JP2014171044A - Electrical pulse generation apparatus and electrical pulse generation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To induce an electrical pulse responsively to a slight change in an exciting external magnetic field by improving a basic technique of electrical pulse generation using a composite magnetic wire so as to increase electrical pulse induction sensitivity.SOLUTION: A composite magnetic wire designated as 1 comprises a hard core 2 with a higher coercive force and a soft layer 3 with a lower coercive force formed as a center part and an outer layer part, respectively. For increasing the sensitivity of an electrical pulse generation apparatus having such a composite magnetic wire as an element, the soft layer 3 has a ring groove portion 8 formed therein.

Description

  The present invention relates to a technique for generating an electric pulse by utilizing a sudden magnetization reversal phenomenon caused by a large Barkhausen jump phenomenon of a composite magnetic wire and using the electric pulse as an energy harvest.

  Japanese Patent Application Laid-Open No. 2010-111010 cited as Patent Document 1 discloses a technique in which an electric pulse is generated by utilizing a sudden magnetization reversal phenomenon caused by a large Barkhausen jump phenomenon of a composite magnetic wire and the electric pulse is used as an energy harvest. Explained. The main points are described below.

For example, a thin wire obtained by drawing bicalloy (ferromagnetic material of Fe 40%, Co 50%, V 10%) has a unique magnetic property.
When twisting stress is applied to the wire, the wire is twisted more in the vicinity of the outer layer portion and less twisted in the inner core portion. Therefore, the magnetic properties are different between the outer layer portion and the inner core portion.
When processing is performed to leave this state, a ferromagnetic magnetic wire having different magnetic characteristics between the outer layer portion and the inner core portion can be obtained. This is called a composite magnetic wire.

The outer layer of the composite magnetic wire changes its magnetization direction with a relatively small magnetic field (coercivity,
That is, the coercive force is small). This outer layer is called the soft layer.
The inner core of the composite magnetic wire does not change the magnetization direction unless a relatively large magnetic field is applied (the coercive force and coercive force are large). The inner core is named a hard core.
FIG. 2A is a schematic cross-sectional view of a composite magnetic wire, in which dense spots are attached to locations with a large coercive force and dilute spots are attached to locations with a low coercivity.
The inner core portion denoted by reference numeral 2 is a hard core having a large coercive force, and the outer layer portion denoted by reference numeral 3 is a soft layer having a small coercive force.

When the above-described composite magnetic wire is excited by applying a magnetic field from the outside and the strength is higher than the coercive force of the hard core, the entire composite magnetic wire 1 is magnetized as shown in FIG.
In this example, both the soft layer 3 and the soft layer 2 are formed with magnetism facing right in the figure.
The additional arrow indicates the direction of magnetization (only the direction of magnetism is indicated, and the intensity of magnetization is irrelevant).
The added letters N and S represent the North Pole and the South Pole.
The soft layer is indicated by reference numeral (3). In this cross-sectional view, the upper soft layer 3 and the lower soft layer appear to be separated from each other. However, the outer layer portion of the composite magnetic wire 1 is entirely a soft layer, and when considered in three dimensions, the soft layer Are connected around two hard cores. For this reason, the usual soft layer “3” is attached to the upper soft layer, and the parenthesis “(3)” is attached to the lower soft layer for reference.

When a weak leftward magnetic field is applied to the composite magnetic wire 1 magnetized rightward as shown in FIG. 2 (B), the magnetic field for excitation is gradually increased.
When the strength of the excitation magnetic field exceeds the coercivity of the soft layer 3, the magnetism of the soft layer is reversed to the left. However, until the exciting magnetic field reaches the coercive force of the hard core 2, the magnetism of the hard core is not reversed and remains right, as shown in FIG.
Even if the external excitation magnetic field is removed from this state, the magnetization direction of the soft layer is held down by the magnetization of the hard core, and the magnetization state is stable. The exciting magnetic field at this time is called a set magnetic field.

