Rotation detector

Abstract

Provided is a rotation detector that facilitates proper power generation of a power generation element. A rotation detector (14) includes a pair of magnets (20), (22) that rotate with a rotary shaft, and a power generation element (24) that generates power by means of changes of a magnetic field caused by the pair of magnets (20), (22) rotating with the rotary shaft. The pair of magnets (20), (22) are arranged on both sides of a rotation axis A of the rotary shaft so as to be spaced apart in a first orthogonal direction, which is orthogonal to the rotation axis A. The N pole and the S pole of each of the pair of magnets (20), (22) are arranged along the first orthogonal direction such that the N pole is located on one side in the first orthogonal direction.

Description

[Technical Field]

[0001] The present disclosure relates to a rotation detector, and more particularly to a rotation detector that detects rotation of a rotating shaft. [Background technology]

[0002] Conventionally, rotation detectors that detect the rotation of a rotating shaft of a motor have been known. For example, Patent Document 1 discloses a rotation detector that includes a disk-shaped magnet attached to a shaft and three power generating units each composed of a magnetic wire and a pickup coil, with the three power generating units being arranged on each of the sides of an imaginary triangle formed on the end face side of the magnet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent No. 6336232 Summary of the Invention

[0004] However, the rotation detector of Patent Document 1 has a problem in that the distribution of magnetic flux density in the longitudinal direction of the power generating section is easily biased, making it difficult to generate electricity appropriately.

[0005] The present disclosure has been made to solve such problems, and aims to provide a rotation detector that makes it easy for a power generating element to generate electricity appropriately.

[0006] A rotation detector according to one aspect of the present disclosure includes a pair of magnets that rotate together with a rotation shaft, and a power generating element that generates power by utilizing changes in the magnetic field caused by the rotation of the pair of magnets together with the rotation shaft. The pair of magnets are arranged on either side of the rotation axis of the rotation shaft and spaced apart in a first orthogonal direction that is orthogonal to the rotation axis, and satisfies the following (1) or (2): (1) The north pole and south pole of each of the pair of magnets are aligned in the first orthogonal direction so that the north pole is located on one side in the first orthogonal direction. (2) The north and south poles of one of the pair of magnets are aligned in the direction of the rotation axis so that the north pole is located on one side in the direction of the rotation axis, and the north and south poles of the other of the pair of magnets are aligned in the direction of the rotation axis so that the north pole is located on the other side in the direction of the rotation axis.

[0007] According to the present disclosure, it is possible to provide a rotation detector that makes it easy for a power generating element to generate electricity appropriately. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a motor including a rotation detector according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating the rotation detector of FIG. [Figure 3] FIG. 3 is a diagram showing a pair of magnets of the rotation detector of FIG. [Figure 4] FIG. 4 is a diagram showing the relationship between the rotational position of the pair of magnets and the distribution of magnetic flux density in the longitudinal direction of the power generating element. [Figure 5] FIG. 5 is a diagram showing the relationship between the rotational position of the pair of magnets and the distribution of magnetic flux density in the longitudinal direction of the power generating element. [Figure 6] FIG. 6 is a diagram showing the relationship between the rotational position of the pair of magnets and the distribution of magnetic flux density in the longitudinal direction of the power generating element. [Figure 7] FIG. 7 is a diagram showing a rotation detector according to the second embodiment. [Figure 8] FIG. 8 is a diagram showing a rotation detector according to the third embodiment. [Figure 9] FIG. 9 is a diagram showing a rotation detector according to the fourth embodiment. [Figure 10] FIG. 10 is a diagram illustrating a rotation detector according to the fifth embodiment. [Figure 11] FIG. 11 is a diagram showing a rotation detector according to the sixth embodiment. [Figure 12] FIG. 12 is a diagram showing a rotation detector according to the seventh embodiment. [Figure 13A]FIG. 13A is a diagram showing another example of the magnet. [Figure 13B] FIG. 13B is a diagram showing still another example of the magnet. [Figure 14A] FIG. 14A is a diagram showing still another example of the magnet. [Figure 14B] FIG. 14B is a diagram showing still another example of the magnet. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, components, the arrangement and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the superordinate concept of the present disclosure will be described as optional components.

[0010] Furthermore, each figure is a schematic diagram and is not necessarily a precise illustration. In each figure, the same reference numerals are used to designate components that are substantially the same as those in other figures, and redundant explanations will be omitted or simplified.

[0011] (First embodiment) FIG. 1 is a diagram showing a motor 1 equipped with a rotation detector 14 according to a first embodiment. FIG. 2 is a diagram showing the rotation detector 14 of FIG. 1. FIG. 3 is a diagram showing a pair of magnets 20, 22 of the rotation detector 14 of FIG. 1. Note that FIG. 1 shows a cross section of the case 12 and the pair of magnets 20, 22. Also, FIG. 1 does not show the power generating element 26 and the control circuit 28.

[0012] As shown in Fig. 1, motor 1 includes a main body 4, a rotor 6, a stator 8, a rotating shaft 10, a case 12, and a rotation detector 14. In the following description, the rotation axis direction refers to the direction in which rotation axis A of rotating shaft 10 extends (the direction indicated by arrow X in Fig. 1).

[0013] The rotor 6 and the stator 8 are housed in the body 4. The rotor 6 rotates relative to the stator 8.

[0014] The rotating shaft 10 extends in the direction of the rotation axis and is rod-shaped, such as a cylindrical shape. The axial center of the rotating shaft 10 coincides with the rotation axis A. The rotating shaft 10 is fixed to the rotor 6 and rotates around the rotation axis A. For example, when power is supplied to the motor 1, the rotating shaft 10 rotates together with the rotor 6 around the rotation axis A based on the power. The rotation direction of the rotating shaft 10 (the direction indicated by arrow Z in FIG. 2 ) coincides with the circumferential direction centered on the rotation axis A. A rotation detector 14 is provided at one end of the rotating shaft 10 in the direction of the rotation axis. A load (not shown) that is rotationally driven by the rotation of the rotating shaft 10 is attached to the other end of the rotating shaft 10 in the direction of the rotation axis. For example, the rotating shaft 10 is formed of a magnetic metal such as iron.

