JP2008292466A - Angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angle detector increasing the detection accuracy and reducing manufacturing cost. <P>SOLUTION: The angle detector comprises: a rotating member 2 having N pole areas 5 and S pole areas 6 disposed alternately around the center of rotation; a magnetic field detecting section 3 having a sheet-like magnetic plate 8 and a pair of detection elements 9 for detecting the magnitude of a field component in a direction perpendicular to the magnetic plate 8; and a processing section 4 for calculating a rotational angle of a rotating member 2 according to the detection information of the magnetic field detecting section 3. The magnetic field detecting section 3 disposes the magnetic plate 8 so that the plate 8 is perpendicular to the first direction Z at which the maximum magnetic field is obtained around the rotating member 2 to detect the magnitudes of magnetic field components in both the first direction Z and the second direction X along the boundary of the N pole region 5 and the S pole region 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention includes a rotating member in which an N-pole region having an N polarity and an S-pole region having an S polarity are alternately arranged around a rotation center, and a pair of detection elements that detect a magnetic field generated around the rotating member. The present invention relates to an angle detection apparatus provided with a magnetic field detection unit having a calculation unit that calculates a rotation angle of the rotation member based on detection information of the magnetic field detection unit.

The angle detection device as described above is used, for example, as a steering angle sensor for an automobile or a shift position sensor for a transmission.
In such an angle detection device, the magnetic field detection unit detects the magnitude of the magnetic field component in two directions with respect to the magnetic field generated around the rotating member. The two directions are the radial direction of the rotating member and the arrangement direction of the N-pole region and the S-pole region orthogonal thereto. The computing means obtains the rotation angle of the rotating member from the ratio of the magnitudes of the two-direction magnetic field components detected by the magnetic field detector. (For example, refer to Patent Document 1).

The magnetic field detector is, for example, a Hall IC as shown in FIG.
The magnetic field detection unit 3 includes a magnetic plate 8 and a pair of detection elements 9 that detect a magnetic field generated around the rotating member. The magnetic plate 8 is formed in a disc shape. A pair of detection elements (Hall elements) 9 are arranged immediately below the end of the magnetic plate 8. The pair of detection elements 9 is provided in two sets, one set 9a, 9b arranged along the X direction and one set 9c, 9d arranged along the Y direction.

  In the conventional angle detection device, for example, as shown in FIG. 15, the rotary member 2 fitted on the rotary shaft 1 faces the N pole region 5 and the S pole region 6 outward in the radial direction. It is arranged. The magnetic field detection unit 3 is disposed on the substrate 7 on the radially outer side of the rotating member 2 that faces the N-pole region 5 and the S-pole region 6. The magnetic field detector 3 is arranged so as to face the magnetic plate 8 in parallel with the radial direction of the rotating member 2, and the radial direction of the rotating member 2 and the arrangement direction of the N-pole region 5 and the S-pole region 6. The magnitude of the magnetic field component in two directions is detected.

The detection principle of the magnetic field detection unit 3 will be described with reference to FIGS. FIG. 3A and FIG. 3B are cross-sectional views in the direction of the direction of X in FIG. 2 and show the state of magnetic flux.
In this example, the radial direction of the rotating member 2 is the Y direction, the arrangement direction of the N pole region 5 and the S pole region 6 is the X direction, and the direction perpendicular to both is the Z direction.

As shown in FIG. 3B, when an external magnetic field is applied in the Y direction, a magnetic flux is bent by the magnetic plate 8, and the pair of detection elements 9c and 9d arranged along the Y direction includes a magnetic plate. A magnetic field component in the Z direction perpendicular to 8 is generated. At this time, the magnitude of the magnetic field component in the Z direction is proportional to the magnitude of the external magnetic field, and the direction of the generated magnetic field component is opposite in the detection element 9c and the detection element 9d. Therefore, a magnetic field component proportional to the magnitude of the external magnetic field in the Y direction can be detected by calculating the difference between the output voltages of the pair of detection elements 9c and 9d.
On the other hand, when an external magnetic field is applied in the X direction, a magnetic field component in the Z direction perpendicular to the magnetic plate 8 is generated in the same manner as when an external magnetic field is applied in the Y direction. Therefore, the magnetic field detection unit 3 can detect the magnitude of the magnetic field component in the X direction by calculating the difference between the output voltages of the pair of detection elements 9a and 9b arranged along the X direction.

  When a disturbance magnetic field exists, the disturbance magnetic field can be removed as follows. As shown in FIG. 3A, when a disturbance magnetic field is applied in the Z direction, the pair of detection elements 9c and 9d arranged along the Y direction has a magnetic field component in the Z direction perpendicular to the magnetic plate 8. appear. At this time, the direction of the generated magnetic field component is the same in the detection element 9c and the detection element 9d. Therefore, the disturbance magnetic field applied in the Z direction can be set to 0 (zero) by calculating the difference between the output voltages of the pair of detection elements 9c and 9d.

JP 2007-40850 A

In the conventional angle detection device, as shown in FIG. 19, the distance R from the surface of the N pole region 5 and the S pole region 6 to the magnetic field detection unit 3 is long in the radial direction of the rotating member 2. Therefore, in order to set the magnetic field intensity applied to the magnetic field detector 3 to a desired magnetic field intensity, the N-pole region 5 and the S-pole region 6 must be formed of a rare earth magnet having a high magnetic force, resulting in an increase in cost. It was.
On the other hand, if the distance R from the surface of the N pole region 5 and the S pole region 6 to the magnetic field detection unit 3 is shortened, the magnetic field strength applied to the magnetic field detection unit may become too large. When the intensity of the magnetic field applied to the magnetic field detector becomes too large, the magnetic flux on the magnetic plate becomes too dense and a magnetic saturation state occurs. When the magnetic plate is magnetically saturated, a magnetic field having a strength proportional to the external magnetic field is not generated in the vertical direction of the magnetic plate. Therefore, if the distance R from the surface of the N pole region 5 and the S pole region 6 to the magnetic field detection unit 3 is shortened, the magnetic field detection unit may not be able to detect the magnitude of the magnetic field component in two directions.

