JP5656900B2 - Rotation angle measuring device and rotating machine equipped with the rotation angle measuring device - Google Patents

Description

  The present invention relates to a rotation angle measuring device using a magnetic sensor and a rotary machine equipped with the rotation angle measuring device, and more particularly to a rotation angle measuring device capable of obtaining an accurate rotation angle by absorbing a mounting error of the magnetic sensor, and The present invention relates to a rotary machine equipped with this rotation angle measuring device.

  A rotating body (rotation angle) is measured by installing a magnetic flux generator, such as a magnet, on the rotating body, and installing a magnetic sensor at a position where the magnetic flux generated by the magnetic flux generator can reach. It is known that it can be done. Specifically, when the rotating body rotates, the direction of the magnetic flux generated by the magnetic flux generator also rotates, so the rotational position (rotation angle) of the rotating body can be measured by detecting the direction of the magnetic flux with a magnetic sensor. This is used in many industrial fields as a rotation angle measuring device.

  Here, the magnetic sensors are roughly classified into a magnetic field strength measurement sensor that outputs a signal corresponding to the magnetic field strength and a magnetic field direction measurement sensor that outputs a signal corresponding to the magnetic field direction. The magnetic field direction measuring sensor is also called a vector type magnetic sensor because it measures the magnetic field direction as a vector.

  Magnetic field direction measurement sensors include (1) a Hall-effect element and (2) a magneto-resistance element as a magnetic field sensitive element. The details will be described below.

  First, the Hall effect element itself is an element that outputs a signal according to the magnetic field strength. However, using a plurality of Hall effect elements, the spatial difference in magnetic field strength is measured, and the cosine component (COS component) and sine component (SIN component) in the magnetic field direction are detected, so that the direction of the magnetic field is met. Output signal. Thus, since the signal according to the magnetic field direction is output, it can be said that this is a magnetic field direction measurement sensor.

  In addition, there is a sensor that measures the magnetic field direction by using a magnetic body having an appropriate shape and a plurality of Hall effect elements. This type of magnetic sensor converts a magnetic field direction into a magnetic field strength difference by converging a magnetic field with a magnetic material, and measures the difference with a plurality of Hall effect elements. Since this also outputs a signal corresponding to the magnetic field direction, it can be said to be a magnetic field direction measurement sensor.

  As described above, various types of magnetic sensors of a magnetic field direction measuring sensor that are configured by Hall effect elements and output a signal corresponding to the magnetic field direction are known.

  Next, the magnetoresistive element is an element whose electric resistance changes according to the strength of the magnetic field and the direction of the magnetic field. The magnetoresistive elements include anisotropic magnetoresistive elements (Anisotropic Magneto-resistance, hereinafter referred to as “AMR elements”), giant magnetoresistive elements (Giant Magneto-resistance, hereinafter referred to as “GMR elements”), tunnel magnetoresistive elements ( Tunneling Magneto-resistance (hereinafter referred to as “TMR element”).

  The electrical resistance of the AMR element changes according to the angle formed by the direction of the magnetic field and the direction of the current. By appropriately combining elements with different current directions, a signal corresponding to the magnetic field angle is output. The GMR element has a configuration in which a fixed magnetic layer and a free magnetic layer are stacked via a spacer layer. A signal corresponding to the magnetic field angle is output by appropriately combining elements in which the spin direction (magnetization direction) of the fixed magnetization layer is changed. A GMR element having a fixed magnetic layer is also called a spin-valve type GMR element.

  One advantage of the rotation angle sensor using a magnetic sensor is that it is a non-contact type. The non-contact type means that the sensor that is a detector for detecting the rotational position and the rotating body are not in mechanical contact with each other. Even when used for a long period of time, mechanical wear does not occur and a highly reliable sensor can be obtained.

  A rotation angle sensor using a multipolar magnetized magnet as a magnetic flux generator is known. When a (2 × p) pole magnetized magnet is used, the direction of the magnetic field in the rotation surface of the magnet rotates only p times when the magnet rotates once. For example, consider the case of p = 4, that is, the case of using an octupole magnet. When the magnet rotates 90 °, the magnetic field direction rotates once. Therefore, when the rotation angle is obtained by measuring the magnetic field direction, the rotation angle can be measured with four times the accuracy. Thus, when a multipolar magnetized magnet is used, there exists an advantage that a highly accurate rotation angle measuring device may be realizable.

  However, the rotation angle measuring device using a multipolar magnet has a problem that it is affected by the magnetizing error of the magnet. In the magnet magnetization process, an error is likely to occur in the magnetized characteristics, that is, the magnetic field distribution generated by the magnet.

  Here, errors include systematic errors and individual errors. The systematic error is an error inherent to the magnetizing apparatus used, and is a deviation from an ideal magnetic field distribution. This is a reproducible error in the same magnetization process (magnetization lot). On the other hand, the individual error is an error that varies from individual to individual even when manufactured in the same magnetization process (magnetization lot). In general, the magnetizing error of a magnet includes both a systematic error and an individual error.

  In a rotation angle measuring device using a magnetic sensor, the measured magnetic field angle is converted into a rotation angle based on the relationship between the rotation angle of the magnetic flux generator and the magnetic field angle. Therefore, if there is a magnetization error, there is a problem that a measurement error occurs in the rotation angle.

  In order to eliminate this problem, a rotation angle measuring device that corrects a magnetization error is disclosed in Japanese Patent Laying-Open No. 2011-002311 (Patent Document 1). However, in the case of a multipolar magnet, there has been a problem in applying this correction method. This point will be described below.

  In a (2 × p) polar magnet, the magnetic field direction rotates p times during one rotation of the magnet. In the following, the rotation angle of the magnet is referred to as “mechanical angle”, and the angle in the direction of the magnetic field is referred to as “magnetic field angle”. Now, one period of the magnetic field angle is called a “sector”. That is, the magnetic field angle distribution (profile, the correlation between the magnetic field angle and the mechanical angle) when the (2 × p) polar magnet makes one rotation has p sectors. The magnetic field angle distribution in the sector (correlation between magnetic field angle and mechanical angle) is the same. Therefore, in the case of an ideally magnetized magnet, the rotation angle can be obtained from the measured magnetic field angle.

  However, if there is a magnetization error, the magnetic field angle distribution changes for each sector. For this reason, the correction function for the magnetization error varies from sector to sector. For this reason, a correct correction function cannot be applied if there is no information on which sector among the p sectors, so that the magnetization error cannot be corrected accurately. It is also possible to select an accurate correction function by separately providing a sensor such as a hall sensor in order to determine the sector position. However, if a separate sensor is provided, there is a problem that the cost increases.

  On the other hand, a method of generating a magnetic field distribution similar to that of a multipolar magnet by combining a dipole magnet magnetized in the direction of the rotation axis and a pair of comb-shaped magnetic yokes is disclosed in JP-A-7-103790. No. (Patent Document 2). In this method, one comb-teeth yoke is magnetized to the N pole, and the other comb tooth is magnetized to the S pole. Therefore, on the side surface of the two-pole magnet, a magnetic field distribution in which the N pole and the S pole are interchanged is obtained. The magnetic field profile is similar to a multipolar magnet. This method has an advantage that a high-precision magnetic field profile can be realized because the sector interval and the magnetic field profile in the sector are determined by the mechanical processing accuracy of the comb-shaped yoke.

JP 2011-002311 A JP-A-7-103790

  However, in a method of configuring a rotation angle measurement device that generates a magnetic field distribution similar to that of a multipolar magnet by combining a dipole magnet magnetized in the direction of the rotation axis and a pair of comb-like magnetic yokes, As will be described later, a new phenomenon has been found that the accuracy of the measured rotation angle is greatly degraded when the position of the magnetic sensor is slightly shifted in the axial direction.

  An object of the present invention is directed to a rotation angle measuring device having a configuration as described in Patent Document 2, and a rotation angle measuring device capable of absorbing deterioration in rotation angle measurement accuracy due to an installation error of a magnetic sensor installation position. Is to provide.

  A feature of the present invention is that a bypass magnetic path forming body is provided which is opposed to the N pole side yoke and the S pole side yoke and flows by bypassing the magnetic field lines from the N pole to the S pole generated by the magnet. This is where an unnecessary magnetic field is prevented from affecting the magnetic sensor by the action of the body.

  According to the present invention, the magnetic field component including the rotation angle information can be selectively detected by the magnetic sensor by bypassing the magnetic field component in the rotation axis direction by the bypass magnetic path forming body, and the installation position of the magnetic sensor can be attached. It is possible to reduce deterioration in the measurement accuracy of the rotation angle due to an error.

It is a block diagram for demonstrating the structure of a general rotation angle measuring device, and the generation condition of the magnetic field by a magnet. It is explanatory drawing for demonstrating the horizontal direction component and vertical direction component of the magnetic field shown in FIG. It is a block diagram for demonstrating the structure of the rotation angle measuring device which becomes one Example of this invention, and the flow of a magnetic field. In the rotation angle measuring device shown in FIG. 3, (a) is a top view seen from the Z-axis (axis) direction, and (b) is a cross-sectional view showing a cross section thereof. It is a characteristic view which shows the correlation of the magnetic field angle and rotation angle by the rotation angle measuring device which becomes one Example of this invention. It is a characteristic view which shows the relationship between the magnetic field distortion error in the rotation angle measuring device which becomes one Example of this invention, and the conventional rotation angle measuring device, and the deviation | shift amount of an installation position. It is a characteristic view which shows the relationship between the magnetic field intensity in the rotation angle measuring device which becomes one Example of this invention, and the conventional rotation angle measuring device, and the deviation | shift amount of an installation position. It is a block diagram for demonstrating the structure of the rotation angle measuring device which becomes the other Example (2nd Embodiment) of this invention. It is a block diagram for demonstrating the structure of the rotation angle measuring device which becomes the other Example (3rd Embodiment) of this invention. It is a block diagram for demonstrating the structure of the rotation angle measuring device which becomes the other Example (4th Embodiment) of this invention. It is a block diagram for demonstrating the structure of the rotation angle measuring device which becomes the other Example (5th Embodiment) of this invention. It is a block diagram for demonstrating the structure of the rotation angle measuring device which becomes the other Example (6th Embodiment) of this invention. It is a block diagram for demonstrating the structure of the rotation angle measuring device which becomes the other Example (modified example of 6th Embodiment) of this invention. It is a block diagram for demonstrating the structure of the rotation angle measuring device which becomes the other Example (7th Embodiment) of this invention. It is explanatory drawing for demonstrating the point which measures the relationship of the magnetic field by the arrangement position of the bypass magnetic path formation body and magnetic sensor in the Example shown in FIG. It is a characteristic view which shows the relationship of the magnetic field by the arrangement position of the bypass magnetic path formation body shown in FIG. 15, and a magnetic sensor. It is a block diagram for demonstrating the structure of the rotation angle measuring device which becomes the other Example (8th Embodiment) of this invention. It is a block diagram for demonstrating the structure of the rotation angle measuring device which becomes the other Example (9th Embodiment) of this invention. It is a block diagram for demonstrating the structure which assembled | attached the rotation angle measuring device which becomes this invention to the electric motor. It is a block diagram for demonstrating the modification of the rotation angle measuring device assembled | attached to the electric motor shown in FIG. It is a block diagram for demonstrating the structure which assembled | attached the rotation angle measuring device which becomes this invention to the torque measuring device. It is a block diagram which shows the structure which applied the rotation angle measuring device which becomes this invention to the electric power steering apparatus of a motor vehicle. It is a block diagram for demonstrating the structure which assembled | attached the rotation angle measuring device which becomes this invention to the electric vehicle drive device. The structure of the rotation angle measuring apparatus generally known is shown, (a) is an overall block diagram, and (b) is an exploded view thereof. It is explanatory drawing which shows the magnetization state of the yoke protrusion of the magnetic flux generator which comprises the rotation angle measuring device shown in FIG. FIG. 25 is a characteristic diagram showing a correlation between a magnetic field angle and a rotation angle depending on a mounting position of a magnetic sensor of the rotation angle measuring device shown in FIG. It is a figure which shows the cross-sectional shape of the structural example of a bypass magnetic path formation body. It is a figure which shows the example of arrangement | positioning relationship between a bypass magnetic path formation body and a magnetic flux generator. It is a figure explaining the bypass magnetic path inclusion space of a bypass magnetic path formation body.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but a plurality of embodiments are proposed in the present invention. Accordingly, components having the same reference numbers represent the same components or components having similar functions.

