Bearing arrangement

Abstract

A bearing device (10) includes a housing (25) that houses a main shaft (40) inside, a bearing (50a), a cover portion (30) made of metal, and a communication device (71). The bearing (50a) has an inner ring (52a) and an outer ring (51a) that support the main shaft (40) so as to freely rotate relative to the housing (25). The cover portion (30) is fitted to an inner diameter surface of the housing (25) in a state of contacting 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 opposite to the cover portion (30) with the bearing (50a) interposed therebetween, and performs wireless communication using electric waves. A through-hole (85) that penetrates in an axial direction of the main shaft (40) is formed in the cover portion (30). A closing member (80) formed of a non-magnetic material is provided in the through-hole (85).

Description

Technical Field

[0001] This disclosure relates to a bearing device including a wireless communication device. Background Technology

[0002] In machines such as machine tool spindles that contain rolling or oscillating mechanisms, detection devices such as sensors are sometimes installed for machine control or condition monitoring. Especially in machines that use rolling bearings, since detection characteristics are effective near the bearings inside the machine, it is desirable to place various sensors such as vibration sensors and temperature sensors near the bearings inside the machine.

[0003] Furthermore, while traditional sensors typically transmit data via wires, placing wires inside machinery can interfere with other internal mechanisms or degrade their functionality (e.g., reduced dimensional or shape accuracy). Additionally, the machine's assemblability can worsen, potentially leading to decreased productivity.

[0004] To address the aforementioned problems, for example, Japanese Patent Application Publication No. 2003-28151 (Patent Document 1) discloses a bearing device in which a wireless sensor with an antenna is mounted on the outer ring of the bearing, and the data detected by the wireless sensor is wirelessly transmitted to the outside in the form of radio waves. In this bearing device, since the bearing and its surrounding components (such as the housing and cover) are made of metal (magnetic material) which is difficult to propagate radio waves, a space (hole or slot) is formed inside the housing surrounding the part where the wireless sensor is mounted to facilitate the propagation of radio waves transmitted from the wireless sensor to the outside.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2003-28151 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] In the bearing device disclosed in Japanese Patent Application Publication No. 2003-28151 (Patent Document 1), a space (hole or groove) for easy propagation of radio waves is formed inside the housing disposed around the bearing.

[0010] However, other mechanisms for cooling the bearing are usually located inside the housing surrounding the bearing. Interference with these other mechanisms may prevent sufficient space from being created within the housing. Furthermore, creating complex-shaped spaces within the housing to avoid interference with other mechanisms could lead to deterioration of the housing's shape accuracy or increased costs.

[0011] This disclosure is made to solve the above-mentioned technical problems, and its purpose is to enable the wireless transmission of measurement data to the outside in a bearing device including a wireless communication device, even without forming a special space inside the housing for easy propagation of radio waves.

[0012] Technical solutions adopted to solve technical problems

[0013] (1) The bearing device of the first aspect of this disclosure includes: a cylindrical housing housing a rotating body; a first bearing; a cover; 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, supporting the rotating body to rotate freely relative to the housing. The cover is formed of a metallic material. The cover is fitted into the inner diameter surface of the housing in contact with the axial end face of the housing and the axial end face of the outer ring. The communication device is disposed in the area sandwiching the first bearing and the cover opposite to it, and performs wireless communication using radio waves. At least one through hole is formed in the cover, extending along the axial direction of the rotating body. A sealing member made of a non-magnetic material is provided in the at least one through hole.

[0014] (2) In one embodiment, when the cover is viewed from the axial direction of the rotating body, at least one through hole is formed at a position at a first distance from the center of the rotation axis of the rotating body. The first circumferential dimension of each through hole relative to the center of the rotation axis is more than 1 / 10 of the wavelength of the radio wave used in the wireless communication of the communication device. The sum of the first dimensions of at least one through hole is less than half the length of the circumference with the first distance as the radius.

[0015] (3) In one embodiment, when viewed in the cross section passing through each through hole and along the axis of rotation of the rotating body, the through hole has a crank shape.