[0015] The case 12 is attached to the main body 4 so as to cover one end of the rotating shaft 10 in the direction of the rotation axis and the rotation detector 14. For example, the case 12 is made of a magnetic metal such as iron.

[0016] The rotation detector 14 detects the rotation of the rotating shaft 10. For example, the rotation detector 14 detects the rotation position, rotation direction, and rotation speed of the rotating shaft 10. For example, the rotation detector 14 is an absolute encoder. As described above, the rotation detector 14 is provided at one end of the rotating shaft 10 in the direction of the rotation axis. As shown in FIGS. 1 and 2 , the rotation detector 14 has a rotating plate 16, a substrate 18, a pair of magnets 20, 22, a plurality of power generating elements 24, 26, and a control circuit 28.

[0017] The rotating plate 16 extends in a direction perpendicular to the rotation axis direction. Specifically, the rotating plate 16 is disk-shaped with a main surface extending in a direction perpendicular to the rotation axis direction, and is circular when viewed from the rotation axis direction. The rotating plate 16 is attached to one end of the rotating shaft 10 in the rotation axis direction. The axis of the rotating plate 16 and the rotation axis A are aligned. The rotating plate 16 rotates together with the rotating shaft 10.

[0018] The base plate 18 extends in a direction perpendicular to the rotation axis direction. Specifically, the base plate 18 is disk-shaped with a main surface perpendicular to the rotation axis direction, and is circular when viewed from the rotation axis direction. The base plate 18 is disposed at a distance from one end of the rotating shaft 10 and the rotating plate 16 in the rotation axis direction, and faces the rotating plate 16. The axis of the base plate 18 coincides with the rotation axis A. The base plate 18 is fixed to the inner surface of the case 12 and does not rotate.

[0019] The pair of magnets 20, 22 rotate together with the rotating shaft 10. Specifically, when the rotating shaft 10 rotates, the pair of magnets 20, 22 rotate together with the rotating shaft 10 and the rotating plate 16. The pair of magnets 20, 22 are arranged on a main surface of the rotating plate 16 facing away from the substrate 18. The pair of magnets 20, 22 are arranged at positions spaced apart in the direction of the rotation axis from the multiple power generating elements 24, 26. The pair of magnets 20, 22 overlap with the substrate 18 when viewed from the direction of the rotation axis.

[0020] The pair of magnets 20, 22 are arranged with a gap between them in a first orthogonal direction (the direction shown by arrow B in FIG. 2) that is perpendicular to the rotation axis A of the rotating shaft 10 and sandwiches the rotation axis A. In other words, the rotation axis A of the rotating shaft 10 is located between the pair of magnets 20, 22, and a space is formed between them.

[0021] The north and south poles of the pair of magnets 20, 22 are aligned in the first orthogonal direction so that the north pole is located on one side in the first orthogonal direction. In other words, each of the pair of magnets 20, 22 is magnetized in the first orthogonal direction.

[0022] The north and south poles of magnet 20 are aligned in a first orthogonal direction, with the north pole of magnet 20 positioned on one side of the first orthogonal direction relative to the south pole of magnet 20. The north pole of magnet 20 is disposed at a position closer to rotation axis A than the south pole of magnet 20 in the first orthogonal direction.

[0023] The north and south poles of magnet 22 are aligned in the first orthogonal direction, with the north pole of magnet 22 positioned on one side of the first orthogonal direction relative to the south pole of magnet 22. The north pole of magnet 22 is disposed at a position farther from rotation axis A than the south pole of magnet 22 in the first orthogonal direction.

[0024] As shown in Figure 3, the north and south poles of each of a pair of magnets 20, 22 are aligned in the first orthogonal direction so that the north pole is located on one side of the first orthogonal direction, thereby generating a magnetic field directed in one direction in the first orthogonal direction (see the arrow in Figure 3).

[0025] Each of the pair of magnets 20, 22 is arranged along the rotation direction of the rotary shaft 10. Each of the pair of magnets 20, 22 has an arc shape that is along the rotation direction of the rotary shaft 10.

[0026] The pair of magnets 20, 22 are arranged symmetrically with respect to the rotation axis A. The pair of magnets 20, 22 have the same shape and are arranged symmetrically in the first orthogonal direction.

[0027] One ends of a pair of magnets 20, 22 in a second orthogonal direction (the direction indicated by arrow C in Figure 2) that is perpendicular to the rotation axis A and perpendicular to the first orthogonal direction face each other with a gap in a direction parallel to the first orthogonal direction, and the other ends of the pair of magnets 20, 22 in the second orthogonal direction face each other with a gap in a direction parallel to the first orthogonal direction.

[0028] Each of the pair of magnets 20, 22 is plate-shaped with its thickness direction aligned with the rotation axis direction. Each of the pair of magnets 20, 22 has a main surface facing the multiple power generating elements 24, 26 in the rotation axis direction, and a main surface opposite the multiple power generating elements 24, 26 in the rotation axis direction. Here, "the main surface facing the power generating elements in the rotation axis direction of the magnet" refers to the main surface facing the rotation axis direction of the magnet, facing toward the power generating elements. Also, "the main surface opposite the power generating elements in the rotation axis direction of the magnet" refers to the main surface facing the rotation axis direction of the magnet, facing away from the power generating elements. The same applies hereinafter.

[0029] Each of the multiple power generating elements 24, 26 generates power due to changes in the magnetic field caused by the pair of magnets 20, 22 rotating together with the rotation shaft 10. Each of the multiple power generating elements 24, 26 is arranged on the main surface of the substrate 18 facing away from the rotating plate 16. When viewed from the direction of the rotation axis, the multiple power generating elements 24, 26 overlap with the substrate 18.

