JP2022160054A - Rotation angle detector - Google Patents

Abstract

To provide a small size and precise rotation angle detector.SOLUTION: The rotation angle detector includes: a rotor 2 that has a concavo-convex portion 21 in which the diameter of the outer peripheral surface 2fo changes periodically; a bias magnetic field generator 31 facing rotor 2 with a gap, which generates a magnetic field between the concavo-convex portion 21 and itself; and a stationary part 3 that has multiple magnetic flux density detectors 32 for detecting the generated magnetic field, which is placed along an opposing surface 31fc in a circumferential direction Dc. On the outer part in the circumferential direction Dc of the opposing surface 31fc, a protruding portion 31p protruding in the radial direction so as to be closer to rotating shaft 22 than the portion where magnetic flux density detector 32 located at the end is arranged.SELECTED DRAWING: Figure 1

Description

The present application relates to a rotation angle detection device.

A stator having a bias magnetic field generating section extending in the circumferential direction and a plurality of magnetic flux density detecting sections arranged along the circumferential direction are arranged opposite to the outer peripheral surface of the rotor whose diameter changes along the circumferential direction. A rotation angle detection device is known that detects a rotation angle from a change in . At that time, a rotation angle detection device is disclosed that improves detection accuracy without increasing the weight by defining the installation range in the circumferential direction of the bias magnetic field generation unit and the magnetic material provided on the back side thereof (for example, , see Patent Document 1).

JP 2019-109053 A (paragraphs 0009 to 0020, FIGS. 1 to 3)

However, in the magnetic sensor described above, disturbance of the magnetic flux density vector occurs at the circumferential end of the bias magnetic field generating portion, and the radial component of the magnetic flux density, which is a signal component, decreases at the magnetic flux density detecting portion at the circumferential end. . As a result, an imbalance occurs in the detected values of the magnetic flux density between the magnetic flux density detecting portions at the circumferential end portions and the circumferential central portion, resulting in a problem of degraded angle detection accuracy.

The present application discloses a technique for solving the above problems, and an object of the present application is to obtain a compact and accurate rotation angle detection device.

A rotation angle detection device disclosed in the present application includes: a rotor having irregularities made of a magnetic material whose outer peripheral surface diameter periodically changes and supported so as to be rotatable about a rotation shaft; A bias magnetic field generating section that faces a part of the outer peripheral surface in the circumferential direction with a gap therebetween and generates a magnetic field between itself and the uneven portion; A stator having a plurality of magnetic flux density detection units that are arranged along the circumferential direction and detect the generated magnetic field, and from a portion of the facing surface where the plurality of magnetic flux density detection units are arranged in the circumferential direction At the outermost portion, a protrusion that protrudes in the radial direction so as to be closer to the rotating shaft than the portion where the magnetic flux density detecting portion located at the end in the circumferential direction is arranged among the plurality of magnetic flux density detecting portions A part is formed.

According to the rotation angle detection device disclosed in the present application, by reducing the disturbance of the magnetic flux density vector at the ends in the circumferential direction, the imbalance in the detected value of the magnetic flux density in each magnetic flux density detection unit is reduced, and the small and accurate It is possible to obtain an excellent rotation angle detection device.

1 is a schematic diagram showing the overall configuration of a rotation angle detection device according to a first embodiment; FIG. 1 is a functional block diagram for explaining the configuration of a rotation angle detection device according to a first embodiment; FIG. 3A and 3B are partially enlarged schematic diagrams with different magnifications of the rotation angle detection device according to the first embodiment. FIG. 5 is a bar graph format comparing ratios of secondary harmonic components to signal components in the rotation angle detection device according to the first embodiment and the rotation angle detection device according to the comparative example; FIG. 5 is a partially enlarged schematic diagram of a rotation angle detection device according to a modification of the first embodiment; FIG. 11 is a partially enlarged schematic diagram of a rotation angle detection device according to a second comparative example; FIG. 10 is a bar graph format comparing ratios of secondary harmonic components to signal components in rotation angle detection devices according to a comparative example and a second comparative example; 8 is a partially enlarged schematic diagram of the rotation angle detection device according to the second modification of the first embodiment; FIG. FIG. 2 is a block diagram showing a configuration example of a part that executes rotation angle calculation processing of the rotation angle detection device according to the first embodiment; FIG. 8 is a partially enlarged schematic diagram of the rotation angle detection device according to the second embodiment; 11A and 11B are partially enlarged schematic diagrams of a rotation angle detection device according to Embodiment 3 and a rotation angle detection device according to a modification thereof, respectively. FIG. 10 is a bar graph format comparing ratios of secondary harmonic components to signal components in the rotation angle detection device according to the third embodiment and the rotation angle detection device according to the comparative example; FIG. 11 is a partially enlarged schematic diagram of a rotation angle detection device according to a fourth embodiment; 14A and 14B are partially enlarged schematic diagrams of a rotation angle detection device according to Embodiment 5 and a rotation angle detection device according to a modification thereof, respectively. FIG. 11 is a partially enlarged schematic diagram of a rotation angle detection device according to a second modification of the fifth embodiment;

