Bearing device, spindle device, and electric vertical take-off and landing aircraft

Abstract

To provide a small-sized bearing device capable of accurately measuring a temperature rise or acceleration with rotations of a bearing.SOLUTION: A bearing device 1 comprises: an outer ring 2; an inner ring 3; a plurality of rolling elements 4; an outer annulus 7; a magnetic ring 8; a cylindrical heat insulation part 11 of which heat conductivity is low and which consists of a non-metal insulator and includes a partition wall 11a extending in a radial direction; and a stator 9 fixed at an opposite side of a bearing B with the partition wall 11a interposed therebetween. The magnetic ring 8 is disposed so as to face the stator 9, and the stator 9 and the magnetic ring 8 constitute a generator G. The bearing device 1 further comprises a circuit board 10 which is fixed in a space closer to the bearing B side than the partition wall 11a. The circuit board 10 includes a power supply circuit 16 which creates a DC power source by performing rectification processing on power generated by the generator G, at least one sensor 17 for detecting a state of the bearing B, and a wireless communication circuit 20 for transmitting output of the at least one sensor 17 to an outside wirelessly.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a bearing assembly, a spindle assembly, and an electric vertical take-off and landing aircraft. [Background technology]

[0002] It is known to combine a bearing with a generator and use it as a power source for sensors, wireless communication, etc. A bearing with a wireless sensor disclosed in JP 2006-170624 A (Patent Document 1) comprises a rolling bearing, a rotation sensor that also functions as a generator, and a wireless transmission circuit that wirelessly transmits the output of the rotation sensor.

[0003] The rotation sensor is composed of a magnetic encoder and a magnetic ring with a coil housed inside, and the magnetic ring functions as a stator of the rotation sensor for the generator. The rotation sensor is also used with a claw-pole type generator.

[0004] The magnetic ring containing the coil is fitted to the inner diameter surface of the outer member and faces the magnetic encoder. A cover that covers the inboard end of the wheel bearing is attached to the outer member, and an annular wireless transmitting means for wirelessly transmitting the output of the rotation sensor is installed in a stepped portion extending from the flange portion of the outer diameter surface of the cover to the small diameter portion.

[0005] The bearing with wireless sensor disclosed in JP 2019-7580 A (Patent Document 2) is composed of a bearing body, a sensor, a power generation component, a wireless processing circuit, a power supply circuit, a cover, and a cooling fan formed in the cover.

[0006] In the bearing with wireless sensor of Patent Document 2, when the inner ring of the bearing body rotates, the temperature of the bearing rises due to heat generated from the raceway grooves of the outer and inner rings, heat generated from the power generation part (coil) as a result of power generation, and a rise in temperature in the usage environment, etc. In the bearing with wireless sensor of Patent Document 2, heat dissipation fins are provided on the outside of the cover to prevent the wireless circuit, power supply circuit, etc. attached to the cover from breaking down due to the effects of heat. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2006-170624 A [Patent Document 2] JP 2019-7580 A Summary of the Invention [Problem to be solved by the invention]

[0008] The magnetic ring described in Patent Document 1 is directly fitted to the inner diameter surface of the outer member (outer ring) of the wheel support bearing, so heat generated by iron loss in the magnetic ring during power generation is directly transferred to the outer member, causing the temperature of the wheel support bearing to rise. In the bearing with wireless sensor of Patent Document 1, if a temperature sensor is placed on the outer member to monitor the temperature rise caused by the rotation of the wheel support bearing, it is difficult to accurately measure the temperature of the outer member. In the bearing with wireless sensor of Patent Document 1, when measuring the acceleration of the wheel support bearing, it is difficult to place an acceleration sensor close to the wheel support bearing because of the presence of the outer member.

[0009] The bearing with wireless sensor described in Patent Document 2 has a cover formed by press molding of a metal plate fixed to a groove provided on the outer periphery of the outer ring, and a circuit board with a sensor mounted thereon and a first power generation unit (yoke, magnet, and coil) are mounted inside the cover. For this reason, heat generated with power generation is conducted to the temperature sensor mounted on the circuit board and to the bearing. With the bearing with wireless sensor described in Patent Document 2, it is difficult for the temperature sensor to detect only the heat generated from the raceway grooves of the outer ring and inner ring, making it difficult to properly determine whether or not there is an abnormality in the bearing.

[0010] In the bearing with a wireless sensor described in Patent Document 2, a rectangular recess is formed on the outer surface of the cover and a transmitting antenna is disposed in the recess, which makes the cover shape complicated and increases the assembly labor.In the bearing with a wireless sensor described in Patent Document 2, cooling fins are formed separately from the cover, which increases the number of parts.

[0011] The present disclosure has been made to solve the above-mentioned problems, and has an objective to provide a small bearing device, a spindle device, and an electric vertical take-off and landing aircraft that are capable of accurately measuring the temperature rise that accompanies the rotation of a bearing. [Means for solving the problem]

[0012] The present disclosure relates to a bearing device including a bearing. The bearing device includes an outer ring, an inner ring, a plurality of rolling elements disposed between the outer ring and the inner ring, a fixed member fixed to one of the outer ring and the inner ring, a magnetic ring fixed to the other of the outer ring and the inner ring so as to face the fixed member, a cylindrical heat insulating part fixed to the fixed member and made of a nonmetallic insulator with low thermal conductivity and having a partition wall extending in the radial direction, and a stator fixed to the opposite side of the bearing across the partition wall. The magnetic ring is disposed to face the stator. The stator and the magnetic ring constitute a generator. The bearing device further includes a circuit board fixed in a space on the bearing side relative to the partition wall. The circuit board includes a power supply circuit that rectifies the power generated by the generator to create a direct current power supply, at least one sensor that detects the state of the bearing, and a wireless communication circuit that wirelessly transmits the output of the at least one sensor to the outside. Effect of the Invention

