JP2002340513A - Rotation angle sensor - Google Patents

Abstract

(57) [Problem] To provide a rotation angle sensor capable of measuring a rotation angle of 360 ° with a small number of parts and a simple shape. A rotation angle sensor (1) according to the present invention generates a rotating shaft (2) rotated by rotation of an object to be measured, a parallel magnetic field rotating with the rotation of the rotating shaft (2), and is perpendicular to the parallel magnetic field. A tubular magnet 4 for generating a vertical magnetic field whose direction is switched with the rotation of the rotating shaft 2, and a magnetic field strength of a parallel magnetic field generated by the tubular magnet 4 are detected, and the magnetic field strength represents a rotation angle of the object to be measured. A non-linear Hall IC 5 that converts the output voltage into a first output voltage and outputs the first output voltage;
And a latch operation type Hall IC 6 for detecting the magnetic field strength of the vertical magnetic field generated in step (a) and outputting a second output voltage that changes in accordance with a change in the direction of the vertical magnetic field.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle sensor for magnetically detecting a rotation angle of an object to be measured. The present invention relates to a rotation angle sensor that measures a rotation angle of an object to be measured using a vertical magnetic field whose direction is switched.

[0002]

2. Description of the Related Art As a conventional rotation angle sensor, for example, there is a magnetic position sensor using a Hall element disclosed in Japanese Patent Application Laid-Open No. 8-35809. As shown in FIG.
In the conventional magnetic position sensor, a tubular yoke 112 is integrally arranged on a drive shaft 111, and a permanent magnet 115 is adhered inside a tubular portion 113 of the tubular yoke 112,
Further, the stators 116 and 117 in which the Hall elements 119 are accommodated are disposed inside the inside.

This magnetic position sensor is configured to output a magnetic field intensity proportional to the rotation angle, and the magnetic field intensity is detected by a Hall element to obtain a voltage output proportional to the rotation angle. ing.

[0004]

However, the above-described conventional magnetic position sensor requires a stator and a tubular yoke in addition to the permanent magnet, and has a complicated shape and a large number of parts, so that the cost is high. There was a problem of becoming. Further, there is another problem that the magnetic field intensity in proportion to the rotation angle cannot be output unless the mounting accuracy of each component such as the stator is high.

When the magnetic field in the stators 116 and 117 is not a target, that is, when the magnetic pole boundaries of the permanent magnets 115 are displaced from the center lines of the stators 116 and 117, the magnetic fields in the stators 116 and 117 There is a problem in that a rotational torque is generated because the target is magnetically stable. For this reason, when a conventional magnetic position sensor is attached to a rotating device having a small driving torque, there is a fear that the rotating device stops rotating.

Further, in a conventional magnetic position sensor, a stator 116 made of a magnetic material is
Since the magnet 117 is arranged, a large attractive force is generated between the permanent magnet 115 and the stators 116 and 117 by a magnetic force. Therefore, the permanent magnet 115 and the stators 116 and 11
Unless each of them is fixed firmly, it is sucked by one of them, and there is also a problem that desired characteristics cannot be obtained.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rotation angle sensor which has a small number of parts, can be manufactured in a simple shape, and is inexpensive.

[0008]

In order to achieve the above object, a rotation angle sensor according to the first aspect of the present invention is a rotation angle sensor for measuring a rotation angle of an object to be measured. A rotating shaft that is rotated by the rotation of an object and a parallel magnetic field that rotates with the rotation of the rotating shaft are generated, and a vertical magnetic field that is perpendicular to the parallel magnetic field and that changes direction with the rotation of the rotating shaft is generated. A magnetic field generator, and a parallel magnetic field detector for detecting a magnetic field strength of the parallel magnetic field generated by the magnetic field generator, converting the magnetic field strength into a first output voltage representing a rotation angle of the object to be measured, and outputting the first output voltage. Means, a vertical magnetic field detecting means for detecting a magnetic field intensity of the vertical magnetic field generated by the magnetic field generating means, and outputting a second output voltage which changes in accordance with a change in the direction of the vertical magnetic field; Inspection Said output by means second
And a rotation angle calculating means for correcting the first output voltage based on the output voltage to calculate a rotation angle of the object to be measured.

According to the first aspect of the present invention, the number of parts can be reduced with a simple shape,
A rotation angle of 60 ° can be measured.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of a rotation angle sensor according to the present embodiment will be described with reference to FIG.