  First, the problem found by the inventors that the measurement error increases when the sensor position is shifted will be described with reference to the drawings. Subsequently, the mechanism found by the inventors to increase the error will be described with reference to the drawings.

  FIG. 24 shows the configuration of the rotation angle measuring device 80. In FIG. 24A, the magnetic flux generator 202 has an annular magnet 211 and two annular yokes 215A and 215B. The magnetic flux generator 202 is fixed to the rotating shaft 121. The rotation center line 226 of the rotation shaft 121 is the Z axis. The midpoint position of the magnet 211 in the thickness direction is defined as Z = 0 mm (reference point).

  The magnet 211 is a two-pole magnetized magnet that is magnetized in the direction along the rotation axis 121 as shown in FIG. The yoke 215A and the yoke 215B are magnetic bodies having a comb-like shape. As shown in FIG. 24B, the magnetic flux generator 202 is configured by covering the yokes 215A and 215B from above and below the magnet 211, respectively. When the magnetization direction of the magnet 211 is N pole on the upper side and S pole on the lower side, the upper yoke 215A is magnetized to N pole, and the lower yoke 215b is magnetized to S pole. Therefore, when viewed from the side of the magnetic flux generator 202, the yoke protrusions 216A magnetized to the N pole and the yoke protrusions 216B magnetized to the S pole are alternately arranged. For this reason, the horizontal direction component (XY in-plane component orthogonal to the Z direction) of the magnetic field at the side surface position of the magnetic flux generator 202 has a magnetic field distribution similar to that of a multipolar magnetized magnet.

  Specifically, assuming that the number of yoke protrusions 216A formed on one yoke 215A is Np, the horizontal component of the magnetic field rotates Np times when the magnetic flux generator 202 rotates once. That is, it has Np sectors. This corresponds to a multipolar magnet magnetized with (Np × 2) poles.

  FIG. 25 illustrates the magnetization state of each of the yoke protrusions 216A and 216b when Np = 8. FIG. 25 is a cross-sectional view of the yoke protrusion 216 as viewed from the direction of the Z axis (rotation center line 226). The annular portion of the yoke 215A, the magnet 211, etc. are not shown. In FIG. 25, it can be seen that when the magnetic sensor is arranged on the X-axis and the magnetic flux generator 202 is rotated once, the horizontal component of the magnetic field is rotated only eight times at the position where the magnetic sensor 70 is arranged.

  The magnetic field calculation by the finite element method was performed, and the direction of the horizontal (in the XY plane) magnetic field at the location of the magnetic sensor 70 when the magnetic flux generator 202 rotated was quantitatively determined. The result is shown in FIG. 26, and the solid line shows the calculation result when Z = 0 mm (reference point) where the magnetic sensor position is the midpoint position in the magnet thickness direction.

  In FIG. 26, the horizontal axis represents the rotation angle (mechanical angle) of the magnetic flux generator 202, and the vertical axis represents the magnetic field angle (magnetic field angle) at the magnetic sensor position. When the magnetic flux generator 202 is rotated in the range of 0 to 180 °, the magnetic field angle rotates 4 times in the range of 0 to 360 ° with a period of 45 ° of rotation angle (mechanical angle). That is, one sector has a period of 45 ° and four sectors in a rotation range of 0 to 180 °. Since the range of 180 to 360 ° is the same, it can be seen that there is a rotation of the magnetic field angle of 8 sectors by one rotation of the magnetic flux generator 202.

  Consider a magnetic field angle distribution within one sector of a rotation angle (mechanical angle) of 0 to 45 °. Here, the “magnetic field angle distribution” indicates a correlation between the rotation angle (mechanical angle) of the magnetic flux generator and the magnetic field angle (magnetic field angle) at the magnetic sensor position.

  The ideal magnetic field angle distribution is such that the magnetic field angle varies linearly in the range of 0 to 360 ° within one sector. That is, as shown by the broken line in FIG. 26, a straight line connecting the magnetic field angle 0 ° and the magnetic field angle 360 ° between the rotation angle 0 ° and the rotation angle 45 ° is an ideal straight line. The same applies to a rotation angle of 45 ° to a rotation angle of 180 °.

  FIG. 26 shows that when Z = 0 mm, it is indicated by a solid line, but is slightly deviated from the ideal straight line. This deviation from the ideal straight line is the magnetic field distribution error. Here, the deviation from the ideal straight line is defined as “magnetic field distortion error”. As described above, the magnetic field distortion error includes a systematic error and an individual error. In FIG. 26, the magnetic field distortion error is in the range of ± 20 °. The deviation of ± 20 ° is as large as the magnetic field distortion error in the multipolar magnetized magnet, and can be corrected by an appropriate correction method.

  Next, the magnetic field angle in the case where the magnetic sensor 70 is arranged at a position of Z = −0.5 mm on the Z axis was examined. The results are shown in FIG. The magnetic field angle changes in a range of about ± 60 ° centering on 180 °, and is greatly deviated from the ideal straight line. Deviation from the ideal straight line (magnetic field distortion error) may reach a maximum of 180 ° and is an error amount that is difficult to correct.

  That is, the rotation angle of the magnetic flux generator 202 cannot be accurately measured from the measured value of the magnetic field angle only by shifting the installation position of the magnetic sensor 70 by 0.5 mm in the axial direction from the reference point (Z = 0 mm). become.

  As described above, in the rotation angle measuring apparatus using the magnetic flux generator combining the comb-shaped yoke and the magnet, the measurement accuracy of the rotation angle is greatly deteriorated if the installation position of the magnetic sensor is slightly shifted. It comes to occur. In an application used for an actual rotating machine or the like, an installation error, that is, an installation error always occurs, so that a new problem arises that it is difficult to measure the rotational angle with high accuracy.

  As described above, in a rotation angle measurement device using a magnetic flux generator that combines a comb-shaped yoke and a magnet, if the installation position of the magnetic sensor is slightly shifted in the axial direction, the measurement accuracy of the rotation angle is greatly degraded. The phenomenon of doing comes to occur.

  The inventors diligently investigated and investigated the cause of a significant deterioration in the measurement accuracy of the rotation angle when the installation position of the magnetic sensor slightly shifted in the axial direction. As a result, it was clarified that the detection accuracy of the rotation angle was lowered depending on the installation position for the following reasons.

  FIG. 1 schematically shows a spatial distribution in the magnetic field direction in the XZ section of the rotation angle measuring device 80. Since the magnet 211 is a dipole magnet that is magnetized in the Z-axis direction (the direction of the central axis 226 of the rotation axis), it emits a magnetic force line 250 from the N pole toward the S pole. The arrows shown in the figure indicate the direction of the magnetic force lines 250. Due to the symmetry of the magnet 211, the direction of the lines of magnetic force 250 at the position of Z = 0 mm is substantially parallel to the vertical direction, that is, the Z-axis direction on the paper surface.

  Since the magnet 211 is rotationally symmetric with respect to the Z-axis direction, the spatial distribution of the magnetic field lines 250 is generally isotropic at any azimuth (radially viewed from the Z-axis direction, from N pole to S pole). (Hereinafter, this magnetic field is referred to as a global magnetic field or a global line of magnetic force). On the other hand, the XY in-plane component of the magnetic field by the yoke protrusions 216A and 216B is superimposed on this global magnetic field as a local modulation magnetic field used for detecting the rotation angle. The XY in-plane component of the local modulation magnetic field is information necessary for detecting the rotation angle, and the rotation angle is measured by detecting the change in the XY in-plane component by the magnetic sensor 70.

  FIG. 2 shows the magnetic field vector at the installation position of the magnetic sensor. The magnetic field B is considered by dividing it into an XY in-plane component (in-plane component) Bip and a Z direction component Bz. As will be shown later, under the conditions in FIG. 26, the magnitude | Bz | of the Z direction component is 6 times or more of the in-plane component | Bip |. However, if the magnetic sensor senses only the in-plane component, the direction of the in-plane component Bip is detected without being affected by the Z-direction component | Bz |. When Z = 0, the magnetic field lines (global magnetic field) generated directly from the magnet are oriented in the vertical direction when Z = 0, so that the in-plane component Bip is only the local modulation magnetic field due to the yoke protrusion. Therefore, the magnetic field angle has a shape corresponding to the rotation angle (mechanical angle) as shown by the solid line in FIG.

  On the other hand, consider a case where the axial position of the magnetic sensor 70 is shifted by Z = −0.5 mm. As can be seen from FIG. 1, at a place where Z = 0 mm (reference point), the global magnetic field lines 250 emitted from the magnet 211 have the horizontal component Bip as described above. For this reason, the magnetic sensor 70 also detects a component of global magnetic field lines having a horizontal component Bip. As described above, since the global magnetic field lines coming out of the magnet are generally isotropic, the horizontal component thereof is 180 ° regardless of the rotation angle. This is the reason why the magnetic field angle changes around 180 ° as shown by the dotted line in FIG.

  As described above, it has been elucidated that the detection accuracy is lowered depending on the installation position of the magnetic sensor due to the presence of the global magnetic field lines generated from the magnet.

  Based on such knowledge, the present invention provides a technique for suppressing as much as possible the adverse magnetic field lines generated by the magnet 211 caused by the installation position of the magnetic sensor 70.

  In the embodiment described below, a magnetic field direction measuring sensor (GMR sensor) constituted by a GMR element which is one of magnetoresistive elements is used as the magnetic sensor 70. However, the magnetic sensor targeted by the present invention is not limited to the GMR sensor, and may be of other types as long as it is a magnetic field direction measuring sensor.

  The magnetic field direction measurement sensor is a sensor that outputs a signal corresponding to the direction of the magnetic field. In addition to the GMR sensor, the magnetic field direction measurement sensor outputs an AMR sensor (Anisotropic Magneto-Resistance sensor) using an anisotropic magnetoresistive element or a signal corresponding to the magnetic field direction using a plurality of Hall elements. There are sensors configured in the above. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 3 shows the overall configuration of a rotation angle measuring device 80 according to an embodiment of the present invention. The rotation angle measuring device 80 includes a magnetic flux generator 202, a magnetic sensor 70, and a bypass magnetic path forming body 240. The magnetic flux generator 202 is fixed to the rotating shaft 121 that rotates along the rotation center line 226, and rotates in conjunction with the rotation of the rotating shaft 121. The rotation center line 226 is taken as the Z axis.

  The magnetic flux generator 202 includes a magnet 211 and two yokes 215A and 215B. The magnet 211 is magnetized into two poles of an N pole and an S pole along the direction of the rotation center line 226 in the same manner as that shown in FIG. The magnet 211 has an annular shape (ring shape) and rotates in conjunction with the rotation of the rotating shaft 121.

  The two yokes 215A and 215B have yoke protrusions 216A and 216B, respectively. The yoke protrusions 216A and 216B are also made of a magnetic material. The yoke protrusions 216 </ b> A and 216 </ b> B have a comb-like shape extending on the side surface of the magnet 211.

  For easy understanding of the distinction between the two yokes, the yoke 215A provided on the N pole side of the magnet 211 may be referred to as an N pole side yoke, and the yoke 215B provided on the S pole side may be referred to as an S pole side yoke. Similarly, the yoke protrusion 216A of the N pole side yoke 215A may be referred to as an N pole yoke protrusion, and the yoke protrusion 216B of the S pole side yoke 215B may be referred to as an S pole yoke protrusion.

  As shown in FIG. 3, the N pole yoke protrusions 216A and the S pole yoke protrusions 216B are arranged so as to alternately mesh with each other.

  The yoke 215A and the yoke 215B are made of a magnetic material. In the present specification, the magnetic material is a material having a magnetic susceptibility of 10 or more. A material with a high magnetic susceptibility has the property of easily passing magnetic flux. The yoke protrusions 216A and 216B are also made of a magnetic material.