[0016] (4) In one embodiment, when the cover is viewed from the axial direction of the rotating body, the closing member overlaps with at least a portion of the outer ring.

[0017] (5) In one embodiment, the communication device is capable of communicating with an external device wirelessly. The bearing device also includes an antenna, at least a portion of which is disposed within an enclosed member. The antenna receives radio waves from the communication device and transmits them to the external device.

[0018] (6) The bearing device of the second aspect of this disclosure includes: a cylindrical housing housing a rotating body; a first bearing; a cover; 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, supporting the rotating body to rotate freely relative to the housing. The cover is fitted into the inner diameter surface of the housing in contact with the axial end face of the housing and the axial end face of the outer ring. The communication device is disposed in the area sandwiching the first bearing and the cover opposite to it, and performs wireless communication using radio waves. A through hole is formed in the housing, extending along the radial direction of the rotating body. The antenna is disposed in the through hole, receiving radio waves from the communication device and transmitting them to an external device. The antenna is disposed in a manner that overlaps with the communication device in the radial direction of the main shaft.

[0019] (7) In one embodiment, at least a portion of the interior of the through hole is provided with a sealing member made of a non-magnetic material.

[0020] (8) In one embodiment, the communication device is disposed in the region between the first bearing and the second bearing, the second bearing being disposed at a position sandwiching the first bearing and opposite the cover. The bearing assembly further includes a self-generating device disposed in the region between the first bearing and the second bearing, which supplies power to the communication device.

[0021] (9) In one embodiment, the non-magnetic material comprises resin or ceramic.

[0022] (10) In one embodiment, the first bearing is an angular contact ball bearing.

[0023] (11) In one embodiment, the rotating body is the spindle of the machine tool.

[0024] Invention Effects

[0025] According to this disclosure, in a bearing device including a wireless communication device, measurement data can be wirelessly transmitted to the outside even without forming a special space inside the housing for easy propagation of radio waves. Attached Figure Description

[0026] Figure 1 These are cross-sectional and side views showing the general structure of the spindle assembly including the bearing device of Embodiment 1.

[0027] Figure 2 This is a block diagram illustrating an example of the structure of a communication module.

[0028] Figure 3 This is a cross-sectional view showing the general structure of the spindle assembly, including the bearing assembly of Variation Example 1.

[0029] Figure 4This is a cross-sectional view showing the general structure of the spindle assembly, including the bearing assembly of Variation 2.

[0030] Figure 5 This is a cross-sectional view showing the general structure of the spindle assembly, including the bearing assembly of Variation 3.

[0031] Figure 6 This is a cross-sectional view showing the general structure of the spindle assembly including the bearing device of Embodiment 2.

[0032] Figure 7 This is a cross-sectional view showing the general structure of the spindle assembly including the bearing device of Embodiment 3.

[0033] Figure 8 This is a cross-sectional view showing the general structure of the spindle assembly including the bearing device of Embodiment 4.

[0034] Figure 9 This is a cross-sectional view showing the general structure of the spindle assembly, including the bearing assembly of variant four.

[0035] Figure 10 This is a cross-sectional view showing the general structure of the spindle assembly, including the bearing assembly of variant five. Detailed Implementation

[0036] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent parts are labeled with the same reference numerals in the drawings, and their descriptions will not be repeated.

[0037] [Implementation Method 1]

[0038] Figure 1 These are side views (left figure a) and cross-sectional views (right figure b) of the main shaft assembly 1, which includes the bearing assembly 10 of Embodiment 1.

[0039] Figure 1 The spindle assembly 1 shown is used, for example, as a spindle assembly with a built-in motor in a machine tool. In this case, on one end side of the spindle 40 supported by the spindle assembly 1 for machine tool spindles ( Figure 1 The right side of the sectional view contains a motor (not shown), and the other end ( Figure 1 (On the left side of the sectional view) are connected cutting tools such as end mills, not shown. As an example, the spindle diameter of spindle 40 is set to 70 mm, and the maximum speed of spindle 40 is set to 20,000 rpm.