In the conventional angle detection apparatus as shown in FIG. 19, the magnetic field strength applied to the magnetic field detection unit 3 is not constant and varies depending on the rotation angle of the rotating member 2 as shown in FIG. 20. FIG. 20 shows the magnetic field strength applied to the magnetic field detector 3 when the rotation angle of the rotating member 2 is changed. In the state shown in FIG. 19, the rotation angle of the rotating member 2 is set to 0 (zero) deg. Further, the strength of the magnetic field applied to the magnetic field detection unit also varies depending on variations in dimensions and characteristics of the magnetic field detection unit.
A desirable magnetic field intensity range (for example, 20 to 70 mT) for operating the magnetic field detector is defined. Since the upper limit magnetic field strength is defined, the operating magnetic field of the magnetic field detector cannot be made larger than the upper limit magnetic field strength. In addition, as described above, since the magnetic field strength applied to the magnetic field detection unit varies, the operating magnetic field of the magnetic field detection unit may become small. Therefore, it becomes easy to receive the influence of a disturbance magnetic field, and there exists a possibility that the detection accuracy of an angle detection apparatus may fall. Therefore, it is necessary to take measures such as providing a magnetic shield, which increases the cost of the angle detection device.

  The present invention has been made in view of the above problems, and an object thereof is to provide an angle detection device capable of improving detection accuracy and reducing costs.

  In order to achieve this object, the angle detection device according to the present invention includes a rotating member in which an N-pole region having an N polarity and an S-pole region having an S polarity are alternately arranged around a rotation center; A magnetic field detector having a plate-like magnetic plate and a pair of detection elements for detecting the magnitude of the magnetic field component in a direction perpendicular to the magnetic plate, and the rotation angle of the rotating member based on detection information of the magnetic field detector And the magnetic field detector is arranged so as to face the magnetic plate perpendicular to the first direction in which the maximum magnetic field is obtained for the magnetic field generated around the rotating member, and The configuration is such that the magnitude of the magnetic field component in two directions of the first direction and the second direction along the alignment direction of the N-pole region and the S-pole region is detected.

Since the magnetic plate is plate-shaped, the degree of magnetization varies depending on the direction in which the external magnetic field is applied. Usually, it is harder to magnetize when an external magnetic field is applied vertically than when an external magnetic field is applied in parallel. Therefore, when an external magnetic field is applied perpendicularly to the magnetic plate, the magnetic plate is less likely to be magnetically saturated than when an external magnetic field is applied parallel to the magnetic plate.
Therefore, in this configuration, the magnetic field detector is arranged so as to face the magnetic plate perpendicular to the first direction, and the magnetic field intensity until the magnetic plate is in a magnetic saturation state is increased. Therefore, the distance from the surface of the N-pole region and the S-pole region to the magnetic field detector can be shortened, and it is not necessary to form the N-pole region and the S-pole region with a high-magnetism rare earth magnet, etc. Miniaturization can be achieved. In addition, the magnetic field intensity until the magnetic plate is magnetically saturated can be increased, and the upper limit value of the magnetic field intensity desirable for operating the magnetic field detector can be set larger. Therefore, the operating magnetic field of the magnetic field detector can be increased in magnetic field strength, and detection accuracy can be improved and costs can be reduced.

  Another characteristic configuration of the angle detection device according to the present invention is that the N-pole region and the S-pole region are arranged so that the first direction and the second direction are orthogonal to each other.

  With this arrangement, it is easy to adjust the orientation and orientation of the magnetic field detection unit when arranging the magnetic field detection unit. Therefore, the magnetic field detector can be easily arranged.

  Another characteristic configuration of the angle detection device according to the present invention is that the pair of detection elements are arranged along the second direction.

  With this arrangement, the magnitude of the magnetic field component in the second direction can be directly detected by the pair of detection elements, and the magnitude of the magnetic field component in the second direction can be accurately detected.

  Another characteristic configuration of the angle detection device according to the present invention is that the pair of detection elements are orthogonal to the second direction and a set arranged along the second direction on a plane perpendicular to the first direction. There are two sets, one set arranged along the direction.

For example, a pair of detection elements that detect the magnitude of the magnetic field component in the second direction are assigned to a pair of detection elements arranged along the second direction, and the pair of detection elements that detect the magnitude of the magnetic field component in the first direction Can be assigned to a pair of detection elements arranged along a direction orthogonal to the second direction. Therefore, the magnitude of the magnetic field component in two directions can be detected simply by each of the assigned pair of detection elements detecting the magnitude of the magnetic field component, and the detection configuration can be simplified.
In addition, for example, the first value is obtained by obtaining an average value of the detection value in the pair of detection elements arranged along the second direction and the detection value in the pair of detection elements arranged along the direction orthogonal to the second direction. The magnitude of the magnetic field component in the direction or the second direction can also be detected. As described above, the magnitudes of the magnetic field components in the two directions can be accurately detected using two pairs of detection elements.

  Another characteristic configuration of the angle detection device according to the present invention is that the rotating member is disposed so that each of the N-pole region and the S-pole region faces radially outward, and the magnetic field detection is performed. The portion lies in that it is arranged radially outward of the rotating member that faces the N-pole region and the S-pole region, respectively.

  With such an arrangement, the magnetic field detector can be arranged so that the magnetic plate faces the rotation center of the rotating member in parallel. Therefore, the magnetic field detector can be thinned in the radial direction of the rotating member, and the radial size of the rotating member can be reduced. In addition, since the distance between the surface of the N-pole region and the S-pole region and the magnetic field detection unit can be reduced, the magnetic field detection unit can be disposed closer to the rotation member in the radial direction of the rotation member. It is possible to effectively reduce the direction.

  Another characteristic configuration of the angle detection device according to the present invention is that the N-pole region and the S-pole region are arranged so that the first direction is parallel to the rotation center, and the magnetic field detection unit includes: It exists in the point arrange | positioned in the direction parallel to the said rotation center with respect to each of the said N pole area | region and the said S pole area | region.

