Rotation detection device

Abstract

The rotation detection device includes an annular multi-pole magnet provided on a rotating shaft and a power generation sensor that detects a magnetic field that changes with rotation of the multi-pole magnet. The power generation sensor includes a magnetic conductive wire exhibiting a large Barkhausen effect, a coil wound around the magnetic conductive wire, and a pair of magnetic flux conduction sheets comprising soft magnetic members magnetically coupled to both ends of the magnetic conductive wire, respectively. The annular multi-pole magnet has a magnetization pattern inclined with respect to the rotation axis at the outer peripheral portion. The power generation sensor faces the magnetization pattern of the multipole magnet in a posture in which the axial direction of the magnetic wire is parallel to the rotation axis.

Description

[0001] Related applications

[0002] This application claims priority to Japanese Patent Application No. 2023-67639, filed on April 18, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a rotation detection device using a power generation sensor. Background Technology

[0004] Magnetic wires exhibiting the large Backhausen effect (large Backhausen jump) are called Wiegand wires or pulse wires. These magnetic wires consist of a core and a skin portion surrounding the core. One of the core and the skin portion is a soft magnetic layer that reverses its magnetization direction even under a weak magnetic field, while the other is a hard magnetic layer whose magnetization direction does not reverse without a strong magnetic field. By winding a coil around such a magnetic wire, a power generation sensor can be constructed.

[0005] When the hard magnetic layer and the soft magnetic layer are magnetized in the same direction along the axis of the conductor, if the strength of an external magnetic field in the opposite direction to their magnetization direction increases and reaches a certain strength, the magnetization direction of the soft magnetic layer reverses. This reversal of magnetization direction propagates from a portion of the magnetic conductor as a starting point to the entire conductor, and the magnetization direction of the soft magnetic layer reverses simultaneously. At this time, the Big Barkhausen effect is exhibited, inducing a pulse signal in the coil wound on the magnetic conductor. When the strength of the external magnetic field increases further and reaches a certain strength, the magnetization direction of the hard magnetic layer reverses.

[0006] In this specification, the magnetic field strength when the magnetization direction of the soft magnetic layer is reversed is referred to as the "operating magnetic field," and the magnetic field strength when the magnetization direction of the hard magnetic layer is reversed is referred to as the "stable magnetic field."

[0007] Regardless of the rate of change of the input magnetic field (external magnetic field), the output voltage obtained from the coil remains constant and exhibits hysteresis characteristics with respect to the input magnetic field, thus possessing features such as no jitter. Therefore, the pulse signal generated from the coil is used in position detection devices, etc. Since the output from the coil contains electricity, it can be configured as a power-generating sensor (power-generating sensor) that does not require an external power supply. In other words, without providing external power, the peripheral circuitry can also be activated by the energy output from the coil.

[0008] To demonstrate the large Backhausen effect, it is necessary to start with the hard and soft magnetic layers having the same magnetization direction, and then reverse the magnetization direction of only the soft magnetic layer. When the hard and soft magnetic layers have different magnetization directions, even reversing the magnetization direction of only the soft magnetic layer will not generate a pulse signal, or if it does, the pulse signal will be extremely small.

[0009] Furthermore, to maximize the obtained power, it is crucial that the magnetization reversal of the soft magnetic layer is achieved throughout the entire magnetic conductor, starting from a state where the magnetization direction is consistent across the entire conductor. When the magnetization direction of the magnetic conductor is inconsistent across parts, only very small pulse signals can be obtained. Therefore, it is preferable to apply a uniform magnetic field throughout the entire magnetic conductor.

[0010] When an alternating magnetic field is applied to the power generation sensor, two pulse signals are generated for one cycle: a positive pulse signal and a negative pulse signal. A magnet can be used as the source of the magnetic field. The alternating magnetic field is applied to the power generation sensor by the rotation of the magnet, and the rotation position is detected by counting the generated pulse signals.

[0011] Patent Documents 1 and 2 describe examples of devices for detecting changes in the magnetic field accompanying the rotation of a magnet in a magnetic wire exhibiting a large Backhausen jump.

[0012] Patent Document 1 discloses a rotational speed detection device comprising a sensor consisting of a tone wheel magnetized into multiple poles and a magnetic wire exhibiting a large Backhausen transition. In the structure shown in Figure 1 of Patent Document 1, the magnetic wire is arranged on the outer periphery of the tone wheel, with its length direction as the radial direction of the tone wheel's rotation axis. One end of the magnetic wire is positioned close to the outer peripheral surface of the tone wheel, and the other end of the magnetic wire is attached to one end of a pole piece of a strongly magnetic material. Furthermore, the other end of the pole piece is positioned close to the outer peripheral surface of the tone wheel. With this structure, the magnetic field from the tone wheel can be guided by the pole piece, allowing adjustment of the specified magnetic field strength required to exhibit a large Backhausen transition.

[0013] Figure 2 of Patent Document 1 illustrates a structure in which a magnetic conductor is positioned on the outer periphery of the tone wheel, with its length parallel to the tangent direction of the circumference relative to the axis of rotation. At both ends of the magnetic conductor are pole pieces of strongly magnetic material, which guide the magnetic field from the tone wheel. This allows adjustment of the specified magnetic field strength required to produce the Grand Backhausen transition.

[0014] In the structure shown in Figures 3 to 10 of Patent Document 1, the magnetic wire is positioned with its length parallel to the rotation axis of the tone wheel and is disposed on the outer periphery of the tone wheel. The magnetic wire does not include pole pieces. Regarding the arrangement of this magnetic wire, in Figures 3 and 10 of Patent Document 1... Figure 5 , Figure 8In various configurations of the tone wheel shown in Figure 10, a magnetic field of a specified strength is applied to express the large Backhausen transition.

[0015] In the pole pieces shown in Figures 1 and 2 of Patent Document 1, the assembly of the device is complex because it must have a shape corresponding to the magnetization spacing, and the device performance depends on the assembly precision. Furthermore, in the structure of Figure 1 of this document, the magnetic field strength is uneven at one end of the magnetic conductor directly facing the tone wheel and at the other end through the pole piece that induces the magnetic field. In the structure of Figure 2 of this document, the area of ​​the pole piece facing the tone wheel is relatively small. Therefore, none of these structures are sufficiently effective as units for applying a uniform operating magnetic field and a stable magnetic field to the entire magnetic conductor.

