Bearing device

Abstract

To provide a bearing device capable of transmitting data to the outside by wireless without forming a space to easily propagating electromagnetic waves into a housing around a bearing.SOLUTION: A bearing device (1) includes a housing (3) storing a main shaft (4), a bearing (5a) having an inner ring (5ia) and an outer ring (5ga) for supporting the main shaft (4) rotatably relative to the housing (3), a pressing lid (10) fitted to the inner diameter face of the housing (3) in the state of contacting the axial end face of the housing (3) and the axial end face of the outer ring (5ga), and a communication module (140) arranged in a region opposed to the pressing lid (10) across the bearing (5a) for performing wireless communication using the electromagnetic waves. In the pressing lid (10) at its portion contacting the housing (3), a non-metal layer (10a) is provided using ceramic which is a non-metal material, as a raw material.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Machines including rolling or oscillating mechanisms, such as those used in the spindles of machine tools, may be fitted with detection devices such as sensors to control or monitor the condition of the machine. In particular, in machines using rolling bearings, it is effective to detect characteristics near the bearings inside the machine, so it is desirable to place various sensors such as rotation sensors and temperature sensors near the bearings inside the machine.

[0003] In addition, 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 (e.g. reduced dimensional accuracy and reduced shape accuracy). It can also worsen the ease of assembling the machine, which can be a factor in reducing productivity.

[0004] To address the above 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 wirelessly transmitted to the outside via radio waves.In this bearing device, in view of the fact that the bearing and its peripheral parts (housing, cover, 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, in order 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] JP 2003-28151 A Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, in the bearing device disclosed in JP-A-2003-28151, a space (hole or groove) for facilitating the propagation of radio waves is formed inside the housing disposed around the bearing.

[0007] However, usually, other mechanisms for cooling the bearings are provided inside the housing around the bearings, and if there is interference with the other mechanisms, it may not be possible to form a sufficient space inside the housing. Furthermore, if a space of a complex shape is formed inside the housing to avoid interference with the other mechanisms, there is a concern that this will lead to 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 provide a bearing device that can transmit data wirelessly to the outside without having to create a space inside the housing around the bearing 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 rotor inside, a first bearing having 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 supporting the rotor rotatably relative to the housing, a lid that is fitted to the inner diameter surface of the housing while being in contact with an axial end surface of the housing and an axial end surface 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 electromagnetic waves. A non-metallic layer made of a non-metallic material is formed on at least one of the contact portion of the lid with the housing, the contact portion of the housing with the lid, the inner diameter portion of the lid, and a member arranged between the inner diameter surface of the lid and the outer diameter surface of the rotor.

[0010] (2) In one embodiment, the communication device is disposed in a region between a first bearing and a second bearing disposed at a position facing the cover with the first bearing in between. The bearing device further includes a self-power generating device disposed in the region between the first bearing and the second bearing and supplying power to the communication device.

[0011] (3) In one embodiment, the non-metallic material is a ceramic.

[0012] (4) In one embodiment, the first bearing is an angular contact ball bearing.

[0013] (5) In one embodiment, the rotating body is a spindle of a machine tool. Effect of the Invention

[0014] According to the present disclosure, it is possible to provide a bearing device that is capable of wirelessly transmitting data to the outside without forming a space inside the housing around the bearing to facilitate the propagation of radio waves. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view (part 1) showing a schematic configuration of a bearing device. [Diagram 2] FIG. 2 is a block diagram showing an example of a configuration of a communication module. [Diagram 3] FIG. 2 is a cross-sectional view (part 2) showing a schematic configuration of the bearing device. [Figure 4] FIG. 4 is a third cross-sectional view showing a schematic configuration of the bearing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0017] [Embodiment 1] FIG. 1 is a cross-sectional view showing a schematic configuration of a bearing device 1 according to the first embodiment.

[0018] The bearing device 1 shown in Fig. 1 is used, for example, as a built-in motor type spindle device of a machine tool. In this case, a motor (not shown) is built into one end side (right side in Fig. 1) of a main shaft 4 supported by the bearing device 1, and a cutting tool such as an end mill (not shown) is connected to the other end side (left side in Fig. 1). In this embodiment, the shaft diameter of the main shaft 4 is set to 70 mm, and the maximum rotation speed of the main shaft 4 is set to 20,000 rpm.