Next, an external magnetic field for excitation is applied in the direction opposite to the set magnetic field to increase the external magnetic field. When the strength of the external magnetic field exceeds a certain critical strength, the magnetization direction of the soft layer is reversed, as shown in FIG. The exciting magnetic field at this time is called a reset magnetic field.
As a result, the magnetization directions of the soft layer and hard core are the same, and the initial state is restored.
The reversal phenomenon of the soft layer shown in Fig. 2 (B)-> (C) and (C)-> (D) described above, the magnetic wall of the soft layer moves in an avalanche-like state and magnetizes in an instant. Inversion occurs.
The phenomenon that the magnetization state reverses in the avalanche is called a large Barkhausen jump. The rate of magnetization reversal depends only on this large Barkhausen jump and is independent of the external magnetic field.

The case described above with reference to FIG. 2 is the case where an external magnetic field for excitation is applied to the entire length direction (that is, the axial direction) of the composite magnetic wire 1, but only in one part in the length direction. The magnetic reversal phenomenon of the soft layer can be caused partially by applying an external magnetic field.
FIG. 3A is a schematic cross-sectional view of a composite magnetic wire, and arrows indicate the magnetization directions.
This state corresponds to FIG. 2B described above, and both the hard core 2 and the soft layer are magnetized rightward in the drawing.
An area of the length direction dimension L is set in the vicinity of the center in the length direction, is named an inversion area, and is denoted by reference numeral 4.

An alternating magnetic field in the length direction is applied to the inversion area. That is, in the figure, a rightward excitation external magnetic field and a leftward excitation external magnetic field are alternately applied.
FIG. 3B illustrates how to apply an alternating magnetic field. Two exciting magnets 6 and exciting magnets 7 are arranged in parallel to the axial direction so as to face and separate from the composite magnetic wire 1.
These two magnets for excitation have their polarities opposite to each other. When these two magnets are alternately moved as indicated by the reciprocating arrows u and d and the “position closest to the composite magnetic wire” is changed, an alternating magnetic field is applied to the inversion area of the composite magnetic wire 1.
Although not shown, one electromagnet may be used instead of the two exciting magnets.
In this case, an alternating magnetic field can be applied by reversing the energization direction.
When the exciting magnet is used, the strength of the magnetic field is adjusted by “the distance between the composite magnetic wire and the exciting magnet”. In the case of an electromagnet, it is adjusted by the magnitude of the current.

In the state shown in FIG. 3A, when a magnetic field intensity is gradually increased by applying an excitation external magnetic field facing leftward to the inversion area 4, when the coercive force of the soft layer 3 is exceeded, FIG. As shown in C), the magnetism of the soft layer 3 is reversed at once in the reversal area 4 (a large Bauhaushausen jump).
Although not shown in the figure, an electric pulse can be obtained by arranging a detection coil in the vicinity thereof.
The arrangement of the detection coil is detailed in Japanese Patent Application Laid-Open No. 2010-111010 cited as Patent Document 1.
From the state of FIG. 3 (C), when an external magnetic field for excitation is applied to the right and the magnetic field is gradually increased, the soft layer in the reversal area 4 where the magnetism has been reversed is reversed again (a large Bauhaushausen jump). To restore the state of FIG.

JP 2010-111010 A

As illustrated in FIG. 3 above, if the magnetic reversal of the soft layer is performed by limiting the area of the composite magnetic wire, it is effective for detecting the relative position change between the composite magnetic wire and the exciting magnet. In addition, it is expected to contribute to the development of mechatronics because a sharp electric pulse can be obtained without depending on the speed of position change.
On the other hand, IT-related equipment is being reduced in size and weight, and electronic parts are being downsized in conjunction with advances in precision processing technology.
In view of these circumstances, the present inventors have improved the basic technology of generating electric pulses by using a composite magnetic wire and have pursued the improvement of electric pulse induction sensitivity.
An object of the present invention is to provide a basic configuration for inducing an electric pulse sensitively by a minute change of an external magnetic field for excitation.

The configuration of the invention according to claim 1 includes a composite magnetic wire having an outer layer portion having a relatively small coercive force and an inner core portion having a relatively large coercive force, means for applying an alternating magnetic field to the composite magnetic wire, and In the electric pulse generator having a detection coil in which an electric pulse is induced by the magnetic change of the composite magnetic wire,
A part of the outer layer portion has a shape removed in a ring groove shape.

