JPH09196610A - Rotation angle detector - Google Patents

Abstract

(57) Abstract: It is possible to detect a continuous rotation angle and an absolute rotation position, improve reliability, and reduce cost. SOLUTION: The coils 11 and 12 are driven by a DC power supply 14.
When the windings 11a and 12a of the coil are energized, the coils 11 and 12 are
A DC magnetic field is generated between them. When the measurement target rotates, the variable inductance elements 21 and 22 of the magnetic orientation sensor 13 rotate, the angle formed by the variable inductance elements 21 and 22 with the direction of the DC magnetic field changes, and the inductance of the variable inductance elements 21 and 22 changes. Change. Therefore, the angle formed by the variable inductance elements 21 and 22 with the direction of the DC magnetic field, that is, the rotation angle of the measurement target can be obtained based on the parameter that changes according to the change in the inductance of the variable inductance elements 21 and 22. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle detecting device using a magnetic bearing sensor.

[0002]

2. Description of the Related Art Conventionally, magnetic resolvers and rotary encoders have been known as rotation angle detecting devices utilizing magnetism. FIG. 4 is a perspective view showing a schematic configuration of such a conventional rotation angle detecting device. This rotation angle detection device includes a rotation shaft 101 connected to a rotation shaft to be measured,
Disc-shaped rotating body 10 attached to the rotating shaft 101
2, a plastic magnet 103 attached to the outer peripheral portion of the rotating body 102, and a magnetic sensor 104 such as a magnetoresistive element arranged at a position facing the plastic magnet 103. N poles and S poles are alternately magnetized at a predetermined pitch P on the plastic magnet 103. In this rotation angle detection device, when the rotating body 102 rotates according to the rotation of the measurement target, the N pole and the S pole on the plastic magnet 103 alternately face the magnetic sensor 104, and the output of the magnetic sensor 104 changes. . Therefore, from the output of the magnetic sensor 104, the number of N-poles or S-poles that have passed in front of the magnetic sensor 104 is obtained. If this number is n and the outer circumference of the plastic magnet 103 is L, the rotation angle θ ( °) is θ = (nP /
L) × 360.

[0003]

However, the rotation angle detecting device shown in FIG. 4 has a problem that the rotation angle cannot be continuously detected because the rotation angle can be obtained only by a digital amount. Further, since only the change amount of the rotation angle, that is, the relative value of the rotation angle is obtained, the absolute value of the rotation angle, that is, the absolute rotation position cannot be detected. In addition, dust may enter the gap between the plastic magnet 103 and the magnetic sensor 104, and the plastic magnet 103 and the magnetic sensor 104 may be damaged and malfunction, resulting in poor reliability. Further, since the plastic magnet 103 is required and the processing for alternately magnetizing the N pole and the S pole on the plastic magnet 103 is required, there is a problem that the cost is increased.

The present invention has been made in view of the above problems, and its object is to enable continuous rotation angle detection and absolute rotation position detection, as well as high reliability and cost reduction. It is to provide a rotation angle detection device capable of reducing the rotation angle.

[0005]

According to a first aspect of the present invention, there is provided a rotation angle detecting device including a DC magnetic field generating means for generating a DC magnetic field,
A rotating unit connected to the object to be measured and having a central axis of rotation arranged in the DC magnetic field so as to intersect the direction of the DC magnetic field generated by the DC magnetic field generating means,
A magnetic azimuth sensor for detecting the angle formed by the rotating portion with respect to the direction of the DC magnetic field is provided.

According to a second aspect of the rotation angle detecting device of the first aspect, in the rotation angle detecting device of the first aspect, the rotating parts of the magnetic azimuth sensor are arranged so as to be orthogonal to each other. It is configured to have two variable inductance elements including a winding wound around the ferromagnetic portion and having an inductance that changes according to an external magnetic field.

In the rotation angle detecting device according to the first aspect, when the measuring object rotates, the rotating portion of the magnetic direction sensor rotates,
The angle that this rotating part makes with the direction of the DC magnetic field changes. Therefore, the rotation angle of the measurement target can be obtained by detecting the angle formed by the rotating portion and the direction of the DC magnetic field with the magnetic direction sensor.

