JPH03276014A - Magnetic rotational angle detector - Google Patents

Abstract

PURPOSE:To detect the angle of rotation of a rotary machine continuously over the entire area by arranging a magnetoelectric transducing element in a stationary magnetic field produced by an opposite permanent magnet. CONSTITUTION:The magnetic rotational angle detector 1 has its principal part composed of the permanent magnet 3, magnetic pole yokes 5a and 5b, and a magnetic detection unit 7 arranged between them. The plate surfaces 5aa and 5bb of the magnetic pole yokes 5a and 5b face each other in parallel, so the stationary magnetic field MF which crosses them at right angles is produced between the magnetic pole yokes 5a and 5b and rotates as a rotary shaft S rotates. The magnetic detection unit 7 consists of two Hall elements and generqtes an output corresponding to the angle theta of interlinkage between a magnetism sensing surface and the magnetic field MF. The angle theta of interlinkage rotates from 0 to 2pi as the rotary shaft S rotates, so the angle of rotation can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic rotation angle detector that detects the rotation angle of a rotating machine using a magnetoelectric conversion element.

[Prior art 1] Conventionally, as one of the magnetic rotation angle detectors for detecting the rotation angle of a rotating machine, changes in magnetic flux accompanying the rotation of a magnetic drum whose N pole and S pole are alternately magnetized are used to detect the rotation angle of a rotating machine. Magnetoelectric conversion element (
For example, a magnetic encoder is known that detects a rotation angle (analog amount) as a number of pulses (digital amount) by detecting the rotation angle (analog amount) using a Hall element, magnetoresistive element, etc. and outputting it as an electrical pulse signal.

In addition, changes in magnetic flux caused by the rotation of a semicircular permanent magnet directly connected to the rotating shaft are detected by a magnetic resistance element (also called an MR element) formed in a circular pattern, and a voltage signal is output according to the rotation angle. Contactless potentiometers are also known.

[Problems to be Solved by the Invention] However, since the above magnetic encoder has a mechanical structure whose detection accuracy (resolution) is determined by the number of magnetic poles formed on the magnetic drum, it is necessary to use magnetic The drum must be made larger and the number of magnetic poles must be increased, so increasing the detection accuracy poses a problem in that the magnetic drum becomes heavier and the load on the rotating machine increases.

On the other hand, although non-contact potentiometers can continuously detect the rotation angle as a voltage level, there is a detection angle range where the relationship between rotation angle and voltage is not linear, and it is not possible to detect the entire rotation angle. I have a problem.

The present invention has been made with the object of providing a magnetic rotation angle detector that can continuously detect rotation angles over the entire range.

[Means for Solving the Problems 1] The gist of the present invention is a magnetic rotation angle detector for detecting the rotation angle of a rotating machine using a magneto-electric conversion element, comprising: a permanent magnet; magnetic pole members connected to each magnetic pole and disposed facing each other at a predetermined interval, a magnetoelectric conversion element being disposed in the magnetic field space formed between the two magnetic pole members, and the permanent A magnetic rotation angle detector characterized in that either a magnet, a magnetic pole member, or the magnetoelectric transducer is mounted on the rotating shaft of a rotating machine with the same axis.

[Function] In the magnetic rotation angle detector of the present invention configured as described above, magnetic pole members are arranged on each of the magnetic poles of the single permanent magnet so as to face each other at a predetermined interval. Therefore, a steady magnetic field with a constant magnetic flux density is formed between the two magnetic pole members.

When either the permanent magnet, the magnetic pole member, or the magnetoelectric transducer rotates with the rotation of the rotating machine, the direction of the steady magnetic field with respect to the magnetoelectric transducer (the interlinkage angle of the magnetic flux with respect to the magnetoelectric transducer) also changes periodically. Then, the magnetoelectric conversion element detects the periodic change in the direction of the steady magnetic field, converts it into an electric signal, and outputs it.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a magnetic rotation angle detector according to an embodiment, and FIGS. 2(A) and 2(B) are illustrations of the arrangement of a magnetic detection unit.