  The yoke 215A only needs to cover a part of the upper surface of the magnet 211, and does not need to cover the entire upper surface. Moreover, although it is preferable that the magnet 211 and the yoke 215A have a contact portion, it is not always essential. The reason why the contact is preferable is that the magnetic reluctance is lowered by the contact, so that the magnetic flux is effectively supplied from the magnet 211 to the yoke 215A. The same applies to the yoke 215B.

  Here, the “comb-tooth shape” is not limited to a rectangular protrusion as shown in the drawing, but includes a triangular or semicircular protrusion. The yoke protrusions 216A magnetized in the N pole and the yoke protrusions 216B magnetized in the S pole may be arranged alternately, and the shape of the protrusions is not limited.

  The magnetic sensor 70 is arranged so that the plane whose normal is the rotation center line 226 and the magnetic sensing surface of the magnetic sensor 70 are parallel to each other. That is, the magnetic sensing surface of the magnetic sensor 70 is arranged in parallel with the XY plane. By arranging in this way, the magnetic sensor 70 can measure the magnetic field direction of the magnetic field component (in-plane magnetic field component) parallel to the XY plane.

  The bypass magnetic path forming body 240, which is a characteristic configuration of the present invention, is disposed at a predetermined gap g so as to face the yoke 215A (N pole side yoke) and the yoke 215B (S pole side yoke). Yes. More specifically, the bypass magnetic path forming body 240 is arranged at a predetermined interval g so as to face the side surface of the magnet 211 and the surfaces of the yoke protrusion 216A and the yoke protrusion 216B.

  The bypass magnetic path forming body 240 forms a magnetic flux path. The bypass magnetic path forming body 240 is also made of a material that allows magnetic flux to pass, and is made of a magnetic material such as a steel plate (iron), permalloy, or mu metal. The bypass magnetic path forming body 240 functions as a bypass magnetic path for eliminating or reducing the influence of the global magnetic field lines 250 from the N pole to the S pole of the magnet 211 on the magnetic sensor 70.

  As shown in FIG. 3, the global magnetic field lines 250 from the N pole of the magnet 211 flow toward the S pole of the magnet 211, but pass through the bypass magnetic path forming body 240 in the vicinity of the bypass magnetic path forming body 240. It behaves so as to flow toward the south pole of the magnet 211. Therefore, the global magnetic field lines 250 do not affect the internal space of the bypass magnetic path forming body 240, or the influence is greatly suppressed.

  As shown in FIG. 3, the bypass magnetic path forming body 240 has a first surface 240A that extends outward facing the yoke (N pole side yoke) 215A, and extends outward facing the yoke (S pole side yoke) 215B. And a second surface 240B. In the case of the configuration shown in FIG. 3, it has a third surface 240C of magnetic material that connects the first surface 240A and the second surface 240B. As will be described later, the bypass magnetic path forming body 240 of the present invention may have a configuration in which the first surface 240A and the second surface 240B are directly connected, and in that case, the bypass magnetic path forming body 240 does not have the third surface.

  As shown in FIG. 3, the cross section of the bypass magnetic path forming body 240 has a shape having an opening 240 </ b> D that opens toward the magnetic flux generator 202, and exhibits, for example, a “U” shape of katakana characters. The opening 240D has a role for the magnetic sensor 70 to detect a modulation magnetic field by introducing a local modulation magnetic field generated by the yoke protrusions 216A and 216B. Further, both side surfaces of the bypass magnetic path forming body 240 are also opened, and the bypass magnetic path forming body 240 has three sides with the first surface 240A as the upper surface, the second surface 240B as the lower surface, and the third surface 240C as the outer peripheral side surface. The other three sides are open.

  The bypass magnetic path forming body 240 does not necessarily have a “U” shape. As will be described later, the bypass magnetic path forming body 240 intersects the Z axis direction and the Z direction included in the magnetic flux in the Z axis direction or intersects at a predetermined angle. What is necessary is just to have the function to flow a magnetic flux component.

  For example, as shown in FIG. 27 (a), the first surface 240A and the second surface 240B may be directly connected. It has a cross-sectional shape with the Greek letter lambda (Λ) turned sideways. Further, as shown in FIG. 27 (b), the first surface 240A and the second surface 240B may be connected by a curved magnetic body (third surface). Although not shown, the first surface 240A and the second surface 240B may have a curved surface configuration.

  In any case, the first surface 240A is disposed to face the yoke (N pole side yoke) 215A, and the second surface 240B is disposed to face the yoke (S pole side yoke) 215B.

  Here, the “arrangement facing each other” is used in a broad sense that the one side is arranged facing each other, or the one side is arranged close to each other.

  If some examples of the configuration “facing each other” are given, the configurations shown in FIGS. 28A, 28B, and 28C may be mentioned. First, as shown in FIG. 28A, the thickness Dm of the magnetic flux generator 202 is defined as the length from end to end of the pair of yokes 215A, 215B. Further, the height Hb of the bypass magnetic path forming body 240 is defined as the height of the bypass magnetic path forming body 240 on the magnetic flux generator side (as shown in FIG. 28A). In the configuration of FIG. 28A, the thickness Dm (Z direction) of the magnetic flux generator 202 and the height Hb of the bypass magnetic path forming body 240 are substantially equal. In the configuration of FIG. 28B, Dm> Hb. In the configuration of FIG. 28C, Dm <Hb.

  In the configuration of FIG. 27, the configuration of FIG. 28, or the combination of the configurations illustrated in FIGS. 27 and 28, the global magnetic field lines 250 emerging from the north pole of the magnet 211 In the vicinity, it passes through the bypass magnetic path forming body 240 and goes to the S pole of the magnet 211. For this reason, the global magnetic force 250 does not affect the internal space (magnetic path inclusion space) of the bypass magnetic path forming body 240, or the influence is greatly suppressed.

  Next, the arrangement relationship between the bypass magnetic path forming body 240 and the magnetic sensor 70 will be described. As schematically shown in FIG. 3, the magnetic field lines 250 coming out of the N pole go to the S pole via the bypass magnetic path forming body 240. For this reason, the influence of the global magnetic field lines 250 is reduced in the space surrounded by the bypass magnetic path forming body 240 and in the vicinity thereof (hereinafter referred to as “bypass magnetic path action space”). Therefore, the local modulation magnetic field generated by the yoke protrusions 216A and 216B is detected by the magnetic sensor 70.

  In the present specification, the “bypass magnetic path working space” is defined as a space in which the strength of the global magnetic field lines 250 in the Z direction is sufficiently weakened by the magnetic field bypass effect of the bypass magnetic path forming body 240. Therefore, it is not necessary to cover all surfaces of this space with the bypass magnetic path forming body 240. It is only necessary that the influence of the global magnetic field lines 250 is weakened by installing the bypass magnetic path forming body 240 as compared with the case where the bypass magnetic path forming body 240 is not provided, and in practice, if the strength is reduced to 50%. Provide.

  In this specification, the “bypass magnetic path inclusion space” is defined as a space surrounded by the bypass magnetic path formation body 240 and is also referred to as an “internal space” of the bypass magnetic path formation body. The bypass magnetic path inclusion space does not need to be covered with the bypass magnetic path forming body 240 on all surfaces. For example, as shown in FIG. 3, the bypass magnetic path inclusion space is defined as follows for the U-shaped bypass magnetic path forming body 240.

  The bypass magnetic path inclusion space will be described in detail with reference to FIG. 29A is a perspective view of the bypass magnetic path forming body 240 of FIG. 3, and FIG. 29B is a top view thereof. In the bypass magnetic path forming body 240 of FIG. 29, three surfaces, that is, the first surface 240A, the second surface 240B, and the third surface 240C are made of a magnetic material. Further, as described above, the bypass magnetic path forming body has the opening 240D facing the magnetic flux generator 202. Here, a virtual surface connecting the first surface side portion 242A and the second surface side portion 242B is referred to as a side surface opening surface 240E. There is a side opening surface 240F on the opposite side of the side opening surface 240E. In FIG. 29A, a virtual side defining the side opening surface 240E is indicated by a dotted line. In the case of this bypass magnetic path formation body 240, the bypass magnetic path inclusion space is defined as a space surrounded by the following six surfaces: a first surface 240A, a second surface 240B, a third surface 240C, And it is six surfaces of opening part 240D and side opening surface 240E, 240F.

  As shown in FIG. 27A described above, for the bypass magnetic path forming body 240 having no third surface, a bypass magnetic path inclusion space is defined by five surfaces excluding the third surface. It is clear that the bypass magnetic path inclusion space is similarly defined for the bypass magnetic path forming body 240 having other shapes.

  Further, in this specification, the “bypass magnetic path surrounding space” is defined as a union space of the bypass magnetic path inclusion space and the space between the bypass magnetic path inclusion space and the magnetic flux generator 202. In other words, the bypass magnetic path surrounding space is a union space of the internal space of the bypass magnetic path forming body 240 and the space between the internal space and the magnetic flux generator 202.

  Here, the “union” or “union space” of the two spaces A and B has the same meaning as the union set, either one or both It means a space belonging to the space. In other words, the sum space of the space A and the space B is a space obtained by combining the space A and the space B.

  As will be described later, the effect of reducing the magnetic field in the Z direction by the bypass magnetic path forming body 240 also acts on the space around the “bypass magnetic path surrounding space”. Therefore, the “bypass magnetic path working space” includes the “bypass magnetic path surrounding space” and its peripheral part.

  Each definition described above will be described in more detail with reference to FIG. 4A is a view of the magnetic flux generator 202 and the bypass magnetic path forming body 240 as viewed from above, and FIG. 4B is a view showing a cross section on the XZ plane. In this embodiment, the bypass magnetic path forming body 240 has a U-shaped cross section as described above, and no magnetic material is provided on the side surface of the bypass magnetic path forming body 240 facing the yoke protrusions 216A and 216B. It has a configuration.

  The bypass magnetic path forming body 240 has a shape obtained by cutting a circular ring at a predetermined angle as seen from FIG. 4A when viewed from above, and the magnetic sensor 70 is disposed in this internal space. Yes.

  In FIG. 4, a region A is a region spatially surrounded by the bypass magnetic path formation body 240. Region A is referred to as “bypass magnetic path inclusion space”. The region A is also called an internal space of the bypass magnetic path forming body.

  Region B is a region between magnetic flux generator 202 and region A. What should be noted here is that the thickness of the first surface 240A and the second surface 240B of the bypass magnetic path forming body 240 and the outer peripheral side surface of the magnetic flux generator 202 are shown in the cross-sectional view of FIG. The space area D1 and the space area D2 between the two are not included in the area B. The “bypass magnetic path surrounding space” is defined as the union space of region A and region B. In other words, the bypass magnetic path surrounding space is a space in which the region A (bypass magnetic path inclusion space) and the region B are combined.

  In other words, the “bypass magnetic path surrounding space” is a bypass magnetic path inclusion space (region A) and a space (region B) between the opening 240D of the bypass magnetic path forming body and the magnetic flux generator 240 connected thereto. ). Or, in other words, the bypass magnetic path surrounding space is a sum space of the bypass magnetic path inclusion space (region A) and the region B.

  The reason why the “bypass magnetic path surrounding space” includes the region B is that when the magnetic field direction of the region B is examined by magnetic field analysis, the Z-direction component of the magnetic field is reduced due to the presence of the bypass magnetic path formation body 240. On the other hand, strong magnetic lines of force extending from the north pole to the south pole of the magnet 211 from the yokes 215A and 215B through the first and second surfaces pass through the areas D1 and D2, and the magnetic sensor 70 is passed through the areas D1 and D2. However, the local modulation magnetic field formed by the yoke protrusions 216A and 216B cannot be detected. Therefore, the regions D1 and D2 are not included in the “bypass magnetic path surrounding space”.

  Further, in the regions C1 and C2 adjacent to the opening surfaces on both side surfaces of the bypass magnetic path forming body 240, the presence of the bypass magnetic path forming body 240 reduces the Z-direction component of the magnetic field as described later. Included in “bypass magnetic path working space”.