[0040] The spindle assembly 1 includes a bearing assembly 10. The bearing assembly 10 includes: a bearing 50 comprising two bearings 50a and 50b; and a spacer ring 60 disposed between the bearings 50a and 50b. The spindle 40 is disposed inside a cylindrical housing 25 embedded in the inner diameter portion of the outer cylinder 20 and is supported by the bearings 50a and 50b for free rotation. The housing 25 has a groove 26 that functions as a cooling medium flow path. By allowing the cooling medium to flow between the outer cylinder 20 and the housing 25, the bearings 50a and 50b can be cooled.

[0041] Bearing 50a is a rolling bearing comprising 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 retainer 54a. The plurality of rolling elements 53a are spaced apart by the retainer 54a.

[0042] Bearing 50b is a rolling bearing comprising 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 retainer 54b. The plurality of rolling elements 53b are spaced apart by the retainer 54b.

[0043] Multiple rolling elements 53a, 53b are formed, for example, from non-magnetic materials such as silicon nitride.

[0044] On the spindle 40, the inner rings 52a of bearing 50a and 52b of bearing 50b, which are axially separated, are fitted together in an interference fit (press-fit state).

[0045] Spacer ring 60 includes an outer spacer ring 61 and an inner spacer ring 62. The outer spacer ring 61 is disposed between outer rings 51a and 51b. The inner spacer ring 62 is disposed between inner rings 52a and 52b.

[0046] Bearings 50a and 50b can be made of angular contact ball bearings, deep groove ball bearings, tapered roller bearings, or cylindrical roller bearings, etc. Figure 1 The bearing assembly 10 shown uses angular contact ball bearings, with two bearings 50a and 50b arranged in a back-to-back (DB) configuration. However, the bearing arrangement is not limited to a back-to-back configuration; for example, a face-to-face configuration is also possible. This specification describes a structure where two bearings 50a and 50b support the spindle 40 as an example, but a structure where more than two bearings support the spindle 40 is also possible.

[0047] The cover 30 is an annular member used to suppress axial displacement of the housing 25 relative to the bearing 50a. The cover 30 is located on the side opposite to the axial direction of the housing 25. Figure 1The cover 30 is fitted into the inner diameter surface of the housing 25 with its end face (left side of Figure b) in contact with the axial end face of the outer ring 51a. In order to support the load from the housing 25 and the bearing 50, the cover 30 is formed of a metal material capable of withstanding the load.

[0048] A through hole 85 is formed in the cover portion 30, extending along the rotation axis of the main shaft 40. Viewed from the rotation axis of the main shaft 40, the through hole 85 is formed in an arc shape at a distance R1 from the center SP of the rotation axis, and a sealing member 80 made of a non-magnetic material such as resin or ceramic is disposed inside it. The sealing member 80 can be any non-metallic material that can transmit electromagnetic waves, such as resin materials like PEEK (polyetheretherketone) or PPS (polyphenylene sulfide), carbon fiber or glass fiber reinforced materials, or glass or rubber. The material of the sealing member 80 is preferably selected considering compatibility with the metal cover portion (differences in expansion / contraction due to temperature changes, thermal expansion rate), strength assurance, cost, and flowability.

[0049] like Figure 1 As shown in the cross-sectional view (Right Figure b), the through hole 85 is formed along the inner diameter surface of the housing 25, and the sealing member 80 reaches the outer ring 51a of the bearing 50a. In other words, when viewed from the rotation axis direction of the spindle 40, the sealing member 80 at least partially overlaps with the outer ring 51a.

[0050] The inner diameter portion of the cover 30 has a shape that engages with a recess formed on the spindle 40 when spaced apart from it. By forming such a shape, a so-called "labyrinth structure" with narrow intersecting spaces is formed between the spindle 40 and the cover 30. With this labyrinth structure, it is possible to prevent chips generated during cutting and coolant used during cutting from entering the spindle while the spindle 40 is rotated relative to the fixed cover 30.

