JP2008203183A - Magnetic core unit and torque sensor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To separate adjacent magnetic coils and to facilitate the assembly of constituent components in a magnetostrictive torque sensor. <P>SOLUTION: A measurement unit 200 of the torque sensor comprises a cylindrical magnetic head 210, an outer circumferential bobbin 211, and an inner circumferential bobbin 213. The magnetic head 210 comprises a cylindrical yoke joint 240 and annular first and second yoke parts 220a and 220b fitted into its opening. Two magnetic cores are constituted of soft magnetic parts 232a1, 232a2, 232b1, 232b2, 252a, 252b of the yoke connection part 240 and the first and second yoke parts 220a and 220b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic core unit used in a torque sensor that detects the axial torque of a rotating shaft in a non-contact manner using magnetostriction characteristics, and a torque sensor using the magnetic core unit.

  For the power steering mechanism, engine control mechanism, power transmission mechanism, and the like of automobiles, a means for accurately detecting shaft torque has long been desired. By increasing the detection accuracy, precise control and efficiency can be improved, and various methods have been proposed so far. In particular, the method of detecting the shaft torque without contact using the magnetostrictive characteristics of the rotating shaft has a large overload capability, and is attracting attention as a method that replaces the conventional method of detecting the torque from the torsion amount of the torsion bar. .

  Various types of torque sensors of this type have been proposed, but all of them vary in permeability caused by torque, more specifically, + 45 ° and −45 ° with respect to the axial direction of the rotating shaft. The fluctuation of the magnetic permeability in the direction is detected by the detection coil. For example, in the technique disclosed in Patent Document 1, as shown in FIG. 35A, a magnetic film 503 having an inclination angle with respect to the axial direction is fixed to a rotating shaft 502 whose torque is to be detected. Excitation and detection are performed by the outer solenoid coil 504. However, since this method requires additional processing on the rotating shaft, there is a risk that reliability such as peeling of the magnetic film 503 may be impaired. Furthermore, since it is essential to specialize the shaft and increase the diameter, there is a problem that the mounting property is poor.

  For this reason, a torque sensor having a similar function without any processing on the rotating shaft has been proposed. For example, the technology disclosed in Patent Document 2 describes a structure in which a U-shaped iron core (magnetic core) is provided on the outer periphery of the rotating shaft 502 as shown in FIG. In this configuration, two types of magnetic cores, namely, excitation magnetic cores 505 and 507 and detection magnetic cores 506 and 508 are mounted close to the rotation shaft at an angle of ± 45 ° in the axial direction of the rotation shaft 502. . A coil is wound around each of the exciting magnetic core and the detecting magnetic core, and an inductance variation between the exciting magnetic core and the detecting magnetic core is detected. If this variation in inductance is caused by a change in the magnetic permeability of the rotating shaft due to the torque, the torque can be detected thereby. Therefore, if the rotating shaft is made of a material having magnetostrictive characteristics, torque can be detected without performing any processing on the rotating shaft.

  Furthermore, as an example of improving the above-described technique, Patent Document 3 discloses a technique for reducing the size of the apparatus and simplifying the winding work around the coil (hereinafter also referred to as “first reference”). In this technique, a magnetic core is formed by attaching a large number of magnetic pieces having protrusions to a magnetic ring with magnetic pins, and a coil is wound around each magnetic pin to form a torque sensor.

  Patent Document 4 discloses a technique for detecting torque with high accuracy while avoiding an increase in the size of the torque sensor (hereinafter also referred to as “second reference”). In this technique, an excitation (excitation) core and a detection core are formed on the inner peripheral surface of a ring core, and a coil is wound around each core.

  In Patent Document 5, for the same purpose as described above, two disk-shaped magnetic pole yokes having magnetic flux guiding arms (legs) and a cylindrical connection yoke for magnetically connecting the magnetic pole yokes are provided. A technique in which excitation and detection coils are provided inside a cylinder is disclosed (hereinafter also referred to as “third reference”).

  Patent Document 6 discloses a torque sensor in which three magnetic disks are spaced apart in parallel at a predetermined interval, their outer periphery is connected by a magnetic cylindrical case, and a coil wound around a bobbin is disposed inside. Has been. The three disks have openings formed so that the protrusions are arranged on the inner peripheral surface. As a result, a torque sensor with a simple structure is realized.

JP-A-1-94230 JP-A-4-31726 JP-A-63-90730 JP 2001-289719 A Japanese Patent Laid-Open No. 9-196679 JP-A 61-275630

  However, even with the improved techniques of the first to fourth references, there are still problems to be overcome.

  For example, in the first reference, the magnetic ring is an integral object, the cores adjacent in the circumferential direction are not separated, and noise is generated in the output due to magnetic interference. In addition, the number of parts is large and the assembly work is difficult, and the alignment accuracy is lowered. Moreover, since a coil is wound for each magnetic pin provided in large numbers, adjacent coils interfere with each other, and there is a limit to increasing the number of turns of the coil. Therefore, the output obtained is small and the sensitivity is low. In addition, there is an operation of winding a large number of coils, and it has been required to omit such an operation as much as possible from the viewpoint of reducing man-hours. Furthermore, it is very difficult to make the winding lengths of the coils uniform, and variations are inevitably generated, resulting in a decrease in output accuracy.

  In the second reference, the disks are integrated without being separated, and the magnetic cores are not separated when the pair of magnetic poles are regarded as magnetic cores. For this reason, there is a problem that noise is generated as described above, or that the component corresponding to the + 45 ° magnetic flux and the signal corresponding to the −45 ° magnetic flux cannot be separated.

  Also in the third reference example, adjacent magnetic cores are not separated, and similarly, there is a problem that noise is generated. Moreover, since the closest counter magnetic pole is parallel to the axial direction, a magnetic flux flows along the axial direction, and there is a problem in that output accuracy decreases. As a result, there is also a problem that it is difficult to appropriately suppress the zero point fluctuation.

  Furthermore, the torque sensor of the fourth example has a relatively simple structure in which the cylindrical connection portion is sandwiched between the disk-shaped yoke ends, but the disk is integrated and the magnetic core is not separated. It was. Therefore, there is a problem that noise occurs in the output as described above.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a technique for separating adjacent magnetic cores and facilitating assembly of components in a magnetostrictive torque sensor. There is.

The apparatus which concerns on this invention is related with the magnetic core unit used for a torque sensor. The magnetic core unit includes a cylindrical yoke connecting portion in which nonmagnetic portions and soft magnetic portions are alternately arranged in the circumferential direction, and a nonmagnetic portion and a soft magnetic portion that are attached to both ends of the yoke connecting portion. A substantially annular yoke portion alternately arranged in the direction is provided, and the soft magnetic portion of the yoke connecting portion and the soft magnetic portion of the yoke portion constitute a set of magnetic cores.
The yoke portion may have a shaft hole at the center, and the soft magnetic portion may extend linearly from a side surface of the shaft hole toward a radially outer side of the yoke connecting portion.
The yoke connecting portion may be provided such that the soft magnetic portion is in contact with the soft magnetic portion of the yoke portion in a state where the yoke portion is attached to an end portion.
Further, in a state where the yoke portion is attached to the end portion of the yoke connecting portion, the soft magnetic portion of the yoke connecting portion and the soft magnetic portion of the first yoke portion may constitute a set of magnetic cores. .
Further, the two yoke portions attached to both ends of the yoke connecting portion may have the same shape.
The yoke portion may be fitted to an end portion of the yoke connecting portion.
Further, a line connecting the centers of the end surfaces on the shaft hole side of the two yoke portions in a state where the yoke portion is attached to the end portion of the yoke connecting portion is a predetermined angle with the axial direction of the shaft hole. May be made.
Further, the predetermined angle may be set to approximately 45 °.
A plurality of the magnetic cores may be magnetically separated.
The material of the soft magnetic part may be Mn—Zn based ferrite.
The device according to the present invention relates to a torque sensor. The torque sensor includes the magnetic core unit described above, and has an inner coil for excitation and an inner coil for detection on the inner periphery of the yoke connection portion, and an excitation coil on the outer periphery of the cylindrical yoke connection portion. It has an outer peripheral coil and a detection outer peripheral coil.
Further, a first magnetic core unit in which the predetermined angle is set to about + 45 ° and a second magnetic core unit in which the predetermined angle is set to about −45 ° may be provided.
In addition, a cylindrical outer yoke portion made of a material capable of forming a magnetic path may be provided, and the outer yoke portion may be provided inside the magnetic core unit with magnetic separation.
Moreover, you may have an annular | circular shaped magnet in the outer peripheral part of the said exterior yoke part.
The exterior yoke portion includes an annular magnet provided on one end surface of the exterior yoke portion and having the same diameter as the shaft hole of the yoke portion, and a coil disposed on the inner surface of the exterior yoke portion. You may have.
Moreover, you may have the coil distribute | arranged to the outer surface of the said exterior yoke part.
In addition, an annular magnet provided on one end surface of the exterior yoke portion and having substantially the same diameter as the shaft hole of the yoke portion, and magnetically separated from the exterior yoke portion on the other end surface of the exterior yoke portion. The coil may be provided in a state of being made.
The apparatus which concerns on this invention is related with the yoke part used for the magnetic core unit of a torque sensor. The yoke portion has a substantially annular shape in which non-magnetic portions and soft magnetic portions are alternately arranged in the circumferential direction, and a shaft hole is provided in the center of the annular shape, and the soft magnetic portion includes the shaft hole. It extends linearly from the side surface toward the radially outer side of the yoke connecting portion.
The device according to the invention relates to a yoke connection. The yoke connecting portion has a cylindrical shape in which nonmagnetic portions and soft magnetic portions are alternately arranged in the circumferential direction.

  According to the present invention, in a magnetostrictive torque sensor, it is possible to separate adjacent magnetic cores and to easily assemble components.

  Next, the best mode for carrying out the present invention (hereinafter simply referred to as “embodiment”) will be specifically described with reference to the drawings.

  First, a basic operation principle (hereinafter referred to as “basic technology”) of the torque sensor will be described, and then a characteristic structure of the present embodiment to which the basic technology is applied will be described.

(Basic technology)
(1. Magnetic core)
FIG. 1 is a perspective view of a magnetic core in the basic technique, and FIG. 2 is a side view thereof. However, in FIG. 2, this magnetic core is seen from the direction of the arrow on the left side in FIG. 1, and is turned upside down. The magnetic core 30 includes a plate-like back yoke portion 31 and two leg-like yoke portions 32. The magnetic core 30 is used in a torque sensor that measures torque applied to the rotating shaft without contact.

