Rotation angle detection device

Abstract

To provide a rotation angle detection device capable of detecting the number of rotations of a rotating body and a rotation angle over an entire circumference of the rotating body.SOLUTION: A rotation angle detection device 100 disclosed herein has multiple detection targets 10 comprising multiple first detection targets 11 and one second detection target 12, where the second detection target 12 has a shape different from that of the multiple first detection targets 11.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a rotation angle detection device, and more particularly to a rotation angle detection device including a detection target. [Background technology]

[0002] BACKGROUND ART Conventionally, a rotation angle detection device including a detection target part is known (for example, Patent Document 1).

[0003] The above-mentioned Patent Document 1 discloses a rotation angle sensor (rotation angle detection device) that includes a rotating body and a printed circuit board, where the rotating body includes multiple target portions (detected portions) whose outer or inner peripheral edges are formed in a sinusoidal waveform, and where a first coil and a second coil are formed on the printed circuit board. In Patent Document 1, a first magnetic field generated by the first coil acts on the target portions, and a second magnetic field is generated in the target portions by eddy currents generated in response to the first magnetic field. Furthermore, by facing the target portions, an induced current having a sinusoidal waveform amplitude corresponding to the strength of the second magnetic field is output, and the rotation angle of the rotating body is detected from the induced current having the output sinusoidal waveform amplitude.

[0004] In the above-mentioned Patent Document 1, since the multiple detection parts have the same shape, it is not possible to identify which of the multiple detection parts the detected sine wave corresponds to, and the rotation speed of the rotating body cannot be detected.

[0005] Therefore, in the past, a rotation angle detection device has been used in which a part of a detection target provided on a rotating body is cut out to detect the rotation speed of the rotating body. By cutting out a part of the detection target, the detection target and the second coil do not face each other, so a sine wave is not detected at the position of the cut-out detection target. Therefore, by setting the part where a sine wave is not detected as the reference position for the rotation of the rotating body, the rotation speed is detected from the number of times a sine wave is not detected. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 7347123 Summary of the Invention [Problem to be solved by the invention]

[0007] However, a rotation angle detection device in which a part of the detection target is cut out can detect the rotation speed of a rotating body, but because a sine wave is not detected, it cannot detect the rotation angle of the cut out part. For this reason, it is desirable to be able to detect not only the rotation speed of a rotating body but also the rotation angle over the entire circumference of the rotating body.

[0008] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a rotation angle detection device that is capable of detecting the rotation speed of a rotating body and detecting the rotation angle over the entire circumference of the rotating body. [Means for solving the problem]

[0009] In order to achieve the above object, a rotation angle detection device in one aspect of the present invention comprises a rotating body that is configured to be rotatable and is arranged in a row along the rotation direction, and includes a plurality of detectable parts that protrude radially outward, and a detection part that is arranged opposite the detectable parts and includes a detection coil that detects changes in the magnetic field due to the rotation of the rotating body by detecting a sine wave for each of the plurality of detectable parts, wherein the plurality of detectable parts include a plurality of first detectable parts and one second detectable part, and the second detectable part has a shape different from the shape of the plurality of first detectable parts.

[0010] In a rotation angle detection device according to one aspect of the present invention, as described above, the plurality of detectable portions include a plurality of first detectable portions and one second detectable portion, and the second detectable portion has a shape different from that of the plurality of first detectable portions. As a result, the second waveform of the one second detectable portion differs from the first waveform of the plurality of first detectable portions, making it possible to distinguish between the first waveform and the second waveform. Therefore, the number of rotations of the rotating body can be detected based on the number of times the second waveform is detected, using the second waveform as a reference. Furthermore, by providing the second detectable portion, a sine wave can be detected, unlike when the detectable portion is notched. Therefore, the rotation angle can be detected not only by the first detectable portion but also by the second detectable portion, which serves as a reference when detecting the rotation speed of the rotating body. As a result, it is possible to detect the rotation speed of the rotating body and the rotation angle over the entire circumference of the rotating body.

[0011] In the rotation angle detection device according to the above aspect, the second detectable portion is preferably configured to have a radial length smaller than that of the plurality of first detectable portions, or a rotational width smaller than that of the plurality of first detectable portions.

[0012] With this configuration, the magnitude of the second waveform of the sine wave generated by the second detectable portion can be made smaller than the magnitude of the first waveform of the sine wave generated by the first detectable portion, allowing the rotation speed to be detected based on the number of times the small second waveform is detected. Furthermore, the small size of the second detectable portion can prevent the second detectable portion from interfering with other components, unlike when the second detectable portion is made larger. Here, the smaller the amplitude of the waveform, the more susceptible it is to the influence of external noise. Therefore, by making the second waveform of one second detectable portion smaller than the first waveform of multiple first detectable portions, the number of waveforms with small amplitudes can be reduced compared to when the second waveform is larger than the first waveform, thereby reducing the influence of external noise.

[0013] In the rotation angle detection device according to the above aspect, preferably, one of the plurality of detectable parts and the detection coil has a rectangular shape aligned along the rotation direction, and the other has a sinusoidal shape aligned along the rotation direction, and when the detectable parts have a sinusoidal shape, the second detectable parts are configured to have a smaller radial length than the plurality of first detectable parts, and when the detectable parts have a rectangular shape, the second detectable parts are configured to have a smaller circumferential width than the plurality of first detectable parts.

