JP7612484B2 - Bearing device, spindle device, and electric vertical take-off and landing aircraft - Google Patents

Description

The present disclosure relates to a bearing device, a spindle device, and an electric vertical take-off and landing aircraft.

It is known to combine a bearing with a generator and use it as a power source for sensors, wireless communication, etc. The 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.

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

The magnetic ring housing the coil is fitted onto 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 transmission means that wirelessly transmits the output of the rotation sensor is installed in the stepped portion extending from the flange portion of the outer diameter surface of the cover to the small diameter portion.

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

In the wireless sensor bearing 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 unit (coil) as power is generated, and a rise in temperature in the operating environment. In the wireless sensor bearing of Patent Document 2, heat dissipation fins are provided on the outside of the cover to prevent the radio circuit and power supply circuit attached to the cover from breaking down due to the effects of heat.

JP 2006-170624 A JP 2019-7580 A

The magnetic ring described in Patent Document 1 is fitted directly onto the inner diameter surface of the outer member (outer ring) of the wheel 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 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 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 bearing, it is difficult to place an acceleration sensor close to the wheel bearing because of the presence of the outer member.

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 circumference 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. As a result, heat generated during 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 there is an abnormality in the bearing.

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

The present disclosure has been made to solve the above problems, and its purpose is to provide a small bearing device, a spindle device, and an electric vertical take-off and landing aircraft that can accurately measure the temperature rise that accompanies the rotation of the bearing.

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 radially extending partition wall, 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 of the partition wall. The circuit board includes a power supply circuit that rectifies the power generated by the generator to create a DC 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.

This disclosure provides a small bearing device that can accurately measure the temperature rise that occurs with the rotation of the bearing.

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

The following describes in detail the embodiments of the present disclosure with reference to the drawings. In the embodiments described below, when numbers, quantities, etc. are mentioned, the scope of the present disclosure is not necessarily limited to those numbers, quantities, etc., unless otherwise specified. The same reference numbers are used for the same parts and equivalent 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 combinations.

[First embodiment]
Fig. 1 is a cross-sectional view of a plane including a rotating shaft of a bearing device of embodiment 1. 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 portion 11 is fixed to the inner diameter surface of the outer ring 7.

The insulating part 11 is provided with a partition wall 11a. Two spaces are formed in the insulating part 11, one on the bearing B side and the other on the opposite side. The end face 11b on the bearing B side abuts 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 side of the partition wall 11a of the insulating part 11 so as to face the magnetic ring 8. The stator 9 is fixed to the outer ring 7 via the 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 insulating part 11, which has an L-shaped cross section and also serves as the partition wall 11a, is fixed to the outer ring 7, and a space is provided on the bearing B side by adjusting the depth.

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 screws, adhesive, or the like. The circuit board 10 is arranged in the bearing B side space of the bulkhead 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 (e.g., aluminum, copper, iron, 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 (e.g., insulating material such as resin). The lid 12 may be made entirely of an insulating material (non-conductive material) such as resin.

The magnetic ring 8 and the stator 9 constitute the 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. Here, an inner ring rotating type is described as an example, in which the inner ring 3 is a rotating ring and the outer ring 2 is a fixed ring.

The magnetic ring 8 includes a core 8a and a multi-pole magnet 8b, and is fixed to the inner ring (rotating ring) 3. The multi-pole magnet 8b is made 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 and S poles alternately in the circumferential direction.

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. Here, an example using the bobbin 14 is shown, but the stator 9 may also be configured using an air-core coil that does not use the bobbin 14.

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 positioned 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.

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

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 with 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 is not sealed with a conductive material such as metal, so that wireless communication is possible using the antenna section 20a. The wireless communication circuit 20 may be formed as a separate board (not shown) and disposed between the lid 12 and the stator 9. In this case, it is preferable that the material of the part of the lid 12 that faces the antenna section 20a of the wireless communication circuit 20 is an insulating material.

The stator 9 of the generator G is thermally insulated from metal components such as the outer ring 7 by the insulating section 11. When the magnetic ring 8 fixed to the inner ring 3 rotates to generate electricity, heat generated by iron loss in the stator 9 is not directly transferred to the bearing B side. Therefore, only the heat generated by the rotation of the bearing B can be detected by the temperature sensor 18.

The seal 6 is not arranged on the side of the bearing B where the magnetic ring 8 is fixed. However, a lid 12 is provided to cover the magnetic ring 8 and the stator 9, and the gap between the parts is narrow, resulting in a labyrinth seal (non-contact seal) structure that prevents the intrusion of foreign matter, etc.

The lid 12 has a two-layer structure with a heat dissipation section 12a with high thermal conductivity and a heat insulating layer 12b with low thermal conductivity on its outer periphery. The lid 12 has a folded portion 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 section 12a for cooling the stator 9. The folded portion 12d improves the sealing performance of the lid 12.

