Claw-pole type generator, bearing with sensor, and spindle device

Abstract

In a claw-pole type generator in which a stator having an arc-shaped yoke structure and a rotor having alternating north and south poles in the circumferential direction are radially opposed, the change in the yoke structure over time is suppressed. [Solution] The yoke structure 3 is formed of two or more first magnetic material members 7 arranged in the circumferential direction, and two or more second magnetic material members 8 arranged in the circumferential direction at positions facing the first magnetic material members 7 in the axial direction. Each first magnetic material member 7 and each second magnetic material member 8 integrally has a circumferential portion of the first side 3a or second side 3b and one axial side portion of the first claw pole portion 3c or second claw pole portion 3d and connecting portion 3e extending from there in the axial direction.

Description

Technical Field

[0001] The present invention relates to a claw-pole generator, a bearing with a sensor comprising the same, and a spindle device, and in particular to a yoke structure of a stator of a claw-pole generator. Background Art

[0002] Conventionally, it has been practiced to provide required sensors such as temperature sensors and strain sensors for detecting the state of rolling bearings and spindle devices, a wireless module for transmitting measurement results of the sensors, and a claw-pole generator for wirelessly driving these sensors and the wireless module together.

[0003] These sensors, wireless modules and the like are mounted on a circuit board. A sensor unit holding this circuit board and a stator of the claw-pole generator are arranged on the stationary side. On the other hand, a rotor of the claw-pole generator is arranged on the rotating side. The rotor has N poles and S poles alternately in the circumferential direction. The stator has a yoke structure provided in an arc shape on the radially outer side of the rotor, and a coil. The yoke structure has a pair of side portions axially opposed to each other, claw pole portions arranged at predetermined intervals in the circumferential direction between one radial end sides of the pair of side portions, and a connecting portion extending axially between the other radial end sides of the pair of side portions. The claw pole portions arranged in the circumferential direction are alternately connected continuously to the side portion on one axial side or the side portion on the other axial side in the circumferential direction. The yoke structure is constituted by one first magnetic member and one second magnetic member. The first magnetic member has the side portion on one axial side, the claw pole portion continuous therewith, and one axial side of the connecting portion. The second magnetic member has the side portion on the other axial side, the claw pole portion continuous therewith, and the other axial side of the connecting portion. The coil is arranged along the yoke structure. Winding ends at both ends of the coil are connected to the circuit board. An alternating magnetic field accompanying rotation of the rotor is converted into alternating-current power by the stator. The alternating-current power is converted into direct-current power by a power supply circuit on the circuit board and supplied to the sensor and the wireless module (for example, Patent Documents 1 to 3).

[0004] In this type of claw-pole generator, a yoke structure provided around the entire circumference (hereinafter referred to as an annular yoke structure) or a yoke structure provided for a finite length around the circumference (hereinafter referred to as an arc-shaped yoke structure) is selected, taking into consideration the amount of installation space available for arranging the stator and circuit board, the required power generation capacity, etc. An arc-shaped yoke structure is suitable, for example, when it is desirable to arrange the stator and circuit board on the same circumference and reduce the axial width required for their arrangement (for example, Patent Document 3). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-156079 [Patent Document 2] Japanese Patent Publication No. 2021-127831 [Patent Document 3] Japanese Patent Publication No. 2023-147974 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the arc-shaped yoke structure disclosed in Patent Document 3 is more susceptible to changes over time compared to the annular yoke structure, and there are concerns that it may become elliptical due to the discontinuation at one point in the circumferential direction, negatively affecting the amount of power generated. In other words, in the case of an annular yoke structure, it is not inherently prone to becoming elliptical over time, but even if it does become elliptical, the change in power generation due to the change in the air gap near the major axis of the yoke structure and the change in power generation due to the reverse change in the air gap near the minor axis of the yoke structure are roughly equal, so these changes cancel each other out. On the other hand, in the case of an arc-shaped yoke structure, if it becomes elliptical over time, the discontinuation in the circumferential direction of the yoke structure causes an imbalance between the changes near the major axis and the changes near the minor axis, and these changes do not cancel each other out.

