JP2009300262A - Displacement detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a displacement detector capable of surely detecting displacement of a moving object in an inexpensive and compact structure. <P>SOLUTION: The displacement detector includes a moving member 1 capable of rotary motion and linear motion in a direction along a rotation axis and including a cylindrical or arcuate magnetic pole region 2 parallel-magnetized in one direction along a plane having the rotation axis 10 as a normal line and having the rotation axis 10 as the center, a magnetic field detecting means 3 provided oppositely to the magnetic pole region 2 and capable of detecting magnitudes of magnetic field components in three directions orthogonal to one another including an X-axis extending along a radial direction of the magnetic pole region 2, a Y-axis extending along a rotation direction of the moving member 1 and a Z-axis extending along the rotation axis 10, and a calculating means 4 for obtaining a rotation angle and the displacement of the linear motion of the moving member 1 based on detection results from the magnetic field detecting means 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a displacement detection device that detects a rotation angle of a moving member and a displacement of linear movement along a rotation axis.

  A displacement detection device capable of detecting displacements in two different directions as described above is used, for example, in a position detection device for a shift lever of a vehicle. Some vehicle shift levers are displaced in two directions: a shift direction along the traveling direction of the vehicle and a select direction orthogonal to the shift direction. Therefore, for example, the position of the shift lever is detected by detecting the movement of the shift lever in the select direction as a rotation angle by the above-described displacement detection device and detecting the movement in the shift direction as a displacement of linear movement along the rotation axis. Is done. Conventionally, as this type of displacement detection device, for example, the one described in Patent Document 1 is known. This displacement detection device includes a semicircular magnet provided around the rotation shaft and a Hall element arranged around the rotation shaft. As a Hall element, a pair of Hall elements provided with a detection surface perpendicular to the rotation axis so as to detect the magnetic field intensity according to the displacement in the direction along the rotation axis of the magnet, and the magnetic field strength according to the rotation of the magnet are detected. And a pair of Hall elements having a detection surface perpendicular to the X axis. In this displacement detection device, based on the change of the magnetic field strength accompanying the rotation of the semicircular magnet and the linear movement along the rotation axis, the two-way position of the magnet rotation direction and the direction along the rotation axis is detected. The

JP-T-2002-530666 (paragraphs 0041 to 0046 and FIGS. 5 to 7)

  However, in the above-described displacement detection device, it is necessary to arrange the Hall element for detecting the position in the rotation direction and the Hall element for detecting the direction along the rotation axis in different directions and arrangement locations. . For this reason, the number of parts has increased, which has been a cause of cost increase. Furthermore, it is necessary to secure a space for arranging the Hall element for each detection direction, and 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 displacement detection device that can reliably detect the displacement of a moving member while taking a compact configuration at a low cost.

  The first characteristic configuration of the present invention is capable of rotational movement and linear movement in a direction along the rotational axis of the rotational movement, and is parallel magnetized in one direction along a plane having the rotational axis as a normal line. A moving member having a cylindrical or arc-shaped magnetic pole region with the rotation axis as the center, and an X-axis along the radial direction of the magnetic pole region provided in opposition to the magnetic pole region, in the rotational direction of the moving member A magnetic field detecting means capable of detecting magnitudes of magnetic field components in three directions perpendicular to each other along the Y axis along the Z axis along the rotation axis, and based on a detection result of the magnetic field detecting means, An arithmetic means for obtaining a rotation angle and a displacement of the linear movement is provided.

If a cylindrical or arc-shaped magnetic pole region centered around the rotation axis is provided in parallel in one direction along the plane having the rotation axis as a normal line as in this configuration, the XY of the magnetic field around the magnetic pole region is provided. The direction of the component along the plane changes corresponding to the rotational direction position of the moving member, and the component along the XY plane of the magnetic field rotates once in one turn. Moreover, the component of the direction along the XZ plane of the magnetic field changes in the direction along the rotation axis as it is displaced from the central portion of the magnetic field region in the direction along the rotation axis. Thus, the three-dimensional direction of the magnetic field is uniquely determined according to the combination of the displacement in the rotational direction of the moving member and the displacement in the direction along the rotational axis. Therefore, by detecting the magnitudes of the magnetic field components in the three directions, it is possible to detect the displacement in the two directions of the moving member along the rotation direction and the direction along the rotation axis.
As described above, since the three-dimensional direction of the magnetic field that is uniquely determined is measured, it is not necessary to provide a plurality of magnetic field detection units as in the prior art in order to detect displacement in two directions of the moving member. As a result, it is possible to obtain a displacement detection device that can reliably detect the displacement of the moving body while adopting a low-cost and compact configuration.