[0013] According to the present disclosure, it is possible to provide a small-sized bearing device that is capable of accurately measuring the temperature rise that accompanies the rotation of a bearing. [Brief description of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view of a bearing device according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing a schematic configuration of a generator. [Diagram 3] FIG. 13 is a diagram showing a state in which two magnetic ring members of the same shape are arranged opposite each other. [Figure 4] FIG. 13 is a diagram showing a state in which two magnetic ring members are fitted together. [Diagram 5] FIG. 2 is a cross-sectional view of a bearing device according to a first modified example of the first embodiment. [Figure 6] 6 is a cross-sectional view taken along line VI-VI of FIG. 5. [Figure 7] FIG. 2 is a perspective view illustrating the shape of a stator. [Figure 8] FIG. 11 is a cross-sectional view showing a schematic configuration of a second modified example of the first embodiment. [Figure 9] FIG. 9 is an enlarged view of the main part of FIG. 8. [Figure 10] FIG. 2 is a perspective view of an electric vertical take-off and landing aircraft on which the bearing device is mounted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present disclosure is not necessarily limited to the numbers, amounts, etc., unless otherwise specified. The same reference numbers are given to the same parts and corresponding parts, and duplicate descriptions may not be repeated. It is intended from the beginning that the configurations in the embodiments will be used in appropriate combination.

[0016] [Embodiment 1] Fig. 1 is a cross-sectional view of a plane including a rotating shaft of a bearing device of a first embodiment. As the bearing device 1 shown in Fig. 1, a bearing with a wireless sensor is exemplified. The bearing device 1 includes a bearing B, an outer ring 7, a magnetic ring 8, a stator 9, and a circuit board 10. The bearing B includes an outer ring 2, an inner ring 3, rolling elements 4, a retainer 5, and a seal 6. The outer ring 7 is fixed to the inner diameter surface of the outer ring 2. A heat insulating part 11 is fixed to the inner diameter surface of the outer ring 7.

[0017] The heat insulating part 11 is provided with a partition wall 11a. The heat insulating part 11 has two spaces formed on the bearing B side and the opposite bearing side. The end face 11b on the bearing B side abuts against the end face of the outer ring 7. The magnetic ring 8 is fixed to the outer diameter surface of the inner ring 3. The stator 9 is fixed to the space on the opposite bearing side of the partition wall 11a of the heat insulating part 11 so as to face the magnetic ring 8. The stator 9 is fixed to the outer ring 7 via the heat insulating part 11. Note that the bearing device 1 may have a space on the bearing B side without providing the end face 11b. Specifically, in the bearing device 1, the heat insulating part 11 having an L-shaped cross section that also serves as the partition wall 11a is fixed to the outer ring 7, and the depth is adjusted to provide a space on the bearing B side.

[0018] The circuit board 10 is fixed to the end face of the outer ring 7 adjacent to the end face of the outer ring 2 of the bearing B by a screw, an adhesive, or the like. The circuit board 10 is arranged in the bearing B side space of the partition wall 11a of the heat insulating part 11. A lid 12 is arranged on the outer end face of the stator 9. The lid 12 is press-fitted or adhesively fixed to the inner diameter surface of the outer ring 7. The lid 12 is configured in a two-layer structure having a heat dissipation part 12a and a heat insulating layer 12b. The heat dissipation part 12a is arranged on the inner diameter side that abuts against the stator 9, and is formed of a metal material with high thermal conductivity (for example, aluminum, copper, iron material, etc.). The heat insulating layer 12b is arranged on the outer diameter side, and is formed of a heat insulating material with low thermal conductivity (for example, an insulating material such as resin). The lid 12 may be made entirely of an insulating material (non-conductive material) such as resin.

[0019] The magnetic ring 8 and the stator 9 constitute a generator G. The generator G is a claw pole generator. The bearing B is, for example, a deep groove ball bearing with balls as the rolling elements 4, and an inner ring rotating type with the inner ring 3 as the rotating ring and the outer ring 2 as the fixed ring will be described as an example here.

[0020] The magnetic ring 8 includes a core metal 8a and a multi-pole magnet 8b, and is fixed to the inner ring (rotating ring) 3. The multi-pole magnet 8b is formed by vulcanizing and bonding a magnetic material, for example a mixture of magnetic powder and rubber, to the core metal 8a, and then magnetizing the N poles and S poles alternately in the circumferential direction.

[0021] The stator 9 includes two identically shaped magnetic ring members 13 (13-1, 13-2), a bobbin 14, and a coil 15. The coil 15 has a winding wound around the bobbin 14 multiple times in the circumferential direction. Although an example using the bobbin 14 is shown here, the stator 9 may also be configured using an air-core coil that does not use the bobbin 14.

[0022] Mounted on the circuit board 10 are a power supply circuit 16 that rectifies the AC power generated by the generator G and converts it to DC, a sensor 17 that monitors the state of the bearing B, and a wireless communication circuit 20 that wirelessly transmits the output of the sensor 17 to the outside. The sensor 17 includes a temperature sensor 18 and an acceleration sensor 19. The temperature sensor 18 is mounted on the back surface of the circuit board 10 so that it can be disposed in a position close to the bearing B. The temperature sensor 18 is inserted into a recess 7a (groove or hole) provided on the end face of the outer ring 7.

[0023] The start and end (not shown) of coil 15 are connected to circuit board 10 via groove 12c provided on the side surface of lid 12 and groove 11c provided on the outer periphery of heat insulating part 11. AC power output from generator G as inner ring 3 rotates is converted to DC by power supply circuit 16. A protective film such as resin may be applied to the surface of circuit board 10.

[0024] The circuit board 10 on which the wireless communication circuit 20 is mounted is disposed opposite the heat insulating section 11. By using an insulator (non-conductive material) such as a resin having low thermal conductivity as the heat insulating section 11 and using an insulating material for the heat insulating layer 12b formed on the outer peripheral surface of the lid 12, a cylindrical insulator is formed between the outer ring 7 and the stator 9. As a result, the wireless communication circuit 20 has a structure that is not sealed with a conductive material such as a metal, so that wireless communication is possible using the antenna section 20a. The wireless communication circuit 20 may be formed as a separate substrate (not shown) and disposed between the lid 12 and the stator 9. In this case, the material of the portion of the lid 12 that faces the antenna section 20a of the wireless communication circuit 20 is preferably an insulating member.