As shown in the figure, the magnetic rotation angle detector 1 includes a permanent magnet 3 and a pair of magnetic pole yokes that are shaped like an elongated flat plate and are arranged so that their longitudinal directions are parallel to each other with the permanent magnet 3 in between. 5a, 5b, and a magnetic detection unit 7 arranged in the space between the magnetic pole yokes 5a and 5b as main parts, and the bearing of the motor rotation shaft (hereinafter simply referred to as the rotation shaft) S is inside the part SB. It is stored.

Next, among the pair of magnetic pole yokes 5a and 5b, the plate surface 5aa of one magnetic pole yoke 5a is connected to the N-pole side end surface of the permanent magnet 3, and the plate surface 5bb of the other magnetic pole yoke 5b is connected to the S-pole side end surface of the permanent magnet 3. , are connected to each other. In addition, each magnetic pole yoke 5a, 5
One end of b (for friend mounting, attach the shaft end S of the rotating shaft S via the member 9
The permanent magnet 3 and the magnetic pole yokes 5a and 5b are configured to rotate integrally with the rotating shaft S with the same axis. Therefore, the plate surfaces 5aa, 5bb of the magnetic pole yokes 5a, 5b are opposed to and parallel to each other, so a magnetic field MF orthogonal to the plate surfaces 5a, 5b is formed between the magnetic pole yokes 5a, 5b, and the rotation axis As S rotates, the magnetic field MF also rotates. The magnetic flux density of this magnetic field M is kept constant because the bearing of the magnetic rotation angle detector 1 is magnetically shielded from the outside by the iron case C of part SB.
The magnetic field MF is a steady magnetic field.

The magnetic detection unit 7 consists of two Hall elements 11a and 11b, which are magnetoelectric conversion elements.
b is each magnetic field detection surface (hereinafter referred to as magnetically sensitive surface) llaa
, 11bb are fixed on the support substrate 13 so as to be orthogonal to each other and form an L-shape. Support substrate in the form of a long and narrow plate 1. i+i The bearing is placed in the part S so that the orthogonal point of the Hall elements 11a and llb is located on the extension line of the axis of the rotating shaft S.
It is fixed to the side wall SBa of B. In addition, the support substrate 13
There are signal lines SLa and S of the Hall elements 11a and llb.

Hall elements 11a, 11bE As is well known, since they output a voltage (Hall voltage) according to the strength of the applied magnetic field, the strength of the magnetic field M (=magnetic flux density) B and the control current IC If constant, magnetically sensitive surfaces 11aa, 11bb
Outputs a voltage vH according to the interlinkage angle θ of the magnetic field MF with respect to the magnetic field MF (VH= k
is the Hall element] product sensitivity of 1a and llb). Note that as the Hall elements 11a and 11b, there are known examples such as gallium arsenide hall sensors and indium antimony hall sensors (THSI○2A manufactured by Toshiba Corporation,
5H8IIO manufactured by Mitsubishi Electric, etc.).

When the magnetic field M'' rotates with the rotation (clockwise) of the rotation axis S, that is, when the interlinkage angle θ changes periodically in the range of O to 2π, the Hall elements 11a and 11b generate the detection signal V.
Output Ha, V Hb. The detection signals VHa and VHb are expressed by the following equations.

VHa=KXcos ωt VHb= KXcos(π/2−ωt)=KXsin
ωt<e=ωt, = kXlcXB) These detection signals VHa, VHbf and signal line SLa
, SLb to the signal processing circuit 30.

As shown in FIG. 3, the signal processing circuit 30 includes a Hall element 1
Differential amplifiers 32a and 32b take out and amplify the voltage (=output voltage VHa, VHb) between output terminals T] and T2 of output terminals 1a and 11b, and input signals (sinω and COSωt) from these differential amplifier circuits 32. ) and a conversion module 34 that creates a rotation angle signal Vθ (= arcsinωt) based on the rotation angle signal Vθ (=arcsinωt).
It is housed in a control panel (shown in the diagram) located outside.

The conversion module 34 (detects the rotation angle θ (=ωt) from two input signals (sinω and cosωt), and integrates a subtracter, an arc sine function generator, etc. It is well known, for example, model 4302 manufactured by Burr-Brown.

Further, a drive circuit 50 consisting of a constant current circuit is also provided in the control panel, and supplies a control current IC to the Hall elements 11a and 1b via power supply lines PLLa and PLb.