  According to a second characteristic configuration of the present invention, the calculation means 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 the space vector is expressed as an XY plane. The rotation angle is obtained based on the direction of the projection vector in the XY plane when projected onto the XZ plane, and based on the direction of the projection vector in the XZ plane when the space vector is projected onto the XZ plane. The point is to obtain the displacement of the linear movement.

  As described above, the direction of the component along the XY plane of the magnetic field changes corresponding to the rotational direction position of the moving member, and the direction component of the magnetic field along the XZ plane depends on the position in the direction along the rotational axis. Change. Accordingly, the rotation angle is determined based on the direction of the projection vector in the XY plane of the magnetic field, and the displacement in the direction along the rotation axis is determined based on the direction of the projection vector in the XZ plane of the magnetic field. The displacement can be easily obtained.

DESCRIPTION OF EMBODIMENTS An embodiment of a displacement detection device according to the present invention will be described based on the drawings.
As shown in FIG. 1, the displacement detection device is based on a moving member 1, a magnetic field detection device 3 as a magnetic field detection unit that detects a magnetic field generated around the moving member 1, and detection information of the magnetic field detection device 3. And a computing unit 4 as computing means for obtaining the displacement of the moving member 1 relative to the magnetic field detecting device 3.

  As shown in FIGS. 1, 2, and 3, the moving member 1 can be displaced in two directions: a rotational displacement about the rotation shaft 10 and a linear displacement along the rotation shaft 10. As shown in FIG. 2, the moving member 1 is provided with a ring-shaped magnet 2 that forms a magnetic field region so as to be able to move integrally with the moving member 1. In this embodiment, the magnet 2 is magnetized in parallel so that the direction of the magnetic field in the magnet 2 is a plane along the rotation axis 10 as a normal line, that is, one direction along the XY plane.

As shown in FIGS. 1 and 4, the magnetic field detection device 3 includes an X axis along the radial direction of the magnet 2 (magnetic field region), a Y axis along the rotation direction of the moving member 1, and an axis of the rotation shaft 10. The magnitudes of magnetic field components in three directions perpendicular to each other on the Z axis along the direction can be detected.
The magnetic field detection device 3 is, for example, a Hall IC, and specifically, an MLX90333 manufactured by Melexis can be used.
The magnetic field detection device 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 Y axis and a pair of detection elements 9c and 9d arranged along the Z axis.

The detection principle of the magnetic field detection device 3 will be described with reference to FIG.
The magnetic field component in the X direction is detected as follows. That is, as shown in FIG. 5A, when an external magnetic field is applied in the X direction, a magnetic field component along the X direction is generated in the pair of detection elements 9c and 9d arranged along the Z 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 the magnetic field component in the X direction is detected, the magnetic field component in the Z direction is removed as follows. That is, as shown in FIG. 5B, when a magnetic field is applied in the Z 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. Accordingly, the magnetic field component in the Z direction can be removed by calculating the sum of the output voltages of the pair of detection elements 9c and 9d.

  On the other hand, the magnetic field component in the Z direction is detected as follows. That is, as shown in FIG. 5B, when a magnetic field component in the Z 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 Z direction includes A magnetic field component in the X direction perpendicular to the magnetic plate 8 is generated. At this time, the magnitude of the magnetic field component in the X 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, the magnetic field component proportional to the magnitude of the external magnetic field in the Z direction can be detected by calculating the difference between the output voltages of the pair of detection elements 9c and 9d.

  When the magnetic field component in the Z direction is detected, the magnetic field component in the X direction is removed as follows. That is, as described above, when a magnetic field is applied in the X direction, a magnetic field component along the X direction is generated in the pair of detection elements 9c and 9d. 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 X direction can be removed by calculating the difference between the output voltages of the pair of detection elements 9c and 9d.

