Bearing device

Abstract

To enable measured data to be transmitted to the outside wirelessly without forming a special 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 lid part 30; a communication device 71; and an antenna 90. The bearing 50a has an inner ring 52a and an outer ring 51a. 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. A through-hole 85 penetrating in a radial direction of the main shaft 40 is formed in the housing 25. The antenna 90 is disposed in the through hole 85 and receives and transmits electric waves from the communication device 71 to an exterior device 100. The antenna 90 is arranged so as to overlap with the communication device 71 in the radial direction of the main shaft 40.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, 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 in the radial direction of the rotating body. 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.

[0010] (2) 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.

[0011] (3) In one embodiment, the non-magnetic material includes a resin or a ceramic.

[0012] (4) 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.

[0013] (5) In one embodiment, the first bearing is an angular contact ball bearing.

[0014] (6) In one embodiment, the rotating body is a main spindle of a machine tool. [Effects of the Invention]

[0015] 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]

[0016] [Figure 1] 1 is a cross-sectional 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 second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] 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.

[0018] [Embodiment 1] FIG. 1 is a cross-sectional view showing a schematic configuration of a spindle device 1 including a bearing device 10 according to a first embodiment.

[0019] 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 (right side of 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 Fig. 1). As an example, the diameter of the spindle 40 is set to 70 mm, and the maximum rotation speed of the spindle 40 is set to 20,000 rpm.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] The rolling elements 53a and 53b are made of a metal material or a non-magnetic material such as silicon nitride.

[0024] 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.

[0025] 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.

[0026] 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 configuration (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.

[0027] 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 one axial end face (the left side in FIG. 1 ) of the housing 25 and one axial end face 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.

[0028] 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.

[0029] A communication module 70 with a built-in sensor is disposed between the bearing 50a and the bearing 50b. More specifically, the communication module 70 is attached to the outer ring spacer 61 in a state where it is exposed to the outer peripheral surface of the outer ring spacer 61 in the radial direction. In other words, the communication module 70 is disposed in a position where it comes into contact with the housing 25.

[0030] The communication module 70 will now be described in detail with reference to Fig. 2. 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 to the spindle 40. Note that the sensor 73 may include sensors other than those described above.

[0031] 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.

[0032] The communication device 71 transmits 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 communication standards such as WiFi 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. Note that while FIG. 1 shows an example in which the external device 100 is attached to the outer periphery of the outer cylinder 20, the external device 100 may also be disposed at a position separated from the spindle device 1.

[0033] The power generating 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 generating device 72. Alternatively, a generator that utilizes the rotation of a main shaft can be used as the power generating device 72. When power is required to drive a sensor, the power generating device 72 may supply power from the power generating device 72 to the corresponding sensor.

[0034] Referring again to FIG. 1 , a through hole 85 is formed in the radial direction in outer cylinder 20 and housing 25 at a position corresponding to communication module 70. When through hole 85 is viewed from the outer periphery of outer cylinder 20 along the radial direction of main shaft 40, through hole 85 overlaps so as to radially overlap communication module 70 and main shaft 40, and more preferably, overlaps so as to radially overlap communication device 71 and main shaft 40. In other words, through hole 85 is arranged so that the axial coordinate position and the circumferential coordinate position of communication module 70, and more preferably, communication device 71, and main shaft 40 are the same. In other words, when through hole 85 is viewed from the outer periphery of outer cylinder 20 along the radial direction of main shaft 40, through hole 85 overlaps communication module 70, and more preferably, overlaps communication device 71. Note that, in order not to impede cooling of bearing 50, through hole 85 is formed in a portion of housing 25 where groove portion 26 is not present.

[0035] In bearing device 10 of the first embodiment, a sealing member 80 made of a nonmagnetic material is filled in the portion of through-hole 85 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 85. 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 main shaft 40 so as to overlap in the radial direction, more preferably, communication device 71 and main shaft 40 so as to overlap in the radial direction. In other words, antenna 90 is disposed so that the axial coordinate position and circumferential coordinate position of communication module 70, 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, more preferably, communication device 71.

[0036] Antenna 90 has an overall rod-like shape, and at least a portion of it is disposed within sealing member 80 that fills 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.

[0037] 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.

[0038] By arranging such a receiving antenna 90, 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, with this configuration, it is possible to reduce the size of the device without impeding the cooling of the bearing.

[0039] 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.

[0040] <Modification> In the following modified examples, variations in the arrangement of the sealing member disposed in the through-hole will be described.

[0041] (Variation 1) Fig. 3 is a cross-sectional view showing a schematic configuration of a spindle device 1A including a bearing device 10A of Modification 1. In bearing device 10A, a sealing member 81 is disposed throughout a through-hole 85 formed in outer cylinder 20 and housing 25. Note that other configurations in Fig. 3 are similar to those of bearing device 10 of embodiment 1 shown in Fig. 1, and therefore description of those overlapping elements will not be repeated.