Embodiment 1.
FIGS. 1 to 4 are for explaining the configuration and operation of the rotation angle detection device according to the first embodiment. FIG. 1 shows the overall configuration of the rotation angle detection device. 2 is a schematic diagram showing the connection of signals between a cross-sectional shape showing a positional relationship in a plane direction perpendicular to the axis and a rotation angle calculation processing unit, and FIG. 2 is a functional block diagram showing the connection between a stator and an angle calculation unit. FIG. 3 is an enlarged schematic diagram (FIG. 3A) of the vicinity of the portion where the rotor and the stator of the rotation angle detection device in FIG. (Fig. 3B). FIG. 4 shows signals of three magnetic flux density detection units in each of the rotation angle detection devices of Example 1 and Comparative Example (Comparative Example 1) for explaining the effect of the rotation angle detection device according to Embodiment 1. 4 is a bar graph comparing ratios of secondary harmonic components to components with reference to the signal of the central magnetic flux density detector.

Before describing the characteristic configuration of the present application, the basic configuration of the rotation angle detection device and the calculation of the rotation angle will be described below with reference to the drawings. The rotation angle detection device 1 is directly connected to, for example, a shaft of a rotating electric machine, detects the rotation angle or the number of rotations of the rotating electric machine, and uses it for rotation control, measurement, and the like. As shown in FIG. 1, the rotation angle detection device 1 according to the first embodiment has a rotor 2 that rotates around a rotation shaft 22 as a mechanical configuration, and an outer peripheral surface 2fo of the rotor 2 that is arranged to face the rotor 2. A stator 3 is provided. As a configuration for performing arithmetic processing, an angle calculator 5 is provided for processing the signals output from each of the plurality of magnetic flux density detectors 32 of the stator 3 and calculating the rotation angle.

The rotor 2 has a cylindrical rotating shaft 22 and uneven portions 21 provided radially outwardly of the rotating shaft 22 . The uneven portion 21 is made of a magnetic material, and is formed such that the distance from the center X2 of the rotating shaft 22 periodically and smoothly changes. FIG. 1 shows a case where 24 unevennesses are formed in the unevenness portion 21 and the unevennesses change periodically 24 times while the rotor 2 makes one rotation about the rotating shaft 22 .

The stator 3 is provided on the radially outer side of the rotor 2 so as to face a portion of the uneven portion 21 (outer peripheral surface 2fo) in the circumferential direction Dc, and extends along the circumferential direction Dc. It has a bias magnetic field generator 31 and a plurality of magnetic flux density detectors 32 . The bias magnetic field generating section 31 is installed so as to overlap with the magnetic flux density detecting section 32 radially outward and extend along the circumferential direction Dc. A plurality of magnetic flux density detection units 32 are arranged at equal intervals on an arc equidistant from the center X2 of the rotation shaft 22 so as to face the uneven portion 21 with a gap therebetween. 1 and 2 show the angle calculator 5 and the stator 3 as separate components, the angle calculator 5 may be provided in the stator 3. FIG.

Each of the plurality of magnetic flux density detectors 32 converts the magnetic flux density, which fluctuates substantially sinusoidally in accordance with changes in permeance caused by changes in the air gap between the bias magnetic field generator 31 and the concave-convex portion 21, into an electric signal and outputs the electric signal. The drawing shows a case where three magnetic flux density detection units 32 are arranged at intervals of ⅓ period (120°) of each unevenness of the uneven portion 21 .

In this case, the three magnetic flux density detectors 32 output signal A, signal B, and signal C, which are three substantially sinusoidal signals whose phases are shifted every 1/3 cycle. The angle calculator 5 performs two-phase conversion on the multiple outputs obtained by the magnetic flux density detector 32, and calculates the rotation angle by calculating an arctangent function. For example, in the case of the arrangement described above, the signal A, the signal B, and the signal C, which are the output signals of the magnetic flux density detection unit 32, are two-phase-converted by equation (1), and the rotor 2 is converted by the arctangent function of equation (2). A rotation angle θ can be calculated.

When the number of the magnetic flux density detection units 32 is three, even if a harmonic component having a frequency three times higher than the signal component S of the signal A, the signal B, and the signal C is present, during the two-phase conversion Since they cancel each other out and are removed, they do not affect the final angle calculation result. Therefore, it is possible to provide robustness against the third harmonic component.

Based on the basic configuration described above, the characteristic configuration and operation of the present application will be described. As shown in FIGS. 3A and 3B, at both ends (circumferential direction ends) of the bias magnetic field generating portion 31 in the circumferential direction Dc, a surface 31fc facing the rotor 2 is formed, and a portion where the magnetic flux density detecting portion 32 is arranged. A protruding portion 31p protruding closer to the center X2 of the rotating shaft 22 is provided.