  The plate-like back yoke portion 31 and the two leg-like yoke portions 32 are integrally formed of a soft magnetic material. As the soft magnetic material, for example, Mn—Zn ferrite is preferably used. For this reason, in the torque sensor using this magnetic core 30, this magnetic core 30 can form a magnetic path.

  The plate-like back yoke portion 31 serves as a support portion for the magnetic core 30 and has a thickness that can maintain sufficient rigidity. For example, the thickness can be 5 mm to 10 mm. The plate-like back yoke portion 31 has a substantially square surface. Here, the surface is a surface perpendicular to the thickness direction. In this case, the length of one side of the square is about the same as the diameter of the rotating shaft that detects torque, and can be about 20 mm, for example. However, the plate-like back yoke portion 31 does not need to be configured in a plane, and can have any shape as long as the rigidity of the magnetic core 30 can be ensured and an effective magnetic path can be formed.

  The two leg-like yoke portions 32 are formed in the vicinity of the apexes of the square diagonal relationship on the surface of the plate-like back yoke portion 31 and extend downward (upward in FIG. 1) substantially perpendicularly from this surface. Formed with. The shape of the cross section is arbitrary as long as it can form an effective magnetic path, but the maximum diameter of the cross section is made smaller than the diameter of the rotating shaft. The cross-sectional shape can be a square having a side of about 7 mm, for example. In this case, it is preferable from the viewpoint of manufacturing that each side of the square in the cross section is substantially parallel to each side of the square in the plate-like back yoke portion 31. The length of the leg-shaped yoke portion 32 is arbitrary as long as it is an effective magnetic path and sufficient mechanical strength is maintained. For example, the length can be set to about 15 mm. If it is long, the strength becomes a problem, and the torque sensor using this becomes large. On the other hand, when the length is short, it is not possible to increase the number of turns of the exciting coil for winding the leg-shaped yoke and the detection coil described later.

  The bottom surfaces 33 (uppermost surfaces in FIG. 1) of the two leg-like yoke portions 32 are both composed of two types of surfaces, a first surface 33a and a second surface 33b.

  The first surface 33 a is a flat surface that is substantially parallel to the surface of the plate-like back yoke portion 31. Further, this surface is also substantially perpendicular to the longitudinal direction of the leg-like yoke portion 32.

  The second surface 33b is inclined from the first surface 33a. Since the second surface 33b is provided to bring the bottom surface 33 close to the rotating shaft that detects torque, the inclination angle corresponds to the shape of the surface of the rotating shaft that detects torque using the magnetic core. Yes. Thereby, the whole 2nd surface 33b can be made to adjoin to a rotating shaft. In other words, the second surface 33b can increase the portion where the bottom surface 33 of the magnetic core 30 is close to the rotation axis. Since the bottom surface of the leg-shaped yoke portion 32 has such a configuration, the magnetic flux penetrating the magnetic core can be efficiently incident on the rotating shaft, and the leakage of the magnetic flux can be reduced. The sensitivity of the torque sensor can be increased.

  Therefore, the second surface 33b is preferably a cylindrical shape having a curvature corresponding to the shape of the surface of the rotating shaft. Specifically, on the bottom surface 33 (second surface 33b), the sum of the distance between the rotation axis and the radius of the rotation axis can be set as the curvature radius. This interval can be set to 1 mm, for example. However, the present invention is not limited to this. For example, when the diameter of the rotation shaft is larger than the entire size of the bottom surface 33, the second surface 33b may be a flat surface inclined from the first surface 33a. . This corresponds to a case where the radius of curvature is infinite.

(2. Torque sensor)
A highly sensitive non-contact torque sensor can be configured using the magnetic core described above. In this torque sensor, the bottom surface (second surface) of the magnetic core is installed close to the rotating shaft, a magnetic field is applied to the magnetic core by the exciting coil, and a part of the rotating shaft is in this magnetic path. included. When torque is applied to the rotating shaft due to the torque, and the magnetic permeability of the rotating shaft varies, the inductance between the detection coil and the exciting coil varies. Thereby, this stress can be detected and torque can be calculated. In this case, a plurality of forms of torque sensors described below can be realized.

  3 and 4 are diagrams showing the structure of the torque sensor 10 in the basic technique. FIG. 3 is a front view (partially sectional view) viewed from a direction perpendicular to the axial direction of the rotation shaft. FIG. 4 is a side front view (partially sectional view) seen from the axial direction of the rotating shaft. Note that some of the components are omitted in FIG.

  In this example, the torque sensor 10 detects the torque applied to the rotating shaft 90. Here, four magnetic cores are installed in two locations in the circumferential direction of the rotating shaft. Here, the first measurement unit (first detection unit) 20 on the left side in FIG. 3 measures the permeability change in the + 45 ° direction from the axial direction of the rotation axis, and the second measurement unit (second measurement unit) on the right side in the figure. The detection unit 120 measures a change in magnetic permeability in a −45 ° direction (a direction perpendicular to the first measurement unit). By measuring the change in magnetic permeability in these two directions, the direction and magnitude of the torque applied to the rotating shaft can be detected. For this reason, in this torque sensor 10, a magnetic path including a magnetic core and a part of the rotating shaft is formed, and the change in the permeability on the rotating shaft caused by the magnetostrictive effect due to the torque is the change in inductance in this magnetic path. Detected. For this reason, the rotating shaft 90 is made of a magnetostrictive material, for example, chrome molybdenum steel. This material is a material generally used as a crankshaft material in an automobile engine, for example, and has sufficient mechanical strength. Therefore, it is not necessary to perform special processing for a torque sensor on the rotating shaft.

  When torque is applied to the rotating shaft 90, tensile stress and compressive stress are generated in directions of + 45 ° and −45 ° (a direction perpendicular to the direction) with respect to the axial direction of the rotating shaft 90. When tensile stress is applied to a material having a positive magnetostriction coefficient, the permeability increases due to the magnetostriction effect. Conversely, when compressive stress is applied, the magnetic permeability decreases. That is, when the rotation axis is a part of the magnetic path, the change in inductance can be detected by the detection coil, and the stress in these directions can be measured. From these two directions of stress, the direction and magnitude of the torque applied to the rotating shaft 90 can be measured. A specific method for detecting torque by this method is described in, for example, Japanese Patent Laid-Open No. 4-31726. This torque sensor is particularly characterized by its configuration and method for detecting a change in magnetic permeability.

  The magnetic cores 30, 40, 50, 60 used in the first measurement unit 20 have the same shape as the magnetic core 30 in FIG. 1, and these have the same shape. Since the magnetic core 60 is located on the opposite side across the rotation shaft 90, it is not shown in FIG. 3, and the same applies to the components described below. These are composed of plate-like back yoke portions 31, 41, 51, 61, two leg-like yoke portions 32, 42, 52, 62, and bottom surfaces 33, 43, 53, 63, respectively. Each bottom surface includes a first surface 33a, 43a, 53a, 63a and a second surface 33b, 43b, 53b, 63b.

  As shown in FIG. 4, the second surfaces 33 b, 43 b, 53 b, and 63 b are installed close to the rotating shaft 90 with the distance from the rotating shaft 90 being g. For this reason, the second surfaces 33b, 43b, 53b, 63b are correspondingly cylindrical curved surfaces, and the radius of curvature is equal to the sum of the radius of the rotating shaft 90 and the interval g.

  As shown in FIG. 3, for example, a line connecting the centers of the bottom surfaces of the two leg-shaped yoke portions 42 in the magnetic core 40 forms an angle of 45 ° with the axial direction of the rotation axis. The magnetic cores 30, 50 and 60 have the same shape as the magnetic core 40, and thus are the same as described above.

  In the first measurement unit 20, an excitation inner peripheral coil 71 and an excitation outer peripheral coil 72 are used as excitation coils. The exciting inner peripheral coil 71 is wound in the outer peripheral direction of the rotary shaft 90 so as to pass inside the respective plate-like back yoke portions 31, 41, 51, 61. The excitation outer peripheral coil 72 is wound in the outer peripheral direction of the rotary shaft 90 so as to pass outside the respective plate-like back yoke portions 31, 41, 51, 61.

  Similarly, in the first measurement unit 20, a detection inner peripheral coil 81 and a detection outer peripheral coil 82 are used as inductance detection coils. The detection inner peripheral coil 81 is wound in parallel with the excitation inner peripheral coil 71 so as to pass inside the respective plate-like back yoke portions 31, 41, 51, 61. The detection outer coil 82 is wound outside the plate-like back yoke portions 31, 41, 51, 61 in parallel with the excitation outer coil 72. 3 and 4 may be realized by incorporating a bobbin around which these coils are wound, for example, as a form wound around a bobbin. In this case, for excitation, Two types are used: a bobbin around which an inner peripheral coil 71 and a detection inner peripheral coil 81 are wound, and a bobbin around which an excitation outer peripheral coil 72 and a detection outer peripheral coil 82 are wound. Further, the exciting coil and the detecting coil may be separated and four types of bobbins may be used, and these may be incorporated.

  Furthermore, as shown in FIG. 4, the entire first measurement unit 20 is accommodated in a housing 91 (not shown in FIG. 4), and the inner peripheral surface 92 of the housing 91 is the second surfaces 33b, 43b, 53b. , 63b to be consistent with each other. For this reason, the magnetic core 30 and the like, the excitation inner peripheral coil 71 and the like are fixed in the housing 91 by using a molding material (not shown).

  The housing 91 is preferably formed of a nonmagnetic material so as not to affect the magnetic circuit formed by the coils and the magnetic cores. As this material, for example, a heat-resistant resin material, an aluminum alloy, or a copper alloy can be used.

  The housing 91 is provided with a lead-out portion 93, in which an external circuit 94 is provided. The external circuit 94 is connected with an excitation inner peripheral coil 71 and an excitation outer peripheral coil 72, a detection inner peripheral coil 81 and a detection outer peripheral coil 82. As a result, an exciting current is supplied to the exciting inner peripheral coil 71 and the exciting outer peripheral coil 72, and output signals from the detecting inner peripheral coil 81 and the detecting outer peripheral coil 82 are obtained.

  Further, the entire first measurement unit 20 has fixing bolts (not shown) passed through fixing bolt holes 95 provided at three locations around the housing 91, and is screwed to an external fixing location (not shown). It is fixed by doing.

