JPS6234084B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to vibration or shock detectors. More specifically, the present invention relates to a magnetostrictive detector used to detect abnormal vibrations or shocks in equipment in various fields, such as knocking in automobiles and abnormal rotational vibrations during dehydration of washing machines.

Conventionally, as a magnetostrictive pressure sensor that utilizes the magnetostrictive effect of a ferromagnetic material, a sensor in which two coils, one for excitation and one for output, are wound around a laminated silicon steel plate is often used. However, such a sensor has drawbacks such as difficulty in making it small and compact and requires an external power source, and is therefore unsuitable for use as a vibration or shock detector as described above. Furthermore, detection sensitivity is low. Furthermore, some equipment is required to operate under poor conditions, but their corrosion resistance does not allow them to withstand such use.

In addition, winding a coil around a ferromagnetic round bar,
There are those that are magnetized in the axial direction with alternating current and detect changes in magnetization in the circumferential direction with a separate detection coil, and those that are magnetized in the circumferential direction with current passed in the axial direction and detect changes in magnetization in the axial direction. Devices that use coils for detection are also known, but all of these require an external power source and have various other drawbacks, making them unsuitable for use as vibration or shock detectors as described above.

Purpose of the Invention The present invention was made in view of the above circumstances, and does not require an external power source, has a small, compact, and robust structure, and has high detection sensitivity. The main purpose of the present invention is to provide a magnetostrictive vibration or shock detector which has features such as being able to operate accurately over a long period of time even under poor conditions.

The inventors of the present invention have repeatedly conducted intensive studies regarding this purpose, and have found that when only an output coil is wound around a so-called amorphous magnetic alloy thin plate that has been subjected to a predetermined treatment, and when vibrations and shocks are applied to the thin plate, The magnetization changes due to the strain generated in the coil, and this changed magnetization generates an electromotive force at both ends of the coil, making it possible to effectively detect vibrations etc. without an external power source.
It was discovered that such detection can be effectively carried out only when a so-called amorphous magnetic alloy thin plate is subjected to a prescribed treatment to precipitate microcrystals in the amorphous state. Based on this knowledge, the present invention was made. It is ivy.

In other words, the present invention includes a thin plate of a magnetic alloy in which microcrystals are mixed in an amorphous state, and a support that supports the thin plate.Only an output coil is wound around the thin plate, and vibration The vibration or shock detector is characterized in that it is configured to output an electromotive force that changes based on a change in magnetization of the thin plate to both ends of the coil due to strain generated in the thin plate when an impact is applied.

As mentioned above, when a so-called amorphous magnetic alloy thin plate is not subjected to a prescribed treatment and a thin plate exhibiting an almost completely amorphous state is used, even if the detector is constructed as in the present invention, it is not sufficient. I can't get any output,
Vibration or impact detection cannot be performed effectively.

Furthermore, when detecting vibrations or shocks and outputting them as electrical signals, strain gauges and piezoelectric elements have traditionally been used, but these have the disadvantage of requiring an external power source. Until now, a detector that does not require a power source, is small, compact, and has a robust structure has not been realized.

Specific Configuration of the Invention Hereinafter, a specific configuration of the present invention will be described in detail according to the embodiment shown in FIG.

The vibration or shock detector of the present invention comprises a thin plate 1, as shown in FIG.

The magnetic alloy thin plate 1 used is amorphous with microcrystals mixed therein. That is, using a thin plate
When line diffraction is performed and a diffraction X-ray spectrum is taken, a pattern intermediate between amorphous and crystalline is given with a peak above the halo. Moreover, according to the X-ray diffraction photograph, a Debye-Sierer ring with a predetermined ring diameter and ring width, which is intermediate between amorphous and crystalline, is also observed. From the ring diameter and ring width of the Debye-Sierer ring, it is considered that the crystalline substance is uniformly precipitated and mixed in the amorphous substance in a microcrystalline state.