By providing the protruding portion 31p at the circumferential end portion, the region in which the circumferential component, which is the turbulent component of the magnetic flux density, exists around the bias magnetic field generating portion 31 is limited to the circumferential end portion. 31 can generate a uniform magnetic flux density over a wide range in the circumferential direction Dc. As a result, the influence of the disturbance component of the magnetic flux density on the magnetic flux density detection units 32 located at the ends in the circumferential direction is reduced. The imbalance is reduced and the angle detection accuracy can be improved.

Regarding the effect, the characteristics of Example 1 in which the protrusion 31p described with reference to FIG. will be described with reference to FIG. In FIG. 4, the horizontal axis indicates the position of the magnetic flux density detection section that outputs the output signal, and the vertical axis indicates the ratio of the second harmonic component Hs having a double frequency to the signal component S of each magnetic flux density detection section. . However, this is the case where the number of magnetic flux density detection units is three. Signals A and C are the output signals of the magnetic flux density detection units located at the ends in the circumferential direction, and signal B is the output signal of the magnetic flux density detection unit located in the center in the circumferential direction. , and shows the difference value when the signal B is used as a reference.

As shown in FIG. 4, secondary harmonic components (differences from signal B) are generated in signals A and C regardless of the presence or absence of protrusion 31p. The difference is 1.4%, which is 0.5% lower than 1.9% in Example 1, and the difference value is reduced by 26% compared to Comparative Example 1. That is, the existence of the projecting portion 31p at the circumferential end portion of the bias magnetic field generating portion 31 reduces the imbalance of the output signals of the magnetic flux density detecting portions 32. FIG.

Here, the protrusion amount will be described. In FIG. 3B, the protrusion amount Hp from the facing surface 31fc of the protrusion 31p is larger than the height of the facing surface 32fc of the magnetic flux density detection unit 32 facing the rotor 2, and is set to the thickness of the magnetic flux density detection unit 32 or more. explained. By setting the amount of protrusion Hp as described above, the magnetic flux density detection unit 32 is positioned in an area in which the magnetic flux density component parallel to the protrusion direction generated by the protrusion 31p is sufficiently larger than the magnetic flux density component perpendicular to the protrusion direction. become.

As a result, the circumferential component (disturbance component) of the magnetic flux density in the magnetic flux density detection section 32 is reduced, and the radial component (signal component) of the magnetic flux density is increased. As a result, since the second harmonic component Hs with respect to the signal component S becomes smaller, the angle error can be further reduced. Furthermore, since the signal component S itself is increased, the noise resistance is further improved.

The effect of reducing the imbalance of the output signal is that the protrusion amount Hp from the facing surface 31fc of the protrusion 31p is larger than the height of the facing surface 32fc of the magnetic flux density detection unit 32 facing the rotor 2, and ΔH is positive. It is not limited to showing the value of Basically, on the facing surface 31fc of the bias magnetic field generator 31, even if the protruding portion 31p is slightly smaller than the portions where the magnetic flux density detectors 32 are arranged at both ends, it is sufficient if it is closer to the center X2. .

However, when ΔH is a negative value and the protrusion amount Hp of the protruding portion 31p is set to a value smaller than the thickness of the magnetic flux density detecting portion 32, it is desirable to set the protruding amount to be larger than the protruding amount that may occur due to processing accuracy. Specifically, it is desirable to set the amount of protrusion Hp to a value that exceeds the variation in processing accuracy when processing the surface of the opposing surface 31fc into an arc. By doing so, it is possible to obtain a highly reliable rotation angle detection device 1 in which there is no variation in output signal imbalance between products and the reduction effect is stable.

That is, if the protrusion amount Hp is positive, the minimum effect is obtained in reducing the imbalance of the output signals of the magnetic flux densities of the magnetic flux density detectors 32 . However, considering the reliability of the product, it is desirable to set the protrusion amount Hp to at least exceed the variations in processing accuracy and have a significant difference. A more desirable form is to provide the projecting portion 31p so as to be closer to the center X2 (project toward the center X2) than at least the surfaces 32fc of the magnetic flux density detecting portions 32 at both ends facing the rotor 2. good.

Regarding the influence on the detection accuracy, there is no particular restriction on the increase in the protrusion amount Hp. However, since it is necessary to prevent interference with the rotor 2 , it is necessary to suppress contact with the outer peripheral surface 2fo of the rotor 2 . Specifically, considering the machining accuracy and tolerance of each of the rotor 2 and the bias magnetic field generating section 31, and the positioning accuracy between the rotor 2 and the stator 3, the outer peripheral surface 2fo of the rotor 2 and the It is necessary to set the upper limit of the amount of protrusion Hp to a value that ensures a gap of .

The projecting amount Hp of the projecting portion 31p in each of the following embodiments is also provided in such a manner. , a more conspicuous configuration is adopted.

First modification.
In the above example, an example in which the protruding portions are provided at the circumferential ends is shown. In the present first modified example and the following comparative example 2, the arrangement position of the protruding portion will be examined. In this first modified example, an example in which the projecting portion is provided inside the circumferential end portion will be described. FIG. 5 is for explaining the configuration of the rotation angle detection device according to the first modification, and is an enlarged schematic diagram corresponding to FIG. It is a diagram.