[0030] The power generating elements 24, 26 are disposed at positions offset from the rotation axis A. In other words, the power generating elements 24, 26 do not overlap with the rotation axis A when viewed from the rotation axis direction.

[0031] The multiple power generating elements 24, 26 are arranged with a phase difference in the rotation direction of the rotating shaft 10. In other words, the multiple power generating elements 24, 26 are arranged at different positions from each other in the rotation direction of the rotating shaft 10.

[0032] In the radial direction (the direction indicated by arrow Y in FIG. 2) about the rotation axis A, the distance from the rotation axis A to each of the multiple power generating elements 24, 26 is approximately equal to the distance from the rotation axis A to the outermost magnetic pole of each of the pair of magnets 20, 22. In other words, the distance from the rotation axis A to the power generating element 24 in the radial direction is approximately equal to the distance from the rotation axis A to the south pole of magnet 20, and approximately equal to the distance from the rotation axis A to the north pole of magnet 22. Furthermore, the distance from the rotation axis A to the power generating element 26 in the radial direction is approximately equal to the distance from the rotation axis A to the south pole of magnet 20, and approximately equal to the distance from the rotation axis A to the north pole of magnet 22.

[0033] The power generating element 24 extends in a tangential direction to the rotation direction of the rotating shaft 10 and is disposed on the main surface of the substrate 18 facing away from the rotating shaft 10 (away from the rotating plate 16). The power generating element 24 has a magnetic field sensing unit 30 and a coil 32 wound around the magnetic field sensing unit 30. The magnetic field sensing unit 30 is a magnetic material extending in a tangential direction to the rotation direction of the rotating shaft 10 and is located on the main surface of the substrate 18 facing away from the rotating plate 16. For example, the magnetic field sensing unit 30 is a magnetic material that exhibits the large Barkhausen effect and is a Wiegand wire that extends along a tangential line to the rotation direction of the rotating shaft 10. A Wiegand wire is a magnetic material whose magnetization direction is aligned in one longitudinal direction when a magnetic field of a predetermined value or greater is applied along the longitudinal direction of the Wiegand wire. When the direction of the magnetic flux flowing along the length of the Wiegand wire changes, the magnetization direction of the Wiegand wire suddenly reverses, inducing a voltage pulse across both ends of the coil wound around the Wiegand wire. In this way, the power generating element 24 generates electricity.

[0034] The power generating element 26 extends along a tangent to the rotation direction of the rotating shaft 10, and is disposed on the main surface of the substrate 18 facing away from the rotating shaft 10 (away from the rotating plate 16). The power generating element 26 has a magnetic field sensing part 34 and a coil 36 wound around the magnetic field sensing part 34. The magnetic field sensing part 34 is a magnetic material extending along a tangent to the rotation direction of the rotating shaft 10, and is located on the main surface of the substrate 18 facing away from the rotating plate 16. For example, the magnetic field sensing part 34 is a magnetic material that exhibits the large Barkhausen effect, and is a Wiegand wire extending in the tangent direction to the rotation direction of the rotating shaft 10. The power generating element 26 generates electricity in the same manner as the power generating element 24.

[0035] The control circuit 28 is disposed on the main surface of the substrate 18 facing the rotating shaft 10 (rotating plate 16), and is electrically connected to the power generating element 24 and the like. For example, the control circuit 28 determines the rotational position of the rotating shaft 10 based on which of the multiple power generating elements 24, 26 has generated power. Furthermore, for example, the rotation detector 14 may further include one or more magnetic sensors (not shown) that operate based on power from the multiple power generating elements 24, 26, and the control circuit 28 may determine the rotational position of the rotating shaft 10 based on which of the multiple power generating elements 24, 26 has generated power and the detection results of the one or more magnetic sensors.

[0036] 4 to 6 are diagrams showing the relationship between the rotational positions of the pair of magnets 20 and 22 and the distribution of magnetic flux density in the longitudinal direction of the power generating element 24. FIG.

[0037] As shown in (a) of Figure 4, when the first orthogonal direction and the longitudinal direction of the power generating element 24 are parallel, the magnetic sensing portion 30 of the power generating element 24 does not overlap with the pair of magnets 20, 22 when viewed from the direction of the rotation axis, and is located near one end of each of the pair of magnets 20, 22 in the second orthogonal direction.

[0038] At this time, as shown in (b) of Figure 4, the distribution of magnetic flux density in the longitudinal direction of the magnetic sensing part 30 does not have a peak at the center of the longitudinal direction of the magnetic sensing part 30, but is almost uniform near the center of the longitudinal direction of the magnetic sensing part 30.

[0039] As shown in (a) of Figure 5, when the second orthogonal direction and the longitudinal direction of the power generating element 24 are parallel, the magnetic sensing portion 30 of the power generating element 24 overlaps with the center of the N pole of the magnet 22 in the rotation direction of the rotating shaft 10 when viewed from the rotation axis direction.

[0040] At this time, as shown in FIG. 5(b), the distribution of magnetic flux density in the longitudinal direction of the magnetic sensing part 30 is smaller than in the state of FIG. 4(a), and is close to zero.

[0041] As shown in (a) of FIG. 6, the power generating element 24 generates a power generation pulse in a state between a state in which the first orthogonal direction is parallel to the longitudinal direction of the power generating element 24 and a state in which the second orthogonal direction is parallel to the longitudinal direction of the power generating element 24.

[0042] At this time, as shown in (b) of Figure 6, the distribution of magnetic flux density in the longitudinal direction of the magnetic sensing part 30 is such that the peak is not located at a position shifted from the longitudinal center of the magnetic sensing part 30, but is located near the longitudinal center of the magnetic sensing part 30.

