JP2009288158A - Rotation angle detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation angle detecting device which is hardly affected by a disturbance magnetic field from an arbitrary direction or, in other words, has a high degree of detection accuracy. <P>SOLUTION: The rotation angle detecting device includes a rotating body 4 to be detected which has N-pole and S-pole regions provided alternately around a rotation axis R, a plate-shaped magnetic substance 6 which is fixed at a position opposite to a plane of rotation formed by the N-pole and S-pole regions, and a magnetism detecting element 8 which is disposed between the rotating body 4 to be detected and the magnetic substance 6. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a rotation angle detection comprising a detected rotating body in which an N-pole region and an S-pole region are alternately provided around a rotation axis, and a magnetic detection element arranged to face the detected rotating body. Relates to the device.

  As prior art document information related to this type of rotation angle detection device, there is Patent Document 1 shown below. The rotation angle detection device described in Patent Document 1 is arranged such that the N-pole region and the S-pole region face the radially outer side of the detected rotating body. A plate-like magnetic body facing the rotating outer peripheral surface by the pole region and four Hall elements (magnetic detection elements) spaced apart from each other are provided near the back surface of the plate-like magnetic body. Here, the radially outer side of the detected rotating body coincides with the first direction in which the maximum magnetic field generated by the N-pole region or the S-pole region is obtained. The four Hall elements are arranged along the second direction (perpendicular to the first direction), which is the direction of rotation of the outer peripheral surface of the rotating body to be detected, and is the arrangement direction of the N-pole region and the S-pole region. A first pair of Hall elements and a third direction (perpendicular to the first direction and the second direction) perpendicular to both the first direction and the second direction and parallel to the axis of the detected rotating body And a second pair of Hall elements juxtaposed.

  Since the plate-like magnetic body is arranged so as to be perpendicular to the first direction so that it is difficult to reach a magnetic saturation state, conversely, the plate-like magnetic body of the magnetic field detection unit is placed in the N-pole region and the S-pole region Can be placed close to the rotating outer peripheral surface. Therefore, even when non-rare earth magnets having a relatively low magnetic force are used as the constituent members in the N-pole region and the S-pole region, the angle of the detected rotating body can be detected.

When a magnetic flux in the first direction is formed by the N-pole region and the S-pole region, the same magnetic flux in the first pair acts on the two Hall elements, so that the magnetic field is obtained by adding the voltages output from these Hall elements. It is possible to detect the size of components and temporal changes.
On the other hand, when a disturbance magnetic field is applied in the third direction, magnetic fluxes along the first direction but opposite to each other act on the first pair of two Hall elements. The addition of the output voltage cancels the effect of the disturbance magnetic field.

JP 2007-115828 (paragraph numbers 0013 and 0028, FIG. 1 and FIG. 3)

  However, the rotation angle detection device described in Patent Document 1 has a problem that it is difficult to cancel the influence of a disturbance magnetic field that acts from an arbitrary direction other than the third direction. In order to reduce the influence of the disturbance magnetic field, there is known a solution that provides a shield that surrounds the magnetic detection element. However, this solution generally tends to cause a secondary problem that the apparatus becomes large. .

Accordingly, an object of the present invention is to provide a small rotation angle detection device capable of reducing the influence of a disturbance magnetic field acting from an arbitrary direction in order to reduce the influence of the disturbance magnetic field.
Another object of the present invention is to provide a rotation angle detecting device having a simple configuration and higher detection accuracy.

In order to solve the above problems, the first characteristic configuration of the present invention is:
A detected rotating body in which the N pole region and the S pole region are alternately provided around the rotation axis;
A plate-like magnetic body fixed at a position facing the rotation surface formed by the N-pole region and the S-pole region;
And a magnetic detection element disposed between the detected rotating body and the magnetic body.

  In the rotation angle detection device according to the first characteristic configuration of the present invention, the maximum magnetic flux substantially along the first direction generated by the N-pole region or the S-pole region is concentrated so as to be attracted to the magnetic body. A local increase in magnetic flux density occurs around the region where the magnetic material is located. And since the magnetic detection element is arranged near the center of the magnetic flux part having a high density, the angle detection accuracy can be improved, or a magnet having a lower magnetic force is used as a constituent member of the N-pole region and the S-pole region. However, the angle of the detected rotating body can be detected.

  In addition, in the rotation angle detection device according to the first characteristic configuration of the present invention, when there is a disturbance magnetic field in any direction except the magnetic flux along the first direction, the magnetic flux generated by these disturbance magnetic fields is applied to the plate-like magnetic body. There is a tendency to be rectified in an attracted manner. As a result, the magnetic flux generated by the disturbance magnetic field is separated from the magnetic detection element, so that the influence of the disturbance magnetic field does not easily affect the detection result of the magnetic detection element.

  Another characteristic configuration of the present invention is that the N-pole region and the S-pole region are arranged so as to face the radially outer side of the detected rotating body.

  With this configuration, the rotation angle detection device having the simplest and most general configuration that can be downsized and reduced in cost, in which the N-pole region and the S-pole region are arranged so as to face the radially outer side of the detected rotating body. Is obtained. Incidentally, in contrast to the present configuration, the first characteristic configuration of the present invention is arranged such that the N-pole region and the S-pole region are oriented parallel to the axis of the detected rotating body, and magnetic The present invention can also be implemented in a configuration in which the detection element and the magnetic body are juxtaposed in parallel with the axis of the detected rotating body.