  With such an arrangement, the magnetic field detector can be arranged so that the magnetic plate faces in parallel with the radial direction of the rotating member. Therefore, the magnetic field detector can be made thin in the axial direction of the rotating member, and the rotating member can be downsized in the axial direction. In addition, since the distance between the surface of the N-pole region and the S-pole region and the magnetic field detector can be reduced, the magnetic field detector can be disposed closer to the rotating member in the axial direction of the rotating member. It is possible to effectively reduce the size in the axial direction.

  Another characteristic configuration of the angle detection device according to the present invention is that the N-pole region and the S-pole region are formed of an annular or circular polar anisotropic magnet.

  As shown in the simulation results to be described later, by using polar anisotropic magnets as the rotating member, fluctuations in the direction of the magnetic field that occurs when the radial distance between the rotating member and the magnetic field detector varies are reduced. can do. For this reason, by using a polar anisotropic magnet as the rotating member, it is possible to reduce fluctuations in the detection result due to the influence of the assembly error of the angle detection device. Further, even when the radial distance between the rotating member and the magnetic field detector varies due to the shake of the rotating shaft when the angle detector is used, fluctuations in the detection result can be reduced.

  Another characteristic configuration of the angle detection device according to the present invention is that the N-pole region and the S-pole region are magnetized so that the distribution of the magnetic field strength on the surface facing the magnetic field detection unit is a sine wave. It is in the point formed with the toric or circular isotropic magnet.

  Even when an isotropic magnet magnetized so that the magnetic field strength distribution on the surface facing the magnetic field detector is a sine wave is used as the rotating member, the same effect as in the case of the polar anisotropic magnet is obtained. be able to. Generally, an isotropic magnet has a lower manufacturing cost than a polar anisotropic magnet, and the manufacturing cost can be reduced by using an isotropic magnet as a rotating member.

  Another characteristic configuration of the angle detection device according to the present invention is such that the radial width of the magnet forming the N-pole region and the S-pole region is half the circumferential width of the N-pole region and the S-pole. The length is set to be larger than half the circumferential width of the polar region.

  When a polar anisotropic magnet or an isotropic magnet magnetized so that the magnetic flux density on the surface is distributed sinusoidally is used as the rotating member, the shape of the magnetic lines of force is the N pole region on the outer peripheral side surface of the rotating member. And a circular shape passing through the center of the N-pole region and the center of the S-pole region with the boundary between the S-pole region and the center. Therefore, the radial width of the magnet forming the N-pole region and the S-pole region is set to be larger than half the circumferential width of the N-pole region and half the circumferential width of the S-pole region. Thus, the distribution of magnetic flux density can be improved without interruption of the lines of magnetic force. As a result, the accuracy of the angle detection device can be increased.

  Another characteristic configuration of the angle detection device according to the present invention is that a groove extending in the circumferential direction is formed on the outer peripheral surface of the magnet forming the N-pole region and the S-pole region.

  As shown in the simulation results to be described later, the direction of the magnetic field generated when the relative position between the rotating member and the magnetic field detector changes by forming a groove on the outer peripheral surface of the magnet that forms the N-pole region and the S-pole region. Fluctuations can be reduced. For this reason, by forming a groove in the magnet, it is possible to reduce fluctuations in the detection result due to the influence of the assembly error of the angle detection device. Further, even when the relative position between the rotating member and the magnetic field detector varies due to the shake of the rotating shaft when the angle detector is used, fluctuations in the detection result can be reduced.

  Another characteristic configuration of the angle detection device according to the present invention is that the magnetic field detection unit and the magnet face each other in the groove forming region in the rotation axis direction of the rotation member.

  The effect of reducing fluctuations in the direction of the magnetic field that occurs when the relative position between the rotating member and the magnetic field detector changes is particularly noticeable in the region where the groove is formed. Therefore, the fluctuation of the detection result can be further reduced by making the magnetic field detection unit and the magnet face each other in the formation region.

An embodiment of an angle detection device according to the present invention will be described with reference to the drawings.
[First Embodiment]
As shown in FIG. 1, the angle detection device includes a rotation member 2 fitted around the rotation shaft 1, a magnetic field detection unit 3 that detects a magnetic field generated around the rotation member 2, and detection information of the magnetic field detection unit 3. And a calculation unit 4 as calculation means for obtaining the rotation angle of the rotary member 2 with respect to the magnetic field detection unit 3. Fig.1 (a) is a perspective view, FIG.1 (b) is sectional drawing in the direction view along the Y direction of Fig.1 (a).

  The rotating member 2 is provided so as to rotate integrally with the rotating shaft 1. The rotating member 2 is configured by a ring-shaped magnet in which N-pole regions 5 having N polarity and S-pole regions 6 having S polarity are alternately arranged around the rotation center. The rotating member 2 is provided with four each of the N-pole region 5 and the S-pole region 6 by setting the interval between the N-pole and the S-pole to 45 degrees. As the rotating member 2, a polar anisotropic magnet or a radial anisotropic magnet may be used. Alternatively, an isotropic magnet magnetized so that the surface magnetic flux density is distributed approximately sinusoidally may be used. However, as will be described later, it is preferable to use a polar anisotropic magnet or an isotropic magnet magnetized so that the magnetic flux density on the surface is distributed approximately sinusoidally.

  When the rotating member 2 is a polar anisotropic magnet or an isotropic magnet magnetized so that the magnetic flux density of the surface is distributed approximately sinusoidally, a plurality of conducting wires are provided in the circumferential direction of the magnet, and the conducting wire Magnetization is performed by energizing the current. Therefore, as shown in FIG. 8, the shape of the lines of magnetic force is such that the center of the N-pole region 5 and the S-pole region 6 center on the boundary between the N-pole region 5 and the S-pole region 6 on the outer peripheral side surface of the rotating member 2. A circular shape passing through the center. Therefore, the radial width of the magnets forming the N-pole region 5 and the S-pole region 6 is longer than half the circumferential width of the N-pole region 5 and half the circumferential width of the S-pole region 6. A large setting is preferable. With this setting, the lines of magnetic force are not interrupted, and the distribution of magnetic flux density can be improved.