  In the first measurement unit 20, a change in magnetic permeability at an angle of 45 ° with the axial direction of the rotating shaft 90 is detected. Thereby, it is possible to calculate the direction (tensile stress or compressive stress) and the magnitude of the stress in this direction.

  On the other hand, the second measurement unit 120 has the same structure as the first measurement unit 20. That is, the magnetic cores 130, 140, 150, 160 having the same shape as the magnetic core 30 in FIG. These are composed of plate-shaped back yoke portions 131, 141, 151, 161, two leg-shaped yoke portions 132, 142, 152, 162, and bottom surfaces 133, 143, 153, 163, respectively. Each bottom surface includes a first surface 133a, 143a, 153a, 163a and a second surface 133b, 143b, 153b, 163b. Further, similarly to the first measurement unit 20, it has an inner coil for excitation 171, an outer coil for excitation 172, an inner coil for detection 181, and an outer coil for detection 182.

  The line connecting the two leg-shaped yoke portions 132 (bottom surfaces 133) of the magnetic core 130 used in the second measurement unit 120 forms an angle of 45 ° with the axial direction of the rotation axis. 20 differs from the angle at the magnetic core 30 by 90 °. That is, the stress in the direction of + 45 ° with respect to the axial direction of the rotary shaft 20 is detected by the magnetic core 30 in the first measurement unit 20, whereas the direction of −45 ° is detected by the magnetic core 130 in the second measurement unit 120. The stress is detected. The same applies to the magnetic cores 140, 150, and 160. That is, by using the magnetic core having this configuration, the stress in the −45 ° direction is detected by the second measurement unit 120.

  In the torque sensor 10, it is necessary to generate a magnetic field with the exciting coil and detect a change in inductance with the detecting coil. For this reason, in this torque sensor 10, a strong magnetic field is generated in each magnetic core by using two coils, the inner coil for excitation 71 and the outer coil for excitation 72, as the exciting coils.

  Thereby, for example, in the magnetic core 30, a magnetic field indicated by the magnetic flux 96 in FIG. 3 is induced. This magnetic path includes a rotating shaft 90 in a part thereof. The same applies to the magnetic cores 40, 50 and 60. By detecting the inductance using two coils of the detection inner coil 81 and the detection outer coil 82 as the detection coils, a change in the magnetic permeability in the rotating shaft 90 is detected as a change in the inductance. Can do. From the change in inductance, the first measurement unit 20 can calculate the stress (first stress) in the + 45 ° direction that is the direction of the magnetic path on the rotating shaft 90. Similarly, the stress in the −45 ° direction (second stress) can be calculated by the second measurement unit 120. From these two types of stress, the torque applied to the rotating shaft 90 is calculated.

(3. Principle)
The principle of the induction of the magnetic field shown in FIG. 3 will be described in detail below. FIG. 5 shows two magnetic cores 30 and 50 positioned above and below the rotating shaft 90 of FIG. 3 for easy understanding. Hereinafter, the upper magnetic core 30 will be described. Here, in order to explain the induction of the magnetic field, an excitation inner peripheral coil 71 and an excitation outer peripheral coil 72 which are excitation coils are illustrated. Further, FIG. 6 is a diagram for explaining the induction of the magnetic field by the excitation inner peripheral coil 71, and FIG. 7 is a diagram for explaining the induction of the magnetic field by the excitation outer peripheral coil 72. Therefore, FIG. 5 shows the magnetic field displayed by combining the magnetic fields of the inner coil 71 for excitation and the outer coil 72 for excitation. In general, the state of the magnetic field is indicated by a plurality of magnetic field lines. A bundle of magnetic field lines corresponds to a magnetic flux, but in order to make the drawing easier to see, main magnetic field lines are indicated by arrows. Hereinafter, this line of magnetic force is referred to as “magnetic flux”.

  First, induction of a magnetic field by the exciting inner coil 71 will be described with reference to FIG. When a current flows through the exciting inner coil 71 in the direction shown (the direction toward the front), a counterclockwise magnetic field is generated in the vicinity of the magnetic core 30 according to the right-hand rule of electromagnetics. Since the magnetic lines of force in the magnetic field are concentrated in the magnetic path having a high magnetic permeability, a magnetic flux 96m passing through the magnetic core 30 and a magnetic flux 97m passing through the outer periphery of the magnetic core 30 and the rotating shaft 90 are generated.

  FIG. 8 corresponds to a view (top view) of the magnetic core 30 of FIG. 6 viewed from the plate-like back yoke portion 31 side. Here, the illustration of the inner coil for excitation 71 is omitted. As shown in the drawing, when a torque T in the counterclockwise direction in the left side view is applied to the left side of the rotating shaft 90, a stress σ is generated in the rotating shaft 90 in an oblique direction. Specifically, an upper left and lower right tensile stress σ + and an upper right and lower left compressive stress σ− are generated. In general, when a stress σ is generated as a material of the rotating shaft 90, the permeability of the rotating shaft 90 decreases in the direction in which the compressive stress σ− is applied, and the rotating shaft 90 in the direction in which the tensile stress σ + is applied. For example, the above-described chromium molybdenum steel is selected.

  Along with the direction of the generated stress σ, as shown in the figure, the leg-shaped yoke portions 32 that are the legs of the magnetic core 30 are arranged on the diagonal of the square, so that a high output can be obtained. FIG. 9 is a graph showing the relationship between the magnetic field strength H applied to the rotating shaft 90 and the magnetic flux density B in the rotating shaft 90.

  Here, in order from the top, the BH curve C1 to which the tensile stress σ + is applied, the BH curve C2 when the stress is zero, and the BH curve C3 to which the compressive stress σ− is applied are shown. As can be seen from this graph, when the BH curves C1 and C3 when the tensile stress σ + and the compressive stress − are applied are compared, the BH curve C3 when the compressive stress σ− is applied has zero stress. The amount of change from the BH curve C2 is large. Therefore, it is desirable to see the change in permeability along the direction of compressive stress σ− rather than tensile stress σ +. Therefore, as shown in FIGS. 6 and 8, the two leg yoke portions 32 are arranged on the diagonal line in the direction of the compressive stress σ−.

  Next, the induction of the magnetic field by the excitation outer coil 72 will be described with reference to FIG. As shown in FIG. 7A, when a current flows through the exciting outer coil 72 in the direction shown (the direction toward the back), a clockwise magnetic field is generated in the vicinity of the magnetic core 30 according to the right-hand rule of electromagnetics. appear. Since the magnetic lines of force in the magnetic field are concentrated in the magnetic path having a high magnetic permeability, a clockwise magnetic flux 96n1 to 96n5 passing through the magnetic core 30 and a magnetic flux 97n passing through the outer periphery of the magnetic core 30 and the rotating shaft 90 are generated.

  The magnetic fluxes 96n1 to 96n5 have a magnetic flux component that passes from the right leg yoke portion 32 to the plate-shaped back yoke portion 31 and the left leg yoke portion 32. When these magnetic flux components are represented by a magnetic equivalent circuit, they can be understood as a magnetic flux 96n having a magnetic core 30 as a path and a magnetic flux 97n having a magnetic core outer periphery as a path, as shown in FIG. 7B.

  Then, when the magnetic fluxes shown in FIGS. 6 and 7B are added together, distributions of magnetic fluxes 96m, 96n, 97m, and 97n as shown in FIG. 5 are obtained. Magnetic fluxes generated around the magnetic core 30 are counterclockwise magnetic flux 97m and clockwise magnetic flux 97n, which cancel each other and become zero. Further, two counterclockwise magnetic fluxes 96m and 96n passing through the magnetic core 30 are added together to form a magnetic flux 96 shown in FIG. The magnetic flux 96 does not cross the detection outer coil 82 and therefore does not contribute to the output of the detection outer coil 82. However, the presence of the detection outer peripheral coil 82 improves the balance of the magnetic circuit, as will be described later. That is, in the case where only the detection inner coil 81 is configured, both the magnetic circuit that passes through the magnetic core 30 and the magnetic circuit that does not pass through the magnetic core 30 are detected in consideration of the output impedance of the detection-side circuit. become. As a result, when there is an unbalanced magnetic body or magnetic flux source different from the torque sensor 10 in the vicinity of the rotating shaft 90, it is likely to be influenced by them. On the other hand, when the detection inner peripheral coil 81 and the detection outer peripheral coil 82 exist as described above, detection is performed for magnetic noise from a magnetic flux source or the like away from the magnetic core 30. The interlinkage magnetic flux to the inner coil 81 for detection and the outer coil 82 for detection becomes substantially the same. Therefore, in the output voltages at the detection inner peripheral coil 81 and the detection outer peripheral coil 82, the magnetic noise appears as a negative phase voltage and cancels out.

  FIG. 10 is a diagram showing the relationship between the torque applied to the rotating shaft 90 and the magnetic flux (linkage magnetic flux) detected by the detection coil. FIG. 10A shows the magnetic flux of the magnetic field excited by each of the exciting inner coil 71 and the exciting outer coil 72 in FIG. 5, and the curve C11 showing the upper chevron is the exciting outer coil. The magnetic flux 97m by 72 is shown, and the lower curve C12 shows the magnetic flux 96m by the inner coil 71 for excitation.

  The magnetic circuit corresponding to the excitation outer coil 72 has a large magnetic resistance when considered in terms of an axial cross section, but the magnetic circuit cross sectional area is also large, that is, the cross sectional area through which the magnetic flux 97m passes is large. On the other hand, the magnetic circuit corresponding to the excitation inner peripheral coil 71 has a small magnetic resistance because of the closed magnetic circuit, but has a small cross-sectional area through which the generated magnetic flux 96m passes, so that the magnetic flux affected by the permeability change is small. Here, the ratio of the magnetic flux 97 m generated by the exciting outer peripheral coil 72 to the magnetic flux 96 m generated by the exciting inner peripheral coil 71 is about 5: 1.

  Actually, since the magnetic flux 97m generated by the excitation outer peripheral coil 72 and the magnetic flux 96m generated by the excitation inner peripheral coil 71 are not separated, two magnetic fluxes 96m and 97m are synthesized as shown in FIG. The state magnetic flux (curve C13) is measured. As shown here, since the output is substantially symmetrical, it is difficult to determine the direction of torque application (+, −).