[0007] Therefore, the problem that this invention aims to solve is to suppress changes in the yoke structure over time in a claw-pole type generator in which a stator having an arc-shaped yoke structure and a rotor having alternating north and south poles in the circumferential direction are radially opposed. [Means for solving the problem]

[0008] To solve the above problems, this invention provides a rotor having alternating north and south poles in the circumferential direction, and a stator that converts the alternating magnetic field generated by the rotation of the rotor into alternating power, wherein the stator has a yoke structure provided in an arc shape on the radially outer side of the rotor, and a coil, wherein the yoke structure is formed of a pair of sides facing each other in the axial direction, a first claw pole portion projecting in the axial direction from the radially inner side of the first side, a second claw pole portion projecting in the axial direction from the radially inner side of a second side different from the first side, and a connecting portion connecting the radially outer side of the first side and the radially outer side of the second side, wherein the first claw pole portion and the second claw pole portion are arranged alternately in the circumferential direction, and the coil passes between the pair of sides in the circumferential direction. A claw-pole type generator having a first coil portion and a second coil portion passing circumferentially on the radially outer side of the connection portion, wherein the yoke structure is formed of two or more first magnetic material members arranged in the circumferential direction and two or more second magnetic material members arranged in the circumferential direction at a position facing the first magnetic material members in the axial direction, and each of the first magnetic material members integrally has a circumferential portion of the first side and the first claw-pole portion and the first one-sided portion of the connection portion extending axially from this circumferential portion, and each of the second magnetic material members integrally has a circumferential portion of the second side and the second claw-pole portion and the second one-sided portion of the connection portion extending axially from this circumferential portion, characterized in that a claw-pole type generator is adopted.

[0009] The changes in the first magnetic material member and the second magnetic material member over time depend on their respective circumferential lengths (the longer they are circumferentially, the greater the change in the radial direction). According to the above configuration 1, the arc-shaped yoke structure is divided into multiple sections in the circumferential direction, and the first magnetic material member and the second magnetic material member, which are the dividing elements, are provided to be short in the circumferential direction. As a result, the changes in each of them over time are reduced, and consequently, it becomes possible to suppress the changes in the yoke structure over time.

[0010] In the above configuration 1, configuration 2 can be adopted in which the first magnetic material member and the second magnetic material member are each made of pressed iron plate parts.

[0011] The springback that occurs immediately after press bending of sheet metal depends on the circumferential length of each component (the longer the circumferential length, the greater the radial springback). According to configuration 2 described above, since the first and second magnetic material components, which are short in the circumferential direction, are press-formed as described above, the springback of each of the first and second magnetic material components becomes smaller, and consequently, the dimensional control of each component as a press-formed part becomes easier.

[0012] In the above configuration 1 or 2, configuration 3 can be adopted, in which the central angle of the first magnetic material member extending in an arc shape and the central angle of the second magnetic material member extending in an arc shape are each set to 30° or more and 45° or less.

[0013] According to the above configuration 3, it becomes possible to suppress changes over time in the first magnetic material member and the second magnetic material member, as well as springback when they are made into pressed parts, while also reducing the effort required to assemble the yoke structure.

[0014] Furthermore, a configuration 4 can be adopted in which a claw-pole type generator comprising a first raceway, a second raceway radially opposite to the first raceway, a plurality of rolling elements arranged between the first raceway and the second raceway, a sensor unit fixed to the first raceway, and any one of the above configurations 1 to 3, wherein the rotor is fixed to the second raceway, and the sensor unit is a sensor-equipped bearing having a power supply circuit that converts the AC power to DC power, a sensor, and a wireless communication circuit.

[0015] Furthermore, a spindle device configuration 5 can be adopted, comprising a spindle of a machine tool, a housing, a first rolling bearing, a second rolling bearing, an inner ring spacer, an outer ring spacer, and a claw-pole type generator having any one of the above configurations 1 to 3, wherein the first rolling bearing and the second rolling bearing each have an inner ring fitted to the spindle, an outer ring fitted to the housing, and a plurality of rolling elements arranged between the corresponding inner rings and the corresponding outer rings, the inner ring spacer is arranged between the inner ring of the first rolling bearing and the inner ring of the second rolling bearing, the outer ring spacer is arranged between the outer ring of the first rolling bearing and the outer ring of the second rolling bearing, the rotor is fixed to the inner ring spacer, and the stator is fixed to the outer ring spacer. [Effects of the Invention]

[0016] As described above, by adopting the above configuration 1, this invention makes it possible to suppress changes in the yoke structure over time in a claw-pole type generator in which a stator having an arc-shaped yoke structure and a rotor having alternating north and south poles in the circumferential direction are radially opposed. [Brief explanation of the drawing]

