JPS6110169Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a magnetic substance detection element using self-mononucleated magnetic lines, and is particularly suitable for detecting the rotational speed of a rotating magnetic disc with teeth formed around the periphery. Regarding elements.

As shown in FIG. 1, the self-mononucleated magnetic line is a strong magnetic line that has been treated to have a central core 1 with a relatively small coercive force in the center and an outer shell 2 with a relatively large coercive force around it. It is a magnetic wire. To magnetize the outer shell 2, it is necessary to apply a magnetic field of about 30 oersted or more, and the core 1 has a relatively low coercive force, so about 10 oersted
Magnetization is reversed in a magnetic field below Oersted. The self-mononucleated magnetic line is in a magnetized state when the outer shell 2 and the central core 1 are magnetized in the same direction, and the outer shell 2 and the central core 1 are magnetized in opposite directions. In some cases, a cylindrical magnetic domain is permanently formed, resulting in a demagnetized state.

When a coil is provided around the self-mononucleated magnetic wire as described above and an alternating symmetrical magnetic field as shown in FIG. When changing from a magnetized state to a demagnetized state, a pulsed voltage is induced in the coil as shown in FIG. 2B.

By the way, when the above-mentioned alternating symmetrical magnetic field is applied to the self-mononucleating magnetic line, bipolar pulse voltages with equal amplitude can be obtained, but the amplitude of the pulse voltage is about 0.5V, which is not very large. However, if only a unidirectional pulse voltage is used, this is disadvantageous in terms of signal-to-noise ratio or when directly triggering a switching element such as a thyristor.

In view of the above points, the present invention aims to provide a magnetic substance detection element that can extract a unidirectional pulse voltage of sufficiently large amplitude by applying an alternating asymmetric magnetic field to self-mononucleated magnetic lines. be.

Embodiments of the magnetic substance detection element according to the present invention will be described below with reference to the drawings.

3 and 4 show a first embodiment of the present invention. In these figures, a rotating magnetic disc 3 is shown as an object to be detected, and teeth 4 and grooves 5 are alternately formed on the periphery of the rotating magnetic disc 3. On the other hand, the magnetic body detection element 10 includes a self-nucleating magnetic wire 11, a coil 12 wound around the self-nucleating magnetic wire 11, and an L connected to the rear end of the self-nucleating magnetic wire 11.
It consists of a letter-shaped yoke 13, a first permanent magnet 14, and a second permanent magnet 15. The first permanent magnet 14 applies a magnetic field strong enough to magnetize both the outer shell and the central core of the self-uninucleating magnetic line 11, and is arranged in parallel to the self-uninucleating magnetic line 11. It will be arranged as follows. Further, the second permanent magnet 15 is attached to the tip of the L-shaped yoke 13, and a gap G is formed between the tip of the self-mononucleated magnetic wire 11 and the tip of the second permanent magnet 15. . Here, when a magnetic body is present in the air gap G, the second permanent magnet 15 cancels the magnetic field of the first permanent magnet 14 and applies an asymmetrical magnetic field in the opposite direction to the self-mononuclear magnetic line 11. It is something.

In the configuration of the first embodiment described above, when the rotating magnetic disk 3 rotates as shown by the arrow A by the rotating shaft 20, the teeth 4 and the grooves 5 pass through the gap G of the magnetic detecting element 10 as shown in FIG. 5A. pass alternately. Here, when the groove 5 is located in the air gap G, the second permanent magnet 1
Since the influence of 5 can be ignored, as shown in FIG. 5B, a sufficiently large magnetic field by the first permanent magnet 14
direction is applied to the self-mononucleating magnetic line 11, and both its outer shell and central core are magnetized. At this time, Figure 5C
A pulse voltage of about 2.5V with a sufficiently large amplitude is generated in the coil 12 as shown in FIG. Next, when the tooth 4 is located in the gap G, the N pole of the second permanent magnet 15, the yoke 13, the self-nucleating magnetic line 11, the tooth 4, the second
A magnetic path is formed by the path of the S pole of the permanent magnet 15,
As shown in FIG. 5B, the magnetization of the central nucleus is reversed by a weak magnetic field in the direction of arrow C. At this time, Figure 5C
As shown in the figure, the pulse voltage of small amplitude is reverse polarity and
2.

According to the first embodiment, two permanent magnets 14 and 15 that apply mutually opposite magnetic fields to the self-nucleated magnetic line 11 are combined, and the rotating magnetic disc 3 as the object to be detected is Since an asymmetrical magnetic field is applied to the self-mononucleating magnetic line 11 depending on the presence or absence of the teeth 4, it is possible to extract a pulse voltage with a sufficiently large amplitude corresponding to the number of passing teeth 4 on a one-to-one basis. . Therefore, the rotation angle or rotation speed of the rotating magnetic disc 3 can be detected under a good signal-to-noise ratio. Furthermore, when applied to an automobile ignition system, etc., there is an advantage that a thyristor or the like can be directly ignited with a pulse voltage.