  Further, the magnetic flux corresponding to FIG. 7 is measured in the same graph as in FIGS. 10 (a) and 10 (b). However, as described above, the magnetic flux generated around the magnetic core 30 is the counterclockwise magnetic flux 97m and the clockwise magnetic flux 97n, and the two magnetic fluxes 96m and 97m cancel each other. Since the two counterclockwise magnetic fluxes 96m and 96n passing through the magnetic core 30 have the same direction of the magnetic flux, the two magnetic fluxes 96m and 96n are added together. Therefore, when the magnetic fluxes of FIGS. 6 and 7 are superimposed, a graph indicated by a curve C14 is obtained as shown in FIG. Thus, the direction of torque can be determined by obtaining a curve C14 that rises to the right.

FIG. 11 is a diagram showing a circuit connection in which the inner coil for excitation 71 and the outer coil for excitation 72 are connected in series in the torque sensor 10, and FIG. The circuit connection which has connected the outer periphery coil 72 for parallel is shown. For example, in the case of the serial connection mode shown in FIG. 11, the first output V _L1 detected by the first measurement unit 20 and the second output V _R1 detected by the second measurement unit 120 are connected to the synchronous detection circuit 99a. As is input to the operational amplifier 99b. As a result, a final output V _O1 is obtained. Note that the second output _{V R1} is the inverting input to the operational amplifier 99b. FIG. 13 is a diagram showing the relationship between the applied torque T, the first output V _L1 , the second output V _R1 , and the final output V _O1 . As shown in FIG. 12, even when the excitation inner peripheral coil 71 and the excitation outer peripheral coil 72 are connected in parallel, the first output V _L2 detected by the first measurement unit 20 and the second measurement unit 120 The detected second output V _R2 passes through the synchronous detection circuit 99a and is input to the operational amplifier 99b to obtain the final output V _O2 . This final output V _O2 is about twice as large as the final output V _O1 when connected in series.

  In order to make the torque sensor 10 highly sensitive, it is necessary that the magnetic core and the rotating shaft 90 be brought as close as possible so that the magnetic flux can enter the measurement site on the rotating shaft 90 without leakage. For this, as shown in FIG. 4 and the like, since the second surfaces 33b and the like are provided in each magnetic core, the interval (g) between the rotating shaft 90 and the second surface is small and accurate. It is possible to keep. Thereby, the leakage of the magnetic flux can be reduced.

  In the torque sensor 10, in the first measurement unit 20 and the second measurement unit 120, four magnetic cores having the same shape are arranged around the rotation shaft. For example, in FIG. 4, the magnetic path penetrating the magnetic core 30 is formed between the magnetic core 30 and C-C ′ in the rotating shaft 90 (between the bottom surface 33). Therefore, the location where the change in magnetic permeability is detected is between C and C ′ on the rotating shaft 90. Similarly, the locations where the change in permeability is detected by the other magnetic cores 40, 50, 60 are between the bottom surfaces 43, between the bottom surfaces 53, and between the bottom surfaces 63, but these magnetic paths are the excitation inner peripheral coil 71. The change in inductance in the magnetic path formed by flowing current through the excitation outer coil 72 and including these four magnetic cores is detected by the detection inner coil 81 and the detection outer coil 82. Thereby, the average value of the change of the magnetic permeability in four detection locations is obtained. Thereby, even if the material inhomogeneity exists inside the rotating shaft 90, the average value of the stress is calculated. Therefore, it is possible to detect torque with high sensitivity.

  On the other hand, for example, when a magnetic core having four leg-shaped yoke portions described in JP-A-7-190866 is used, the magnetic permeability change in the + 45 ° direction and −45 with a single magnetic core. Detects changes in permeability in the direction of °. For this reason, when a plurality of the magnetic cores are arranged around the rotation axis, the influence of the magnetic field for detecting the magnetic permeability in the opposite direction in the adjacent magnetic cores appears, so that high-sensitivity measurement is difficult. In addition, since the exciting coil and the detecting coil are wound on the same leg in the four-leg structure, it is difficult to increase the number of turns of these coils to increase the sensitivity.

  Further, in order to obtain this high sensitivity characteristic with good reproducibility, as described above, it is necessary to reduce the distance (g) between the bottom surface 33 and the like of the magnetic core 30 and the rotating shaft 90 and install it with high accuracy. . On the other hand, in the conventional magnetic core having the four-leg structure, it is necessary to accurately manufacture the bottom surfaces of the four legs. In the torque sensor 10, there are two bottom surfaces to be considered when installing the magnetic core 30. For this reason, high precision is not required in the manufacture of the magnetic core, and it is easy to install the magnetic core close to the rotating shaft at a predetermined interval. That is, it is possible to easily realize a torque sensor that can obtain high sensitivity characteristics with good reproducibility.

  When the torque sensor 10 is manufactured, each magnetic core, each coil, the external circuit 94, and the like are placed in a mold and molded integrally with a heat resistant resin material. At this time, by providing a fixing partition plate on the inner side (the same side as the rotating shaft 90) and removing it after molding, it is possible to fix each magnetic core particularly accurately. At this time, it is preferable that a cover having the same shape as the housing 91 is fixed to the housing 91.

  The number of magnetic cores having the same shape used in a single measurement unit is arbitrary. In addition, the interval (angle) at which this is installed is 90 ° in the above example, but this is also arbitrary and may not be equal.

(First embodiment)
Based on the above basic technology, in the present embodiment, a measurement unit suitable for being housed in the housing 91 shown in FIG. 4 will be mainly described. This measurement unit is used for the first and second measurement units 20 and 120 in the basic technology.

  FIG. 14 is a perspective view showing an external appearance of the measurement unit 200. FIG. 15 is a perspective view showing the measurement unit 200 in a state where it is disassembled into components. 16 is a three-side view and a cross-sectional view of the measurement unit 200. FIG. 16 (a) is a plan view, FIG. 16 (b) is a front view, FIG. 16 (c) is a bottom view, and FIG. Shows a cross-sectional view.

  The measurement unit 200 includes a cylindrical magnetic head 210, an outer peripheral bobbin 211 attached to the outside of the magnetic head 210, and an inner peripheral bobbin 213 disposed inside the magnetic head 210. A shaft hole 228 into which the rotation shaft can be inserted is formed at the center of the cylindrical shaft of the magnetic head 210.

  The outer peripheral bobbin 211 is wound with a predetermined amount of the outer peripheral coil 212a for excitation and the outer peripheral coil 212b for detection. On the inner peripheral bobbin 213, an excitation inner peripheral coil 214a and a detection inner peripheral coil 214b are wound by a predetermined amount.

  FIG. 17 is a perspective view showing only the appearance of the magnetic head 210 with the outer peripheral bobbin 211 and the inner peripheral bobbin 213 removed. The magnetic head 210 is composed of three elements: an annular first yoke part 220a and a second yoke part 220b, and a cylindrical yoke connecting part 240. The first yoke part 220a and the second yoke part 220b are the same component, and are fitted to the two openings of the yoke connecting part 240 so as to face each other, thereby closing the openings.

  18A and 18B are a three-side view and a cross-sectional view of the first yoke portion 220a. FIG. 18A is a plan view, FIG. 18B is a front view, FIG. 18C is a bottom view, and FIG. Shows a cross-sectional view. The first yoke portion 220a has a shape in which three large, medium, and small rings are concentrically overlapped. The outer peripheral connection portion 221 that is formed in a ring shape on the lowermost side is the shape having a diameter R11 (for example, 60 mm) and a height h11 (for example, 2 mm). The height h11 is based on the bottom surface 224 of the outer peripheral connection portion 221, and the following heights h12 and h13 are the same.

  The second largest bobbin housing 222 formed in a ring shape at the center has a diameter R12 (for example, 44 mm) and a height h12 (for example, 3 mm). The outer peripheral diameter R12 corresponds to the inner peripheral diameter of the outer peripheral connection portion 221. Therefore, a step having a height h12-h11 (for example, 1 mm) is formed between the outer peripheral connection portion 221 and the bobbin housing portion 222.

  Further, the shaft insertion portion 223 formed in a ring shape on the innermost side is formed such that the shaft insertion portion 223 whose outer periphery has a diameter R13 has a height h13 (for example, 10 mm). The outer diameter R13 corresponds to the inner diameter of the bobbin housing 222. Therefore, a step having a height h13-h12 (for example, 7 mm) is formed between the bobbin housing portion 222 and the shaft insertion portion 223. In addition, the above-described shaft hole 228 having a diameter (caliber) R14 (for example, 20 mm) is formed in the center of the circle of the first yoke portion 220a so as to penetrate vertically. Further, an inner peripheral bobbin 213 having substantially the same inner diameter as the outer diameter (diameter R13) of the shaft insertion portion 223 is fitted into the shaft insertion portion 223.

  The first yoke portion 220a is formed of two soft magnetic portions (232a1, 232a2) and two nonmagnetic portions 231a. Specifically, the first and second soft magnetic portions 232a1, 232a2 (hereinafter referred to as the first and second soft magnetic portions 232a1) linearly with a predetermined width d11 (for example, 10 mm) in a diameter portion in a top view. 232a2 is simply referred to as “soft magnetic portion 232”. The first and second soft magnetic portions 232a1 and 232a2 are separated by a central shaft hole 228. In the drawing, the first soft magnetic part 232a1 is formed on the left side, and the second soft magnetic part 232a2 is formed on the right side. When the first and second yoke portions 220a and 220b are not distinguished, they are simply referred to as yoke portions 220. Further, as described above, the second yoke portion 220b is the same as the first yoke portion 220a, and is formed of the first and second soft magnetic portions 232b1 and 232b2 and the two nonmagnetic portions 231b.

  As the material for the soft magnetic part 232, pure iron powder, Fe—Al—Si based sendust powder, amorphous metal powder that is an Fe-based nanocrystalline material, and the like are preferable, and the particle size of these materials is preferably 200 μm or less.

  Further, two substantially semicircular non-magnetic portions 231 a are formed so as to be separated by the soft magnetic portion 232. As the material of the nonmagnetic part 231a, a Cu—Zn alloy such as brass, an Al—Si alloy, or the like is preferable, and the particle diameter of these materials is preferably 200 μm or less. Moreover, the soft magnetic part 232 and the nonmagnetic part 231a are formed separately as temporary molded bodies, respectively, and the soft magnetic part 232 and the nonmagnetic part 231a are alternately combined and formed into a ring shape by main molding under high pressure. A thermoplastic resin having an average particle size of 100 μm or less can be used as the binder in consideration of dispersibility in each material powder. Furthermore, four through holes 229 having a predetermined size (for example, a diameter of 3.5 mm) are formed in the outer peripheral connection portion 221 at positions of 0 °, 90 °, 180 °, and 270 ° at intervals of 90 °. The two through holes 229 formed at 90 ° and 270 ° are formed in the soft magnetic part 232. A through-hole 229 is also formed in the second yoke part 220b at the same position as the first yoke part 220.