[0016] Without the electrode of Patent Document 1, as shown in Figures 4, 7, and 9 of that document, the magnetic flux lines leaking from the magnet are not parallel to the length direction of the magnetic conductor. Therefore, to make the magnetic flux lines parallel to the length direction of the magnetic conductor, Figure 3 of that document is required. Figure 5 , Figure 8 As shown in Figure 10, compared to the structures in Figures 11 and 12 of this document, even with the same number of poles arranged circumferentially (i.e., the same detection resolution), the number of magnetic poles arranged on the outer periphery of the tone wheel must be 2 or 4 times. Therefore, there is a problem that the magnetic pole pattern must be made more complex.

[0017] Such magnetic pole patterns can be achieved by attaching magnetized magnets to a cylindrical yoke, but attaching magnets requires time. Typically, multi-pole magnetization of a cylindrical annular magnet can reduce time compared to attaching magnets, but achieving such complex magnetic pole patterns through magnetization is very difficult. Even if magnetization is not possible, or if it is already done, the yoke used for magnetization becomes complex and expensive.

[0018] Furthermore, without increasing the width of the magnetization gap (the circumferential width of the magnetic poles), it is impossible to apply a stable magnetic field of sufficient strength to the magnetic wire. Therefore, this results in an increase in the size of the device.

[0019] Patent Document 2 discloses a rotation detection device comprising a magnetic sensor with a coil wound on a magnetic wire exhibiting a large Backhausen transition. The magnetic sensor is positioned on the outer periphery of the track of the magnetic field forming section, such that the length direction of the magnetic wire is parallel to the axial direction of the rotation axis. The magnetic field forming section has two permanent magnets with four poles arranged circumferentially. These two permanent magnets are arranged on the rotation axis with different poles along the axial direction of the rotation axis. This structure allows for miniaturization of the device.

[0020] The structure of Patent Document 2 is the same as that of Patent Document 1. Figure 6The structure is similar, with two magnetic field forming parts (permanent magnets) arranged axially separate along the rotation axis, and an unmagnetized portion (the portion without magnetic poles) provided. However, since two components (permanent magnets) need to be installed, the assembly of the device is cumbersome. Furthermore, since the phase alignment of the magnetic poles of the two magnets affects performance, the device performance depends on assembly accuracy. Moreover, since it is a structure without a flux-conducting sheet (flux-induction sheet), similar to Patent Document 1, a stable magnetic field of sufficient strength cannot be applied to the magnetic conductor unless the width of the magnetization gap (circumferential width of the magnetic poles) is increased. Therefore, there is a problem of the device becoming larger.

[0021] Existing technical documents

[0022] Patent documents

[0023] Patent Document 1: Japanese Patent Application Publication No. 8-136558

[0024] Patent Document 2: Japanese Patent Application Publication No. 2022-55001 Summary of the Invention

[0025] The technical problem that the invention aims to solve

[0026] Thus, in the case of a multipole rotating body where the magnetic field source is a magnetic conductor, if the magnetic conductor is parallel to the axis of rotation and a magnetic field parallel to the axis of rotation is applied to the entire magnetic conductor with uniform intensity, the structure becomes complex and difficult to miniaturize. In addition, if the magnetic conductor is arranged such that its axis (length direction) is set as the circumferential tangent or radial direction of the axis of rotation, the shape and arrangement of the magnetic components need to be designed according to the magnetization spacing, which also results in a lack of versatility.

[0027] Therefore, one embodiment of the present invention provides a rotation detection device with a simple and small structure, which can detect rotation by a combination of a multipole magnet and a power generation sensor.

[0028] Technical solutions to solve technical problems

[0029] One embodiment of the present invention provides a rotation detection device that, by combining a power generation sensor having a magnetic flux conduction sheet (magnetic flux induction sheet) with a ring-shaped multipole magnet having an inclined magnetization pattern on its outer periphery, can obtain a simple, small and high-output signal.

[0030] One embodiment of the present invention provides a rotation detection device having the features described below.

[0031] 1. A rotation detection device comprising an annular multipole magnet disposed on a rotation axis and a power generation sensor (e.g., a power generation sensor) for detecting a magnetic field that changes as the multipole magnet rotates.

[0032] The power generation sensor includes:

[0033] A magnetic wire that exhibits the large Backhausen effect;

[0034] A coil wound around the magnetic wire; and

[0035] A pair of flux-conducting plates, each composed of soft magnetic material components magnetically coupled to both ends of the magnetic conductor, are symmetrical about each other with respect to a plane of symmetry positioned at the axial center of the magnetic conductor.

[0036] The ring-shaped multipole magnet has a magnetization pattern tilted relative to the rotation axis on its outer periphery.

[0037] The power generation sensor is positioned opposite the magnetization pattern of the multipole magnet with the axis (length direction) of the magnetic conductor parallel to the axis of rotation.

[0038] According to this structure, a power generation sensor is configured such that the axis of the magnetic wire is parallel to the rotation axis of the toroidal multipole magnet. Furthermore, the tilted magnetization pattern of the multipole magnet allows different magnetic poles to be aligned with a pair of flux-conducting plates magnetically coupled to both ends of the magnetic wire. Consequently, as the multipole magnet rotates together with the rotation axis, the magnetic wire exhibits the large Backhausen effect, generating a pulsed voltage.

[0039] Furthermore, for toroidal multipole magnets with tilted magnetization patterns on their outer periphery, simple and inexpensive magnets, such as those used in electric motors, can typically be used. The combination of such a multipole magnet with a power-generating sensor having a magnetic flux-conducting plate is relatively easy, forming a versatile rotation detection device.

[0040] Thus, by combining a ring-shaped multipole magnet with an inclined magnetization pattern and a power generation sensor with a magnetic flux conduction plate, a rotation detection device that can detect rotation with a simple and small structure can be realized.

[0041] 2. The rotation detection device as described in item 1, wherein the pair of magnetic flux conductive plates comprises:

[0042] A pair of orthogonal axial portions, each fixing one end of the magnetic conductor, extending parallel to each other from the ends of the magnetic conductor in an axially orthogonal direction to the axial direction; and

[0043] A pair of parallel axial portions, extending from the front ends of the pair of orthogonal axial portions in a direction toward each other along the axial direction, with their approaching ends spaced apart from each other in the axial direction and facing each other.

