JPH02116753A - Detector for direction of rotation - Google Patents

Abstract

PURPOSE:To achieve a smaller size and a lower cost with the number of voltage generators sufficiently reduced to one only by making a shape of a tooth of a magnetic body mounted on a shaft of a motor asymmetrical to a direction of rotation to detect the direction of rotation from a polarity of an output maximal of a power generator. CONSTITUTION:A magnetic body 7 is mounted on a rotating shaft 8 of a main motor and a tooth is formed on the outer circumference thereof with a shape thereof asymmetrical to a direction of rotation while a voltage generator 9 is provided on the outer circumference thereof 7. Now when the magnetic body 7 rotates, a magnetic flux to the generator 9 changes due to the asymmetrical shape of the tooth thereof and a voltage corresponding to the change is outputted. A waveform shaping circuit 10 outputs a square wave voltage when an instantaneous value of the voltage exceeds a specified value. As the waveform of the square wave voltage differs in polarity depending on the direction of rotation, direction of rotation detecting circuits 11 and 12 discriminate the direction of rotation of the motor from the polarity, positive or negative.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotation direction detection device for detecting the rotation direction of a rotating body such as an electric motor.

[Conventional technology]

Figure 4 shows, for example, the 16-bit microcomputer applied control system J for VVVF inverters for 418 vehicles (November 1985), Japan Railway Cybernetics Council 3rd [Domestic Symposium on Cybernetics Utilization in Railways Proceedings Jl), 206-210, r418 Vehicle VVVF Inverter. 1 is a block diagram illustrating a conventional rotational direction detection device for a traction motor in the described electric vehicle; FIG.

In the figure, (1) is a magnetic body attached to the rotating shaft of the main motor, and a tooth profile is formed at one location on the outer periphery of the magnetic body.

(2) and (3) are pulse generators as voltage generators that are fixedly installed close to the outer periphery of the magnetic body (1), and are arranged offset from each other by 1 degree in the rotational direction. (
4) and (5) are waveform shaping circuits, which output a rectangular wave of a constant height when the output from the pulse generators (2) and (3) exceeds a predetermined set value. (6) is a phase detection circuit that detects the phase difference between the rectangular wave outputs from both waveform shaping circuits (4) and (5).

Next, the operation will be explained. When the main motor rotates, the magnetic body (1) rotates accordingly, and a voltage is generated in the pulse generator (2) (3) due to the magnetic flux change caused by the movement of the tooth profile formed on the outer periphery of the magnetic body (1). .

Now, assuming that the rotational direction of the main motor is in the direction of arrow A shown in the figure, the time point at which the voltage is generated to the pulse generator (3) is electrically 9 times higher than the time point at which the voltage is generated to the pulse generator (2).
Able to be 0° behind. As a result, the phase detection circuit (6
The rectangular wave output from both waveform shaping circuits (4y and (5)) input to the waveform shaping circuit (5) is also delayed by 90 degrees on the waveform shaping circuit (5) side.If the rotation direction is opposite to arrow A, then the waveform shaping circuit ( 5) side is 90' opposite to the waveform shaping circuit (4) side.
move on. Therefore, by detecting the phase difference between the two human power signals using the phase detection circuit (6), it is possible to determine the rotational direction of the main motor.

[Problem to be solved by the invention]

Since the conventional rotational direction detection device is configured as described above, it requires two sets of pulse generators and waveform shaping circuits, making it larger and more expensive. Generator (2) (
3), and it is sometimes difficult to secure the installation space and install it.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a rotational direction detection device that can reduce the number of necessary parts, is small, inexpensive, and easy to install.

[Means to solve the problem]

The rotational direction detection device according to the present invention has a tooth profile of a magnetic material having an asymmetrical shape with respect to the rotational direction, and detects the rotational direction from the polarity of the maximum output value of the voltage generator.

[Effect]

As the rotating body rotates, the magnetic body rotates, and the magnetic flux to the voltage generator changes over time due to the movement of its tooth profile. The voltage generator outputs a voltage according to the rate of change of this magnetic flux. Since the shape of the tooth profile is asymmetrical with respect to the rotation direction, 1
The polarity of the maximum value of the hypertrophic voltage waveform differs depending on the direction of rotation.

Therefore, the rotation direction can be determined from the polarity of this local maximum value.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIG.

In the block diagram of Fig. 1, (7) is a magnetic body attached to the rotating shaft (8) of the main motor, and as shown in Fig. 2 1 in detail, there are teeth (7a) on its outer periphery. It is formed. The tooth profile (7a) is formed in an asymmetrical shape with respect to the rotation direction. In other words, assuming an arbitrary radius passing through the center of rotation, the shape of the tooth profile (7a) is formed so as not to be symmetrical with respect to that radius.

In FIG. 1, (9) is a pulse generator as a voltage generator fixedly installed near the outer periphery of the magnetic body (7), and is equivalent to that used conventionally.