  19A and 19B are a three-side view and a cross-sectional view of the yoke connecting portion 240. FIG. 19A is a plan view, FIG. 19B is a front view, FIG. 19C is a bottom view, and FIG. A cross-sectional view is shown. The yoke connecting portion 240 has a ring shape (cylindrical shape), and the outer periphery has a diameter R21 and the inner periphery has a diameter R22. Further, the shape (plan view) of the yoke connecting portion 240 in a top view is the same as the shape of the outer peripheral connecting portion 221 of the first yoke portion 220. That is, the diameter R21 of the outer periphery of the yoke connecting portion 240 is the same as the diameter R11 of the outer periphery of the first yoke portion 220. Further, the inner diameter R22 of the yoke connection portion 240 is the same as the inner periphery of the outer periphery connection portion 221 of the yoke connection portion 240 and the outer periphery of the bobbin housing portion 222 (R22 = R12). Then, the ring-shaped plane portion of the yoke connecting portion 240 and the outer peripheral connecting portion 221 of the first yoke portion 220 are combined, and the yoke connecting portion 240 and the first yoke portion 220 are fitted.

  Similarly to the first yoke part 220a, the yoke connecting part 240 can be divided into two soft magnetic parts 252 and two non-magnetic parts 251 by the constructed material, and the yoke connecting part 240 is rotated from 90 ° in the circumferential direction of the rotation axis. It is divided into four at slightly shifted intervals. Specifically, in the plan view of FIG. 19 (a), from a position that advances in the clockwise direction by a predetermined amount x11 from 0 ° of the ring shape, to a position that returns in the counterclockwise direction by a predetermined amount x11 from 90 °. The first nonmagnetic portion 251 is formed. This predetermined amount x11 is half of the width d11 of the soft magnetic portion 232 of the first yoke portion 220a described above (x11 = d11 / 2).

  A first soft magnetic portion 252 is formed from a position at which the non-magnetic material 251 is interrupted to a position advanced in the clockwise direction by a predetermined amount x11 from 180 °. A second nonmagnetic portion 251 is formed from the position where the first soft magnetic portion 252b is interrupted to the position where the first soft magnetic portion 252b is returned counterclockwise by a predetermined amount x11 from 270 °. Then, the second soft magnetic part 252b is formed from a position where the nonmagnetic part 251 is interrupted to a position advanced by 0 ° by a predetermined amount x11, that is, a position where the first nonmagnetic part 251 is formed. The In other words, the first and second soft magnetic portions 252a and 252b are larger in the circumferential direction by a predetermined amount x11 than the size obtained by dividing the ring shape into four parts. Accordingly, both end portions of the nonmagnetic portion 251 are smaller by a predetermined amount x11 than the size of the ring shape divided into four. When the first and second soft magnetic portions 252a and 252b are not distinguished from each other, they are simply referred to as soft magnetic portions 252. The materials for the soft magnetic portion 252 and the nonmagnetic portion 251 of the yoke connecting portion 240 and the procedure for forming the yoke connecting portion 240 using the soft magnetic portion 252 and the nonmagnetic portion 251 are the materials and formation relating to the first yoke portion 220. The procedure may be the same.

  Further, four through holes 249 having a predetermined size (for example, a diameter of 3.5 mm) are formed in the yoke connecting portion 240 at positions of 0 °, 90 °, 180 °, and 270 ° in the drawing. Any of the through holes 249 is formed in the soft magnetic part 252. Further, when the first and second yoke portions 220a and 220b are fitted into the opening of the yoke connecting portion 240, the through holes 229, 249, and 229 are respectively positioned at 0 °, 90 °, 180 °, and 270 °. A set of through-holes is formed by penetrating vertically in a straight line. By fixing the through hole with a bolt (not shown), the components of the magnetic head 210, that is, the first yoke portion 220a, the yoke connecting portion 240, and the second yoke portion 220b are fixed.

  FIG. 20 is a table showing the relationship between the combinations of materials used for the soft magnetic parts 232 and 252 and the nonmagnetic parts 231 and 251 and the output sensitivity. Here, three types of combinations 1 to 3 are illustrated.

  In the combination 1, the soft magnetic parts 232 and 252 are temporary molded bodies obtained by press molding a mixed powder of iron powder and a binder at a low pressure. The nonmagnetic parts 231 and 521 are temporary molded bodies obtained by press molding a mixed powder of brass powder and binder at a low pressure. These two types of temporary formed bodies are combined and press-molded at a high pressure to form first and second yoke portions 220a and 220b and a yoke connection portion 240.

  In the combination 2, the soft magnetic portions 232 and 252 are sintered bodies (ferrite cores) obtained by molding and sintering ferrite powder. The nonmagnetic portions 231 and 521 are green compacts obtained by press-molding a mixed powder of brass powder and binder. Then, the soft magnetic sintered body and the nonmagnetic green compact are assembled with an adhesive to form the first and second yoke portions 220a and 220b and the yoke connecting portion 240.

  In the combination 3, the soft magnetic parts 232 and 252 are green compacts obtained by press-molding a mixed powder of iron powder and binder. The nonmagnetic portions 231 and 521 are green compacts obtained by press-molding a mixed powder of brass powder and binder. Then, the soft magnetic sintered body and the nonmagnetic green compact are assembled with an adhesive to form the first and second yoke portions 220a and 220b and the yoke connecting portion 240.

  In any of the combinations 1 to 3, good sensitivity was obtained at the time of torque detection, but the best sensitivity was obtained particularly when the material of the combination 2 was used. In any combination, the direction of pressing during molding is the same as the direction of the rotation axis when the components are assembled.

  Next, the assembly procedure of the measurement unit 200 will be briefly described. The perspective view of FIG. 21 is a diagram showing a state in which the first yoke portion 220a and the yoke connecting portion 240 are fitted. As shown in FIG. 21A, the yoke connecting portion 240 is fitted on the first yoke portion 220a so as to be placed from above. FIG. 21B is a diagram (plan view) of the state in which the first yoke portion 220a and the yoke connecting portion 240 are fitted as seen from above. At this time, the vicinity of the outer peripheral side of the first soft magnetic part 232a1 of the first yoke part 220a and the vicinity of one end of the first soft magnetic part 252a of the yoke connecting part 240 are connected at a position of 90 °. . Further, at a position rotated by 180 °, that is, at a position of 270 °, the vicinity of the outer peripheral side of the second soft magnetic portion 232a2 of the first yoke portion 220a and the second soft magnetic portion 252b of the yoke connecting portion 240. One end is connected to the vicinity.

  Next, the inner peripheral bobbin 213 is disposed in the internal space formed by fitting the first yoke part 220a and the yoke connecting part 240 together. Further, the second yoke part 220b having the same shape as the first yoke part 220a is fitted so as to cover the yoke connecting part 240 fitted to the first yoke part 220a. At this time, the first soft magnetic portions 232a1, 232a2 of the first yoke portion 220a are linearly oriented so that the linear orientations of the soft magnetic portions 232b1, 232b2 of the second yoke portion 220b are orthogonal to each other. Two yoke portions 220b are arranged. Thus, the soft magnetic part 232 in the vicinity of the outer peripheral side of the second yoke part 220a is connected to the vicinity of the end part on the opposite side of the connection part of the soft magnetic part 252 of the yoke connecting part 240 to the first yoke part 220. As a result, the magnetic head 210 shown in FIG. 17 is completed. Although not shown, a predetermined hole for pulling out the coil wound around the inner bobbin 213 to the outside of the magnetic head 210 is, for example, a joint between the second yoke portion 220b and the yoke connecting portion 240. Provided in the part.

  Further, as shown in FIGS. 13 and 16, the outer peripheral bobbin 211 is fitted on the outer periphery of the yoke connecting portion 240. Thereby, the measurement unit 200 is completed.

  FIG. 22 is a diagram (plan view) in which the soft magnetic portions 232 and 252 in the magnetic head 210 are highlighted. As shown in the figure, two magnetic cores (271, 272) are formed. More specifically, the first magnetic core 271 is formed in the lower right portion of the figure in the magnetic head 210, and the first soft magnetic portion 252a of the yoke connecting portion 240 is a plate-like shape shown in the basic technique. It corresponds to the back yoke portion 31. The first soft magnetic portion 232a1 of the first yoke portion 220a extends in the horizontal left direction, that is, toward the shaft hole 228 from the vicinity of the upper right end portion (90 ° position) of the first soft magnetic portion 252a. Similarly, the second soft magnetic portion 232b2 extends vertically upward from the vicinity of the left lower end portion (180 ° position) of the first soft magnetic portion 252a. These two soft magnetic parts (232a1, 232b2) correspond to the two leg-like yoke parts 32 shown in the basic technique.

  Similarly, the second magnetic core 272 is formed in the upper left part of the figure in the magnetic head 210, and the second soft magnetic part 252b of the yoke connecting part 240 is the plate-like back yoke part 31 shown in the basic technique. It corresponds to. The second soft magnetic portion 232b1 extends from the vicinity of the upper right end portion of the second soft magnetic portion 252b in the vertically downward direction. Similarly, the soft magnetic portion 232a2 extends in the horizontal right direction from the vicinity of the lower left end portion of the second soft magnetic portion 252b. As described above, these two soft magnetic portions (232a2, 232b1) correspond to the leg-shaped yoke portion 32 shown in the basic technique.

  According to the measurement unit 200 including the magnetic head 210 as described above, the magnetic flux 96 as shown in FIG. 4 can be generated, and the magnetic flux 96 can be detected appropriately.

  As mentioned above, according to 1st Embodiment, it is set as the structure which attaches the bobbin by which the inner peripheral coil was wound, and the bobbin by which the outer periphery coil was wound to the inside and outer peripheral part of a cylindrical-shaped magnetic head, respectively. The work of incorporating the inner and outer peripheral coils becomes easy. Moreover, the mounting property of the magnetic core is improved by having a ring shape in which the nonmagnetic portions and the soft magnetic portions are alternately connected. That is, handling becomes easy, and an operation for making the accuracy of the gap length between the surface of the rotating shaft and the magnetic pole appropriate becomes easy. Further, a stable output signal can be obtained by a plurality of magnetic cores arranged in the circumferential direction of the rotation axis. More specifically, the zero point fluctuation is improved, and the shaft shake countermeasure becomes easy.

