JPH0254021B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a frequency generator that outputs a frequency signal according to the number of rotations of a rotating shaft.

(Prior art) Generally, in a servo motor, etc., a frequency generator is connected to the rotating shaft of the motor, and a frequency signal corresponding to the rotation speed of the motor is detected by the frequency generator.
It is known that this voltage is converted into a voltage (F-V conversion) and this voltage is used as a rotational speed control voltage to control the rotational speed of the motor.

FIG. 1 is an exploded perspective view of an example of a frequency generator. In Fig. 1, numeral 1 is a driving multi-pole magnet in which N-pole portions and S-pole portions are magnetized alternately and equally in the circumferential direction, and numeral 2 is a driving multi-polar magnet fixed to this driving multi-polar magnet 1. It is a rotor made of a magnetic material and has an annular portion disposed around the outer periphery of a multipolar magnet 1. These driving multi-pole magnet 1 and rotor 2 are fixed to a rotating shaft (not shown) and are configured to be freely rotatable. Further, on one side of the annular portion, a plurality of uneven portions are formed at the same pitch by the radial groove portion 2A. The groove portion 2A is shifted in phase by 180 degrees in electrical angle corresponding to the S-pole portion and the N-pole portion of the driving multi-pole magnet 1, and the boundary between the S-pole portion and the N-pole portion is formed by a convex portion. It is formed in a continuous manner. Here, the annular portion of the drive multipolar magnet 1 corresponding to the N pole is magnetized to the S magnetic pole, and a magnetic path is formed between the N pole and the annular portion magnetized to the S magnetic pole. The magnetic flux density is high in the convex part of the annular part and low in the concave part. Similarly, the annular portion of the drive multipolar magnet 1 corresponding to the S pole is N
The magnetic poles are magnetized, and the direction of the magnetic flux is reversed, but the magnetic flux density is high at the convex portion of the annular portion and low at the concave portion.

In this way, due to the unevenness of the annular part, 2n+1 (n=1, 2, 3...) is formed in the part corresponding to one magnetic pole.
This results in periodic changes in magnetic flux.

Further, a printed circuit board (not shown) is disposed so as to face the side surface of the annular portion of the rotor 2 on which the groove portion 2A is provided, and the groove portion 2A is provided on one surface facing the printed circuit board (not shown).
A plurality of power generation line elements 3 are arranged radially at the same pitch as the groove portion 2A facing the groove 2A, thereby forming a power generation coil connected in series in a zigzag pattern. Note that this power generation coil is fixed as appropriate.

In such a configuration, when the rotor 2 rotates concentrically with respect to the power generating line element 3 as the rotating shaft rotates,
A voltage is induced in the power generation line element 3 due to a change in the strength of the magnetic field passing through the power generation line element 3 due to a change in the magnetic flux obtained in the groove portion 2A. Then, the voltage integrated (added) over the entire circumference of the power generation line element 3 from the output terminal of the power generation coil is output as a frequency signal corresponding to the rotation speed of the rotor 2.

Here, the change in magnetic flux is determined by the driving multipole magnet 1.
2n+1(n
= 1, 2, 3, ...) periodic magnetic flux changes occur. In addition, in the example shown in Figure 1, 11
This causes a periodic change in magnetic flux.

Next, the operation shown in FIG. 1 will be explained in detail using FIG. 2. A and B in Figure 2
1 is a circumferential cross-sectional view of the power generating line element 3 and the rotor 2, and C is a diagram showing a simplified state of change in the magnetic flux passing through the power generating line element 3, replacing it with a switching operation. In this FIG. 2C, in reality, the magnetic flux changes slowly at the boundaries of the magnetic poles in the magnetization of the rotor 2, and does not change rapidly as shown in the figure. In addition, in A of Figure 2, the direction of the induced voltage can be expressed as (from the front to the rear of the drawing) or

Claims (1)

[Claims] 1. A rotor having an annular portion made of a magnetic material and arranged around the outer periphery of the multi-polar driving magnet is attached to a multi-polar driving magnet that is fixed to a rotating shaft and is freely rotatable and magnetized in sections in the circumferential direction. A plurality of uneven parts are formed at the same pitch by radial grooves on one side of the annular part, and the grooves corresponding to the S and N poles of the driving multipolar magnet are electrically connected. The corner is shifted by 180 degrees, and the boundary between the S and N poles is made so that a series of convex parts and a series of concave parts alternate, and the annular part magnetized by the magnetic pole of the multi-pole drive magnet has one magnetic pole. The periodic magnetic flux is changed 2n (n=1, 2, 3...) times in the part corresponding to A frequency generator characterized by a fixed arrangement of generating coils connected in series.