JPS6349947Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a pulse signal generator that can be applied to various fields such as automatic control systems of various mechanical devices, such as automobile ignition systems, tachometers, and proximity switches.

Recently, it has been considered to automatically control automobiles by equipping them with microcomputers, but automatic control requires a large number of synchronizing signals as the engine rotates, and each signal is connected to the engine speed. It is desirable to always be able to reliably obtain a constant size regardless of the size.

Among such pulse generating means, one that utilizes the properties of ferromagnetic material is, for example, the
A "pulse generator" disclosed in Japanese Patent No. 13705 is known. A magnetic wire is used for this, and when the external magnetic field that is magnetized in the axial direction of the magnetic wire is cut off, only the magnetization direction of the wire core is the direction that forms the return path of the magnetic field lines in the outer core. is automatically reversed. The idea is to generate a pulse based on the change in magnetic flux during this reversal, but
There are problems in that the output is generally small and it is difficult to accurately control the timing of pulse generation.

The pulse signal generator of the present invention uses a ferromagnetic material with special properties, and its pulse generation principle is completely different from that of the above-mentioned pulse generator using a magnetic wire.

In other words, it has uniaxial magnetic anisotropy in the line axis direction,
It has a part near the core that has a large coercive force that is magnetized in the positive direction, and the outer peripheral part adjacent to this can be magnetized in either the positive or negative direction depending on the direction of action of the external magnetic field. A plurality of magnetic poles of different polarity are alternately magnetized in a circular peripheral part that rotates as the external magnetic field for a magneto-sensitive element made of a laminated composite magnetic material having a small coercive force part. The pulse signal generator is characterized by comprising a detection coil arranged so as to interlink the magnetic fields of the rotary magnets and wound around the magnetically sensitive element.

First, an overview of the magnetically sensitive element used in the present invention will be explained.

For example, a wire-shaped ferromagnetic material processed by applying external stress such as twisting has uniaxial magnetic anisotropy in the wire axis direction, and has a portion with relatively large coercive force near the wire core. This results in a composite ferromagnetic material having a portion with a small coercive force on the outer periphery adjacent to this. Alternatively, a magnetically sensitive element having the characteristics described below can be constructed by laminating magnetic layers having different coercive forces to form a composite ferromagnetic material.

The characteristics of the magnetically sensitive element are such that the entire element is first oriented and magnetized in the positive direction (for example, rightward with respect to the axis) by a sufficiently large first magnetic field, and then the first magnetic field is blocked. Next, a weak second magnetic field is applied to reverse the magnetization direction of only the portion where the coercive force is relatively small, so that the portion is magnetized in the negative direction (to the left). When the third magnetic field in the positive direction is applied again in this state, the part with the small coercive force is affected by the positive orientation magnetism of the part with the large coercive force, and quickly and gradually moves in the positive direction (rightward direction). ) is reversed. Therefore, in response to the magnetic flux change at this time, a steep and large pulse electromotive force can be induced in the detection coil placed nearby.

Because of this principle of inducing pulsed electromotive force, as long as a weak negative second magnetic field is followed by a positive third magnetic field, a pulsed electromotive force of a magnitude greater than a certain value is always generated. can do.

This is because within the composite magnetic material, changes in magnetic flux based on magnetic exchange interactions between adjacent magnetic layers govern the magnitude of the electromotive force induced in the detection coil placed nearby. This is completely different from the conventional induced electromotive force, which is thought to be induced depending on the rate of change in magnetic flux.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a rotary magnet that is interlocked with the controlled system, and is magnetized so that a plurality of north poles and south poles are distributed around the rotary magnet. Around this rotary magnet 1, a portion with a large coercive force is magnetized in advance in a positive direction (for example, rightward) via left and right yokes 2 corresponding to the spacing between a pair of N and S poles. A magnetically sensitive element 3 is arranged. In this case, the strength of the magnetic field of rotary magnet 1 is
It is relatively weak to the extent that only the magnetization direction of the portion of the magnetic sensing element 3 with a small coercive force can be shifted.

In the above configuration, when the rotary magnet 1 rotates a little so that the left yoke corresponds to the S pole and the right yoke corresponds to the N pole, only the portion of the magnetic sensing element 3 with a small coercive force moves in the negative direction ( (to the left). However, the dislocation speed at this time is small.

Next, as shown in the figure, when the left yoke corresponds to the N pole and the right yoke corresponds to the S pole, the part with the smaller coercive force rapidly reverses in the positive direction, and the detection coil 4 Induces a steep pulse signal. Therefore, as the rotary magnet 1 rotates, the magnetization direction of the portion with a small coercive force shifts alternately between positive and negative, and a pulse signal can be sequentially induced in the detection coil 4 each time the magnetization direction is reversed to the positive direction.

Also, as shown in Figure 2, the N→S direction is strong, and the S direction is strong.
→If the magnetization is made so that the N direction is weak, then N→
A steep pulse signal is obtained at the point in the S direction. As shown in FIG. 3, the rotary magnets can be provided with recesses 5 around them so that they do not emit pulse signals, or two or more rotary magnets can be stacked as shown in FIG. 4.

Alternatively, as shown in FIG. 5, if two or more magnetic sensing elements 3 are arranged for one rotary magnet 1, the number of pulse signals per rotation can be doubled, tripled, etc. can. Although the yoke 2 does not necessarily need to be used, it has the advantage that a magnetically sensitive element with a large volume can be used.

In addition, since the pulse signal generator of the present invention utilizes a magnetically sensitive element with the operating principle described above, it is independent of the rotational speed of the rotary magnet interlocked with the controlled system, that is, the rate of change of the interlinkage magnetic flux. It is characterized by extremely high reliability, since a pulse signal of approximately constant magnitude can be obtained even during extremely low speed rotation.

[Brief explanation of the drawing]

Figure 1 is a front view showing one embodiment of the present invention;
3 and 3 are front views illustrating rotary magnets, FIG. 4 is a side view when a plurality of rotary magnets are used, and FIG. 5 is a front view showing another embodiment. 1: rotary magnet, 2: yoke, 3: magnetic sensing element,
4: detection coil, 5: recess.

Claims (1)

[Scope of utility model registration request] It has uniaxial magnetic anisotropy in the direction of the wire axis, with a part near the core of the wire having a large coercive force that is magnetized in the positive direction, and an outer periphery adjacent to this having a positive or high coercive force depending on the direction of the external magnetic field. For a magnetically sensitive element composed of a laminated composite magnetic material having a portion with a small coercive force that can be magnetized in either the negative direction,
A detection coil is arranged so as to interlink the magnetic field of a rotary magnet, which is formed by alternately magnetizing a plurality of magnetic poles of different polarities in a circular peripheral part that rotates as the external magnetic field, and is wound around the magnetically sensitive element. Pulse signal generator with.