[0042] In bearing device 10A, sealing member 81 is disposed throughout through hole 85, not just in the portion that contacts communication module 70. This prevents clogging of through hole 85 with foreign matter such as dust or chips, and prevents corrosion or contamination of the inner circumferential surfaces of through hole 85 in housing 25 and outer cylinder 20 due to moisture seeping into through hole 85. 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 antenna 90, and / or corrosion or contamination of the outer diameter surface of antenna 90. Furthermore, compared to bearing device 10 of embodiment 1, antenna 90 can be more firmly fixed within through hole 85.

[0043] (Variation 2) 4 is a cross-sectional view showing a schematic configuration of a spindle device 1B including a bearing device 10B according to Modification 2. In the bearing device 10B, a sealing member 82 is disposed in a portion of the through-hole 85 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 85 between the sealing member 82 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 85.

[0044] 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.

[0045] [Embodiment 2] In the first embodiment, a configuration has been described in which a receiving antenna is disposed in a through hole formed in the radial direction of the housing, and radio waves from the communication module are transmitted to the outside.

[0046] In embodiment 2, a configuration is described in which a through hole is formed in a cover portion located on the end face of the housing in the main axis direction, and radio waves transmitted from the communication module are transmitted to the outside through a receiving antenna located within the through hole.

[0047] 5 is a cross-sectional view showing a schematic configuration of a spindle device 1C including a bearing device 10C according to embodiment 2. In bearing device 10C, a through-hole 86 penetrating in the axial direction is formed in cover 30, which is disposed on the tool-side end face (left side in FIG. 5) of housing 25, and a sealing member 80 is filled inside through-hole 86. At least a portion of receiving antenna 90 is disposed inside sealing member 80.

[0048] The sealing member 80 is exposed to a space formed in the axial direction between the bearing 50a and the main shaft 40 inside the housing 25. This space also communicates with the spacer 60 side across the rolling element 53a of the bearing 50a. The communication module 70 is also exposed to this space.

[0049] In the bearing device 10C, the rolling elements 53a are not made of metal but are made 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 the minute space are then received by an antenna 90 arranged in the sealing member 80 and transmitted to the external device 100.

[0050] In this manner, even in a configuration in which through hole 86 is formed in cover 30 arranged in the axial direction of spindle 40 and receiving antenna 90 is disposed within through hole 86, data measured by a sensor within housing 25 can be wirelessly transmitted to the outside. Here, the space existing in the path from communication module 70 to sealing member 80 is the space necessary to configure bearing 50a and the space for ensuring clearance to prevent contact between spindle 40 and bearing 50a. Therefore, a path for radio waves to pass through can be ensured without the need to specially form a space to facilitate propagation of radio waves to the outside.

[0051] [Aspect] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0052] (Item 1) A bearing device according to one aspect includes a cylindrical housing that accommodates a rotor, 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 rotor and an outer ring fixed to the inner diameter surface of the housing, and rotatably supports the rotor 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 located 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 in the radial direction of the rotor. The antenna is located within the through hole and receives radio waves from the communication device and transmits them to an external device. The antenna is located so as to overlap the communication device in the radial direction of the spindle.

[0053] (Item 2) In the bearing device described in item 1, a sealing member made of a non-magnetic material is provided in at least a portion of the inside of the through hole.

[0054] (Item 3) In the bearing device described in item 2, the non-magnetic material includes resin or ceramics.

[0055] (4) In the bearing device according to any one of claims 1 to 3, the communication device is disposed in a region between the first bearing and a second bearing disposed in a position facing 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, which supplies power to the communication device.

[0056] (Item 5) In the bearing device according to any one of items 1 to 4, the first bearing is an angular contact ball bearing.

[0057] (Item 6) In the bearing device according to any one of items 1 to 5, the rotating body is a main shaft of a machine tool.

[0058] 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]

[0059] 1, 1A to 1C spindle device, 10, 10A to 10C bearing device, 20 outer cylinder, 25 housing, 26 groove portion, 30 cover 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 82 sealing member, 85, 86 through hole, 90 antenna, 100 external device, 731 heat flow sensor, 732 temperature sensor, 733 vibration sensor, 734 load sensor.

Claims

1. A bearing device, 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 fitted to an inner diameter surface of the housing in a state of contacting 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, a through hole that penetrates the housing in a radial direction of the rotor, the bearing device further includes an antenna disposed in the through hole for receiving radio waves from the communication device and transmitting the radio waves to an external device; The bearing device, wherein the antenna is arranged so as to overlap with the communication device in the radial direction of the rotating body.

2. 2. The bearing device according to claim 1, wherein a sealing member made of a non-magnetic material is provided in at least a portion of the interior of the through hole.

3. The bearing device according to claim 2 , wherein the non-magnetic material includes a resin or a ceramic.

4. 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.

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

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

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