[0014] With this configuration, one of the plurality of detectable parts and the detection coil has a rectangular shape aligned along the rotation direction, and the other has a sinusoidal shape aligned along the rotation direction, so that the waveform detected by the plurality of detectable parts can easily be made sinusoidal. Furthermore, when the detectable parts have a sinusoidal shape, the second detectable parts are configured to have a smaller radial length than the plurality of first detectable parts, and when the detectable parts have a rectangular shape, the second detectable parts are configured to have a smaller circumferential width than the plurality of first detectable parts, so that the second sinusoidal waveform detected by the second detectable parts can be made smaller in magnitude than the first sinusoidal waveform detected by the first detectable parts.

[0015] In the rotation angle detection device according to the above aspect, preferably, the detectable portion has a sinusoidal shape, the first detectable portion includes a first convex portion and a first concave portion that form the sinusoidal shape, the second detectable portion includes a second convex portion and a second concave portion that form the sinusoidal shape, the radial length from the center of the rotating body to the apex of the second concave portion is configured to be greater than the radial length from the center of the rotating body to the apex of the first concave portion, and the radial length from the center of the rotating body to the apex of the second convex portion is configured to be smaller than the radial length from the center of the rotating body to the apex of the first convex portion.

[0016] Here, changing only one of the radial length from the center of the rotor to the second concave portion and the radial length from the center of the rotor to the second convex portion requires changing the slope of the sine wave, which causes the start and end points of the second waveform of the sine wave to differ from the start and end points of the first waveform of the sine wave, resulting in waveform distortion. Therefore, by reducing both the radial length from the center of the rotor to the second concave portion and the radial length from the center of the rotor to the second convex portion, the shape of the sine wave can be changed without changing the slope of the sine wave, and the start and end points of the second waveform of the sine wave can be aligned with the start and end points of the first waveform of the sine wave, thereby suppressing waveform distortion.

[0017] The rotation angle detection device according to the above aspect may also have the following configuration.

[0018] (Additional note 1) In the rotation angle detection device according to the aforementioned aspect, the second detectable portion has a shape that is different in radial length or rotational width from the shapes of the plurality of first detectable portions.

[0019] By configuring it in this manner, by varying the radial length or rotational width, the shape of the second waveform of the sine wave generated by the second detectable part can be made different from the first waveform of the sine wave generated by the first detectable part, and the rotation speed can be detected based on the number of times the second waveform is detected.

[0020] (Additional note 2) In the rotation angle detection device according to the above aspect, the detectable portion is sinusoidal and includes a concave portion and a convex portion, and the start point and end point of the detectable portion are configured to coincide with the center between the apex of the concave portion and the apex of the convex portion, and the detection coil is configured to detect the sinusoidal wave detected between the start point and the end point of the detectable portion as a sinusoidal wave for one detectable portion.

[0021] With this configuration, when the first and second detectable portions are provided, the start and end points of the detectable portions can be aligned with the center between the apex of the concave portion and the apex of the convex portion, thereby aligning the start and end points of the detected sine wave. As a result, distortion at the boundary between the first waveform detected by the first detectable portion and the second waveform detected by the second detectable portion can be suppressed.

[0022] (Additional note 3) In a rotation angle detection device in which the second detectable portion includes a second concave portion and a second convex portion, the radial length from the center of the rotating body to the apex of the second convex portion is configured to be greater than half the radial length from the center of the rotating body to the apex of the first convex portion.

[0023] By configuring it in this manner, the area of ​​the second convex portion can be made smaller than the first convex portion while being large enough to face (overlap) the detection unit, making it easier to detect a sine wave detected by the second convex portion that is smaller than the sine wave detected by the first convex portion.

[0024] (Additional note 4) In the rotation angle detection device in which the second detectable portion includes a second concave portion and a second convex portion, the detection coil includes a first coil that generates a magnetic field and a second coil that detects a sine wave generated by the detectable portion arranged around the first coil, and the radial length from the center of the rotating body to the apex of the second convex portion is at least half the radial length from the center of the rotating body to the outer peripheral end of the second coil.

[0025] With this configuration, the area of ​​the second convex portion that faces (overlaps) the second coil can be increased, so that the second waveform of the sine wave can be detected with high accuracy.

[0026] (Additional note 5) In a rotation angle detection device in which the second detectable portion includes a second concave portion and a second convex portion, the radial length from a center circle passing through the center between the first convex portion and the first concave portion to the apex of the second concave portion is configured to be smaller than the radial length from the center circle to the apex of the first concave portion, and the radial length from the center circle to the apex of the second convex portion is configured to be smaller than the radial length from the center circle to the apex of the first convex portion.

