JP2007225536A - Device for detecting rotary motion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for detecting rotary motion, using a simple structure requiring no large volume, for generating electrical pulses. <P>SOLUTION: The device for detecting rotary motion is provided with a magnetic wire having a coil wound around it, which causes large Barkhausen jumps, and rotates at least one permanent magnet. The device enables, by providing a magnetic field to only the portion of the wire, generation of electrical pulses by the coils which are wound round a portion of the magnetic wire. The device is also simple and requires no large volume for installation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rotational motion detection device to which an electric pulse generator using a large Barkhausen jump is applied.

Obtaining an electric pulse according to the rotation speed of a rotating object is required in various fields such as an automatic control field and electric and electronic devices. Conventionally, as an means for generating this kind of electric pulse, various types such as an optical type or a magnetic type have been developed and used as an encoder. One of them is an electric pulse generation using a large Barkhausen jump. There is a device.

This device is composed of magnetic wires, magnets, electric coils, etc., and the magnetic flux density in the magnetic material having magnetic anisotropy is changed by moving or replacing the magnetic field generating means such as magnets. A voltage is generated in an adjacent electric coil by electromagnetic induction, and this voltage is used as a pulse signal.

Generally, a rotational motion detection device using a magnetic sensor such as a Hall element or a magnetoresistive element requires a power source for driving a magnetic sensor such as a Hall element or a magnetoresistive element, and the signal obtained There is a need for a circuit to handle the above. However, the rotational motion detection device using the large Barkhausen jump can be operated without a power source, and since the output signal is a voltage pulse, the circuit for processing the signal is simple and requires low power consumption. In many cases, it is built into equipment.

The operation principle of a magnetic wire that can cause a large Barkhausen jump, which is the background art of the present invention, will be described. A ferromagnetic wire drawn into a thin wire has unique magnetic properties along with its alloy composition. When a twisting stress is applied to the wire, the wire is twisted more in the vicinity of the outer peripheral portion of the wire and less twisted in the central portion, so that the magnetic properties are different between the outer peripheral portion and the central portion. When processing is performed to leave this state, a ferromagnetic magnetic wire having different magnetic characteristics between the outer peripheral portion and the central portion can be obtained.

The magnetic properties of the outer periphery of the magnetic wire change its magnetization direction with a relatively small magnetic field. On the other hand, the magnetization direction of the central portion is changed by a magnetic field larger than that of the outer peripheral portion. That is, a composite magnetic body having two different magnetic properties, that is, an outer peripheral portion having a magnetic property that is relatively easily magnetized and a central portion that is difficult to be magnetized, is formed in one magnetic wire. Here, the outer peripheral portion is called a soft layer, and the central portion is called a hard layer.

Initially, the direction in which the hard layer and the soft layer of the magnetic wire are magnetized is not determined, and is in a discrete magnetization state. When an external magnetic field sufficient to reverse the magnetization direction of the hard layer is applied in parallel to the longitudinal direction of the magnetic wire, that is, the axial direction, the soft layer is naturally magnetized and aligned with the same magnetization direction. . Next, an external magnetic field that can magnetize only the soft layer is applied in the opposite direction. As a result, a magnetized state in which the magnetized direction is reversed between the soft layer and the hard layer of the magnetic wire is formed. Even if the external magnetic field is removed in this state, the magnetization direction of the soft layer is suppressed by the magnetization of the hard layer, and the magnetization state is stable. The external magnetic field at this time is called a set magnetic field.

Next, an external magnetic field opposite to the set magnetic field is applied 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 rapidly reversed. This magnetic field is called a critical magnetic field. In the reversal phenomenon at this time, the domain wall of the soft layer moves in a state where an avalanche is depressed, and magnetization reversal occurs instantly. As a result, the magnetization directions of the soft layer and the hard layer become the same, and the initial state is restored. The external magnetic field applies a magnetic field larger than the critical magnetic field. This magnetic field is called a reset magnetic field. The phenomenon that the magnetization state is reversed so as to pass through this avalanche is regarded as a large Barkhausen jump. The rate of magnetization reversal depends only on this large Barkhausen jump and is independent of the external magnetic field. When a large Barkhausen jump occurs, if an electric coil is installed in the vicinity of the composite magnetic wire, a voltage is generated by electromagnetic induction.

In the prior art, in order to generate the above-mentioned large Barkhausen jump, an electric pulse is generated by bringing two or more even number of permanent magnets close to the magnetic wire as the magnetic sensing element so that the magnetic poles are reversed. The generation was based on the principle of operation.