  That is, the “bypass magnetic path effect space” is defined as a space obtained by combining the regions A, B, C1, and C2. In this embodiment, both side surfaces of the bypass magnetic path forming body 240 are open. However, if these both side surfaces are closed with a magnetic material, the region C1 and the region C2 are reduced in the Z-direction magnetic field. Since the effect does not act, the “bypass magnetic path working space” is a space in which the region A and the region B are added.

  As can be seen from these definitions, when the magnetic sensor 70 is arranged in the “bypass magnetic path action space”, the Z-direction component of the magnetic field due to the global magnetic field lines 250 is reduced, and thus the rotational angle measurement accuracy is improved. Can be obtained.

  FIG. 5 shows the result of calculating the magnetic field angle at the arrangement position of the magnetic sensor 70 by the magnetic field calculation in the rotation angle measuring device 80 having the configuration shown in FIGS. 3 and 4. FIG. 5 corresponds to FIG. 26, calculates the magnetic field by the finite element method, and quantitatively determines the direction of the horizontal (XY plane) magnetic field at the location of the magnetic sensor 70 when the magnetic flux generator 202 rotates. Asked.

  The magnetic field angle when the magnetic sensor is installed at the position of Z = 0 mm (reference point) is shown by a solid line in FIG. When the magnetic sensor 70 is installed at the reference point Z = 0 mm, the magnetic field angle distribution is almost the same as the solid line in FIG. Deviation from the ideal ideal straight line (magnetic field distortion error) is about ± 30 °, which is substantially the same characteristic as in the case of FIG. 26 (configuration without the bypass magnetic path forming body 240).

  On the other hand, in FIG. 5, the dotted line marked with ● represents the case where the magnetic sensor 70 is installed at the position of Z = −0.5 mm. In the case of FIG. 5 (a configuration in which the bypass magnetic path forming body 240 is installed), substantially the same magnetic field angle distribution as that obtained when Z = 0 mm is set is obtained, and the error is about ± 30 °.

  Thus, even if the installation position of the magnetic sensor 70 is shifted by 0.5 mm in the axial direction, substantially the same characteristics are obtained, and the tolerance of the installation position is greatly improved as compared with the configuration without the bypass magnetic path forming body 240. You can see that

  As described above, the error of ± 30 ° is the same level as the magnetic field distortion of the multipolar magnet, and can be corrected by an appropriate correction method. For this reason, it is possible to measure the rotation angle with high accuracy.

  FIG. 6 is a plot of the relationship between the installation position of the magnetic sensor 70 and the magnetic field distortion error. Although the magnitude of the magnetic field distortion error differs depending on the rotation angle, the maximum value of the magnetic field distortion error is plotted on the vertical axis of FIG. The horizontal axis represents the deviation (mm) from the magnetic sensor installation position Z = 0 mm (reference point).

  In FIG. 6, a circle indicates a magnetic field distortion error in a conventional configuration without the bypass magnetic path forming body 240. When the installation position of the magnetic sensor 70 is shifted by 0.4 mm in the axial direction from Z = 0 mm (reference point), the error reaches 90 °, and when it is shifted by 0.5 mm in the axial direction, the error reaches 180 °. In this manner, the magnetic field distortion error increases dramatically as the axial displacement increases.

  On the other hand, the mark ● indicates the magnetic field distortion error in the present example in which the bypass magnetic path forming body 240 is provided. In this case, it can be seen that the magnetic field distortion error hardly increases even if the installation position of the magnetic sensor 70 is shifted by 0.5 mm in the axial direction. Thus, it can be seen that the tolerance of the installation position of the magnetic sensor 70 can be greatly improved by providing the bypass magnetic path forming body 240 as in the present embodiment.

  Next, it will be described that the Z-direction component of the magnetic field is reduced by providing the bypass magnetic path forming body 240. FIG. 7 is a graph showing the magnetic field intensity at the installation position of the magnetic sensor 70. In FIG. 7, as shown in FIG. 2, the magnetic field B is decomposed into the absolute value | Bip | of the magnetic field intensity of the XY in-plane component and the absolute value | Bz | Since the XY in-plane component | Bip | differs depending on the rotation angle of the magnetic flux generator 202, the minimum magnetic field strength is plotted. The horizontal axis in FIG. 7 indicates the installation position of the magnetic sensor 70, and is the amount of deviation (mm) from Z = 0 mm (reference point).

  First, looking at the result when the bypass magnetic path forming body 240 is not provided, at Z = 0 mm (reference point), the XY in-plane component | Bip | (plotted with a circle) is 20 mT, whereas in the Z direction The component | Bz | (plotted by Δ mark) is about 120 mT, and it can be seen that the Z-direction component is 6 times stronger. This is the intensity of the XY in-plane component and the Z-direction component of the magnetic field B at the reference point that is the basis for comparison.

  On the other hand, when the installation position of the magnetic sensor 70 is shifted by 0.4 mm in the axial direction, the XY in-plane component (plotted by a circle) is reduced to 3 mT, and the Z-direction component (plotted by a triangle) is 113 mT, which is the Z direction. The ingredient is 38 times stronger.

  As described above, the Z direction component is due to the globally distributed magnetic force lines 250 generated by the magnet 211, and has almost no magnetic field change component corresponding to the rotation angle. Thus, since the magnetic field of the XY in-plane component having the rotation angle information is small, the rotation angle measurement error becomes large. Furthermore, another problem is that when the axial displacement amount Z = 0.4 mm, the XY in-plane component (plotted with a circle) becomes smaller than when Z = 0 mm (reference point). When the measurement accuracy of the magnetic sensor 70 is normally 10 mT or less, the measurement accuracy deteriorates. Therefore, it can be understood from this point that the measurement accuracy of the rotation angle is deteriorated in the conventional configuration.

  Next, looking at the result when the bypass magnetic path forming body 240 according to the present example is provided, the component in the XY plane (plotted by ●) is 17 mT at Z = 0 mm (reference point), and the bypass It can be seen that the XY in-plane component (magnetic field strength) is substantially the same as in the conventional case where the magnetic path forming body 240 is not provided. This can be understood that the bypass magnetic path forming body 240 has substantially no adverse effect in the reference state.

  Furthermore, the Z-direction component of the magnetic field (plotted by ▲) is 8 mT, and the Z-direction component is greatly reduced compared to the case where the bypass magnetic path forming body 240 is not provided. In addition, the magnetic field strength of the XY in-plane component Is also getting smaller. Thus, since the XY in-plane component | Bip | including the rotation angle information is larger than the Z direction component | Bz |, the measurement accuracy of the rotation angle is improved.

  Further, in the case of the axial displacement Z = 0.4 mm, the XY in-plane component (plotted by ●) is 15 mT, and the Z-direction component (plotted by ▲) is 6.3 mT. As described above, even if the installation position of the magnetic sensor is slightly deviated, the XY in-plane component strength | Bip | of the magnetic field hardly decreases, and it can be understood that the rotation angle can be measured with high accuracy.

  Depending on the type of sensor used for the magnetic sensor 70, a strong Z-direction component of the magnetic field may adversely affect measurement accuracy. In this embodiment, a magnetic field direction measuring sensor is used as the magnetic sensor 70, and the magnetic field sensing surface is arranged perpendicular to the Z direction. Therefore, it is difficult to be influenced by the Z direction component of the magnetic field, but there are some that are affected by the type of sensor.

  Some magnetic field direction measuring sensors use Hall effect elements or magnetoresistive effect elements as magnetic field sensitive elements, but those using Hall effect elements are particularly susceptible to the Z-direction component of the magnetic field. For example, in a magnetic field direction measurement sensor that detects the magnetic field direction by measuring the spatial difference in magnetic field strength using a plurality of Hall effect elements, measurement is performed when the magnetic field component perpendicular to the sensor sensing surface is strong. Sensitive to accuracy.

  As described above, in the present embodiment, the influence of the global magnetic field or the magnetic field lines 250 is weakened by using the bypass magnetic path forming body 240. Therefore, particularly when the magnetic field direction measurement sensor using a plurality of Hall elements is used. The effect is great.

  Here, as a material of the bypass magnetic path forming body 240, basically, a magnetic body (magnetic susceptibility of 10 or more) capable of flowing a magnetic field line may be used, but a material having a magnetic susceptibility of 100 or more is practically used. It is desirable to use, specifically iron, silicon steel, permalloy, mu metal, and the like. In this example, plate-like iron was processed into the shape shown in FIGS. 3 and 4 to produce a bypass magnetic path forming body 240.

  As described above, the bypass magnetic path forming body 240 according to the present embodiment reduces or does not flow a magnetic field in the Z direction or a global magnetic field having a vector component in the Z direction and the horizontal direction to the magnetic sensor 70. In addition, since it works to bypass and flow through the bypass magnetic path forming body 240, the higher the magnetic susceptibility χ, the higher the effect. Examples of materials having a high magnetic susceptibility χ include iron (χ = 5000), silicon steel (χ = 7000), permalloy (χ = 40000 to 100,000), and mu metal (χ = 100000). In this example, since a sufficient effect was obtained using an iron plate having a thickness of 1 mm, iron that was inexpensive and easy to manufacture was used.

  Thus, in this embodiment, it is particularly preferable to use a magnetic material having a magnetic susceptibility χ of 100 or more. The reason for this is that if the bypass magnetic path forming body 240 is made of a material having a magnetic susceptibility χ of 100 or more, the magnetic flux becomes (χ + 1) times = 101 times or more that of air. This is because a magnetic field having vector components in the Z direction and the horizontal direction is effectively bypassed.

  Specifically, it is particularly preferable to use iron or silicon steel as the magnetic material. When a material having a magnetic susceptibility χ of more than 7000 such as permalloy or mu metal is used, the thickness of the bypass magnetic path forming body 240 is reduced. Is more preferable because the same effect can be obtained.

  Further, as a secondary effect of the present embodiment, it is difficult to be affected by a disturbance magnetic field. That is, it is conceivable that the measurement accuracy of the rotation angle deteriorates when a magnetic field from the outside enters the position of the magnetic sensor 70, but the magnetic sensor 70 is covered with the bypass magnetic path forming body 240 as in this embodiment. In addition, it can be expected that the disturbance magnetic field from the outside is shielded by the bypass magnetic path forming body and the measurement accuracy of the rotation angle can be suppressed from deteriorating.

  Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in that the yoke protrusions 216A and 216B of the magnetic flux generator 202 are formed in a triangular shape.

  In the first embodiment, the shapes of the yoke protrusions 216A and 216B are rectangular. However, if the yoke protrusions 216A and 216B are triangular as in the second embodiment, the XY in-plane component formed at the position of the magnetic sensor 70 is formed. There is an effect that the intensity of (magnetic field) is increased.

  The reason why the magnetic field intensity of the in-plane component is increased is that the triangular yoke protrusions 216A and 216B are compared to the opposing lengths of the rectangular yoke protrusions 216A and 216B when the distance between the yoke 215A and the yoke 215B is the same. It is considered that the strength of the XY in-plane component (magnetic field) is increased because the length of the opposite faces increases.

  That is, if the magnets 211 having the same strength are used, the use of the triangular yoke protrusions 216A and 216B has the effect that the magnetic field strength of the XY in-plane component formed at the installation position of the magnetic sensor 70 increases. Using triangular yoke protrusions 216A and 216B has the effect of improving measurement accuracy.

  In the first and second embodiments, the shape of the yoke protrusions 216A and 216B is disclosed as a rectangular shape and a triangular shape. However, the present invention is limited to these two shapes. is not.

  As schematically shown in FIG. 25, the magnetic flux generator 202 to which the present invention is applied has a configuration in which a yoke protrusion 216A magnetized in the N pole and a yoke protrusion 216B magnetized in the S pole are arranged adjacent to each other. . When such a configuration is used, the direction of the XY in-plane component | Bip | of the magnetic field at the position where the magnetic sensor 70 is arranged changes as the magnetic flux generator 202 rotates. Therefore, the rotation angle of the magnetic flux generator 202 can be measured by measuring the magnetic field angle.