[0017] [Figure 1] Front view showing a claw-pole type generator according to an embodiment of this invention. [Figure 2] Cross-sectional view of line II-II shown in Figure 1 [Figure 3] Exploded perspective view of the yoke structure and bobbin according to the embodiment. [Figure 4] A perspective view showing the first magnetic members extracted from FIG. 3 and arranged in the circumferential direction [Figure 5] A cross-sectional view showing a bearing with a sensor according to an embodiment of the present invention [Figure 6] A side view showing the right side surface of the bearing with a sensor of FIG. 5 with a cover of the sensor unit removed [Figure 7] A cross-sectional view showing a spindle device according to an embodiment of the present invention MODE FOR CARRYING OUT THE INVENTION

[0018] A claw-pole generator according to an exemplary embodiment of the present invention (hereinafter simply referred to as "this claw-pole generator") will be described with reference to FIGS. 1 to 4 of the accompanying drawings.

[0019] This claw-pole generator is configured such that a stator 1 is fixed to a stationary member (not shown), a rotor 2 is fixed to a rotating member (not shown), and the rotational movement of the rotor 2 relative to the stator 1 is electromagnetically converted into AC power.

[0020] Herein, a direction along the rotation center axis of the rotor 2 is referred to as "axial direction", a direction orthogonal to the rotation center axis is referred to as "radial direction", and a direction along a circumference centered on the rotation center axis is referred to as "circumferential direction".

[0021] The rotor 2 is a rotor having N poles and S poles alternately in the circumferential direction. The stator 1 is a stator that guides magnetic flux emitted from the rotating rotor 2 with a yoke structure 3 to generate an alternating magnetic field, and induces an AC voltage in a coil 4 by the alternating magnetic field. The stator 1 and the rotor 2 are arranged with a predetermined coaxiality. It should be noted that each drawing is drawn on the premise of an ideal state where the stator 1 and the rotor 2 are arranged concentrically.

[0022] The rotor 2 is formed in an annular shape by a multi-pole magnetized magnet 5 and a core bar 6 that supports the magnet 5 in the radial direction. The magnet 5 is formed of magnetic rubber extending in the circumferential direction. The magnet 5 is bonded to the core bar 6.

[0023] The yoke structure 3 is provided in an arc shape on the radially outer side of the rotor 2 (the side farther from the rotational axis of the rotor 2), and together with the rotor 2, magnetically forms a series of magnetic circuits in a range of less than 360° in the circumferential direction. The yoke structure 3 is formed of a pair of sides 3a and 3b that face each other in the axial direction, a number of first claw poles 3c that project in the axial direction from the radially inner side (the side closer to the rotational axis of the rotor 2) of the first side 3a, which is one of the pair of sides 3a and 3b, a number of second claw poles 3d that project in the axial direction from the radially inner side of the second side 3b, which is the side different from the first side 3a of the pair of sides 3a and 3b, and a connecting part 3e that connects the radially outer side of the first side 3a and the radially outer side of the second side 3b. The first claw poles 3c and the second claw poles 3d are arranged alternately in the circumferential direction. Furthermore, the first claw pole section 3c and the second claw pole section 3d are positioned in opposite directions in the axial direction. In the figures, of the pair of side sections 3a and 3b, the one located on one axial side (right side in Figures 2 and 3) is the first side section 3a, and the one located on the other axial side (left side in Figures 2 and 3) is the second side section 3b. Therefore, the first claw pole section 3c protrudes from the first side section 3a to the other axial side (left side in Figures 2 and 3), and the second claw pole section 3d protrudes from the second side section 3b to one axial side (right side in Figures 2 and 3).

[0024] The coil 4 is arranged around the connecting portion 3e such that it has a first coil portion 4a that passes circumferentially between a pair of side portions 3a and 3b, and a second coil portion 4b that passes circumferentially on the radially opposite end side to the connecting portion 3e.

[0025] As shown in Figures 3 and 4, the yoke structure 3 is divided into two parts in the axial direction and into multiple parts in the circumferential direction. The stator 1 has two or more first magnetic members 7 and second magnetic members 8, which are components of the yoke structure 3. All of these first magnetic members 7 are arranged in a circumferential direction. All of these second magnetic members 8 are arranged in a circumferential direction at a position facing the first magnetic members 7 in the axial direction.

[0026] The first magnetic member 7 and the second magnetic member 8 are each made from pressed parts using iron plates as the material. Therefore, the entirety of the first magnetic member 7 and the entirety of the second magnetic member 8 are formed without any seams.