  When a magnetic field component in the Y direction is applied, a magnetic field component in the X direction perpendicular to the magnetic plate 8 is generated in the same manner as when the magnetic field component in the Z direction is applied. Therefore, the magnetic field detection device 3 can detect the magnitude of the magnetic field component in the Y direction by calculating the difference between the output voltages of the pair of detection elements 9a and 9b arranged along the Y direction.

Next, calculation by the calculation unit 4 will be described.
The calculation unit 4 rotates based on the rotational axis θ of the moving member 1 around the rotation axis 10 based on the magnetic field component in the X direction, the magnetic field component in the Y direction, and the magnetic field component in the Z direction detected by the magnetic field detection device 3 (see FIG. 2) and a linear displacement Z (see FIG. 3) along the rotation axis 10 of the moving member 1 are calculated.

  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. When the space vector V is projected onto the XY plane, the direction of the projection vector V ′ in the XY plane (the angle α formed with the X axis of the projection vector V ′) and the space vector V are projected onto the XZ plane. The displacement of the moving member 1 is detected based on the direction of the projection vector V ″ in the XZ plane (the angle β formed with the X axis of the projection vector V ″).

  FIG. 7 shows simulation results when the moving member 1 is rotated around the rotation axis 10 at various Z-direction positions of the moving member 1. In this simulation, the moving member is a ring-shaped magnet 2 having an inner diameter of 16 mm, an outer diameter of 20 mm, and a height (thickness) of 10 mm, and is in one direction along the plane having the rotation axis 10 as a normal line, that is, XY. It was assumed that the magnet was parallel magnetized in one direction on a plane parallel to the plane. In this simulation, the Z-direction position is determined by moving the central portion in the height direction (thickness direction) of the moving member 1 at Z = 0 and moving at various Z-direction positions from Z = −3.5 mm to Z = 3.5 mm A correlation between the rotation angle θ of the member 1 and the angle α formed by the projection vector V ′ was obtained. The curve in the figure shows the angle α formed by the rotation angle θ of the moving member 1 and the projection vector V ′ when the position of the moving member 1 in the Z direction is changed in the range of Z = −3.5 mm to Z = 3.5 mm. Shows the range of fluctuation of correlation. As is apparent from FIG. 7, the correlation between the rotation angle θ of the moving member 1 and the angle α formed by the projection vector V ′ is substantially the same regardless of the position of the moving member in the Z direction.

  FIG. 8 shows simulation results when the moving member 1 is moved along the axis of the rotating shaft 10 at various rotational angles θ. In this simulation, the same ring-shaped magnet 2 as described above was assumed. Further, in this simulation, the angle β formed by the Z-direction position of the moving member 1 and the X axis of the projection vector V ″ when the rotation angle θ of the moving member 1 is varied in the range of θ = −50 deg to θ = + 50 deg. The correlation with was obtained. The curve in the figure shows the fluctuation range of the correlation with the angle β that is the Z-direction position of the moving member 1 when the rotation angle θ of the moving member 1 is varied in the range of θ = −50 deg to θ = + 50 deg. . As is clear from FIG. 8, the correlation with the angle β formed with the position of the moving member 1 in the Z direction is substantially the same regardless of the rotation angle θ.

As described above, the correlation between the rotation angle θ and the angle α of the moving member 1 and the correlation between the Z-direction position of the moving member 1 and the angle β can be obtained independently and accurately. Therefore, the calculation unit 4 can calculate the rotation angle of the moving body based on the angle α, and can calculate the displacement of the linear movement based on the angle β. Specifically, the calculation unit 4 calculates the angle α by the following formula based on the magnetic field component Bx in the X direction and the magnetic field component By in the Y direction.
[Formula 1]
α = arctan (By / Bx)
Further, based on the magnetic field component Bx in the X direction and the magnetic field component Bz in the Z direction, the angle β is calculated by the following formula.
[Formula 2]
β = arctan (Bz / Bx)

  Based on the calculated angle α, the rotation angle θ of the moving member 4 (see FIG. 2) is detected. Further, based on the angle β, the movement displacement Z (see FIG. 3) of the moving member 4 along the rotation axis 10 is detected. Thereby, the displacement of the moving member 2 in two directions is detected.

  As described above, since the three-dimensional direction of the magnetic field that is uniquely determined is measured, it is not necessary to provide a plurality of magnetic field detection devices 3 as in the prior art in order to detect the displacement of the moving member 1 in two directions. For this reason, the displacement detection apparatus which can detect the displacement of a moving member reliably can be obtained, taking a low-cost and compact structure.