[0051] A communication module 70 with an internal sensor is disposed between bearings 50a and 50b. More specifically, the communication module 70 is mounted on the outer ring spacer 61 with its end face exposed on the axial side of the bearing 50a (cutting tool side). Alternatively, the same communication module 70 may also be provided on the axial end face of the outer ring spacer 61 on the bearing 50b (motor side).

[0052] Figure 2 This is a block diagram illustrating an example of the structure of the communication module 70. The communication module 70 includes a communication device 71, a power generation device 72, and at least one sensor 73 for controlling the spindle 40 and / or monitoring the condition of the bearing assembly 10. Figure 2In the example, sensor 73 includes a heat flow sensor 731 for measuring the heat flow stream, a temperature sensor 732 for measuring temperature, a vibration sensor 733 for measuring vibration, and a load sensor 734 for measuring bearing preload, cutting load, and / or load transmitted from spindle 40. Furthermore, sensor 73 may also include sensors other than those described above.

[0053] The communication device 71 is connected to each sensor via a wired connection to collect data representing the detection results of each sensor. Alternatively, the communication device 71 can also be connected to each sensor wirelessly to collect data representing the detection results of each sensor wirelessly.

[0054] The communication device 71 transmits the data collected by each sensor to an external device 100 located outside the bearing device 10 via wireless communication using radio waves. In Embodiment 1, the communication device 71 conforms to communication standards such as WiFi or Bluetooth (registered trademark) and uses radio waves in the 2.4 GHz band to wirelessly transmit data representing the detection results of each sensor to the external device 100.

[0055] The power generation device 72 is connected to the communication device 71 to generate electricity to drive the communication device 71. For example, a thermoelectric element (Peltier element) that generates electricity through the Seebeck effect can be used as the power generation device 72. Furthermore, when electricity is needed to drive a sensor, power can also be supplied from the power generation device 72 to the corresponding sensor.

[0056] Here, the external device 100 for receiving data from the communication module 70 is pre-configured on the axial outer side of the bearing 50a (in Figure 1 (See Figure b on the right, which shows the left side of bearing 50a, i.e., the tool side). Therefore, bearing 50a exists between communication device 71 and external device 100. As described above, the rolling element 53a of bearing 50a is not made of metal, but is formed of a non-magnetic material such as silicon nitride (Si3N4). Therefore, radio waves radiated from communication module 70 pass through the rolling element 53a formed of silicon nitride and reach the tiny space between bearing 50a and cover 30. Then, the radio waves reaching this tiny space are radiated to the outside of bearing device 10 via the non-magnetic material sealing member 80.

[0057] The arc length L1 (first dimension) of the through hole 85 is set to λ / 10 or more when the wavelength of the radio wave transmitted from the communication module 70 is set to λ. As a result, the radio wave transmitted by the communication module 70 can pass through the closed member 80 disposed within the through hole 85.

[0058] Furthermore, when the cover portion 30 has multiple through holes 85, the total arc length L1 is set to be less than half the length of the circumference of a circle with a radius of R1 (first distance) from the rotation axis center SP of the main shaft 40. As described above, the cover portion 30 needs to support the load from the housing 25 and the bearing 50. Therefore, by setting the total arc length L1 of the through holes 85 to be less than half the circumference length, the desired load-bearing capacity can be maintained.

[0059] In recent years, the machining of difficult-to-machine materials such as titanium and / or the use of high-speed, heavy-duty cutting to improve productivity have increased in machine tools, leading to a rise in wet cutting processes using high-pressure coolants. Therefore, to prevent coolant from seeping into the spindle 40, the labyrinth structure between the cover 30 and the spindle 40 is becoming increasingly complex and narrower. This makes it difficult for electromagnetic waves to pass through the gaps in the labyrinth structure.

[0060] Furthermore, to ensure the path of the radio waves, a structure in which a non-magnetic material component is disposed between the axial end face of the housing 25 and the cover 30 can be considered. However, since the load needs to be supported through the contact surface between the cover 30 and the housing 25, the dimensional accuracy and deformation of the non-magnetic material component disposed between the housing 25 and the cover 30 may have a significant impact on the magnitude of the preload imparted to the bearing 50, or on the variation of that preload during operation.