[0043] As described above, by rotating the rotary shaft 10, the magnetic flux density in the longitudinal direction of the magnetic field sensing portion 30 of the power generating element 24 can be appropriately distributed, making it easier for the power generating element 24 to generate power appropriately.

[0044] The distribution of magnetic flux density in the longitudinal direction of the magnetic sensing portion 34 of the power generating element 26 will not be described in detail here, and reference will be made to the above-mentioned explanation of the distribution of magnetic flux density in the longitudinal direction of the magnetic sensing portion 30 of the power generating element 24, but the power generating element 26 will also be able to generate electricity appropriately, similar to the power generating element 24.

[0045] The rotation detector 14 according to the first embodiment has been described above.

[0046] The rotation detector 14 according to this embodiment includes a pair of magnets 20, 22 that rotate together with the rotating shaft 10, and a power generating element 24 that generates power by a change in the magnetic field caused by the pair of magnets 20, 22 rotating together with the rotating shaft 10. The pair of magnets 20, 22 are arranged on either side of the rotation axis A of the rotating shaft 10 and spaced apart in a first orthogonal direction that is orthogonal to the rotation axis A. The north and south poles of the pair of magnets 20, 22 are aligned in the first orthogonal direction so that the north pole is located on one side in the first orthogonal direction.

[0047] This makes it easier to appropriately distribute the magnetic flux density in the longitudinal direction of the power generating element 24, making it easier for the power generating element 24 to generate electricity appropriately.

[0048] In the rotation detector 14 according to this embodiment, each of the pair of magnets 20 and 22 is arranged along the direction of rotation of the rotating shaft 10.

[0049] This makes it easier to more appropriately distribute the magnetic flux density in the longitudinal direction of the power generating element 24, thereby making it easier to more appropriately generate power in the power generating element 24. In addition, the rotating shaft 10 can be easily provided between the pair of magnets 20, 22.

[0050] In the rotation detector 14 according to this embodiment, the pair of magnets 20 and 22 are arranged symmetrically with respect to the rotation axis A.

[0051] This makes it possible to prevent the magnetic flux density of the power generating element 24 from becoming biased in the longitudinal direction, making it easier for the power generating element 24 to generate electricity more appropriately.

[0052] In addition, in the rotation detector 14 according to this embodiment, the power generating element 24 is disposed at a position offset from the axis A of rotation.

[0053] This makes it easier to appropriately distribute the magnetic flux density in the longitudinal direction of the power generating element 24, even if the power generating element 24 cannot be arranged on the rotation axis A, making it easier for the power generating element 24 to appropriately generate power.

[0054] Moreover, the rotation detector 14 according to this embodiment includes a plurality of power generating elements 24 and 26.

[0055] This makes it easier for each of the multiple power generating elements 24, 26 to generate power appropriately, and also increases the number of times power is generated compared to when there is only one power generating element, so the rotational position of the rotating shaft 10 can be detected with higher accuracy.

[0056] (Second embodiment) Fig. 7 is a diagram showing a rotation detector according to the second embodiment. Note that the coil 32, the coil 36, etc. are not shown in Fig. 7. The same applies to Figs. 8 to 12.

[0057] As shown in FIG. 7, the rotation detector of the second embodiment differs from the rotation detector 14 mainly in that it includes a pair of magnets 20a and 22a (pair of magnets 20a, 22a) that is different from the pair of magnets 20, 22.

[0058] The pair of magnets 20a, 22a differs from the pair of magnets 20, 22 mainly in that each is a bar-shaped magnet extending in a direction perpendicular to the first orthogonal direction. The north and south poles of each of the pair of magnets 20a, 22a are aligned in the first orthogonal direction so that the north pole is located on one side in the first orthogonal direction.

[0059] This makes it possible to generate a magnetic field directed in one of the first orthogonal directions (see the arrow in FIG. 7(b)).

[0060] (Third embodiment) FIG. 8 is a diagram showing a rotation detector according to the third embodiment.

[0061] As shown in FIG. 8, the rotation detector of the third embodiment differs from the rotation detector 14 mainly in that it further includes a pair of magnetic bodies 38, 40 arranged between one ends of the pair of magnets 20, 22 in the second orthogonal direction and between the other ends of the pair of magnets 20, 22 in the second orthogonal direction.

[0062] The magnetic body 38 is disposed between one ends of the pair of magnets 20, 22 in the second orthogonal direction and connects these one ends together. The thickness of the magnetic body 38 in the rotation axis direction is equal to the thickness of the pair of magnets 20, 22.

[0063] The magnetic body 40 is disposed between the other ends of the pair of magnets 20, 22 in the second orthogonal direction and connects the other ends together. The thickness of the magnetic body 40 in the rotation axis direction is equal to the thickness of the pair of magnets 20, 22.

[0064] This makes it possible to generate a magnetic field directed in one of the first orthogonal directions (see the arrow in FIG. 8(b)), and to further increase the strength of the magnetic field.

[0065] The rotation detector of this embodiment further includes a pair of magnetic bodies 38, 40 respectively arranged between one end of the pair of magnets 20, 22 in a second orthogonal direction that is perpendicular to the rotation axis A and perpendicular to the first orthogonal direction, and between the other end of the pair of magnets 20, 22 in the second orthogonal direction.

[0066] This makes it easier to ensure the strength of the magnetic flux in the longitudinal direction of the power generating element 24. It also makes it easier to increase the permeance coefficient and to prevent the strength of the magnetic flux in the longitudinal direction of the power generating element 24 from weakening at high temperatures. Therefore, it becomes easier for the power generating element 24 to generate electricity appropriately.

[0067] (Fourth embodiment) FIG. 9 is a diagram showing a rotation detector according to the fourth embodiment.

[0068] As shown in FIG. 9, the rotation detector according to the fourth embodiment differs from the rotation detector 14 mainly in that it includes a pair of magnets 20b and 22b that are different from the pair of magnets 20 and 22.

