JPS648929B2 - - 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 for various mechanical devices, such as automobile ignition systems, tachometers, and proximity switches.

Recently, it has been considered to equip automobiles with microcomputers for automatic control, but automatic control requires a large number of synchronization signals for each revolution of the engine, and each signal is connected to the engine. It is desirable to always be able to reliably obtain a constant size regardless of speed.

As a means of generating such pulses,
Conventionally, for example, there has been known a device called "Self-Nucleating Magnetic Wire" shown in US Pat. . Ferromagnetic wires are used for these, but when the external magnetic field that has magnetized the entire ferromagnetic wire in the axial direction is cut off, only the direction of magnetization in the wire core changes to the magnetic field line in the outer core. is autonomously reversed in the direction of forming a return magnetic path. Although attempts are made to generate pulses based on changes in the magnetic flux at the time of reversal, they have the drawbacks 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 has uniaxial magnetic anisotropy in the line axis direction, has a portion near the core of the wire that is magnetized in the positive direction and has a large coercive force, and has an external The detection coil is wound around a magnetically sensitive element made of a composite ferromagnetic material having a portion with a low coercive force that can be magnetized in either the positive or negative direction depending on the direction of action of the magnetic field. A relatively strong first magnet that acts in the positive direction as the external magnetic field and a weak second magnet that acts in the negative direction are respectively fixed on both sides of the magnetic sensing element, and when brought close to the first magnet, the It is characterized by being combined with a magnetic movable body that forms a magnetic path where lines of magnetic force are concentrated and reduces the magnetization effect on the magnetically sensitive element.

First, an overview of the magnetically sensitive element used in the device of 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 relatively large coercive force near the wire core. It becomes a composite ferromagnetic material, that is, a magnetically sensitive element, which has a portion with a small coercive force in the outer peripheral portion adjacent to this.

First, the entirety of such a magnetically sensitive element is oriented and magnetized in the positive direction (for example, rightward with respect to the line axis) by a sufficiently large first magnetic field, and then the first magnetic field is interrupted. 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). In this state, when a third magnetic field in the same direction as the first magnetic field is applied again, the portion with a small coercive force is aided by the action of the positive orientation magnetism of the portion with a large coercive force, and rapidly and suddenly. It is reversed in the forward direction (right direction). Therefore, in response to the magnetization change at this time, a steep and large pulse electromotive force is induced in the detection coil placed nearby.

Because of this principle of inducing pulsed electromotive force, as long as a weak second magnetic field is linked with a strong third magnetic field, a pulsed electromotive force of a magnitude greater than a certain value can always be generated. can. This is because the magnitude of the electromotive force is controlled based on the magnetic flux change due to a unique magnetic reversal phenomenon caused by the magnetic interaction between adjacent magnetic layers inside the composite magnetic material. This is a unique induced pulse that is completely different from conventional induced electromotive force that depends on the rate of change in flux linkage.

Note that since the first magnetic field and the third magnetic field may be the same, in reality, the second magnetic field in the negative direction and the first magnetic field in the positive direction are alternately applied to the magnetically sensitive element. It is possible to induce sequential pulses by simply

Next, embodiments of the present invention will be described with reference to the drawings.

In FIGS. 1 and 2, 1 is the aforementioned magnetically sensitive element, and 2 is a detection coil wound around (or placed near) it. Further, 3 is a sufficiently strong first magnet to magnetize the entire magnetically sensitive element 1 in the positive direction, and 4 is a weak first magnet to magnetize only a portion of the magnetically sensitive element 1 with a relatively small coercive force in the negative direction. 2
Both are held in place by magnets. The magnet referred to here generally refers to a permanent magnet, but may also be an electromagnet.

A magnetic movable body 5 that intermittently reduces the magnetization effect of the first magnet 3 is combined with these fixed sides.

As this magnetic movable body 5, for example, a rotor made of a magnetic material as illustrated in FIGS. 3 and 4 is used. The magnetic movable body 5 shown in FIG.
It is a disk of magnetic material with a large number of hollow parts 7 (hereinafter, slit parts where magnetic material is partially omitted are referred to as hollow parts). It is a windmill-shaped rotor that is provided with convex bodies 8 radially.

Next, to describe the operation of this device, when the magnetic movable body 5 is brought close to the relatively strong first magnet 3 for the magnetically sensitive element 1 whose entirety has been magnetized in the positive direction, the magnetic body part It becomes a magnetic path that concentrates the lines of magnetic force, and therefore reduces the magnetizing effect on the magnetically sensitive element 1. When the action of the first magnet 3 is cut off in this way, only the relatively weak second magnet 4 acts, and only the portion with a relatively small coercive force is magnetized in the negative direction.

Next, when the magnetic field lines of the first magnet 3 that have passed through the empty space of the magnetic movable body 5 due to rotation of the rotor act on the magnetically sensitive element 1, the magnetic field of the second magnet 4 is attenuated by this magnetic field, and the magnetic field of the second magnet 4 is As described above, the magnetization direction of the portion with a small coercive force is gradually and rapidly shifted to the positive direction. Therefore, at this time, a steep pulse electromotive force is generated in the detection coil 2. Therefore, by increasing the number of hollow portions 7 or convex bodies 8, a large number of pulses can be generated for each rotation of the rotor.

In this case, even if the rotational speed of the rotor fluctuates, or even if it rotates at an extremely low speed, it is possible to always reliably generate a pulse electromotive force of a certain magnitude or higher based on the reason described in the above principle.

Incidentally, when increasing the number of hollow portions 7 and convex bodies 8, the rotor may be molded with synthetic resin or the like in order to reinforce the mechanical strength of the rotor.
Alternatively, a magnetic material may be attached to a required portion of a rotor made of a strong non-magnetic material.

Furthermore, although the rotor has been used as an example of the magnetic movable body 5 that intermittents the action of the first magnet 3, it may also be a vibrating body or a reciprocating body that moves the magnetic body close to and away from the first magnet 3. .

In any case, by intermittent action of the first magnet 3 on the magnetic sensing element 1 disposed in the magnetic field of the second magnetic field generation source 4, the effect is kept almost constant regardless of the magnitude of the intermittent speed. Since it has the feature of being able to reliably obtain a large number of pulse signals of different magnitudes, it is extremely effective for use in various automatic control systems that require a large number of synchronous signals.

[Brief explanation of drawings]

1 and 2 are diagrams showing embodiments of the present invention,
3 and 4 are plan views illustrating the movable body (rotor). 1: Magnetic sensing element, 2: Detection coil, 3: First magnet, 4: Second magnet, 5: Magnetic movable body, 6: Rotating shaft, 7: Air space, 8: Convex body.

Claims (1)

[Claims] 1. It has uniaxial magnetic anisotropy in the direction of the wire axis, has a part near the core of the wire that has a large coercive force that is magnetized in the positive direction, and has a part with a large coercive force that is magnetized in the positive direction on the outer periphery adjacent to this part, and has a positive Alternatively, for a magnetically sensitive element made of a composite ferromagnetic material having a portion with a small coercive force that can be magnetized in either the negative direction, a detection coil is wound on both sides of the magnetically sensitive element. A relatively strong first magnet that acts in the positive direction and a weak second magnet that acts in the negative direction are each fixed as an external magnetic field, and when brought close to the first magnet, a magnetic path is formed in which the lines of magnetic force are concentrated, and the above-mentioned A pulse signal generating device characterized by comprising a combination of a magnetic movable body that reduces the magnetization effect on a magnetically sensitive element.