[0025] The stator 9 of the generator G is thermally insulated from metal components such as the outer ring 7 by a heat insulating section 11. Heat generated by iron loss in the stator 9 when the magnetic ring 8 fixed to the inner ring 3 rotates to generate power is not directly conducted to the bearing B side. For this reason, only the heat generated by the rotation of the bearing B can be detected by the temperature sensor 18.

[0026] No seal 6 is provided on the side of bearing B where magnetic ring 8 is fixed. However, a lid 12 is provided to cover magnetic ring 8 and stator 9, and the gap between the components is narrow, forming a labyrinth seal (non-contact seal) structure that can prevent the intrusion of foreign matter, etc.

[0027] The lid 12 has a two-layer structure with a heat dissipation part 12a having a high thermal conductivity and a heat insulating layer 12b having a low thermal conductivity on its outer periphery. The lid 12 has a folded part 12d that wraps around the inner diameter side of the core metal 8a of the magnetic ring 8 to increase the volume and surface area of ​​the heat dissipation part 12a for cooling the stator 9. The folded part 12d improves the sealing performance of the lid 12.

[0028] Since the end face of the stator 9 abuts against the heat dissipation portion 12a, the heat generated by the stator 9 can be efficiently dissipated to the outside by the heat dissipation portion 12a. The heat insulating layer 12b prevents the temperature of the heat dissipation portion 12a from being directly transferred to the outer ring 7, thereby preventing the heat generated by the stator 9 from affecting the bearing B. The heat dissipation performance can be further improved by forming grooves (not shown) on the outer surface of the heat dissipation portion 12a to increase the surface area.

[0029] FIG. 2 is a diagram showing a schematic configuration of the generator G. The generator G is a claw-pole type generator. The magnetic rotor is composed of a ring-shaped multi-pole magnet 8b. The stator 9 is composed of a coil 15 and a magnetic yoke surrounding it. The magnetic yoke is composed of a magnetic ring member 13 (13-1, 13-2). The magnetic flux coming out of the N pole of the multi-pole magnet 8b enters the magnetic yoke from the claw 13b, which is a magnetic pole, and goes around the coil and enters the S pole of the multi-pole magnet 8b from the adjacent claw 13b. When the positions of the N pole and S pole of the multi-pole magnet 8b are interchanged due to the rotation angle of the magnetic rotor, the direction of the magnetic flux is reversed. The alternating magnetic field generated in this way generates an AC voltage at both ends of the coil 15.

[0030] The structure of the stator 9 will be described with reference to Figures 3 and 4. Figure 3 is a diagram showing a state in which two magnetic ring members 13 of the same shape are arranged opposite each other. In reality, a bobbin 14 with a coil 15 wound around it is stored in the space between the two magnetic ring members 13-1 and 13-2, but for ease of explanation, the bobbin 14 with the coil 15 wound around it is omitted here. Figure 4 is a diagram showing a state in which the two magnetic ring members 13 are fitted together.

[0031] Grooves 13a and claws 13b opening toward the shaft are formed alternately in a comb-like shape on the inner peripheral end of the magnetic ring member 13 (13-1, 13-2). A recess 13c and a protrusion 13d are formed on the end face 13f of the magnetic ring member 13 (13-1, 13-2). The magnetic ring member 13 is designed so that when two magnetic ring members 13-1 and 13-2 of the same shape are opposed to each other and the claws 13b are arranged alternately, the protrusion 13d of the magnetic ring member 13-2 is arranged in relation to the recess 13c of the magnetic ring member 13-1, so that the recess 13c and the protrusion 13d engage with each other.

[0032] The recesses 13c and protrusions 13d on the end faces 13f of each magnetic ring member 13 are fitted together so that the claws 13b of each magnetic ring member 13 are arranged alternately. In this manner, it becomes easy to arrange the claws 13b of each magnetic ring member 13 so that the gaps between the claws 13b are uniform. In addition, since a plurality of recesses 13c and protrusions 13d are arranged in the circumferential direction, the magnetic ring members 13 can be fixed in position without being displaced in the circumferential direction.

[0033] The number of magnetized poles and the magnetic pole pitch of the N poles and S poles of the magnetic ring 8 are equal. A hole 13e provided in the side surface of the magnetic ring member 13 is used to pull out the end of the coil 15 to the outside.

[0034] 1 has a circuit board 10 fixed to a position close to the bearing B. Therefore, the bearing device 1 can use an acceleration sensor 19 mounted on the circuit board 10 to measure the acceleration caused by vibrations generated by the bearing B before the vibrations attenuate. Furthermore, in abnormality diagnosis based on the measured acceleration, a signal with little attenuation can be used for diagnosis, making it possible to accurately diagnose an abnormality in the bearing B.

[0035] In the bearing device 1, the stator 9 and the outer ring 7 are thermally insulated by the heat insulating portion 11. Therefore, the bearing device 1 is not affected by the heat generated by the stator 9, and the temperature rise of the bearing B can be accurately monitored by the temperature sensor 18 mounted on the circuit board 10. The bearing device 1 is provided with a lid 12 having a heat dissipation portion 12a with excellent thermal conductivity and good heat dissipation properties at a portion that abuts against the outer end face of the stator 9, so that the heat generated by the stator 9 can be effectively dissipated to the outside. The lid 12 of the bearing device 1 is provided with a heat insulating layer 12b made of an insulator with low thermal conductivity and excellent heat insulation properties on the outer periphery of the heat dissipation portion 12a, so that the temperature of the heat dissipation portion 12a is not directly transmitted to the outer ring 7, and the heat generated by the stator 9 does not affect the bearing B.

[0036] When communicating the sensor output wirelessly, it is preferable that at least the antenna portion 20a of the circuit board 10 on which the wireless communication circuit 20 is mounted faces the heat insulating portion 11 at a position that does not overlap with the stator 9 in the axial direction. By using an insulator (non-conductive material) such as resin for the heat insulating portion 11 and the heat insulating layer 12b, a ring-shaped insulator layer is formed between the outer ring 7 and the stator 9. By using an insulator layer that transmits radio waves, the wireless communication circuit 20 has a structure that is not sealed with a conductive material such as metal, enabling wireless communication.