The rotating member 2 is arranged so that each of the N-pole region 5 and the S-pole region 6 faces radially outward. The first direction in which the maximum magnetic field is obtained for the magnetic field generated around the rotating member 2 is the radial direction (Z direction) of the rotating member 2. A second direction orthogonal to the Z direction and along the alignment direction of the N-pole region 5 and the S-pole region 6 is the rotational direction (X direction) of the rotating member 2. In this way, the N-pole region 5 and the S-pole region 6 are arranged so that the first direction (Z direction) and the second direction (X direction) are orthogonal to each other.
A direction perpendicular to the second direction on the plane perpendicular to the first direction (Z direction) is defined as a third direction (Y direction). Therefore, the first direction (Z direction), the second direction (X direction), and the third direction (Y direction) are three directions orthogonal to each other. Hereinafter, the first direction is referred to as the Z direction, the second direction is referred to as the X direction, and the third direction is referred to as the Y direction.

The magnetic field detection unit 3 is, for example, a Hall IC, specifically, an MLX90316 manufactured by Melexis and provided on the substrate 7. However, in the commercially available standard MLX90316, the magnitude of the magnetic field component in the X direction and the Y direction is detected by calculating the difference between the output voltages of the pair of detection elements (9a, 9b and 9c, 9d). Thus, the internal circuit is fixed so that the direction of the magnetic field in the XY plane is calculated and a signal corresponding to the magnetic field angle is output. Therefore, in the present embodiment, for example, a Hall IC in which the internal circuit of the MLX90316 is changed so that predetermined signal processing can be performed is used. Here, in the present embodiment, the magnetic field detector 3 is arranged on the outer side in the radial direction of the rotating member 2 facing the N-pole region 5 and the S-pole region 6.
As shown in FIG. 2, the magnetic field detection unit 3 includes a disk-shaped magnetic plate 8 and a pair of detection elements 9 that detect the magnitude of a magnetic field component in a direction perpendicular to the magnetic plate 8. The detection element 9 is a Hall element, for example, and is provided immediately below the end of the magnetic plate 8. The pair of detection elements 9 is provided in two planes, one set 9a and 9b arranged along the X direction and one set 9c and 9d arranged along the Y direction on a plane perpendicular to the Z direction.

The magnetic field detector 3 is arranged so as to face the magnetic plate 8 perpendicularly to the Z direction, and is configured to detect the magnitude of the magnetic field component in the two directions of the Z direction and the X direction.
The principle of detecting the magnitude of the magnetic field component in the Z direction by the magnetic field detector 3 will be described.
As shown in FIG. 3A, when an external magnetic field is applied in the Z direction, a magnetic field component along the Z direction is generated in a pair of detection elements 9c and 9d arranged along the Y direction. At this time, the direction of the generated magnetic field component is the same in the detection element 9c and the detection element 9d. Therefore, a magnetic field component proportional to the magnitude of the external magnetic field can be detected by adding the output voltages of the pair of detection elements 9c and 9d.

  When a disturbance magnetic field exists, the disturbance magnetic field can be removed as follows. As shown in FIG. 3B, when a disturbance magnetic field is applied in the Y direction, the magnetic flux is bent by the magnetic plate 8, and a magnetic field component along the Z direction is generated in the pair of detection elements 9c and 9d. At this time, in the detection element 9c and the detection element 9d, the direction of the generated magnetic field component is opposite. Therefore, the disturbance magnetic field applied in the Y direction can be set to 0 (zero) by adding the output voltages of the pair of detection elements 9c and 9d.

  The principle of detection of the magnitude of the magnetic field component in the X direction by the magnetic field detector 3 is the same as the principle of detection of the magnitude of the magnetic field component in the X direction in the conventional angle detection device described with reference to FIG. Therefore, the magnetic field detector 3 detects the magnitude of the magnetic field component in the X direction by calculating the difference between the output voltages of the pair of detection elements 9a and 9b arranged along the X direction.

The calculation unit 4 obtains the rotation angle θ of the rotating member 2 based on the ratio between the magnitude Vz of the magnetic field component in the Z direction and the magnitude Vx of the magnetic field component in the X direction using the following [Equation 1].
[Formula 1]
θ = Arctan (Vz / Vx)

Hereinafter, effects of the angle detection device according to the present invention will be described.
Since the magnetic plate 8 has a disk shape, the degree of magnetization varies depending on the direction in which the external magnetic field is applied. FIG. 4 shows the result of analyzing the relationship between the external magnetic field and the maximum magnetization of the magnetic plate 8 by simulation. In the figure, ◇ indicates a case where an external magnetic field is applied in parallel to the magnetic plate 8. In the figure, □ indicates a case where an external magnetic field is applied perpendicularly to the magnetic plate 8.
4 that the magnetic plate 8 is harder to magnetize when an external magnetic field is applied vertically than when an external magnetic field is applied in parallel. As a result of the simulation, the magnetic field strength when the magnetic plate 8 is in a magnetic saturation state is approximately 6 times larger when the external magnetic field is applied vertically than when the external magnetic field is applied in parallel.

  If the magnetic field strength applied to the magnetic field detection unit 3 becomes excessive, the magnetic plate 8 is in a magnetic saturation state, and a magnetic field having a strength proportional to the external magnetic field cannot be generated in the vertical direction of the magnetic plate 8. As estimated from the results of FIG. 4 and the like, when the magnetic field detector 3 is arranged so that the magnetic plate 8 faces perpendicularly to the Z direction (see FIG. 1), the maximum allowable magnetic field of the magnetic field detector 3 is further increased. It is considered that a large magnetic field strength can be obtained.

