JPH0283412A - Magnetic type rotation sensor - Google Patents

Abstract

PURPOSE:To obtain a detection characteristic of high resolving power, to enhance impact resistance and to reduce cost by mounting a strip like body made of amorphous magnetostriction material quality having a large number of holes bored therein at an equal interval in the rotary direction of a rotor to the outer peripheral part of the rotor and magnetically detecting the holes to detect the rotation of the rotor. CONSTITUTION:A strip like body 1 made of amorphous magnetostriction material quality having a large number of holes 2 bored therein at the predetermined equal interval corresponding to the detection resolving power of the rotational speed of a rotor part 10 is mounted to the outer peripheral part of the rotor part 10 in the same direction as the rotary direction of the rotor part 10. The magnetostriction parts 1a and holes 2 of the strip like body 1 are magnetically detected with the rotation of the rotor part 10 by a magnetic detection element 4 and the sine wave signal based on the rotation of said rotor part 10 is outputted from a detection part 20. Since the frequency of said sine wave signal is proportional to the number of rotations of the rotor part 10, the rotational speed or angle of rotation of the rotor part 10 is detected with high resolving power.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic rotation sensor that detects, for example, the rotation speed or rotation angle of a rotating shaft.

(Prior Art) A conventional magnetic rotation sensor includes, for example, a rotor made of a multi-pole magnetized magnet, and a magnetic detection section for magnetically detecting the rotation of the rotor arranged at a required interval from the circumference of the rotor. (Japanese Unexamined Patent Publication No. 62-25267, No. 62-26
No. 5522, No. 62-218816).

Other conventional magnetic rotation sensors include a toothed rotor made of a highly permeable magnetic material, and a magnetic detection section that magnetically detects the rotation of the rotor is arranged at a required interval from the circumferential surface of the rotor. (Unexamined Japanese Patent Publication No. 62-129716, No. 62-129716,
54119, 62-66116).

(Problems to be Solved by the Invention) In conventional magnetic rotation sensors that use a multi-polar magnetized magnet as a rotor, it is difficult to magnetize a limited area with high density and increase the number of magnetic poles. For this reason, it has been difficult to detect the rotation speed or rotation angle with high resolution. Also,
When considering cost reduction, it is desirable to make multi-polar magnetized magnets made of ferrite, but if made of ferrite, they are more likely to be damaged when subjected to external shocks, which may lead to a decrease in reliability. This made it difficult to reduce costs.

On the other hand, in other conventional magnetic rotation sensors that use a toothed rotor made of a highly permeable magnetic material, if the number of teeth is manufactured at a high density to achieve high resolution characteristics, the machining cost of the toothed shape increases. There was a problem that the cost would be high.

This invention was made based on the above circumstances, and an object of the present invention is to provide a magnetic rotation sensor that can obtain high-resolution detection characteristics, is resistant to shocks, has excellent reliability, and can further reduce costs. purpose.

[Nibe of the invention] (Means for solving the problems) In order to solve the above problems, the present invention includes a rotor, and a plurality of rotors attached to the outer circumference of the rotor and arranged at equal intervals in the rotational direction of the rotor. A belt-shaped body made of an amorphous magnetostrictive material with holes drilled therein and a part of the rotor where the belt-shaped body is attached are arranged at a required interval, and the rotation of the rotor is detected by magnetically detecting the holes. The gist is to have the means.

(Function) By employing chemical etching means or the like, a large number of holes in the strip can be formed with high precision at narrow, even intervals.

As the rotor rotates, holes in the strip and amorphous magnetostrictive portions corresponding to the spaces between the holes alternately cross the front surface of the detection means, and these holes or amorphous magnetostriction portions are magnetically detected by the detection means. Ru. As a result, the detection means outputs a periodic signal proportional to the rotation speed of the rotor, in other words, the interval between holes, and the rotation speed or rotation angle of the rotor can be determined with high resolution from the period of this output signal. detected.

A strip made of amorphous magnetostrictive material is more resistant to external shocks than ferrite, etc., so it has excellent reliability, and the drilling of multiple holes in this strip can be done as described above. Since chemical etching means, etc., which have relatively low processing costs, can be employed, costs can be reduced.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 to 5.

First, to explain the configuration of the magnetic rotation sensor, in FIG.
20 is a detection section as a detection means. As shown in FIGS. 2 and 4, on the outer circumference of the rotor section 10, a plurality of A belt-shaped body 1 made of an amorphous magnetostrictive material and having holes 2 formed therein is attached. The amorphous magnetostrictive material has a magnetic permeability that is about 7,000 to 8,000 times larger than that of air, and is preferably made of, for example, an iron-nickel light alloy to which boron and silicon are added. 1 in strip 1
a is an amorphous magnetostrictive portion (hereinafter simply referred to as magnetostrictive portion) corresponding to the space between the holes 2;

Although the outer circumferential surface of the rotor portion 10 in FIG. 2 has an arc shape, it is drawn as a straight line for convenience of explanation.

The detection unit 20 is disposed at a required interval from the attachment portion of the belt-shaped body 1 as described above in the rotor unit 10 .