  As described above, the shape of the yoke protrusions 216A and 216B is not limited as long as the magnetic flux generator 202 targeted by the present invention is configured such that the adjacent yoke protrusions 216A and 216B are alternately magnetized to the north and south poles. Is. Regardless of the shape, the global magnetic field lines 250 formed by the magnet 211 are formed in the Z direction, and the influence of the global magnetic field lines 250 is greatly reduced by the configuration in which the bypass magnetic path forming body 240 is provided. It can be done.

  Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment is different from the first embodiment in that the bypass magnetic path forming body 240 is not a shape obtained by cutting the circular ring at a predetermined angle as in the first embodiment, but is a rectangular shape when viewed from the upper surface.

FIG. 9 is a view of the rotation angle measuring device 80 as viewed from the Z-axis. In the third embodiment, the bypass magnetic path forming body 240 is a rectangular rectangle, and faces the magnetic flux generator 202 and is close to it. The side surface 240E has a linear shape.
With this configuration, the global magnetic field lines 250 formed by the magnet 211 are formed in the Z direction in the same manner as in the first and second embodiments. The influence of the magnetic field lines 250 can be greatly reduced. According to the third embodiment, when the bypass magnetic path forming body 240 is manufactured, the whole is a rectangular rectangle, and the bypass magnetic path forming body 240 is easily processed and manufactured.

  Next, a fourth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment, the bypass magnetic path forming body 240 is not a shape obtained by cutting the circular ring at a predetermined angle as in the first embodiment, but the shape viewed from the upper surface is a substantially rectangular shape, and is opposed to and close to the magnetic flux generator 202. This embodiment differs from the first embodiment in that the opposite side surface is formed in a concave shape.

  FIGS. 10A and 10B are views of the rotation angle measuring device 80 as viewed from the Z-axis. In the fourth embodiment, the bypass magnetic path forming body 240 is a substantially rectangular rectangle, and the magnetic flux Opposite side surfaces facing and close to the generator 202 have a concave contour. In FIG. 10A, the opposing side surface 240 </ b> F that faces and is close to the magnetic flux generator 202 has an arcuate contour that matches the shape of the side surface of the magnetic flux generator 202.

  10B, the opposing side surface 240G facing and adjacent to the magnetic flux generator 202 has a polygonal outline that matches the shape of the side surface of the magnetic flux generator 202. In this way, the distance (Air Gap length) between the magnetic flux generator 202 and the bypass magnetic path forming body 240 is shortened, so that the global magnetic field lines generated by the magnet 211 of the magnetic flux generator 202 are more effectively bypassed. There is an effect that it can flow to the magnetic path forming body 240.

  Next, a fifth embodiment of the present invention will be described with reference to FIG. In the fifth embodiment, a portion of the bypass magnetic path forming body 240 and a portion of the magnetic flux generator 202 are arranged so as to overlap each other with a gap in the axial direction of the rotation shaft. Is different. The bypass magnetic path forming body 240 uses the bypass magnetic path forming body 240 of Example 3 shown in FIG.

  FIG. 11A is a view of the rotation angle measuring device 80 as viewed from the Z axis, and FIG. 11B is a view showing an XZ cross section. The fifth embodiment is characterized in that the thickness of the portion of the bypass magnetic path forming body 240 facing the magnetic flux generator 202 in the “bypass magnetic path surrounding space” is larger than the thickness of the magnetic flux generator 202. .

  That is, as can be seen from the cross-sectional view of FIG. 11 (b), the first surface 240A of the bypass magnetic path forming body 240 is positioned above the yoke 215A of the magnetic flux generator 202 in the axial direction of the rotation axis. By configuring the two surfaces 240B to be positioned on the lower surface of the yoke 215B in the axial direction of the rotating shaft, the magnetic flux generator 202 and the bypass magnetic path forming body 240 are arranged so as to overlap each other.

  As a result, it is possible to effectively bypass the global magnetic field lines from the magnetic flux generator 202 to the bypass magnetic path forming body 240 while keeping the shape of the bypass magnetic path forming body 240 in an easily processable shape. In addition, since the magnetic flux generator 202 and the bypass magnetic path forming body 240 are arranged so as to overlap each other, the degree of the entry of the global magnetic field lines 205 from the Z-axis direction is smaller than in the first embodiment, and the measurement is further performed. The configuration can improve the accuracy.

  Here, the degree of overlap between the bypass magnetic path forming body 240 and the yokes 215A and 215B is such that at least the two corners of the bypass magnetic path forming body 240 extend to a position overlapping the outer peripheral edge of the yoke 215A and 215B. In the fifth embodiment, the both end corners of the bypass magnetic path forming body 240 are configured to extend beyond the outer peripheral edges of the yokes 215A and 215B.

  Next, a sixth embodiment of the present invention will be described with reference to FIG. In the sixth embodiment, a configuration of the bypass magnetic path forming body 240 is proposed. In the sixth embodiment, the bypass magnetic path forming body 240 uses the bypass magnetic path forming body 240 of the third embodiment shown in FIG. The bypass magnetic path forming body 240 is characterized by forming an opening 246 in the third surface 240C. With such a configuration, the magnetic sensor 70 can be easily installed.

  Specifically, the magnetic sensor 70 is introduced into the “bypass magnetic path surrounding space” of the bypass magnetic path forming body 240 through the opening 246, or conversely, the magnetic sensor 70 is moved from the opening 240 D on the opposite side of the opening 246 to “ Or can be introduced into a “bypass magnetic path enclosure space”. In this case, the opening 246 serves as a lead-out port for the signal wiring of the magnetic sensor 70. In this manner, the magnetic sensor 70 can be easily introduced by providing the opening 246, or can be used as a signal wiring outlet of the magnetic sensor 70.

  Here, since the bypass magnetic path formation body 240 is a magnetic body, reluctance (magnetic reluctance) is small, and magnetic flux is easy to pass compared with the air. Therefore, when a part of the bypass magnetic path forming body 240 is the opening 246, the magnetic flux in the bypass magnetic path forming body 240 flows while avoiding the opening 246. Therefore, even if an opening is provided in a part of the bypass magnetic path forming body 240, the effect of bypassing the magnetic flux can be obtained.

  Although FIG. 12 shows an example in which the opening 246 is provided in one of the constituent surfaces of the bypass magnetic path forming body 240, here, the third surface 240C, the openings 246 may be provided in a plurality of constituent surfaces.

  A modification of the sixth embodiment is shown in FIG. 13, and in this modification, an opening 246 is formed on the second surface 240 </ b> B (lower surface) of the bypass magnetic path forming body 240. In this modification, the magnetic sensor 70 is inserted from the opening 240D of the bypass magnetic path forming body 240 and installed in the “bypass magnetic path surrounding space” or “bypass magnetic path enclosing space”. It is pulled out from the opening 246 which becomes.

  When the signal line 208 is provided on the second surface 240B (lower surface) of the bypass magnetic path forming body 240 in this way, for example, the third surface 240C of the bypass magnetic path forming body 240 may not be provided with a lead opening, or the rotation angle. This is an effective configuration when the place where the measuring device is attached is restricted, for example, when a lead wire needs to be drawn out in the axial direction when it is provided in an electric motor as shown in FIG.

  In addition, although the above-mentioned various bypass magnetic path formation bodies 240 are exposed magnetic bodies, it is more desirable to cover the whole with synthetic resin using a technique such as insert molding. In this case, the magnetic sensor 70 is also surrounded by a synthetic resin in a liquid-tight manner, and is installed at a connection portion between the “bypass magnetic path inclusion space” or “bypass magnetic path inclusion space” of the bypass magnetic path forming body and the region B shown in FIG. However, it is necessary to firmly fix the bypass magnetic path forming body 240. In addition, it is important that the magnetic sensor 70 and the bypass magnetic path forming body 240 are integrally manufactured so that the dimensional relationship can be accurately obtained. For this reason, if both are managed as one, it will become a more desirable composition.

Next, a seventh embodiment of the present invention will be described with reference to FIG. The seventh embodiment is different from the first embodiment in that the bypass magnetic path forming body 240 is divided with the installation position of the magnetic sensor 70 as a boundary.

  A space between the divided two bypass magnetic path forming bodies 240-1 and 240-2 is defined as “magnetic path separation space”, and a distance between the two bypass magnetic paths is defined as “magnetic path separation length”. Define. Further, the expected angle when the magnetic path separation length is viewed from the rotation center line 226 is defined as “magnetic path separation angle”. In other words, the “magnetic path separation angle” is an angle formed by two straight lines formed by connecting the rotation center line 226 and both ends of the “magnetic path separation space”.

  In the seventh embodiment, the magnetic path separation space is formed substantially along the Z direction (axial direction), and each of the divided bypass magnetic path forming bodies 240-1 and 240-2 is the N pole of the magnet 211. Is divided so as to form a magnetic path connected to the S pole.

  In contrast to the seventh embodiment, if the magnetic path connected from the N pole to the S pole is divided, the reluctance (magnetic resistance) of the magnetic path, that is, the difficulty of passing the magnetic flux increases. Thus, the function of bypassing unnecessary magnetic fluxes from to the south pole will not be performed. In Example 7, since the magnetic path from the N pole to the S pole is maintained, the effect of bypassing the magnetic flux is maintained.

  As described above, the “magnetic path separation space” may be substantially along the Z direction (axial direction), and may be formed in a slightly oblique direction with respect to the Z direction. However, the degree of inclination should be determined within an allowable range according to the specifications for which the system is built.

  The “magnetic path separation space” defined in the seventh embodiment is included in the definition of the “bypass magnetic path action space” described above. This is because the Z-direction component of the magnetic field is sufficiently reduced by the action of the magnetic path magnetic path forming bodies 240-1 and 240-2. For this reason, when the magnetic sensor 70 is arranged in the “magnetic path separation space”, the effects of the present invention, that is, the tolerance of the installation position of the magnetic sensor 70 can be increased and the measurement accuracy can be improved.

  Next, the magnetic flux bypass effect when the magnetic path is separated by the “magnetic path separation space” in the seventh embodiment will be described. As described above, an object of the present invention is to reduce a magnetic field component in the Z direction that does not include rotation angle information. Therefore, the degree of effect can be known by examining the magnitude | Bz | of the Z direction component of the magnetic field at the position where the magnetic sensor 70 is installed. That is, it is understood that the effect is obtained as the magnitude | Bz | of the Z direction component of the magnetic field at the position where the magnetic sensor 70 is installed is smaller.

  Therefore, as shown in FIG. 15, in the configuration in which the bypass magnetic path forming bodies 240-1 and 240-2 are arranged, the magnitude | Bz | of the Z direction component at the measurement position P (α) on the dotted line is obtained by magnetic field calculation. It was. The measurement position P (α) is a place away from the X axis by an angle α. This time, the magnitude | Bz | of the Z direction component when the angle α is swung from −30 ° to + 30 ° with respect to the X axis. The magnetic field was calculated. Further, since the two bypass magnetic path forming bodies 240-1 and 240-2 are arranged apart from each other by the magnetic path separation angle β, the magnetic path separation angle β is set to 5 °, 10 °, 20 °, and 30 °. In each case, magnetic field calculation was performed.

  FIG. 16 shows the value of the magnitude | Bz | of the Z direction component at each measurement position measurement position P (α). As can be seen from FIG. 16, even when the magnetic path separation angle β is set to 5 °, 10 °, 20 °, and 30 °, in the space surrounded by the bypass magnetic path forming bodies 240-1 and 240-2. The magnitude | Bz | of the Z direction component is about 10 mT.

  In the configuration where the magnetic path separation angle β = 5 °, the magnitude | Bz | of the Z direction component is at a low level that is almost the same as that in the internal space of the bypass magnetic path forming bodies 240-1 and 240-2. It can also be seen that the magnitude | Bz | of the Z direction component is sufficiently small even at the magnetic path separation angle β = 10 °. On the other hand, as the magnetic path separation angle β increases, the magnitude | Bz | of the Z direction component increases. When the magnetic path separation angle β = 30 °, the measurement position P (α) = 0 (on the X axis) ) Is 80 mT, which is about the same level as the strength of about 100 mT in the absence of the bypass magnetic path forming bodies 240-1, 240-2 (240), and it can be seen that the effect is remarkably reduced.

