JP2009109274A - Rotation angle detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation angle detection device capable of detecting a rotation angle of a plurality of rotations with an inexpensive and compact constitution. <P>SOLUTION: The rotation angle detection device 1 for detecting a rotation angle of a rotator 5 includes a magnet 2; and a magnetic field detection means 3 capable of detecting the magnitude of a magnetic field component in mutually-orthogonal three directions, namely, an X-axis, a Y-axis and a Z-axis. The device 1 has a constitution wherein the magnet 2 or the magnetic field detection means 3 is circulated around a circulation axis in parallel with the Z-axis following rotation of the rotator 5, and a Z-axis component of relative displacement between the magnet 2 and the magnetic field detection means 3 is increased/decreased corresponding to circulation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a rotation angle detection device that detects the rotation angle of a rotating body, and is a magnetic field detection means capable of detecting the magnitude of a magnetic field component in three directions of X axis, Y axis, and Z axis orthogonal to each other. And a rotation angle device.

The rotation angle detection device as described above is used, for example, as a seat position detection device for an electric slide seat device of an automobile.
This type of slide sheet position detection device detects the rotation of a motor driving the slide sheet or the rotation of a drive shaft in conjunction with the rotation of the motor, and detects the position of the slide sheet from this rotation angle.
Normally, in this type of electric slide device, the motor and the drive shaft rotate a plurality of times when the seat slides. For this reason, the position detection device needs to detect the number of rotations and the rotation angle of the rotating body that rotates a plurality of times.

  Conventionally, as such a seat position detecting device, the number of rotations of a motor is detected by measuring a pulse signal generated along with the rotation of the motor with an in-vehicle computer unit or the like, and the position of the seat is determined from the number of rotations of the motor. What you want is known.

  As a rotation angle detection device capable of detecting a plurality of rotation angles so as to be applicable to the sheet position detection device, a rotation angle detection device described in Patent Document 1 is known. The rotation angle detection device includes: a rotation conversion mechanism that converts rotation of a rotating body that is a detection target of a rotation angle into rotation of a detection shaft having different rotation speeds by two transmissions having different transmission gear ratios; Magnetic field generating means provided on the detection axis and having circumferential anisotropy around the rotation center. Corresponding to each magnetic field generating means, magnetic field detecting means for detecting the rotation angle of the magnetic field generating means is provided. Based on the difference between the rotation angles detected by these two magnetic field detection means, the rotation angle of rotation is calculated.

Japanese Laid-Open Patent Publication No. 2007-78552 (paragraph 0005 and FIG. 2)

  However, in the method of detecting the position of the slide sheet by measuring the pulse signal generated along with the rotation of the motor, it is necessary to store the rotation speed of the motor in a computer unit or the like. For this reason, for example, when the slide sheet is moved in a state where the power of the computer unit is turned off, the movement amount is not stored, and there is a problem that an accurate position cannot be detected.

  In addition, since the rotation angle detection device described in Patent Document 1 can detect the rotation angle of the rotating body itself, although the above-mentioned problem does not occur, it is essential to provide two magnetic field detection means and the cost increases. There was a problem to do. In addition, since two detection axes must be provided, there is a problem that it is difficult to make the apparatus compact.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a rotation angle detection device capable of detecting a plurality of rotation angles while taking a compact configuration at a low cost.

  A first characteristic configuration of the present invention is a rotation angle detection device that detects a rotation angle of a rotating body, and detects the magnitude of a magnetic field component in three directions of an X axis, a Y axis, and a Z axis orthogonal to each other. A magnetic field detection means capable of rotating around the rotation axis parallel to the Z axis as the rotating body rotates, and the magnet or the magnetic field detection means according to the rotation. The Z-axis component of the relative displacement of the magnetic field detection means is configured to increase or decrease.