As shown in FIG. 1, a rotation angle sensor 1 is mounted on a rotating shaft 2 which rotates by rotation of a measuring object and a magnet fixed base 3 which rotates with the rotating shaft 2, and a tubular magnet which generates a magnetic field. 4, a non-linear Hall IC 5 for detecting a parallel magnetic field generated by the tubular magnet 4 and outputting a voltage, and a latch operation type Hall IC 6 for performing a latch operation by a vertical magnetic field generated by the tubular magnet 4.
And a case 7 containing the tubular magnet 4 and the like, and a substrate 8 on which a non-linear Hall IC 5 and a latch operation type Hall IC 6 are installed.

Here, the substrate 8 has a non-linear Hall IC
Although not shown, a rotation angle calculation means for calculating a rotation angle from the output voltage of the Hall IC 6 and the output voltage of the latch operation type Hall IC 6 is provided.

Further, the tubular magnet 4 and the non-linear Hall IC
FIG. 2 shows the arrangement of the latch IC 5 and the latch operation type Hall IC 6. Here, the non-linear Hall IC 5 may be installed at any position as long as a parallel magnetic field can be detected. However, as shown in FIG. 2, when the non-linear Hall IC 5 is installed at the intersection between the magnet end face of the tubular magnet 4 and the rotation axis, the magnetic field strength of the parallel magnetic field Is most preferable because it is most stable.

The tubular magnet 4 is a permanent magnet whose central portion of the rotating shaft is hollowed out and magnetized so that the N and S poles have a target shape. This is a magnetic field generating means for generating a parallel magnetic field perpendicular to the magnetic field. Therefore, the shape of the tubular magnet 4 may be a column, a rectangular parallelepiped, or another shape as long as the shapes of the N pole and the S pole are targets. Also, the hollowing out of the center of the rotating shaft may be not a columnar shape but a rectangular parallelepiped shape or another shape as long as the shapes of the N pole and the S pole are targeted.

Further, since the tubular magnet 4 is a permanent magnet magnetized so that the N and S poles have a target shape, a vertical magnetic field perpendicular to the parallel magnetic field on the rotation axis is also generated. As the tubular magnet 4 rotates, the direction of the vertical magnetic field switches.

Next, the principle of measuring the rotation angle by the rotation angle sensor of this embodiment will be described.

In the principle diagram shown in FIG. 3, a parallel magnetic field is obtained at the intersection P between the magnet end face of the tubular magnet 4 and the rotation axis as described above. Therefore, when the tubular magnet 4 is rotated by the rotation of the measurement object, the sine waveform as shown by the solid line in FIG.

On the other hand, the tubular magnet 4 also generates a vertical magnetic field in the z direction, and the direction of the magnetic field switches when passing through the boundary between the N pole and the S pole as the tubular magnet 4 rotates. .

Then, the intensity of the parallel magnetic field at the intersection P is detected by the non-linear Hall IC 5 as shown in FIG.
The output voltage as indicated by the dotted line in FIG.
Output from

Here, while the normal Hall IC outputs a voltage proportional to the magnetic field strength, the nonlinear Hall I
C5 is a Hall IC configured so as to obtain a desired output voltage with respect to the magnetic field strength. Here, the output voltage as indicated by the dotted line with respect to the magnetic field strength indicated by the solid line in FIG. Non-linear Hall IC that outputs
Is used.

On the other hand, the latch operation type Hall IC 6
It is a Hall IC that outputs an output voltage as shown in FIG. 5 with respect to the magnetic flux density, and detects the magnetic field of the tubular magnet 4 in the z direction.

As described above, the non-linear Hall IC 5 having the output characteristic shown in FIG. 4 and the latch operation type Hall IC 6 having the output characteristic shown in FIG. And the magnetic field strength with respect to the rotation angle at each installation position is measured, the measurement results as shown in FIG. 7 are obtained.

In FIG. 7, the solid line indicates the non-linear hole I.
The change in the magnetic field strength of the parallel magnetic field at the installation position of C5, and the dotted line is the change in the magnetic field strength in the z direction at the installation position of the latch operation type Hall IC 6.

The non-linear Hall IC 5 and the latch operation type Hall I
The change in the output voltage of C6 is as shown in FIG.

However, according to the characteristics of the output voltage of the non-linear Hall IC shown by the solid line in FIG.
Since two angles appear between degrees, it is impossible to detect a rotation angle from 0 ° to 360 °.

Therefore, when the output voltage of the non-linear Hall IC shown in FIG. 8 is corrected based on the output voltage of the latch operation type Hall IC using a simple circuit as shown in FIG. 9, the output voltage is proportional to the rotation angle. From 0 ° to 360 ° based on the output voltage.
The rotation angle up to can be detected.

Here, the circuit shown in FIG. 9 is provided on the substrate 8.