The end face of the stator 9 abuts against the heat dissipation section 12a, so that the heat generated by the stator 9 can be efficiently dissipated to the outside by the heat dissipation section 12a. The insulating layer 12b prevents the temperature of the heat dissipation section 12a from being directly transferred to the outer ring 7, so that the heat generated by the stator 9 does not affect the bearing B. The heat dissipation performance can be further improved by forming grooves (not shown) on the outer surface of the heat dissipation section 12a to increase the surface area.

Figure 2 shows the schematic configuration of generator G. 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 magnetic ring members 13 (13-1, 13-2). The magnetic flux emitted from the N pole of the multi-pole magnet 8b enters the magnetic yoke through the claw 13b, which is a magnetic pole, and passes around the coil and enters the S pole of the multi-pole magnet 8b through the adjacent claw 13b. When the positions of the N pole and S pole of the multi-pole magnet 8b are swapped depending on 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.

The structure of the stator 9 will be explained using Figures 3 and 4. Figure 3 is a diagram showing two magnetic ring members 13 of the same shape 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 to make the explanation easier, the bobbin 14 with the coil 15 wound around it is omitted here. Figure 4 is a diagram showing the two magnetic ring members 13 fitted together.

Grooves 13a and claws 13b that open toward the shaft are formed alternately in a comb-like shape on the inner peripheral end of the magnetic ring members 13 (13-1, 13-2). Recesses 13c and protrusions 13d are formed on the end faces 13f of the magnetic ring members 13 (13-1, 13-2). The magnetic ring members 13 are designed so that when two identically shaped magnetic ring members 13-1 and 13-2 are opposed to each other and the claws 13b are arranged alternately, the protrusions 13d of the magnetic ring member 13-2 are arranged in relation to the recesses 13c of the magnetic ring member 13-1, so that the recesses 13c and the protrusions 13d engage with each other.

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 on each magnetic ring member 13 are arranged alternately. In this way, 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 multiple recesses 13c and protrusions 13d are arranged in the circumferential direction, the magnetic ring members 13 can be fixed in position without shifting in the circumferential direction.

The number of magnetized poles and the magnetic pole pitch of the N poles and S poles of the magnetic ring 8 are equal. In addition, the hole 13e on the side of the magnetic ring member 13 is used to pull out the end of the coil 15 to the outside.

The bearing device 1 shown in FIG. 1 has a circuit board 10 fixed in a position close to 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 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 abnormalities in bearing B.

In the bearing device 1, the stator 9 and the outer ring 7 are thermally insulated by the heat insulating part 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 part 12a with excellent thermal conductivity and good heat dissipation properties at the part that abuts 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 an insulating layer 12b made of an insulator with low thermal conductivity and excellent heat insulation properties on the outer periphery of the heat dissipation part 12a, so that the temperature of the heat dissipation part 12a is not directly transmitted to the outer ring 7, and the heat generated by the stator 9 does not affect the bearing B.

When communicating the sensor output wirelessly, it is preferable that in the circuit board 10 on which the wireless communication circuit 20 is mounted, at least the antenna portion 20a faces the 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 insulating portion 11 and the insulating layer 12b, a ring-shaped insulating layer is formed between the outer ring 7 and the stator 9. By using an insulating layer that transmits radio waves, the wireless communication circuit 20 has a structure that is not sealed with a conductive material such as metal, making wireless communication possible.

For example, if 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 outside the bearing device 1 if there is a gap in the insulator of λ/2 or more.

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.

In the bearing device 1, the surface of the magnetic ring 8 facing the stator 9 can be thermally coated to suppress the temperature rise caused by radiant heat from the stator 9 and to suppress the transfer of heat to the inner ring 3.

The bearing device 1 may be configured such that the outer ring 2 of the bearing B is fixed to a rotating member and the inner ring 3 is 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 be configured such that the end of the outer ring 2 is extended in the axial direction and the outer ring 7 is omitted.

[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 line VI-VI in Fig. 5. In order to make the drawings easier to understand, 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 the stator 9A.

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 placed close to the bearing B. Fixing methods that can be used include screwing and adhesives. In the first modified example, fixing with adhesives is used, so it can be fixed in a small space.

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 notch 11Ad formed on part of its circumference to avoid interference with the circuit board 10. The notch 11Ad is in the range C in FIG. 6. The partition wall 11Aa is part of the heat insulating section 11A and is positioned so as to abut against the end face of the outer ring 7. As shown in FIG. 6, the circuit board 10 is positioned within the area of the notch 11Ad of the heat insulating section 11A when viewed from the axial direction.

As shown in FIG. 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 R in FIG. 6.

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 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 faces the circuit board 10. The bobbin 14 is made of an insulator with a relatively low thermal conductivity, such as resin. This prevents the heat generated in the coil 15 from being directly radiated to the circuit board 10.