[0037] For example, when Bluetooth Low Energy (registered trademark) (frequency 2.4 GHz, wavelength λ approximately 125 mm) is used as the communication standard for the wireless communication circuit 20, radio waves can be emitted to the outside of the bearing device 1 if there is a gap in the insulator of λ / 2 or more.

[0038] In the bearing device 1, a claw pole generator has been described as an example of the generator G, but other generators may also be used.

[0039] In the bearing device 1, the surface of the magnetic ring 8 facing the stator 9 may be subjected to a heat insulating coating to suppress a temperature rise due to radiant heat from the stator 9, and to suppress the transfer of heat to the inner ring 3.

[0040] The bearing device 1 may have the outer ring 2 of the bearing B fixed to a rotating member and the inner ring 3 fixed to a stationary member. Instead of fixing the outer ring 7 to the inner diameter surface of the outer ring 2 of the bearing B, the bearing device 1 may have a configuration in which the end of the outer ring 2 is extended in the axial direction and the outer ring 7 is omitted.

[0041] [First Modification of First Embodiment] 5 to 7 are diagrams illustrating a bearing device 1A according to a first modified example of the first embodiment. FIG. 5 is a cross-sectional view of the bearing device 1A according to the first modified example of the first embodiment. FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. 5. For ease of understanding, the bobbin 14 is indicated by a two-dot chain line, and the coil 15 is omitted. FIG. 7 is a perspective view illustrating the shape of a stator 9A.

[0042] In the bearing device 1A shown in Fig. 5, the circuit board 10 on which the sensor 17 is mounted is fixed to the end face of the outer ring 7 so that the circuit board 10 can be disposed close to the bearing B. Fixing methods that can be used include screwing, adhesives, etc. In the first modified example, fixing with an adhesive is used, so that fixing can be performed in a small space.

[0043] As shown in Fig. 5, the heat insulating section 11A has an L-shaped cross section. As shown in Fig. 6, the heat insulating section 11A also has a C-shape with a cutout portion 11Ad formed in part of its circumference to avoid interference with the circuit board 10. The cutout portion 11Ad is in the range indicated by C in Fig. 6. The partition wall 11Aa is part of the heat insulating section 11A and is disposed so as to abut against the end face of the outer ring 7. As shown in Fig. 6, the circuit board 10 is disposed within the region of the cutout portion 11Ad of the heat insulating section 11A when viewed from the axial direction.

[0044] 7, the stator 9A has a portion of the magnetic ring member 13A (13A-1, 13A-2) removed so as not to interfere with the circuit board 10. The structure has a removed portion 9A1, and the bobbin 14 is exposed. The removed portion 9A1 is in the range of R in FIG. 6.

[0045] As shown in FIG. 6, the range C of the cutout portion 11Ad of the heat insulating portion 11A is smaller than the range R of the removed portion 9A1 of the stator 9A. In this case, the magnetic ring member 13A and the circuit board 10 do not directly face each other, so that the radiant heat transferred from the magnetic ring member 13A to the circuit board 10 can be suppressed. In the removed portion 9A1, the bobbin 14 and the circuit board 10 face each other. The bobbin 14 is made of an insulator with a relatively low thermal conductivity, such as resin. This can suppress the heat generated in the coil 15 from being directly radiated to the circuit board 10.

[0046] A lid 12 is disposed on the outer end surface of the stator 9A. The lid 12 is fixed to the inner diameter surface of the outer ring 7. The lid 12 is formed in a two-layer structure having a heat dissipation portion 12a and a heat insulating layer 12b. The heat dissipation portion 12a is disposed in a portion that abuts against the outer end surface of the stator 9A, and has excellent thermal conductivity and good heat dissipation. The heat insulating layer 12b is disposed on the outer periphery of the heat dissipation portion 12a, and has low thermal conductivity and excellent heat insulation. Since the end surface of the stator 9A abuts against the heat dissipation portion 12a, the heat generated in the stator 9A can be efficiently dissipated to the outside by the heat dissipation portion 12a. Since the heat insulating layer 12b is configured so that the temperature of the heat dissipation portion 12a is not directly transmitted to the outer ring 7, it is possible to prevent the heat generated in the stator 9A from affecting the bearing B.

[0047] With a structure like that of bearing device 1A, no conductive member is arranged near the outside facing wireless communication circuit 20 mounted on circuit board 10, making it possible to radiate radio waves to the outside and perform wireless communication. In bearing device 1A of variation 1 of embodiment 1, stator 9A can be arranged closer to bearing B, making it possible to shorten the axial width of outer ring 7, and thus achieving the same effects as embodiment 1, as well as a reduction in the size of bearing device 1A.

[0048] [Modification 2 of the First Embodiment] The above-mentioned bearing devices 1 and 1A are configured to use a single row of bearings. The bearing devices 1 and 1A can also be applied to bearing devices using multiple rows of bearings used in spindle devices and the like. Figs. 8 and 9 are diagrams for explaining a modified example 2 of the first embodiment in which the configuration of the present disclosure is applied to a bearing device 90 of a spindle device 50. Fig. 8 is a cross-sectional view showing a schematic configuration of the modified example 2 of the first embodiment. Fig. 9 is an enlarged view of the main part S of Fig. 8, mainly showing the bearing device 90.

[0049] 8 is used, for example, as a built-in motor type spindle device for a machine tool. In this case, a motor 52 is built into one end of a spindle 51 supported by the spindle device 50 for the machine tool spindle, and a cutting tool such as an end mill (not shown) is connected to the other end.