  Therefore, when the magnetic field detector 3 is arranged so that the magnetic plate 8 faces perpendicularly to the Z direction, the result of calculating the maximum allowable magnetic field of the magnetic field detector 3 based on the result of FIG. Shown in 5 (b). FIG. 5B shows the maximum allowable magnetic field (Δ in the figure) of the magnetic field detector 3 when the angle α of the applied magnetic field applied to the magnetic field detector 3 is changed. The angle α of the applied magnetic field applied to the magnetic field detector 3 is shown in FIG. The maximum allowable magnetic field (Δ in the figure) when the angle α of the applied magnetic field is 0 deg is the upper limit (70 mT) of the magnetic field strength range desirable for operating the magnetic field detector 3. If the angle α of the applied magnetic field at this time is shown in FIG. 1, the magnetic field detector 3 is positioned so as to face the middle between the N-pole region 5 and the S-pole region 6 (the rotation angle of the rotating member 2). For example, ± 22.5 deg). This is the rotation angle at which the magnetic field strength is minimum as shown in FIG. In addition, the maximum allowable magnetic field (Δ in the figure) when the angle α of the applied magnetic field is −90 deg and 90 deg is set to 6 times (420 mT) the upper limit value of the magnetic field strength range desirable for operating the magnetic field detector 3. Can do. If the angle α of the applied magnetic field at this time is shown in FIG. 1, the magnetic field detector 3 is positioned so as to face the center of the N-pole region 5 or the S-pole region 6 (the rotation angle of the rotating member 2 is For example, 0 deg, ± 45 deg). This is the rotation angle at which the magnetic field strength is maximum as shown in FIG.

  In this way, when the magnetic field detector 3 is disposed so as to face the magnetic plate 8 perpendicularly to the Z direction, the angle of the applied magnetic field applied to the magnetic field detector 3 is other than 0 (zero) deg. In addition, the maximum allowable magnetic field of the magnetic field detector 3 can be set to a larger magnetic field strength.

Therefore, the operating magnetic field (A1 in the figure) of the magnetic field detecting unit can be set between the maximum allowable magnetic field (Δ in the figure) and the lower limit value (20 mT) of the desired magnetic field strength range for operating the magnetic field detecting part 3.
In the conventional angle detection device, the operating magnetic field (A2 in the figure) of the magnetic field detection unit is set between the magnetic field strength ranges (20 to 70 mT). The operating magnetic field (A1 in the figure) of the magnetic field detector 3 in the present invention can be about twice that of the conventional angle detector. Therefore, the operating magnetic field of the magnetic field detector 3 can be increased, and the detection accuracy can be improved and the cost can be reduced. In addition, the distance from the surface of the N pole region 5 and the S pole region 6 to the magnetic field detector 3 can be shortened, and it is not necessary to form the N pole region 5 and the S pole region 6 with a high-magnetism rare earth magnet or the like. It is possible to achieve reduction and downsizing.

As shown in FIG. 6, the magnitude of the magnetic field component applied to the magnetic field detection unit 3 by the magnetic field generated around the rotating member 2 differs between the Z direction (◇ in the figure) and the X direction (□ in the figure). ing. FIG. 6 shows a simulation calculation result for the rotating member 2 in which each of the N-pole region 5 and the S-pole region 6 is provided three by setting the interval between the N-pole and the S-pole to 60 degrees.
As a result of the simulation, the magnetic field strength ratio between the magnitude of the magnetic field component in the Z direction (◇ in the figure) and the magnitude of the magnetic field component in the X direction (□ in the figure) is 1.41 (= the magnetic field component in the Z direction). Magnitude / magnitude of the magnetic field component in the X direction).

  On the other hand, when an external magnetic field is applied in parallel to the magnetic plate 8, the magnetic collection effect of the magnetic plate 8 works strongly, and is about 1.8 times as large as the external magnetic field in the direction perpendicular to the magnetic plate 8 with respect to the detection element 9. The magnetic field is generated. On the other hand, when an external magnetic field is applied perpendicularly to the magnetic plate 8, the magnetic collection effect of the magnetic plate 8 is small and about 1.2 times as large as the external magnetic field in the direction perpendicular to the magnetic plate 8 relative to the detection element 9. A magnetic field is generated. Thus, the sensitivity of the magnetic field detection unit 3 varies depending on the direction in which the external magnetic field is applied. As a result of the simulation, the sensitivity ratio of the magnetic field detector 3 is calculated to be 1.48 (sensitivity in the direction parallel to the magnetic plate 8 / sensitivity in the direction perpendicular to the magnetic plate 8).

  Therefore, in the present invention, as shown in FIG. 1, the magnetic field detector 3 is disposed so that the magnetic plate 8 faces perpendicularly to the Z direction, and an external magnetic field is applied perpendicularly to the magnetic plate 8. . Therefore, the intensity ratio (1.41) of the magnetic field and the sensitivity ratio (1.48) of the magnetic field detection unit 3 can be canceled out, and the sensitivity as the angle detection device can be almost 1. As shown in FIG. 7, the angle detection apparatus according to the present invention can improve the linearity of the calculated value θ calculated by the calculation unit 4 with respect to the angle, and can improve the detection accuracy.

  Next, simulation results of the magnetic field strength (magnetic flux density) detected by the magnetic field detector 3 when a polar anisotropic magnet is used as the rotating member 2 and when a radial anisotropic magnet is used will be described. In the model used in the simulation, the rotating member is a ring-shaped magnet having an outer diameter of 21 mm (radius 10.5 mm), an inner diameter of 16.8 mm (radius 8.4 mm), and a thickness of 7 mm. It was assumed that four regions S were provided alternately at equal pitches.

FIG. 9A is a diagram illustrating a simulation result of a change in the magnetic field strength in the Z direction accompanying the rotation of the rotating member when a polar anisotropic magnet is used as the rotating member 2. Similarly, FIG. 9B is a diagram showing changes in the magnetic field strength in the X direction.
On the other hand, FIG. 10A is a diagram showing a simulation result of a change in magnetic field strength in the Z direction accompanying rotation of the rotating member when a radial anisotropic magnet is used as the rotating member 2. FIG. 10B is also a diagram showing changes in the magnetic field strength in the X direction. In each figure, the value in the figure indicates the distance (mm) between the center of the rotating member 2 and the magnetic field detector 3.

As can be seen from FIG. 9, when a polar anisotropic magnet is used as the rotating member 2, no matter what the distance from the center of the rotating member 2 to the magnetic field detector 3 is set, Both the distribution of the magnetic field strength and the distribution of the magnetic field strength in the X direction are substantially sinusoidal.
On the other hand, as can be seen from FIG. 10, when a radial anisotropic magnet is used as the rotating member 2, the distribution of the magnetic field strength becomes a sinusoidal shape as the distance from the center of the rotating member 2 to the magnetic field detector increases. Approached. However, when the distance from the center of the rotating member to the magnetic field detector was less than 14 mm, the magnetic field intensity distribution in the Z direction was a square wave. Further, in the case of less than 14 mm, the distribution of the magnetic field strength in the X direction has a triangular wave shape.

