JPH03243832A - Magnetic circuit using magnetostrictive pulse generating element - Google Patents

Abstract

PURPOSE:To miniaturize this magnetic circuit by arranging plural yokes outside the magnetostrictive pulse generating element at intervals and coupling their one-terminal sides with the element, and arranging a permanent magnet which applies a magnetic field to one of them at the other end of the element. CONSTITUTION:The magnetostrictive pulse generating element (WIEGAND element) 10 is provided between 1st and 2nd yokes 21 and 22, which are arranged in parallel at a specific interval and have one-end sides coupled mutually, in parallel and their one-end sides are coupled with the coupling parts of the yokes 21 and 22. At the other-end sides, the permanent magnet 1 is supported in an up-down movable state. When the magnet 1 is moved and its N pole approaches the yoke 21, a magnetic path is formed while penetrating the yoke and element 10, and the magnetization direction of the internal core part 11 is inverted abruptly to induce a voltage pulses in a detection coil 13. When the S pole of the magnet 1 approaches the yoke 22, on the other hand, the magnetization direction of the internal core part 11 is re-inverted abruptly to induce a reverse-directional pulse. Consequently, only one permanent magnet 1 is required and the circuit is reduced in cost and size; and displacement/output characteristic setting with an external force is facilitated and the degree of freedom can be increased.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic circuit using a magnetostrictive pulse generating element.

Prior art and its problems A magnetostrictive pulse generating element outputs an electric signal by inducing a voltage by changing the direction of a magnetic field applied from a permanent magnet or the like. Specific examples of the magnetostrictive pulse generating element include a so-called Wiegand effect device such as permalloy (50Ni-50Fe), an amorphous magnetostrictive wire that produces a large Barkhausen effect or a Matteucci effect, and the like.

A Wiegand wire is an example of a Wiegand effect device. This Wiegand wire is obtained by heat-treating a semi-hard magnetic material while stretching it, and making the coercive force different between the inner core and the outer shell.

When a detection coil is wound around the Wiegand wire, positive and negative pulse signals are generated at both ends of the detection coil when the magnetic field of the Wiegand wire is reversed. Conventionally, pulses are generated in such a magnetostrictive pulse generating element by reversing the magnetic field using two permanent magnets, one for saturation and one for reset.

However, since two magnets are required, it is relatively expensive and it is difficult to achieve miniaturization.

SUMMARY OF THE INVENTION OBJECTS OF THE INVENTION An object of the present invention is to provide a magnetic circuit using a magnetostrictive pulse generating element that uses one permanent magnet and can be miniaturized.

Structure 1 of the Invention Functions and Effects A magnetic circuit using the magnetostrictive pulse generating element according to the present invention includes a magnetostrictive pulse generating element, which is arranged at intervals outside the magnetostrictive pulse generating element, and one end of each of which is arranged outside the magnetostrictive pulse generating element at intervals. A plurality of yokes coupled to one end of the pulse generating element and the other end of the magnetostrictive pulse generating element are arranged so as to be relatively movable at intervals, and the magnetostrictive pulse generating element and the above are connected according to relative positions. It is characterized by comprising a permanent magnet that applies a magnetic field to at least one of the yokes.

According to this invention, a magnetic field generated from a permanent magnet is applied to a yoke corresponding to the relative position of the magnetostrictive pulse generating element and the permanent magnet, so that a magnetic path is formed by the magnetostrictive pulse generating element and the yoke. A plurality of magnetic paths can be formed by the plurality of yokes, and are selectively formed depending on the position of the permanent magnet. When the permanent magnet changes relative to the magnetostrictive pulse generating element and the yoke, the magnetic path formed changes, and the direction of magnetization of the magnetostrictive pulse generating element changes. As a result, a pulse signal is output from the magnetostrictive pulse generating element.

According to the present invention, since only one permanent magnet is required, it can be provided at low cost and is advantageous for miniaturization, and the displacement/output characteristics by one external force can be easily set and the degree of freedom is increased.

In addition, the magnetic path of the magnetostrictive pulse generating element is formed using a yoke, and the magnetostrictive pulse generating element is configured to output a pulse signal by reversing the direction of the magnetic field in the magnetic path, so that magnetostrictive pulse generation is possible. The element can be magnetically shielded, making it resistant to magnetic disturbances. Furthermore, even if the relative displacement of the permanent magnet is minute, a pulse signal output can be obtained, so displacement can be detected with high precision.

The magnetic circuit according to this invention can be used for displacement sensors, vibration sensors,
It can be widely applied to non-contact switches, etc.

Description of examples FIG. 1 is a perspective view showing an embodiment of this invention.

The magnetic circuit is the first yoke 21. The second yoke 22 is composed of a Wiegand element 10 and a permanent magnet 1.