[0069] The edge of each of the pair of magnets 20b, 22b on the rotation axis A side and the edge opposite the rotation axis A in the first orthogonal direction are curved like an elliptical arc when viewed from the rotation axis direction. That is, the edge 42 of magnet 20b on the rotation axis A side and the edge 44 opposite the rotation axis A in the first orthogonal direction are curved like an elliptical arc when viewed from the rotation axis direction. Also, the edge 46 of magnet 22b on the rotation axis A side and the edge 48 opposite the rotation axis A in the first orthogonal direction are curved like an elliptical arc when viewed from the rotation axis direction. Here, "the edge on the rotation axis A side" refers to the edge of the magnet that faces toward the rotation axis A. Also, "the edge opposite the rotation axis A" refers to the edge of the magnet that faces away from the rotation axis A. The same applies hereinafter.

[0070] In this embodiment, the edge of each of the pair of magnets 20b, 22b on the side of rotation axis A is curved like an arc of ellipse D centered on rotation axis A, and the edge of each of the pair of magnets 20b, 22b on the opposite side of rotation axis A is curved like an arc of ellipse E centered on rotation axis A.

[0071] For example, the ellipse associated with the edge of one magnet on the rotation axis A side of the pair of magnets 20b, 22b may be different from the ellipse associated with the edge of the other magnet on the rotation axis A side. Also, for example, the ellipse associated with the edge of one magnet on the opposite side of rotation axis A of the pair of magnets 20b, 22b may be different from the ellipse associated with the edge of the other magnet on the opposite side of rotation axis A of the pair of magnets 20b, 22b.

[0072] The edge of each of the pair of magnets 20b, 22b on the rotation axis A side and the edge on the opposite side to the rotation axis A are curved outward in the radial direction with the rotation axis A as the center.

[0073] The ellipticity of ellipse D associated with the edge of each of the pair of magnets 20b, 22b on the rotation axis A side is different from the ellipticity of ellipse E associated with the edge of the magnet on the opposite side of the rotation axis A. For example, ellipticity can be expressed as minor axis / major axis. In this embodiment, the ellipticity of ellipse D associated with the edge of each of the pair of magnets 20b, 22b on the rotation axis A side is smaller than the ellipticity of ellipse E associated with the edge of the magnet on the opposite side of the rotation axis A. In this embodiment, the major axis of ellipse D is smaller than the major axis of ellipse E, and the minor axis of ellipse D is smaller than the minor axis of ellipse E.

[0074] The major axis direction of ellipse D associated with the edge of each of the pair of magnets 20b, 22b on the rotation axis A side coincides with the major axis direction of ellipse E associated with the edge of the magnet on the opposite side of the rotation axis A. In this embodiment, the major axis direction of ellipse D associated with the edge of each of the pair of magnets 20b, 22b on the rotation axis A side and the major axis direction of ellipse E associated with the edge of the magnet on the opposite side of the rotation axis A each coincide with the second orthogonal direction.

[0075] This makes it possible to generate a magnetic field directed toward one side of the first orthogonal direction (see the arrow in FIG. 9(b)), and also makes it easier to adjust the magnetic flux density in the longitudinal direction of the power generating element 24.

[0076] In the rotation detector according to this embodiment, the edge of each of the pair of magnets 20b, 22b on the rotation axis A side and the edge on the opposite side to the rotation axis A are curved like an elliptical arc when viewed from the rotation axis direction. The ellipticity of ellipse D relating to the edge of each of the pair of magnets 20b, 22b on the rotation axis A side is different from the ellipticity of ellipse E relating to the edge of the magnet on the opposite side to the rotation axis A.

[0077] This makes it easier to adjust the magnetic flux density in the longitudinal direction of the power generating element 24, making it easier for the power generating element 24 to generate electricity appropriately.

[0078] (Fifth embodiment) FIG. 10 is a diagram illustrating a rotation detector according to the fifth embodiment.

[0079] As shown in FIG. 10, the rotation detector according to the fifth embodiment differs from the rotation detector 14 mainly in that it includes a pair of magnets 20c and 22c that are different from the pair of magnets 20 and 22.

[0080] Each of the pair of magnets 20c, 22c is inclined with respect to the first orthogonal direction so that the edge of the magnet opposite to the rotation axis A is positioned closer to the power generating element 24 than the edge of the magnet on the rotation axis A side.

[0081] That is, the magnet 20c is tilted with respect to the first orthogonal direction so that the edge 50 of the magnet 20c on the opposite side to the rotation axis A is located closer to the power generating element 24 than the edge 52 of the magnet 20c on the rotation axis A side.

[0082] The magnet 22c is tilted with respect to the first orthogonal direction so that an edge 54 of the magnet 22c on the opposite side to the rotation axis A is located closer to the power generating element 24 than an edge 56 of the magnet 22c on the rotation axis A side.

[0083] The principal surfaces of the pair of magnets 20c, 22c opposite the power generating element 24 in the direction of the rotation axis are inclined with respect to the first orthogonal direction so as to be positioned gradually closer to the power generating element 24 with increasing distance from the rotation axis A.

[0084] That is, the main surface 58 of the magnet 20c opposite the power generating element 24 in the direction of the rotation axis is inclined with respect to the first orthogonal direction so as to be positioned gradually closer to the power generating element 24 as it moves away from the rotation axis A.

[0085] Furthermore, a main surface 60 of the magnet 22c opposite the power generating element 24 in the direction of the rotation axis is inclined with respect to the first orthogonal direction so as to be positioned gradually closer to the power generating element 24 as it moves away from the rotation axis A.

[0086] This allows a magnetic field to be generated in one of the first orthogonal directions (see the arrow in FIG. 10(b)), and also makes it easier for the magnetic flux to reach the power generating element 24.

