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] This invention relates to a bearing device having a wireless communication function.

Background Art

[0002] In a machine including a rolling mechanism or a swing mechanism, such as a main shaft of a machine tool, a detection device such as a sensor may be attached in order to control or monitor the state of the machine. In particular, in a machine using a rolling bearing, since it is effective to detect characteristics in the vicinity of the bearing inside the machine, it is desirable to arrange various sensors such as a rotation sensor and a temperature sensor in the vicinity of the bearing inside the machine.

[0003] Conventionally, electric wires are often used to transmit data detected by sensors. However, arranging electric wires inside a machine may cause interference with other mechanisms inside the machine and deterioration of the functions of those mechanisms (for example, deterioration of dimensional accuracy and shape accuracy). In addition, the assemblability of the machine may also deteriorate, which may also be a factor in reducing productivity.

[0004] In response to the above problems, for example, Japanese Patent Application Laid-Open No. 2003-28151 (Patent Document 1) discloses a bearing device in which a wireless sensor with an antenna is attached to the outer ring of a bearing, and data detected by this wireless sensor is wirelessly transmitted to the outside by radio waves. In this bearing device, in view of the fact that the bearing and its peripheral parts (such as a housing and a lid) are made of a metal (magnetic material) that is difficult for radio waves to propagate, a space (hole or groove) is formed inside the housing located around the part where the wireless sensor is attached to facilitate the propagation of radio waves transmitted from the wireless sensor to the outside.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, in the bearing device disclosed in Japanese Patent Application Laid-Open No. 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 bearing and the like are provided inside the housing around the bearing, and when there is interference with other mechanisms, it may not be possible to form a sufficient space inside the housing. Further, if a space with a complex shape is formed inside the housing to avoid interference with other mechanisms, there is a concern that the shape accuracy of the housing may deteriorate and the cost may increase.

[0008] The present disclosure has been made to solve the above problems, and an object thereof is to provide a bearing device capable of wirelessly transmitting data to the outside without forming a space for facilitating the propagation of radio waves inside the housing around the bearing.

Means for Solving the Problems

[0009] (1) A bearing device according to the present disclosure includes a cylindrical housing that houses a rotating body therein, 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 a first bearing that rotatably supports the rotating body with respect to the housing, and an end surface in the axial direction of the housing and the outer ring A lid portion fitted to the inner diameter surface of the housing in a state of being in contact with the end surface in the axial direction thereof, and a communication device that performs wireless communication using electromagnetic waves, disposed in a region facing the lid portion with the first bearing interposed therebetween. A non-metal layer made of a non-metal material is formed on at least any one of the contact portion of the lid portion with the housing, the contact portion of the housing with the lid portion, the inner diameter portion of the lid portion, and the member disposed between the inner diameter surface of the lid portion and the outer diameter surface of the rotating body.

[0010] (2) In one aspect, the communication device is disposed in a region between a first bearing and a second bearing disposed at a position facing the lid portion with the first bearing interposed therebetween. The bearing device is disposed in the region between the first bearing and the second bearing, and further includes a self-power generation device that supplies power to the communication device.

[0011] (3) In one aspect, the non-metallic material is ceramics.

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

[0013] (5) In one aspect, the rotating body is the main shaft of a machine tool.

Advantages of the Invention

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

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[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 denoted by the same reference numerals, and the description thereof will not be repeated.

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

[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 incorporated in one end side (the right side in FIG. 1) of the 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 (the left side in FIG. 1). In the present embodiment, the shaft diameter of the main shaft 4 is set to 70 mm, and the maximum rotational speed of the main shaft 4 is set to 20,000 revolutions per minute.

[0019] The bearing device 1 includes a cylindrical housing 3 made of metal, a bearing 5 including two bearings 5a and 5b, a spacer 6 disposed between the bearing 5a and the bearing 5b, presser lids 10 and 20 made of metal, and a communication module 140.

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

[0021] The bearing 5a is a rolling bearing including a metal inner ring 5ia, a metal outer ring 5ga, a plurality of rolling elements Ta disposed between the inner ring 5ia and the outer ring 5ga, and a cage Rta. The intervals of the plurality of rolling elements Ta are held by the cage Rta.