  Thus, as can be seen from the results of FIG. 16, even when the bypass magnetic path forming body 240 is divided into two parts such as the bypass magnetic path forming bodies 240-1 and 240-2, the “magnetic path separation space” It can be understood that there is a magnetic flux reduction effect by the bypass magnetic path forming bodies 240-1 and 240-2. Further, as can be seen from FIG. 16, when the magnetic path separation angle β is set to 10 degrees or less, a higher effect can be obtained, and a more preferable result can be obtained.

  The effect of the configuration of the seventh embodiment has an effect that it is easy to install the magnetic sensor 70 in addition to the common effect that the installation tolerance of the magnetic sensor 70 is improved and the measurement accuracy of the rotation angle is improved.

  This effect is because the magnetic sensor 70 may be installed in the magnetic path separation space, so that the magnetic sensor 70 is installed inside the bypass magnetic path forming bodies 240-1 and 240-2, or the signal wiring of the magnetic sensor 70 is pulled out. This is because it becomes easier.

  Next, an eighth embodiment of the present invention will be described with reference to FIG. The eighth embodiment is different from the first embodiment in that a plurality of magnetic sensors 70, two here, are installed. In the eighth embodiment, the reliability of the rotation angle measuring device 80 can be improved by adopting a redundant system configuration with two magnetic sensors 70-1 and 70-2. This reliability is not the reliability related to the measurement accuracy possessed by the magnetic sensor 70 itself, but means the reliability with respect to failures and abnormalities.

  In the conventional installation method, since the tolerance of the installation position of the magnetic sensor 70 was narrow, basically, the magnetic sensor 70 was allowed to be installed only at a position of Z = 0 mm (reference position). For this reason, a configuration that takes into account a redundant system such as the use of two magnetic sensors 70 cannot be adopted, and even if it is adopted, the axial installation position shifts due to the influence of the thickness of the printed circuit board, for example. The accuracy was getting worse. The reason why the measurement accuracy is deteriorated is as described above.

  On the other hand, since the tolerance of the installation position of the magnetic sensor 70 is greatly increased by the configuration in which the bypass magnetic path forming body 240 is provided as described above, the configuration shown in FIG. 17 can be adopted. became. In FIG. 17, the magnetic sensors 70-1 and 70-2 are installed on both sides of the printed circuit board 161 with a space therebetween. In this embodiment, the magnetic sensors 70-1 and 70-2 are bonded to the printed circuit board 161. It is fixed by the method. As shown in the characteristic diagram of FIG. 6, by providing the bypass magnetic path forming body 240, the rotation angle can be accurately measured even when Z = 0.5 mm. Therefore, for example, even if the magnetic sensors 70-1 and 70-2 are installed on both sides of the printed board 161 having a thickness of 1 mm, the magnetic sensors 70-1 and 70-2 are set to Z = 0 mm (reference point). On the other hand, since it is located with a deviation of Z = ± 0.5 mm, sufficient measurement accuracy can be obtained.

  In this way, by using a redundant configuration using a plurality (two in this case) of the magnetic sensors 70, it is possible to detect a fault or failure of the magnetic sensor 70. In addition, when an abnormality or failure occurs in one of the magnetic sensors 70, it is possible to continue outputting correct rotation angle information by switching to a backup operation using a signal of a normally operating magnetic sensor. The effect can be expected.

  Next, a ninth embodiment of the present invention will be described with reference to FIG. The ninth embodiment is different from the first embodiment in that a magnetic flux generator 202 having triangular yoke protrusions 216A and 216B and two magnetic sensors 70-1 and 70-2 are used.

  In the ninth embodiment, the configuration of the redundant system shown in the eighth embodiment can be adopted. However, in the ninth embodiment, another function and effect described below is made by using the characteristics of the triangular yoke protrusions 216A and 216B. Can be obtained.

  Use of the triangular yoke protrusions 216A and 216B as shown in FIG. 18 has an advantage that the magnetic flux can be taken out efficiently. However, when the magnetic field measurement position, which is the installation position of the magnetic sensor 70, deviates from Z = 0 mm (reference point), the magnetic field angle distribution changes as described with reference to FIG.

  In the ninth embodiment, when the installation positions of the first magnetic sensor 70-1 and the second magnetic sensor 70-2 are respectively set to the predetermined lengths + Z1 and -Z1 from Z = 0 mm (reference point), the printed circuit board 161 is installed. When the position deviates by Δd from Z = 0 mm (reference point) to + Z1 side, the positions of the first magnetic sensor 70-1 and the second magnetic sensor 70-2 are (Z1 + Δd) from Z = 0 mm (reference point), respectively. , (−Z + Δd).

  Therefore, the position of the first magnetic sensor 70-1 changes in a direction away from Z = 0 mm (reference point), and the position of the second magnetic sensor 70-2 changes in a direction closer to Z = 0 mm (reference point). become. Therefore, when the average value of both the generated phase of the magnetic field angle of the first magnetic sensor 70-1 and the generated phase of the magnetic field angle of the second magnetic sensor 70-2 is obtained, the influence of the variation Δd of the installation position of the printed circuit board 161 is obtained. Can be offset. In this case, the magnetic field angle output from each of the magnetic sensors 70-1 and 70-2 can be obtained by a control device having a separate calculation function.

  As described above, by combining the magnetic flux generator 202 having the triangular yoke protrusions 216A and 216B and the two magnetic sensors 70-1 and 70-2, the rotation hardly affected by the position fluctuation of the printed circuit board 161 is achieved. The angle measuring device 80 can be obtained.

  Next, as a further embodiment of the present invention, a rotating machine using the rotation angle measuring device 80 described above will be described with reference to the drawings. The term “rotary machine” here is not limited to an electric motor or a generator, but is a concept including a machine including a rotary element such as a rotary shaft.

  FIG. 19 shows a cross section of a rotating machine according to the tenth embodiment. The tenth embodiment is an electric motor and includes an electric motor unit 100 and a rotation angle detection unit 200.

  The electric motor unit 100 generates rotational torque by rotating a plurality of rotating magnetic poles by a magnetic action of a plurality of fixed magnetic poles and a plurality of rotating magnetic poles, and includes a stator 110 and a plurality of stators constituting the plurality of fixed magnetic poles. It is comprised from the rotor 120 which comprises this rotating magnetic pole. The stator 110 includes a stator core 111 and a stator coil 112 attached to the stator core 111. The rotor 120 is disposed to face the inner peripheral side of the stator 110 via a gap and is rotatably supported. In the tenth embodiment, a three-phase AC permanent magnet synchronous motor is used as the motor.

The casing surrounding the electric motor main body is composed of a cylindrical frame 101 and a first bracket 102 and a second bracket 103 provided at both axial ends of the frame 101. Bearing 106 in the central portion in the first bracket 101, the center portion of the second bracket 103 is provided a bearing 107, respectively, these bearings 106 and 107 is rotatably supported by the rotation shaft 121 ing.

  A seal member (not shown) is provided between the frame 101 and the first bracket 102, and this seal member is an O-ring provided in an annular shape by the frame 101 and the first bracket 102 in the axial direction and the radial direction. It is sandwiched between and compressed. Thereby, between the flame | frame 101 and the 1st bracket 102 can be sealed fluid-tightly, and the front side can be waterproofed. Similarly, the frame 101 and the second bracket 103 are also waterproofed by a seal member (not shown).

  The stator 110 includes a stator core 111 and a stator coil 112 attached to the stator core 111, and is installed on the inner peripheral surface of the frame 101. The stator core 111 is a magnetic body (magnetic path forming body) formed by laminating a plurality of silicon steel plates in the axial direction. The stator core 111 protrudes inward in the radial direction from the annular back core and the inner peripheral portion of the back core. It is comprised from the several teeth arrange | positioned at equal intervals.

  A winding conductor constituting the stator coil 112 is intensively wound around each of the plurality of teeth. The plurality of winding conductors are electrically connected for each phase by a connecting member juxtaposed at the axial end of one coil end portion (on the second bracket 103 side) of the stator coil 112, and further as a three-phase winding. Electrically connected. Three-phase winding connection methods include a Δ (delta) connection method and a Y (star) connection method. In this embodiment, a Δ (delta) connection method is adopted.

  The rotor 120 includes a rotor core fixed on the outer peripheral surface of the rotating shaft 121 and a magnet (the rotor core and the magnet are not shown). In the surface magnet type permanent magnet motor, a plurality of magnets are arranged on the surface of the rotor core. In the embedded magnet type permanent magnet motor, the magnet is embedded in the rotor core.

  Next, the configuration of the rotation angle detection unit 200 will be described. The rotation angle detection unit 200 includes a magnetic sensor 70, a magnetic flux generator 202, and a bypass magnetic path forming body 240.

  The magnetic flux generator 202 rotates along the rotation center line 226 in conjunction with the rotation of the rotating shaft 121 of the rotating machine. In the configuration of FIG. 19, the magnetic flux generator 202 is attached to the rotating shaft 121 of the rotating machine. However, the present invention is not limited to this configuration, and the rotating shaft 121 of the rotating machine and the rotating shaft on which the magnetic flux generator 202 is installed are separate shafts, and both shafts are connected by gears or the like. May be rotated. Similarly, the rotation center line of the rotating shaft 121 of the rotating machine and the rotation center line of the magnetic flux generator may be made different from each other by changing the rotation direction using a gear or the like.

  The configuration of the magnetic flux generator 202 is the same as that shown in FIG. That is, it is composed of a dipole magnet 211 magnetized in the direction of the rotation center line 226 and the two yokes 215A and 215B. The yokes 215A and 215B have comb-shaped yoke protrusions 216A and 216B, respectively. In FIG. 19, the yokes 215A and 215B and the yoke protrusions 216A and 216B constituting the magnetic flux generator 202 are not shown.

  The bypass magnetic path forming body 240 is made of a magnetic material having a magnetic susceptibility of 10 or more. In this embodiment, a silicon steel plate having a thickness of 1 mm is used. The structure of the bypass magnetic path forming body 240 is the same as that shown in FIG. The bypass magnetic path forming body 240 was fixed to the second bracket 103 using the fixing tool 132.

  The magnetic sensor 70 is installed in the “bypass magnetic path working space” of the bypass magnetic path forming body 240, but more specifically, the magnetic sensor 70 is installed in the “bypass magnetic path surrounding space”. A magnetic field direction measuring sensor was used as the magnetic sensor 70, and the magnetic field sensing surface was arranged so as to be parallel to a plane having the rotation center line 226 as a normal line.

  Similar to that shown in FIG. 3, the rotation center line 226 is defined as the Z axis, and the origin of the Z axis is set to the midpoint of the magnetic flux generator 202 in the thickness direction. That is, it represents Z = 0 mm (reference point) described above, and is configured such that the magnetic sensor 70 is installed in accordance with this reference point. As a result, the magnetic sensor 70 detects the modulation magnetic field generated by the yoke protrusions 216A and 216B at a position where the measurement accuracy is best in terms of design. However, although it will be described repeatedly, it is actually difficult to install the magnetic sensor 70 at Z = 0 mm (reference point) as designed, and even if it is slightly shifted by 0.5 mm in the axial direction, the measurement accuracy is greatly reduced. . Therefore, the bypass magnetic path forming body 240 according to the present invention suppresses a decrease in measurement accuracy due to this deviation.

  With such a configuration, a local modulation magnetic field generated by the yoke protrusions 216 </ b> A and 216 </ b> B of the magnetic flux generator 202 can be detected, and the magnetic field angle linked to the rotation angle of the rotating shaft 121 can be measured by the magnetic sensor 70. It becomes like this.

  The reproducibility between the sectors of the magnetic field angle distribution (magnetic field angle profile) is governed by the mechanical accuracy of the yoke protrusions 216A and 216B, so that the reproducibility between the sectors is high. Therefore, the rotation angle of the rotation shaft 121 can be accurately measured from the measured magnetic field angle.

  The rotation angle signal measured in this way is input to a control device (electronic control unit). The control device can appropriately control the electric motor by outputting the drive voltage waveform of the electric motor using the information on the rotation angle.