[0027] As shown in Figures 2, 3, and 4, the first magnetic member 7 integrally comprises a circumferential portion 3aS of the first side portion 3a and a first claw pole portion 3c and a first one-sided portion 3eRS of the connecting portion 3e that extend axially from this circumferential portion 3aS. The circumferential portion 3aS of the first side portion 3a extends radially and circumferentially. The first claw pole portion 3c and the first one-sided portion 3eRS of the connecting portion 3e are each bent to protrude axially from the circumferential portion 3aS to the other side.

[0028] The second magnetic member 8 integrally comprises a circumferential portion 3bS of the second side portion 3b, and a second claw pole portion 3d and a second one-sided portion 3eLS of the connecting portion 3e, which extend axially from this circumferential portion 3bS. The circumferential portion 3bS of the second side portion 3b extends radially and circumferentially so as to be axially opposite to the circumferential portion 3aS of the first side portion 3a. The second claw pole portion 3d and the second one-sided portion 3eLS of the connecting portion 3e are each bent so as to protrude axially from the circumferential portion 3bS to one side.

[0029] As shown in Figures 3 and 4, the first magnetic member 7 is bent into an arc shape overall. One end and the other end of the first magnetic member 7 in the circumferential direction are shaped along the radial direction, and can be butted circumferentially with the other end or one end of an adjacent first magnetic member 7 with virtually no gap. Similarly, both ends of the second magnetic member 8, which is also arc-shaped, are shaped along the radial direction.

[0030] The central arc angle of each first magnetic material member 7 and the central arc angle of each second magnetic material member 8 are set to be the same. Therefore, the total number of first magnetic material members 7 and the total number of second magnetic material members 8 constituting the yoke structure 3 are the same.

[0031] As shown in Figure 2, the first side portion 3eRS and the second side portion 3eLS of the connecting portion 3e are abutted against each other in the axial direction at their respective ends. To facilitate the circumferential phase alignment of the first magnetic member 7 and the second magnetic member 8 during this abutment, the first magnetic member 7 has two first side portions 3eRS of the connecting portion 3e in the circumferential direction, and the second magnetic member 8 has two second side portions 3eLS of the connecting portion 3e in the circumferential direction. The slits between these two first side portions 3eRS and the slits between these two second side portions 3eLS are formed to serve as markers for the aforementioned phase alignment.

[0032] The coil 4 is wound on an arc-shaped bobbin 9, as shown in Figures 2 and 3. The arc-shaped bobbin 9 has a slit portion 9a that penetrates axially at the midpoint of its radial width. The slit portion 9a is formed in an arc shape with a circumferential length and radial width that allows all of the first side portions 3eRS and second side portions 3eLS, which are dividing elements of the connecting portion 3e, to be inserted axially. The first side portions 3eRS and second side portions 3eLS of the connecting portion 3e, which are facing each other in the axial direction, are abutted axially within the slit portion 9a so as to magnetically connect the radially outer side of the first side portion 3a and the radially outer side of the second side portion 3b. The radially inner end of the arc-shaped bobbin 9 is a groove portion that accommodates the first coil portion 4a, and the radially outer end of the arc-shaped bobbin 9 is a groove portion that accommodates the second coil portion 4b. The entire arc-shaped bobbin 9 is made of resin.

[0033] The arc-shaped bobbin 9 and each of the first magnetic material members 7 and each of the second magnetic material members 8 are bonded together, and this bonding integrates the arc-shaped bobbin 9 with the coil 4 wound around it with the assembly of the yoke structure 3. Furthermore, to protect the coil 4 for insulation, heat resistance, dustproofing, moisture resistance, and abrasion prevention purposes, a varnish treatment may be employed, which involves dipping the coil 4 in varnish or coating it by dripping varnish onto it. Alternatively, the arc-shaped bobbin 9 can be omitted, and an insulated coil can be used, with the insulated coil directly wound around the connection portion 3e of the assembled yoke structure 3.

[0034] The first claw pole section 3c and the second claw pole section 3d face each other radially with a radial air gap between them and the magnet 5. There is a circumferential air gap between the first claw pole section 3c and the second claw pole section 3d that are adjacent in the circumferential direction. The total number of first claw pole sections 3c and second claw pole sections 3d included in the yoke structure 3 is the same as the number of poles of the magnet 5 (total number of north and south poles).