[0044] The pair of axially parallel portions are opposite to the magnetization pattern of the multipole magnet.

[0045] According to this structure, the axially parallel portion, parallel to the axis of the magnetic conductor, is located between the magnetic pole face of the inclined magnetization pattern formed on the outer periphery of the toroidal multipole magnet and the magnetic conductor. Thus, the applied magnetic field is collected by the flux-conducting sheet, which is composed of soft magnetic material components, and guided to both ends of the magnetic conductor. Furthermore, the magnetic flux in the direction intersecting the axis of the magnetic conductor is shielded by the axially parallel portion. In this way, since a magnetic field along the axis can be applied to the magnetic conductor, even a small magnetization gap can sufficiently induce the large Backhausen effect. In other words, a rotation detection device capable of obtaining a small size and a high output signal can be realized.

[0046] 3. The rotation detection device as described in item 2, wherein the distance between the two axially aligned portions at the coupling position with the magnetic conductor is 5% to 50% of the distance between the two axially aligned portions at the coupling position with the magnetic conductor.

[0047] This structure allows for the almost complete extraction of the large Backhausen effect, a characteristic of magnetic conductors, thus enabling the realization of small and high-output power generation sensors.

[0048] 4. The rotation detection device as described in any one of claims 1 to 3, wherein the magnetization pattern comprises a plurality of magnetic poles arranged circumferentially around the rotation axis and formed as a strip inclined relative to the rotation axis, the plurality of magnetic poles comprising N poles and S poles arranged alternately along the circumferential direction.

[0049] This structure enables a pair of magnetic flux conduction plates in the power generation sensor to conduct magnetic flux from magnetic poles of different polarities, thus enabling a small and high-output power generation sensor.

[0050] 5. The rotation detection device as described in item 4, wherein when one end of the magnetic conductor of the power generation sensor is opposite to one of the N poles (typically opposite in the direction of the rotation radius of the rotation axis via a magnetic flux conduction sheet), the tilt angle (pole angle) of the plurality of magnetic poles relative to the rotation axis is determined such that the other end of the magnetic conductor is opposite to one of the adjacent S poles of the N pole (typically opposite in the direction of the rotation radius of the rotation axis via a magnetic flux conduction sheet).

[0051] This structure enables the two ends of a magnetic wire to efficiently conduct magnetic flux from magnetic poles of different polarities, thus enabling the realization of a small and high-output power generation sensor.

[0052] 6. The rotation detection device as described in item 4, when one of the pair of magnetic flux conductive plates of the power generation sensor is opposite to one of the N poles (typically opposite in the direction of the rotation radius of the rotation axis), determines the tilt angle (pole angle) of the plurality of magnetic poles relative to the rotation axis such that the other of the pair of magnetic flux conductive plates is opposite to one of the adjacent S poles of the N pole (typically opposite in the direction of the rotation radius of the rotation axis).

[0053] This structure enables a pair of magnetic flux conduction plates in the power generation sensor to effectively conduct magnetic flux from magnetic poles of different polarities, thus enabling a small and high-output power generation sensor.

[0054] 7. The rotation detection device as described in any one of claims 1 to 6 further comprises a magnetic sensor that identifies the magnetic poles of the annular multipole magnet at a predetermined position in the circumference around the rotation axis.

[0055] According to this structure, by using a magnetic sensor at a predetermined position in the circumference to identify the magnetic poles, the state of the magnetic field applied to the power generation sensor can be determined. Therefore, by using the output signal of the magnetic sensor, the forward and reverse rotation of the rotating shaft can be identified, that is, the direction of rotation can be detected.

[0056] 8. The rotation detection device as described in any one of claims 1 to 7, further comprising a substrate disposed between the power generation sensor and the multipole magnet.

[0057] The power generation sensor is mounted on the main surface of the substrate on the side opposite to the multipole magnet.

[0058] The magnetic sensor can also be mounted on the substrate together with the power generation sensor. This allows for accurate determination of the relative configuration of the power generation sensor and the magnetic sensor.

[0059] The above and other objects, features and effects of the present invention will become more apparent from the description of the embodiments with reference to the accompanying drawings and as described below. Attached Figure Description

[0060] Figure 1A This is a perspective view of the rotation detection device according to the first embodiment.

[0061] Figure 1B It is along Figure 1A The main view is obtained by observing the direction of arrow 11.

[0062] Figure 2A This is a three-dimensional view obtained by magnifying the power generation sensor included in the rotation detection device.

[0063] Figure 2B It is along Figure 2AThe main view is obtained by observing in the direction of arrow 101.

[0064] Figure 3A , Figure 3B and Figure 3C This is a graph showing the results of a two-dimensional magnetic simulation of a structure (comparative example) excluding the flux-conducting sheet.

[0065] Figure 4A , Figure 4B and Figure 4C This is a diagram showing the results of a two-dimensional magnetic simulation of a structure including a magnetic flux conduction sheet (example).

[0066] Figure 5 It is an image obtained by observing the magnetization pattern of the oblique pole magnet used in the experiment using a magnetic display.

[0067] Figure 6 This is a graph showing the experimental results obtained by studying the relationship between the ratio of the distance between the proximal ends to the distance between the orthogonal parts of a pair of magnetic flux conduction plates and the output wave height.

[0068] Figure 7A This is a perspective view of the rotation detection device involved in the comparative example. Figure 7B yes Figure 7A A top view of the structure.

[0069] Figure 8 This is a perspective view of the rotation detection device according to the second embodiment. Detailed Implementation

[0070] The present invention will now be described based on the illustrated embodiments. However, the present invention is not limited to the embodiments described below.

[0071] [First Implementation Method]

[0072] Figure 1A and Figure 1B A rotation detection device 10 based on the first embodiment is shown. Figure 1A This is a perspective view of the rotation detection device 10. Figure 1B It is along Figure 1A The main view is obtained by observing the direction of arrow 11.

[0073] The rotation detection device 10 includes an annular multipole magnet 200 disposed on a rotation shaft 300 and a power generation sensor 100. The rotation shaft 300 rotates about a rotation axis 300a that is aligned with its central axis, and the multipole magnet 200 also rotates together with the rotation shaft 300 about the rotation axis 300a.