[0019] The bearing device 1 includes a metallic cylindrical housing 3, a bearing 5 including two bearings 5a and 5b, a spacer 6 arranged between the bearings 5a and 5b, metallic pressure covers 10 and 20, and a communication module 140.

[0020] The main shaft 4 is provided inside the housing 3 and is rotatably supported relative to the housing 3 by bearings 5a and 5b.

[0021] The bearing 5a is a rolling bearing including a metallic inner ring 5ia, a metallic outer ring 5ga, a plurality of rolling elements Ta disposed between the inner ring 5ia and the outer ring 5ga, and a retainer Rta. The spacing between the plurality of rolling elements Ta is maintained by the retainer Rta.

[0022] The bearing 5b is a rolling bearing including a metallic inner ring 5ib, a metallic outer ring 5gb, a plurality of rolling elements Tb disposed between the inner ring 5ib and the outer ring 5gb, and a retainer Rtb. The spacing between the plurality of rolling elements Tb is maintained by the retainer Rtb.

[0023] An inner ring 5ia of a bearing 5a and an inner ring 5ib of a bearing 5b, which are spaced apart from each other in the axial direction, are fitted onto the main shaft 4 in an interference-fit state (press-fit state).

[0024] The spacer 6 includes an inner ring spacer 6i and an outer ring spacer 6g. The inner ring spacer 6i is disposed between the inner rings 5ia and 5ib, and the outer ring spacer 6g is disposed between the outer rings 5ga and 5gb.

[0025] The bearings 5a and 5b may be angular contact ball bearings, deep groove ball bearings, tapered roller bearings, or the like. The bearing device 1 shown in Fig. 1 uses angular contact ball bearings, and the two bearings 5a and 5b are installed in a back-to-back configuration (DB configuration). The arrangement of the bearings is not limited to a back-to-back configuration, and may be, for example, a face-to-face configuration.

[0026] Here, a structure in which the main shaft 4 is supported by two bearings 5a, 5b will be described as an example, but the main shaft 4 may be supported by two or more bearings.

[0027] A coolant flow path (not shown) is formed inside the housing 3. By flowing a coolant through the coolant flow path of the housing 3, the bearings 5a and 5b can be cooled.

[0028] Each of the pressing lids 10 and 20 is an annular member for suppressing axial displacement of the housing 3 relative to the bearings 5a and 5b. The pressing lid 10 is fitted to the inner diameter surface of the housing 3 in a state of contact with an end face on one axial side of the housing 3 (the left side in FIG. 1 where a cutting tool is provided) and one axial end face of the outer ring 5ga. The pressing lid 20 is fitted to the inner diameter surface of the housing 3 in a state of contact with an end face on the other axial side of the housing 3 (the right side in FIG. 1 where a motor is provided) and one axial end face of the outer ring 5gb.

[0029] A communication module 140 with a built-in sensor is disposed between the bearing 5a and the bearing 5b. More specifically, the communication module 140 is attached inside an outer ring spacer 6g disposed between the outer rings 5ga-5gb. When the bearing 5a is used as a reference, the communication module 140 is disposed in an area facing the pressure cover 10 across the bearing 5a. When the bearing 5b is used as a reference, the communication module 140 is disposed in an area facing the pressure cover 20 across the bearing 5b.

[0030] 2 is a block diagram showing an example of the configuration of a communication module 140 according to this embodiment. The communication module 140 has a plurality of sensors (such as a heat flow sensor 11 for measuring heat flux, a temperature sensor 56 for measuring temperature, a vibration sensor 57 for measuring vibration, and a load sensor 59 for measuring preload) built in for controlling the spindle 4 and monitoring the state of the bearing device 1, a communication device 141, and a power generation device 142.

[0031] The communication device 141 is connected to each sensor by an electric wire and collects data indicating the detection result of each sensor. Note that the communication device 141 may be connected to each sensor wirelessly and collect data indicating the detection result of each sensor wirelessly.

[0032] The communication device 141 transmits data collected from each sensor by wireless communication using electromagnetic waves to an external device 200 provided outside the bearing device 1. The communication device 141 complies with, for example, the Bluetooth (registered trademark) communication standard, and can wirelessly transmit data indicating the detection results of each sensor to the external device 200 using radio waves in the 2.4 GHz frequency band.