[0050] 8 and 9, the spindle device 50 includes bearings 53 (53a, 53b), a spacer 54 disposed adjacent to the bearings 53a, 53b, a motor 52, and a bearing 55. The main shaft 51 is rotatably supported by a plurality of bearings 53a, 53b provided in a housing 57 embedded in the inner diameter portion of an outer cylinder 56. The bearing 53a includes an inner ring 53ia, an outer ring 53ga, a rolling element Ta, and a retainer Rta. The bearing 53b includes an inner ring 53ib, an outer ring 53gb, a rolling element Tb, and a retainer Rtb. The spacer 54 includes an inner ring spacer 54i and an outer ring spacer 54g. Wireless communication will be described later. To enable wireless communication, it is preferable that the rolling elements Ta and Tb are made of ceramic, which is an insulating material, and the retainers Rta and Rtb are made of resin.

[0051] An inner ring 53ia of bearing 53a and an inner ring 53ib of bearing 53b, which are spaced apart in the axial direction, are fitted in an interference fit state (press-fit state) on main shaft 51. An inner ring spacer 54i is disposed between inner ring 53ia and inner ring 53ib, and an outer ring spacer 54g is disposed between outer ring 53ga and inner ring 53gb.

[0052] The bearings 53a and 53b are capable of applying a preload with an axial force as described later, and may be angular ball bearings, deep groove ball bearings, tapered roller bearings, etc. An angular ball bearing is used in the bearing device 90 shown in Figures 8 and 9, and the two bearings 53a and 53b are installed in a back-to-back configuration (DB combination).

[0053] The outer ring spacer 54g is divided into two in the axial direction, a first outer ring spacer 54g1 and a second outer ring spacer 54g2. A stator 9 of the generator G is fixed between the first outer ring spacer 54g1 and the second outer ring spacer 54g2. A magnetic ring 8 is fixed to the outer peripheral surface of the inner ring spacer 54i. As in FIG. 2, the generator G is configured such that the claws 13b of the stator 9 and the multi-pole magnets 8b of the magnetic ring 8 face each other with a gap therebetween. The generator G is a claw-pole generator. Here, a structure in which the outer ring spacer 54g is divided into two has been described, but a structure in which it is not divided may also be used.

[0054] The magnetic ring 8 includes a core 8a and a multi-pole magnet 8b. The multi-pole magnet 8b is formed by vulcanizing and bonding a magnetic material, for example a mixture of magnetic powder and rubber, to the core 8a, and then magnetizing the N pole and S pole alternately, and is fixed to the inner ring spacer 54i. The stator 9 includes two identically shaped magnetic ring members 13 (13-1, 13-2), a bobbin 14, and a coil 15. The coil 15 is wound around the bobbin 14 multiple times in the circumferential direction. In the second modified example, an example in which the bobbin 14 is used is shown, but an air-core coil without the bobbin 14 may also be used.

[0055] Between the stator 9 and the outer ring spacer 54g, a heat insulating portion 71 (71a, 71b) is provided. The bearing device 90 is structured so that heat generated in the stator 9 due to iron loss or the like is not directly conducted to the outer ring spacer 54g. In the bearing device 90, a cylindrical heat dissipation portion 72 with good thermal conductivity is inserted so as to contact one side surface of the stator 9. The heat dissipation portion 72 can efficiently dissipate heat generated in the stator 9 to the outside. The stator 9 and the heat dissipation portion 72 are disposed on the inner diameter surface of a first heat insulating portion 71a having an L-shaped cross section. A second heat insulating portion 71b is disposed between the heat dissipation portion 72 and the side surface of the second outer ring spacer 54g2.

[0056] The outer ring spacer 54g and the stator 9 are thermally insulated by the heat insulating portions 71 (71a, 71b). The inner diameter surface of the heat dissipation portion 72 is formed with an uneven portion 72a. The uneven portion 72a increases the surface area of ​​the heat dissipation portion 72, thereby improving the heat dissipation performance. A further heat dissipation portion may be arranged on the opposite side of the heat dissipation portion 72 from the stator 9. The heat dissipation portion 72 may be provided with a flow path (not shown) through which a cooling medium can pass. By flowing bearing cooling air through the flow path of the heat dissipation portion 72, the heat dissipation performance of the bearing device 90 can be further improved.

[0057] A groove 54g1a is formed on the end face of the first outer ring spacer 54g1. The circuit board 10 is mounted inside the groove 54g1a. The circuit board 10 is mounted with a power supply circuit 16 that rectifies AC power generated by the generator G to convert it to DC, a sensor 17 that monitors the state of the bearing device 90, and a wireless communication circuit 20 that wirelessly transmits the output of the sensor 17 to the outside. The ends 15a and 15b of the coil 15 are connected to the circuit board 10 through a hole 71a1 in the first heat insulating part 71a and a hole 54g1b in the first outer ring spacer 54g1. It is preferable that the holes 71a1 and 54g1b are sealed with a sealant after wiring to prevent oil and the like from entering the circuit board 10 side.

[0058] AC power output from the electric machine G as the main shaft 51 rotates is converted to DC by the power supply circuit 16. A lid 73 serving as a protective member for protecting the circuit board 10 is made of a nonmetallic (nonconductive) insulator such as resin, and is fixed to the groove 54g1a. Note that, in the bearing device 90, instead of the lid 73, the inside of the groove 54g1a including the circuit board 10 may be sealed with a resin molding material.

[0059] As the sensors 17, a temperature sensor 18, an acceleration sensor 19, a load sensor 21, etc. are mounted as necessary. The outputs of the sensors are wirelessly transmitted to the outside using a wireless communication circuit 20.

[0060] The single-row rolling bearing 55 is a cylindrical roller bearing. The angular contact ball bearings 53a and 53b support radial and axial loads acting on the spindle device 50. The single-row cylindrical roller bearing 55 supports the radial load acting on the spindle device 50 for the machine tool main shaft.

[0061] A cooling medium flow path GV is formed in the housing 57. The bearings 53a, 53b can be cooled by flowing a cooling medium through the cooling medium flow path GV. If grease-lubricated bearings are used as the bearings 53a, 53b, no lubricant supply path is required. However, if lubrication with air oil or the like is required, a lubricant supply path is provided in the outer ring spacer 54g. Note that the lubricant supply path is not shown here.