According to this configuration, as the rotating body rotates, the magnet or the magnetic field detection means circulates around the rotation axis parallel to the Z axis, and the Z axis of the relative displacement between the magnet and the magnetic field detection means according to the rotation. Since the components increase and decrease, even when the magnet or the magnetic field detection means circulates a plurality of times, the relative positional relationship with each other is uniquely determined. For this reason, the three-dimensional direction of the magnetic field is uniquely determined, and the rotation angle of the rotating body is detected by detecting the magnitude of the magnetic field components in the three directions of the X axis, the Y axis, and the Z axis orthogonal to each other by the magnetic field detection means Can be detected.
Further, since the three-dimensional direction of the magnetic field that is uniquely determined is measured, there is no need to provide a plurality of magnetic field detection means as in the prior art in order to detect the number of rotations of the rotating body.
Furthermore, since the magnet or the magnetic field detection means circulates around the rotation axis parallel to the Z axis, the Z axis component of the relative displacement of the magnet and the magnetic field detection means may be increased or decreased according to the rotation. There is no need to provide a plurality of detection axes as in the prior art.
As a result, it is possible to obtain a rotation angle detection device capable of detecting a plurality of rotation angles while taking a low-cost and compact configuration.

  The second characteristic configuration of the present invention resides in that the rotation axis coincides with the Z axis.

As in this configuration, the center of the combined vector of the magnetic field component in the X-axis direction and the magnetic field component in the Y-axis direction when the magnet or the magnetic field detecting means circulates is fixed by matching the rotation axis and the Z-axis. , Magnetic field detection becomes easier.
Further, since the magnetic field detecting means is located on the extension line of the rotation axis, the width in the direction perpendicular to the rotation axis can be reduced, and the apparatus can be made more compact.

  According to a third characteristic configuration of the present invention, the locus of relative movement between the magnet and the magnetic field detecting means is a spiral shape having the same orbiting radius when viewed in the orbiting axis direction.

  With this configuration, the magnitude of the combined vector of the magnetic field component in the X-axis direction and the magnetic field component in the Y-axis direction when the magnet or the magnetic field detection means circulates becomes constant, so that the rotation angle can be detected more accurately. .

A fourth characteristic configuration of the present invention assumes a space vector in a three-dimensional space of the magnetic field starting from the origin of the X axis, the Y axis, and the Z axis, and projects the space vector onto the XY plane. The rotation angle is detected based on the direction of the projection vector in the XY plane and the angle formed by the space vector and the projection vector.

  When the magnet and the magnetic field detection means are relatively displaced as described above, the direction of the projection vector changes at the same period as the rotation of the magnet, and the angle between the space vector and the projection vector moves along the rotation axis of the magnet. It changes with. Accordingly, the relative movement between the magnet and the magnetic field detection means can be detected based on the direction of the projection vector and the angle formed between the space vector and the projection vector, and the rotation angle can be detected reliably.

An embodiment of a rotation angle detection device 1 according to the present invention will be described with reference to the drawings. FIG. 1 is a plan view of the vehicle slide seat device S viewed from the floor side of the vehicle. The rotation angle detection device 1 of the present invention is used, for example, for position detection of the slide seat 14 of the vehicle slide seat device S. Here, the rotation angle of the drive shaft 11 is detected.
In the vehicle slide seat device S, the slide seat 14 slides on the rail 13. The drive shaft 11 is driven via a motor 10 and a speed reduction mechanism. The rotational power of the drive shaft 11 is converted into power in the sliding direction by the orthogonal conversion unit 12 and transmitted to the slide member fixed to the slide sheet 14.

The drive shaft 11 is provided with the rotation angle detection device 1, and the position of the slide sheet 14 is detected based on the rotation angle of the drive shaft 11 (corresponding to the rotating body 5 of the present invention).
Normally, in such a vehicular slide seat device S, when the slide seat 14 is slid over the entire slide range, the drive shaft 11 rotates a plurality of times. Therefore, the rotation angle detecting device 1 needs to detect a plurality of rotation angles. Hereinafter, such a rotation angle detection device 1 will be described.