[0027] With this configuration, the center circle passing through the center between the first convex portion and the first concave portion corresponds to the center position between the peaks and valleys of the first waveform, so by adjusting the size of the second detectable portion with reference to the center circle, it is possible to adjust the size of the second waveform with reference to the center position between the peaks and valleys of the first waveform. As a result, by setting the center positions between the peaks and valleys of the first waveform as the start and end points of the sine wave to be detected, it is possible to align the start and end points of the sine wave, thereby suppressing distortion at the boundary between the first waveform detected by the first detectable portion and the second waveform detected by the second detectable portion. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a diagram showing a state in which a rotation angle detection device according to a first embodiment and a second embodiment is provided on a motor. [Figure 2] 1 is a block diagram showing the configuration of a rotation angle detection device according to a first embodiment and a second embodiment. [Figure 3] FIG. 2 is a top view showing the rotating body of the first embodiment. [Figure 4] 2 is a top view showing a rotating body and a detecting section disposed opposite to the rotating body in the first embodiment. FIG. [Figure 5] 10A and 10B are diagrams illustrating a sine wave detected from a second detection part whose shape has been changed. [Figure 6] FIG. 10 is a top view showing a rotating body of a second embodiment. [Figure 7] FIG. 10 is a top view showing a rotating body and a detecting section disposed opposite to the rotating body according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0030] [First embodiment] The configuration of a rotation angle detection device 100 according to the first embodiment will be described with reference to FIGS.

[0031] As shown in Figures 1 and 2, the rotation angle detection device 100 includes a rotating body 1 and a detection unit 2. The rotation angle detection device 100 is configured to detect the rotation angle of a motor 101. The motor 101 includes a shaft 101a, a stator (not shown), and a rotor (not shown). The motor 101 is housed in a housing 300.

[0032] In the rotation angle detection device 100, an inductive sensor (electromagnetic induction sensor) for detecting the rotation angle of a shaft 101a is configured by a rotating body 1 and a detection unit 2. The inductive sensor is an induction-type sensor that detects changes in a magnetic field caused by the rotation of the rotating body 1 by electromagnetic induction. The shaft 101a is the linearly extending rotation axis of the motor 101. The direction in which the shaft 101a extends is defined as the Z direction.

[0033] The rotating body 1 has a shaft 101a disposed at its center when viewed from the Z direction. The rotating body 1 is configured to rotate integrally with the shaft 101a. The rotating body 1 is inserted through the center of the shaft 101a and fixed to the shaft 101a. Therefore, the rotating body 1 has a through-hole in its center for inserting the shaft 101a. The rotating body 1 is made of a magnetic material such as metal. The rotating body 1 is a plate-shaped member with its thickness direction aligned in the Z direction.

[0034] The rotating body 1 shown in Figures 2 and 3 is configured to be rotatable. The rotating body 1 includes a detection target 10. A plurality of detection targets 10 are provided at intervals along the rotation direction (direction A) of the rotating body 1. The rotating body 1 is configured to rotate with the Z direction as its rotation axis.

[0035] The detectable portions 10 have a sinusoidal shape including concave and convex portions. Specifically, the detectable portions 10 include a plurality of first detectable portions 11 and one second detectable portion 12. The first detectable portions 11 have a first convex portion 11a and a first concave portion 11b. The second detectable portions 12 have a second convex portion 12a and a second concave portion 12b. The outer peripheral edge of the rotating body 1 is configured to have a sinusoidal shape in which convex and concave portions alternate. In the first embodiment, six first detectable portions 11 are provided, so that seven concave and convex portions are provided by the first detectable portions 11 and the second detectable portions 12. The plurality of first detectable portions 11 and one second detectable portion 12 are arranged at predetermined angles θ along the rotation direction (direction A) of the rotating body 1. The predetermined angle θ is a number obtained by dividing 360 degrees by the sum of the plurality of first detectable parts 11 and the one second detectable part 12, and in the first embodiment, it is approximately 52 degrees, obtained by dividing 360 degrees by 7. The plurality of first detectable parts 11 and the one second detectable part 12 are parts located on the outer circumferential surface of the plate-shaped rotating body 1 when viewed from the Z direction. Here, "sine wave shape" includes cases where the shape has a sine wave shape and cases where the shape has a shape close to a sine wave shape.

[0036] The detectable portion 10 protrudes radially outward. The radial direction is the direction from the center C of the rotating body 1 toward the outer periphery, and is perpendicular to the Z direction. Specifically, the first convex portion 11a of the first detectable portion 11 and the second convex portion 12a of the second detectable portion 12 each protrude radially outward along the outer periphery of the rotating body. Furthermore, the first recessed portion 11b and the second recessed portion 12b are recessed radially inward.

[0037] In FIG. 3, as shown by the bold line, the starting point, which is one end of the rotating body 1 in the rotation direction, and the ending point, which is the other end of the rotating body 1 in the rotation direction, are configured to coincide with the center between the apex of the concave portion and the apex of the convex portion in the radial direction. In other words, they are the centers when connecting the apex of the concave portion and the apex of the convex portion along the outer periphery of the rotating body 1. In the rotation direction A, the starting point is the center c1 between the apex of the concave portion and the apex of the convex portion, passes through the center c2 between the apex of the concave portion and the apex of the convex portion located next to the center c1, and the ending point is the center c3 between the apex of the concave portion and the apex of the convex portion located next to the center c1. A concave portion is formed between the centers c1 and c2, and a convex portion is formed between the centers c2 and c3. FIG. 3 shows one of the multiple first detectable portions 11 and a second detectable portion 12. The starting point and ending point of the detectable portion 10 located adjacent to the center c1 in the rotation direction coincide with each other.

[0038] (Shape of the second detection target part) 3 and 5, the second detectable portion 12 has a shape that differs in radial length or rotational width from the shape of the first detectable portion 11 so as to detect a second sine wave waveform W2 that is different from the first sine wave waveform W1 detected by each of the first detectable portions 11. In the first embodiment, the radial length of the second detectable portion 12 is configured to be smaller than the radial length of the first detectable portion 11.