[0062] During assembly, first, front cover 60, bearing 53a, spacer 54, bearing 53b, and spacer 58 are inserted onto main shaft 51 in this order, and an initial preload is applied by tightening nut 59. Then, main shaft 51 to which bearings 53a and 53b are attached is inserted into housing 57 until the right side of outer ring 53gb of bearing 53b in FIG. 9 abuts against stepped portion 57a ​​provided on housing 57. Finally, main shaft 51 is fixed to housing 57 by pressing outer ring 53ga of left bearing 53a with front cover 60.

[0063] By tightening the nut 59, a force acts on the end face of the inner ring 53ib of the bearing 53b via the spacer 58, pressing the inner ring 53ib toward the inner ring spacer 54i. This force is transmitted through the inner ring 53ib, the rolling elements Tb, and the outer ring 53gb, applying a preload between the raceway surfaces of the inner ring 53ib and the outer ring 53gb and the rolling elements Tb, and is also transmitted from the outer ring 53gb to the outer ring spacer 54g.

[0064] This force is transmitted to the outer ring 53ga, rolling element Ta, and inner ring 53ia in the bearing 53a, and a preload is also applied between the raceway surfaces of the inner ring 53ia and outer ring 53ga of the left bearing 5a and the rolling element Ta. The preload applied to the bearings 53a and 53b is determined by the amount of movement limited by the dimensional difference between the width of the outer ring spacer 54g and the width of the inner ring spacer 54i, for example.

[0065] In the single-row bearing 55 shown in Fig. 8, the inner ring 55a is positioned in the axial direction by a cylindrical member 61 fitted onto the outer periphery of the main shaft 51 and an inner ring holder 62. The inner ring holder 62 is prevented from coming off by a nut 63 screwed onto the main shaft 51. The outer ring 55b of the bearing 55 is sandwiched between a positioning member 65 and a positioning member 66 fixed to an end member 64. The inner ring 55a slides integrally with the end member 64 in response to the expansion and contraction of the main shaft 51.

[0066] Motor 52 for driving main shaft 51 is disposed at an axially intermediate position between bearing 53b and single-row bearing 55 in space 67 formed between main shaft 51 and outer cylinder 56. A rotor 68 of motor 52 is fixed to a cylindrical member 61 fitted onto the outer periphery of main shaft 51, and a stator 69 of motor 52 is fixed to the inner periphery of outer cylinder 56. Note that a coolant flow path for cooling motor 52 is not shown here.

[0067] As explained above, the circuit board 10 on which the generator G, power supply circuit 16, sensor 17, wireless communication circuit 20, etc. are mounted is disposed on the outer ring spacer 54g. The bearing device 90 can wirelessly transmit the output of the sensor 17 to the outside using the generated power, making it possible to monitor the operating status of the spindle device 50. The bearing device 90 may determine the presence or absence of an abnormality from the output of each sensor within the circuit board 10 and transmit the determination result wirelessly.

[0068] In order to allow radio waves emitted from the wireless communication circuit 20 to pass through the gap between the outer ring 53ga and the inner ring 53ia of the bearing 53a, it is preferable that at least the material of the rolling element Ta of the bearing 53 is ceramic, which is an insulator, and that the material of the cage Rta is resin, which is an insulator. The radio waves are then released to the outside through the gap 70 of the labyrinth seal formed between the main shaft 51 and the front cover 60. Note that simplifying the structure of the labyrinth seal and enlarging the gap 70 is preferable in terms of the radio wave environment. If the radio waves are directional, it is preferable to provide a wireless transceiver or repeater (not shown) below the main shaft.

[0069] The stator 9 of the generator G mounted on the spindle device 50 is thermally insulated from the outer ring spacer 54g by the heat insulating portion 71. Therefore, in the bearing device 90, heat generated by iron loss in the stator 9 during operation of the spindle device 50 is prevented from being conducted to the outer ring spacer 54g, and the temperature rise caused by the rotation of the bearing 53 can be accurately measured. This makes it possible to more accurately detect abnormalities in the bearing 53. Since the bearing device 90 does not have wiring drawn out from the outer ring spacer 54g, there is no need to machine grooves for drawing out wiring on the inner diameter side of the housing 57, improving ease of assembly.

[0070] [Configuration of electric vertical take-off and landing aircraft] In recent years, flying cars, or cars that can fly, have been attracting attention as an alternative means of transportation to automobiles. Flying cars are expected to be used in a variety of situations, including local and inter-regional travel, tourism and leisure, emergency medical care, and disaster relief.

[0071] Vertical take-off and landing aircraft (VTOL) are attracting attention as flying cars. VTOLs can ascend and descend vertically between the sky and the take-off and landing site, so they do not require runways and are highly convenient. In particular, in recent years, due to societal demands for reducing CO2 emissions, electric vertical take-off and landing aircraft (eVTOL), which fly using batteries and motors, have become the mainstream in development.

[0072] The bearing device of the above embodiment may be mounted on such an electric vertical take-off and landing aircraft. The configuration of an electric vertical take-off and landing aircraft on which the bearing device 1 of the first embodiment is mounted will be described as an example with reference to FIG.

[0073] 10, electric vertical take-off and landing aircraft 101 is a multicopter having a main body 102 located in the center of the aircraft body, and four drive units 103 arranged on the front, rear, left and right sides. Drive units 103 are devices that generate lift and thrust for electric vertical take-off and landing aircraft 101. Electric vertical take-off and landing aircraft 101 flies by being driven by drive units 103. Electric vertical take-off and landing aircraft 101 may have multiple drive units 103, and is not limited to four.

[0074] The main body 102 has a living space capable of accommodating a crew member (for example, about one or two people). This living space is provided with an operating system for determining the direction of travel and altitude, and instruments for indicating altitude, speed, flight position, and the like. Four arms 102a extend from the main body 102, and a drive unit 103 is provided at the tip of each arm 102a. A ring portion that covers the rotating periphery of the rotor 104 is integrally provided on the arm 102a to protect the rotor 104. In addition, a skid 102b that supports the aircraft when it lands is provided below the main body 102.

[0075] The drive unit 103 has a pair of upper and lower rotors 104 and a motor device 105 that rotates the rotors 104. In the drive unit 103, the pair of upper and lower rotors 104 are provided on both axial sides of the motor device 105. Each of the pair of upper and lower rotors 104 has two blades extending radially outward.