[0035] The magnetic flux emanating from the north pole of magnet 5, for example, enters the first side portion 3a (or second side portion 3b) from the first claw pole portion 3c (or second claw pole portion 3d), which is the magnetic pole, and then circulates around the first coil portion 4a of coil 4, passing through the connection portion 3e and returning to the second side portion 3b (or first side portion 3a), before passing through the adjacent second claw pole portion 3d (or first claw pole portion 3c) and returning to the south pole of magnet 5. As the rotor 2 rotates, the positions of the north and south poles of magnet 5 are reversed, and the direction of the magnetic flux is reversed. The alternating magnetic field generated in this way causes an alternating voltage to be generated at both ends of the coil 4, at the beginning and end of the winding.

[0036] The closer the central angle of the arc-shaped yoke structure 3 is to 360°, the greater the number of magnetic poles of the magnet 5 facing the yoke structure 3 in the radial direction, and the greater the amount of electricity generated. From the viewpoint of power generation, it is best to set the central angle of the arc-shaped yoke structure 3 to as large an angle as possible, for example, at least 90° or more, preferably 180° or more.

[0037] When a long, arc-shaped yoke structure in the circumferential direction is constructed using one first magnetic material member and one second magnetic material member, the changes over time and springback immediately after press working of both magnetic material members become large, which is disadvantageous for dimensional control during manufacturing and for maintaining power generation during use. It is known that the changes over time and springback immediately after press working of metal materials such as arc-shaped iron plates depend on the central angle of the arc of the metal material (the bending angle determined by the central angle of the arc when press working) and the radius of the arc (the bending radius determined by the radius of the arc when press working). Therefore, in an arc-shaped magnetic material member having an arbitrary radius of the arc (bending radius), shortening its overall length in the circumferential direction makes it possible to reduce the central angle of the arc (bending angle) and thus reduce the changes over time and springback of the magnetic material member.

[0038] On the other hand, if the overall length of the magnetic material members in the circumferential direction is made excessively short, the total number of first and second magnetic material members required to construct a yoke structure that is long in the circumferential direction will increase, resulting in a greater amount of time and effort being spent assembling the yoke structure.

[0039] Therefore, in this claw-pole type generator, considering the suppression of changes over time and springback of each first magnetic material member 7 and each second magnetic material member 8 constituting the yoke structure 3, as well as the ease of assembly of the yoke structure 3, the central angles of the arcs of the first magnetic material members 7 and the central angles of the arcs of the second magnetic material members 8 are set to be between 30° and 45°. In the illustrated example, the central angles of the arcs of the first magnetic material members 7 and the central angles of the arcs of the second magnetic material members 8 are each set to 36°, and the yoke structure 3 is assembled with eight first magnetic material members 7 and eight second magnetic material members 8, with a central angle of 288°.

[0040] Thus, the changes over time and springback that occur in each of the first magnetic members 7 and each of the second magnetic members 8, which are shorter in the circumferential direction, are significantly smaller compared to when the yoke structure is composed of one first magnetic member and one second magnetic member. As a result, the elliptotic deformation and dimensional errors due to springback caused by changes over time in the yoke structure 3 as a whole are also significantly reduced. Consequently, the difference between the change in power generation in the angular region where the radial air gap between the yoke structure 3 and the magnet 5 is small and the change in power generation in the angular region where the radial air gap is large becomes smaller.

[0041] This claw-pole type generator (see Figures 1-3) is as described above and comprises a rotor 2 having alternating north and south poles in the circumferential direction, and a stator 1 that converts the alternating magnetic field generated by the rotation of the rotor 2 into alternating current power. The stator 1 has a yoke structure 3 provided in an arc shape on the radially outer side of the rotor 2, and a coil 4. The yoke structure 3 has a pair of side portions 3a and 3b facing each other in the axial direction, a first claw-pole portion 3c protruding axially from the radially inner side of the first side portion 3a, and the first side portion 3 The coil 4 is formed by a second claw pole portion 3d that protrudes axially from the radially inner side of a second side portion 3b which is different from a, and a connecting portion 3e that connects the radially outer side of the first side portion 3a and the radially outer side of the second side portion 3b, with the first claw pole portion 3c and the second claw pole portion 3d arranged alternately in the circumferential direction, and the coil 4 has a first coil portion 4a that passes circumferentially between the pair of side portions 3a and 3b, and a second coil portion 4b that passes circumferentially on the radially opposite end of the connecting portion 3e.