[0039] As shown in FIGS. 3 and 5, the radial length r2 from the center C of the rotating body 1 to the apex of the second concave portion 12b is configured to be greater than the radial length r1 from the center C of the rotating body 1 to the apex of the first concave portion 11b so that the valleys and peaks of the second waveform W2 of the sine wave detected for the second detection target 12 approach the centers of the valleys and peaks. Note that in FIG. 5, the centers of the valleys and peaks (lines representing amplitude = 0) are indicated by bold lines. Furthermore, the radial length R2 from the center C of the rotating body 1 to the apex of the second convex portion 12a is configured to be smaller than the radial length R1 from the center of the rotating body 1 to the apex of the first convex portion 11a. Furthermore, the radial length R2 from the center C of the rotating body 1 to the apex of the second convex portion 12a is configured to be greater than half the radial length R1 from the center C of the rotating body 1 to the apex of the first convex portion 11a. As an example, the radial length R2 from the center C of the rotating body 1 to the apex of the second convex portion 12a is set to be 70% or more of the radial length R1 from the center C of the rotating body 1 to the apex of the first convex portion 11a. This allows the amplitude of the sine wave detected from the second detectable portion 12 to be 80% or more of the amplitude of the sine wave detected from the first detectable portion 11. Note that the apex of the first convex portion 11a and the apex of the second convex portion 12a refer to the highest height positions. The apex of the first recessed portion 11b and the apex of the second recessed portion 12b refer to the lowest height positions (valley bottoms).

[0040] As shown in FIGS. 3 and 4 , the radial length d2 from a center circle 50 passing through the center between the vertices of the first convex portion 11a and the first concave portion 11b to the vertex of the second concave portion 12b is smaller than the radial length d1 from the center circle 50 to the vertex of the first concave portion 11b. The radial length t1 from the center circle 50 to the vertex of the second convex portion 12a is smaller than the radial length t2 from the center circle 50 to the vertex of the first convex portion 11a. Furthermore, the radial length R2 from the center of the rotor 1 to the vertex of the second convex portion 12a is at least half the radial length R3 from the rotor 1 to the outer circumferential end of the second coil 20b. For example, the radial length R2 from the center of the rotor 1 to the vertex of the second convex portion 12a is at least 70% of the radial length R3 from the rotor 1 to the outer circumferential end of the second coil 20b. In FIG. 3 , the center circle 50 is indicated by a dashed line.

[0041] (Configuration of the detection unit) The detection unit 2 includes a detection coil 20 and a sensor circuit (not shown). The detection unit 2 is fixed to a housing 300 (see FIG. 1) that houses the motor 101. The detection coil 20 includes a first coil 20a and a second coil 20b. The first coil 20a is arranged to surround the multiple second coils 20b. The first coil 20a and the second coil 20b are each formed in a rectangular shape. Note that the rectangular shape includes not only a rectangle but also a trapezoid or a sector shape with arc-shaped sides. The detection unit 2 is arranged facing the detection target 10. Specifically, the first coil 20a and the second coil 20b face the detection target 10. The detection unit 2 is configured to detect a change in the magnetic field caused by the rotation of the rotating body 1 by detecting one sine wave for each detection target 10. Specifically, the detection coil 20 detects the change in the magnetic field caused by the rotation of the rotating body 1. The detector 2 detects the rotation angle of the shaft 101a based on the change in the magnetic field.

[0042] Four second coils 20b, 201b to 204b, are provided. The four second coils 20b are arranged along the circumferential direction while being collectively surrounded by the first coil 20a. Of the four second coils 20b, the two second coils 20b arranged at both ends in the rotational direction and the other two second coils 20b have coil patterns with winding directions that are different from each other. The second coils 20b with winding directions that are different from each other are connected in series.

[0043] 2 and 4, the detection unit 2 is disposed opposite the detection target 10 in the Z direction. The detection unit 2 is configured to detect a change in the magnetic field caused by the rotation of the rotating body 1 by detecting one sine wave for each of the detection target 10. The detection coil 20 is configured to detect the sine wave detected between the start point and the end point of the detection target 10 as the sine wave for one detection target 10. In FIG. 4, the portion of the detection target 10 that overlaps with the detection coil 20 in the Z direction is represented by a dashed line.

[0044] <Detection of rotation angle using detection coil> The first coil 20a is configured to generate an AC magnetic field for detecting the rotation angle of the shaft 101a. Specifically, the first coil 20a is configured to be excited by AC power supplied from the sensor circuit unit. The excited first coil 20a is configured to generate a magnetic field (AC magnetic field) that oscillates in the direction of the rotation axis of the rotor 1 (Z direction). The first coil 20a applies the generated magnetic field toward the rotor 1.

[0045] The second coil 20b and the first coil 20a are magnetically coupled by a magnetic field generated from the first coil 20a toward the rotating body 1. As a result, different alternating currents are induced to flow based on a change in the strength of the magnetic field that accompanies a change in the distance between the second coil 20b and the detected part 10 of the rotating body 1.