  FIG. 11 shows the amplitude of the Z direction magnetic field strength, the amplitude of the absolute value of the magnetic field strength in the X direction, and the amplitude of the Z direction magnetic field strength when the distance from the center of the rotating member 2 to the magnetic field detector 3 is changed. It is a figure which shows ratio (henceforth the ratio of magnetic field strength) with the amplitude of the magnetic field strength of a X direction. FIG. 11A is a diagram showing a result when a polar anisotropic magnet is used as the rotating member 2, and FIG. 11B shows a result when a radial anisotropic magnet is used as the rotating member 2. FIG.

  As can be seen from FIG. 11A, when a polar anisotropic magnet is used as the rotating member 2, the magnetic field strength ratio increases with an increase in the distance from the center of the rotating member 2 to the magnetic field detector 3. When the distance was 14 mm or more, the ratio of the magnetic field strengths was about 1.4 and became substantially constant. On the other hand, as can be seen from FIG. 11 (b), the case where a polar anisotropic magnet is used as the rotating member 2 also increases as the distance from the center of the rotating member 2 to the magnetic field detector increases. Is 16 mm or more, the magnetic field strength ratio is approximately 1.4, which is substantially constant.

  11A and 11B, when the distance from the center of the rotating member 2 to the magnetic field detecting unit 3 is increased from 11 mm to 14 mm, the polar anisotropic magnet is used as the rotating member 2. , The ratio of magnetic field strength increased slowly from about 1.2 to about 1.4. On the other hand, when a radial anisotropic magnet was used as the rotating member 2, the ratio of the magnetic field strength increased rapidly from about 0.6 to about 1.4. As described above, when the polar anisotropic magnet is used as the rotating member 2, the change in the ratio of the magnetic field strength is more gradual than that of the radial anisotropic magnet. The smaller the distance from the part 3, the more remarkable.

  FIG. 12 is a diagram illustrating the amount of change in the magnetic field angle around the rotating member when the distance from the center of the rotating member 2 to the magnetic field detection unit 3 is increased by 0.5 mm from a predetermined reference distance (mm). In addition, the value in a figure shows the distance (reference distance) before increasing. 12A shows the result when a polar anisotropic magnet is used for the rotating member 2, and FIG. 12B shows the result when a radial anisotropic magnet is used as the rotating member 2.

  As can be seen from FIG. 12, when a polar anisotropic magnet was used as the rotating member 2, the change amount of the magnetic field angle was less than 1.0 (deg) in all the results. On the other hand, when a radial anisotropic magnet is used as the rotating member 2, the amount of change in the magnetic field angle is larger than that in the case of the polar anisotropic magnet, and in particular, the amount of change in the magnetic field angle increases as the reference distance decreases. .

  By the way, as described above, in order to improve the linearity of the calculated value θ calculated by the calculation unit 4 with respect to the rotation angle, the magnetic field strength ratio and the sensitivity ratio of the magnetic field detection unit 3 are canceled out with each other. There is a case where correction processing is performed in which a sensitivity ratio of the detection unit 3 is set or a coefficient is applied to one of the magnetic field strengths so that the magnetic field strength ratio becomes 1. In this case, as shown in FIG. 11, by using a polar anisotropic magnet as the rotating member 2, even if the distance between the rotating member 2 and the magnetic field detector 3 changes, the ratio of the magnetic field strength hardly changes. Compared with the case where a radial anisotropic magnet is used, the above processing becomes easier. The difference in the ease of processing described above becomes remarkable particularly when the distance between the rotating member 2 and the magnetic field detector 3 is small.

  Further, as can be seen from the results of FIG. 12, by using polar anisotropic magnetism as the rotating member 2, the change in the direction of the magnetic field that occurs when the radial distance between the rotating member 2 and the magnetic field detector 3 fluctuates. Can be reduced. For this reason, the use of polar anisotropic magnets as the rotating member 2 can reduce fluctuations in the detection result due to the influence of the assembly error of the angle detection device. Moreover, even when the distance in the radial direction between the rotating member 2 and the magnetic field detecting unit 3 varies due to the shake of the rotating shaft when the angle detecting device is used, fluctuations in the detection result can be reduced. In particular, when the distance between the rotating member 2 and the magnetic field detection unit 3 is small, fluctuations in the detection result can be reduced by using a polar anisotropic magnet as the rotating member 2.

  FIG. 13 is a diagram illustrating linearity between the rotation angle of the rotating member 2 and the detection angle of the angle detection device at each rotation angle after the above correction processing is performed. In this figure, the correction coefficient is 1.6 when a polar anisotropic magnet is used as the rotating member 2 in this figure, and the correction coefficient when radial anisotropy is used is 20. It was 5. The distance between the center of the rotating member 2 and the magnetic field detector 3 was set to 12.5 mm. As a reference for linearity, a% FS value indicating a difference between an ideal straight line when the relation between the rotation angle of the rotating member 2 and the direction of the magnetic field at each rotation angle is linearly approximated and the actual relation is used. As shown in FIG. 13, excellent linearity was obtained when a polar anisotropic magnet was used as the rotating member 2. From this result, it was confirmed that the correction process is easier when a polar anisotropic magnet is used as the rotating member 2.

  As described above, by using a polar anisotropic magnet as the rotating member 2, it is possible to maintain the detection accuracy while reducing the size of the apparatus. As shown in FIG. 9, the magnetic field strength distribution of the polar anisotropic magnet is a sine wave. Therefore, the case where an isotropic magnet magnetized so that the magnetic flux density distribution on the surface facing the magnetic field detector 3 is a sine wave is used as the rotating member 2 as in the case of the polar anisotropic magnet. The effect of can be obtained. In general, isotropic magnets are cheaper than polar anisotropic magnets, and manufacturing costs can be reduced by using isotropic magnets as rotating members.