As shown in FIGS. 2 and 3, the rotation angle detection device 1 includes a rotation shaft 4, a gear 6 that is externally fitted to the rotation shaft 4 so as to be integrally rotatable, a magnet 2 that is fixed to the gear 6, and a gear. 6 and a magnetic field detection means 3 provided to face the 6.

In the present embodiment, the magnet 2 is arranged offset from the axis of the rotating shaft 4, and the magnetic field detecting means 3 is fixedly arranged on an extension line of the axis of the rotating shaft 4. The rotating shaft 4 is formed with a threaded portion 4a, and the rotating shaft 4 is configured to move in the thrust direction (Z-axis direction) as the rotating shaft 4 rotates.
The gear 6 meshes with a gear 7 that is externally fitted to the rotating body 5 whose rotation angle is to be detected. In this embodiment, the gear 6 and the gear 7 are set so that the rotation of the rotating body 5 is decelerated and transmitted to the rotating shaft 4. Therefore, the rotation angle (number of rotations) of the rotating body 5 larger than the maximum value of the rotation angle (number of rotations) of the rotating shaft 4 can be detected.
With the above configuration, as shown in FIG. 2, the rotating shaft 4 rotates and moves in the thrust direction as the rotating body 5 rotates.
Thereby, the magnet 2 circulates around the rotation axis, and the component in the Z-axis direction of the relative displacement between the magnet 2 and the magnetic field detection means 3 increases or decreases according to the rotation. Specifically, as shown in FIG. 7, the magnet 2 moves while drawing a spiral trajectory about the rotation axis 4 (Z axis).

As shown in FIGS. 4 and 6, the magnetic field detection means 3 is configured to be able to detect magnetic fields in three directions of X axis, Y axis, and Z axis that are orthogonal to each other.
The magnetic field detection means 3 is, for example, a Hall IC, and specifically, MLX90333 manufactured by Melexis Corporation can be used.
The magnetic field detection means 3 includes a magnetic plate 8 and a detection element 9 that detects a magnetic field. The magnetic plate 8 is formed in a disc shape. The detection element 9 (Hall element) is disposed immediately below the end of the magnetic plate 8. The detection element 9 is provided with two pairs of a pair of detection elements 9a and 9b arranged along the X axis and a pair of detection elements 9c and 9d arranged along the Y axis.
Here, the magnetic field detection means 3 is arranged so that the XY plane faces the magnet 2 and the Z axis coincides with the axis of the rotation shaft 4. The axis of the rotating shaft 4 corresponds to the rotating shaft of the present invention.

The detection principle of the magnetic field detection means 3 will be described with reference to FIG.
The magnetic field component in the Y-axis direction is detected as follows. That is, as shown in FIG. 5B, when a magnetic field component in the Y-axis direction is applied, the magnetic flux is bent by the magnetic plate 8, and the pair of detection elements 9c and 9d arranged along the Y-axis direction is applied. Generates a magnetic field component in the Z-axis direction perpendicular to the magnetic plate 8. 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.

  When a magnetic field component in the X-axis direction is applied, a magnetic field component in the Z-axis direction perpendicular to the magnetic plate 8 is generated in the same manner as when a magnetic field component in the Y-axis direction is applied. Therefore, the magnetic field detection means 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 detecting the magnetic field component in the Y-axis direction, the magnetic field component in the Z-axis direction is removed as follows. As shown in FIG. 5A, when a magnetic field component in the Z-axis direction is applied, 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. Will occur. 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 magnetic field component in the Z direction can be removed by calculating the difference between the output voltages of the pair of detection elements 9c and 9d.
Similarly, when the magnetic field component in the X-axis direction is detected, the magnetic field component in the Z direction can be removed by calculating the difference between the output voltages of the pair of detection elements 9a and 9b.