[0074] The power generation sensor 100 includes a magnetic wire 110 exhibiting the large Backhausen effect and a coil 120 wound on the magnetic wire 110. The power generation sensor 100 also includes a pair of flux-conducting sheets 130, 131 (flux-inductive sheets), which are composed of a pair of soft magnetic body components magnetically coupled to the two ends of the magnetic wire 110, respectively.

[0075] The toroidal multipole magnet 200 has a magnetization pattern on its outer periphery that is inclined relative to the rotation axis 300. The toroidal shape is a rotating body with the rotation axis 300a as its central axis, and in this embodiment, it is cylindrical. The magnetization pattern on the outer periphery is inclined relative to a direction parallel to the rotation axis 300a.

[0076] The power generation sensor 100 arranges the axial direction (line length direction) of the magnetic wire 110 parallel to the rotation axis 300a, so that a pair of magnetic flux conduction plates 130, 131 are opposite to the magnetization pattern.

[0077] Figure 2A This is a 3D view of the power generation sensor 100. Figure 2B It is along Figure 2A The front view is obtained by observing the direction of arrow 101. The power generation sensor 100 includes a magnetic wire 110 exhibiting the large Backhausen effect, a coil 120 wound around the magnetic wire 110, and a pair of flux-conducting sheets 130, 131 made of soft magnetic material components. The coil 120 is wound around the magnetic wire 110 such that the first end 111 and the second end 112 of the magnetic wire 110 are exposed at the same length. In this embodiment, the coil 120 is wound around the magnetic wire 110 between the pair of flux-conducting sheets 130, 131. The pair of flux-conducting sheets 130, 131 are magnetically coupled to the first end 111 and the second end 112 of the magnetic wire 110, respectively.

[0078] A pair of flux-conducting plates 130 and 131 have substantially the same shape and size. More specifically, the pair of flux-conducting plates 130 and 131 are symmetrically configured with respect to a plane of symmetry 115 (a virtual plane used to illustrate the geometric configuration) orthogonal to the axial x-axis at the center position (hereinafter referred to as the "axial center position") 113 of the magnetic conductor 110 (the direction of line length). The pair of flux-conducting plates 130 and 131 include: an axially orthogonal portion 133 extending parallel to each other from both ends 111 and 112 of the magnetic conductor 110 along an axially orthogonal direction z orthogonal to the axial x-axis, and an axially parallel portion 134 extending from the front end of the axially orthogonal portion 133 in a direction approaching each other along the axial x-axis. More specifically, the flux-conducting plates 130 and 131 have an orthogonal portion 133 of approximately cuboid shape and an axially parallel portion 134 of approximately cuboid shape connected to their front ends, and the junction of the orthogonal portion 133 and the axially parallel portion 134 has an L-shaped right-angle bend.

[0079] In this example, the orthogonal shaft portion 133 has a thickness W in the axial x direction. At the coupling position with the magnetic wire 110, the opposing inner surfaces of a pair of orthogonal shaft portions 133 are spaced apart by a distance D in the axial x direction. In a pair of parallel shaft portions 134, their proximal ends 134a are spaced apart by a distance L in the axial x direction.

[0080] The two ends 111 and 112 of the magnetic wire 110 are respectively fixed to the base end of the axially orthogonal portion 133 of a pair of magnetic flux conducting plates 130 and 131. More specifically, wire arrangement portions 130a and 131a are provided at the base end of the axially orthogonal portion 133, and the wire arrangement portions 130a and 131a are formed with holes or grooves extending along the axial x. Figure 2A Examples of wire arrangement portions 130a and 131a formed by holes are shown. When the wire arrangement portions 130a and 131a are formed by grooves, it is preferable that the grooves deepen in the axial orthogonal direction z, opening towards the end face opposite to the axis-parallel portion 134. The first end 111 and the second end 112 of the magnetic wire 110 are fixed to the axis-orthogonal portion 133 in the wire arrangement portions 130a and 131a, passing through the axis-orthogonal portion 133. More specifically, by distributing resin (not shown) in the holes or grooves constituting the wire arrangement portions 130a and 131a, the ends 111 and 112 of the magnetic wire 110 are fixed to the axis-orthogonal portion 133 and coupled to each other. Thus, the magnetic wire 110 and the pair of magnetic flux conductive sheets 130 and 131 are mechanically coupled to each other and magnetically coupled to each other.

[0081] The proximal ends 134a of the axially parallel portions 134 of a pair of flux-conducting plates 130 and 131 are positioned opposite each other, sandwiching a plane of symmetry 115 passing through the axial center position 113 of the magnetic wire 110. That is, their proximal ends 134a are spaced apart and face each other along the axial x-axis. The midpoint of this interval along the axial x-axis corresponds to the position of the axial center position 113 along the axial x-axis.

[0082] Therefore, the distances from the approach ends 134a of the pair of parallel axial portions 134 to the plane of symmetry 115 in the axial x direction are equal. This interval in the axial x direction, L, is set to 5% to 50% of the distance D between the pair of orthogonal axial portions 133 at the coupling position of the magnetic wire 110 and the orthogonal axial portion 133.

[0083] More specifically, distance D is the distance in the axial x between the inner surfaces 130b and 131b (inner surfaces of the orthogonal portion 133) of a pair of magnetic flux conducting plates 130 and 131, which are opposite to the axial x at the coupling position with the magnetic wire 110.

[0084] The power generation sensor 100 is designed with a detection region 140 located on the side opposite to the magnetic conductor 110 relative to the axis parallel portion 134. A magnetic field generating source is disposed in the detection region 140, which generates the magnetic field to be detected. Figure 1A and Figure 1B The rotation detection device 10 contains a ring-shaped multipole magnet 200. The magnetic poles of the multipole magnet 200 move relative to the power generation sensor 100 to pass through the detection area 140. That is, the detection area 140 is arranged on the magnetic pole movement path of the multipole magnet 200. When the magnetic pole movement path is observed along the axial direction x, the magnetic pole movement path is located on a circumference centered on the rotation axis 300a, and its circumference has a tangent at the detection area 140 that is parallel to the width direction y, which is orthogonal to both the axial direction x and the axial direction z.