[0061] In the bearing device 10 of Embodiment 1, a through hole 85 extending axially is formed in the cover portion 30, and a sealing member 80 made of non-magnetic material is provided in the through hole 85. With this structure, the path of radio waves can be ensured without compromising the axial load-bearing capacity of the cover portion 30. Furthermore, the space existing along the path from the communication module 70 to the sealing member 80 is the space required to construct the bearing 50a, and also the space to ensure a gap to prevent contact between the spindle 40 and the bearing 50a. Therefore, in the bearing device 10 of Embodiment 1, the path of radio waves can be ensured without the need to specially form a space that facilitates the propagation of radio waves to the outside.

[0062] In Embodiment 1, "spindle 40" corresponds to "rotating body" in this disclosure. In Embodiment 1, "bearing 50a" and "bearing 50b" correspond to "first bearing" and "second bearing" in this disclosure, respectively.

[0063] <Variation Example>

[0064] The following variations illustrate the arrangement of the through holes formed in the cover.

[0065] (Variation Example 1)

[0066] In Embodiment 1, a structure in which the cross-section of the through hole formed in the cover is linear along the axis of rotation was described. In Modification 1, an example of a structure in which the through hole is curved inside the cover was described.

[0067] Figure 3 This is a cross-sectional view showing the general structure of the spindle assembly 1A, including the bearing assembly 10A of the modified example. The through-hole 85A of the cover portion 30A in the bearing assembly 10A has a crank shape when viewed in cross-section along the axis of rotation passing through the through-hole 85A. Furthermore, a sealing member 80 is provided within the through-hole 85A. Even with this through-hole shape, electromagnetic waves can be radiated to the outside via the sealing member 80.

[0068] By setting the through hole 85A to a crank shape, the sealing member 80 can be prevented from falling out of the through hole when the sealing member 80 is configured or when the cover 30A is installed on the housing 25.

[0069] (Variation Example 2)

[0070] In the second variation, a structure is described that makes the position of the through hole different from the center of the rotation axis of the cover.

[0071] Figure 4 This is a cross-sectional view showing the general structure of the spindle assembly 1B, including the bearing assembly 10B of Variation 2. The through hole 85B of the cover portion 30B in the bearing assembly 10B is formed at a position slightly offset towards the center of the rotation axis compared to the through hole 85 in Embodiment 1, and extends through the labyrinth structure. Therefore, the outer ring 51a of the bearing 50a does not contact the closing member 80 disposed in the through hole 85B, but contacts the metal portion of the cover portion 30B.

[0072] Generally speaking, the metal material of the cover 30B is superior in terms of load-bearing capacity than the material forming the closing member 80. Therefore, by adopting a structure like the cover 30B with the bearing device 10B, the axial load-bearing capacity of the cover 30B can be improved.

[0073] (Example 3)

[0074] In variation example three, the structure in which the shape of the inner diameter portion of the cover is changed is explained.

[0075] Figure 5 This is a cross-sectional view showing the general structure of the spindle assembly 1C, including the bearing assembly 10C of Variation 3. In the bearing assembly 10C, the through hole 85 in the cover 30C is located at the same position as in Embodiment 1. However, the cover 30C has a stepped structure with a protrusion 35 for supporting the closing member 80, located more inwardly than the closing member 80.

[0076] In the bearing assembly 10 of Embodiment 1, a large portion of the inner surface of the sealing member 80 is exposed within the space of the bearing assembly. Therefore, when the cover 30 is installed on the housing 25, if an axial compressive force is applied to the sealing member 80 due to its contact with the outer ring 51a, the sealing member 80 may buckle or bend, partially protruding in the spatial direction (i.e., the rotational axis side). This could lead to contact between the sealing member 80 and the main shaft 40, or the sealing member 80 may peel off, causing a malfunction.

[0077] On the other hand, in the bearing assembly 10C of Modified Example 3, since the sealing member 80 is supported by the protrusion 35 which is further inward than the sealing member 80, deformation of the sealing member 80 can be prevented when the cover 30 is installed on the housing 25. Therefore, it is possible to suppress the failure of the bearing assembly 10C.