  Note that it is a particularly preferable configuration because the number of poles of the motor matches the number of poles of the magnetic flux generator 202 (Np × 2) because the motor can be easily controlled. That is, when the number of poles of the motor is (p × 2), the number of yoke protrusions of the magnetic flux generator 202 may be determined so that (p × 2) = (Np × 2). The number of poles of the electric motor is equal to the number of poles of the rotating magnetic pole.

  Next, an eleventh embodiment of the present invention will be described with reference to FIG. The eleventh embodiment is different from the tenth embodiment in that a part of the bracket constituting the electric motor is used as a part of the constituent elements of the bypass magnetic path forming body 240.

  The eleventh embodiment is characterized in that some of the constituent elements of the electric motor are shared as constituent elements of the bypass magnetic path forming body 240. Specifically, the bypass magnetic path forming body 240 is installed in the second bracket 103 of the electric motor, but the second surface 240B of the bypass magnetic path forming body 240 shown in FIG. ing. If comprised in this way, the structure of the bypass magnetic path formation body 240 will be simplified, and there exists an effect which manufacture becomes easy from the ease of incorporating the magnetic sensor 70, etc. Since the second bracket 103 is usually made of an iron-based material, there is no problem because the magnetic material has a sufficient magnetic susceptibility.

  In addition, although it described that "the 2nd surface 240B is shared with the 2nd bracket 103", this description does not prescribe | regulate the magnetization direction of the magnet of the magnetic flux generator 202. It should be interpreted that either one of the first surface 240A and the second surface 240B is shared with a component of the casing of the rotating machine.

  As described above, in the eleventh embodiment, the second surface 240B of the bypass magnetic path forming body 240 is configured using the surface of the second bracket 103. In this configuration, since the magnetic field lines in the Z direction flow from one yoke to the other yoke through the bypass magnetic path forming body 240 and the second bracket 103, the magnetic field lines in the Z direction adversely affect the magnetic sensor 70. Can be suppressed. Note that if there is a gap in the contact surface between the bypass magnetic path forming body 240 and the second bracket 103, the magnetic reluctance increases and the effect of reducing the bypass of the magnetic field lines in the Z direction may decrease. The body 240 and the second bracket 103 need to be configured so as to be in close contact with each other. In the present embodiment, the two are closely adhered and fixed, but an increase in magnetic reluctance can be taken by bringing them into close contact via a soft resin or the like that allows magnetic flux to pass through.

  Next, a twelfth embodiment of the present invention will be described with reference to FIG. The twelfth embodiment shows the configuration of the torque measuring device (torque sensor).

  The torque measuring device according to the twelfth embodiment includes an input shaft 131 and an output shaft 132 connected by a torsion bar 135, and a rotation angle measuring device 80 installed on each of the input shaft 131 and the output shaft 132. is there.

  In the torque measuring device according to the twelfth embodiment, an input shaft 131 and an output shaft 132 are connected by a torsion bar 135. The rotation angle θ1 of the input shaft 131 and the rotation angle θ2 of the output shaft 132 are measured, and the torque M applied to the shaft is measured from the difference Δθ = θ2−θ1. Using the fact that the torque M is proportional to the angle difference Δθ, the torque M is measured from Δθ. Such a torque measuring device is used in a steering device or the like that transmits the movement of a steering wheel of an automobile to wheels.

  The input shaft 131 is provided with a first magnetic flux generator 202-1 and the output shaft 132 is provided with a second magnetic flux generator 202-2. The two magnetic flux generators 202-1 and 202-2 are each composed of a magnet 211 and two yokes 215A and 215B.

  Further, bypass magnetic path forming bodies 240-1, 240-2 and magnetic sensors 70-1, 70-2 are arranged on the respective side surfaces of the magnetic flux generators 202-1 and 202-2. The magnetic sensors 70-1 and 70-2 are disposed in the “bypass magnetic path action space” of the bypass magnetic path forming bodies 240-1 and 240-2, respectively. Magnetic sensors 70-1 and 70-2 are arranged in the “bypass magnetic path surrounding space” of the body 240. The bypass magnetic path forming bodies 240-1 and 240-2 are fixed to a mounting housing (not shown). The attachment housing may be a dedicated attachment of the bypass magnetic path forming body 240, or the bypass magnetic path forming body 240 may be attached to a component constituting another steering device.

  In the twelfth embodiment, since the magnetic sensors 70-1 and 70-2 are arranged in the “bypass magnetic path action space” of the bypass magnetic path forming body 240, the magnetic flux generators 202-1 and 202-2 are generated. Since the magnetic field component in the Z direction is bypassed by the bypass magnetic path forming body 240, the rotation angles θ1 and θ2 can be measured with high accuracy. The reason for this is as described above.

  In the torque measuring device, the angle difference Δθ is designed to be about 4 ° at the time of the maximum torque. Therefore, it is necessary to measure the angle difference of the rotation angle of −4 ° to + 4 ° with high accuracy.

  Therefore, in the twelfth embodiment, by increasing the number of yoke protrusions Np1 of the magnetic flux generator 202-1 and the number of yoke protrusions Np2 of the magnetic flux generator 202-2, a large change in magnetic field angle can be achieved even with a small change in rotation angle. Designed to be Specifically, when each of Np1 and Np2 is set to 10 or more, it becomes possible to measure an angular difference of a rotation angle of −4 ° to + 4 ° with high accuracy.

  Preferably, the angle difference can be easily calculated by designing the two magnetic flux generators 202-1 and 202-2 to have the same number of yoke protrusions 216A and 216B, that is, Np1 = Np2. That is, the correspondence between the change in the magnetic field angle and the change in the mechanical angle as shown in FIG. 5 is equal between the two rotation angle measuring devices 80, so that the calculation of the difference Δθ = θ2−θ1 between the rotation angles is simplified. effective.

  In the twelfth embodiment, when Np1 = Np2 = 18 is set, the rotation angle change amount corresponding to one rotation of the magnetic field angle is 360 ° / Np = 20 °. Therefore, the rotation angle change of ± 4 ° is approximately (± 4 × Np) = measured as a change in magnetic field angle of ± 80 °. In this way, the rotation angle difference Δθ can be measured with high accuracy. The torque M can be measured by multiplying the rotation angle difference Δθ by an appropriate proportional coefficient. Such calculation is executed by a control device having a separately provided arithmetic function.

  The torque measuring device may be provided with a rotation angle measuring unit as necessary. For example, when used in an electric power steering apparatus, it may be desired to measure the rotation angle of the input shaft 131 in addition to torque measurement. In the case of an electric power steering device, the rotation angle of the input shaft 131 corresponds to a steering angle corresponding to the angle of the steering wheel.

  In this case, the sensor magnet 143 and the magnetic sensor 142 as shown in FIG. 21 constitute a rotation angle measurement unit. The rotation angle measurement unit is not an essential component in the torque measurement device, but is required in the electric power steering device.

  The sensor magnet 143 is installed on the input shaft 131, and the sensor magnet 143 is a dipole magnet magnetized in the radial direction. A magnetic sensor 142 is disposed on the side surface of the sensor magnet 143. The magnetic sensor 142 is a magnetic field direction measurement sensor and is fixed to a housing (not shown). Since the sensor magnet 143 is a dipole magnet, the magnetic field angle measured by the magnetic sensor 142 corresponds to one rotation corresponding to one rotation of the input shaft. By appropriately correcting the magnetic field angle measured by the magnetic sensor 142, the rotation angle of the input shaft 131 can be measured.

  Next, a thirteenth embodiment of the present invention will be described with reference to FIG. 22. The thirteenth embodiment shows the configuration of an electric power-assisted steering system.

  In FIG. 22, a steering shaft 503 mechanically coupled to a handle 501 is connected to a coupling portion 504 via a torque sensor 502. A rotating shaft 121 of the electric motor 100 is connected to a connecting portion 504 constituted by a reduction gear or the like, and a connecting shaft 505 is further connected to the connecting portion 504.

  The connecting shaft 505 is connected to a gear box 506, and a tie rod 507 is connected to the gear box 506. The gear box 506 converts the rotational movement of the connecting shaft 505 into the linear movement of the tie rod 507, and tires (not shown) are arranged at both ends of the tie rod 507, and the tires according to the linear movement of the tie rods. The direction will be changed. Such an electric steering system has a well-known structure.

  The rotating body 121 is a rotating shaft of the electric motor 100, and a magnetic flux generator 202 is installed at one end. A magnetic sensor 70 and a bypass magnetic path forming body 240 are installed in the vicinity of the magnetic flux generator 202, and the rotation angle of the rotating body 121 is measured and the rotation angle information is transmitted to the ECU 411. The magnetic flux generator 202, the magnetic sensor 70, and the bypass magnetic path forming body 240 constitute a rotation angle measuring device 80. The configuration and operation of the rotation angle measuring device 80 are as described above.

  The configuration of the magnetic flux generator 202 is the same as that of the magnetic flux generator 202 shown in FIGS. 3 and 4, and is composed of yokes 215 </ b> A and 215 b having yoke protrusions 216 </ b> A and 216 b, and a magnet 211. Further, the bypass magnetic path forming body 240 is also configured as shown in FIGS.

  When the driver turns the handle 501, the rotational operation is detected by the torque sensor 502 and transmitted to the ECU 411 as an electrical signal. The ECU 411 calculates an appropriate motor drive amount from the signal from the torque sensor 502, the rotation angle signal θ from the rotation angle measuring device 80, the vehicle speed signal, and the like, and transmits the signal to the motor drive unit 412. Accordingly, the electric motor 100 rotationally drives the rotating body 121 to assist (assist) the rotation of the connecting shaft 505. In this way, the exercise of changing the direction of the tire is assisted.

  In the thirteenth embodiment, since the magnetic sensor 70 in the rotation angle measuring device 80 is disposed in the “bypass magnetic path action space” of the bypass magnetic path forming body 240, the magnetic field in the Z direction is bypassed with high accuracy. The rotation angle can be measured.

  Next, a fourteenth embodiment of the present invention will be described with reference to FIG. 23. The fourteenth embodiment shows the configuration of an electric vehicle drive device.

  In FIG. 23, the electric vehicle drive device for hybrid vehicles which combined the internal combustion engine and the electric motor as motive power of a motor vehicle is shown.

  The output rotation shaft of the internal combustion engine 553, the generator 552, and the drive motor 551 are arranged on the same axis, and each of them transmits power appropriately by the function of the power distribution mechanism 554. The method of power distribution is appropriately set based on information such as the running state of the vehicle, the acceleration state, and the battery charging state. Further, a power coupling mechanism 557 for transmitting power from the power distribution mechanism 554 to the power shaft 558 is provided.

  The motor described in FIG. 19 is used as the drive motor 551, and the drive motor 551 includes the motor unit 100 and the rotation angle detection unit 200 as described in FIG. The rotation angle measuring unit 200 includes a magnetic flux generator 202-1, a magnetic sensor 70-1, and a bypass magnetic path forming body 240-1.

  The configuration of the magnetic flux generator 202-1 is the same as that of the magnetic flux generator shown in FIGS. 3 and 4, and is composed of yokes 215 A and 215 B having yoke protrusions 216 A and 216 B and a magnet 211. Further, the bypass magnetic path forming body 240 is also configured as shown in FIGS.

  The generator 552 is also provided with a rotation angle detection unit, and this rotation angle measurement unit includes a magnetic flux generator 202-2, a magnetic sensor 70-2, and a bypass magnetic path formation body 240-2. The configuration is the same as that of the magnetic flux generator 202-1.

  In the electric vehicle driving apparatus having such a configuration, the magnetic sensor 70 in the rotation angle measuring device 8080 of the driving electric motor 551 and the generator 552 is disposed in the “bypass magnetic path working space” of the bypass magnetic path forming body 240. Therefore, the rotation angle can be measured with high accuracy by bypassing the magnetic field in the Z direction.

