JPS59188366A - Frequency generator of servo motor or the like - Google Patents

Abstract

PURPOSE:To obtain an accurate rotating frequency output even under inaccurate state by setting the times of variations in the periodic magnetic fluxes in the portion corresponding to a pole of a drive multipolar magnet to 2n (n=1, 2,...) times. CONSTITUTION:A magnetic unit such as a rotor 2' or the like is secured to a drive multipolar magnet, has a plurality of irregular surfaces formed via radial slots on an annular portion in such a manner that variations in the periodic magnetic fluxes of 2n (n=1, 2,...) occur in the portion corresponding to the pole of the multipolar magnet. A generating strand 3' is disposed to correspond by 1:1 to the variations in the magnetic flux due to the rotor 2' at the position opposed to the rotor 2'. With the boundary between the N-pole and the S-pole of the magnet as a reference the slot of the rotor 2 is displaced at 180 deg. of an electric angle. The variation in the magnetic flux is detected by the generating strand 3' to control the rotating speed of the rotor 2'.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a driving multi-polar magnet, a magnetic material that causes periodic changes in magnetic flux by the multi-polar magnet, and a power generating line element in which a voltage is induced by the magnetic flux change. The present invention relates to a frequency generator such as a servo motor that is configured to detect a frequency output according to a rotational frequency.

Generally, in servo motors, etc., the frequency generator described above detects the rotational frequency of the simoke and converts it into voltage (
It is known that the rotational speed of the motor is controlled using the voltage as a rotational speed limiting voltage.

FIG. 1 shows an example of a frequency generator composed of a driving multi-pole magnet, a magnetic material that causes periodic 8-flux changes by the multi-pole magnet, and a power generating line element.

In this figure, 1 is a driving multipolar magnet in which the N-pole part and the 8-pole part are separately magnetized in the circumferential direction, and 2 is a magnetic body that is fixed to the multipolar magnet 1 and has radial grooves 2A in the annular part. A good rotor 6 is a power generating line element which is arranged in one-to-one correspondence with the magnetic flux change caused by the groove part and detects the magnetic flux change, and the rotor 2 rotates concentrically with this power generating line element 3. As a result, a change in magnetic flux density occurs on the power generation line element 3,
A voltage is induced in this power generating line element 3 and detected as a rotation frequency. The magnetic flux change at this time generally causes 2n+1 (n-1, 2, 3, .) periodic magnetic flux changes in a portion corresponding to one magnetic pole of the multi-pole driving magnet 1. In addition, in the example shown in FIG.
This causes periodic changes in magnetic flux.

Next, the operation shown in FIG. 1 will be explained in detail using FIG. 2. In Figure 2, prison and (@ are power generation line elements 3
and a circumferential sectional view of the rotor 2, (Q is the power generation line element 6
FIG. 3 is a diagram illustrating a simplified state of changes in magnetic flux passing through the magnetic flux, replacing it with a switching operation. In addition, the direction of the induced voltage in (Al) in Figure 2 is (direction from the front to the rear of the drawing) or
It was shown in

Here, the rotor 2 is magnetized in correspondence with the magnetic poles of the single driving multi-pole magnet 1, and is periodically magnetized 2n+1 (n-1, 2, 3...) times in a portion corresponding to one magnetic pole. Grooves are cut with an equal pinch so as to bring about a change in magnetic flux, and the phase in the portions corresponding to adjacent magnetic poles is shifted by 180 degrees in electrical angle with respect to the above-mentioned pitch. Therefore, when the rotor 2 rotates in the direction of the arrow, according to Fleming's right-hand rule, a voltage is induced in the power generating line element 6 in the direction indicated by (Al) in FIG. Output as frequency output.

Actually, it is difficult to make the center of rotation of the groove portion C coincide with the center of rotation of the rotor 2 due to accuracy reasons. Hereinafter, it is assumed that the center of the groove C and the center of rotation of the rotor 2 are slightly deviated from each other. , Now, if we pay attention to the magnetic flux change corresponding to the above boundary, we can see that the magnetic flux change in this part is due to the power generation in other parts within the same pole, as shown by C1 + C2 in (q) in Figure 2. This is very large compared to the magnetic flux change caused by a change in the distance to the wire element 6. Therefore, under the above-mentioned assumption, an error occurs in the mounting position of the driving multi-pole magnet 1. As a result of variations in the magnetization of the driving multi-pole magnet 1, the phase of the boundary between the N and S pole parts of the driving multi-pole magnet 1 and the groove part C is shifted, and the power generation line element 6 This results in a drawback that the rotational frequency output that should originally be output is greatly modulated or distorted.Also, the driving multi-pole magnet 1 is not mounted in a predetermined position with high precision.
Even if there is no variation in the magnetization of the multipolar magnet 1, if the center of the power generating line element 3 and the center of rotation of the rotor are misaligned, the above-mentioned drawbacks will occur. The above-mentioned drawbacks become more serious as the center of the power generating line element 3 and the rotation center of the rotor 2 are closer to each other, and become a particularly large drawback when accuracy cannot be maintained.