[0078] [Implementation Method Two]

[0079] In Embodiment 2, the structure in which the antenna 90 for receiving radio waves from the communication module 70 is arranged in the enclosure member 80 will be described.

[0080] Figure 6 This is a cross-sectional view showing the general structure of the spindle assembly 1D including the bearing assembly 10D of Embodiment 2. The bearing assembly 10D is a structure formed by adding an antenna 90 to the structure of the bearing assembly 10 of Embodiment 1.

[0081] The antenna 90 has an overall rod shape, with at least a portion disposed within the closed member 80 located in the through hole 85. The antenna 90 can be a monopole antenna, or, in the case of using higher frequency millimeter waves or higher frequency radio waves, it can also be a structure in which a plate-shaped patch antenna is mounted on the tip of the rod-shaped member.

[0082] Antenna 90 can be connected to external device 100 via a cable in a wired manner, or it can further communicate with external device 100 wirelessly. In the case of wireless communication, a relay device (not shown) can be further provided for wirelessly transmitting signals received from communication module 70 through antenna 90.

[0083] By configuring such a receiving antenna 90, the signal sent from the communication module 70 can be transmitted to the external device 100 more reliably.

[0084] [Implementation Method 3]

[0085] In Embodiment 1 and Embodiment 2, the following structure is described: a through hole is formed on the cover portion disposed 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.

[0086] In Embodiment 3, a structure that radiates radio waves from the communication module to the outside through a through hole formed in the radial direction of the housing will be described.

[0087] Figure 7 This is a cross-sectional view showing the general structure of the spindle assembly 1E, including the bearing assembly 10E according to Embodiment 3. In the bearing assembly 10E, the cover portion 30 does not have a through hole. Instead, a through hole 85E is formed radially in the housing 25 and the outer cylinder 20, and a non-magnetic sealing member 80E is disposed inside the through hole 85E. Furthermore, to avoid hindering the cooling of the bearing 50, the through hole 85E is formed in the portion of the housing 25 without the groove 26.

[0088] Furthermore, the communication module 70 is configured to protrude from the radial outer peripheral surface of the outer spacer ring 61 and is positioned on the outer peripheral surface of the outer spacer ring 61 at a location overlapping with the through hole 85E. This structure allows radio waves from the communication module 70 to propagate through the closed member 80E within the through hole 85E and radiate outwards.

[0089] With this structure, measurement data can be transmitted wirelessly to the outside without creating a special space inside the casing for easy propagation of radio waves.

[0090] Furthermore, the bearing device 10E in Embodiment 3 can also, similarly to the bearing device 10D in Embodiment 2, have a receiving antenna disposed within the closed member 80E of the through hole 85E. Additionally, in the case of the bearing device 10E, the plurality of rolling elements 53a and 53b can also be formed of a metallic material.

[0091] [Implementation Method Four]

[0092] In Embodiment 4 and the following variations 3 and 4, a structure in which a through hole is formed in the radial direction of the housing and an antenna is arranged in the through hole, similar to Embodiment 3, will be described.

[0093] Figure 8 This is a cross-sectional view showing the general structure of the spindle assembly 1F, including the bearing assembly 10F of Embodiment 4.

[0094] Reference Figure 8In the bearing assembly 10F, the outer cylinder 20 and the housing 25 have through holes 86 formed radially at positions corresponding to the communication module 70. When the through hole 86 is viewed from the outer periphery of the outer cylinder 20 along the radial direction of the main shaft 40, the through hole 86 overlaps with the communication module 70 in the radial direction of the main shaft 40, and more preferably, overlaps with the communication device 71 in the radial direction of the main shaft 40. That is, the through hole 86 is arranged such that its axial coordinate position and circumferential coordinate position are the same as those of the communication module 70, and more preferably, the communication device 71. In other words, when the through hole 86 is viewed from the outer periphery of the outer cylinder 20 along the radial direction of the main shaft 40, the through hole 86 overlaps with the communication module 70, and more preferably, overlaps with the communication device 71. Furthermore, to avoid hindering the cooling of the bearing 50, the through hole 86 is formed in the portion of the housing 25 without the groove 26.