In this case, the microcrystals precipitated in the thin plate generally have the following area ratio between the halo and the peak:
It is present in about 5 to 70% of the amorphous state. Furthermore, it is thought that the microcrystals are usually precipitated with an average grain size of approximately several tens to several hundred angstroms, based on the ring diameter and ring width of the Debye-Sierer ring.

The composition of such a magnetic alloy thin plate in which microcrystals are mixed in the amorphous state is usually any of the known compositions of so-called amorphous magnetic alloy thin plates consisting of iron group elements and vitrified elements. good.

That is, it may contain approximately 10 to 35 at% of the vitrifying element, and the remainder substantially consist of one to three iron group elements such as Fe, Co, and Ni. in this case,
The vitrification element is preferably one to four of Si, B, P, and C. In addition, the thin plate may contain one or more of other transition metal elements such as Mo, W, Nb, and Cr within a range of 10% or less of the total amount of iron group elements.
It may contain more than one species.

In this case, if a thin plate with a larger saturation magnetostriction is used, the detection accuracy will be improved and more favorable results will be obtained. From this point of view, thin plates, in particular,
It is preferable to have a composition represented by the following formula in which Fe is an essential component as an iron group element.

Formula (Fe _k Co _l Ni _{n To} ) _x X _y M _z In the above formula, T represents one or more of Mo, W, Nb and Cr, and X represents one to one of Si, B, P and C. 4
M represents Ta, V, Mn, Cu, Ti, Zn, Al, Ge, which may be contained as trace components.
Represents one or more of In, Sn, Sb, Ag, Au, Pd, etc. Also, x+y+z=100at%, of which y is 10 to 30at% and z is a small amount, for example 0 to 4at%.
%. Furthermore, k+l+m+n=100%,
Among these, k never takes 0, and l ranges from 0 to
80 at%, more preferably 0 to 20 at%, m is 0 to
50 at%, n is 0 to 10 at%.

In order to obtain a thin plate of such a magnetic alloy, a thin plate that is almost completely amorphous is obtained by a conventional method using a known high-speed quenching method, and then this is heat-treated at a temperature near the crystallization temperature (especially , rapid heating, and rapid cooling) to precipitate microcrystals. Alternatively, heat treatment may be performed while applying a magnetic field to an almost completely amorphous thin plate. In this case, the processing conditions for making the microcrystals coexist in the amorphous state vary depending on the composition of the thin plate, but these can be easily determined through experiments.

As described above, the magnetic alloy thin plate used in the present invention is composed of a mixture of precipitated microcrystals in an amorphous state, but it is almost completely amorphous immediately after being manufactured by the high-speed quenching method. In the case of a thin plate that has undergone excessive heat treatment and has become almost completely crystallized, the output electromotive force will be low and a satisfactory output signal will be obtained even if the detector is configured according to the present invention as described in detail later. can't get it.

It is not always clear why a sufficient output signal is obtained only when microcrystals are formed, but this is because the precipitation of microcrystals causes internal strain inside the thin plate, causing the thin plate to move in a given direction. This is thought to be because the axis of easy magnetization is induced and the sensitivity to stress is significantly improved.

Thin sheets of such magnetic alloys generally have a thickness of 10 to
The thickness should be approximately 100 μm. Further, the dimensions of the flat plate may be approximately 1 mm x 10 mm or more.

Incidentally, in order to further increase the corrosion resistance of such a thin plate of magnetic alloy, a coating of nickel, chromium, or the like may be formed on the surface thereof. Further, the thin plate used may be subjected to a treatment such as applying tension in advance.

Although a plurality of such magnetic alloy thin plates may be used in a stacked manner, it is usually sufficient to use only one of them.

Thin plate 1 of magnetic alloy as described above in detail
is supported by a predetermined support 2. thin plate 1
can be supported by the support body 2 in various shapes. However, normally, as shown in FIG. 1, it is sufficient to support the thin plate 1 in a flat plate shape so as to maintain the flat plate shape planarly.