In the rotation angle detection device 1 according to the first modification, as shown in FIG. 5, protrusions 31p are provided near the circumferential ends, that is, between the magnetic flux density detectors 32 at both ends and the circumferential ends. Even if the protruding portion 31p is not located at the circumferential end of the bias magnetic field generating portion 31, if it is positioned near the circumferential end (outer than the magnetic flux density detecting portions 32 at both ends), it can be formed at the circumferential end. You can get the same effect as

Comparative example 2.
As Comparative Example 2, an example in which the projecting portion is provided at the installation portion of the magnetic flux density detection portion, that is, at the root side of the magnetic flux density detection portion is shown. FIG. 6 is for explaining the configuration of the rotation angle detection device according to Comparative Example 2, and is an enlarged schematic diagram corresponding to FIG. is. 7 shows the ratio of the secondary harmonic component to the signal components of the three magnetic flux density detectors in each of the rotation angle detectors of Comparative Examples 1 and 2, using the signal of the central magnetic flux density detector as a reference. It is a comparative bar graph. Among the members of Comparative Example 2, the members having different structures to be compared with those of Example 1 are denoted by "R" at the end of the reference numerals.

In the rotation angle detection device according to Comparative Example 2, as shown in FIG. As shown in FIG. 7, in the case of Comparative Example 2 in which the protruding portion 31pR is installed at the position of the magnetic flux density detecting portion 32, the provision of the protruding portion 31pR causes the Hs/S ratio of the signals A and C to The difference value increases by 0.6%, and the imbalance of the output signal of each magnetic flux density detector 32 increases.

As described above, in order to reduce the imbalance of the output signal of the magnetic flux density detection section 32, it is necessary to arrange the projecting portion 31p at least outside the magnetic flux density detection section 32 in the circumferential direction Dc. By setting the arrangement position and the amount of protrusion Hp in this way, even if the bias magnetic field generating section 31 is made smaller in the circumferential direction, the magnetic flux density distribution becomes uniform over a wide range in the circumferential direction. output signal imbalance is reduced, and deterioration of angle detection accuracy can be suppressed.

Therefore, for example, the configuration disclosed in JP-A-2020-176853, in which the magnetic flux density generating portion is arranged in a range of less than half a cycle with respect to the uneven portion to reduce the size, has a particularly remarkable effect. It is possible to demonstrate

In the first embodiment, the portion where the protruding portion 31p is formed is thicker than the radial thickness at the position where the magnetic flux density detecting portion 32 of the bias magnetic field generating portion 31 is arranged. In the configuration in which the thickness at or near the ends in the circumferential direction is increased, in addition to the effect obtained by approaching the center X2, the amplitude of the output waveform of the magnetic flux density detection units 32 located at both ends in the circumferential direction Dc is increased, and the resistance is increased. It also has the effect of improving noise resistance.

Second modification.
In the above example, the stator is composed of the bias magnetic field generating section and the magnetic flux density detecting section. In the second modified example, an example in which a magnetic body is provided on the radially outer (back side) portion of the bias magnetic field generating portion will be described. FIG. 8 is for explaining the configuration of the rotation angle detection device according to the second modification, and is an enlarged schematic diagram corresponding to FIG. It is a diagram.

In the rotation angle detection device 1 according to the second modification, as shown in FIG. 8, a magnetic body 33 is provided so as to surround the radially outer side of the bias magnetic field generating portion 31 from one end side to the other end side in the circumferential direction. As a result, a magnetic path is formed through which the magnetic flux generated by the bias magnetic field generating section 31 passes, and the amplitude of the output waveform obtained by the magnetic flux density detecting section 32 increases, thereby improving noise resistance.

The bias magnetic field generator 31 may use a plastic magnet obtained by injection-molding magnetic particles together with a thermoplastic resin. Thereby, the strength of the member can be ensured even in a thin shape. In addition, it is possible to easily form the bias magnetic field generating section 31 having a relatively complicated surface shape provided with unevenness on the surface, and the bias magnetic field generating section 31 used in the rotation angle detecting device 1 of the present application is constructed. It can be suitably used as a material.

In the rotation angle detection device 1 disclosed in Embodiment 1 and subsequent embodiments, the angle calculation unit 5 includes, for example, hardware 500 including a processor 501 and a storage device 502 as shown in FIG. can be written as The storage device 502 includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory (not shown). Also, an auxiliary storage device such as a hard disk may be provided instead of the flash memory. Processor 501 executes a program input from storage device 502 . In this case, the program is input from the auxiliary storage device to the processor 501 via the volatile storage device. Further, the processor 501 may output data such as calculation results to the volatile storage device of the storage device 502, or may store the data in an auxiliary storage device via the volatile storage device.