[0085] A pair of flux-conducting plates 130, 131 are configured to correct the magnetic field generated by the magnetic field generating source (multipole magnet 200) disposed in the detection region 140 in the space containing the flux-conducting plates 130, 131 into an axial x-field, and apply it to the magnetic conductor 110. An axially parallel portion 134 collects magnetic flux from the surface 134b opposite to the multipole magnet 200 (the detection region opposing surface opposite to the detection region 140, hereinafter referred to as "detection region opposing surface 134b") and guides it into the flux-conducting plates 130, 131. In this embodiment, the detection region opposing surface 134b is a surface parallel to the axial x-field. The detection region opposing surface 134b can be a flat surface parallel to the width direction y, or a cylindrical curved surface matching the cylindrical outer peripheral surface of the multipole magnet 200.

[0086] like Figure 1A and Figure 1B As shown, the axial parallel portion 134, parallel to the axial x-axis of the magnetic wire 110, is located between the magnetic pole surface of the inclined magnetization pattern provided on the outer periphery of the annular multipole magnet 200 and the magnetic wire 110. Therefore, the applied magnetic field is collected by a pair of flux-conducting plates 130 and 131, which are made of soft magnetic material components, and guided to both ends of the magnetic wire 110. Furthermore, the magnetic flux perpendicular to the axial x-axis of the magnetic wire 110 is shielded by the axial parallel portion 134. Therefore, since the applied magnetic field is corrected along the axial x-axis of the magnetic wire 110, the large Backhausen effect can be sufficiently induced, resulting in a high-output signal. The axial x-axis (line length direction) of the magnetic wire 110 of the power generation sensor 100 is arranged parallel to the rotation axis 300.

[0087] The flux-conducting sheets 130 and 131, and the coil 120, which are made of soft magnetic materials, are fixed to the housing (not shown) covering them by adhesive resin, fitting, or other suitable fixing methods. As described above, the two ends 111 and 112 of the magnetic wire 110 are fixed to the wire arrangement portions 130a and 131a, which are formed by two through holes or slots, by resin (not shown). Therefore, the power generation sensor 100 is constructed by fixing and integrating a pair of flux-conducting sheets 130 and 131, the coil 120, and the magnetic wire 110 together.

[0088] The magnetization pattern on the outer periphery of the annular multipole magnet 200 includes multiple (12 in this embodiment) magnetic poles (pole bands) n1, s1, n2, s2... These magnetic poles (pole bands) n1, s1, n2, s2... are arranged circumferentially around the rotation axis 300, forming a band inclined relative to the rotation axis 300. These multiple magnetic poles include N poles n1, n2,... and S poles s1, s2,... arranged alternately along the circumferential direction. In this embodiment, as an example, a structure with 6 N poles n1 to n6 and 6 S poles s1 to s6 is shown; however, the number of magnetic poles can be different.

[0089] When one end of the magnetic conductor 110 of the power generation sensor 100 is aligned with a North pole (more specifically, one end of the magnetic flux conductive plates 130, 131 is aligned with the direction of the rotation radius of the rotation axis 300), the other end of the magnetic conductor 110 is aligned with an adjacent South pole (more specifically, the other end of the magnetic flux conductive plates 130, 131 is aligned with the direction of the rotation radius of the rotation axis 300). The tilt angle θ (pole tilt angle) of the plurality of magnetic poles relative to the rotation axis 300 is determined in such a positional relationship. Figure 1B In the example, one end 112 of the magnetic wire 110 is opposite to the N pole n1, and the other end 111 is opposite to the S pole s1.

[0090] In this embodiment, the tilt angle θ (pole tilt angle) of the plurality of magnetic poles relative to the rotation axis 300 is further determined such that when one of a pair of magnetic flux conducting plates 130, 131 of the power generation sensor 100 is opposite to an N pole (more specifically, opposite in the direction of the rotation radius of the rotation axis 300), the other pair of magnetic flux conducting plates 130, 131 is opposite to an adjacent S pole of that N pole (more specifically, opposite in the direction of the rotation radius of the rotation axis 300). Figure 1B In the example, one magnetic flux conduction plate 131 is opposite to the N pole n1, and the other magnetic flux conduction plate 130 is opposite to the S pole s1.

[0091] This structure enables the pair of magnetic flux conduction plates 130 and 131 of the power generation sensor 100 to conduct magnetic flux from magnetic poles of different polarities, thus realizing a small and high-output power generation sensor 100.

[0092] The preferred design is as follows: when viewing the rotating shaft 300 from the magnetic wire 110 (refer to...) Figure 1B At an angular position of the multipole magnet 200, where the center line 201 of one N pole (n1) is directly opposite to one of the magnetic flux conducting plates (131), the center line 202 of the adjacent S pole (s1) of the N pole (n1) is directly opposite to the other magnetic flux conducting plate (130). Assuming the circumferential distance around the rotation axis 300 from the center line 201 of one N pole (n1) to the center line 202 of the adjacent S pole (s1) is denoted as the pole spacing λ, the above design is equivalent to the tilt angle θ (pole angle) satisfying: in the axial distance equivalent to the distance (D+2W) between the outer ends of a pair of magnetic flux conducting plates 130, 131 (which is almost equal to the total length of the magnetic wire 110), there is a circumferential offset equal to the pole spacing λ. This circumferential distance is preferably equal to the pole spacing λ, but if appropriately determined to be within a range of more than half and less than three-half of the pole spacing λ, a pulse voltage can be output from the power generation sensor 100. Multiple magnetic poles n1, s1, n2, s2, ... are typically formed with equal widths along the circumference around the axis of rotation 300a. In this case, the pole spacing λ is approximately equal to the width of each pole.

[0093] exist Figure 1B In the example, the tilt angle (tilt angle θ) of the tilted pole magnet constituting the multipole magnet 200 is approximately the same as the diagonal of a rectangle, in which the width t of a pair of axially parallel portions 134 is set as the length of one pair of sides, and D+2W is set as the length of the other pair of sides. The circumferential magnetization spacing (pole spacing λ) is approximately equal to the width t of the flux-conducting plates 130 and 131. In this way, since it can accommodate magnets with narrow magnetization spacing, a small rotation detection device can be realized.

[0094] [Model 1]

[0095] Figure 3A , Figure 3B and Figure 3C The results of a two-dimensional magnetic simulation on a cross-section perpendicular to the axis of the magnetic conductor 110 are shown, excluding the magnetic flux conduction plate (comparative example). On the other hand, Figure 4A , Figure 4B and Figure 4C The results of a two-dimensional magnetic simulation on a cross section perpendicular to the axis of the magnetic conductor 110 are shown in the case where the magnetic flux conduction plates 130 and 131 are magnetically coupled at both ends (in an embodiment).