In the rotation angle detecting device according to the second aspect, when the object to be measured rotates, the two variable inductance elements rotate and the inductance of each variable inductance element changes. Therefore, the rotation angle of the measurement target can be obtained by measuring the parameter that changes according to the change in the inductance of each variable inductance element.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory view showing the configuration of a rotation angle detecting device according to an embodiment of the present invention. The rotation angle detection device according to the present embodiment includes two coils 11 and 12 as a DC magnetic field generating unit that generates a DC magnetic field, and a magnetic direction sensor 13 arranged between the coils 11 and 12. There is. The coils 11 and 12 are, for example, cylindrical magnetic cores 11a and 12a and the magnetic core 11
and windings 11b and 12b wound around a and 12a. The magnetic cores 11a and 12a are arranged in a straight line with a predetermined gap therebetween, and the windings 11b and 12b are wound in the same direction. The windings 11b and 12b have
DC voltage in the same direction is applied by the DC power supply 14,
As a result, a substantially uniform and parallel DC magnetic field is formed between the coils 11 and 12.

The magnetic direction sensor 13 includes coils 11 and 12
A frame body 16 disposed between the frame body 16 and a central portion of the frame body 16 is arranged so as to be orthogonal to the direction of the DC magnetic field generated by the coils 11 and 12, and is rotatably supported by the frame body 16. The rotary shaft 17 and the two variable inductance elements 21, 2 attached to the rotary shaft 17.
2 is provided. The rotating shaft 17 and the variable inductance elements 21 and 22 form a rotating body. Rotating shaft 17
Is connected to the rotating shaft of the measurement target and is rotated with the rotation of the measurement target. The two variable inductance elements 21 and 22 are arranged so as to be orthogonal to each other.

The variable inductance elements 21 and 22 are elements whose inductance changes according to an external magnetic field,
Each of them is composed of, for example, an elongated plate-shaped base body, a ferromagnetic body layer as a ferromagnetic body portion formed on the base body, and a winding wound around the base body and the ferromagnetic body layer. ing. As the material of the ferromagnetic layer, for example, Co70
%, Fe 6%, Si 15%, B 9% amorphous is used. The shape of the ferromagnetic layer is, for example, 20 m long
m, width 0.2 mm, thickness 20 to 50 μm. The ferromagnetic layer is formed by, for example, a method in which a ferromagnetic material processed into a predetermined shape is adhered to a substrate with an epoxy resin or the like, or a ferromagnetic material is sputtered on the substrate. The winding is formed by winding a conductive wire 200 times, for example.

FIG. 2 is a circuit diagram showing an example of the configuration of a circuit for detecting a rotation angle by using the rotation angle detection device according to this embodiment. In this circuit, a resistor 32 is attached to the windings 21a and 22a of the variable inductance elements 21 and 22, respectively.
A high-frequency power source 31 that applies a high-frequency voltage via the detectors, detection circuits 33 and 34 that detect the amplitude of the voltage across the windings 21a and 22a, and the rotation angle is calculated based on the outputs of the detection circuits 33 and 34. And an arithmetic circuit 35 that operates.
The high frequency power supply 30 is adapted to apply a sinusoidal voltage of 1 MHz to the windings 21a and 22a.

Next, the operation of the rotation angle detecting device according to this embodiment will be described. When the DC power supply 14 energizes the windings 11 a and 12 a of the coils 11 and 12, a DC magnetic field is generated between the coils 11 and 12. When the measurement target rotates, the variable inductance elements 21 and 22 of the magnetic orientation sensor 13 rotate and each variable inductance element 21 and
The angle that 22 makes with the direction of the DC magnetic field changes, resulting in
When viewed from the variable inductance elements 21 and 22, the external magnetic field changes, and the variable inductance elements 2
The inductances of 1 and 22 change. Therefore, based on the parameter that changes according to the change in the inductance of each variable inductance element 21, 22, the angle formed by each variable inductance element 21, 22 with the direction of the DC magnetic field,
That is, the rotation angle of the measurement target can be obtained.