[0095] In the bearing device 10F of Embodiment 4, the portion of the through hole 86 that contacts the communication module 70 is filled with a non-magnetic sealing member 81. Furthermore, an antenna 90 for receiving signals transmitted from the communication device 71 included in the communication module 70 is disposed inside the through hole 86. When the antenna 90 is viewed from the outer periphery of the outer cylinder 20 along the radial direction of the main axis 40, the antenna 90 overlaps with the communication module 70 in the radial direction of the main axis 40, and more preferably overlaps with the communication device 71 in the radial direction of the main axis 40. That is, the antenna 90 is arranged such that its axial coordinate position and circumferential coordinate position are the same as those of the communication module 70, and more preferably, the communication device 71. In other words, when the antenna 90 is viewed from the outer periphery of the outer cylinder 20 along the radial direction of the main axis 40, the antenna 90 overlaps with the communication module 70, and more preferably with the communication device 71.

[0096] The antenna 90 has an overall rod shape, with at least a portion disposed within the closed member 81 that fills the through-hole 86. The antenna 90 can be a monopole antenna, or, in the case of using higher frequency millimeter waves or higher frequency radio waves, it can also be a structure in which a plate-shaped patch antenna is mounted on the tip of the rod-shaped member.

[0097] Antenna 90 can be connected to external device 100 via a cable in a wired manner, or it can further communicate with external device 100 wirelessly. In the case of communicating with external device 100 wirelessly, a relay device (not shown) can be further provided for wirelessly transmitting signals received by antenna 90 from communication device 71.

[0098] By configuring the receiving antenna 90 in this way, the signal transmitted from the communication module 70 can be transmitted to the external device 100 more reliably. In particular, by adopting a structure in which a portion of the through hole 85 formed on the housing 25 contacts the communication module 70, it is unnecessary to form a special space inside the housing for easy propagation of radio waves. Therefore, this structure enables miniaturization of the device without hindering bearing cooling.

[0099] In Embodiment 4, "spindle 40" corresponds to "rotating body" in this disclosure. In Embodiment 4, "bearing 50a" and "bearing 50b" correspond to "first bearing" and "second bearing" in this disclosure.

[0100] <Variation Example>

[0101] In the following variations four and five, variations in the arrangement of the closing member disposed within the through hole will be described.

[0102] (Example 4)

[0103] Figure 9 This is a cross-sectional view showing the general structure of the spindle assembly 1G, including the bearing assembly 10G of variant four. In the bearing assembly 10G, the sealing member 82 is disposed integrally with the through hole 86 formed in the outer cylinder 20 and the housing 25. Furthermore, Figure 9 Other structures in Figure 8 The bearing device 10F of Embodiment 4 shown is similar, so the description of its repetitive elements will not be repeated.

[0104] In the bearing assembly 10G, a sealing member 82 is provided not only in the portion contacting the communication module 70 but also throughout the through hole 86. This prevents blockage of the through hole 86 due to foreign matter such as dust or chips, and prevents corrosion or contamination of the inner circumferential surface of the through hole 85 of the housing 25 and the outer cylinder 20 due to moisture infiltration into the through hole 86. Furthermore, it prevents communication quality degradation and / or corrosion or contamination of the outer diameter surface of the antenna 90 due to metallic foreign matter adhering to it. Moreover, compared to the bearing assembly 10 of Embodiment 1, the fixation of the antenna 90 inside the through hole 86 is strengthened.

[0105] (Variation Example 5)

[0106] Figure 10This is a cross-sectional view showing the schematic structure of the spindle assembly 1H, including the bearing assembly 10H of Modified Example 5. In the bearing assembly 10H, a sealing member 83 is disposed in a portion of the through hole 86 near 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 in such a structure, it is possible to prevent foreign matter such as dust or chips, as well as moisture, from entering the through hole 86.