In the present invention, the above-mentioned “relatively large and small” refers to a relative magnitude relationship between the coercive force of the soft layer, which is the outer layer part of the composite magnetic wire, and the coercive force of the inner core part.
The above “ring groove shape” is a phrase for imagining the shape, and refers to a circumferential groove common to a ring groove provided in a piston of an reciprocating engine or a ring groove for mounting an O-ring.
The ring groove in the present invention does not need to have a geometrically accurate shape, and may have an irregular taper on the side surface of the groove or a radius on the edge of the groove. There may be irregularities on the inner surface.
Further, the ring groove may be a so-called C-shape (a partially lacking ring shape) in which the ring groove does not form a complete ring shape. In short, a local small-diameter portion may be formed.
(Reference) Examples of the C-shaped (partially ring-shaped) member called a “ring” include a piston ring and a snap ring (retaining ring).

  The structure of the invention according to claim 2 is characterized in that, in addition to the constituent elements of claim 1, the bottom surface of the partially removed ring groove-like part reaches the vicinity of the inner core part.

The configuration of the invention according to claim 3 is in addition to the configuration requirements of claim 1 or claim 2,
A plurality of the removed ring groove-like portions are provided.

In addition to the constituent features of the first to third aspects, the configuration of the invention according to claim 4 includes:
The composite magnetic wire is made of Baicalloy.

The configuration of the invention according to claim 5 is in addition to the configuration requirements of claims 1 to 4,
The ring groove-shaped portion is removed by an etching process.

The configuration of the invention according to claim 6 is in addition to the configuration requirements of claims 1 to 5,
The ring groove-like portion is characterized by being partially missing in the circumferential direction without surrounding 360 degrees around the composite magnetic wire.

The invention method according to claim 7 comprises:
Configuring a composite magnetic wire having an outer layer portion having a relatively small coercive force and an inner core portion having a relatively large coercive force, and applying an alternating magnetic field to the composite magnetic wire;
In the method of generating an abrupt magnetization reversal phenomenon due to a large Barkhausen jump phenomenon in the outer layer portion of the composite magnetic wire and generating an electric pulse by this magnetization reversal phenomenon,
A ring-shaped groove is formed in advance in the outer layer portion of the composite magnetic wire.

  When the invention device according to claim 1 is applied, a minute change in the external magnetic field for excitation is smaller than that of the conventional composite magnetic wire type electric pulse generator in which the outer layer portion is not shaped like a ring groove. As a result, the soft layer of the outer layer causes magnetic reversal, so that an electric pulse can be detected sensitively.

  When the invention device according to claim 2 is applied, the bottom surface of the ring groove-shaped portion partially removed reaches the vicinity of the inner core portion. That is, since the soft layer of the outer layer portion is sufficiently removed in the radial direction, the magnetic reversal of the soft layer is performed sensitively and reliably, and the operation reliability of the apparatus is high.

  When the invention device according to claim 3 is applied, since there are a plurality of ring groove-like portions, a plurality of detection coils are provided corresponding to the plurality of ring groove-like portions to obtain a plurality of electric pulses. be able to.

  When the invention device according to claim 4 is applied, the composite magnetic wire which is a main essential component is composed of bicalloy having a unique magnetic property. The layer surely causes magnetic reversal, and the operation reliability of the device is high.

When the invention device according to claim 5 is applied, a part of the soft layer is removed in a ring groove shape by etching,
A minute ring groove can be configured with high accuracy, high efficiency, and low cost, and a high-quality electric pulse generator can be supplied in large quantities and at low cost.

  When the invention device according to claim 6 is applied, even if the ring groove-like recesses are not formed on the entire circumference of the composite magnetic wire, the “external magnetic field for excitation is minute”. The effect is that magnetic reversal occurs in the soft layer in response to a slight change, and electrical pulses can be detected.

  Since the ring-shaped groove is formed in the outer layer portion of the magnetic wire when the method of the invention according to claim 7 is applied, the “composite magnetic wire not having the shape in which the outer layer portion is removed in the ring groove shape” is used. Compared to the conventional method of generating electric pulses, a slight change in the excitation external magnetic field causes the soft layer of the outer layer to invert the magnetism, and the electric pulses are induced with sensitivity.