As shown in FIG.
Two magnets 3a%3b with the same characteristics are arranged in parallel at a required interval in the same direction as the rotation direction of A magnetic detection element 4 for magnetically detecting the magnetostrictive portion 1a or the hole 2 in the body 1 is provided. And 2
The magnetic lines of force 5 generated by the magnets 3 a s 3 b pass through the magnetic detection element 4 . As the magnetic detection element 4, a Hall element, a magnetoresistive element, or the like is used. 6 is a sensor circuit, and this circuit has the function of activating the magnetic detection element 4, receiving a detection signal from the magnetic detection element 4, and converting it into a required signal.

Next, a method for manufacturing the rotor section 10 will be explained using FIGS. 3 and 4, and its structure will be explained in further detail.

A plastic frame 7, which becomes the main body of the rotor section 10, is manufactured by means such as injection molding (FIG. 3(A)). On the other hand, an amorphous magnetostrictive material strip 1 having a plurality of holes 2 formed at predetermined equal intervals is manufactured (FIG. 4). The plurality of holes 2 are precisely formed at predetermined equal intervals using, for example, a chemical etching method. Next, after wrapping and fixing this strip 1 around the frame 7 (FIG. 3(B)),
The frame body 7 and the band-shaped body 1 are integrated using a plastic injection molding method or the like to manufacture the rotor part 10 (see FIG. 3).
C)).

Next, the operation of the magnetic rotation sensor configured as described above will be explained using FIG. 5.

As the rotor part 10 rotates, the magnetostrictive part 1 in the strip body 1
a and the holes 2 alternately cross the front surface of the magnetic sensing element 4. FIG. 2(A) shows a state in which the magnetostrictive portion 1a is closest to the magnetic detection element 4. At this time, the magnetic lines of force 5 coming out from the magnets 3a and 3b are drawn toward the magnetostrictive portion 1a having a high magnetic permeability, and the proportion of the lines of magnetic force 5 passing through the magnetic detection element 4 is reduced to the minimum. As a result, the output of the detection section 20 outputted via the sensor circuit 6 becomes the lowest level as shown by point B in the output characteristics of FIG.

On the other hand, FIG. 2(B) shows a state in which the hole 2 is closest to the magnetic detection element 4. At this time, some of the magnetic lines of force 5 coming out of the magnets 3a and 3b are also drawn toward the magnetostrictive portion la, but the proportion of the lines of magnetic force 5 passing through the magnetic detection element 4 increases to the maximum value. As a result, the output of the detection section 20 reaches the maximum level as indicated by point A in the output characteristics of FIG.

In this way, as the rotor section 10 rotates, the magnetostrictive section 1a and the hole 2 in the strip 1 are magnetically detected by the magnetic detection element 4, and the detection section 20 outputs a sine wave signal based on the rotation. is output. Since the frequency of this sine wave signal is proportional to the rotation speed of the rotor section 10, the rotation speed or rotation angle of the rotor section 10 can be detected with high resolution from this frequency.

In addition, in the above-mentioned embodiment, two magnets 3 are provided in the detection unit 20.
Although magnets a and 3b are arranged in parallel, the number of magnets may be only one on the back side of the magnetic detection element 4. In this case, the output level of the sine wave signal taken out from the magnetic detection element 4 decreases depending on the number of magnets provided, but by taking measures such as increasing the amplification degree in the sensor circuit, the rotation of the rotor section can be reduced. The speed or angle of rotation can be detected with high resolution in much the same way as described above.

[Effects of the Invention] As described above, according to the present invention, a large number of holes in the strip can be formed with high precision at narrow equal intervals by employing chemical etching means or the like. Therefore, the period of the signal output from the detection means for magnetically detecting this hole is shortened, and the rotation speed or rotation angle of the rotor can be detected with high resolution. In addition, the amorphous magnetostrictive material type strip is more resistant to external shocks than ferrite, etc., so it can provide excellent reliability. As mentioned above, it is possible to use a chemical etching method that requires relatively low processing costs, so there is an advantage that costs can be reduced.

[Brief explanation of the drawing]

1 to 5 show embodiments of the magnetic rotation sensor according to the present invention. FIG. 1 is a block diagram showing the overall structure, and FIG. 2 is a block diagram showing an enlarged and cut away main part. , FIG. 3 is a process diagram showing an example of the manufacturing process of the rotor part, FIG. 4 is a perspective view of the band-shaped body part, and FIG. 5 is a signal waveform diagram showing the output signal of the detection part. 1: Amorphous magnetostrictive material strip, 2: Hole,
10: rotor section, 20: detection section (detection means). Agent Patent Attorney Yasuo Miyoshi Figure 3 (A) Figure 3 (B) Figure 3 (C) Figure 4 Figure 2 (A) Figure 2 (B) Figure 5

Claims (1)

[Claims] A rotor, a strip made of an amorphous magnetostrictive material that is attached to the outer circumference of the rotor and has a plurality of holes drilled at equal intervals in the rotational direction of the rotor, and a required interval between the attachment parts of the strip on the rotor. 1. A magnetic rotation sensor comprising: a detection means disposed at a distance from the rotor for magnetically detecting the hole and detecting rotation of the rotor.