  On the other hand, the magnetic field component in the Z-axis direction is detected as follows. That is, as described above, when a magnetic field component in the Z-axis direction is applied, the directions of the magnetic field components generated in the pair of detection elements 9c and 9d arranged along the Y direction are the same. Therefore, the magnetic field detection means 3 can detect the magnitude of the magnetic field component in the Z-axis direction by calculating the sum of the output voltages of the pair of detection elements 9c and 9d arranged along the Y-axis direction.

  When detecting the magnetic field component in the Z-axis direction, the magnetic field component in the Y-axis direction is removed as follows. That is, as described above, when a magnetic field component in the Y-axis direction is applied, the direction of the generated magnetic field component is opposite between the pair of detection elements 9c and 9d arranged along the Y direction. Therefore, the magnetic field component in the Y-axis direction can be removed by calculating the sum of the output voltages of the pair of detection elements 9c and 9d.

Next, calculation by the calculation means will be described.
The calculation means calculates the rotation angle of the rotary shaft 4 based on the magnetic field component Bx in the X-axis direction, the magnetic field component By in the Y-axis direction, and the magnetic field component Bz in the Z-axis direction detected by the magnetic field detection means 3. Further, the calculation means calculates the rotation angle of the rotating body 5 based on a preset gear ratio between the rotating shaft 4 and the rotating body 5.

  In this embodiment, as shown in FIG. 6, a space vector V in a three-dimensional space of a magnetic field starting from the origin of the X axis, the Y axis, and the Z axis is assumed. Then, based on the direction of the projection vector V ′ (projection vector rotation angle α) in the XY plane when the space vector V is projected onto the XY plane, and the angle β formed by the space vector V and the projection vector V ′. The rotation angle is detected.

FIG. 8 shows a simulation result when the magnet 2 is spirally moved in the direction away from the magnetic field detection means 3 around the Z axis.
In FIG. 8, ♦ indicates a change in the rotation angle α accompanying the rotation of the rotation shaft 4, and ■ indicates a change in the angle β formed by the rotation of the rotation shaft 4.

The rotation angle α periodically changed at a period of 360 ° of the rotation angle of the rotary shaft 4. On the other hand, the angle β formed continuously increased as the rotation angle of the rotary shaft 4 increased.
That is, as shown in FIG. 7, when the rotation shaft 4 makes one rotation (360 ° rotation), the magnet 2 makes one rotation and returns to the original position in the direction along the XY plane, that is, as viewed in the Z-axis direction. The rotation angle α also returns to the original value. On the other hand, as shown in FIG. 9, when the Z-axis direction component of the distance between the magnet 2 and the magnetic field detection means 3 increases, the angle β formed increases.

  Therefore, the calculation means can calculate the rotation angle of the rotation shaft 4 based on the rotation angle α and the formed angle β. That is, a rotation angle during one rotation (a portion smaller than 360 ° of the rotation angle) is detected based on the rotation angle α, and the number of rotations (a portion of the rotation angle that is an integral multiple of 360 °) is determined based on the angle β formed. To detect. Thus, a rotation angle larger than 360 ° can be calculated based on the rotation angle α and the angle β formed.

Specifically, the calculation means calculates the angle α by the following formula based on the magnetic field component Bx in the X-axis direction and the magnetic field component By in the Y-axis direction.
[Formula 1]
α = arctan (By / Bx)
Further, β is calculated by the following expression based on the magnetic field component Bx in the X-axis direction, the magnetic field component By in the Y-axis direction, and the magnetic field component Bz in the Z-axis direction.
[Formula 2]
β = arctan [Bz / √ (Bx ² + By ² )]
Then, the rotation angle of the rotation shaft 4 is detected based on the calculated α and β, and the rotation angle of the rotation body 5 is detected based on the gear ratio between the rotation body 5 and the rotation shaft 4.