[0033] The power generating device 142 is connected to the communication device 141 and self-generates power for driving the communication device 141. For example, a thermoelectric element (Peltier element) that generates power by the Seebeck effect can be used as the power generating device 142. When power is required to drive each sensor, the power from the power generating device 142 may be supplied to the sensor.

[0034] In this embodiment, an example is described in which the sensors, communication device 141, and power generation device 142 are modularized into a single communication module 140 and placed in the outer ring spacer 6g, but the sensors, communication device 141, and power generation device 142 may also be placed individually without being modularized.

[0035] <About wireless data transmission> As described above, in the bearing device 1 according to this embodiment, the communication module 140 is disposed between the bearing 5a and the bearing 5b, and is configured to wirelessly transmit data indicating the detection results of each sensor to the outside.

[0036] However, since the bearing 5a, and the housing 3 and the presser covers 10 and 20 around the bearing 5a are all made of metal, it is difficult to transmit radio waves from the communication module 140 to the outside of the bearing 5a and the outside of the bearing 5b.

[0037] Furthermore, if a space were formed radially inside the housing 3 to facilitate the propagation of radio waves, problems could arise such as interference with the refrigerant flow path of the housing 3, as well as deterioration of the shape accuracy of the housing 3 and increased costs.

[0038] In consideration of this, in the bearing device 1 according to this embodiment, as shown in Fig. 1, a non-metallic layer 10a made of ceramics, which is a non-metallic material, is provided on the contact portion of the pressing cover 10 with the housing 3 (the portion of the pressing cover 10 that fits with the axial end face and inner diameter surface on one side of the housing 3). Similarly, a non-metallic layer 20a made of ceramics, which is a non-metallic material, is provided on the contact portion of the pressing cover 20 with the housing 3 (the portion of the pressing cover 20 that fits with the axial end face and inner diameter surface on the other side of the housing 3). Examples of ceramics used for the non-metallic layers 10a, 20a include silicon nitride, alumina, and zirconia.

[0039] As a result, in the bearing device 1 according to this embodiment, data from the communication module 140 can be wirelessly transmitted to the outside of the bearing device 1 via the non-metallic layers 10a, 20a provided on the contact portions of the pressing covers 10, 20 with the housing 3. This makes it possible to wirelessly transmit data to the outside without forming a space inside the housing 3 to facilitate the propagation of radio waves.

[0040] Furthermore, in the bearing device 1 according to this embodiment, a power generation device 142 that self-generates power to drive the communication device 141 is disposed between the bearing 5a and the bearing 5b, in the same location as the communication device 141. Therefore, the communication device 141 can be driven without providing an electric wire outside the bearing device 1 for supplying driving power to the communication device 141.

[0041] In order to properly wirelessly transmit data from the communication module 140 to the outside, it is desirable to arrange the non-metallic layers 10a, 20a as close as possible to the communication module 140. Fig. 1 shows an example in which the non-metallic layers 10a, 20a are provided on a part of the circumferential direction of the pressing lids 10, 20, but if it is difficult to align the non-metallic layers 10a, 20a with the communication module 140 when fitting the pressing lids 10, 20 to the inner diameter surface of the housing 3, the non-metallic layers 10a, 20a may be provided over the entire circumferential direction of the pressing lids 10, 20.

[0042] The material of the non-metallic layers 10a, 20a may be any non-metallic material that allows electromagnetic waves to pass through, and is not limited to the above-mentioned ceramics. For example, the material of the non-metallic layers 10a, 20a may be a resin material such as PEEK (polyether ether ketone) or PPS (polyphenylene sulfide), a material reinforced with carbon fiber or glass fiber, glass, or rubber.

[0043] Furthermore, the non-metallic layers are not necessarily provided on both axial ends of the housing 3. In other words, only one of the non-metallic layers 10a and 20a may be provided.

[0044] [Embodiment 2] Fig. 3 is a cross-sectional view showing a schematic configuration of a bearing device 1A according to the second embodiment. In the bearing device 1A, the above-mentioned non-metallic layer is disposed on the housing 3 instead of the pressure covers 10, 20. Specifically, the bearing device 1A is obtained by changing the housing 3 and pressure covers 10, 20 of the bearing device 1 shown in Fig. 1 described above to a housing 3A and pressure covers 10A, 20A, respectively. The other configurations of the bearing device 1A are the same as those of the bearing device 1 described above.