[0022] The bearing 5b is a rolling bearing including a metal inner ring 5ib, a metal outer ring 5gb, a plurality of rolling elements Tb disposed between the inner ring 5ib and the outer ring 5gb, and a cage Rtb. The intervals of the plurality of rolling elements Tb are held by the cage Rtb.

[0023] The inner rings 5ia of the bearing 5a and the inner ring 5ib of the bearing 5b that are axially separated are fitted to the main shaft 4 in an interference fit state (press-fitted 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 - 5ib, and the outer ring spacer 6g is disposed between the outer rings 5ga - 5gb.

[0025] The bearings 5a and 5b can use angular ball bearings, deep groove ball bearings, tapered roller bearings, etc. The angular ball bearings are used in the bearing device 1 shown in Fig. 1, and the two bearings 5a and 5b are installed in a back-to-back combination (DB combination). Note that the bearing arrangement is not limited to the back-to-back combination, and for example, a face-to-face combination may be used.

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

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

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

[0029] A communication module 140 incorporating a sensor is arranged between the bearing 5a and the bearing 5b. More specifically, the communication module 140 is attached inside an outer ring spacer 6g arranged between the outer rings 5ga - 5gb. When viewed with respect to the bearing 5a, the communication module 140 is arranged in a region facing the retainer cap 10 with the bearing 5a interposed therebetween. When viewed with respect to the bearing 5b, the communication module 140 is arranged in a region facing the retainer cap 20 with the bearing 5b interposed therebetween.

[0030] FIG. 2 is a block diagram showing an example of the configuration of the communication module 140 according to the present embodiment. The communication module 140 incorporates a plurality of sensors (such as a heat flux 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) for controlling the main shaft 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 results of each sensor. Note that the communication device 141 may be wirelessly connected to each sensor and collect data indicating the detection results of each sensor wirelessly.

[0032] The communication device 141 transmits the data collected from each sensor to an external device 200 provided outside the bearing device 1 by wireless communication using electromagnetic waves. The communication device 141 conforms to, for example, the communication standard of Bluetooth (registered trademark) 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 generation device 142 is connected to the communication device 141 and self-generates electric power for driving the communication device 141. As the power generation device 142, for example, a thermoelectric element (Peltier element) that generates electricity by the Seebeck effect can be used. When electric power is required to drive each sensor, the electric power from the power generation device 142 may be supplied to that sensor.

[0034] In the present embodiment, an example in which each sensor, the communication device 141, and the power generation device 142 are modularized as a communication module 140 and arranged in the outer ring spacer 6g will be described. However, each sensor, the communication device 141, and the power generation device 142 may be arranged individually without being modularized.

[0035] <Regarding Wireless Transmission of Data> As described above, in the bearing device 1 according to the present 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 the respective sensors to the outside.

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

[0037] Also, if a space for facilitating the propagation of radio waves is formed in the radial direction inside the housing 3, problems such as interference with the refrigerant flow path of the housing 3, deterioration of the shape accuracy of the housing 3, and an increase in cost may occur.

[0038] In view of this point, in the bearing device 1 according to the present embodiment, as shown in FIG. 1, a non-metal layer 10a made of ceramics, which is a non-metal material, is provided at the contact portion of the retainer cap 10 with the housing 3 (the portion that fits with the one axial end face and the inner diameter face of the housing 3 in the retainer cap 10). Similarly, a non-metal layer 20a made of ceramics, which is a non-metal material, is provided at the contact portion of the retainer cap 20 with the housing 3 (the portion that fits with the other axial end face and the inner diameter face of the housing 3 in the retainer cap 20). Examples of the ceramics used for the non-metal layers 10a and 20a include silicon nitride, alumina, and zirconia.

[0039] Thereby, in the bearing device 1 according to the present embodiment, it is possible to wirelessly transmit the data from the communication module 140 to the outside of the bearing device 1 via the non-metal layers 10a and 20a provided at the contact portions of the retainer caps 10 and 20 with the housing 3. Thereby, it is possible to wirelessly transmit the data to the outside without forming a space for facilitating the propagation of radio waves inside the housing 3.