0* is a waveform shaping circuit, which is the same as the conventionally used waveform shaping circuit (4) or (5). αη (b) is a rotational direction detection circuit that operates by determining the polarity of the output pulse from the waveform shaping circuit α0. For example, if the polarity is positive, the rotational direction detection circuit (11) outputs a signal. , when the polarity is negative, the rotation direction detection circuit outputs a signal.

Next, the operation will be explained with reference to FIG. Upper row of Figure 3 (2)
shows each waveform when the magnetic body (7) is rotating in the direction of arrow A, and the bottom row @ shows each waveform when the magnetic body (7) rotates in the direction of arrow B, which is opposite to arrow A. Shows the waveform. In addition, the rotation direction of the magnetic body 7) is shown in (a), and the pulse generator (9) is
The waveform of the magnetic flux φ generated in the part shown in (C) is the waveform of the voltage ■ output from the pulse generator (9),
d) shows the waveform of the voltage ■ output from the waveform shaping circuit 00, respectively. Note that T indicates the time axis. First, a magnetic material (
7) is rotating in the direction of arrow A. In this case, when viewed from the pulse generator (9), the tooth profile (7
The outer peripheral edge of a) approaches rapidly, then gradually moves away, and then approaches rapidly again, repeating the pattern. Therefore, if it is assumed that the voltage is generated in this portion (k is a constant), a waveform as shown in FIG. 2C is obtained as the voltage.

When the absolute value of the instantaneous value of this voltage (■) is greater than or equal to a predetermined set value, the waveform shaping circuit O0 generates a waveform of a constant value according to its polarity.
That is, a rectangular wave voltage V is output. This output waveform is shown in Figure 3 (
Shown in d).

As a result of the above, when the magnetic body (7) is rotating in the direction of arrow A, the waveform shaping circuit αQ outputs a positive pulse voltage V as shown in the upper part of FIG. , the rotational direction detection circuit Ql) outputs a signal in response to this, and it is possible to detect that the rotational direction of the main motor is in the direction of arrow A. On the other hand, when the rotation direction of the magnetic body (7) is in the direction of arrow B, the change in magnetic flux - has a tendency opposite to that in case A, and as a result, the waveform shaping circuit Q□ is shown in Fig. 3 ( d) A negative polarity pulse V as shown in the lower row is output, and the rotation direction detection circuit @ outputs a signal in response. Therefore, it can be detected that the rotation direction of the main motor is in the direction of arrow B.

As described above, the rotational direction of the main motor can be determined by one set of the pulse generator (9) and the waveform shaping circuit α0, which makes the main motor compact, easy to install, and inexpensive.

In the above embodiment, the pulse generator (9) was used as the voltage generator, but any type of generator that induces a voltage by electromagnetic induction based on the change in magnetic flux caused by the movement of the tooth profile (7a) of the magnetic body (7) may also be used. For example, the same effect can be achieved even with other types. Further, although the waveform shaping circuit a1 and the rotational direction detection device (b) are used, any type of device may be used as long as it can determine the polarity of the maximum value of the output of the voltage generator. Furthermore, although the shape of the tooth profile (7a) is set to have a period of 90', this period may be expanded or contracted as appropriate depending on the rotational speed of the main motor, the characteristics of the subsequent detection circuit, etc.

Furthermore, although the above embodiment describes the case of detecting the rotational direction of the main motor in an electric vehicle, the present invention is not limited to this, and can be widely applied to detecting the rotational direction of a rotating body.

〔Effect of the invention〕

As described above, in this invention, the tooth profile of the magnetic material is shaped asymmetrically with respect to the rotation direction, and the rotation direction is detected from the polarity of the maximum output value of the voltage generator, so that only one voltage generator can be used. It is small, inexpensive, and easy to install.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a rotational direction detecting device according to an embodiment of the present invention, FIG. 2 is a plan view showing the magnetic body shown in FIG. 1 and its tooth profile, and FIG. 3 is a detailed explanation of the invention. FIG. 4 is a block diagram showing a conventional rotational direction detection device. In the figure, (7) is a magnetic material, (7a) is a tooth profile, and (8)
is a rotation axis, (9) is a pulse generator as a voltage generator, 00 is a waveform shaping circuit, and (11) 0■ is a rotation direction detection circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Patent Attorney Masuo Oiwa 0: Rotation axis 9, no V no L again, rotor lO ゛mi, IT shape shaping circuit 11.12: Danfutsu no pottery raft this path no/2 Fig. 2

Claims (1)

[Scope of Claims] A magnetic body attached to the rotating shaft of a rotating body and having an outer periphery formed into a predetermined tooth shape, and a magnetic flux that is fixedly installed near the magnetic body and is generated by movement of the tooth shape based on the rotation of the magnetic body. a voltage generator that generates a voltage due to a change in voltage, and detects the rotational direction of the rotating body from the output of the voltage generator, wherein the tooth profile is asymmetrical with respect to the rotational direction; A rotational direction detection device characterized in that the rotational direction is detected from the polarity of the maximum output value.