[Second Embodiment]
The second embodiment is another embodiment of the shape of the rotating member 2 in the first embodiment. As shown in FIG. 14, in this embodiment, a groove portion 21 extending in the circumferential direction is formed on the outer peripheral surface of the rotating member. The groove 21 is formed in the central portion of the outer peripheral surface of the rotating member 2 in the Y-axis direction (thrust direction) over the entire outer peripheral surface. In this embodiment, the groove part 21 has a substantially rectangular shape in a cross-sectional view in a direction perpendicular to the extending direction. In addition, the shape of the groove part 21 is not restricted to this, For example, shapes other than the above, such as circular arc shape, semicircle shape, triangular shape, step shape, may be sufficient.

  Next, the change in the relative position between the rotating member 2 and the magnetic field detecting unit 3 when the rotating member 2 having the groove 21 is used and when the groove 21 is not formed is the magnetic field angle detection result. A simulation result indicating the influence will be described. In the model used in the simulation, the rotating member 2 is a ring having an outer diameter of 10.3 mm (radius 5.15 mm), an inner diameter of 8.2 mm (radius 4.1 mm), and a thickness (thrust direction width) of 5.0 mm. It is assumed that the magnet is a magnet having four N pole regions N and S pole regions S arranged alternately at an equal pitch. The groove 21 has a width of 1 mm and a depth of 1 mm. The width is 0.5 mm from the center of the rotating member 2 in the thickness direction, and the thickness of the rotating member 2 and the center line in the width direction of the groove 21. It was arranged so that the center line of the direction coincided. The initial position of the magnetic field detection unit 3 was 12.5 mm from the center of the rotating member 2 in the radial direction, and the center in the thickness direction of the rotating member 2 at the thrust direction.

  FIG. 15 shows a simulation result when the rotating member 2 and the magnetic field detection unit 3 are displaced in the thrust direction. FIG. 15A is a diagram showing a result when the rotating member 2 having the groove portion 21 is used, and FIG. 15B is a diagram showing a result when the rotating member having no groove portion 21 is used. is there. In these figures, the amount of change in the magnetic field angle from the initial position when the magnetic field detection unit 3 at each rotation angle moves in the thrust direction from the initial position is shown as a% value. As can be seen from the figure, when the magnetic field detector is displaced by 1.5 mm, and when the groove 21 is not provided in the rotating member 2, the change amount of the magnetic field angle is 0.5% or more. On the other hand, when the groove portion 21 was formed in the rotating member 2, the amount of change in the magnetic field angle was 0.25% or less, and the amount of change was greatly reduced as compared to the case where the groove portion 21 was not formed. Thus, by forming the groove portion 21 in the rotating member 2, it is possible to prevent the detection result of the magnetic field detecting unit 3 from changing due to the relative position of the rotating member and the magnetic field detecting unit 3 changing in the thrust direction. Can do.

  FIG. 16 is a schematic diagram showing the distribution of the magnetic field strength in the thrust direction of the rotating member 2. FIG. 16A shows a case where the groove portion 21 is provided, and FIG. 16B shows a case where the groove portion 21 is not provided. When the groove portion 21 is not provided, the magnetic field intensity becomes maximum near the center portion, and decreases rapidly toward both ends. On the other hand, when the groove portion 21 is provided, the magnetic field strength in the vicinity of the central portion becomes small, so that the change in the magnetic field strength becomes small even if the position in the thrust direction changes.

  As described above, the magnetic field detection unit 3 detects the magnetic field angle by detecting the magnetic field strength in two directions, and the change in the magnetic field strength when the position of the magnetic field detection unit 3 in the thrust direction is changed. Different in direction. For this reason, it is considered that the detection result of the magnetic field angle changes when the magnetic field detection unit 3 moves in the thrust direction. Therefore, the amount of change in the detection result when the magnetic field detector 3 moves in the thrust direction can be reduced by forming the groove portion 21 in the rotating member and reducing the change in the magnetic field strength accompanying the change in position in the thrust direction. It is thought that was made. In addition, since the magnetic field intensity of the area | region in which the groove part 21 was formed becomes substantially constant, it is especially preferable to arrange | position both so that the magnetic field detection part 3 and the rotation member 2 may oppose in the formation area of the groove part 21.

  FIG. 17 shows a simulation result when the rotating member 2 and the magnetic field detector 3 are displaced in the radial direction. FIG. 17A is a diagram showing a result when the rotating member 2 in which the groove portion 21 is formed is used, and FIG. 17B is a diagram showing a result in the case where the rotating member without the groove portion 21 is used. It is. As in FIG. 15, the amount of change from the initial position is shown as a% value. As can be seen from the figure, when the magnetic field detector is displaced by 0.5 mm from the initial position, or when the groove 21 is not provided in the rotating member 2, the maximum value of the change amount of the magnetic field angle is about 0.5%. there were. On the other hand, when the groove portion 21 was formed on the rotating member 2, the maximum value of the change amount of the magnetic field angle was about 0.25%, and the change decreased compared to the case where the groove portion 21 was not formed. Thus, by forming the groove portion 21 in the rotating member 2, it is possible to prevent the detection result of the magnetic field detecting unit from changing due to the relative position of the rotating member and the magnetic field detecting unit 3 changing in the radial direction. it can.

  As described above, by forming the groove portion 21 on the outer peripheral surface of the rotating member 2, the influence on the detection result of the magnetic field detection unit 3 is reduced regardless of whether the position is shifted in the thrust direction or the radial direction. be able to.

[Third Embodiment]
The second embodiment is another embodiment of the arrangement configuration of the N-pole region 5 and the S-pole region 6 in the rotating member 2 in the first embodiment.
As shown in FIG. 18, in the N-pole region 5 and the S-pole region 6, the first direction (Z direction) in which the maximum magnetic field is obtained for the magnetic field generated around the rotating member 2 is parallel to the rotating member 2 rotation center. Are arranged as follows. The N pole region 5 and the S pole region 6 are provided on the lower surface portion of the rotating member 2. In a state where one N-pole region 5 is sandwiched between two S-pole regions 6, the N-pole regions 5 and the S-pole regions 6 are alternately arranged around the rotation center.