With the above-described configuration, the direction of the magnetic field with respect to the rotation angle of the rotator 5 (in this embodiment, the rotation angle α and the angle β formed) is uniquely determined. Therefore, a rotation angle of 360 ° or more can be detected without storing the number of rotations in a computer unit or the like as in the prior art.
Further, it is not necessary to provide a plurality of magnetic field detection means 3 as in the prior art in order to detect the rotation angle. For this reason, the cost of an apparatus can be reduced.

[Another embodiment 1]
In the above-described embodiment, the rotation of the rotating body 5 is transmitted to the rotating shaft 4 through the gears 6 and 7. However, the magnet 2 may be provided so as to be able to rotate integrally with the rotating body 5 and the rotation angle of the rotating body 5 may be directly detected.
By configuring the rotation angle detection device 1 in this way, the gears 6 and 7 are not interposed, and therefore the influence of backlash of the gears 6 and 7 can be removed and the rotation angle can be detected more accurately.

  In addition, as shown in FIG. 10, a plurality of gears 6, 7 a, 7 b, and 7 c may be interposed between the rotating body 5 and the rotating shaft 4. By configuring in this way, the gear ratio between the rotating body 5 and the rotating shaft 4 can be appropriately set according to the maximum value (number of rotations) of the rotating angle of the rotating body 5.

[Another embodiment 2]
In the above-described embodiment, the example in which the single magnetic field detection unit 3 is provided so as to face the magnet 2 has been described. However, for example, the magnetic field detection unit 3 may be disposed on both sides of the magnet 2.
By comprising in this way, the precision of an apparatus can be raised by detecting a rotation angle based on the magnetic field detection means 3 with the nearer distance with the magnet 2, for example.

[Another embodiment 3]
In the above-described embodiment, the example in which the magnetic field detection unit 3 is a fixed-side member and the magnet 2 moves as the rotating body 5 rotates is described. However, the rotation of the rotating body 5 is performed using the magnet 2 as the fixed-side member. Accordingly, the magnetic field detection means 3 may be configured to move.

The figure which shows the example of application of the rotation angle detection apparatus which concerns on this invention The figure which shows the rotation angle detection apparatus which concerns on this invention III-III sectional view of FIG. The figure which shows an example of a magnetic field detection apparatus Diagram showing the principle of detecting magnetic field components in each direction The figure which shows an example of the calculation by a calculating means The figure which shows an example of the locus | trajectory of relative movement with a magnet and a magnetic field detection means The figure which shows the simulation result at the time of moving a magnet spirally The figure which shows the change of a magnetic field when the displacement of the axial direction component of a magnet and a magnetic field detection means increases / decreases The figure which shows the rotation angle detection apparatus which concerns on another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotation angle detector 2 Magnet 3 Magnetic field detection means 5 Rotating body V Space vector V 'Projection vector

Claims (4)

A rotation angle detection device for detecting a rotation angle of a rotating body,
A magnet and magnetic field detection means capable of detecting the magnitude of magnetic field components in three directions of X axis, Y axis, and Z axis perpendicular to each other;
Along with the rotation of the rotating body, the magnet or the magnetic field detection means circulates around a rotation axis parallel to the Z axis, and Z of relative displacement between the magnet and the magnetic field detection means according to the rotation. A rotation angle detection device configured to increase or decrease an axial component.   The rotation angle detection device according to claim 1, wherein the rotation axis coincides with the Z axis.   The rotation angle detection device according to claim 1 or 2, wherein a trajectory of relative movement between the magnet and the magnetic field detection means is a spiral having an equal rotation radius when viewed in the rotation axis direction.   Assuming a space vector in the three-dimensional space of the magnetic field starting from the origin of the X axis, the Y axis, and the Z axis, the direction of the projection vector in the XY plane when the space vector is projected onto the XY plane The rotation angle detection device according to any one of claims 1 to 3, wherein the rotation angle is detected based on an angle formed between the space vector and the projection vector.

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