[0042] This claw pole type generator is formed by a yoke structure 3 consisting of two or more first magnetic members 7 arranged circumferentially, and two or more second magnetic members 8 arranged circumferentially at positions axially opposite to the first magnetic members 7, and each first magnetic member 7 integrally has a circumferential portion 3aS of the first side 3a and a first claw pole portion 3c and a first side portion 3eRS of the connecting portion 3e extending axially from this circumferential portion 3aS, and each second magnetic member 8 is second By integrally having a circumferential portion 3bS of the side portion 3b and a second claw pole portion 3d and a second side portion 3eLS of the connecting portion 3e that extend axially from this circumferential portion 3bS, the arc-shaped yoke structure 3 becomes a structure in which multiple divisions are made in the circumferential direction. Since the first magnetic material member 7 and the second magnetic material member 8, which are the dividing elements, are each provided to be short in the circumferential direction, their changes over time are reduced, and consequently, changes over time of the yoke structure 3 can be suppressed.

[0043] Furthermore, in this claw-pole type generator, since the first magnetic member 7 and the second magnetic member 8 are each made from pressed iron plates, the first magnetic member 7 and the second magnetic member 8, which are short in the circumferential direction, are pressed, which reduces the springback of the first magnetic member 7 and the second magnetic member 8, and consequently makes it easier to control the dimensions of each as a pressed part.

[0044] Furthermore, in this claw-pole type generator, the central angles of the first magnetic member 7 and the second magnetic member, which extend in an arc shape, are set to 30° or more and 45° or less, thereby suppressing changes over time in the first magnetic member 7 and the second magnetic member 8, as well as springback when they are made into pressed parts, while also reducing the effort required to assemble the yoke structure 3.

[0045] Figures 5 and 6 show a sensor-equipped bearing (hereinafter referred to as "this sensor-equipped bearing") as an example embodiment of this invention.

[0046] This sensor-equipped bearing comprises a rolling bearing 10, a sensor unit 20, and this claw-pole type generator.

[0047] The rolling bearing 10 includes a first raceway ring 11, a second raceway ring 12 radially opposite to the first raceway ring 11, a plurality of rolling elements 13 positioned between the first raceway ring 11 and the second raceway ring 12, and a cage 14 that holds these rolling elements 13.

[0048] The first raceway ring 11 is fixed to a rotating shaft (not shown) and rotates relative to the second raceway ring 12 in the circumferential direction. The first raceway ring 11 is configured as an inner ring with a raceway 11a on its outer circumference.

[0049] The second raceway 12 is fitted into a housing (not shown) and is a component that rests relative to the first raceway 11. The second raceway 12 is configured as an outer ring with a raceway 12a on its inner circumference.

[0050] The rolling bearing 10 is a radial bearing. Furthermore, the rolling bearing 10 is a standard bearing conforming to a specific standard. Here, a standard bearing refers to a bearing that satisfies the dimensions specified in the ISO standard or the JIS standard. For example, the dimensions of radial bearings other than tapered roller bearings are specified in ISO 15 or JIS B 1512-1.

[0051] Although the example given shows the rolling bearing 10 as a deep groove ball bearing, the rolling bearing 10 is not limited to a deep groove ball bearing.

[0052] The rotor 2 and the sensor unit 20, which is integrated with the yoke structure 3, are positioned between the outer circumference end 11b of the first raceway 11 and the inner circumference end 12b of the second raceway 12. These outer circumference end 11b and inner circumference end 12b are stepped and recessed radially away from each other in order to secure space for the installation of the rotor 2 and the sensor unit 20.

[0053] The rotor 2 is fixed to the outer circumference end 11b of the first raceway ring 11. The sensor unit 20 is fixed to the inner circumference end 12b of the second raceway ring 12. These fixings can be done by appropriate means such as press-fitting. Neither the sensor unit 20 nor this claw-pole type generator protrudes from the rolling bearing 10 in one axial direction (the side furthest from the rolling elements 13 in the axial direction).

[0054] The sensor unit 20 includes a sensor holder 22 that holds the substrate 21, a sensor 23 mounted on the substrate 21, a wireless communication circuit 24 and a power supply circuit 25, and a cover 26 attached to the sensor holder 22. The substrate 21, sensor 23, wireless communication circuit 24 and power supply circuit 25 constitute a circuit board in which each element is mounted on one side of the substrate in the axial direction.

[0055] The sensor unit 20 converts the AC power generated at both ends 4c of the coil of the stator 1 into DC power using the power supply circuit 25, and uses this DC power to drive a sensor 23 that detects at least one of a physical quantity and a chemical quantity related to the state of the rolling bearing 10, and can wirelessly transmit the detection result to the outside using the wireless communication circuit 24.

[0056] Sensor 23 is, for example, an acceleration sensor that detects radial and axial acceleration to monitor vibrations of the rolling bearing 10, or a temperature sensor to monitor the temperature of the rolling bearing 10.