A lid 12 is placed 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 section 12a and a heat insulating layer 12b. The heat dissipation section 12a is placed in the 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 placed on the outer periphery of the heat dissipation section 12a and has low thermal conductivity and excellent heat insulation. Since the end surface of the stator 9A abuts against the heat dissipation section 12a, the heat generated in the stator 9A can be efficiently dissipated to the outside by the heat dissipation section 12a. The heat insulating layer 12b is configured so that the temperature of the heat dissipation section 12a is not directly transmitted to the outer ring 7, so that the heat generated in the stator 9A does not affect the bearing B.

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

[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. Figures 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. Figure 8 is a cross-sectional view showing a schematic configuration of the modified example 2 of the first embodiment. Figure 9 is a diagram showing an enlarged view of a main portion S of Figure 8, mainly showing the bearing device 90.

The spindle device 50 shown in FIG. 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.

8 and 9, the spindle device 50 includes bearings 53 (53a, 53b), a spacer 54 arranged 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 the 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 be made of ceramic, which is an insulator, and that the retainers Rta and Rtb be made of resin.

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

Bearings 53a and 53b are bearings that can be preloaded with an axial force, as described below, and can be angular ball bearings, deep groove ball bearings, tapered roller bearings, or the like. The bearing device 90 shown in Figures 8 and 9 uses angular ball bearings, and the two bearings 53a and 53b are installed in a back-to-back combination (DB combination).

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. The stator 9 of the generator G is fixed between the first outer ring spacer 54g1 and the second outer ring spacer 54g2. The 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 between them. 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 is also possible.

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 and S poles 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.

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

The outer ring spacer 54g and the stator 9 are thermally insulated by the heat insulating portion 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, 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.

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 the 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. The ends 15a and 15b of the coil 15 are connected to the circuit board 10 through the hole 71a1 of the first heat insulating part 71a and the hole 54g1b of the first outer ring spacer 54g1. It is preferable to seal the holes 71a1 and 54g1b with a sealant after wiring to prevent oil and the like from entering the circuit board 10 side.

The AC power output from the electric machine G by the rotation of the main shaft 51 is converted to DC by the power supply circuit 16. The cover 73, which serves 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 the bearing device 90 may be configured such that the inside of the groove 54g1a, including the circuit board 10, is sealed with a resin molding material instead of the cover 73.

Sensors 17, such as a temperature sensor 18, an acceleration sensor 19, and a load sensor 21, are implemented as necessary. The output of each sensor is wirelessly transmitted to the outside using a wireless communication circuit 20.

The single-row rolling bearing 55 is a cylindrical roller bearing. The angular ball bearings 53a and 53b support the 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.

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 lubricating oil supply path is required, but if lubrication with air oil or the like is required, a lubricating oil supply path is provided in the outer ring spacer 54g. Note that the lubricating oil supply path is not shown here.

During assembly, first the front cover 60, bearing 53a, spacer 54, bearing 53b, and spacer 58 are inserted into the main shaft 51 in that order, and an initial preload is applied by tightening the nut 59. After that, the main shaft 51 with the bearings 53a and 53b attached is inserted into the housing 57 until the right side of the outer ring 53gb of the bearing 53b in FIG. 9 hits the stepped portion 57a provided on the housing 57. Finally, the front cover 60 presses the outer ring 53ga of the left bearing 53a, fixing the main shaft 51 to the housing 57.

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 towards the inner ring spacer 54i. This force is transmitted through the inner ring 53ib, the rolling element 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 element Tb, and is also transmitted from the outer ring 53gb to the outer ring spacer 54g.

This force is transmitted to the outer ring 53ga, rolling element Ta, and inner ring 53ia in the bearing 53a, and also applies preload 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.

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 retainer 62. The inner ring retainer 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 against the end member 64 in response to the expansion and contraction of the main shaft 51.

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

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 placed 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, so that the operating status of the spindle device 50 can be monitored. The bearing device 90 may determine the presence or absence of anomalies from the output of each sensor within the circuit board 10 and transmit the determination results wirelessly.

In order to allow the 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 rolling element Ta of the bearing 53 is made of ceramic, which is an insulator, and that the retainer Rta is made of resin, which is an insulator. The radio waves are then released to the outside through the gap 70 in the labyrinth seal formed by 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 for the radio wave environment. If the radio waves are directional, it is recommended to provide a wireless transmitter/receiver or repeater (not shown) below the main shaft.

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 section 71. Therefore, in the bearing device 90, the 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 allows for more accurate detection of 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 assembly.

[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 cars. 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.

Vertical take-off and landing aircraft (VTOL) have been attracting attention as flying cars. Vertical take-off and landing aircraft 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 social demands for reducing _CO2 emissions, electric vertical take-off and landing aircraft (eVTOL), which fly using batteries and motors, have become the mainstream of development.