[0046] In the rotation angle detection device 100, when the distance between any of the second coils 20b and any of the convex portions of the detection target 10 decreases due to rotation of the rotating body 1, the area of ​​the second coil 20b facing the detection target 10 increases. Therefore, the second coil 20b detects magnetic flux caused by eddy currents in the detection target 10 of the rotating body 1 more strongly, resulting in a larger induced current in the second coil 20b. Furthermore, when the distance between any of the second coils 20b and any of the convex portions of the detection target 10 increases, the area of ​​the second coil 20b facing the detection target 10 decreases. Therefore, the second coil 20b detects magnetic flux caused by eddy currents in the detection target 10 of the rotating body 1 less strongly, resulting in a smaller induced current. In this way, each of the second coils 20b detects changes in the magnetic field generated by the first coil 20a.

[0047] Here, first coil 20a is arranged so as to extend in an arc shape along the circumferential direction over a distance greater than one period of the sine wave of the outer peripheral edge of rotating body 1. In other words, first coil 20a is arranged so as to collectively surround at least one peak and at least one valley on the outer peripheral edge of rotating body 1.

[0048] The rotation angle detection device 100 generates an eddy current by applying an AC magnetic field generated by the first coil 20a to the first detectable portion 11 and the second detectable portion 12 of the rotating body 1. An induced current flows in the second coil 20b due to the magnetic field generated by the eddy current generated by the first detectable portion 11 and the second detectable portion 12 of the rotating body 1. The induced current flowing in the second coil 20b is output to a sensor circuit unit as a detection result. The sensor circuit unit generates a rotation angle signal indicating the rotation angle based on the acquired detection result. The rotation angle detection device 100 outputs the rotation angle signal generated by the sensor circuit unit to another component (for example, a control unit).

[0049] A sine wave (sine wave) and a cosine wave (cosine wave) are obtained from the obtained induced current, and the angle is calculated by calculating the tangent (tan) from the values ​​of the sine wave (sine wave) and the cosine wave (cosine wave), thereby obtaining the rotation speed and rotation angle. The rotation angle detection device 100 of the first embodiment can detect the rotation speed of the shaft 101a by using the second detection target 12 as a reference point. Specifically, the period from when a low-height portion of the sine wave is detected to when the next is detected can be considered as one rotation of the shaft 101a.

[0050] Figure 5 shows a sine wave when the radial length from the apex of the second convex portion 12a to the apex of the second concave portion 12b is set to 0.8 times the height from the apex of the first convex portion 11a to the apex of the first concave portion 11b.

[0051] 5 shows an example of a waveform obtained when the radial lengths of the second convex portion 12a and the second concave portion 12b of the second detectable portion 12 are reduced. The heights of the peaks of the first waveform W1 of the sine wave detected by the multiple first detectable portions 11 are the same. In the example of FIG. 5, the output voltage is 1 at the peaks of the first waveform W1 of the sine wave detected by the multiple first detectable portions 11. In the example of FIG. 5, by reducing the radial length of the second convex portion 12a, the output voltage is 0.6 at the peaks of the second waveform W2 of the sine wave detected by one second detectable portion 12, which is smaller in height than the peaks of the first detectable portion 11. Furthermore, the output voltage of the sine wave detected at the valleys of the first waveform W1 of the sine wave detected by the multiple first detectable portions 11 is -1. Furthermore, the depths of the valleys of the first waveform W1 of the sine wave detected by the multiple first detectable portions 11 are the same. At the valleys of the second waveform W2 of the sine wave detected at one second detectable portion 12, the output voltage is -0.6 by changing the radial length of the second recessed portion 12b, making the valleys deeper than those of the first waveform W1. This makes it possible to distinguish between the second waveform W2 and the first waveform W1, and therefore, using the second detectable portion 12 as a reference point, it is possible to obtain the rotation speed of the rotating body 1 according to the number of times the second waveform W2 is detected. Furthermore, because the second waveform W2 is detected, it is also possible to detect the rotation angle of the rotating body 1 at the second detectable portion 12, which is used as the reference point.

[0052] (Effects of the first embodiment) In the first embodiment, the following effects can be obtained.

[0053] In the first embodiment, as described above, the multiple detectable portions 10 include multiple first detectable portions 11 and one second detectable portion 12, and the second detectable portion 12 has a shape different from the shapes of the multiple first detectable portions 11. As a result, the second waveform W2 of the single second detectable portion 12 differs from the first waveform W1 of the multiple first detectable portions 11, making it possible to distinguish between the first waveform W1 and the second waveform W2. Therefore, the rotation speed of the rotating body 1 can be detected based on the number of times the second waveform W2 is detected, using the second waveform W2 as a reference. Furthermore, by providing the second detectable portion 12, a sine wave can be detected, unlike when the detectable portion is notched. Therefore, the rotation angle can be detected not only by the first detectable portion 11 but also by the second detectable portion 12, which serves as a reference when detecting the rotation speed of the rotating body 1. As a result, it is possible to detect the rotation speed of the rotating body 1 and the rotation angle over the entire circumference of the rotating body 1.

[0054] Furthermore, in the first embodiment, as described above, the second detectable portion 12 is configured to have a smaller radial length than the multiple first detectable portions 11 or a smaller rotational width than the multiple first detectable portions 11. This allows the magnitude of the second waveform W2 of the sine wave generated by the second detectable portion 12 to be smaller than the magnitude of the first waveform W1 of the sine wave generated by the first detectable portion 11, thereby enabling the rotation speed to be detected based on the number of times the small waveform W2 is detected. Furthermore, the small size of the second detectable portion 12 can prevent the second detectable portion 12 from interfering with other components, unlike when the second detectable portion 12 is larger. Here, the smaller the waveform amplitude, the more susceptible it is to the influence of disturbance noise. Therefore, by making the second waveform W2 of one second detectable portion 12 smaller than the first waveform W1 of the multiple first detectable portions 11, the number of waveforms with small amplitudes can be reduced compared to when the second waveform W2 is larger than the first waveform W1, thereby reducing the influence of disturbance noise.