The support 2 is not particularly limited as long as it can support and fix the thin plate 1 in, for example, a substantially flat plate shape and is made of a rigid body with a certain degree of elasticity. For this reason,
Usually, the support body 2 may be formed from metal. The structure thereof can be various. .

In the example shown in FIG. 1, the support body 2 is constructed from two U-shaped metal frames, and the thin plate 1 is sandwiched and bonded within the frames. As shown in the figure, the thin plate 1 is normally supported and fixed at both ends in its longitudinal direction by a support 2 with a certain amount of tensile force, so that its flat plate shape is maintained.

On the other hand, an output coil 3 is wound around the thin plate 1 supported in this manner.

In this case, the present invention does not use an excitation coil that is separately connected to an external power source. The output coil 3 is usually wound in a predetermined number of turns in the width direction of the thin plate.

In such a configuration, vibrations or shocks are directly or indirectly transmitted to the thin plate 1.
In this case, the output obtained is larger, as shown in the figure, the force P associated with vibration etc. is applied in the longitudinal direction of the surface of the thin plate 1, and when the vibration etc. are applied, strain is generated in the longitudinal direction. It is preferable that the configuration is as follows. This is because the above-described treatment generally induces an axis of easy magnetization in the width direction of the thin plate, increasing stress sensitivity to stress in the longitudinal direction. In the illustrated example, vibrations, etc. are directly transmitted to a flat area of the support 2 that grips and fixes one end of the thin plate 1. Applying vibration directly to the thin plate end face of the exit part, or via a separately installed diaphragm,
Vibrations and the like can also be transmitted to the support 2 and the thin plate 1.

Specific Effects of the Invention Detection can be performed as follows using the vibration or impact detector of the present invention having such a configuration.

That is, when a force P associated with vibration or impact is applied directly or indirectly, strain occurs in the thin plate 1. In a preferred embodiment, magnetization occurs in the longitudinal direction due to strain occurring in the longitudinal direction of the thin plate, and an electromotive force e is generated between the terminals of the coil 3 in response to changes in magnetization that change due to vibrations, etc. An output waveform of the electromotive force e that changes as follows is obtained.
Vibration and the like will be detected from this output waveform.

Then, this output waveform is input to a comparator, or in some cases, the analog value is read, and appropriate electrical processing is performed to detect knocking in a car or washing machine. Dehydration abnormal rotation detection will be performed.

According to the present invention, a vibration or shock detector that does not require an external power source is realized.

In addition, the structure is such that only the output coil 3 is wound around a thin plate 1 made of a predetermined magnetic alloy and housed within the rigid support 2 without using an external power source, resulting in a small, compact and robust structure. can do.

Furthermore, since the thin plate is made of a magnetic alloy in which microcrystals are mixed in an amorphous state, detection sensitivity is extremely high, and detection can be performed with good accuracy.
In this case, as will become clear from the experimental examples described later, when a substantially completely amorphous or crystalline magnetic alloy is used as the thin plate, a satisfactory output signal cannot be obtained. If the structure is such that vibration or impact is applied in the longitudinal direction of the thin plate, the detection sensitivity will be extremely high.

In addition, such thin plates, like the amorphous magnetic alloy before treatment, have high corrosion resistance, allowing for detectors that operate accurately even under adverse conditions. In particular, if a corrosion-resistant coating is formed on the surface of the thin plate, this effect will be even higher.

The present inventors conducted various experiments to confirm the effects of the present invention. An example is shown below.

Experimental example 1 A long thin plate with a thickness of 40 μm having a composition of Fe ₈₀ B ₂₀ was obtained by the high-speed quenching method, and this was made into a sheet with a width of 1 mm and a length of 30 μm.
I extracted it to mm. This thin plate is completely amorphous according to X-ray diffraction, and its crystallization temperature is 390°C.

Next, for each of these four thin plates (A to D), one
(A) was not subjected to any heat treatment, and the other three (B~
D) are 250℃ (B), 355℃ (C) and 390℃ (D) respectively.
After heat treatment for 1 hour, the mixture was air cooled to room temperature.