[0076] The main body 102 is provided with a battery (not shown) and a control device (not shown). The control device is also called a flight controller. The electric vertical take-off and landing aircraft 101 is controlled by the control device, for example, as follows. The control device outputs a command to change the rotation speed to the motor device 105, which should adjust the lift based on the difference between the current attitude and the target attitude. Based on the command, an amplifier provided in the motor device 105 adjusts the amount of power sent from the battery to the motor device 105, and the rotation speed of the motor device 105 (and the rotor 104) is changed. Furthermore, the adjustment of the rotation speed of the motor device 105 is performed simultaneously for multiple motor devices 105, and the attitude of the aircraft is determined thereby.

[0077] When the bearing device 90 of the second modification of the first embodiment is used for the motor device 105, the main shaft 51 is used as a rotating shaft, the above-mentioned upper rotor is attached to one end of the rotating shaft, and the rotor 68 of the motor device 105 is attached to the other end. The rotor 68 is disposed opposite to a stator 69 fixed to the cylindrical member 61, and is rotatable relative to the stator 69. The motor device 105 can adopt the configuration of an outer rotor type brushless motor or an inner rotor type brushless motor.

[0078] The motor device 105 has an outer cylinder 56, a housing 57, a rotor 68, a stator 69, an amplifier (not shown), and two bearings 53a and 53b. A cooling medium flow path is provided between the outer cylinder 56 and the housing 57. By flowing a cooling medium through this flow path, an excessive temperature rise is prevented. The material of the outer cylinder 56 and the housing 57 is not particularly limited, and may be, for example, an iron-based material, CFRP (carbon fiber reinforced plastic), or the like.

[0079] Furthermore, when the motor device 105 is used in the bearing device 90, the bearing device 90 rotatably supports a rotating shaft within the outer cylinder 56. The bearing device 90 is structured so that heat generated by the stator 9 due to iron loss or the like is not directly conducted to the outer ring spacer 54g. A groove 54g1a is formed in an end face of the first outer ring spacer 54g1. A circuit board 10 is mounted inside the groove 54g1a. On the circuit board 10, a power supply circuit 16 that rectifies AC power generated by the generator G and converts it to DC, a sensor 17 that monitors the state of the bearing device 90, and a wireless communication circuit 20 that wirelessly transmits the output of the sensor 17 to the outside are mounted.

[0080] The bearing configuration in the drive unit may be other. In Fig. 10, the rotating shaft of the motor device 105 and the rotating shaft of the rotor 104 are the same rotating shaft, but the rotating shaft of the motor device 105 and the rotating shaft of the rotor 104 may be connected via a transmission mechanism. In this case, the bearing device supporting the rotating shaft in the drive unit may be the bearing device supporting the rotating shaft of the motor device 105, or may be the bearing device supporting the rotating shaft of the rotor.

[0081] (summary) The present disclosure relates to a bearing device 1 including a bearing. The bearing device 1 includes an outer ring 2, an inner ring 3, a plurality of rolling elements 4 arranged between the outer ring 2 and the inner ring 3, an outer ring 7 fixed to one of the outer ring 2 and the inner ring 3, a magnetic ring 8 fixed to the other of the outer ring 2 and the inner ring 3 so as to face the outer ring 7, a cylindrical heat insulating part 11 fixed to the outer ring 7 and made of a nonmetallic insulator with low thermal conductivity and having a partition wall 11a extending in the radial direction, and a stator 9 fixed on the opposite side of the bearing B across the partition wall 11a. The magnetic ring 8 is arranged to face the stator 9, and the stator 9 and the magnetic ring 8 constitute a generator G. The bearing device 1 further includes a circuit board 10 fixed in a space on the bearing B side relative to the partition wall 11a. The circuit board 10 includes a power supply circuit 16 that rectifies the power generated by the generator G to create a DC power supply, at least one sensor 17 that detects the condition of the bearing B, and a wireless communication circuit 20 that wirelessly transmits the output of the at least one sensor 17 to the outside.

[0082] With this configuration, the stator 9 and bearing B of the generator G are thermally insulated by the insulating section 11, so that the thermal conduction of heat generated by iron loss in the stator 9 to the bearing B and outer ring 7 can be reduced. As a result, by arranging a temperature sensor 18 as the sensor 17 near the bearing B, it is possible to accurately detect only the temperature rise caused by the rotation of the bearing B. By arranging an acceleration sensor 19 as the sensor 17 near the bearing B, it is possible to measure the acceleration due to vibrations caused by the bearing B before the vibrations attenuate. The bearing device 1 has a simple structure and can be made compact.

[0083] Preferably, the rotor further includes a heat dissipation portion 12a arranged so as to be in contact with the stator 9 and made of a material with high thermal conductivity, and a heat insulating layer 12b arranged on the outer peripheral surface of the heat dissipation portion 12a and made of a heat insulating material with low thermal conductivity. The heat insulating layer 12b abuts against the outer ring 7.

[0084] By having such a configuration, the bearing device 1 can efficiently dissipate heat generated by the stator 9 to the outside through the heat dissipation section 12a, and the insulating layer 12b prevents the temperature of the heat dissipation section 12a from being directly transmitted to the outer ring 7, thereby preventing the heat generated by the stator 9 from affecting the bearing B.

[0085] Preferably, either the outer ring 2 or the inner ring 3 functions as a stationary ring of the bearing device 1. The circuit board 10 is fixed to the outer ring 7 in a space formed between an end face of the outer ring 7 abutting on the end face of the stationary ring and a partition wall 11a of the heat insulating part 11.

[0086] With this configuration, the circuit board 10 is disposed near the bearing B and is thermally insulated by the partition wall 11a of the insulating section 11, so that the temperature rise or acceleration accompanying the rotation of the bearing B can be accurately measured.

[0087] Preferably, the wireless communication circuit 20 includes an antenna portion 20a therein. The antenna portion 20a is disposed at a position not overlapping with the stator 9 in the axial direction and facing the heat insulating portion 11.