[0087] In the rotation detector according to this embodiment, the power generation element 24 and the pair of magnets 20c, 22c are arranged at different positions in the rotation axis direction. Each of the pair of magnets 20c, 22c is inclined with respect to the first orthogonal direction so that the end of the magnet on the opposite side to the rotation axis A is positioned closer to the power generation element 24 than the end of the magnet on the rotation axis A side. Note that here, "the end on the rotation axis A side" refers to the end of the magnet that faces toward the rotation axis A. Furthermore, "the end opposite to the rotation axis A" refers to the end of the magnet that faces away from the rotation axis A. The same applies hereinafter.

[0088] This allows the magnetic flux to reach the power generating element 24 more easily, making it easier for the power generating element 24 to generate electricity more appropriately.

[0089] In the rotation detector according to this embodiment, the power generating element 24 and the pair of magnets 20c, 22c are arranged at different positions in the rotation axis direction. The principal surfaces of the pair of magnets 20c, 22c, facing away from the power generating element 24 in the rotation axis direction, are inclined with respect to the first orthogonal direction so as to be positioned gradually closer to the power generating element 24 in the rotation axis direction as they move away from the rotation axis A.

[0090] This allows the magnetic flux to reach the power generating element 24 more easily, making it easier for the power generating element 24 to generate electricity more appropriately.

[0091] (Sixth embodiment) FIG. 11 is a diagram showing a rotation detector according to the sixth embodiment.

[0092] As shown in FIG. 11, the rotation detector according to the sixth embodiment differs from the rotation detector 14 mainly in that it includes a pair of magnets 20d and 22d that are different from the pair of magnets 20 and 22.

[0093] The pair of magnets 20d, 22d each have a semicircular arc shape that follows the rotation direction of the rotating shaft 10, and are integrally formed with each other to form a ring-shaped magnet. In other words, the rotation detector according to the sixth embodiment includes a ring-shaped magnet that follows the rotation direction of the rotating shaft 10.

[0094] For example, semicircular arc-shaped magnet 20d and semicircular arc-shaped magnet 22d may be formed separately, and then magnet 20d and magnet 22d may be joined together using a joining member or the like to form an integral unit. Alternatively, a ring-shaped member may be magnetized to form the ring-shaped magnet. In this case, one half of the ring-shaped magnet corresponds to magnet 20d, and the other half of the ring-shaped magnet corresponds to magnet 22d.

[0095] The north pole of magnet 20d is arranged next to and in succession with the south pole of magnet 22d in the direction of rotation of the rotating shaft 10, and the south pole of magnet 20d is arranged next to and in succession with the north pole of magnet 22d in the direction of rotation of the rotating shaft 10.

[0096] This makes it possible to generate a magnetic field directed in one of the first orthogonal directions (see the arrow in FIG. 11(b)).

[0097] In the rotation detector according to this embodiment, the pair of magnets 20d, 22d each have a semicircular arc shape that follows the rotation direction of the rotary shaft 10, and are integrally formed with each other to form an annular magnet.

[0098] This allows the positional relationship between the pair of magnets 20d and 22d to be easily fixed, making it easier for the power generating element 24 to generate power more appropriately.

[0099] (Seventh embodiment) FIG. 12 is a diagram showing a rotation detector according to the seventh embodiment.

[0100] As shown in FIG. 12, the rotation detector of the seventh embodiment differs from the rotation detector 14 mainly in that it includes a pair of magnets 20e, 22e that are different from the pair of magnets 20, 22, and in that it further includes a plurality of magnetic bodies 62, 64, 66.

[0101] The pair of magnets 20e, 22e each have a semicircular arc shape along the rotation direction, and are integrally formed with each other to form an annular magnet.

[0102] The north and south poles of one of the pair of magnets 20e, 22e are aligned in the rotational axis direction so that the north pole is located on one side in the rotational axis direction, and the north and south poles of the other of the pair of magnets 20e, 22e are aligned in the rotational axis direction so that the north pole is located on the other side in the rotational axis direction.

[0103] Specifically, the north and south poles of magnet 20e are aligned in the rotational axis direction so that the north pole is positioned in the opposite direction to power generation element 24. The north and south poles of magnet 22e are aligned in the rotational axis direction so that the north pole is positioned in the direction of power generation element 24 in the rotational axis direction.

[0104] The multiple magnetic bodies 62, 64 are respectively arranged on the edge portions of the pair of magnets 20e, 22e on the rotation axis A side. The magnetic body 62 is arranged on an edge portion 68 of the magnet 20e on the rotation axis A side, and is arranged along the rotation direction of the rotating shaft 10. The magnetic body 64 is arranged on an edge portion 70 of the magnet 22e on the rotation axis A side, and is arranged along the rotation direction of the rotating shaft 10. The magnetic bodies 62 and 64 are separated from each other.

[0105] The magnetic body 66 is arranged on the main surfaces of the pair of magnets 20e, 22e opposite the power generation element 24. Specifically, the magnetic body 66 is arranged on the main surface 72 of the magnet 20e opposite the power generation element 24 and on the main surface 74 of the magnet 22e opposite the power generation element 24. The magnetic body 66 is arranged along the rotation direction of the rotating shaft 10, and overlaps with the pair of magnets 20e, 22e when viewed from the rotation axis direction.

[0106] This makes it possible to generate a magnetic field directed in one direction of the rotation axis and a magnetic field directed in the other direction of the rotation axis (see the arrows in FIG. 12(b)).

[0107] In the rotation detector according to this embodiment, the north and south poles of one of the pair of magnets 20e, 22e are aligned in the rotation axis direction so that the north pole is located on one side in the rotation axis direction. The north and south poles of the other of the pair of magnets 20e, 22e are aligned in the rotation axis direction so that the north pole is located on the other side in the rotation axis direction. The rotation detector further includes a plurality of magnetic bodies 62, 64 respectively arranged on the edge portions of the pair of magnets 20e, 22e on the rotation axis A side in the first orthogonal direction.