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

[0041] In addition, in order to appropriately wirelessly transmit the data from the communication module 140 to the outside, it is desirable that the non-metal layers 10a and 20a and the communication module 140 be disposed at positions as close as possible. FIG. 1 shows an example in which the non-metal layers 10a and 20a are provided in a part of the circumferential direction of the pressing lids 10 and 20. However, when it is difficult to align the non-metal layers 10a and 20a with the communication module 140 when fitting the pressing lids 10 and 20 to the inner diameter surface of the housing 3, the non-metal layers 10a and 20a may be provided over the entire circumferential direction of the pressing lids 10 and 20. 0 may be provided.

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

[0043] Also, the non-metal layer is not necessarily limited to being provided at both axial ends of the housing 3. That is, it may be provided with only one of the non-metal layers 10a and 20a.

[0044] [Embodiment 2] FIG. 3 is a cross-sectional view showing a schematic configuration of the bearing device 1A according to the second embodiment. In the bearing device 1A, the above-described non-metal layer is disposed not on the presser lids 10 and 20 but on the housing 3. Specifically, the bearing device 1A is obtained by changing the housing 3 and the presser lids 10 and 20 of the bearing device 1 shown in FIG. 1 above to a housing 3A and presser lids 10A and 20A, respectively. Other configurations of the bearing device 1A are the same as those of the above-described bearing device 1.

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

[0046] On the other hand, non-metal layers 3a and 3b made of a non-metal material are provided at the contact portions of the housing 3A with the presser lids 10A and 20A, respectively. Specifically, the non-metal layer 3a is provided at one axial end portion and a part of the inner diameter surface of the housing 3A, and the non-metal layer 3b is provided at the other axial end portion and a part of the inner diameter surface of the housing 3A.

[0047] Thereby, in the bearing device 1A according to the second embodiment, data from the communication module 140 can be wirelessly transmitted to the outside of the bearing device 1A via the non-metal layers 3a and 3b provided at both ends of the housing 3. Thereby, data can be wirelessly transmitted to the outside without forming a space for facilitating the propagation of radio waves inside the housing 3A.

[0048] [Embodiment 3] FIG. 4 is a cross-sectional view showing a schematic configuration of the bearing device 1B according to the third embodiment. The bearing device 1B is obtained by changing the housing 3A and the presser lid 10A of the bearing device 1A shown in FIG. 3 above to a housing 3 and a presser lid 10B, respectively, and further adding an inner ring spacer 32. Other configurations of the bearing device 1B are the same as those of the above-described bearing device 1A. Note that the housing 3 of the bearing device 1B is the same as the housing 3 of the above-described bearing device 1.

[0049] In the bearing device 1B according to the third embodiment, a labyrinth portion 30 for preventing the intrusion of foreign matter (for example, coolant liquid for machining, chips generated during machining, etc.) from the outside of the main shaft 4 is provided at the tip portion of the main shaft 4.

[0050] This labyrinth portion 30 is formed by an inner diameter portion 31 of the presser lid 10B and an inner raceway spacer 32 that is disposed between the inner diameter surface of the presser lid 10B and the outer diameter surface of the main shaft 4 and is fitted to the main shaft 4. And, as the material of the inner diameter portion 31 of the presser lid 10B and the inner raceway spacer 32 that form the labyrinth portion 30, a resin material is used. That is, the labyrinth portion 30 forms a non-metal layer.

[0051] Thereby, in the bearing device 1B according to the third embodiment, it becomes possible to wirelessly transmit the data from the communication module 140 to the outside of the bearing device 1B via the labyrinth portion 30 (non-metal layer). Thereby, even if a space for facilitating the propagation of radio waves inside the housing 3A is not formed, the data can be wirelessly transmitted to the outside.

[0052] Although FIG. 4 shows an example in which non-metal layers are formed on both the inner diameter portion 31 of the presser lid 10B and the inner raceway spacer 32 that form the labyrinth portion 30, a non-metal layer may be formed on only one of the inner diameter portion 31 of the presser lid 10B and the inner raceway spacer 32.

[0053] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is shown not by the description of the above-described embodiments but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0054] 1, 1A, 1B bearing device, 3, 3A housing, 3a, 3b, 10a, 20a non-metal 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 flux sensor, 30 labyrinth part, 31 inner diameter part, 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, the contact portion of the housing with the lid, the inner diameter portion of the lid, and a member disposed between the inner diameter surface of the lid and the outer diameter surface of the rotating body.

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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