  For example, a magnetic sensor using a magnetic field generation method disclosed in Patent Document 1 is known as a rotational motion detection device using this operating principle. This pulse signal generator is shown in FIG. In FIG. 11, a disk on which two or more even-numbered magnets are mounted rotates by applying an alternating magnetic field to a magnetosensitive element capable of causing a large Barkhausen jump.

Another example of a rotational motion detection apparatus that applies a magnetic field to the entire magnetosensitive element is disclosed in Patent Document 2. The rotational motion detection device disclosed in Patent Document 2 is referred to as Conventional Example 2, and FIG. As shown in FIG. 12, the conventional example 2 is a magnet group in which two or more even-numbered magnets are arranged on the circumference as a magnetic field generation source so as to magnetize the entire magnetosensitive element that can cause a large Barkhausen jump. Two sets are provided, and the magnets at the shortest distance between them are rotated so that they attract each other, thereby alternating the direction of the magnetic field applied to the entire magnetic wire and inducing a large Barkhausen jump. It has a structure.

These rotary motion detectors have the advantage of being able to be powered off and can be used in place of conventional electromagnetic pickups and hall elements, with the advantage that a pulse output with a magnitude independent of the speed of rotation can be obtained. Is something that can be done.
Japanese Patent No. 2598453 JP 2005-114609 A

As shown in Conventional Example 1 or Conventional Example 2, in the conventional rotary motion detecting device applying the large Barkhausen jump, at least two or more permanent magnets are required and a plurality of permanent magnets are mounted. To do this, the disk needs to be large. Further, as shown in FIGS. 11 and 12, the disk on which the permanent magnet is mounted corresponds to apply an alternating magnetic field to the entire magnetosensitive element by rotating in a plane parallel to the direction of the center line of the magnetosensitive element. The distance between the magnetic poles of the permanent magnet is set to be longer than the length of the magnetosensitive element. For this reason, the disk on which the permanent magnet is mounted needs to be large.

In a device that applies the large Barkhausen jump, the positional relationship between the permanent magnet and the magnetic wire is very strict. If the distance between the permanent magnet and the magnetic wire is not appropriate, no pulse signal is output or double output is generated. There was a problem in the accuracy of the signal. In order to avoid this problem, it is desirable that the magnetic field applied to the magnetic wire has a small variation. In the conventional example, the distance between the permanent magnets is important, and it is necessary to accurately mount an even number of permanent magnets. .

Due to such problems, it is difficult to reduce the size of a rotational motion detection device using a large Barkhausen jump, and it is difficult to provide an inexpensive device. Furthermore, since a pair of two permanent magnets is required, it has been impossible to provide a rotary motion detection device that is small and has high resolution.

An object of the present invention is to provide a rotation detection device that generates an electric pulse with a simple configuration that does not require a large volume, and to make this type of rotation detection device applicable to a wider range of fields.

If the number of permanent magnets can be reduced in response to the demand for miniaturization, the overall volume can be reduced. Means for solving this problem is that a detection coil is partially wound around a magnetic wire, and one permanent magnet is placed on a plane parallel to the center line of the magnetic wire, and one side surface of the magnetic wire. It is a rotational motion detection device by relatively moving the vicinity and inducing a large Barkhausen jump.

The inventors apply a magnetic field generated from one magnetic field generating means to a part of the composite magnetic wire with respect to the composite magnetic wire capable of causing a large Barkhausen jump, and thereby the magnetic field strength or the direction of the magnetic field of the magnetic field generating means. It has been clarified in Japanese Patent Application No. 2005-177296 that an electric pulse can be generated by changing.

  The principle is that when a detection coil is wound around a composite magnetic wire that can cause a large Barkhausen jump, one of the magnetic poles of a permanent magnet is brought close to the composite magnetic wire, and a part of the side of the composite magnetic wire is excited, The magnetic domain of the soft layer reverses and expands from the excited part. It is considered that the electric induction by the expansion of the magnetic domain is output as an electric pulse by the detection coil installed in the vicinity of the composite magnetic wire. The present invention is a rotational motion detection device in which a single permanent magnet is arranged so as to circularly move on a plane parallel to the center line of the magnetic wire by applying this principle.

In the conventional example, as shown in FIGS. 11 and 12, with respect to the installation location and direction of the composite magnetic wire, the magnetic wire is installed on the outer peripheral side surface of the disk on which the magnet is mounted or in the vicinity of the outer peripheral side surface. In this method, the center line of the wire is set perpendicular to the rotation axis of the disk and parallel to the tangential direction of the rotation of the permanent magnet. If the center line of the magnetic wire can be arranged in the diameter direction of the disk with respect to the direction of the magnetic wire, the portion where the magnetic wire is installed further outside the outer periphery of the disk can be reduced, and the rotational motion detection device It becomes possible to make the whole volume smaller.