Embodiment 2.
In Embodiment 1, an example is shown in which a protruding portion protruding from other portions is provided at the circumferential end portion of the bias magnetic field generating portion, but the present invention is not limited to this. In the second embodiment, an example will be described in which the protruding portion is formed by making the facing surface have a larger curvature than the arc whose radius is the distance from the center. FIG. 10 is for explaining the configuration of the rotation angle detection device according to the second embodiment. 3B is an enlarged schematic diagram corresponding to FIG. 3A used in FIG. It should be noted that in the second embodiment and subsequent embodiments, the description will focus on the differences from the first embodiment and related aspects, and the description of the same portions will be omitted as appropriate. In addition, FIGS. 1, 2, 4, etc. used in Embodiment 1 are used.

In the rotation angle detection device 1 according to the second embodiment, as shown in FIG. 10, the surface (back surface 31fo) of the bias magnetic field generating unit 31 opposite to the surface 31fc facing the rotor 2 is cross-sectionally perpendicular to the rotation axis. The shape is a segment of a circular arc, ie, a cylindrical surface, each with a different curvature. Then, by making the curvature of the facing surface 31fc larger than that of a circle whose radius is the distance from the center X2, the protruding portion 31p that protrudes from the facing surface 32fc of the magnetic flux density detecting portion 32 at both ends in the circumferential direction Dc is formed. .

As a result, a portion (protruding portion 31p) closer to the center X2 than the facing surface 32fc is provided at the end in the circumferential direction. A reduction effect can be obtained. Moreover, since the projecting portion 31p is formed by increasing the curvature of the facing surface 31fc, there is no need to provide a local projecting structure in the bias magnetic field generating portion 31, thereby improving productivity and member strength.

Furthermore, by making the curvature of the back surface 31fo smaller than the curvature of the opposing surface 31fc, it is possible to form a structure in which the radial thickness increases from the center toward the ends in the circumferential direction Dc. Therefore, it is possible to increase the amplitude of the output waveform of the magnetic flux density detectors 32 located at both ends in the circumferential direction Dc, and to improve the noise resistance.

Embodiment 3.
In Embodiments 1 and 2 above, an example in which a total of two projecting portions are formed only at or near both ends in the circumferential direction has been described. In the third embodiment, an example in which protrusions are provided between both ends and each magnetic flux density detection unit will be described. FIGS. 11A and 11B show the vicinity of the portion where the rotor and the stator of the rotation angle detection device according to Embodiment 3 and its modification are opposed to FIG. 3A used for explanation of Embodiment 1, respectively. It is a corresponding enlarged schematic diagram. Further, FIG. 12 is a diagram showing the second order for the signal components of the three magnetic flux density detection units in each of the rotation angle detection devices of Example 2 and Comparative Example 1 for explaining the effect of the rotation angle detection device according to Embodiment 3. 4 is a bar graph comparing the ratio of harmonic components with the signal from the center magnetic flux density detection unit as a reference.

In the rotation angle detection device 1 according to the third embodiment, as shown in FIG. 11A, the surface 31fc of the bias magnetic field generation unit 31 facing the rotor 2 has a concave portion where the magnetic flux density detection unit 32 is arranged. As shown, unevenness was formed along the circumferential direction Dc. A portion of the bias magnetic field generating portion 31 where the magnetic flux density detecting portion 32 is arranged becomes a concave portion, and a section therebetween and convex portions at both ends become a projecting portion 31p.

Even when the projecting portions 31p are formed also in the portion between the magnetic flux density detecting portions 32, as in the first embodiment, the projecting portions 31p are provided at both ends in the circumferential direction Dc. The effect of reducing the imbalance of the output signal of the magnetic flux density detector 32 can be obtained. Moreover, since the protruding portion 31p is formed between the adjacent bias magnetic field generating portions 31, the amplitude of the output waveform of each magnetic flux density detecting portion 32 increases, thereby improving the noise resistance. In addition, since the protruding portion 31p is located in the vicinity of all the magnetic flux density detection portions 32 in the circumferential direction Dc (a portion closer than the adjacent magnetic flux density detection portions), the magnetic flux density distribution around each magnetic flux density detection portion 32 is the same. become. As a result, the imbalance between the output signals of the magnetic flux density detectors 32 is further reduced, and the angle detection accuracy can be improved.

As for the effect, Example 2 (FIG. 11A) in which a projecting portion 31p is also provided between the adjacent magnetic flux density detecting portions 32 and Comparative Example 1 in which the bias magnetic field generating portion used in the explanation of FIG. The result of comparing the characteristics will be described with reference to FIG. 12 . As shown in FIG. 12, secondary harmonic components (differences from signal B) are generated in signals A and C regardless of the presence or absence of protrusion 31p. The difference is 1.6%, which is 0.3% lower than 1.9% in Example 1, and the difference value is reduced by 16% compared to Comparative Example 1. That is, even if the projecting portion 31p is provided in the adjacent portion, the presence of the projecting portion 31p at or near the circumferential end of the bias magnetic field generating portion 31 may cause the output signal of each magnetic flux density detecting portion 32 to become inconsistent. Equilibrium is reduced.