In the circuit shown in FIG. 2, the detection circuit 33 detects the amplitude of the voltage across the winding 21a of the variable inductance element 21, and the detection circuit 34 detects the voltage across the winding 22a of the variable inductance element 22. The amplitude is detected. The amplitudes detected by the detection circuits 33 and 34 change according to the angle formed by the variable inductance elements 21 and 22 with the direction of the DC magnetic field, that is, the rotation angle of the measurement target. In FIG. 3, the angle formed by the variable inductance element 22 with respect to the direction of the DC magnetic field is the rotation angle θ ° as shown in FIG. 1, and the detection circuit 3 when the rotation angle is 0 °.
3 shows the relationship between the rotation angle θ and the amplitudes detected by the detection circuits 33 and 34, where the amplitude detected by 3 is 0. Reference numeral 41 indicates the amplitude detected by the detection circuit 33, and reference numeral 42 indicates The amplitude detected by the detection circuit 34 is shown. As can be seen from this figure, the amplitudes detected by the detection circuits 33 and 34 are sinusoidal waveforms whose phases are shifted by 90 °.

When the amplitude detected by the detection circuit 33 is X and the amplitude detected by the detection circuit 34 is Y, X and Y are expressed by the following equations. However, A is the maximum value of each amplitude X and Y.

[0017]

## EQU1 ## X = Asin θ Y = A cos θ

From the above equation, the rotation angle θ can be obtained by the following equation.

[0019]

[Equation 2] θ = tan ⁻¹ (Y / X)

The arithmetic circuit 35 shown in FIG.
Each amplitude X, Y detected by each detection circuit 33, 34
The rotation angle θ is calculated based on

As described above, the rotation angle detecting device according to the present embodiment enables continuous rotation angle detection and absolute rotation position detection. Further, since the gap between the magnetic direction sensor 13 and the coils 11 and 12 may be large, it is possible that dust may enter the gap and cause a failure like the conventional rotation angle detecting device as shown in FIG. And reliability is improved. Further, the cost can be reduced because the plastic magnet is unnecessary and the process of alternately magnetizing the N pole and the S pole on the plastic magnet is unnecessary.

The present invention is not limited to the above embodiment, and for example, a permanent magnet may be used as the DC magnetic field generating means.

[0023]

As described above, according to the rotation angle detecting device of the present invention, a DC magnetic field is generated, and the angle formed by the rotating portion of the magnetic direction sensor and the direction of the DC magnetic field is detected to measure the object to be measured. Since the rotation angle is obtained, continuous rotation angle and absolute rotation position can be detected. Moreover, dust is not generated in the gap and it is highly reliable. Since it is unnecessary and the processing of alternately magnetizing the N pole and the S pole on the plastic magnet is unnecessary, it is possible to reduce the cost.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a rotation angle detection device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of a configuration of a circuit for detecting a rotation angle using the rotation angle detection device shown in FIG.

3 is a characteristic diagram showing a relationship between a rotation angle and an amplitude detected by each detection circuit in FIG.

FIG. 4 is a perspective view showing a schematic configuration of a conventional rotation angle detection device.

[Explanation of symbols]

11, 12 ... Coil, 13 ... Magnetic direction sensor, 14 ... DC power supply 21, 22 ... Variable inductance element

Claims (2)

[Claims] 1. A direct-current magnetic field generating means for generating a direct-current magnetic field, the direct-current magnetic field generating means being connected to a measuring object to rotate, and the direct-current magnetic field so that its rotation center axis intersects the direction of the direct-current magnetic field generated by the direct-current magnetic field generating means. A rotation angle detecting device having a rotating portion arranged in a magnetic field, and a magnetic direction sensor for detecting an angle formed by the rotating portion with a direction of the DC magnetic field. 2. The rotating portion of the magnetic bearing sensor is arranged so as to be orthogonal to each other, and includes an elongated ferromagnetic body portion and a winding wound around the ferromagnetic body portion, and an external magnetic field. 2. The rotation angle detecting device according to claim 1, further comprising two variable inductance elements whose inductance changes in accordance with.