In the magnetic rotation angle detector 1 configured as described above, when the magnetic field M rotates with the rotation of the rotation axis S, the magnetic detection unit 7 is activated as shown in FIGS. 4(A) and 4(B). The detection signals VHa, VHb are output to the signal processing circuit 30, and the signal processing circuit 30 outputs the detection signals VHa, VHb.
A rotation angle signal Vθ is output based on Hb.

As described above, the magnetic rotation angle detector 1 of this embodiment is
A magnetic field MF is formed between a pair of magnetic pole yokes 5a and 5b arranged so that their longitudinal directions are parallel to each other with a permanent magnet 3 in between, and a magnetic detection unit 7 is arranged within the magnetic field MF. Since the direction of the magnetic field M that rotates with the rotation axis S is detected, the rotation angle θ can be detected continuously.Therefore, there is no area where the rotation angle cannot be detected accurately as in the conventional case, and the entire area can be detected. The rotation angle θ can be accurately detected over the range (0 to 2π).

In addition, it has an extremely simple structure in which the flat magnetic pole yokes 5a, 5b are joined to the permanent magnet 3, and the magnetic pole yokes 5a, 5b are connected to the permanent magnet 3.
Since it is formed thinly, it can be made lightweight. Therefore, there is no need to increase the load on the rotating shaft S by increasing the size of the magnetic drum in order to improve detection accuracy, as is the case in the past.

Here, in this embodiment, the permanent magnet 3 and the magnetic pole yoke 5a,
5b is configured to rotate, but the magnetic detection unit 7
Alternatively, it may be configured such that the axis of rotation S and the axis thereof are the same so that they rotate together. In this case, as shown in FIG. 5, it is also possible to arrange the magnetic pole yokes 5a, 5b so that the longitudinal direction thereof is orthogonal to the axial direction of the rotating shaft S.

Furthermore, in an environment with rapid temperature changes, fluctuations in the strength of the magnetic field MF due to temperature changes poses a problem, but in such cases, as shown in the figure, the gap between the magnetic pole yokes 5a and 5b is The magnetic flux density of the magnetic field MF is kept constant by being bridged by the magnetic shunt alloy 60 whose magnetic permeability changes accordingly to buffer fluctuations in the strength of the magnetic field MF due to temperature changes. In this way, temperature compensation of the magnetic rotation angle detector 1 can be performed.

In addition, as a magnetic shunt alloy (for example, 5JK manufactured by Toshiba Corporation)
-A, 5JK-B, 5JK-C, etc. are used.

Furthermore, in this embodiment, the Hall elements are arranged in an L-shape, but in addition to this, as shown in FIGS. 6(A) and (B),
They may be arranged in a T-shape.

[Effects of the Invention] As explained above, according to the present invention, a steady magnetic field is formed between a pair of magnetic pole members arranged to face each other with a permanent magnet in between, and The magneto-electric transducer detects changes in the direction of the magnetic field that rotates with the rotation of the rotating machine, so the rotation angle of the rotating machine can be continuously detected over the entire range.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of the magnetic rotation angle detector of the embodiment, Fig. 2
Figures (A) and (B) are explanatory diagrams showing the arrangement of the magnetic detection unit, and Figure 3 is a block diagram showing the signal processing circuit.
4(A) is a graph representing the detection signal waveform of the Hall element, FIG. 4(B) is a graph representing the output signal waveform of the conversion module, FIG. 5 is an explanatory diagram of another embodiment, and FIG. 6( A) and (B) are explanatory diagrams showing different arrangements of magnetic detection units. 1...Magnetic rotation angle detector 3...Permanent magnet 5
a, 5b...Magnetic pole yoke 7...Magnetic detection unit

Claims (1)

[Claims] A magnetic rotation angle detector that detects the rotation angle of a rotating machine using a magneto-electric conversion element, comprising: a permanent magnet; magnetic pole members arranged to face each other, a magnetoelectric conversion element is arranged in a magnetic field space formed between the two magnetic pole members, and any one of the permanent magnet and the magnetic pole member and the magnetoelectric conversion element is provided. A magnetic rotation angle detector characterized in that one of the two is mounted on the rotating shaft of a rotating machine with the same axis.