[0108] This allows the magnetic field generated by the pair of magnets 20e, 22e to reach the power generating element 24 more easily, making it easier for the power generating element 24 to generate electricity more appropriately.

[0109] (Other embodiments, etc.) As described above, the embodiments have been described as examples of the technology disclosed in this application. However, the technology according to the present disclosure is not limited to these, and can be applied to embodiments or modified examples in which changes, substitutions, additions, omissions, etc. are made as appropriate without departing from the spirit of the present disclosure.

[0110] In the above-described embodiment, the edge of each of the pair of magnets 20b, 22b on the rotation axis A side is curved in the arc of ellipse D, and the edge of the magnet on the opposite side of the rotation axis A is curved in the arc of ellipse E. However, this is not limiting. FIG. 13A is a diagram showing another example of the magnet, and FIGS. 13B, 14A, and 14B are diagrams showing still other examples of the magnet. For example, the magnets may be formed as shown in FIGS. 13A, 13B, 14A, and 14B. Note that FIGS. 13A, 13B, 14A, and 14B show only one of the pair of magnets, and the other magnet is not shown. For example, the other magnet may be formed symmetrically to the one magnet.

[0111] Fig. 13A is a diagram showing another example of a magnet. For example, as shown in Fig. 13A, edge 102 on the rotation axis A side of magnet 100 may be curved like an arc of ellipse G centered at point F different from rotation axis A when viewed from the rotation axis direction, and edge 104 on the opposite side of rotation axis A of magnet 100 may be curved like an arc of ellipse H centered at point F when viewed from the rotation axis direction.

[0112] The ellipticity of the ellipse G associated with edge portion 102 is equal to the ellipticity of the ellipse H associated with edge portion 104. The long axis direction of the ellipse G associated with edge portion 102 is different from the long axis direction of the ellipse H associated with edge portion 104. Here, the long axis direction of the ellipse G associated with edge portion 102 is perpendicular to the long axis direction of the ellipse H associated with edge portion 104. Note that, for example, the long axis direction of the ellipse G associated with edge portion 102 does not have to be perpendicular to the long axis direction of the ellipse H associated with edge portion 104. For example, the long axis direction of the ellipse G associated with edge portion 102 is parallel to the second orthogonal direction, and the long axis direction of the ellipse H associated with edge portion 104 coincides with the first orthogonal direction. The ellipse G is the same size as the ellipse H.

[0113] Fig. 13B is a diagram showing another example of a magnet. For example, as shown in Fig. 13B, edge 108 on the rotation axis A side of magnet 106 may be curved like an arc of ellipse J centered at point I different from rotation axis A when viewed from the rotation axis direction, and edge 110 on the opposite side of magnet 106 from rotation axis A may be curved like an arc of ellipse K centered at point I when viewed from the rotation axis direction.

[0114] The ellipticity of the ellipse J associated with edge portion 108 is different from the ellipticity of the ellipse K associated with edge portion 110. The major axis direction of the ellipse J associated with edge portion 108 is different from the major axis direction of the ellipse K associated with edge portion 110. Specifically, the major axis direction of the ellipse J associated with edge portion 108 is perpendicular to the major axis direction of the ellipse K associated with edge portion 110. Note that, for example, the major axis direction of the ellipse J associated with edge portion 108 does not have to be perpendicular to the major axis direction of the ellipse K associated with edge portion 110. For example, the major axis direction of the ellipse J associated with edge portion 108 coincides with the first orthogonal direction, and the major axis direction of the ellipse K associated with edge portion 110 is parallel to the second orthogonal direction. The major axis of the ellipse J associated with edge portion 108 is smaller than the minor axis of the ellipse K associated with edge portion 110.

[0115] Fig. 14A is a diagram showing yet another example of a magnet. For example, as shown in Fig. 14A, edge 114 of magnet 112 on the rotation axis A side may be curved like an arc of ellipse M centered at point L different from rotation axis A when viewed from the rotation axis direction, and edge 116 of magnet 112 on the opposite side from rotation axis A may be curved like an arc of ellipse N centered at point L when viewed from the rotation axis direction.

[0116] The ellipticity of the ellipse M associated with the edge portion 114 is different from the ellipticity of the ellipse N associated with the edge portion 116. The major axis direction of the ellipse M associated with the edge portion 114 coincides with the major axis direction of the ellipse N associated with the edge portion 116. For example, the major axis direction of the ellipse M associated with the edge portion 114 and the major axis direction of the ellipse N associated with the edge portion 116 coincide with the first orthogonal direction. The major axis of the ellipse M associated with the edge portion 114 is smaller than the major axis of the ellipse N associated with the edge portion 116 and larger than the minor axis of the ellipse N. The minor axis of the ellipse M associated with the edge portion 114 is smaller than the minor axis of the ellipse N associated with the edge portion 116.

[0117] 14B is a diagram showing yet another example of a magnet. For example, as shown in FIG. 14B, edge 120 of magnet 118 on the rotation axis A side may be curved like an arc of ellipse P centered at point O different from rotation axis A when viewed from the rotation axis direction, and edge 122 of magnet 118 on the opposite side from rotation axis A may be curved like an arc of ellipse Q centered at point O when viewed from the rotation axis direction.

[0118] The ellipticity of the ellipse P associated with the edge portion 120 is different from the ellipticity of the ellipse Q associated with the edge portion 122. The major axis direction of the ellipse P associated with the edge portion 120 coincides with the major axis direction of the ellipse Q associated with the edge portion 122. For example, the major axis direction of the ellipse P associated with the edge portion 120 and the major axis direction of the ellipse Q associated with the edge portion 122 are both parallel to the second orthogonal direction. The major axis of the ellipse P associated with the edge portion 120 is smaller than the major axis of the ellipse Q associated with the edge portion 122 and larger than the minor axis of the ellipse Q. The minor axis of the ellipse P associated with the edge portion 120 is smaller than the minor axis of the ellipse Q associated with the edge portion 122.