Modification.
In FIG. 12, the effect of the rotation angle detection device 1 of the second embodiment in which rectangular irregularities are formed along the circumferential direction on the surface of the bias magnetic field generating section facing the rotor has been described. In this modified example, as shown in FIG. 11B, curved unevenness is formed on the facing surface 31fc along the circumferential direction Dc. Even in this case, similarly to the rectangular unevenness described in FIG. 11A, the effect of reducing the imbalance of the output signal of each magnetic flux density detection unit 32 and the imbalance of the output signal of each magnetic flux density detection unit 32 are further reduced. It is possible to obtain the effect of improving the angle detection accuracy.

Embodiment 4.
In each of the above-described embodiments, examples have been described in which, in the bias magnetic field generating portion, the thickness in the radial direction of the portion where the projecting portion is formed increases in accordance with the projecting portion. In the fourth embodiment and the following embodiments, an example in which a recessed portion is provided on the rear surface side so as to compensate for the thickness change due to the protrusion on the opposing surface side will be described. FIG. 13 is for explaining the configuration of the rotation angle detection device according to the fourth embodiment. 3B is an enlarged schematic diagram corresponding to FIG. 3A used in FIG.

In the rotation angle detection device 1 according to the fourth embodiment, as shown in FIG. 13, the magnetic flux density detection section 32 is arranged on the back surface 31fo of the bias magnetic field generation section 31 corresponding to the formation of the projecting section 31p on the facing surface 31fc. A recessed portion 31d is formed which is closer to the center X2 than the portion where the recessed portion is formed. The recessed portion 31d has a depth equivalent to the protrusion Hp of the projecting portion 31p on the facing surface 31fc so as to compensate for the increase in volume (thickness) of the bias magnetic field generating portion 31 due to the provision of the projecting portion 31p. This should be set. For example, the thickness in the radial direction of the bias magnetic field generating portion 31 may be the same or the same in the region in which the projecting portion 31p and the recessed portion 31d are provided and in other regions.

Since the rotation angle detection device 1 according to the fourth embodiment has the projecting portion 31p at the circumferential end of the bias magnetic field generating portion 31, as in the first embodiment, the output signals of the magnetic flux density detecting portions 32 are unbalanced. can be obtained. Further, by providing the recessed portion 31d having a recessed amount corresponding to the amount of protrusion of the projecting portion 31p on the back surface 31fo side, the volume of the bias magnetic field generating portion 31 is not increased, and resources can be used more effectively.

Embodiment 5.
In the above-described Embodiment 4, an example in which recessed portions are formed on the back surface corresponding to the arrangement of the projecting portions illustrated in Embodiment 1 has been described, but the present invention is not limited to this. In the fifth embodiment, an example will be described in which recessed portions are formed corresponding to the protruding portions arranged between the adjacent magnetic flux density detecting portions as exemplified in the third embodiment.

FIGS. 14A and 14B show the vicinity of the portion where the rotor and the stator of the rotation angle detection device according to the fifth embodiment and its modification are opposed to each other, which is shown in FIG. 3A used for explaining the first embodiment. It is a corresponding enlarged schematic diagram. 15 is an enlarged view corresponding to FIG. 3A used for explaining the first embodiment, in the vicinity of a portion where the rotor and the stator of the rotation angle detection device according to the second modification of the fifth embodiment face each other. It is a schematic diagram.

In the rotation angle detection device 1 according to the fifth embodiment, as shown in FIG. 14A, the surface 31fc facing the rotor 2 has adjacent magnetic fluxes in addition to both ends, as in FIG. 11A of the third embodiment. It is also arranged between the density detection units 32, and three or more projections 31p are formed. Further, recessed portions 31d are formed on the rear surface 31fo so as to correspond to the three or more projecting portions 31p and to be closer to the center X2 than the portion where the magnetic flux density detecting portion 32 is arranged.

The recessed portions 31d corresponding to the three or more projecting portions 31p are also formed in such a manner as to compensate for the increase in volume (thickness) of the bias magnetic field generating portion 31 due to the provision of the projecting portions 31p. It is preferable to set the depth to the same extent as the amount of protrusion Hp.

Since the rotation angle detection device according to the fifth embodiment has the projecting portion 31p at or near the circumferential end of the bias magnetic field generating portion 31, as in the first embodiment, the output of each magnetic flux density detecting portion 32 is This has the effect of reducing signal imbalance. Furthermore, since the protruding portions 31p are also provided between the adjacent magnetic flux density detection portions 32, the amplitude of the output waveform of each magnetic flux density detection portion 32 is increased and the noise resistance is improved as in the third embodiment. effect is obtained. Since the depressed portion 31d is provided so as to compensate for the increase in thickness due to the projecting portion 31p, the same effect as in the third embodiment can be obtained without increasing the volume of the bias magnetic field generating portion 31, as in the fourth embodiment. can get.