The present invention has been made to eliminate the above-mentioned drawbacks.
The number of periodic magnetic flux changes in the part corresponding to the magnetic poles of one multi-pole drive magnet is 2n (n=1.2.3...
) times, it is an object of the present invention to provide a frequency generator that can obtain accurate rotational frequency output even under conditions where accuracy is poor to some extent.

Hereinafter, the operation of an embodiment of the present invention will be explained using the drawings.

In FIG. 3, (A and (131) are circumferential cross-sectional views of the power generating line element 3' and the rotor 2', (Q is a simplified view of changes in the magnetic flux passing through the power generating line element 6', and a switching operation is shown. This is a replaced view. Note that 2'A is a groove provided radially in the annular part of the rotor 2'.As is clear from (Bl) in FIG. It is magnetized in correspondence with the magnetic poles of a multi-pole magnet 1' (not shown), and 2n (n=1.
Grooves are cut at equal pitches so as to cause a periodic change in magnetic flux of 2.3...) times, and in the portions corresponding to adjacent magnetic poles, the phase is shifted by 180 degrees in electrical angle with respect to the above-mentioned pinch. Well, if this rotor 2' is rotating in the direction of the arrow, 1 of the cross section of the power generation line element 3' located at the boundary of the magnetic poles.
If we pay attention to the power generation line element 3'a, which is the
Since h is the moment when the magnetic flux enters the N-pole from the S-pole, the direction of change in the magnetic flux is set upward in the drawing, and the conductor is obtained relative to the rotation direction of the magnetic body (rotor 2) indicated by the arrow. If the moving direction of the power generation line element 3' is to the right in the drawing and Fleming's right-hand rule is applied, the direction of the voltage induced in this power generation line element will be from the front to the rear in the drawing. Focusing on the power generation line element 31), which is a part of the cross section of the power generation line element 6' located at the other boundary of the magnetic poles, the moment when this power generation line element 6'l) enters from the N pole part to the S pole part. Therefore, if Fleming's right-hand rule is similarly applied, the direction of the voltage induced in the power generating line element 3t will be from the rear to the front in the drawing. Here, the direction of the voltage induced in the power generating line element 3h and the voltage induced by the groove portion 28 of the rotor 2' other than the boundary between the magnetic poles is as follows.
Considering the length of the power generation line element 6', the directions are the same, but only the voltage induced in the power generation line element 3'b is in the opposite direction. Therefore, the voltage induced in the power generation line element 3/a and the voltage induced in the power generation line element 6'a cancel each other out.

6t is hardly outputted as the rotational frequency output, and only the voltage induced by the two grooves of the rotor 2' other than the boundaries of the magnetic poles is outputted as the rotational frequency output.

As described above, the present invention includes a driving multi-pole magnet 1' that is magnetized separately in the circumferential direction, and a plurality of concavo-convex portions fixed to the multi-polar magnet 1' and formed by two radial grooves in an annular portion. A magnetic body such as a rotor 2' that has a magnetic flux and causes 2n (n=1.2.3...) periodic magnetic flux changes in a portion corresponding to one magnetic pole of the multipolar magnet 1';
A power generation line element 6' is provided at a position facing the magnetic body so as to correspond one-to-one to the change in magnetic flux due to the magnetic body,
The groove part 28 of the magnetic material is 180' in electrical angle with reference to each boundary between the N pole part and the S pole part of the multipolar magnet 1'.
Since the rotational speed is controlled by detecting the change in the magnetic flux using the power generating line element 6', the center of the groove 2'A and the center of rotation of the rotor 2' are shifted even slightly for accuracy reasons. In this case, the installation of the multi-pole magnet 1' prevents modulation of the rotational frequency output due to positional errors, variations in magnetization of the multi-pole magnet 1', deviation of the center of the generating line element 3', etc. be able to.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing an example of a frequency generator, and Figure 2 (
5) and (Bl is the circumferential cross-sectional view of the power generation line element and rotor in the example shown in Figure 1, and (Q in Figure 2 is the magnetic flux passing through the power generation line element in the example shown in Figure 1). A magnetic flux distribution diagram showing the changes in a simplified manner; (At and old in FIG. 6 are circumferential cross-sectional views of the power generating line element and rotor in an embodiment of the present invention; Q in FIG. 6 is also a diagram of the It is a magnetic flux distribution diagram which simplified the change of the magnetic flux which passes through the power generation line element in one example.1'...Multi-pole magnet-2'...Rotor, 2A...
・Groove, 6'...Power generation wire element. 35 Figure 1 Figure 2 Figure 4 Figure 3 354

Claims (1)

[Claims] A driving multi-polar magnet that is magnetized in sections in the circumferential direction, and a plurality of uneven parts fixed to the multi-polar magnet and formed by radial grooves in an annular part, and one magnetic pole of the multi-polar magnet. 2n (n=1.2.
A magnetic body that causes periodic magnetic flux changes of 3...) times, and a magnetic body that causes 8 flux changes due to the magnetic body at a position facing the magnetic body, and 1
The groove part of the magnetic material is shifted by 180 degrees in electrical angle with respect to each boundary between the N-pole part and the S-pole part of the multipolar magnet. , A frequency generator such as a servo motor, characterized in that the rotational speed is controlled by detecting the magnetic flux change using the power generation line element.