[0096] exist Figure 3A and Figure 4A In this context, the magnetic field source is a magnet 210 magnetized along the arrow direction (one direction of the x-axis) parallel to the magnetic conductor 110. Figure 3B and Figure 4B In this context, the magnetic field source consists of two independent magnets 220, 220, magnetized along the direction of the arrow perpendicular to the magnetic conductor 110 (opposite to the orthogonal axial direction z) and positioned close to the axial x. Figure 3C and Figure 4C In the middle, the magnetic field source is two independent magnets 230, 230 that are magnetized and arranged away from the axis x along the arrow direction perpendicular to the magnetic conductor 110 (opposite to the orthogonal direction z of the axis).

[0097] To ensure that the magnetic flux distribution within the magnetic conductor 110 is uniform over its entire axial length, it is preferable that the magnetic flux enters from one end of the magnetic conductor 110 and exits from the other end. That is, it is preferable that the magnetic flux enters and exits as little as possible at the axial midpoint between the two ends of the magnetic conductor 110 (hereinafter referred to as the "middle section").

[0098] exist Figure 3A and 3B In the magnetic simulation results of the comparative examples shown, the magnetic flux generated by magnets 210 and 220 mostly enters and exits from the middle of the magnetic wire 110. Therefore, the magnetic flux density in the central region of the magnetic wire 110 is higher than that in the two end regions. Furthermore, as... Figure 3C As shown, even when the magnet is not located in the central part (near the axial center position) of the magnetic wire 110, a similar magnetic flux density distribution is achieved.

[0099] from Figures 4A to 4C The magnetic simulation results show that most of the magnetic flux of magnets 210, 220, and 230 is attracted to the flux-conducting plates 130 and 131, which are composed of L-shaped soft magnetic material components, and is magnetized. Although a very small portion of the magnetic flux leaks through the gap (distance L) between a pair of axially parallel portions 134, most of the magnetic flux will pass through the path from one end of the magnetic wire 110 to the other.

[0100] Magnetic flux from magnets 210, 220, and 230 toward the middle portion of magnetic wire 110 is cut off (shielded) by flux-conducting plates 130 and 131, which are made of soft magnetic material components, particularly their axially parallel portions 134. No magnetic flux enters the magnetic wire 110 from its middle portion. More specifically, magnetic flux from magnets 210, 220, and 230 enters from the detection area opposite surface 134b of the axially parallel portion 134 of one flux-conducting plate 131, is conducted within the flux-conducting plate 131, and reaches the second end 112 of the magnetic wire 110. Furthermore, magnetic flux from the first end 111 of the magnetic wire 110 is conducted through the other flux-conducting plate 130 to its axially parallel portion 134, and from its detection area opposite surface 134b to magnets 210, 220, and 230. Therefore, a uniform magnetic flux distribution is formed along the entire length of the magnetic wire 110. That is, a magnetic field of uniform strength parallel to its axis x can be formed along the entire length of the magnetic conductor 110.

[0101] In order to maximize the power obtained, it is very important to start with a state where the magnetization direction of the entire magnetic conductor is consistent, and to reverse the magnetization of the soft magnetic layer throughout the entire magnetic conductor. Figure 3A The structure is equivalent to Figure 9 of Patent Document 1. Figure 3C This is equivalent to the structure shown in Figure 7 of Patent Document 1 and Figure 1 of Patent Document 2. In these structures without a magnetic flux-conducting sheet, the magnetization direction of the magnetic wire is locally inconsistent, resulting in only very small pulse signals.

[0102] like Figure 4A , Figure 4B and Figure 4C As shown, in any of the three different magnetization patterns, in the power generation sensor 100 of the first embodiment, the applied magnetic field is corrected along the axial x-axis of the magnetic conductor 110 by means of the magnetic flux conduction sheets 130, 131 (especially the axial parallel portion 134). As a result, a uniform magnetic field is applied to the entire magnetic conductor 110, enabling the output of a stable high-output pulse signal.

[0103] [Model 2]

[0104] In the first model, magnetic poles of different polarities are opposite to the axis-parallel portion 134 of the first magnetic flux conducting plate 130 and the axis-parallel portion 134 of the second magnetic flux conducting plate 131 (see reference). Figures 4A to 4C In this case, as described above, through the first magnetic flux conducting plate 130 and the second magnetic flux conducting plate 131, the magnetic field is corrected to the axial x of the magnetic conductor 110, generating a uniform magnetic field throughout the magnetic conductor 110.

[0105] On the other hand, a second model is considered, using a cylindrical multipole magnet, i.e., a skewed magnet, as the magnetic field source. The skewed magnet has multiple magnetic poles arranged alternately in the circumferential direction around the central axis of the cylindrical shape on its outer peripheral surface. These multiple magnetic poles have N and S poles arranged alternately in the circumferential direction. Each magnetic pole is inclined relative to the central axis at a predetermined skew angle. In the second model, the central axis of the skewed magnet is parallel to the axial direction x of the magnetic conductor 110, and in the detection region 140, the outer peripheral surface is opposite to the first magnetic flux conducting plate 130 and the second magnetic flux conducting plate 131.

[0106] When the axially parallel portion 134 of the first magnetic flux conducting plate 130 and the axially parallel portion 134 of the second magnetic flux conducting plate 131 are opposite to magnetic poles of different polarities, unlike the first model, the magnetic pole boundary line is inclined relative to the length direction of the magnetic wire 110 at the axial center position 113 of the magnetic wire 110 (refer to...). Figure 1B ).

[0107] A sample of the second model was made, and the oblique pole magnet was rotated around the central axis. Experiments were conducted to study whether it could perform the correction function of the magnetic flux conduction plate in the same way as the first model.

[0108] In the sample of the power generation sensor 100 used in the experiment, the magnetic wire length is 11 mm, the distance D between the orthogonal portions 133 of the magnetic flux conducting plates 130 and 131 is 7 mm, and the distance L between the proximal ends 134a of the pair of parallel portions 134 is 2 mm. The sample structure of the oblique pole magnet used in the experiment has an outer diameter of 14 mm, an inner diameter of 10 mm, a length in the central axis direction of 8 mm, and 12 magnetic poles.

[0109] Figure 5 This is an actual image of the magnetization pattern obtained by observing the oblique pole magnet used for the sample using a magnetic slide. The magnetization spacing is approximately 3.7 mm. This is related to the lateral width of the corresponding magnetic flux conduction plates 130 and 131. Figure 2A The width t) shown is approximately the same as 3.5mm.