Modification.
In FIG. 14A, corresponding to the third embodiment (FIG. 11A), the formation of recessed portions corresponding to rectangular protrusions formed along the circumferential direction has been described. In this modification, as shown in FIG. 14B, corresponding to the modification of the third embodiment (FIG. 11B), recessed portions corresponding to protruding portions 31p formed in a curved shape along the circumferential direction Dc 31d was formed. Even in this case, the effect of reducing the imbalance of the output signal of each magnetic flux density detection unit 32, the effect of further reducing the imbalance of the output signal of each magnetic flux density detection unit 32, the effect of improving the angle detection accuracy, and the effect of generating a bias magnetic field These effects can be obtained without increasing the volume of the portion 31 .

Second modification.
In the second modification, the magnetic body described in the second modification of the first embodiment is arranged in the bias magnetic field generating portion having recesses corresponding to the projections curved along the circumferential direction. An example will be described. In the second modification of the fifth embodiment, as shown in FIG. 15, the magnetic field is circumferentially extended toward the back surface 31fo of the bias magnetic field generating unit 31 in accordance with the back surface 31fo that is curved by the recessed portion 31d. A body 33 has been placed.

As a result, a magnetic path is formed through which the magnetic flux generated by the bias magnetic field generating section 31 passes, and the amplitude of the output waveform obtained by the magnetic flux density detecting section 32 increases, thereby improving the noise resistance. When forming the bias magnetic field generating portion 31 having a curved shape with a constant thickness, the bias magnetic field generating portion 31 is formed using a bendable magnet sheet, and the curve of the inner peripheral surface 33fi of the preformed magnetic body 33 is formed. The bias magnetic field generating section 31 may be deformed and attached so as to match.

Furthermore, while this application describes various exemplary embodiments and examples, various features, aspects, and functions described in one or more of the embodiments may lie in particular embodiments. The embodiments can be applied singly or in various combinations. Therefore, numerous variations not illustrated are envisioned within the scope of the technology disclosed herein. For example, modification, addition or omission of at least one component, extraction of at least one component, and combination with components of other embodiments shall be included.

As described above, according to the rotation angle detection device 1 of the present application, the rotation angle detecting device 1 has the concave and convex portion 21 of the magnetic material in which the diameter of the outer peripheral surface 2fo periodically changes, and is rotatably supported around the rotating shaft 22. A bias magnetic field generating section 31 that faces the child 2 and a part of the outer peripheral surface 2fo of the rotor 2 in the circumferential direction Dc with a gap therebetween and generates a magnetic field between itself and the concave-convex portion 21, and a bias magnetic field generating section. A stator 3 having a plurality of magnetic flux density detection units 32 arranged along the circumferential direction Dc on the surface 31fc of the rotor 31 facing the rotor 2 and detecting the generated magnetic field, and in the circumferential direction Dc of the facing surface 31fc In the portion outside the portion where the plurality of magnetic flux density detection units 32 are arranged, out of the plurality of magnetic flux density detection units 32, the portion where the magnetic flux density detection unit 32 located at the end in the circumferential direction Dc is arranged Also, a protruding portion 31p protruding in the radial direction so as to approach (the center X2 of) the rotating shaft 22 is formed. As a result, by reducing the disturbance of the magnetic flux density vector at the ends in the circumferential direction, the imbalance in the magnetic flux density detection values of the magnetic flux density detection units 32 is reduced, and a compact and accurate rotation angle detection device 1 can be obtained. can be done.

At this time, if the projecting portion 31p is formed closer to (the center X2 of) the rotating shaft 22 than (the facing surface 32fc of) the magnetic flux density detecting portion 32 located at the end, the magnetic flux density detecting portion 32 The circumferential component (disturbance component) of the magnetic flux density is reduced, and the radial component (signal component) of the magnetic flux density is increased. As a result, since the second harmonic component Hs with respect to the signal component S becomes smaller, the angle error can be further reduced. Furthermore, since the signal component S itself also increases, the noise resistance is further improved.

Further, if the portion of the bias magnetic field generating portion 31 where the projecting portion 31p is formed is configured to be thicker in the radial direction than the other portions, in addition to the effect obtained by approaching the center X2, It is possible to increase the amplitude of the output waveform of the magnetic flux density detectors 32 located at both ends in the circumferential direction Dc, and to improve the noise resistance.

Alternatively, the magnetic flux density detection unit 32 positioned at the end is located at the same position in the circumferential direction Dc as the portion of the rear surface 31fo in the radial direction of the bias magnetic field generation unit 31 where the projecting portion 31p is formed on the opposing surface 31fc. If the recessed portion 31d is formed so as to be recessed closer to the rotating shaft 22 than the portion at the same position in the circumferential direction Dc as the arranged portion, an increase in the volume of the bias magnetic field generating portion 31 can be suppressed. , resources can be used effectively.

In addition, since the cross-sectional shape of the facing surface 31fc perpendicular to the rotating shaft 22 is an arc with a larger curvature than a circle whose radius is the distance from the rotating shaft 22 (center X2), the projecting portion 31p can be easily formed. can.

Moreover, if the protruding portion 31p is also formed in an intermediate portion between the magnetic flux density detecting portions 32 adjacent to each other in the circumferential direction Dc among the plurality of magnetic flux density detecting portions 32, each magnetic flux density detecting portion 32 increases the amplitude of the output waveform, improving noise immunity.