[0055] Furthermore, in the first embodiment, as described above, one of the plurality of detectable parts 10 and the detection coil 20 is configured to have a rectangular shape aligned along the rotation direction, while the other is configured to have a sinusoidal shape aligned along the rotation direction, and when the detectable parts 10 have a sinusoidal shape, the second detectable parts 12 are configured to have a smaller radial length than the plurality of first detectable parts 11, and when the detectable parts 10 have a rectangular shape, the second detectable parts 12 are configured to have a smaller circumferential width than the plurality of first detectable parts 11. As a result, by configuring one of the plurality of detectable parts 10 and the detection coil 20 to have a rectangular shape aligned along the rotation direction, while the other is configured to have a sinusoidal shape aligned along the rotation direction, the waveform detected by the plurality of detectable parts 10 can easily be made sinusoidal. Furthermore, when the detectable portion 10 has a sinusoidal shape, the second detectable portion 12 is configured to have a smaller radial length than the multiple first detectable portions 11, and when the detectable portion 10 has a rectangular shape, the second detectable portion 12 is configured to have a smaller circumferential width than the multiple first detectable portions 11, thereby making it possible to make the sinusoidal second waveform W2 detected by the second detectable portion 12 smaller in magnitude than the sinusoidal first waveform W1 detected from the first detectable portion 11.

[0056] Furthermore, in the first embodiment, as described above, the detectable portion 10 has a sinusoidal shape, the first detectable portion 11 includes a first convex portion 11a and a first concave portion 11b that form the sinusoidal shape, the second detectable portion 12 includes a second convex portion 12a and a second concave portion 12b that form the sinusoidal shape, and the radial length r2 from the center C of the rotating body 1 to the apex of the second concave portion 12b is configured to be greater than the radial length r1 from the center C of the rotating body 1 to the apex of the first concave portion 11b, and the radial length R2 from the center C of the rotating body 1 to the apex of the second convex portion 12a is configured to be smaller than the radial length R1 from the center C of the rotating body 1 to the apex of the first convex portion 11a. Here, if only one of the radial length from the center of the rotor 1 to the second recessed portion 12b or the radial length from the center of the rotor 1 to the second convex portion 12a is changed, the slope of the sine wave must be changed, which causes the start and end points of the second sine wave W2 to be misaligned with the start and end points of the first sine wave W1, resulting in waveform distortion. Therefore, by reducing both the radial length r2 from the center C of the rotor 1 to the second recessed portion 12b and the radial length R2 from the center C of the rotor 1 to the second convex portion 12a, the shape of the sine wave can be changed without changing the slope of the sine wave. This allows the start and end points of the second sine wave W2 to be aligned with the start and end points of the first sine wave W1, thereby suppressing waveform distortion.

[0057] Furthermore, in the first embodiment, as described above, second detectable portions 12 have a shape that differs in radial length or rotational width from the shapes of the plurality of first detectable portions 11. By making the radial length or rotational width different, the shape of second waveform W2 of the sine wave generated by second detectable portions 12 can be made different from the shape of first waveform W1 of the sine wave generated by first detectable portions 11, and therefore the rotation speed can be detected based on the number of times that second waveform W2 is detected.

[0058] In the first embodiment, as described above, the detectable portion 10 has a sine wave shape including a concave portion and a convex portion. The start and end points of the detectable portion 10 are configured to coincide with the center between the apex of the concave portion and the apex of the convex portion. The detection coil 20 is configured to detect a sine wave detected between the start and end points of the detectable portion 10 as a sine wave for one detectable portion 10. As a result, when the first detectable portion 11 and the second detectable portion 12 are provided, the start and end points of the detectable portion 10 can be aligned by aligning the start and end points of the detectable portion 10 with the center between the apex of the concave portion and the apex of the convex portion. As a result, distortion at the boundary between the first waveform W1 detected by the first detectable portion 11 and the second waveform W2 detected by the second detectable portion 12 can be suppressed.

[0059] Furthermore, in the first embodiment, as described above, the radial length R2 from the center C of the rotating body 1 to the apex of the second convex portion 12a is configured to be larger than half the radial length R1 from the center C of the rotating body 1 to the apex of the first convex portion 11a. This makes it possible to make the area of ​​the second convex portion 12a smaller than that of the first convex portion 11a, while still making it large enough to face (overlap) the detection unit 2, thereby making it easier to detect the sine wave detected by the second convex portion 12a, which is smaller than the sine wave detected by the first convex portion 11a.

[0060] Furthermore, in the first embodiment, as described above, the detection coil 20 includes the first coil 20a that generates a magnetic field and the second coil 20b that detects a sine wave generated by the detection target 10 that is disposed around the first coil 20a, and the radial length R2 from the center C of the rotating body 1 to the apex of the second convex portion 12a is equal to or greater than half the radial length R3 from the center C of the rotating body 1 to the outer peripheral end of the second coil 20b. This increases the area of ​​the second convex portion 12a that faces (overlaps) the second coil 20b, thereby enabling the second waveform W2 of the sine wave to be detected with high accuracy.