  Further, the magnetic wire is sufficiently longer than the detection coil, and the permanent magnet passes through the vicinity of the magnetic wire at a position away from the detection coil, so that a rotary motion detection device with a further reduced volume is possible.

With regard to the position of the detection coil wound around the magnetic wire, the detection coil is wound around one side of the magnetic wire, and the portion close to the permanent magnet is made only of the magnetic wire, so that the side of the magnetic wire It can be set as the structure where a permanent magnet comes closer. By adopting this arrangement, at least the volume occupied by the detection coil can be reduced as compared with an installation method in which a permanent magnet is brought close to a portion around which the detection coil is wound.

The above configuration is such that the magnetic wire has a portion where the detection coil is not wound, and the composite magnetic wire is perpendicular to the center line of the rotational motion of the permanent magnet in a plane parallel to the rotational surface of the disk. The permanent magnet is moved closer to and away from the portion of the composite magnetic wire where the detection coil is not wound. According to the previous operation principle of the Die Barkhausen jump, it is possible to generate an electric pulse corresponding to the movement of the permanent magnet from a detection coil installed in a portion where the magnet of the composite magnetic wire is not close. With this configuration, it becomes possible to generate an electric pulse by placing a magnetic wire with a smaller permanent magnet, and it is possible to configure a rotation detection device with a smaller volume and a simple structure, and with a higher resolution. High rotational motion detection device.

According to the present invention, it is possible to configure a rotary motion detection device that generates an electric pulse with a simple configuration by adopting a configuration in which a permanent magnet mounted on a disk passes through the vicinity of a magnetic wire.

In addition, according to the present invention, an electric pulse can be generated if a detection coil is installed on a part of the magnetic wire, and the detection coil is wound around the part where the magnetic field is applied to the magnetic wire. There is no need. Therefore, the portion of the magnetic wire facing the permanent magnet is a portion where there is no detection coil around the magnetic wire, and a very thin magnetically sensitive portion can be formed. Install a magnetic wire in a plane parallel to the rotating disk, extend the magnetic wire to the outside of the disk, and install a detection coil in the part where the magnetic wire extends to the outside of the disk, so that the volume can be reduced. A rotational motion detecting device having a simple structure is possible.

In addition, according to the present invention, a plurality of permanent magnets can be mounted on a single disk, and each permanent magnet can generate an electric pulse train by being close to and separated from a thin portion of only a magnetic wire, It is possible to output an electric pulse train corresponding to the arrangement of the magnets.

Conventionally, a permanent magnet that applies a magnetic field to a thin magnetic wire needs to have a sufficient magnetic field strength to give the magnetic wire a magnetic field change that causes a large Barkhausen jump, but the size of the permanent magnet is not relevant . As a result, a permanent magnet can be made smaller than before and a rotation detection device having a higher resolution than before can be configured.

The rotational motion detection device according to the present invention can expand the range of use of an electrical pulse generator using a composite magnetic wire, particularly in an application field for obtaining an electrical pulse accompanying the motion of a rotating body.

The present invention adopts a configuration in which a magnetic field is applied to a part of the composite magnetic wire by locally approaching one permanent magnet to a part of the composite magnetic wire. By adopting this configuration, it is possible to realize a structure of a rotational motion detection device that does not require a large volume for mounting. A description will be given below in accordance with examples.

In the following examples, the direction of the rotation center line of the rotating body will be described as the X direction, the center line direction of the composite magnetic wire as the Y direction, and the direction perpendicular to the X direction and the Y direction will be described as the Z direction.

Example 1 is shown in FIG. 1 includes a composite magnetic wire 1, a detection coil 2 wound around the composite magnetic wire 1, and a magnetic field generating means for generating a magnetic field capable of magnetizing a part of the composite magnetic wire 1. The cuboid permanent magnet 3 is provided. The permanent magnet 3 has an appropriate distance from the center line position in the length direction of the composite magnetic wire 1, does not contact the composite magnetic wire 1, and magnetizes a part of the composite magnetic wire 1 from the side surface of the composite magnetic wire 1. So close to each other. In the state of FIG. 1, the permanent magnet 3 is magnetized in a direction (Z direction) orthogonal to the center line (Y direction) of the composite magnetic wire 1. In the example of FIG. 1, the disk 4 is an arrow in FIG. 1. As the N pole approaches the composite magnetic wire 1 as it rotates in the direction, the S pole approaches the wire.