[0088] With this configuration, the antenna portion 20a can transmit radio waves to the outside of the bearing device 1 without being affected by conductive materials such as metals.

[0089] Preferably, in the bearing device 1A, a cutout portion 11Ad formed in a part of the outer periphery of the insulating portion 11A overlaps with a removed portion 9A1 in which a circumferential portion of the magnetic ring member 13 constituting the stator 9A is removed to expose the bobbin 14, and the circuit board 10 is positioned within the area of ​​the cutout portion 11Ad.

[0090] By providing such a configuration, the bearing device 1A can have the stator 9A disposed closer to the bearing B, so that the axial width of the outer ring 7 can be shortened, enabling miniaturization.

[0091] Preferably, in the bearing device 90, the outer ring spacer 54g serves as the fixed member. By being provided with such a configuration, the bearing device 90 can accurately measure the temperature rise or acceleration accompanying the rotation of the bearing 53 in a configuration including the bearings 53a and 53b.

[0092] Preferably, either the outer ring 2 or the inner ring 3 functions as a stationary ring of the bearing device 90. The circuit board 10 is fixed inside a groove 54g1a formed in one end of the outer ring spacer 54g adjacent to the stationary ring. A lid 73 as a protective member for protecting the circuit board 10 and a plurality of rolling elements Ta facing the lid 73 are made of an insulator. A gap 70 is provided between a front lid 60 that abuts against the other end of the stationary ring of the bearing 53 and a main shaft 51 supported by the front lid 60 and the bearing 53.

[0093] By being configured in this manner, the bearing device 90 can emit radio waves transmitted from the wireless communication circuit 20 to the outside through the gap 70 of the labyrinth seal formed between the main shaft 51 and the front cover 60 .

[0094] Preferably, the bearing device 90 may be applied to the spindle device 50 . By providing such a configuration, the temperature rise or acceleration accompanying the rotation of the bearing 53 in the spindle device 50 can be accurately measured.

[0095] Preferably, the bearing device 1 may be applied to an electric vertical take-off and landing aircraft 101 that has a rotor 104 rotatably supported by the bearing device 1 and flies by rotating the rotor 104.

[0096] With this configuration, it is possible to accurately measure the temperature rise or acceleration associated with the rotation of the bearings in electric vertical take-off and landing aircraft 101.

[0097] 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]

[0098] 1,1A,90 bearing device, 2,53ga,53gb,55b outer ring, 3,53ia,53ib,55a inner ring, 4,Ta,Tb rolling element, 5,Rta,Rtb retainer, 5a,5b,53,53a,53b,55,B bearing, 6 seal, 7 outer ring, 8 magnetic ring, 8a core, 8b multi-pole magnet, 9,9A stator, 9A1 removal portion, 10 circuit board, 11,11A,71 heat insulating portion, 11Aa,11a partition wall, 11Ad cutout portion, 12,73 cover, 12a,72 heat dissipation portion, 12b heat insulating layer, 13,13A magnetic ring member, 14 bobbin, 15 coil, 16 power circuit, 17 sensor, 18 temperature sensor, 19 Acceleration sensor, 20 wireless communication circuit, 20a antenna portion, 50 spindle device, 51 main shaft, 54g outer ring spacer, 54i inner ring spacer, 60 front cover, 71a first insulation portion, 71b second insulation portion, G generator.

Claims

1. A bearing device including a bearing, The outer ring and With the inner circle, A plurality of rolling elements disposed between the outer ring and the inner ring; a fixing member fixed to one of the outer ring and the inner ring; a magnetic ring fixed to the other of the outer ring and the inner ring so as to face the fixed member; a cylindrical heat insulating portion fixed to the fixing member, made of a nonmetallic insulator having low thermal conductivity, and having a partition wall extending in a radial direction; a stator fixed to the opposite side of the partition wall from the bearing, the magnetic ring is disposed to face the stator, the stator and the magnetic ring constitute a generator, the bearing device further includes a circuit board fixed in the space on the bearing side relative to the partition wall, The circuit board includes: a power supply circuit that rectifies the power generated by the generator to generate a DC power supply; at least one sensor for detecting a condition of the bearing; and a wireless communication circuit that wirelessly transmits an output of the at least one sensor to an outside.

2. a heat dissipation portion that is disposed so as to be in contact with the stator and is made of a material having high thermal conductivity; A heat insulating layer is disposed on the outer circumferential surface of the heat dissipation portion and is made of a heat insulating material having a low thermal conductivity. The bearing device according to claim 1 , wherein the heat insulating layer abuts against the fixed member.

3. One of the outer ring and the inner ring functions as a stationary ring of the bearing device, 3. The bearing device according to claim 1, wherein the circuit board is fixed to the fixed member in a space formed between an end face of the fixed member that abuts against an end face of the stationary ring and the partition wall of the heat insulating portion.

4. the wireless communication circuit includes an antenna unit therein; The bearing device according to claim 1 , wherein the antenna portion is disposed at a position not overlapping with the stator in the axial direction and facing the heat insulating portion.

5. a cutout portion formed in a part of the outer periphery of the heat insulating portion and a removed portion in which a circumferential portion of a magnetic ring member constituting the stator is removed to expose the bobbin are overlapped, The bearing device according to claim 1 , wherein the circuit board is disposed within the region of the cutout portion.

6. The bearing device according to claim 1 or 2, wherein the fixed member is an outer ring spacer.

7. One of the outer ring and the inner ring functions as a stationary ring of the bearing device, The circuit board is fixed inside a groove formed in one end of the outer ring spacer adjacent to the stationary ring, a protective member for protecting the circuit board and the rolling elements facing the protective member are made of insulating materials, 7. The bearing device according to claim 6, wherein a gap is provided between a lid that abuts against the other end of the stationary ring of the bearing and a main shaft supported by the lid and the bearing.

8. A spindle device comprising the bearing device according to any one of claims 1 to 7.

9. A bearing device according to any one of claims 1 to 7, a rotor supported rotatably by the bearing device, An electric vertical take-off and landing aircraft that flies by rotating the rotor.

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