[0107] Furthermore, cooling water flows within the housing 25 to cool the bearing 50 and spacer ring 60 within the housing 25. Therefore, from the viewpoint of improving cooling efficiency, it is preferable to have the housing 25 in direct contact with these components as much as possible. In the bearing assembly 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 impact of the space formation on cooling efficiency can be limited to a finite range.

[0108] It should be considered that the embodiments disclosed herein are illustrative rather than restrictive in all respects. The scope of the invention is defined by the claims rather than the description of the above embodiments, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0109] Explanation of reference numerals in the attached figures

[0110] 1. 1A~1H Spindle assembly; 10. 10A~10H Bearing assembly; 20 Outer cylinder; 25 Housing; 26 Groove; 30. 30A~30C Cover; 35 Protrusion; 40 Spindle; 50. 50a. 50b Bearing; 51a. 51b Outer ring; 52a. 52b Inner ring; 53a. 53b Rolling element; 54a. 54b Retainer; 60 Spacer ring; 61 Outer spacer ring; 62 Inner spacer ring; 70 Communication module; 71 Communication device; 72 Power generation device; 73 Sensor; 80~83. 80E Enclosure component; 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, characterized in that, include: A cylindrical shell that houses a rotating body; A 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, supporting the rotating body to rotate freely relative to the housing; A cover, formed of a metallic material, fits into the inner diameter surface of the housing while in contact with the axial end face of the housing and the axial end face of the outer ring; and A communication device, positioned in the area sandwiching the first bearing and opposite the cover, performs wireless communication using radio waves. At least one through hole is formed in the cover portion, extending along the axial direction of the rotating body. A closed member made of non-magnetic material is provided in the at least one through hole.

2. The bearing device according to claim 1, characterized in that, When the cover is viewed from the axial direction of the rotating body, the at least one through hole is formed at a position at a first distance from the center of the rotation axis of the rotating body. The first circumferential dimension of each through hole relative to the center of the rotation axis is more than 1 / 10 of the wavelength of the radio wave used in the wireless communication of the communication device. The sum of the first dimensions in the at least one through hole is less than half the length of the circumference with the first distance as the radius.

3. The bearing device according to claim 2, characterized in that, When observing the cross-section passing through each through hole and along the axis of rotation of the rotating body, the through hole has a crank shape.

4. The bearing device according to any one of claims 1 to 3, characterized in that, When the cover is viewed from the axial direction of the rotating body, the closing member overlaps with at least a portion of the outer ring.

5. The bearing device according to any one of claims 1 to 4, characterized in that, The communication device is capable of communicating with external devices wirelessly. The bearing assembly also includes an antenna, at least a portion of which is disposed within the enclosed member, to receive radio waves from the communication device and transmit them to the external device.

6. A bearing device, characterized in that, include: A cylindrical shell that houses a rotating body; A 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, supporting the rotating body to rotate freely relative to the housing; A cover portion, which fits into the inner diameter surface of the housing in contact with the axial end face of the housing and the axial end face of the outer ring; and A communication device is disposed in the area sandwiching the first bearing and the cover, and performs wireless communication using radio waves. A through hole is formed in the housing, extending along the radial direction of the rotating body. The bearing assembly further includes an antenna disposed within the through hole and used to receive radio waves from the communication device and transmit them to an external device. The antenna is configured to overlap with the communication device in the radial direction of the rotating body.

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

8. The bearing device according to any one of claims 1 to 7, characterized in that, The communication device is disposed in the area between the first bearing and the second bearing, and the second bearing is disposed in a position that sandwiches the first bearing and is opposite to the cover. The bearing assembly also includes a self-generating device disposed in the area between the first bearing and the second bearing, which supplies power to the communication device.

9. The bearing device according to any one of claims 1 to 5 and 7, characterized in that, The non-magnetic material includes resin or ceramic.

10. The bearing device according to any one of claims 1 to 9, characterized in that, The first bearing is an angular contact ball bearing.

11. The bearing device according to any one of claims 1 to 10, characterized in that, The rotating body is the spindle of the machine tool.

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