[0057] The wireless communication circuit 24 consists of a communication circuit that converts predetermined information, such as detection results from the sensor 23, into radio waves and radiates them from the antenna. The wireless communication circuit 24 conforms to a predetermined communication protocol and is generally a module.

[0058] Alternatively, the sensor holder may house a battery, and the output of this claw-pole generator may be used to charge the battery, or in the event of an emergency where power generation by the claw-pole generator is insufficient or stops, the DC power from the battery may be supplied to the power supply circuit 25 and converted into DC power corresponding to the sensor 23, etc.

[0059] The sensor holder 22 is constructed as a metal ring having an outer diameter wall portion extending around the entire circumference, an inner diameter wall portion extending in an arc shape, and an annular side wall portion extending from the outer diameter wall portion to one radial end (the side closer to the rotor 2 in the radial direction). The inner diameter wall portion, a portion of the outer diameter wall portion in the circumferential direction, and a portion of the annular side wall portion in the circumferential direction of the sensor holder 22 form a groove portion for housing the circuit board, while the remaining portion of the outer diameter wall portion and the remaining portion of the annular side wall portion form an angle wall portion that supports the stator 1 from the other radial end (the side farther from the rotor 2 in the radial direction) and the other axial side (the side closer to the rolling element 13 in the axial direction). Such a sensor holder 22 can be formed by press working using steel plate or the like as the material.

[0060] The cover 26 is fitted to the outer diameter wall of the sensor holder 22 and the yoke structure 3 so as to cover the aforementioned groove and the portion of the stator 1 other than the yoke structure 3 from one axial side.

[0061] The yoke structure 3 and the sensor holder 22 can be fixed by appropriate means such as screws or adhesive. Insulation between the substrate 21 and the sensor holder 22 can be provided by placing an insulating sheet or the like as appropriate. The cover 26 only needs to be capable of transmitting radio waves to accommodate the aforementioned wireless communication. Furthermore, any gaps in the sensor unit 20 may be filled with sealing material as appropriate.

[0062] Furthermore, while this sensor-equipped bearing example shows the second raceway ring as the stationary outer ring, it is also possible to change the specification to one where the outer ring is the rotating ring and the inner ring is the stationary ring, with the sensor unit mounted on the stationary inner ring and the rotor mounted on the rotating outer ring. In this case, all that is required is to reverse the radial orientation in which the sensor unit and rotor are mounted.

[0063] The sensor unit 20 described above and this claw-pole type generator can also be applied to rotating devices other than rolling bearings; for example, the rotating member and mating member can be changed to members other than raceway rings. Figure 7 shows a spindle device (hereinafter referred to as "this spindle device") as an example embodiment of this invention. In the following, only the differences from the rotating devices shown in Figures 5 and 6 will be described.

[0064] This spindle device comprises a machine tool spindle 100, a housing 101 surrounding the spindle 100, a first rolling bearing 102, a second rolling bearing 103, an outer ring spacer 104, and an inner ring spacer 105.

[0065] The main shaft 100 also serves as the motor shaft. The housing 101 is a bearing housing with cooling passages. The inner diameter surface 106 of the inner ring spacer 105 is fitted onto the main shaft 100. The outer diameter surface 107 of the outer ring spacer 104 is fitted onto the inner diameter surface of the housing 101. The outer ring spacer 104 is provided with nozzles (not shown) that blow lubricating fluid supplied from the bearing housing side toward the first rolling bearing 102 and the second rolling bearing 103. The annular space 108 between the outer ring spacer 104 and the inner ring spacer 105 serves as a passage for the lubricating fluid.

[0066] The first rolling bearing 102 and the second rolling bearing 103 each have inner rings 109 and 110, outer rings 111 and 112, and a corresponding number of rolling elements 113 and 114 positioned between the corresponding inner rings 109 and 110 and the outer rings 111 and 112. The inner rings 109 and 110 are fitted onto the main shaft 100. The outer rings 111 and 112 are fitted onto the inner diameter surface of the housing 101.