As described above, since the correction can be performed with a simple circuit as shown in FIG. 9, there is no need to provide an expensive arithmetic circuit such as a microcomputer.

Further, if the tubular magnet 4 can obtain a parallel magnetic field and a perpendicular magnetic field and can rotate around the rotating shaft 2, the rotation angle sensor of the present embodiment can be realized. The structure is not particularly limited.

For example, as shown in FIGS. 10 and 11,
Even in a ring magnet with outer and inner two-pole magnetization, a parallel magnetic field can be obtained at the center of the magnet, and a vertical magnetic field whose direction switches with rotation can also be obtained, so that it can be used as a magnetic field generating means. is there.

However, in this case, it is necessary to install the latch operation type Hall IC at a position as shown in FIG.

As described above, the rotation angle sensor according to the present embodiment is composed of only the magnet and the Hall IC, and does not require components such as the stator and the tubular yoke. Costs can be reduced by reducing the cost.

Further, since no stator is used, no rotational torque is generated, and therefore, it is possible to mount the apparatus on a rotating device having a small driving torque.

Further, by not using the stator, no attractive force is generated between the tubular magnet and the stator, so that it is not necessary to firmly fix the rotating shaft and the tubular magnet, and the rotating shaft has strength. Therefore, it is not necessary to use a strong material such as a metal, and it is possible to use a general resin material such as nylon.

Further, by correcting the output voltage of the non-linear Hall IC 5 based on the output voltage of the latch operation type Hall IC 6, a rotation angle sensor capable of measuring a rotation angle of 0 to 360 ° can be realized. .

Further, since the correction can be performed by a simple circuit as shown in FIG. 9 and an expensive arithmetic circuit such as a microcomputer is not required, the rotation angle of 360 ° can be measured at low cost. A rotation angle sensor can be realized.

[0037]

As described above, according to the rotation angle sensor of the present invention, a rotation angle sensor having a simple shape and a small number of parts can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of a rotation angle sensor according to the present invention.

FIG. 2 is a view for explaining the arrangement of the tubular magnet, the non-linear Hall IC, and the latch operation type Hall IC shown in FIG. 1;

FIG. 3 is a diagram for explaining a magnetic field generated by the tubular magnet shown in FIG.

FIG. 4 is a diagram for explaining output voltage characteristics of the non-linear Hall IC shown in FIG. 1;

FIG. 5 is a diagram for explaining output voltage characteristics of the latch operation type Hall IC shown in FIG. 1;

6 is a diagram for explaining the arrangement of the tubular magnet, the non-linear Hall IC, and the latch operation type Hall IC shown in FIG. 1;

FIG. 7 is a diagram for explaining the magnetic field strength at the installation positions of the non-linear Hall IC and the latch operation type Hall IC.

FIG. 8 is a diagram for explaining output voltage characteristics of the rotation angle sensor according to the present invention.

FIG. 9 is a circuit diagram of a circuit for correcting output characteristics of the non-linear Hall IC.

FIG. 10 is a diagram showing an example of a radially magnetized ring magnet.

FIG. 11 is a diagram illustrating an example of a ring magnet that is magnetized in a lateral direction.

FIG. 12 is a diagram for explaining an arrangement of a tubular magnet, a non-linear Hall IC, and a latch operation type Hall IC.

FIG. 13 is a sectional view showing a configuration of a conventional magnetic position sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotation angle sensor 2 Rotation axis 3 Magnet fixing stand 4 Tubular magnet 5 Non-linear Hall IC 6 Latch operation type Hall IC 7 Case 8 Substrate 111 Drive shaft 112 Tubular yoke 113 Tubular part 115 Permanent magnet 116 Stator 117 Stator 119 Hall element

Claims (1)

[Claims] 1. A rotation angle sensor for measuring a rotation angle of an object to be measured, comprising: a rotation shaft that rotates by rotation of the measurement object; and a parallel magnetic field that rotates with the rotation of the rotation shaft. A magnetic field generating means for generating a vertical magnetic field which is perpendicular to the parallel magnetic field and changes its direction according to the rotation of the rotating shaft; detecting the magnetic field strength of the parallel magnetic field generated by the magnetic field generating means; Is converted into a first output voltage representing the rotation angle of the object to be measured, and is output. A parallel magnetic field detector detects the magnetic field strength of the vertical magnetic field generated by the magnetic field generator, and detects the direction of the vertical magnetic field. Vertical magnetic field detecting means for outputting a second output voltage that changes in accordance with the change in the voltage, and correcting the first output voltage based on the second output voltage output by the vertical magnetic field detecting means. Rotation angle sensor, characterized in that it is constituted by a rotation angle calculation means for calculating a rotation angle of the measurement object.