In FIG. 1, when the permanent magnet 3 moves in the Z direction indicated by the arrow, the two upper and lower end portions in the Z direction of the permanent magnet 3 and one composite of each of the two composite magnetic wires closest to each other are electrically connected. A pulse is generated. Therefore, positive and negative electric pulses can be generated at intervals corresponding to the moving speed of the magnet 3 and the width of the magnet 3.

Specifically, an operation example of the rotational motion detection device having such a configuration will be described. In FIG. 1, a bicalloy wire having a diameter of 250 μm and a length of 22 mm is used as the composite magnetic wire 1, and a detection coil 2 of 3000 turns is wound in the range of 2 mm to 12 mm from one end. The permanent magnet 3 has a thickness of 1 mm in the X direction, a width of 3 mm in the Y direction, and a size of 2 mm in the Z direction, and is magnetized to a magnetic field strength of 350 mT in the Z direction.

The permanent magnet 3 is arranged so as to be able to rotate and move 1 mm away in the XY direction so as not to contact the composite magnetic wire 1, and the center position of the permanent magnet 3 when moving in the Y direction is the rotation center of the composite magnetic wire 1. It moves in the YZ direction so as to coincide with the position 5 mm from the end on the center side. When the permanent magnet moves relative to the composite magnetic wire, an electric pulse is generated in the detection coil wound around the composite magnetic wire 1. When the permanent magnet 3 moves in the Z direction according to the first embodiment, the upper and lower ends in the Z direction of the permanent magnet 3 are at positions where the composite magnetic wire 1 is closest to each other, and one electrical pulse is provided for each positive and negative. Will occur. That is, one positive and one negative pulse is generated that does not depend on the moving speed of the permanent magnet 3. FIG. 3 illustrates the electric pulse output of the first embodiment. In the rotational motion detector having the structure as in the first embodiment, the magnitudes of the two positive and negative electric pulses are different.

In the first embodiment, when the directions of the N pole and the S pole are reversed by the magnetization of the permanent magnet 3, the electrical pulse generated in the detection coil is an electrical pulse with the polarity reversed, and the output obtained by inverting FIG. The pulse is shown in FIG.

As shown in Example 1, according to the present invention, a structure in which only a thin portion of only the composite magnetic wire close to the disk is close to the permanent magnet is possible, and a large volume is required for installing the composite magnetic wire and the detection coil. do not need. Therefore, it is not necessary to increase the volume of the rotational motion detection device on which this is mounted. A rotary motion detection device that can obtain a pulse output without depending on the rotation speed with no power supply can be realized without requiring a large volume.

FIG. 2 schematically shows the second embodiment. The basic structure of the rotary motion detection device of FIG. 2 is the same as that of FIG. 1, and each element constituting the electric pulse generator can be described as the same as that of FIG.

In the second embodiment, the permanent magnets 3 and 33 are mounted on the disk 4 and the disk 44. The disk 4 and the disk 44 rotate and share a rotational movement center line axis orthogonal to the center line of the composite magnetic wire 1. The central axis direction of the rotary motion is the X direction, and the central axis direction of the composite magnetic wire is Y. The permanent magnet 3 and the permanent magnet 33 are magnetized in a direction (Z direction) orthogonal to the center line (Y direction) of the composite magnetic wire 1, and in the example of FIG. 2, the rotating disks 4 and 44 are shown in FIG. With the rotation in the direction of the arrow, the composite magnetic wire 1 is arranged so that the N pole approaches and then the S pole approaches. As the disk 44 rotates in the direction of the arrow in the figure, the N pole comes close to the composite magnetic wire 1 after the S pole comes close to it.

The operation of the electric pulse generator having such a configuration will be described. In FIG. 2, when the permanent magnet 3 rotates with respect to the composite magnetic wire 1 in the direction of arrow Z in the figure, an electric pulse signal is generated in the detection coil 2 wound around the composite magnetic wire 1. When the permanent magnet 3 moves in the Z direction in the second embodiment, one electrical pulse is provided at each of the positive and negative electrical pulses at a position where the upper end and the lower end of the permanent magnet 3 are closest to a part of the end of the composite magnetic wire 1. Will occur. Therefore, electric pulses can be generated at intervals corresponding to the moving speed of the permanent magnet 3 and the width of the permanent magnet 3.