  By the way, in the magnetic head 210 having the above configuration, two coils of an inner coil for excitation and an outer coil for excitation are used for excitation, and two coils, an inner coil for detection and an outer coil for detection, are used for detection. Is preferably used. Here, since several combinations of excitation coils and detection coils can be assumed, a torque detection experiment was performed and characteristics were confirmed. The results will be described below.

  FIG. 23 is a table showing the results of a torque sensor performance experiment. Here, ten types of Examples 1 to 6 and Comparative Examples 1 to 4 were examined by experiments. In this experiment, the performance of three items of “detection of torque direction”, “sensitivity” of detection, and “suppression of zero point fluctuation” was confirmed. In the figure, “◯” indicates that “performance is good”, “△” indicates that the level is “detectable” or “realizable”, and “×” indicates “not detectable” or It shows that it is “not feasible”.

  Examples 1 to 4 are modes in which two coils, an inner coil for excitation and an outer coil for excitation, are used, and two coils, an inner coil for detection and an outer coil for detection, are used for detection. The difference between the embodiments is the number of magnetic cores. The number of magnetic cores is four in the first embodiment, three in the second embodiment, two in the third embodiment, and one in the fourth embodiment. Both the excitation coil and the detection coil have a pair of inner and outer coils. As a result, as described in the basic technology, the magnetic flux passing around the magnetic core and the rotating shaft is canceled, and the magnetic flux generated by the coil is concentrated on the magnetic path of the magnetic core and the rotating shaft. As a result, the magnetic efficiency is higher than in Examples 5 and 6 described later, and the torque detection sensitivity is improved.

  Example 1 is the same as the aspect shown in the basic technology, and has four magnetic cores. A magnetic head having four magnetic cores will be described later in a second embodiment. The second embodiment has a magnetic head having three magnetic cores, and the third embodiment has two magnetic cores. The configuration of the measurement unit and the magnetic flux generated in the magnetic core can be described as a representative in FIGS. 3 and 5 described above.

  In the first to third embodiments, the influence of the non-uniformity of the magnetic characteristic distribution of the rotating shaft is improved, and the improvement effect is higher in the order of the first, second, and third embodiments as the number of magnetic cores increases. In particular, in Example 1, the influence of the non-uniformity of the magnetic characteristic distribution of the rotating shaft was almost eliminated. In the fourth embodiment, since the magnetic core 30 has only one configuration, the influence of the nonuniformity of the magnetic characteristic distribution of the rotating shaft 90 is not improved, and the zero point fluctuation cannot be suppressed. Further, the torque detection sensitivity is in a practical range, but has not reached a satisfactory level.

  As shown in FIG. 24, the fifth embodiment is a measurement unit 10 having a configuration in which the detection coil in the first embodiment is only the inner coil 81 for detection. Here, the same reference numerals as in FIG. 5 are given, and the same applies to Examples and Comparative Examples described below. When the measurement unit 10 having this configuration is employed, the exciting inner peripheral coil 71 and the exciting outer peripheral coil 72 are paired as an exciting coil, and thus the generated magnetic flux 96 is the same as that of the first embodiment. become. Therefore, the magnetic flux interlinking with the detection inner peripheral coil 81 is the same as in the first embodiment. As a result, good results can be obtained with respect to detection of torque direction, detection sensitivity, and suppression of zero point fluctuation. However, as described above, it is susceptible to magnetic noise.

In the sixth embodiment, as shown in FIG. 25, the measurement unit 10 has a configuration in which the excitation coil in the first embodiment is only the inner coil 71 for excitation. When the measurement unit 10 having this configuration is employed, the magnetic flux linked to the detection inner peripheral coil 81 is a magnetic flux (96 m + 97 m). The magnetic flux interlinking with the detection outer coil 82 is a magnetic flux of 97 m. The voltage induced by the magnetic flux 96m is expressed as V96m, the voltage induced by the magnetic flux 97m is expressed as V97m, and the same applies to the following description. Then, the voltage V81 induced by the magnetic flux interlinking with the detection inner peripheral coil 81 is V81 = V96m + V97m. Hereinafter, this voltage V81 is referred to as “inner coil induction voltage V81”. On the other hand, the voltage V82 induced by the magnetic flux interlinking with the detection outer coil 82 is V82 = V97m. Hereinafter, this voltage V82 is referred to as “outer coil induction voltage V82”. The detection inner peripheral coil 81 and the detection outer peripheral coil 82 are arranged so that the directions of the detection currents are opposite to each other. Therefore, the voltage V _O induced by the magnetic flux linkage in the detection outer peripheral coil 82 and inner coil 81 for detection connected in series is a difference between the inner peripheral coil induced voltage V82 and the inner peripheral coil induced voltage V81. Therefore, the voltage _VO is given by the following equation:
V _O = V81−V82 = (V96m + V97m) −V97m = V96m
It becomes.

  As described above, the magnetic flux 97 that forms the magnetic path on the outer periphery of the magnetic core 30 is not canceled out, and the magnetic flux cannot be efficiently concentrated on the magnetic core 30. Therefore, the detection sensitivity is lower than that in Example 1. Note that the influence of the magnetic flux 97 on the induced voltage between the detection inner peripheral coil 81 and the detection outer peripheral coil 82 can be reduced by appropriately combining the detection inner peripheral coil 81 and the detection outer peripheral coil 82 with each other. Can be offset. Further, an induced voltage corresponding to the magnetic flux 96m of the magnetic core 30 is obtained, and similarly to the graph shown in FIG. 10C, the magnetic flux becomes an asymmetrical curve depending on the direction of the torque, and the direction of the torque can be detected.

  In Comparative Example 1, although not shown, the detection unit in Example 1 is configured as the measurement unit 10 having only the detection outer coil 82. In this configuration, the magnetic flux of the magnetic core 30 does not interlink with the detection outer coil 82, and as a result, torque cannot be detected.

In Comparative Example 2, as shown in FIG. 26, the measurement unit 10 is configured such that the excitation coil in Example 1 is only the excitation outer coil 72. Again, the same components as those in FIG. 4 are denoted by the same reference numerals. When the measurement unit 10 having this configuration is employed, the magnetic flux interlinking with the detection inner peripheral coil 81 becomes the magnetic flux 97n. The magnetic flux interlinking with the detection outer coil 82 is a magnetic flux (96n + 97n). The voltage V81 induced by the magnetic flux interlinked with the detection inner peripheral coil 81 is V81 = V97n, and the voltage V82 induced by the magnetic flux interlinked with the detection outer peripheral coil 82 is V82 = (V96n + V97n). . Hereinafter, this voltage V82 is referred to as “outer coil induction voltage V82”. The detection inner peripheral coil 81 and the detection outer peripheral coil 82 are arranged so that the directions of the detection currents are opposite to each other. Therefore, the voltage V _O induced by the magnetic flux linkage in the detection outer peripheral coil 82 and inner coil 81 for detection connected in series is a difference between the inner peripheral coil induced voltage V82 and the inner peripheral coil induced voltage V81. Therefore, the voltage _VO is given by the following equation:
V _O = V81−V82 = V97n− (V96n + V97n) = − V96n
It becomes.

  As described above, the magnetic flux 97n forming the magnetic path on the outer periphery of the magnetic core 30 is not canceled out, and the magnetic flux cannot be efficiently concentrated on the magnetic core 30. Therefore, the detection sensitivity is lower than that in Example 1. Note that the influence of the magnetic flux 97 on the induced voltage between the detection inner peripheral coil 81 and the detection outer peripheral coil 82 can be reduced by appropriately combining the detection inner peripheral coil 81 and the detection outer peripheral coil 82 with each other. Can be offset. Further, the magnetic flux 96 n passing through the magnetic core 30 wraps around the magnetic core 30 between the two leg-like yoke portions 32 of the magnetic core 30 while hardly passing through the rotating shaft 90. Therefore, the magnetic flux component corresponding to the magnetic permeability change of the rotating shaft 90 is hardly included. Therefore, although the induced voltage 96n can be obtained, it is difficult to detect the direction of torque because there is almost no voltage component corresponding to the permeability change of the rotating shaft 90.

  In Comparative Example 3, as shown in FIG. 27, the measurement coil 10 having a configuration in which the excitation coil in Example 1 is only the excitation inner peripheral coil 71 and the detection coil is only the detection inner peripheral coil 81. It has become. Since the magnetic flux generated by the excitation inner peripheral coil 71 is the same as the magnetic fluxes 96 m and 97 m described in FIG. 6, the magnetic flux interlinked with the detection inner peripheral coil 81 is a magnetic flux (96 m + 97 m). Therefore, the voltage V81 induced by the magnetic flux interlinking with the detection inner peripheral coil 81 is V81 = V96m + V97m.

  As described above, the magnetic flux 97m that forms a magnetic path on the outer periphery of the magnetic core 30 is not offset, and the magnetic flux cannot be efficiently concentrated on the magnetic core 30. Therefore, the detection sensitivity is lower than that in Example 1. In addition, the influence of the magnetic flux 97m on the induced voltage of the detection inner peripheral coil 81 cannot be canceled by the detection inner peripheral coil 81 alone. Therefore, it is difficult to detect the direction of torque.

  In the comparative example 4, as shown in FIG. 28, the exciting coil 98 a and the detecting coil 98 b are provided in the leg-shaped yoke portion 32 of the magnetic core 30. In the case of the measurement unit 10 having this configuration, since a coil is wound for each magnetic core 30, the number of man-hours increases and the cost increases. In addition, the number of coil parts increases. Furthermore, due to the magnetic non-uniformity of the rotating shaft 90, the output detected for each magnetic core varies, making it very difficult to suppress the zero point fluctuation.

(Second Embodiment)
In this embodiment, a magnetic head and a measurement unit having four magnetic cores will be described. The difference from the first embodiment is the number and position of formation of the nonmagnetic portion and the soft magnetic portion. The differences are mainly described, and the common portions are denoted by the reference numerals in the description and the drawings. Omitted.

  29A and 29B are a three-side view and a cross-sectional view of the measurement unit 300. FIG. 29A is a plan view, FIG. 29B is a front view (left half), a cross-sectional view (right half), and FIG. Shows a bottom view. Similar to the first embodiment, the measurement unit 300 includes a cylindrical magnetic head 310, an outer peripheral bobbin 311 attached to the outside of the magnetic head 310, and an inner peripheral bobbin 313 provided inside the magnetic head 310. Is done.