  Another characteristic configuration of the present invention is that the magnetic body has a curved shape extending along an outer peripheral surface of the detected rotating body.

  With this configuration, the effect of concentrating the magnetic flux formed by the N-pole region and the S-pole region and the effect of rectifying the magnetic flux due to the disturbance magnetic field become more prominent.

The best mode for carrying out the present invention will be described below with reference to the drawings.
1 and 2 includes a resin case member 1, and a pair of bosses 1a and 1b formed on the upper and lower surfaces of the case member 1 have a rotation shaft 3 as a detection target. It is supported.
Inside the case member 1, a detected rotating body 4 fixed to a part of the rotating shaft 3 is accommodated.

The detected rotating body 4 is composed of a large number of permanent magnets juxtaposed along the circumferential direction, and the N-pole region and the S-pole region having the same circumferential length are the rotational axis R of the rotating shaft 3. Are alternately adjacent to each other.
In addition, a plate-like magnetic body 6 fixed in a position facing the rotation surface formed by the above-described N-pole region and S-pole region is housed inside the case member 1 to form a magnetic detection element. Hall IC 8 to be detected is disposed between the outer peripheral surface of detected rotating body 4 and magnetic body 6.

The length of the magnetic body 6 in the direction along the rotation axis R, that is, the dimension extending parallel to the tangent drawn on the outer peripheral surface of the detected rotating body 4 facing the Hall IC 8 (parallel to the Y axis in FIG. 1). , The width of the magnetic body 6, that is, the dimension extending parallel to the rotation axis R (parallel to the Z axis in FIG. 1), the thickness of the magnetic body 6, and the distance from the outer peripheral surface of the detected rotating body 4 to the Hall IC 8. The ratio between the distance and the distance from the magnetic body 6 to the Hall IC 8 is such that at least a part of a large number of magnetic fluxes originating radially outward from the N pole region and returning to the adjacent S pole region is the magnetic body 6. It is only necessary to set so as to be displaced toward the Hall IC 8 along the circumferential direction by the action of.
The magnetic body 6 has a flat plate shape, and is arranged so that its planar main surface faces the outer peripheral surface of the detected rotating body 4.

  The Hall IC 8 is connected to the connector portion 2 of the case member 1 through power supply wiring and signal wiring (not shown), and is energized through the connector 2 and the magnetic flux density passing through the Hall IC 8 and its A signal having a potential corresponding to the direction of the magnetic flux is output. Therefore, when the rotating shaft 3 rotates, the relative position between the N pole region or the S pole region of the detected rotating body 4 and the Hall IC 8 changes, and the magnetic flux density passing through the Hall IC 8 changes, thereby changing the output of the Hall IC 8. Changes. Based on this output change, the rotation angle (and rotation direction) of the rotating shaft 3 can be detected.

FIG. 3 is an explanatory view showing the magnetic flux distribution formed by the N pole and the S pole constituting the detected rotating body 4 in the rotation angle detecting device according to the present invention based on the estimation, and FIG. It is explanatory drawing which represented based on estimation the magnetic flux distribution in the structure in which the magnetic body 6 of this is not provided.
In FIG. 3, as a result of the magnetic flux extending from the N pole toward the S pole being attracted to the magnetic body 6, the maximum first passing through the vicinity of the Hall IC 8 compared to the configuration of FIG. 4 without the magnetic body 6. A state in which the magnetic flux oriented in the direction (X axis perpendicular to the rotation axis R) is increased in density is shown. As a result, the angle detection accuracy by the Hall IC 8 is improved.

  Further, when there is a disturbance magnetic field in an arbitrary direction except for the magnetic flux along the first direction in the vicinity of the rotation angle detection device, the magnetic flux generated by these disturbance magnetic fields is rectified in a form that is attracted to the plate-like magnetic body 6. Tend to occur. As a result, since the magnetic flux generated by the disturbance magnetic field is separated from the Hall IC 8, the influence of the disturbance magnetic field is hardly exerted on the angle detection result by the Hall IC 8.

[Another embodiment]
As illustrated in FIG. 4, it is possible to use a magnetic body 16 having a curved shape extending along the outer peripheral surface of the detected rotating body 4. In this configuration, it is possible to further expand the direction of the magnetic flux by the applicable disturbance magnetic field.

The top view of the angle detector by this invention 1 is a cross-sectional side view of the angle detection device of FIG. Schematic showing the magnetic flux distribution of the angle detector according to the invention Schematic showing magnetic flux distribution according to another embodiment of the present invention. Schematic showing magnetic flux distribution according to the prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case member 3 Rotating shaft 4 Rotating bodies 6 and 16 to be detected Magnetic body 8 Hall IC

Claims (3)

A detected rotating body in which the N pole region and the S pole region are alternately provided around the rotation axis;
A plate-like magnetic body fixed at a position facing the rotation surface formed by the N-pole region and the S-pole region;
A rotation angle detection device comprising: a magnetic detection element disposed between the detected rotating body and the magnetic body.   The rotation angle detection device according to claim 1, wherein the N-pole region and the S-pole region are arranged so as to face a radially outer side of the detected rotating body.   The rotation angle detection device according to claim 1, wherein the magnetic body has a curved shape extending along an outer peripheral surface of the detected rotating body.

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