[0061] Furthermore, in the first embodiment, as described above, the radial length d2 from the center circle 50 passing through the center between the first convex portion 11a and the first concave portion 11b to the apex of the second concave portion 12b is configured to be smaller than the radial length d1 from the center circle 50 to the apex of the first concave portion 11b, and the radial length t2 from the center circle 50 to the apex of the second convex portion 12a is configured to be smaller than the radial length t1 from the center circle 50 to the apex of the first convex portion 11a. As a result, the center circle 50 passing through the center between the first convex portion 11a and the first concave portion 11b corresponds to the center position between the peaks and valleys of the first waveform W1, and therefore, by adjusting the size of the second detectable portion 12 based on the center circle 50, the size of the second waveform W2 can be adjusted based on the center position between the peaks and valleys of the first waveform W1. As a result, by making the center position between the peaks and valleys of the first waveform W1 the starting point and ending point of the detected sine wave, the starting point and ending point of the sine wave can be aligned, thereby preventing distortion from occurring at the boundary between the first waveform W1 detected by the first detectable portion 11 and the second waveform W2 detected by the second detectable portion 12.

[0062] [Second embodiment] Next, the configuration of a rotation angle detection device 200 according to a second embodiment of the present invention will be described with reference to Figures 1, 6 and 7. The second embodiment differs from the first embodiment in the shape of the detected part 210 and the shape of the detection coil 220.

[0063] 6, the rotating body 201 includes, when viewed from the Z direction, an annular base portion 213 extending along the outer circumferential surface of the shaft 101a, and a first detectable portion 211 and a second detectable portion 212 protruding radially from the base portion 213. Note that in FIG. 6, the base portion 213 is hatched for ease of understanding.

[0064] The first detectable portion 211 has a rectangular shape extending in the rotation direction of the rotating body 201. The rectangular shape includes not only a rectangle but also a trapezoid or a sector shape with some of the sides being arcuate. The first detectable portion 211 has a pair of linear surfaces 211a and a pair of arcuate surfaces 211b. The pair of linear surfaces 211a extend linearly in the radial direction when viewed from the Z direction and face each other in the rotation direction (direction A). When viewed from the Z direction, one arcuate surface 211b is an arcuate surface centered on the center C of the shaft 101a and faces the boundary between the first detectable portion 211 and the base portion 213 in the radial direction. The one arcuate surface 211b connects the radial ends of the pair of linear surfaces 211a when viewed from the Z direction.

[0065] The second detectable portion 212 has a rectangular shape extending in the rotation direction of the rotating body 201. The rectangular shape includes, in addition to a rectangle, a trapezoid, or a sector shape with some of its sides arcuate. The second detectable portion 212 has a pair of linear surfaces 212a and a pair of arcuate surfaces 212b. The pair of linear surfaces 212a extend linearly in the radial direction when viewed from the Z direction and face each other in the rotation direction (direction A). When viewed from the Z direction, one arcuate surface 212b is an arcuate surface centered on the center C of the shaft 101a and faces the boundary between the second detectable portion 212 and the base portion 213 in the radial direction. The one arcuate surface 212b connects the radial ends of the pair of linear surfaces 212a when viewed from the Z direction.

[0066] The first detectable portion 211 and the second detectable portion 212 have the same amount of protrusion radially outward from the base portion 213. That is, in the Z direction, the length of the pair of linear surfaces 211a of the first detectable portion 211 and the length of the pair of linear surfaces 212a of the second detectable portion 212 are the same.

[0067] The width w2 in the rotational direction of the second detectable portion 212 is configured to be smaller than the width w1 in the rotational direction of the first detectable portion 211. In other words, the width of the arcuate surface 212b of the second detectable portion 212 and the spacing in the rotational direction between the pair of linear surfaces 212a are smaller than the width of the arcuate surface 212b of the second detectable portion 212 and the spacing in the rotational direction between the pair of linear surfaces 212a. Here, the width in the rotational direction is the length of an arc drawn around the center C of the rotating body 201.

[0068] As shown in Fig. 7, the second coil 220b of the detection coil 220 has a sinusoidal wave shape aligned along the rotation direction. The first coil 220a has a rectangular shape. The first coil 220a is disposed so as to surround the second coil 220b. In Fig. 7, the portion of the detected part 210 that overlaps with the detection coil 220 in the Z direction is represented by a dashed line.

[0069] 6, in the second embodiment, the second coil 220b has a sinusoidal shape, and therefore the detected waveform is formed in a sinusoidal shape. Also, the width w2 in the rotational direction of the second detectable portion 212 is configured to be smaller than the width w1 in the rotational direction of the first detectable portion 211, and therefore the magnitude of the detected sinusoidal waveform is smaller.

[0070] The other configurations of the second embodiment are the same as those of the first embodiment.