The first yoke 21 and the second yoke 22 are arranged parallel to each other with a predetermined distance apart, and are connected to each other at one end. First yoke 21 and second yoke 22
The other end is open.

The Wiegand element 10 is provided in parallel with the first yoke 21 and the second yoke 22 with an interval between them.

One end of the Wiegand element IO is coupled to the coupling portion of these yokes 21 and 22. The other end of the Wiegand element 10 extends to near the other end of the yoke 21, 22.

Wiegand element (magnetostrictive pulse generating element) 10 has an inner core 11 and an outer shell (cladding) surrounding the inner core 11
12, and the outer shell portion 12 has a larger coercive force. As a specific example of the magnetostrictive pulse generating element, for example, Picaloy (IOV52Co-38Fe) (
Product name: Wiegand wire), permalloy (50N
The so-called Wiegand effect devices such as i-50Fe), the Barkhausen effect, and Mat
Examples include amorphous magnetostrictive wires that produce the teucci effect.

A coil 13 is wound around such a Wiegand element 1O in order to extract a voltage pulse generated when the magnetic pole is reversed. There are various ways to extract the voltage pulses other than winding the coil 13.

Permanent magnet 1 is arranged in front of the other ends of Wiegand element 10 and yokes 21 and 22. The permanent magnet 1 is supported by a support mechanism (not shown).

It can be moved up and down as shown by the arrow.

Figures 2 (A) and (B) are side views of the magnetic circuit shown in Figure 1, and Figures 3 (A) and (B) are views of the magnetic circuit shown in Figure 2 (A) and (B). Wiegand element 1
The pulses generated in the detection coil 13 when the magnetization direction of the inner core portion 11 of 0 is reversed are shown.

As shown in FIG. 2(B), the Wiegand element 1° has an inner core portion 11. It is assumed that both the outer shell portion 12 are magnetized in the same direction.

In this state, as shown in FIG. 2(A).

When an upward external force is applied to the magnet 1 and the N pole of the magnet 1 approaches the first yoke 21, a magnetic path is formed through the yoke 21 and the Wiegand element 10, and the magnetization direction of the inner core 11 is rapidly reversed. The outer shell 12 is not inverted due to its strong coercive force. This induces a voltage pulse in the detection coil 13 as shown in FIG. 3(A).

Next, as shown in FIG. 2(B), when a downward external force is applied to the permanent magnet 1 and the S pole of the permanent magnet 1 approaches the second yoke 22, the lower yoke 22 and the Wiegand element lO generate a magnetic field. A path is formed, and the magnetization direction of the inner core portion 11 suddenly returns to its original state. As a result, as shown in FIG. 3(B), a voltage pulse in the opposite direction to the voltage pulse shown in FIG. 3(A) is induced.

FIG. 4 is a perspective view showing another embodiment.

In this example, the top and bottom of the Wiegand element IO.

The first yoke 21. is located at the left and right positions. The second yoke 22°, the third yoke 23, and the fourth yoke 24 are arranged. These yokes 21 to 24 and Wiegand element 10 are coupled at one end thereof. Furthermore, the permanent magnet 1 supported in front of the other ends of the Wiegand element 10 and the yokes 21, 22, 23 and 24 is
It has a large number of north and south poles corresponding to ~24. This permanent magnet 1 is also supported by a support mechanism (not shown), and is movable vertically and horizontally as shown by arrows.

When the permanent magnet 1 moves vertically or horizontally in response to an external force, one of the yokes 21, 22, 23 and 24 and the magnetostrictive pulse generating element 10 form a magnetic path. As a result, the magnetization in the inner core of the pulse generating element 10 is reversed, and a voltage pulse can be extracted from the detection coil 13 in the same manner as in the embodiment described above.

In the embodiments described above, the permanent magnet is movable and the Wiegand element is fixed, but the permanent magnet may be fixed and the Wiegand element movable.

[Brief explanation of drawings]

Figure 1 is a perspective view showing an embodiment of this invention, Figure 2 (A)
, (B) is a side view for explaining the operation of the Wiegand element, Figure 3 (A), (B) is Figure 2 (A)
FIG. 2 is a waveform diagram showing pulses generated by the magnetization changes shown in FIGS. FIG. 4 is a perspective view showing another embodiment. 1...Permanent magnet. 10... Wiegand element. 21, 22. 23. 24...York. Above Figure 2 (A) 1 CB) 1 and 2 Figure 3 (A) CB)

Claims (1)

[Claims] a magnetostrictive pulse generating element, a plurality of yokes arranged at intervals outside the magnetostrictive pulse generating element, each having one end coupled to one end of the magnetostrictive pulse generating element; A magnetostrictive pulse generating element is used, the magnetostrictive pulse generating element having a permanent magnet disposed at the other end so as to be relatively movable with an interval, and applying a magnetic field to at least one of the magnetostrictive pulse generating element and the yoke depending on the relative position. magnetic circuit.