If the stator 3 extends in the circumferential direction Dc and has a magnetic body 33 arranged radially outwardly of the bias magnetic field generating section 31, the magnetic flux generated from the bias magnetic field generating section 31 passes through. A path is formed, and the amplitude of the output waveform obtained by the magnetic flux density detection unit 32 increases, thereby improving noise resistance.

Three magnetic flux density detectors 32 are arranged along the circumferential direction Dc as a plurality of magnetic flux density detectors 32. The signals from each of the three magnetic flux density detectors 32 are two-phase-converted, and the rotor 2 is detected by an arctangent function. Robustness against third-order harmonic components can be provided by providing the angle calculator 5 for calculating the rotation angle θ.

In the case where three magnetic flux density detection units 32 are provided, the effects described above can be obtained. The number of density detection units 32 may be further increased. If at least three or more magnetic flux density detection units 32 are provided, it is possible to provide robustness to specific high frequency components. Further, if a plurality of magnetic flux density detection units 32 are provided, the basic effect of the rotation angle detection device 1 disclosed in the present application, which is to reduce the unbalance of the output signals of each magnetic flux density detection unit 32, can be obtained in common. can be done.

1: Rotation angle detector 2: Rotor 21: Concavo-convex portion 22: Rotating shaft 2fo: Peripheral surface 3: Stator 31: Bias magnetic field generator 31d: Depression 31fc: Opposite surface 31fo : back surface 31p: protrusion 32: magnetic flux density detector 32fc: facing surface 33: magnetic material 33fi: inner peripheral surface 5: angle calculator Dc: circumferential direction Hp: amount of protrusion X2: center , θ: rotation angle.

The rotation angle detection device disclosed in the present application includes a rotor having irregularities made of a magnetic material in which the diameter of the outer peripheral surface periodically and smoothly changes, and which is rotatably supported around a rotation shaft; and the rotor. a bias magnetic field generating portion that faces a part of the outer peripheral surface of the in the circumferential direction with a space therebetween and generates a magnetic field between itself and the uneven portion; and a surface of the bias magnetic field generating portion that faces the rotor. a stator having a plurality of magnetic flux density detection units arranged along the circumferential direction and detecting the generated magnetic field, wherein the plurality of magnetic flux density detection units are arranged in the circumferential direction of the facing surface Out of the plurality of magnetic flux density detection units, the outer portion protrudes in the radial direction so as to be closer to the rotating shaft than the portion where the magnetic flux density detection unit positioned at the end in the circumferential direction is arranged. characterized in that a projecting portion is formed to

Claims (8)

A rotor having irregularities made of a magnetic material whose diameter on the outer peripheral surface changes periodically, and is rotatably supported around a rotation axis; a bias magnetic field generating portion facing the uneven portion with a space therebetween and generating a magnetic field between the concave and convex portion; A stator having a plurality of magnetic flux density detection units that detect a magnetic field generated by
A magnetic flux density detector positioned at an end portion in the circumferential direction among the plurality of magnetic flux density detectors is provided in a portion of the facing surface outside the portion where the plurality of magnetic flux density detectors are arranged in the circumferential direction. A rotation angle detection device, wherein a protruding portion protruding in a radial direction is formed so as to be closer to the rotating shaft than a portion where the portion is arranged. 2. The rotation angle detection device according to claim 1, wherein the protruding portion is formed closer to the rotating shaft than the magnetic flux density detection portion positioned at the end portion. 3. The rotation angle detection device according to claim 1, wherein the portion of the bias magnetic field generating portion where the projecting portion is formed is thicker in the radial direction than other portions. A magnetic flux density detection unit located at the end is arranged in a portion of the rear surface of the bias magnetic field generation unit in the radial direction, which is at the same position in the circumferential direction as the portion of the facing surface where the protrusion is formed. 3. The rotation angle detection device according to claim 1, further comprising a recessed portion that is recessed so as to be closer to the rotating shaft than the portion located at the same position in the circumferential direction. 4. A cross-sectional shape of the opposing surface perpendicular to the rotation axis is an arc having a larger curvature than a circle whose radius is the distance from the rotation axis. The rotation angle detection device according to . 6. The protruding portion is also formed in an intermediate portion between the magnetic flux density detecting portions adjacent in the circumferential direction among the plurality of magnetic flux density detecting portions. The rotation angle detection device according to . 7. The stator according to any one of claims 1 to 6, wherein the stator extends along the circumferential direction and has a magnetic body arranged outside the bias magnetic field generating portion in the radial direction. Rotation angle detector. Three magnetic flux density detection units are arranged along the circumferential direction as the plurality of magnetic flux density detection units,
8. The apparatus according to any one of claims 1 to 7, further comprising an angle calculation section that performs two-phase conversion on the signals from each of the three magnetic flux density detection sections and calculates the rotation angle of the rotor using an arctangent function. 4. A rotation angle detection device according to claim 1.

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