[0071] (Effects of the second embodiment) In the second embodiment, as described above, the plurality of detectable portions 210 include a plurality of first detectable portions 211 and one second detectable portion 212, and the second detectable portion 212 has a shape different from that of the plurality of first detectable portions 211. As a result, the second waveform W2 of the one second detectable portion 212 differs from the first waveform W1 of the plurality of first detectable portions 211, making it possible to distinguish between the first waveform W1 and the second waveform W2. Therefore, the number of rotations of the rotating body 201 can be detected based on the number of times the second waveform W2 is detected, using the second waveform W2 as a reference. Furthermore, by providing the second detectable portion 212, a sine wave can be detected, unlike when the detectable portion is notched. Therefore, the rotation angle can be detected not only by the first detectable portion 211 but also by the second detectable portion 212, which serves as a reference when detecting the rotation speed of the rotating body 201. As a result, it is possible to detect the rotation speed of the rotating body 201 and the rotation angle over the entire circumference of the rotating body 201.

[0072] The other effects of the second embodiment are the same as those of the first embodiment.

[0073] [Variations] The above-described embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the description of the above-described embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0074] For example, in the first and second embodiments, the rotation angle detection device is configured to detect the rotation angle of a motor, but the present invention is not limited to this. In the present invention, the rotation angle detection device may be configured to detect the rotation angle of a rotating body such as a crankshaft or camshaft of a vehicle.

[0075] In the first and second embodiments, the radial length from the center of the rotor to the apex of the second convex portion is at least half the radial length from the rotor 1 to the outer peripheral end of the second coil, but the present invention is not limited to this. In the present invention, as long as the second convex portion and the second coil are configured to partially overlap, the radial length from the center of the rotor to the apex of the second convex portion may be less than half the radial length from the rotor 1 to the outer peripheral end of the second coil.

[0076] In the first and second embodiments, the radial length from the center of the rotor to the apex of the second recessed portion is greater than the radial length from the center of the rotor to the apex of the first recessed portion, and the radial length from the center of the rotor to the apex of the second convex portion is smaller than the radial length from the center of the rotor to the apex of the first convex portion. However, the present invention is not limited to this. In the present invention, the radial length from the center of the rotor to the apex of the second recessed portion may be greater than the radial length from the center of the rotor to the apex of the first concave portion, or the radial length from the center of the rotor to the apex of the second convex portion may be smaller than the radial length from the center of the rotor to the apex of the first convex portion.

[0077] In the first embodiment, the second detectable portion has a radial length smaller than that of the first detectable portions, but the present invention is not limited to this. In the present invention, the second detectable portion may have a radial length greater than that of the first detectable portions.

[0078] In the first embodiment, the plurality of detectable portions have a sinusoidal shape aligned along the rotation direction, and the second detectable portion has a different radial length than the plurality of first detectable portions. However, the present invention is not limited to this. In the present invention, the plurality of detectable portions may have a rectangular shape aligned along the rotation direction, and the second detectable portion may have a radial length that is smaller or larger than the plurality of first detectable portions.

[0079] In the second embodiment, the second detectable portion is configured to have a smaller width in the rotation direction than the plurality of first detectable portions, but the present invention is not limited to this. In the present invention, the second detectable portion is configured to have a larger width in the rotation direction than the plurality of first detectable portions.

[0080] In the second embodiment, the plurality of detectable portions have rectangular shapes aligned along the rotational direction, and the second detectable portions have a smaller width in the rotational direction than the plurality of first detectable portions. However, the present invention is not limited to this. In the present invention, the plurality of detectable portions may have sinusoidal shapes aligned along the rotational direction, and the second detectable portions may be configured to have a larger or smaller width in the rotational direction than the plurality of first detectable portions. [Explanation of symbols]

[0081] 1: Rotating body, 2: Detecting portion, 10: Detected portion, 11, 211: First detected portion, 11a: First convex portion, 11b: First concave portion, 12, 212: Second detected portion, 12a: Second convex portion, 12b: Second concave portion, 20: Detection coil, 100, 200: Rotation angle detection device

Claims

1. a rotating body configured to be rotatable, provided with a plurality of detection parts arranged in a rotation direction and protruding radially outward; a detection unit including a detection coil disposed opposite the detection target parts and detecting a sine wave for each of the detection target parts to detect a change in a magnetic field caused by rotation of the rotating body; the plurality of detection targets include a plurality of first detection targets and one second detection target, A rotation angle detection device, wherein the second detection target portion has a shape different from the shapes of the plurality of first detection target portions.

2. 2. The rotation angle detection device according to claim 1, wherein the second detectable portion is configured to have a radial length smaller than that of the plurality of first detectable portions, or a rotational width smaller than that of the plurality of first detectable portions.

3. one of the plurality of detection portions and the detection coil has a rectangular shape aligned along the rotation direction, and the other has a sinusoidal shape aligned along the rotation direction, When the detection target portion has a sinusoidal shape, the second detection target portion is configured to have a radial length smaller than that of the plurality of first detection target portions, 2. The rotation angle detection device according to claim 1, wherein when the detection target portion has a rectangular shape, the second detection target portion is configured to have a smaller circumferential width than the plurality of first detection target portions.

4. The detected portion has a sinusoidal shape, the first detected portion includes a first convex portion and a first concave portion that form a sinusoidal wave shape, the second detection portion includes a second convex portion and a second concave portion that form a sinusoidal wave shape, 4. The rotation angle detection device of claim 3, wherein the radial length from the center of the rotating body to the apex of the second concave portion is configured to be greater than the radial length from the center of the rotating body to the apex of the first concave portion, and the radial length from the center of the rotating body to the apex of the second convex portion is configured to be smaller than the radial length from the center of the rotating body to the apex of the first convex portion.

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