[0119] In the above-described embodiment, the rotation detector 14 is described as including a plurality of power generating elements 24, 26. However, the present invention is not limited to this. For example, the rotation detector may include only one power generating element.

[0120] In the above-described embodiment, the case where the multiple power generating elements 24, 26 are arranged on the main surface of the substrate 18 facing away from the rotating plate 16 has been described, but the present invention is not limited to this. For example, the multiple power generating elements may be arranged on the main surface of the substrate facing the rotating plate.

[0121] In the above-described embodiment, the pair of magnets 20, 22 are arranged on the main surface of the rotating plate 16 facing away from the substrate 18, but this is not limiting. For example, the pair of magnets may be arranged on the main surface of the rotating plate facing the substrate. [Industrial Applicability]

[0122] The rotation detector according to the present disclosure can be used to detect the rotation of the rotating shaft of a motor that rotates a load. [Explanation of symbols]

[0123] 14 Rotation detector 16 Rotating Plate 18 PCB 20, 20a, 20b, 20c, 20d, 20e, 22, 22a, 22b, 22c, 22d, 22e, 100, 106, 112, 118 Magnets 24,26 Power generating element 28 Control circuit 30,34 Magnetically sensitive part 32,36 Coil 38,40,62,64,66 Magnetic material 42,44,46,48,50,52,54,56,68,70,102,104,108,110,114,116,120,122 Edge 58, 60, 72, 74 Main surfaces

Claims

1. A pair of magnets that rotate together with the rotation shaft; a power generation element that generates power by a change in a magnetic field caused by the pair of magnets rotating together with the rotation shaft, The pair of magnets are arranged on either side of a rotation axis of the rotation shaft and spaced apart in a first orthogonal direction orthogonal to the rotation axis, Satisfy either (1) or (2) below: (1) The north pole and south pole of each of the pair of magnets are aligned in the first orthogonal direction so that the north pole is located on one side in the first orthogonal direction. (2) The north and south poles of one of the pair of magnets are aligned in the direction of the rotation axis so that the north pole is located on one side in the direction of the rotation axis, and the north and south poles of the other of the pair of magnets are aligned in the direction of the rotation axis so that the north pole is located on the other side in the direction of the rotation axis. In the rotation detector, the power generating element is disposed at a position offset from the rotation axis, The pair of magnets are arranged such that ends of the pair of magnets in a second orthogonal direction perpendicular to the first orthogonal direction are spaced apart from each other, When the magnetic sensing portion of the power generating element is viewed from the direction of the rotation axis, and the longitudinal direction of the power generating element is substantially parallel to the first orthogonal direction, at least a portion of the magnetic sensing portion does not overlap with the pair of magnets, and at least another portion of the magnetic sensing portion is located near each end of the pair of magnets in the second orthogonal direction. Rotation detector.

2. Each of the pair of magnets is arranged along the rotation direction of the rotation shaft. The rotation detector according to claim 1 .

3. The pair of magnets are arranged symmetrically with respect to the rotation axis. The rotation detector according to claim 1 .

4. an edge portion of each of the pair of magnets on the rotation axis side and an edge portion on the opposite side to the rotation axis are curved in an elliptical arc shape when viewed from the rotation axis direction, At least one of the following (3) and (4) is satisfied: (3) The ellipticity of the ellipse of each of the pair of magnets on the rotation axis side is different from the ellipticity of the ellipse of each of the pair of magnets on the opposite side from the rotation axis. (4) The direction of the major axis of the ellipse associated with the edge of each of the pair of magnets on the rotation axis side is different from the direction of the major axis of the ellipse associated with the edge of the magnet on the opposite side from the rotation axis. The rotation detector according to claim 1 .

5. The condition (4) is satisfied, and the major axis direction of the ellipse relating to the edge portion of each of the pair of magnets on the rotation axis side is perpendicular to the major axis direction of the ellipse relating to the edge portion of the magnet on the opposite side to the rotation axis.

5. The rotation detector according to claim 4.

6. a pair of magnetic bodies respectively disposed between one end of the pair of magnets in a second orthogonal direction orthogonal to the rotation axis and the first orthogonal direction, and between the other end of the pair of magnets in the second orthogonal direction; The rotation detector according to claim 1 .

7. the power generation element and the pair of magnets are disposed at different positions in the direction of the rotation axis, each of the pair of magnets is inclined with respect to the first orthogonal direction so that an edge of the magnet on the opposite side to the rotation axis is positioned closer to the power generating element in the rotation axis direction than an edge of the magnet on the rotation axis side; The rotation detector according to claim 1 .

8. the power generation element and the pair of magnets are disposed at different positions in the direction of the rotation axis, a main surface of each of the pair of magnets on the opposite side to the power generation element in the rotation axis direction is inclined with respect to the first orthogonal direction so as to be gradually positioned closer to the power generation element in the rotation axis direction as the main surface becomes more distant from the rotation axis; The rotation detector according to claim 1 .

9. each of the pair of magnets has a semicircular arc shape that extends along the rotation direction of the rotation shaft; 2. The rotation detector according to claim 1, wherein at least a portion of the magnetic sensing portion of the power generating element overlaps with a central portion of one of the pair of magnets when viewed from the direction of the rotation axis, when the longitudinal direction of the power generating element and the second orthogonal direction are parallel.

10. The pair of magnets each have a semicircular arc shape that follows the rotation direction of the rotation shaft, The magnetic bearing further includes a plurality of magnetic bodies that satisfy the condition (2) and are arranged on the edge portion of each of the pair of magnets on the rotation axis side in the first orthogonal direction. The rotation detector according to claim 1 .

11. A plurality of the power generating elements are provided. A rotation detector according to any one of claims 1 to 9.

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