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 equipped with the bearing device 1 of embodiment 1 will be described as an example with reference to FIG. 10.

As shown in FIG. 10, the electric vertical take-off and landing aircraft 101 is a multicopter having a main body 102 located in the center of the aircraft, and four drive units 103 arranged in the front, back, left and right directions. The drive units 103 are devices that generate lift and thrust for the electric vertical take-off and landing aircraft 101. The electric vertical take-off and landing aircraft 101 flies due to the driving of the drive units 103. The electric vertical take-off and landing aircraft 101 may have multiple drive units 103, and is not limited to four.

The main body 102 has a living space that can accommodate a crew member (for example, one or two people). This living space is equipped with an operating system for determining the direction of travel and altitude, and instruments that indicate altitude, speed, flight position, etc. 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 to protect the rotor 104 is integrally provided on the arm 102a. In addition, a skid 102b that supports the aircraft when it lands is provided at the bottom of the main body 102.

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 that extend radially outward.

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.

When the bearing device 90 of the second modified example 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 the stator 69 fixed to the cylindrical member 61, and is rotatable relative to the stator 69. The motor device 105 can be configured as an outer rotor type brushless motor or an inner rotor type brushless motor.

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, 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, 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 or CFRP (carbon fiber reinforced plastic).

When the motor device 105 is used in the bearing device 90, the bearing device 90 rotatably supports the 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 transferred to the outer ring spacer 54g. A groove 54g1a is formed on the 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 the 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.

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 that supports the rotating shaft in the drive unit may be the bearing device that supports the rotating shaft of the motor device 105, or may be the bearing device that supports the rotating shaft of the rotor.

(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.

By providing such a configuration, the stator 9 and bearing B of the generator G are thermally insulated by the insulating section 11, so that the heat transfer of heat due to 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 a 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 a 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.

Preferably, the rotor further includes a heat dissipation section 12a that is arranged to abut against the stator 9 and is made of a material with high thermal conductivity, and a heat insulating layer 12b that is arranged on the outer peripheral surface of the heat dissipation section 12a and is made of a heat insulating material with low thermal conductivity. The heat insulating layer 12b abuts against the outer ring 7.

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, while the insulating layer 12b prevents the temperature of the heat dissipation section 12a from being directly transferred to the outer ring 7, thereby preventing heat generated by the stator 9 from affecting the bearing B.

Preferably, one of the outer ring 2 and 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 the space formed between the end face of the outer ring 7 that abuts against the end face of the stationary ring and the partition wall 11a of the heat insulating section 11.

With this configuration, the circuit board 10 is positioned 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 associated with the rotation of the bearing B can be accurately measured.

Preferably, the wireless communication circuit 20 includes an antenna portion 20a therein. The antenna portion 20A is arranged in a position that does not overlap with the stator 9 in the axial direction, and is arranged in a position facing the heat insulating portion 11.

By having such a configuration, the antenna part 20a can transmit radio waves outside the bearing device 1 without being affected by conductive materials such as metals.

Preferably, the bearing device 1A has a cutout portion 11Ad formed in part of the outer periphery of the heat insulating portion 11A and 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 disposed within the area of the cutout portion 11Ad.

By adopting this configuration, the bearing device 1A can be configured so that the stator 9A is positioned closer to the bearing B, thereby shortening the axial width of the outer ring 7 and enabling miniaturization.

Preferably, in the bearing device 90, the outer ring spacer 54g serves as the fixed member.
By being configured as described above, the bearing device 90 can accurately measure the temperature rise or acceleration that accompanies the rotation of the bearing 53 in a configuration including the bearings 53a and 53b.

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

By having such a configuration, 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.

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.

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.

By using this configuration, the temperature rise or acceleration caused by the rotation of the bearings in the electric vertical take-off and landing aircraft 101 can be accurately measured.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is indicated by the claims rather than the description of the embodiments above, and is intended to include all modifications within the meaning and scope of the claims.

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 Cage, 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 part, 10 Circuit board, 11, 11A, 71 Heat insulation part, 11Aa, 11a Partition, 11Ad Notch part, 12, 73 Lid, 12a, 72 Heat dissipation part, 12b Heat insulation layer, 13, 13A Magnetic ring member, 14 Bobbin, 15 Coil, 16 Power supply circuit, 17 Sensor, 18 Temperature sensor, 19 acceleration sensor, 20 wireless communication circuit, 20a antenna unit, 50 spindle device, 51 main shaft, 54g outer ring spacer, 54i inner ring spacer, 60 front cover, 71a first insulation part, 71b second insulation part, G generator.

Claims (9)

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. 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. 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. 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. 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. The bearing device according to claim 1 or 2, wherein the fixing member is an outer ring spacer. 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. A spindle device equipped with a bearing device according to any one of claims 1 to 7. 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.

Images