  The magnetic field detector 3 is arranged in a direction parallel to the rotation center of the rotating member 2 with respect to each of the N-pole region 5 and the S-pole region 6. The magnetic field detector 3 is arranged so as to overlap with the rotating member 2 in the vertical direction in the radial direction of the rotating member 2. In this way, the rotating member 2 is rotated on the substrate 7 provided with the magnetic field detector 3.

  In the second embodiment, the first direction (Z direction) in which the maximum magnetic field is obtained for the magnetic field generated around the rotating member 2 is the axial direction of the rotating member 2. A second direction (X direction) along the alignment direction of the N pole region 5 and the S pole region 6 is the rotation direction of the rotating member 2. The third direction (Y direction) is the radial direction of the rotating member 2.

[Another embodiment]
(1) In the first, second, and third embodiments, for example, the magnetic field detection unit 3 adds the output voltage of the pair of detection elements 9c and 9d arranged along the Y direction and the X direction. The magnitude of the magnetic field component in the Z direction can also be detected by obtaining an average value with the value obtained by adding the output voltages of the pair of detection elements 9a and 9b. As described above, the magnetic field detection unit 3 uses both the pair of detection elements 9c and 9d arranged along the Y direction and the pair of detection elements 9a and 9b arranged along the X direction. The size of the component can also be detected.

(2) In the first, second, and third embodiments, only one pair of the pair of detection elements 9a and 9b in which the pair of detection elements 9 are arranged along the X direction may be provided. In this case, the magnetic field detection unit 3 detects the magnitude of the magnetic field component in the Z direction by adding the output voltages of the pair of detection elements 9a and 9b arranged along the X direction, and arranges it along the X direction. The magnitude of the magnetic field component in the X direction is detected by calculating the difference between the output voltages of the pair of detection elements 9a and 9b.

(3) In the said 3rd Embodiment, the magnetic field detection part 3 can also be arrange | positioned in the radial direction outer side of the rotating member 2. FIG.

The perspective view and sectional drawing of the angle detection apparatus in 1st Embodiment Perspective view of magnetic field detector Cross section of magnetic field detector Graph showing the relationship between the external magnetic field and the maximum magnetization of the magnetic plate The figure which shows the angle of the applied magnetic field, and the graph which shows the relationship between the angle of the applied magnetic field and the magnetic field A graph showing the relationship between the rotation angle of the rotating member and the magnetic field strength Graph showing the relationship between the angle and the calculated value of the angle detector Schematic diagram showing the state of magnetic field lines in the rotating member Diagram showing the distribution of magnetic field strength when using a polar anisotropic magnet Diagram showing the distribution of magnetic field strength when a radial anisotropic magnet is used The figure which shows the relationship between the distance from a rotating member, and the ratio of magnetic field intensity The figure which shows the change of the magnetic field direction when the distance from a rotating member changes Diagram showing linearity between rotation angle and calculation angle The perspective view of the angle detection apparatus in 2nd Embodiment The figure which shows the change of the detection result when the position shifts in the thrust direction Schematic diagram showing the magnetic field distribution in the thrust direction of the rotating member The figure which shows the change of the detection result when the position shifts in the radial direction The perspective view and sectional drawing of the angle detection apparatus in 2nd Embodiment A perspective view and a sectional view of a conventional angle detection device A graph showing the relationship between the rotation angle of the rotating member and the magnetic field strength

Explanation of symbols

2 Rotating member 3 Magnetic field detection unit 4 Calculation means (calculation unit)
5 N-pole region 6 S-pole region 8 Magnetic plate 9 Detection element 21 Groove Z First direction X Second direction

Claims (11)

A rotating member in which N pole regions having N polarity and S pole regions having S polarity are alternately arranged around the rotation center;
A magnetic field detection unit having a plate-like magnetic plate and a pair of detection elements for detecting the magnitude of the magnetic field component in the direction perpendicular to the magnetic plate;
A calculation means for obtaining a rotation angle of the rotating member based on detection information of the magnetic field detection unit;
The magnetic field detector is disposed so as to face the magnetic plate perpendicularly to a first direction in which a maximum magnetic field is obtained with respect to a magnetic field generated around the rotating member, and the first direction and the N-pole region And an angle detection device configured to detect magnitudes of magnetic field components in two directions, that is, a second direction along an arrangement direction of the S pole region.   The angle detection device according to claim 1, wherein the N-pole region and the S-pole region are arranged so that the first direction and the second direction are orthogonal to each other.   The angle detection device according to claim 1, wherein the pair of detection elements are arranged along the second direction.   The pair of detection elements are provided in two sets, one set arranged along the second direction and one set arranged along the direction orthogonal to the second direction on a plane perpendicular to the first direction. The angle detection device according to any one of claims 1 to 3. The rotating member is arranged so that each of the N-pole region and the S-pole region faces radially outward,
The angle detection device according to any one of claims 1 to 4, wherein the magnetic field detection unit is disposed radially outward of the rotating member that faces the N-pole region and the S-pole region. . The N pole region and the S pole region are arranged such that the first direction is parallel to the rotation center,
The angle detection device according to claim 1, wherein the magnetic field detection unit is arranged in a direction parallel to the rotation center with respect to each of the N-pole region and the S-pole region.   The angle detection device according to any one of claims 1 to 6, wherein the N-pole region and the S-pole region are formed of an annular or circular polar anisotropic magnet.   The N-pole region and the S-pole region are formed of an annular or circular isotropic magnet that is magnetized so that the distribution of the magnetic field intensity on the surface facing the magnetic field detector is a sine wave. The angle detection device according to any one of claims 1 to 6.   The radial width of the magnet forming the N-pole region and the S-pole region is set to be larger than half the circumferential width of the N-pole region and half the circumferential width of the S-pole region. The angle detection device according to claim 7 or 8, wherein   The angle detection device according to any one of claims 1 to 9, wherein a groove portion extending in a circumferential direction is formed on an outer peripheral surface of a magnet that forms the N-pole region and the S-pole region.   The angle detection device according to claim 10, wherein the magnetic field detection unit and the magnet face each other in a region where the groove is formed in the rotation axis direction of the rotation member.

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