[0110] Using these samples, in the configuration of the first embodiment, the output characteristics were confirmed by rotating the slanted pole magnet in both forward and reverse directions. As a result, the power generation sensor 100 outputs a stable high-output pulse signal.

[0111] Thus, even when the magnetic pole boundary line is inclined relative to the length direction of the magnetic conductor 110 at the axial center position 113, it can be confirmed that the function of magnetic field correction along the axial x-axis of the magnetic conductor 110 through the action of the magnetic flux conduction plates 130 and 131 is effective. Neither Patent Document 1 nor Patent Document 2 describes a structure in which the magnetic pole boundary line is inclined relative to the length direction of the magnetic conductor 110 at the axial center position 113.

[0112] Furthermore, the technique of skewed magnetization was primarily established for the magnetization of magnets in electric motors. For example, skewed magnetization can be achieved by rotating a cylindrical magnetic component while simultaneously moving it parallel to the central axis.

[0113] In the sample of the second model of the power generation sensor 100 used in the experiment, the distance D between the orthogonal portions 133 of the first magnetic flux conducting plate 130 and the second magnetic flux conducting plate 131 was set to 7 mm, and the distance L between the proximal ends 134a of these parallel portions 134 was set to 2 mm. In this case, the ratio of the distance L between the proximal ends 134a to the distance D between the pair of orthogonal portions 133 is 29%. The relationship between this distance ratio L / D and the output characteristics was studied.

[0114] Figure 6 The results are shown. The horizontal axis represents the ratio L / D (%), and the vertical axis represents the output pulse height obtained by normalizing the maximum value to 1. The pulse signal height is the average of the absolute values ​​of the positive and negative double pulses when the skewed magnet rotates in one direction (forward rotation) and the positive and negative double pulses when the skewed magnet rotates in the other direction (reverse rotation).

[0115] Depend on Figure 6 It is known that in order to achieve stable high output, the ratio L / D is 5% to 50%. This is presumably due to the narrower spacing (smaller distance L) between the proximal ends 134a when the ratio is less than 5%, resulting in an effect caused by the magnetic circuit formed through this narrower spacing. Furthermore, it is presumably due to the reduced magnetic field strength of the soft magnetic components (magnetic flux conduction plates 130, 131; more specifically, the detection area facing surface 134b) opposite the magnet surface when the ratio L / D exceeds 50%. Additionally, it is presumably because the area of ​​the axially parallel portion 134 of the magnetic flux conduction plates 130, 131 covering the magnetic wire 110 from the magnet decreases, thus also affecting the shielding effect.

[0116] If the ratio L / D is set in the range of 5% or more and 50% or less, the large Backhausen effect characteristic of the magnetic conductor 110 can be sufficiently induced. More preferably, the ratio L / D is set to 15% or more and 45% or less, and even more preferably, it is set to 20% or more and 40% or less.

[0117] [Comparative Example]

[0118] Figure 7A This is a perspective view of the rotation detection device involved in the comparative example. Figure 7B yes Figure 7A A top view of the structure. This rotation detection device is an example of a structure in which the magnetic pole boundary line of the magnetization pattern of the magnet is inclined relative to the length direction of the magnetic wire 110 at the axial center position of the magnetic wire 110. (Refer to the first embodiment). Figure 1A and Figure 1B Compared to the structure of the toroidal multipole magnet 240, the structure of the toroidal multipole magnet 240 is different, and the configuration of the power generation sensor 100 is different relative to the toroidal multipole magnet 240.

[0119] The toroidal multipole magnet 240 has multiple magnetic poles in the circumferential direction around a central axis (rotation axis 300a), which include alternating N and S poles in the circumferential direction. Each magnetic pole is parallel to the central axis, and correspondingly, the magnetic pole boundary lines are parallel to the rotation axis 300.

[0120] Opposite to the outer periphery of the annular multipole magnet 240, the power generation sensor 100 is positioned with the central axis 110a (i.e., the length direction) of the magnetic conductor 110 inclined relative to the rotation axis 300. As a result, the magnetic pole boundary line of the magnetization pattern is inclined relative to the length direction of the magnetic conductor 110 at the axial center position of the magnetic conductor 110.

[0121] However, as Figure 7B As shown, when the annular diameter of the multipole magnet 240 is small, the distance g between the axially parallel portion 134 of the two flux-conducting plates 130, 131 and the magnetic pole surface of the magnet 240 becomes larger. Therefore, it is difficult to obtain the magnetic field strength required to reverse the magnetization direction of the magnetic conductor 110. This problem can be solved by increasing the magnetization spacing or increasing the outer diameter of the ring. However, either solution contradicts the requirement for miniaturization of the device.

[0122] According to the first embodiment using skewed magnets, this problem does not occur. In the first embodiment, the axial x of the magnetic wire 110 of the power generation sensor 100 is parallel to the rotation axis 300a, and the detection area facing surface 134b of the axial parallel portion 134 is directly opposite to the magnetic pole surface of the multipole magnet 200 composed of skewed magnets. This configuration of the power generation sensor 100 allows the pair of axial parallel portions 134 to face magnetic poles of different polarities. Thus, a small-diameter and compact rotation detection device 10 is realized.

[0123] [Second Implementation]

[0124] Figure 8 A rotation detection device according to a second embodiment is shown. In addition to the rotation detection device 10 of the first embodiment, the second embodiment includes a magnetic sensor 400, which identifies the magnetic poles of a multipole magnet 200 composed of skew-pole magnets at predetermined positions in the circumference around the rotation axis 300. This magnetic sensor 400 may, for example, be composed of a Hall effect IC. In this embodiment, a power generation sensor 100 is mounted on a printed circuit board 500 (an example of a board) disposed opposite to the magnetic pole face of the multipole magnet 200. Specifically, the power generation sensor 100 is mounted on the main surface of the printed circuit board 500 opposite to the multipole magnet 200. Therefore, the printed circuit board 500 is positioned between the power generation sensor 100 and the multipole magnet 200, with the flux-conducting plates 130, 131 of the power generation sensor 100 facing the magnetic pole face of the multipole magnet 200 via the printed circuit board 500. Then, in this example, the magnetic sensor 400 is mounted on the printed circuit board 500.