FIG. 6 shows a second embodiment. In this diagram,
The magnetic body detection element 10A has a self-mononuclear magnetic line 1
1, a coil 12 wound around the coil 12, and a first coil 12 disposed at the upper end of the self-nucleated magnetic wire 11.
permanent magnet 14 and an L-shaped first yoke 13A.
and a gap G at the lower end of the self-mononuclear magnetic line 11.
, and an L-shaped second yoke 13B that faces the lower end of the first yoke 13A with a gap G' in between. Then, the gaps G and G' are connected to the teeth 4 of the rotating magnetic disk 3.
The magnetic body detection element 10A is arranged so as to cross the magnetic body detection element 10A.

In the configuration of the second embodiment described above, when the rotating magnetic disc 3 is rotated by the rotating shaft 20 in the direction of the arrow A, as shown in FIG. The teeth 4 and the grooves 5 alternately pass through. Here, when the tooth 4 is located within the gaps G and G',
N pole of the first permanent magnet 14, first yoke 13A,
Since a magnetic path is constituted by the path of the tooth 2, the self-nucleating magnetic line 11, and the S pole of the first permanent magnet 14, the seventh
As shown in FIG. B, a sufficiently large magnetic field by the first permanent magnet 14 is applied to the self-nucleating magnetic line 11 in the direction of arrow D, and both its outer shell and central core are magnetized.
At this time, as shown in FIG. 7C, a sufficiently large pulse voltage of about 2.5V is generated in the coil 12. Next, when the groove 5 is located in the gaps G and G', the N pole of the second permanent magnet 15, the second yoke 13B, the first yoke 13A, the first permanent magnet 14, the self-nucleated magnetic line 11, and the A magnetic path is formed along the path of the S pole of the second permanent magnet 15, and the magnetization of the central core is reversed by a weak magnetic field in the direction of arrow E, as shown in FIG. 7B. At this time, as shown in FIG. 7C, a pulse voltage of small amplitude is generated in the coil 12 with opposite polarity.

The second embodiment described above can also achieve the same effects as the first embodiment described above.

FIG. 8 shows a third embodiment. In this diagram,
The magnetic body detection element 10B has a U-shaped yoke 1 by omitting the gap G' of the magnetic body detection element 10A in FIG.
3C is used, and the other parts are the same as the magnetic body detection element 10A. If the teeth 4 of the rotating magnetic disk 3 cross the gap G of the magnetic body detection element 10B, when the teeth 4 are located in the gap G, the magnetic field in the direction of the arrow F caused by the first permanent magnet 14 is self-directed. The groove 5 joins the single nucleation magnetic line 11, and the groove G
When located inside, a magnetic field from the second permanent magnet 15 in the direction of arrow H is applied. Therefore, the relationships among the disk position, magnetic field, and pulse voltage are as shown in FIGS. 7A, B, and C, the same as in the second embodiment.

In each of the above embodiments, the rotating magnetic disk 3 is shown as the object to be detected, but it is of course possible to detect a magnetic plate with linearly arranged teeth, a magnetic body that moves reciprocally, etc. be.

As described above, according to the present invention, a magnetic substance detection element is obtained which can obtain a unidirectional pulse voltage with a sufficiently large amplitude by applying an alternating asymmetric magnetic field to a self-mononucleated magnetic line.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing a self-mononucleating magnetic line, Fig. 2 is a waveform diagram showing the effect when an alternating symmetrical magnetic field is applied to the self-mononucleating magnetic line, and Fig. 3 is a magnetic body according to the present invention. A plan view showing a first embodiment of the detection element,
FIG. 4 is a side view of the same, FIG. 5 is an explanatory view showing the operation of the first embodiment, and FIG. 6 is a side view showing the second embodiment.
FIG. 7 is an explanatory view showing the operation of the second embodiment, and FIG. 8 is a side view showing the third embodiment. 1...Central core, 2...Outer shell, 3...Rotating magnetic disc, 4...Teeth, 5...Groove, 10, 10A, 10
B... Magnetic substance detection element, 11... Self-mononucleated magnetic wire, 12... Coil, 13, 13A to 13C
... Yoke, 14, 15 ... Permanent magnet, G,
G′...Void.

Claims (1)

[Scope of utility model registration request] a self-nucleated magnetic wire, a coil wound around the self-nucleated magnetic wire, an outer shell of the self-nucleated magnetic wire, a first permanent magnet for magnetizing the central core, and a first permanent magnet for reversing the magnetization of the central core. a yoke forming a part of a magnetic path for applying a magnetic field by the second permanent magnet to the self-mononucleated magnetic line; and a detected object provided at least at one location in the magnetic path. 1. A magnetic substance detection element comprising: a gap through which a magnetic substance passes through.