  The number Np1 of the magnetic poles of the yoke protrusions 216A and 216B of the magnetic flux generator 202-1 preferably corresponds to the number of magnetic poles (p × 2) of the drive motor 551. For example, the number of magnetic poles of the drive motor is (p × 2). ), The number of magnetic poles of the yoke protrusions 216A and 216B is preferably Np = p. In this way, the magnetic field angle signals output from the magnetic sensors 70-1 and 70-2 have a cycle corresponding to the electrical angle of the drive motor 551, and thus the drive motor can be easily controlled. As a matter of course, the relationship between the number Np of magnetic poles of the yoke protrusions 216A and 216B of the magnetic flux generator 202-2 and the number of magnetic poles of the generator 552 is the same.

  In such an electric vehicle drive device, the number of poles of the electric motor may be increased in order to obtain a high output torque. According to the magnetic flux generator 202 used in the rotation measuring device described in the present invention, the yoke protrusions 216A and 216B are used. The number of poles of the magnetic flux generator can be easily increased by increasing the number of magnetic flux generators, which is suitable for use in such an electric vehicle drive device.

  DESCRIPTION OF SYMBOLS 70 ... Magnetic sensor, 80 ... Rotation angle measuring device, 100 ... Motor part, 110 ... Stator, 111 ... Stator core, 112 ... Stator coil, 120 ... Rotor, 121 ... Rotating shaft, 131 ... Input shaft, 132 ... Output shaft, 135 DESCRIPTION OF SYMBOLS ... Torsion bar 142 ... Magnetic sensor 143 ... Sensor magnet 200 ... Rotation angle detection part 202 ... Magnetic flux generator 211 ... Magnet 215 ... Yoke 216 ... Yoke protrusion 226 ... Rotation center line 240 ... Bypass magnet Path forming body, 240A: first surface of bypass magnetic path forming body, 240B: second surface of bypass magnetic path forming body, 240C: third surface of bypass magnetic path forming body, 240D: opening of bypass magnetic path forming body 246: opening, 250: magnetic field lines, 411: electronic control unit, 412: drive unit, 501: handle, 502 ... torque sensor 503 ... Steering shaft, 504 ... Connecting part, 505 ... Connecting shaft, 506 ... Gear box, 507 ... Tie rod, 551 ... Drive motor, 552 ... Generator, 553 ... Internal combustion engine, 554 ... Power distribution mechanism, 557 ... Power coupling mechanism 558 ... Power shaft.

Claims (25)

A rotation angle measuring device having a magnetic flux generator that can rotate along a rotation center line, and a magnetic sensor that outputs a signal according to a magnetic field direction,
The magnetic flux generator is provided on the N pole side yoke provided on the N pole side of the magnet and on the S pole side along the direction of the rotation center line. S pole side yoke
The north pole side yoke has a comb-like north pole yoke protrusion extending on the side surface of the magnet,
The S pole side yoke has comb-shaped S pole yoke protrusions extending on the side surfaces of the magnets, and the N pole yoke protrusions and the S pole yoke protrusions are arranged to alternately engage with each other.
The rotation angle measuring device has a bypass magnetic path forming body made of a magnetic material and disposed to face the north pole side yoke and the south pole side yoke,
The magnetic sensor is disposed in a bypass magnetic path action space formed by the bypass magnetic path forming body,
The magnetic sensor is a magnetic field direction measurement sensor that measures a magnetic field angle,
Wherein the magnetic field sensing face of the magnetic sensor is disposed in parallel to the plane having a normal line of the rotation center line,
The rotation angle measuring device, wherein the bypass magnetic path forming body reduces the influence of the magnetic lines of force on the magnetic sensor by bypassing and flowing the magnetic lines of force from the N pole to the S pole of the magnet . In the rotation angle measuring device according to claim 1,
The bypass magnetic path forming body has a first surface facing the north pole side yoke, a second surface facing the south pole side yoke, and an opening facing the magnetic flux generator,
The first surface and the second surface are connected directly or via a magnetic body,
The magnetic sensor is disposed in a bypass magnetic path inclusion space of the bypass magnetic path forming body and a space obtained by coupling a space between the opening and the magnetic flux generator. Angle measuring device. In the rotation angle measuring device according to claim 1 ,
A rotation angle measuring device comprising a plurality of bypass magnetic path forming bodies, wherein the magnetic sensor is arranged between the plurality of bypass magnetic path forming bodies. A rotation angle measuring device having a magnetic flux generator that can rotate along a rotation center line, and a magnetic sensor that outputs a signal according to a magnetic field direction,
The magnetic flux generator is provided on the N pole side yoke provided on the N pole side of the magnet and on the S pole side along the direction of the rotation center line. S pole side yoke
The north pole side yoke has a comb-like north pole yoke protrusion extending on the side surface of the magnet,
The S pole side yoke has comb-shaped S pole yoke protrusions extending on the side surfaces of the magnets, and the N pole yoke protrusions and the S pole yoke protrusions are arranged to alternately engage with each other.
The rotation angle measuring device has a bypass magnetic path forming body made of a magnetic material and disposed to face the north pole side yoke and the south pole side yoke,
The magnetic sensor is disposed in a bypass magnetic path surrounding space formed by the bypass magnetic path forming body,
The magnetic sensor is a magnetic field direction measurement sensor that measures a magnetic field angle,
Wherein the magnetic field sensing face of the magnetic sensor is arranged parallel to the plane having a normal line of the rotation center line,
The rotation angle measuring device, wherein the bypass magnetic path forming body reduces the influence of the magnetic lines of force on the magnetic sensor by bypassing and flowing the magnetic lines of force from the N pole to the S pole of the magnet . In the rotation angle measuring device according to claim 4,
The bypass magnetic path forming body has a first surface facing the north pole side yoke, a second surface facing the south pole side yoke, and an opening facing the magnetic flux generator,
The first surface and the second surface are connected directly or via a magnetic body,
The magnetic sensor is disposed in a bypass magnetic path inclusion space of the bypass magnetic path forming body and a space obtained by coupling a space between the opening and the magnetic flux generator. Angle measuring device. In the rotation angle measuring device according to any one of claims 1 to 5,
The bypass magnetic path forming body is made of a magnetic body, and its magnetic susceptibility is 100 or more. In the rotation angle measuring device according to claim 6,
The bypass magnetic path forming body is made of any one of iron, silicon steel, permalloy, and mu metal. In the rotation angle measuring device according to claim 2 or 5,
The first surface of the bypass magnetic path forming body facing the N pole side yoke and the side of the second surface facing the S pole side yoke are formed in a straight line. Rotation angle measuring device. In the rotation angle measuring device according to claim 2 or 5,
The first magnetic surface of the bypass magnetic path forming body facing the north pole side yoke and the side of the second surface facing the south pole side yoke are formed in a concave shape. Angle measuring device. In the rotation angle measuring device according to claim 1 or 4,
The bypass magnetic path forming body includes a first surface facing the N pole side yoke so as to be overlapped with a gap in the direction of the rotation center line, and a gap in the direction of the S pole side yoke and the rotation center line. And the first surface and the second surface are connected directly or via a magnetic body, and the magnetic sensor is the bypass magnetic path forming body. The rotation angle measuring device is disposed in a bypass magnetic path inclusion space. In the rotation angle measuring device according to claim 1 or 4,
The rotation angle measuring device according to claim 1, wherein the N pole side yoke protrusion and the S pole side yoke protrusion have a rectangular shape. In the rotation angle measuring device according to claim 1 or 4,
The rotation angle measuring device according to claim 1, wherein the N pole side yoke protrusion and the S pole side yoke protrusion have a triangular shape or an arc shape. In the rotation angle measuring device according to claim 1 or 4,
A rotation angle measuring device, wherein a plurality of the magnetic sensors are arranged in the direction of the rotation center line in a magnetic path surrounding space formed by the bypass magnetic path forming body. In the rotation angle measuring device according to claim 2 or 5,
The bypass magnetic path forming body is formed with an opening in which both side surfaces formed by the first surface, the second surface, and the magnetic body connecting the first surface and the second surface are opened. A rotation angle measuring device characterized by that. In the rotation angle measuring device according to claim 2 or 5,
The bypass magnetic path forming body includes an opening on at least one surface of the first surface, the second surface, or a magnetic body connecting the first surface and the second surface. Rotation angle measuring device. In the rotation angle measuring device according to claim 1 or 4,
The rotation angle measuring apparatus according to claim 1, wherein the magnetic sensor is composed of one of a magnetoresistive element and a Hall element. At least a rotor having a rotating magnetic pole fixed to a rotating shaft, a fixed magnetic pole surrounding the rotor, a frame containing the rotating magnetic pole and the fixed magnetic pole, and fixed to both ends of the frame and cooperating with the frame. A rotating machine comprising a bracket for housing the rotating magnetic pole and the fixed magnetic pole,
The rotating machine includes a rotation angle measuring device having a magnetic flux generator that can rotate along a rotation center line in conjunction with rotation of the rotating shaft, and a magnetic sensor that outputs a signal corresponding to the magnetic field direction.
The magnetic flux generator is provided on the N pole side yoke provided on the N pole side of the magnet and on the S pole side along the direction of the rotation center line. S pole side yoke
The north pole side yoke has a comb-like north pole yoke protrusion extending on the side surface of the magnet,
The S pole side yoke has comb-shaped S pole yoke protrusions extending on the side surfaces of the magnets, and the N pole yoke protrusions and the S pole yoke protrusions are arranged to alternately engage with each other.
The rotation angle measuring device has a bypass magnetic path forming body made of a magnetic material and disposed to face the north pole side yoke and the south pole side yoke,
The magnetic sensor is disposed in a bypass magnetic path surrounding space formed by the bypass magnetic path forming body,
The magnetic sensor is a magnetic field direction measurement sensor that measures a magnetic field angle,
Wherein the magnetic field sensing face of the magnetic sensor is arranged parallel to the plane having a normal line of the rotation center line,
The bypass machine reduces the influence of the magnetic lines of force on the magnetic sensor by bypassing and flowing the magnetic lines of force from the N pole to the S pole of the magnet . The rotating machine according to claim 17,
A rotating machine using the bracket as a part of the bypass magnetic path forming body. The rotating machine according to claim 17,
A rotary machine characterized in that p and Np are equal when the number of poles of the rotary machine is (2 × p) and the number of yoke protrusions of the yoke is Np. The rotating machine according to claim 17,
The rotating machine is used as an electric motor or a generator used in a vehicle drive device used in an automobile. An input shaft and an output shaft are connected by a torsion bar, and a rotary machine for torque measurement that measures torque according to a rotation angle between the input shaft and the output shaft,
The rotating machine includes a rotation angle measuring device including a magnetic flux generator that can rotate along a rotation center line of the input shaft or the output shaft, and a magnetic sensor that outputs a signal corresponding to a magnetic field direction.
The magnetic flux generator is provided on the N pole side yoke provided on the N pole side of the magnet and on the S pole side along the direction of the rotation center line. S pole side yoke
The north pole side yoke has a comb-like north pole yoke protrusion extending on the side surface of the magnet,
The S pole side yoke has comb-shaped S pole yoke protrusions extending on the side surfaces of the magnets, and the N pole yoke protrusions and the S pole yoke protrusions are arranged to alternately engage with each other.
The rotation angle measuring device has a bypass magnetic path forming body made of a magnetic material and disposed to face the north pole side yoke and the south pole side yoke,
The magnetic sensor is disposed in a bypass magnetic path surrounding space formed by the bypass magnetic path forming body,
The magnetic sensor is a magnetic field direction measurement sensor that measures a magnetic field angle,
Wherein the magnetic field sensing face of the magnetic sensor is arranged parallel to the plane having a normal line of the rotation center line,
The bypass machine reduces the influence of the magnetic lines of force on the magnetic sensor by bypassing and flowing the magnetic lines of force from the N pole to the S pole of the magnet . The rotating machine according to claim 21,
The number of the N pole side yoke protrusions and the S pole side yoke protrusions is 10 or more. The rotating machine according to claim 21,
The rotating machine is used for a torque sensor provided in an electric power steering apparatus.   A vehicle drive device using the rotary machine according to claim 17 as an electric motor.   An electric power steering apparatus using the rotating machine according to claim 21.

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