[0125] For example, when the rotation axis 300 rotates in the forward direction, the magnetic sensor 400 becomes active when the power generation sensor 100 outputs a positive signal and becomes inactive when it outputs a negative signal. Similarly, when the rotation axis 300 rotates in the reverse direction, the magnetic sensor 400 becomes inactive when the power generation sensor 100 outputs a positive signal and becomes active when it outputs a negative signal. To achieve these output states, the power generation sensor 100, the multipole magnet 200, and the magnetic sensor 400 are arranged in a relative configuration. Thus, the direction of rotation can be detected by combining the output signals of the power generation sensor 100 and the magnetic sensor 400. The combination of the magnetic sensor 400's on / off state and the rotation axis 300's forward / reverse direction can also be reversed.

[0126] The soft magnetic components constituting the flux conduction plates 130 and 131 are preferably made of a magnetic material with a coercivity below that of the magnetic conductor 110 and high permeability (e.g., relative permeability of 500 or higher). Specifically, materials containing nickel-based ferrite or manganese-based ferrite are preferred. These materials possess excellent characteristics such as low hysteresis, low self-inductance, and low iron loss. Therefore, they have the advantage that when the high-frequency alternating magnetic field generated by the high-speed movement of the magnetic field source is applied to the power generation sensor 100, it will not affect the output characteristics.

[0127] Furthermore, regarding the width of the hole formed through the magnetic flux conducting plates 130 and 131, i.e. the thickness W of the axially orthogonal portion 133 (refer to...) Figure 2A If the thickness W is too large, the configuration width of the coil 120 becomes narrower, thus reducing the efficiency of the large Barkhausen effect in picking up the magnetic wire 110. If it is too small, the magnetic flux becomes narrower. Therefore, based on experimental results, the thickness W is preferably 10% to 20% of the total length of the magnetic wire 110.

[0128] Although the embodiments of the present invention have been described in detail, these are merely specific examples used to illustrate the technical content of the present invention. The present invention should not be construed as being limited to these specific examples, and the scope of the present invention is limited only by the appended claims.

[0129] Label Explanation

[0130] 10: Rotation detection device

[0131] 100: Power Generation Sensor

[0132] 110: Magnetic wire

[0133] 111: First end

[0134] 112: Second end

[0135] 113: Axial center position

[0136] 120: Coil

[0137] 130: Magnetic flux conduction sheet

[0138] 130a: Conductor Configuration Section

[0139] 131: Magnetic flux conduction sheet

[0140] 131a: Conductor Configuration Section

[0141] 133: Orthogonal part of the axis

[0142] 134: Parallel section of shaft

[0143] 134a: Proximity end

[0144] 134b: Detection area opposite face

[0145] 140: Detection area

[0146] 200: Multipole magnet

[0147] 210: Magnet

[0148] 220: Magnet

[0149] 230: Magnet

[0150] 240: Multipole magnet

[0151] 300: Rotation axis

[0152] 400: Magnetic sensor

[0153] 500: Printed substrate

[0154] D: Distance

[0155] L: Distance

[0156] t: width

[0157] W: Thickness

[0158] g: Distance

[0159] x: Axial direction

[0160] y: width direction

[0161] z: Axial orthogonal direction.

[0162] θ: Inclination angle

[0163] λ: Magnetic pole distance.

Claims

1. A rotation detecting device characterized by comprising a ring-shaped multi-pole magnet provided on a rotation axis, and a power generation sensor that detects a magnetic field varying with rotation of the multi-pole magnet, the power generation sensor comprising: a magnetic wire exhibiting a large Barkhausen effect; a coil wound on the magnetic wire; and a pair of magnetic flux conducting sheets composed of soft magnetic members respectively magnetically coupled with both end portions of the magnetic wire, symmetrical to each other with respect to a plane of symmetry set at an axial center position of the magnetic wire, the ring-shaped multi-pole magnet having a magnetization pattern inclined with respect to the rotation axis at an outer peripheral portion, the power generation sensor being opposed to the magnetization pattern of the multi-pole magnet in a posture in which the axis direction of the magnetic wire is parallel to the rotation axis.

2. The rotation detecting device according to claim 1, characterized in that the pair of magnetic flux conducting sheets includes: a pair of axis-orthogonal portions that fix both end portions of the magnetic wire and extend parallel to each other in an axis-orthogonal direction orthogonal to the axis direction from both end portions of the magnetic wire; and a pair of axis-parallel portions that extend from leading end portions of the pair of axis-orthogonal portions in a direction in which they approach each other in the axis direction, the approaching ends being separated by a gap in the axis direction and opposed to each other, the pair of axis-parallel portions being opposed to the magnetization pattern of the multi-pole magnet.

3. The rotation detecting device according to claim 2, characterized in that the distance of the gap in the axis direction is 5 to 50% of the distance in the axis direction between the pair of axis-orthogonal portions at the position of coupling with the magnetic wire.

4. The rotation detecting device according to any one of claims 1 to 3, characterized in that the magnetization pattern includes a plurality of magnetic poles arranged around a circumferential direction of the rotation axis, formed in a band shape inclined with respect to the rotation axis, the plurality of magnetic poles including N poles and S poles alternately arranged in the circumferential direction.

5. The rotation detecting device according to claim 4, characterized in that when one of both end portions of the magnetic wire of the power generation sensor is opposed to one of the N poles, the inclination angle of the plurality of magnetic poles with respect to the rotation axis is determined so that the other of both end portions of the magnetic wire is opposed to one of the S poles adjacent to the N pole.

6. The rotation detecting device according to claim 4, characterized in that when one of the pair of magnetic flux conducting sheets of the power generation sensor is opposed to one of the N poles, the inclination angle of the plurality of magnetic poles with respect to the rotation axis is determined so that the other of the pair of magnetic flux conducting sheets is opposed to one of the S poles adjacent to the N pole.

7. The rotation detecting device according to any one of claims 1 to 6, characterized by further comprising a magnetic sensor that identifies a magnetic pole of the ring-shaped multi-pole magnet at a prescribed position in the circumferential direction around the rotation axis.

8. The rotation detecting device according to any one of claims 1 to 7, characterized by further comprising a substrate disposed between the power generation sensor and the multi-pole magnet, ​ ​ ​ The power generation sensor is mounted on a main surface of the substrate on the side opposite to the multi-pole magnet.

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