  Further, the magnetic head 310 includes three elements, ie, an annular first yoke portion 320a and second yoke portion 320b, and a cylindrical yoke connecting portion 340. The first yoke part 320a and the second yoke part 320b have the same shape, and fit into the two openings of the yoke connection part 340.

  30A and 30B are a three-side view and a cross-sectional view of the first yoke portion 320a. FIG. 30A is a plan view, FIG. 30B is a front view (left half), a cross-sectional view (right half), and FIG. c) shows a bottom view. As in the first embodiment, the first yoke portion 320a has a shape in which three large, medium, and small rings are concentrically overlapped. Eight through-holes 329 are formed in the outer peripheral connection portion 321 that is a ring-shaped portion formed on the outermost side at 45 ° intervals from the 0 ° position.

  The soft magnetic part of the first yoke part 320a is formed at a diameter position with a predetermined width d21. Specifically, the first to fourth soft magnetic portions 332a1 to 332a4 (hereinafter simply referred to as “soft magnetic portion 332a” when the first to fourth soft magnetic portions 332a1 to 332a4 are not distinguished) are 0. It is formed at intervals of 90 ° in the circumferential direction from the position of °. In addition, a nonmagnetic part 331a is formed between the soft magnetic parts 332a, and the first to fourth soft magnetic parts 332a1 to 332a4 are separated.

  31A and 31B are a three-side view and a cross-sectional view of the yoke connecting portion 340. FIG. 31A is a plan view, FIG. 31B is a front view (left half), a cross-sectional view (right half), and FIG. ) Shows a bottom view.

  The yoke connecting portion 340 has a ring shape when viewed from above, and four soft magnetic portions and four nonmagnetic portions 351 are alternately arranged at intervals slightly shifted from 45 ° in the rotation axis direction. Specifically, the first soft magnetic part 352a1 is formed from a position of 0 ° to a position of 45 ° in the drawing. The second soft magnetic portion 352a2 is formed from the 90 ° position to the 135 ° position in the drawing. The third soft magnetic part 352a3 is formed from a position of 180 ° to a position of 225 ° in this drawing. The fourth soft magnetic part 352a4 is formed from a position of 270 ° to a position of 315 ° in this drawing. Note that both end portions of each of the soft magnetic portions 352a1 to 352a are connected to the soft magnetic portion 332a of the first yoke portion 320a and the soft magnetic portion 332b of the second yoke portion 320b in order to have a predetermined width d31, specifically Is larger by 1/2 of the width d21 of the soft magnetic part 332a of the first yoke part 320. Eight through holes 349 are formed at intervals of 45 ° in the circumferential direction from the 0 ° position.

The first and second yoke portions 320a and 320b and the yoke connecting portion 340 are assembled to form the magnetic head 310. At this time, the first soft magnetic portions 332a1 and 332b1 of the first and second yoke portions 320a and 320b are shifted by 45 ° and fitted in the vicinity of both ends of the first soft magnetic portion 352a1 of the yoke connection portion 340. 1 magnetic core 371 is formed. Similarly, the second to fourth soft magnetic portions 332a2 to 332a4 and 332b2 to 332b4 of the first and second yoke portions 320a and 320b are adjacent to both ends of the second to fourth soft magnetic portions 352a1 of the yoke connecting portion 340. To the second to fourth magnetic cores 372 to 374, respectively. As a result, the first to fourth magnetic cores 371 to 374 are formed at equal intervals in the magnetic head 310. At this time, the first and second yoke portions 320a and 320b and the through holes 329 and 349 provided in the yoke connecting portion 340 are connected in the vertical direction to form a pair of through holes. Eight sets of these through holes are formed, and the magnetic head 310 can be easily assembled appropriately by fastening these eight sets of through holes with bolts. When the outer peripheral bobbin 311 is attached to the magnetic head 310, the measurement unit 300 shown in FIG. 29 is completed. The measurement unit 300 including the magnetic head 310 having this configuration has the same configuration as that shown in the basic technique of FIGS.

  As mentioned above, according to 2nd Embodiment, the effect shown in Example 1 in 1st Embodiment is acquired.

(Third embodiment)
In the third embodiment, as shown in FIG. 32, a cylindrical bias yoke 410 is added based on the measurement unit 300 shown in the second embodiment. Here, the measurement unit 300 shown in the second embodiment is referred to as an internal measurement unit 300a for convenience. A cylindrical bias yoke 410 has a configuration in which an internal measurement unit 300a is disposed via first and second spacers 446a and 446b, and this configuration is hereinafter referred to as a bias added measurement unit 400. FIG. 32 shows a longitudinal cross-sectional view of the bias added measurement unit 400, and the right half represents a portion that becomes a magnetic path by hatching. Note that the internal measurement unit 300a has the same structure as that shown in the second embodiment, and therefore description and reference numerals thereof are omitted.

  On the upper surface of the internal measurement unit 300a, an annular first spacer 446a having the same shape as the upper surface and having a shaft hole 429a into which the rotation shaft is inserted at the center is disposed. Further, an annular second spacer 446b having the same shape as the lower surface and having a shaft hole 429b into which the rotation shaft is inserted at the center is disposed on the lower surface of the internal measurement unit 300a. The shaft hole 429b has the same size as the diameter of the shaft hole formed in the center of the internal measurement unit 300a.

  The first and second spacers 446a and 446b are provided with eight through holes 445 at the same positions as the fixing through holes 445 provided in the internal measurement unit 300a. The first and second spacers 446a and 446b are formed of a material that can magnetically separate the biased measurement unit 400 and the internal measurement unit 300a, and prevent magnetic interference.

  The bias yoke 410 includes a lower yoke end portion 448b in which an annular bottom surface and a cylindrical side surface are integrated, and a ring-shaped magnet 447 (hereinafter referred to as “the upper side surface of the lower yoke end portion 448b”). Ring magnet 447 ") and an annular upper yoke end 448a disposed on the upper side of the ring magnet 447. The ring magnet 447 is a permanent magnet. For example, the side in contact with the lower yoke end 448b is magnetized to the S pole, and the side in contact with the upper yoke end 448a is magnetized to the N pole.

  The lower yoke end 448b has a shaft hole 428b into which the rotating shaft 90 is inserted at the center of the annular bottom surface, and a shaft hole 428a into which the rotating shaft 90 is inserted at the center of the upper yoke end 448a. Is formed. Similar to the first and second spacers 446a and 446b, the shaft holes 428a and 428b have the same size as the diameter of the shaft hole 328 formed at the center of the internal measurement unit 300a. Further, eight through holes 445 are provided in the annular surfaces of the lower yoke end portion 448b and the upper yoke end portion 448a, respectively. The through hole 445 is formed at the positions of the internal measurement unit 300a and the first and second spacers 446a and 446b in a state where the shaft holes 428a and 428b of the bias yoke 410 and the shaft hole 329 of the internal measurement unit 300a are aligned. It is the same position as the provided through hole 445 for fixing. That is, eight through holes 445 are formed at intervals of 45 ° in the circumferential direction from the 0 ° position.

  Accordingly, the through hole 329 of the internal measurement unit 300a, the through hole 445 of the bias yoke 410, and the through holes 445 of the first and second spacers 446a and 446b are vertically connected to form a pair of through holes 445, which are connected vertically. By fastening the through hole 445 with a bolt, the bias added measurement unit 400 can be assembled easily and appropriately.

  As described above, by adding the ring-shaped bias yoke 410 having the ring magnet 447 to the internal measurement unit 300a, the bias magnetic flux is uniformly distributed in the circumferential direction. As a result, the magnetic noise is reduced. The influence can be eliminated and the torque detection accuracy is improved.

(Fourth embodiment)
In the fourth embodiment, as in the third embodiment, a cylindrical bias yoke 510 is added based on the measurement unit 300 as shown in FIG. The difference is that in the bias yoke 510, the position where the ring magnet 557 is provided, and further, two bias coils are provided, and two spacers 556a, 556b provided so as to sandwich the internal measurement unit 300a, The positions of the through holes 555 are the same. Hereinafter, different points will be mainly described. FIG. 33 shows a vertical cross-sectional view of the bias added measurement unit 500, and the right half represents a portion that becomes a magnetic path by hatching.

  The bias yoke 510 includes a cylindrical bias yoke connection portion 558b, an annular upper yoke end portion 558a that fits in the opening of the bias yoke connection portion 558b, and an opening on the lower side of the bias yoke connection portion 558b in the figure. An annular lower yoke end portion 558c to be fitted, and a fixing plate 556c provided under the lower yoke end portion 558c. In addition, a shaft hole 526a into which the rotation shaft is inserted is provided at the center portion of the lower yoke end portion 558c, and a ring magnet 557 is fitted into the shaft hole 526a. An opening 528 having a predetermined size is formed in the center portion of the ring magnet 557. The ring magnet 557 is sandwiched and supported by two members, the second spacer 556b and the fixed plate 556c.

  A bias inner peripheral coil 559a wound around a bobbin is attached to the inner peripheral surface of the yoke connecting portion 558b. Bias inner peripheral coil 559a is in contact with the upper surface of lower yoke end 558c. A biasing outer coil 559b is attached to the outer peripheral surface of the yoke connecting portion 558b. The bias inner peripheral coil 559a and the bias outer peripheral coil 559b are arranged at positions facing each other with the yoke connecting portion 558b interposed therebetween.

  With the configuration as described above, the bias magnetic flux is uniformly distributed in the circumferential direction. As a result, the influence of magnetic noise can be eliminated, and the torque detection accuracy is improved. In addition, the amount of bias magnetic flux can be easily adjusted by changing the amount of current flowing through the bias inner peripheral coil 559a and the bias outer peripheral coil 559b. Further, by using the ring magnet 557 and the bias coil together, power consumption can be suppressed as compared with the case where the bias magnetic flux is generated only by the coil. However, the portion where the ring magnet 557 is fitted to the magnetic flux generated by the bias coil acts as a magnetic gap, and there is a risk that magnetic flux leakage will occur. Further, the bias coil may be configured by only the bias inner peripheral coil 559a.

(Fifth embodiment)
In the fifth embodiment, as shown in FIG. 34, the number of bias coils in the fourth embodiment is one, and the position where the coils are further provided is the upper side of the upper yoke end 658a. The position of the ring magnet 657, the positions of the two spacers 656a, 656b, 656c and the through hole 655 provided so as to sandwich the internal measurement unit 300a are the same as those in the fourth embodiment. Hereinafter, different points will be described. FIG. 34 shows a vertical cross-sectional view of the bias added measurement unit 600, and the right half shows a portion that becomes a magnetic path by hatching.

