more preferably, communication device 71, and main shaft 40 are the same. In other words, when antenna 90 is viewed from the outer periphery of outer cylinder 20 along the radial direction of main shaft 40, antenna 90 overlaps communication module 70, and more preferably, overlaps with communication device 71.

[0073] Antenna 90 has an overall rod-like shape, and at least a portion of it is disposed within sealing member 81 that fills through-hole 86. Antenna 90 may be a monopole antenna, or, when using radio waves of relatively high frequencies, such as millimeter waves or higher, it may be configured with a flat patch antenna attached to the tip of a rod-shaped member.

[0074] The antenna 90 may be connected to the external device 100 by wire using a cable, or may further communicate wirelessly with the external device 100. When communicating with the external device 100 wirelessly, a relay device (not shown) may be further provided for wirelessly transmitting a signal received by the antenna 90 from the communication device 71.

[0075] By arranging the receiving antenna 90 in this manner, it becomes possible to more reliably transmit signals transmitted from the communication module 70 to the external device 100. In particular, by configuring the through-hole 85 formed in the housing 25 to be in contact with the communication module 70, it becomes unnecessary to form a special space inside the housing to facilitate the propagation of radio waves. Therefore, this configuration makes it possible to reduce the size of the device without impeding the cooling of the bearing.

[0076] The "main shaft 40" in the fourth embodiment corresponds to the "rotating body" in the present disclosure. The "bearing 50a" and the "bearing 50b" in the fourth embodiment correspond to the "first bearing" and the "second bearing" in the present disclosure.

[0077] <Modifications> In the following Modifications 4 and 5, variations in the arrangement of the sealing member disposed in the through-hole will be described.

[0078] (Modification 4) Figure 9 is a cross-sectional view showing a schematic configuration of a spindle device 1G including a bearing device 10G according to modification 4. In bearing device 10G, a sealing member 82 is disposed throughout a through-hole 86 formed in outer cylinder 20 and housing 25. Note that other configurations in Figure 9 are similar to those of bearing device 10F according to embodiment 4 shown in Figure 8, and therefore description of those overlapping elements will not be repeated.

[0079] In the bearing device 10G, the sealing member 82 is disposed not only in the portion of the through hole 86 that contacts the communication module 70 but also in the entire through hole 86, thereby preventing the through hole 86 from being clogged with foreign matter such as dust or chips, and preventing corrosion or contamination of the inner surfaces of the through hole 85 in the housing 25 and the outer cylinder 20 due to moisture entering the through hole 86. In addition, it is possible to prevent a decrease in communication quality due to the adhesion of metallic foreign matter to the outer diameter surface of the antenna 90, and / or corrosion or contamination of the outer diameter surface of the antenna 90. Furthermore, compared to the bearing device 10 of the first embodiment, the fixation of the antenna 90 inside the through hole 86 can be strengthened.

[0080] 10 is a cross-sectional view showing a schematic configuration of a spindle device 1H equipped with a bearing device 10H according to Modification 5. In the bearing device 10H, a sealing member 83 is disposed in a portion of the through-hole 86 on the side closer to the outer peripheral surface of the outer cylinder 20. In other words, a space is formed inside the through-hole 86 between the sealing member 83 and the communication module 70. Even with this configuration, it is possible to prevent foreign matter such as dust or chips, and moisture, from entering the through-hole 86.

[0081] Furthermore, because cooling water flows through the housing 25 to cool the bearing 50 and spacer 60 inside the housing 25, it is preferable to have as much direct contact between the housing 25 and these components as possible in order to improve cooling efficiency. In the bearing device 10B, a space is formed between the communication module 70 and the antenna 90, but the extent of this space is limited to the area inside the through-hole 85. Therefore, the effect on cooling efficiency due to the formation of the space can be limited.

[0082] 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.

[0083] REFERENCE SIGNS LIST 1, 1A to 1H Spindle device, 10, 10A to 10H 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 to 83, 80E Sealing member, 85, 85A, 85B, 85E, 86 Through hole, 90 Antenna, 100 External device, 731 Heat flow sensor, 732 Temperature sensor, 733 Vibration sensor, 734 Load sensor, SP rotation axis center.

Claims

1. A bearing device comprising: a cylindrical housing that accommodates a rotating body; a first bearing having 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 supporting the rotating body rotatably relative to the housing; a lid made of a metallic material and 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; and a communication device that is located in an area facing the lid across the first bearing and performs wireless communication using radio waves, wherein the lid has at least one through hole that passes through the rotating body in the axial direction, and the at least one through hole is provided with a sealing member made of a non-magnetic material.

2. A bearing device as described in claim 1, wherein, 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 rotational axis of the rotating body, a first circumferential dimension of each through-hole relative to the center of the rotational axis is equal to or greater than 1 / 10 of the wavelength of the radio waves used in wireless communication of the communication device, and the sum of the first dimensions of the at least one through-hole is less than 1 / 2 of the length of a circumference having a radius equal to the first distance.

3. A bearing device according to claim 2, wherein 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.

4. A bearing device according to any one of claims 1 to 3, wherein when the cover portion is viewed from the axial direction of the rotating body, the sealing member at least partially overlaps with the outer ring.

5. A bearing device according to any one of claims 1 to 4, wherein the communication device is capable of communicating with an external device via wireless communication, and the bearing device further comprises an antenna, at least a portion of which is disposed within the sealing member, for receiving radio waves from the communication device and transmitting them to the external device.

6. A bearing device comprising: a cylindrical housing that accommodates a rotating body inside; a first bearing having 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 supporting the rotating body rotatably relative to the housing; a lid that 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; and a communication device that is arranged in an area facing the lid across the first bearing and performs wireless communication using radio waves, wherein a through hole that passes through the housing in the radial direction of the rotating body is formed, and the bearing device further comprises an antenna that is arranged in the through hole and receives radio waves from the communication device and transmits them to an external device, and the antenna is arranged so as to overlap the communication device in the radial direction of the rotating body.

7. The bearing device according to claim 6, wherein a sealing member made of a non-magnetic material is provided in at least a portion of the interior of said through hole.

8. A bearing device according to any one of claims 1 to 7, wherein the communication device is disposed in a region between the first bearing and a second bearing disposed in a position opposite the lid portion with the first bearing in between, and the bearing device further comprises a self-generating device disposed in a region between the first bearing and the second bearing and supplying power to the communication device.

9. A bearing device according to any one of claims 1 to 5 and 7, wherein the non-magnetic material includes resin or ceramics.

10. A bearing device according to any one of claims 1 to 9, wherein the first bearing is an angular contact ball bearing.

11. A bearing device according to any one of claims 1 to 10, wherein the rotating body is a main shaft of a machine tool.

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