  In the correlation shown in FIGS. 7 and 8, although a good correlation is obtained as described above, the correlation is not a linear relationship. This is because the intensity ratio of Bx and By or Bx and Bz is not 1: 1, and the intensity of Bx is larger than By and Bz. Therefore, the calculation unit 4 may perform correction by multiplying By and Bz by a coefficient k corresponding to the intensity ratio so that the corrected intensity ratio approaches 1: 1.

In this case, the calculation unit 4 calculates α and β based on the following equations.
[Formula 3]
α = arctan (kBy / Bx)
[Formula 4]
β = arctan (kBz / Bx)

  FIG. 9 shows the correlation between the rotation angle θ and the angle α of the moving member 1 when k = 2.2. Similarly to FIG. 7, the result of changing the position of the moving member 1 in the Z direction in the range of Z = −3.5 mm to Z = 3.5 mm is shown. As is apparent from FIG. 9, by performing such correction, the linearity of the line indicating the correlation is improved. FIG. 10 shows the correlation between the position of the moving member in the Z direction and the angle β when k = 2.5. Similarly to FIG. 8, the result when the rotation angle θ of the moving member 1 is varied in the range of θ = −50 deg to θ = + 50 deg is shown. As is apparent from FIG. 10, by performing such correction, the linearity of the line indicating the correlation is improved. As described above, in any case of the rotation angle and the position in the Z direction, the linearity of the line indicating the correlation is improved by the above correction. Therefore, the above-described correction further improves the accuracy of detecting the displacement of the moving member.

  The above-described displacement detection device is not particularly limited. For example, the displacement detection device is applied to a lever position detection device that detects a shift direction displacement of the shift lever of the vehicle along the vehicle traveling direction and a select direction displacement orthogonal to the shift direction. be able to.

[Another embodiment]
(1) In the above-described embodiment, the case where the ring-shaped magnet 2 is used as the magnet 2 forming the magnetic field region has been described as an example. However, the present invention is not limited to this. For example, an arc-shaped magnet 2 such as a half-ring shaped magnet 2 as shown in FIG. 11 may be used.

(2) In the above-described embodiment, the example in which the magnetic field detection device 3 is arranged so that the detection elements 9a and 9b are along the Y-axis direction and the detection elements 9c and 9d are along the Z-axis direction has been described. It is not limited to. For example, arrangements other than those described above may be employed such that the detection elements 9a and 9b are along the X direction and the detection elements 9c and 9d are along the Y direction.

The perspective view which shows the displacement detection apparatus which concerns on this invention Sectional drawing which shows the displacement detection apparatus which concerns on this invention The side view which shows the displacement detection apparatus which concerns on this invention 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 the simulation result at the time of rotationally displacing a moving member The figure which shows the simulation result at the time of moving a moving member linearly The figure which shows the simulation result which rotationally displaced the moving member at the time of correcting magnetic field intensity The figure which shows the simulation result which carried out the linear displacement of the moving member at the time of correcting magnetic field intensity The figure which shows another embodiment of the displacement detection apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Moving member 2 Magnet 3 Magnetic field detection apparatus 4 Operation part V Space vector V 'Projection vector V''Projection vector

Claims (2)

A rotational movement and a linear movement in the direction along the rotational axis of the rotational movement are possible, and the magnet is parallel magnetized in one direction along a plane with the rotational axis as a normal line, and is cylindrical or centered on the rotational axis. A moving member having an arc-shaped magnetic pole region;
Three directions orthogonal to the magnetic pole region, the X axis along the radial direction of the magnetic pole region, the Y axis along the rotational direction of the moving member, and the Z axis along the rotational axis. Magnetic field detection means capable of detecting the magnitude of the magnetic field component of
A displacement detection apparatus comprising: a calculation means for obtaining a rotation angle of the moving member and a displacement of the linear movement based on a detection result of the magnetic field detection means.   Assuming 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, the calculation means assumes a space vector in the XY plane when projected on the XY plane. The rotation angle is obtained based on the direction of the projection vector at, and the displacement of the linear movement is obtained based on the direction of the projection vector in the XZ plane when the space vector is projected onto the XZ plane. The displacement detection device described.

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