It is a schematic diagram of the composite magnetic wire in one Embodiment of this invention, Comprising: The magnetism which arises in the soft layer of an outer layer part and the hard core of an inner core part is represented by the arrow. The composite magnetic wire is shown, (A) is a schematic cross-sectional view, and (B), (C) and (D) are image diagrams showing the magnetization state. 1 shows an example in which a magnetic reversal section 4 is set near the center with respect to the length direction of a composite magnetic wire, (A) is a schematic cross-sectional view showing magnetism with an arrow, and (B) is a schematic diagram with an excitation mechanism added. (C) is a typical sectional view in which magnetism is represented by an arrow. 1A is a schematic cross-sectional view of an embodiment, FIG. 1B is a schematic perspective view thereof, and FIG. 3C is a schematic perspective view of an application example.

(See FIG. 2 (A) and FIG. 4 (A) in comparison) FIG. 2 (A) is a conventional composite magnetic wire, and FIG. 4 (A) is a composite magnetic wire in one embodiment of the present invention. In FIG. 4A, reference numeral 4 denotes the inversion area described above.
In the present invention, the ring groove-shaped portion 8 is provided by selecting an area that is clearly shorter than the length dimension L of the inversion area 4.
In this embodiment, the soft layer in the area having a groove width of 1 mm was removed using an etching technique for semiconductor processing, and a ring groove portion 8 having the groove bottom reaching the hard core 2 was formed.
However, since the boundary between the hard core 2 and the soft layer 3 is not exactly clear, it is sufficient if the groove bottom reaches the vicinity of the hard core.
In short, as a result of the configuration, the ring groove-shaped portion 8 needs to be formed on the outer peripheral surface of the composite magnetic wire 1, and the ring groove-shaped portion may be formed by any means.

FIG. 4B is a perspective view of the composite magnetic wire in which the ring groove portion 8 is formed.
A high-performance electric pulse generator cannot be obtained unless the ring groove has an appropriate depth, but a corresponding effect (sensitivity improvement) can be obtained even if there is a slight depth compared to the appropriate depth. Therefore, even if the position of the groove bottom is intentionally shifted from the hard core surface, it belongs to the technical scope of the present invention.
FIG. 4C is a schematic perspective view of an application example. Even if the ring-shaped groove is not formed at 360 degrees around the entire circumference of the composite magnetic wire, a corresponding effect (sensitivity improvement) can be obtained as long as it is formed at one part of the periphery.

When a known etching technique is applied to the formation of the ring groove portion, a minute ring groove can be configured with high accuracy, high efficiency, and low cost, and a high-quality electric pulse generator can be manufactured in large quantities and at low cost. Can be supplied.
In addition, when the composite magnetic wire is made of bicalloy, which is a ferromagnetic material having a chemical composition of Fe 40%, Co 50%, and V 10%, the soft layer reliably causes magnetic reversal in response to changes in the external magnetic field for excitation. The operation reliability of the device is high.
(Note) Some alloys called bicalloy have chemical compositions slightly different from the above. In the present invention, bicalloy means an Fe—Co—V type ferromagnetic material and does not prevent the addition of a small amount of other additives (such as Cr).

FIG. 1 is a schematic view showing the magnetic change of a composite magnetic wire in one embodiment of the present invention, in which a hard core 2 is formed on the inner core portion of the composite magnetic wire 1 and a soft layer is formed on the outer layer portion. .
In FIG. 1A, both the hard core 2 and the soft layer 3 are magnetized in the right direction.
From this state, when an excitation external magnetic field facing leftward is applied to the inversion area 4 and the strength reaches the set magnetic field, the magnetism of the soft layer 3 in the inversion area 4 is inverted as shown in FIG. An electrical pulse is induced in a detection coil outside the figure.

When the excitation external magnetic field is further strengthened and the coercive force of the hard core is exceeded, the magnetism of the hard core in the inversion area 4 is also reversed as shown in FIG.
Next, when excitation is performed by applying a right external magnetic field, the magnetism of the soft layer 3 in the inversion area 4 is inverted again as shown in FIG. When the external magnetic field for excitation to the right is further strengthened and the coercive force of the hard core 2 is exceeded, the state shown in FIG.

Among the magnetic changes described above with reference to FIG. 1, when the magnetism of the soft layer 3 is reversed as in (A) → (B) and (C) → (D),
When the ring groove portion 8 is provided, the amount of change in the excitation external magnetic field required for reversal is small as compared with the conventional example having no ring groove portion.
The inventors of the present invention have confirmed the effect of the ring groove portion as described below.