Further, when the permanent magnet 33 rotates with respect to the composite magnetic wire 1 in the direction of arrow Z in the figure, an electric pulse signal is generated in the detection coil 2 wound around the composite magnetic wire 1. The electrical pulse is generated at the position where the upper end and the lower end of the permanent magnet 33 are closest to the recombination magnetic wire 1. Therefore, electric pulses can be generated at intervals corresponding to the moving speed of the permanent magnet 33 and the width of the permanent magnet 33. Therefore, if the permanent magnet 3 and the permanent magnet 33 are set to different sizes, electric pulses can be generated at time intervals corresponding to the rotational movement of the respective magnets.

Specifically, an operation example of the electric pulse generator having such a configuration will be described. The size and performance of each element are the same as in Example 1, but the permanent magnet 3 has a thickness of 1 mm in the X direction, a width of 3 mm in the Y direction, and a size of 2 mm in the Z direction, and a magnetic field strength of 350 mT in the Z direction. In contrast, the permanent magnet 33 has a thickness of 1 mm in the X direction, a width of 3 mm in the Y direction, and a size of 3 mm in the Z direction, and is magnetized to a magnetic field strength of 350 mT in the Z direction.

The permanent magnet 3 is mounted on a rotating disk 4 that rotates in a state of being 1 mm away in the X direction so as not to contact the composite magnetic wire 1. The permanent magnet 3 is in the direction of the arrow shown in FIG. It moves perpendicular to the direction of the center line of the wire 1 (Y direction). In the second embodiment, a permanent magnet 33 is further mounted on a disk 44 that rotates with the rotating disk 4 and the rotation center axis in common. The disk 4 and the disk 44 rotate independently of each other. In the second embodiment, two positive and negative electric pulses corresponding to the permanent magnet 3 are generated along with the rotation of the disk 4, and two positive and negative electric pulses corresponding to the permanent magnet 33 are generated along with the rotation of the disk 44. The interval between the positive and negative electric pulses corresponding to the permanent magnet 33 differs depending on the lengths of the permanent magnet 3 and the permanent magnet 33 in the Z direction.

In the second embodiment, when the direction of one of the N pole and the S pole is reversed by the magnetization of the permanent magnet 3 and the permanent magnet 33, the polarity of the electric pulse generated in the detection coil is reversed by the permanent magnet. Since a pulse signal is obtained, the output pulse shown in FIG. 5 is obtained.

When the disk 4 on which the permanent magnet 3 is mounted and the disk 44 on which the permanent magnet 33 is mounted independently rotate, when a pulse output is obtained by the conventional example, a plurality of disks corresponding to each disk are obtained. Whereas a magnetic wire element is required, by adopting the configuration of the second embodiment, the magnetic wire element can be configured with a pair of magnetic wires and a detection coil to be a simple configuration. Also, the installation space is a structure in which the composite magnetic wire is installed in a narrow space between the two disks, so that the installation can be performed with a smaller volume than the conventional example.

The rotational motion detection device of the present invention can be used for detection of rotational speed or counting of the number of rotations because a non-powered electric pulse output can be obtained with a simple configuration.

  Conventionally, a rotation detection device using a composite magnetic wire that has not been sufficiently put into practical use due to its complicated configuration to give fluctuations in magnetic bias can be realized with a simple configuration, A pulse output speedometer, speed counter, and various encoders can be easily realized.

It is a block diagram which shows the 1st Example of the rotational motion detection apparatus of this invention. It is a block diagram which shows the 2nd Example of the rotational motion detection apparatus of this invention. It is a figure which shows the output of the 1st Example of the rotational motion detection apparatus of this invention. It is a figure which shows the output of the 2nd Example of the rotational motion detection apparatus of this invention. It is a 2nd figure which shows the output of the 2nd Example of the rotational motion detection apparatus of this invention. It is a block diagram which shows the prior art example 1 of a rotational motion detection apparatus. It is a block diagram which shows the prior art example 2 of a rotational motion detection apparatus.

Explanation of symbols

1 Composite magnetic wire
2 Detection coil
3 Permanent magnet
4 Disc 10 Electric pulse generator 33 Permanent magnet 44 Disc

Claims (2)

A rotational motion detection device having at least one permanent magnet as a magnetic field generating source arranged by winding a detection coil around a magnetic wire capable of causing a large Barkhausen jump to induce a large Barkhausen jump, Rotating motion detecting device characterized by relatively moving on a plane parallel to the center line of the magnetic wire and in the vicinity of one side surface of the magnetic wire. 2. The rotational motion detection device according to claim 1, wherein the magnetic wire is sufficiently longer than the detection coil, and the permanent magnet passes near the magnetic wire at a position away from the detection coil.