[0045] The presser lids 10A and 20A are obtained by removing the non-metallic layers 10a and 20a from the above-mentioned presser lids 10 and 20, respectively.

[0046] Meanwhile, non-metallic layers 3a and 3b made of a non-metallic material are provided on the contact portions of the housing 3A with the retaining covers 10A and 20A, respectively. Specifically, the non-metallic layer 3a is provided on an axial end portion and part of the inner diameter surface on one side of the housing 3A, and the non-metallic layer 3b is provided on an axial end portion and part of the inner diameter surface on the other side of the housing 3A.

[0047] As a result, in the bearing device 1A according to the second embodiment, it becomes possible to wirelessly transmit data from the communication module 140 to the outside of the bearing device 1A via the non-metallic layers 3a, 3b provided on both ends of the housing 3. This makes it possible to wirelessly transmit data to the outside without forming a space inside the housing 3A to facilitate the propagation of radio waves.

[0048] [Embodiment 3] Fig. 4 is a cross-sectional view showing a schematic configuration of a bearing device 1B according to the third embodiment. In the bearing device 1B, the housing 3A and the pressing cover 10A of the bearing device 1A shown in Fig. 3 described above are changed to a housing 3 and a pressing cover 10B, respectively, and an inner ring spacer 32 is further added. The rest of the configuration of the bearing device 1B is the same as that of the above-mentioned bearing device 1A. The housing 3 of the bearing device 1B is the same as the housing 3 of the above-mentioned bearing device 1.

[0049] In the bearing device 1B according to this embodiment 3, a labyrinth portion 30 is provided at the tip portion of the spindle 4 to prevent the intrusion of foreign matter (such as coolant for machining, chips generated during machining, etc.) from outside the spindle 4.

[0050] This labyrinth portion 30 is formed by an inner diameter portion 31 of the pressing lid 10B and an inner ring spacer 32 that is disposed between the inner diameter surface of the pressing lid 10B and the outer diameter surface of the spindle 4 and is fitted to the spindle 4. A resin material is used as the material for the inner diameter portion 31 of the pressing lid 10B and the inner ring spacer 32 that form the labyrinth portion 30. In other words, the labyrinth portion 30 forms a non-metallic layer.

[0051] As a result, in the bearing device 1B according to the present embodiment 3, data from the communication module 140 can be wirelessly transmitted to the outside of the bearing device 1B via the labyrinth portion 30 (non-metallic layer). This makes it possible to wirelessly transmit data to the outside without forming a space inside the housing 3A to facilitate the propagation of radio waves.

[0052] Although Figure 4 shows an example in which a non-metallic layer is formed on both the inner diameter portion 31 and the inner ring spacer 32 of the pressure cover 10B that form the labyrinth portion 30, a non-metallic layer may be formed on only one of the inner diameter portion 31 and the inner ring spacer 32 of the pressure cover 10B.

[0053] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not by the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0054] 1, 1A, 1B bearing device, 3, 3A housing, 3a, 3b, 10a, 20a non-metallic layer, 4 main shaft, 5, 5a, 5b bearing, 5ga, 5gb outer ring, 5ia, 5ib inner ring, 6 spacer, 6g outer ring spacer, 6i, 32 inner ring spacer, 10, 10A, 10B, 20, 20A retaining cover, 11 heat flow sensor, 30 labyrinth portion, 31 inner diameter portion, 56 temperature sensor, 57 vibration sensor, 59 load sensor, 140 communication module, 141 communication device, 142 power generation device, 200 external device, Rta, Rtb cage, Ta, Tb rolling element.

Claims

1. A cylindrical housing that accommodates a rotor therein; a first bearing including an inner ring fixed to an outer diameter surface of the rotor and an outer ring fixed to an inner diameter surface of the housing, the first bearing supporting the rotor rotatably relative to the housing; a cover portion that is fitted to an inner diameter surface of the housing while 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 electromagnetic waves, A bearing device in which a non-metallic layer made of a non-metallic material is formed on at least one of the contact portion of the lid with the housing and the contact portion of the housing with the lid, for wirelessly transmitting data from the communication device to the outside of the bearing device.

2. 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 in between, The bearing device according to claim 1 , further comprising a self-powered power generating device disposed in a region between the first bearing and the second bearing and configured to supply power to the communication device.

3. 3. The bearing device according to claim 1, wherein the non-metallic material is a ceramic.

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

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

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