[0067] The first rolling bearing 102 and the second rolling bearing 103 are angular contact ball bearings. The inner ring spacer 105 is positioned between the inner ring 109 and the inner ring 110, maintaining the axial span between these inner rings 109 and 110. The outer ring spacer 104 is positioned between the outer ring 111 and the outer ring 112, maintaining the axial span between these outer rings 111 and 112. The first rolling bearing 102 and the second rolling bearing 103 are subjected to an axial preload. The inner ring spacer 105 is a rotating member that rotates integrally with the main shaft 100, the inner rings 109 and 110. The outer ring spacer 104 is a mating member that is radially opposite to the inner ring spacer 105 as a rotating member. A load sensor 115 for estimating the aforementioned preload is attached to the axial middle portion of the inner circumference of the outer ring spacer 104. The load sensor 115 is, for example, a strain sensor.

[0068] The sensor unit 20, including the stator 1, is fixed to the inner circumference of the outer ring spacer 104. The rotor 2 is fixed to the outer circumference of the inner ring spacer 105. The load sensor 115 is electrically connected to the aforementioned circuit board of the sensor unit 20. The load sensor 115 is driven by DC power from the aforementioned power supply circuit, and the detection result of the load sensor 115 is also wirelessly transmitted by the aforementioned wireless communication circuit.

[0069] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications in the sense and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0070] 1 stater 2 rotors 3-Yoke Structure 3a, 3b side 3c, 3d Claw pole section 3e connection 4 coils 4a First coil section 4b Second coil section 5 Magnets 7. First magnetic material member 8. Second magnetic material member 9. Arc-shaped bobbin 10 Rolling bearings 11 First orbital ring 12. Second orbital ring 13 Rolling element 20 Sensor Units 21 circuit boards 22 Sensor holder 23 sensors 24 Wireless communication circuit 25 Power circuit 100 spindle 101 Housing 102 First rolling bearing 103 Second rolling bearing 104 Outer wheel spacer 105 Inner wheel spacer 109, 110 Inner Ring 111, 112 Outer ring 113, 114 Rolling elements 115 Load Sensor

Claims

1. The system comprises a rotor having alternating north and south poles in the circumferential direction, and a stator that converts the alternating magnetic field generated by the rotation of the rotor into alternating power. The stator has a yoke structure provided in an arc shape on the radially outer side of the rotor, and a coil. The yoke structure is formed of a pair of sides facing each other in the axial direction, a first claw pole portion projecting axially from the radially inner side of the first side, a second claw pole portion projecting axially from the radially inner side of a second side different from the first side, and a connecting portion connecting the radially outer side of the first side and the radially outer side of the second side. The first claw pole section and the second claw pole section are arranged alternately in the circumferential direction. In a claw-pole type generator, the coil has a first coil portion that passes circumferentially between the pair of side portions and a second coil portion that passes circumferentially on the radially outer side of the connecting portion, The yoke structure is formed of two or more first magnetic material members arranged in the circumferential direction, and two or more second magnetic material members arranged in the circumferential direction at positions facing the first magnetic material members in the axial direction. Each of the first magnetic members integrally comprises a circumferential portion of the first side and the first claw pole portion and the first side portion of the connecting portion extending axially from this circumferential portion. A claw-pole type generator characterized in that each of the second magnetic members integrally comprises a circumferential portion of the second side and the second claw-pole portion and the second one-sided portion of the connecting portion extending axially from the circumferential portion.

2. The claw pole type generator according to claim 1, wherein the first magnetic material member and the second magnetic material member are each made of pressed iron plate parts.

3. The claw-pole type generator according to claim 1 or 2, wherein the central angle of the first magnetic material member extending in an arc shape and the central angle of the second magnetic material member extending in an arc shape are each set to 30° or more and 45° or less.

4. The invention comprises a first raceway, a second raceway radially opposite to the first raceway, a plurality of rolling elements disposed between the first raceway and the second raceway, a sensor unit fixed to the first raceway, and the claw-pole type generator according to claim 1 or 2. The rotor is fixed to the second raceway ring, The sensor unit is a bearing with a sensor, comprising a power supply circuit that converts AC power to DC power, a sensor, and a wireless communication circuit.

5. The machine tool comprises a spindle, a housing, a first rolling bearing, a second rolling bearing, an inner ring spacer, an outer ring spacer, and the claw-pole type generator according to claim 1 or 2. The first rolling bearing and the second rolling bearing each have an inner ring fitted to the main shaft, an outer ring fitted to the housing, and a plurality of rolling elements arranged between the corresponding inner ring and the corresponding outer ring. The inner ring spacer is positioned between the inner ring of the first rolling bearing and the inner ring of the second rolling bearing. The outer ring spacer is positioned between the outer ring of the first rolling bearing and the outer ring of the second rolling bearing. The rotor is fixed to the inner ring spacer, A spindle device in which the stator is fixed to the outer ring spacer.

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