(See FIG. 4 (A)) The composite magnetic wire used in the experiment is a bicalloy having a wire diameter of 0.25 millimeters and a wire length of 20 millimeters and a chemical composition of Fe 40%, Co 50%, and V 10%.
Using an etching technique for semiconductor processing, the soft layer 3 in the area having a groove width of 1 mm was removed to form a ring groove portion 8 in which the groove bottom reached the hard core 2.
FIG. 4C is a schematic perspective view of an application example in which a partial ring groove 9 is formed for effect comparison. In addition, although illustration is abbreviate | omitted, the composite magnetic wire without a ring groove part was also prepared as a comparative example.

Next, the inventors' experiments will be described with reference to FIG.
The exciting magnet 6 and the exciting magnet 7 are 3 × 3 × 5 millimeter NdFeB magnets,
The number of windings of the detection coil 5 was 300.
The magnetization direction of the exciting magnet is parallel to the line length direction of the composite magnetic wire, and an inversion area is formed in an area corresponding to the length dimension of the exciting magnet.
The strength of the exciting external magnetic field was changed by horizontally supporting the composite magnetic wire 1 and moving the exciting magnet in the vertical direction (reciprocating arrows u and d).

When the excitation magnet was gradually brought closer to the composite magnetic wire 1 and the "distance between the composite magnetic wire and the excitation magnet" was measured when an electric pulse was induced in the detection coil,
18 mm in the case of a composite magnetic wire provided with a ring groove 8
In the case of the composite magnetic wire not provided with the ring groove portion 8, the thickness was 12 millimeters.
In the above experiment, it was confirmed that the magnetic field strength required for the magnetization reversal was reduced by providing the ring groove portion 8.
When the same measurement was performed on the composite magnetic wire having the partial ring groove 9 shown as the application example in FIG. 4C, the distance between the composite magnetic wire and the exciting magnet was 16 millimeters. When the all-around ring groove 8 is provided, a corresponding effect is recognized although it is inferior.

As described above, it is an experimental fact that the strength of the set magnetic field has decreased due to the formation of the ring groove-like portion, and this is a natural phenomenon with repetitiveness.
The mechanism of this phenomenon has not yet been completely clarified theoretically,
By providing a ring groove, a pseudo edge is formed on the soft layer,
It is considered that the domain wall can be moved even with a magnetic field strength equal to or lower than the set magnetic field in the conventional example having no ring groove portion.

DESCRIPTION OF SYMBOLS 1 ... Composite magnetic wire, 2 ... Hard core, 3 ... Soft layer, 4 ... Reversing zone, 5 ... Detection coil, 6 ... Excitation magnet, 7 ... Excitation magnet, 8 ... Ring groove Section. 9 ... Partial ring groove.

Claims (7)

A composite magnetic wire having an outer layer portion having a relatively small coercive force and an inner core portion having a relatively large coercive force;
And means for applying an alternating magnetic field to the composite magnetic wire, and an electric pulse generator having a coil in which an electric pulse is induced by a magnetic change of the composite magnetic wire,
An electric pulse generator characterized in that a part of the outer layer portion has a shape removed in a ring groove shape.   2. The electric pulse generator according to claim 1, wherein the bottom surface of the ring groove portion partially removed reaches the vicinity of the inner core portion.   The electric pulse generator according to claim 1 or 2, wherein a plurality of the removed ring groove-like portions are provided.   The electric pulse generator according to any one of claims 1 to 3, wherein the composite magnetic wire is made of Baicalloy.   The electric pulse generator according to any one of claims 1 to 4, wherein the ring groove portion is removed by an etching process.   The electric pulse according to any one of claims 1 to 5, wherein the ring groove part is partially missing in the circumferential direction without surrounding 360 degrees around the composite magnetic wire. Generator. A composite magnetic wire having an outer layer portion having a relatively small coercive force and an inner core portion having a relatively large coercive force
And applying an alternating magnetic field to the composite magnetic wire,
In the method of generating an abrupt magnetization reversal phenomenon due to a large Barkhausen jump phenomenon in the outer layer portion of the composite magnetic wire and generating an electric pulse by this magnetization reversal phenomenon,
An electric pulse generating method, wherein a ring-shaped groove is formed in advance in an outer layer portion of the composite magnetic wire.

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