  A cylindrical member 690 having a bias coil 669 wound around a bobbin is attached to the upper surface of the upper yoke connecting portion 658a. Specifically, a cylindrical third spacer 668b having upper and lower openings, an annular fixing plate 668a that closes the upper opening of the third spacer 668b, and an annular second opening that closes the lower opening of the third spacer 668b. 4 spacers 668c. The fourth spacer 668c magnetically separates the coil 669 from the upper yoke end 658a. A shaft hole for inserting the rotation shaft 90 is formed at the center of the ring of the fixed plate 668a and the fourth spacer 668c. These shaft holes have the same diameter as the central shaft hole of the internal measurement unit 300a. Further, a through hole 655 is formed in the cylindrical member 690, and the through holes of the internal measurement unit 300a, the bias yoke member 610, and the cylindrical member 690 are connected to form a set of through holes. Accordingly, the internal measurement unit 300a, the bias yoke member 610, and the cylindrical member 690 can be fixed together.

  With the above configuration, the amount of bias magnetic flux can be easily adjusted by changing the amount of current flowing through the bias coil 669. Further, by using the ring magnet 657 and the bias coil together, power consumption can be suppressed as compared with the case where the bias magnetic flux is generated only by the coil.

  Note that a ring magnet 657 and a bias coil 669 may be provided on both the upper yoke end 658a and the lower yoke end 658c.

  The present invention can be widely used for torque sensors that use magnetostriction characteristics.

It is a perspective view of the magnetic core in basic technology. It is a side view of the magnetic core in basic technology. It is the front view seen from the direction perpendicular | vertical to the axial direction of the rotating shaft of a torque sensor in basic technology. It is the front view seen from the axial direction of the rotating shaft of a torque sensor in basic technology. It is a figure showing the magnetic core located in the upper and lower sides of a rotating shaft in order to explain induction of a magnetic field in basic technology. It is a figure explaining induction | guidance | derivation of the magnetic field by the inner peripheral coil for excitation in a basic technique. It is a figure explaining the induction | guidance | derivation of the magnetic field by the outer periphery coil for excitation in basic technology. It is the figure which showed the torque and stress applied to a magnetic core in a basic technique. It is the figure which showed the relationship between the strength of the magnetic field applied to a rotating shaft, and the magnetic flux density in a rotating shaft in basic technology. It is the figure which showed the relationship between the torque applied to a rotating shaft, and the magnetic flux (linkage magnetic flux) detected by the coil for a detection in basic technology. It is the figure which showed the circuit connection which has connected the inner periphery coil for excitation of the torque sensor, and the outer periphery coil for excitation in a basic technique in series. It is the figure which showed the circuit connection which has connected the inner periphery coil for excitation of the torque sensor, and the outer periphery coil for excitation in a basic technique in parallel. It is the figure which showed the relationship between the applied torque, 1st output, 2nd output, and final output in a basic technique. It is the perspective view which showed the external appearance of the measurement unit based on 1st Embodiment. It is the perspective view shown in the state which decomposed | disassembled the measurement unit based on 1st Embodiment into the component. It is the 3rd page figure and sectional drawing of a measurement unit based on 1st Embodiment. It is the perspective view which showed the external appearance of the magnetic head of the state which removed the outer peripheral bobbin and the inner peripheral bobbin based on 1st Embodiment. It is a three-view figure and sectional view of the 1st yoke part concerning a 1st embodiment. It is a three-view figure and sectional view of a yoke connection part concerning a 1st embodiment. It is the table | surface which showed the relationship of the combination of the material used for a soft magnetic part and a nonmagnetic part, and output sensitivity based on 1st Embodiment. It is the figure which showed the state which the 1st yoke part based on 1st Embodiment and the yoke connection part fitted. It is the figure (plan view) which emphasized and showed the soft-magnetic part in the magnetic head based on 1st Embodiment. It is a table | surface which shows the result of having performed the performance experiment of the torque sensor based on 1st Embodiment. FIG. 10 is a schematic diagram illustrating a configuration of a measurement unit according to Example 5. FIG. 10 is a schematic diagram illustrating a configuration of a measurement unit according to Example 6. 10 is a schematic diagram illustrating a configuration of a measurement unit according to Comparative Example 2. FIG. It is the schematic which shows the structure of the measurement unit based on the comparative example 3. It is the schematic which shows the structure of the measurement unit based on the comparative example 4. It is a three-view figure of the measurement unit based on 2nd Embodiment. It is a three-view figure of the yoke part based on 2nd Embodiment. It is a three-view figure of the yoke connection part based on 2nd Embodiment. It is a block diagram of the bias addition measurement unit of a torque sensor based on 3rd Embodiment. It is a block diagram of the bias addition measurement unit of a torque sensor based on 4th Embodiment. It is a block diagram of the bias addition measurement unit of the torque sensor based on 5th Embodiment. It is the schematic which shows the structure of the magnetostrictive torque sensor based on a prior art.

Explanation of symbols

30, 40, 50, 60, 130, 140, 150, 160, 271, 272, 371-374 Magnetic core 31, 41, 51, 61 Plate-shaped back yoke part 32, 42, 132, 142, 152, 162 Leg shape Yoke part 71, 171, 214a Excitation inner peripheral coil 72, 172, 212a Excitation outer peripheral coil 81, 181, 214b Detection inner peripheral coil 82, 182, 212b Detection outer peripheral coil 90 Rotating shaft 92 Inner peripheral surface 99a Synchronous detection Circuit 200, 300 Measuring unit 210, 310 Magnetic head 211, 311 Outer bobbin 213, 313 Inner bobbin 220a, 320a First yoke part 220b, 320b Second yoke part 221, 321 Outer connection part 222 Bobbin housing part 228, 428a, 428b, 429a, 429b Shaft holes 229, 249, 32 9, 349, 555 Through-hole 231a, 231b, 251, 331a, 331b Non-magnetic part 232, 232a1, 232a2, 232b1, 232b2, 252a, 252b, 332a, 352a1-352a4 Soft magnetic part 240, 340 Yoke connection part 300a Internal measurement Unit 400, 500 Bias added measurement unit 446a, 556a, 656a First spacer 446b, 556b, 656b Second spacer 447 Ring magnet 448a Upper yoke end 556c Fixed plate 557 Ring magnet 558a Upper yoke end 558b Bias yoke connection 559a Bias inner peripheral coil 559b Bias outer peripheral coil 600 Bias added measurement unit 656a, 656b Spacer 658a Upper yoke end 658c Lower yoke end 668a Fixed plate 68b third spacer 668c fourth spacers 669 bias coil

Claims (17)

A magnetic core unit used for a torque sensor,
A cylindrical yoke connecting portion in which nonmagnetic portions and soft magnetic portions are alternately arranged in the circumferential direction;
A substantially annular yoke portion, which is attached to both ends of the yoke connecting portion and in which nonmagnetic portions and soft magnetic portions are alternately arranged in the circumferential direction,
A magnetic core unit comprising a set of magnetic cores composed of the soft magnetic part of the yoke connecting part and the soft magnetic part of the yoke part.   2. The yoke portion is provided with a shaft hole at a center thereof, and the soft magnetic portion extends linearly from a side surface of the shaft hole toward a radially outer side of the yoke connection portion. The magnetic core unit described in 1.   3. The yoke connecting portion according to claim 1, wherein the soft magnetic portion is in contact with the soft magnetic portion of the yoke portion in a state where the yoke portion is attached to an end portion. The magnetic core unit described.   The soft magnetic part of the yoke connecting part and the soft magnetic part of the yoke part constitute a set of magnetic cores with the yoke part attached to the end of the yoke connecting part; The magnetic core unit according to any one of claims 1 to 3.   5. The magnetic core unit according to claim 1, wherein the two yoke portions attached to both ends of the yoke connecting portion have the same shape.   The magnetic core unit according to claim 1, wherein the yoke portion is fitted to an end portion of the yoke connecting portion. With the yoke part attached to the end of the yoke connection part,
The magnetism according to any one of claims 2 to 6, wherein a line connecting the centers of the end surfaces of the two yoke portions on the shaft hole side forms a predetermined angle with the axial direction of the shaft hole. Core unit.   The magnetic core unit according to claim 7, wherein the predetermined angle is set to approximately 45 °.   The magnetic core unit according to claim 1, wherein a plurality of the magnetic cores are provided magnetically separated.   The magnetic core unit according to any one of claims 1 to 9, wherein the material of the soft magnetic part is Mn-Zn based ferrite. A torque sensor comprising the magnetic core unit according to any one of claims 1 to 10,
An inner circumference coil for excitation and an inner circumference coil for detection on the inner circumference of the yoke connecting portion;
A torque sensor comprising: an outer peripheral coil for excitation and an outer peripheral coil for detection on an outer periphery of the cylindrical yoke connecting portion. A torque sensor comprising the magnetic core unit according to any one of claims 8 to 10,
The first magnetic core unit in which the predetermined angle is set to about + 45 ° and the second magnetic core unit in which the predetermined angle is set to about −45 °. 9. The torque sensor according to 9. A torque sensor comprising the magnetic core unit according to any one of claims 1 to 10,
It has an exterior yoke part made of a material that can form a magnetic path,
The torque sensor according to claim 11 or 12, wherein the exterior yoke portion includes the magnetic core unit magnetically separated from the inside.   The torque sensor according to claim 13, wherein the exterior yoke portion is cylindrical, and has an annular magnet on an outer peripheral portion of the exterior yoke portion. A torque sensor comprising the magnetic core unit according to any one of claims 1 to 10,
The exterior yoke portion includes an annular magnet provided on one end surface of the exterior yoke portion and having the same diameter as the shaft hole of the yoke portion, and a coil disposed on an inner surface of the exterior yoke portion. The torque sensor according to claim 13. A torque sensor comprising the magnetic core unit according to any one of claims 1 to 10,
The torque sensor according to claim 15, further comprising a coil disposed on an inner peripheral surface or an outer surface of the exterior yoke portion. A torque sensor comprising the magnetic core unit according to any one of claims 1 to 10,
An annular magnet provided on one end surface of the exterior yoke portion, having an approximately same diameter as the shaft hole of the yoke portion;
A coil provided on the other end face of the exterior yoke portion in a state of being magnetically separated from the exterior yoke portion;
The torque sensor according to claim 13, wherein

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