As a result of X-ray diffraction, the thin plate obtained in this way was
A and B were completely amorphous, and D was completely crystalline, whereas C was amorphous with microcrystals mixed in, and the average diameter of the microcrystals was estimated to be 50 to 200 Å. Ta.

For the four thin plates A to D obtained in this way,
As shown in Figure 1, this is 30mm x 30mm x
Both ends in the longitudinal direction were adhesively fixed in a flat plate shape within a 20 mm aluminum support 2 using instant adhesive Aron α (trade name).

On the other hand, an output coil 3 was wound around each thin plate 1 with 8000 turns.

In this way, using the detector configured for each of the thin plates A to D, a 20 mg minute piece of iron was dropped onto the support 2 from a height of 1 cm or more, and the electromotive force e at both ends of the coil 3 was measured. , when thin plates A, B, and D were used, a satisfactory output voltage could not be obtained, whereas when thin plate C was used, the second
As shown in the figure, 1cm(a), 2cm(b), 3cm(c),
As the falling height was changed to 4 cm (d), it was possible to obtain output voltage waveforms of electromotive force e corresponding to the falling height.

In addition, the thin plate A having the above composition immediately after high-speed quenching was heated at various heating temperatures Tan for 1 hour, then air cooled to room temperature, and the thin plate after each heat treatment was heated at 60Hz,
Sine wave excitation was performed at 0.5 Oe. The maximum magnetic permeability μmo of each thin plate when excited, and the change in maximum magnetic permeability Δ when a tension of 5 Kg/mm ² is applied in the longitudinal direction of the thin plate and excited.
μm=μm (σ=5Kg/mm ² )−μmo was measured. In this case, the BH
Measured from the loop. Heating temperature Tan and Δμm/
The relationship with μmo is shown in Figure 3.

From the results shown in Figure 3, an abnormally high Δμm/μmo is shown at a heating temperature Tan of 340 to 360°C, where microcrystals are mixed in the amorphous state, and this results in a satisfactory output signal as described above. On the other hand, at other heating temperatures Tan, which are almost completely amorphous or almost completely crystalline, Δμm/μ
It can be seen that mo is extremely small, which makes it impossible to obtain a satisfactory output signal.

Experimental Example 2 355 for Fe ₈₀ B ₂₀ thin plate in Experimental Example 1
℃ for 1 hour and air cooling, the surface was plated with Ni and a detector was configured in exactly the same manner as in Experimental Example 1, and it was possible to obtain an output signal exactly the same as in Experimental Example 1. In addition, extremely good corrosion resistance was exhibited.

Experimental Example 3 A long thin plate with a _thickness of ₄₀ μm and having a composition of Fe ₈₁ (Si _0.1 B _0.9 ) ₁₉ was obtained by a high-speed quenching method. This thin plate is completely amorphous as a result of X-ray diffraction, and its crystallization temperature is 460°C.

Of these three long thin plates, one (E) was left as is without any heat treatment, and the other two (F,
G) are 430℃, 20 minutes (F) and 450℃, respectively.
After heating for 20 minutes (G), it was air cooled to room temperature. Next, each of these pieces was cut out to a width of 1 mm and a length of 30 mm. In this case, when X-ray diffraction was performed on thin plates F and G,
It was confirmed that G was completely crystalline, and F was amorphous with microcrystals mixed therein.

When we fabricated detectors for each of these thin plates E to G in the same manner as in Experimental Example 1 and conducted the same tests, we found that when thin plates E and G were used, a satisfactory output signal could not be obtained. On the other hand, when thin plate F containing microcrystals was used, an output waveform equivalent to that of Experimental Example 1 could be obtained.

Note that when the surface of this thin plate F was chrome plated, the same output signal could be obtained.

In addition, for the thin plate E after the above-mentioned high-speed quenching, the heating temperature
Heating and air cooling to room temperature were performed by varying the Tan and heating time, and in each case, Δμm/μmo [Δμm=μm [σ
=5Kg/mm ² )-μmo] was measured. In Figure 4,
The horizontal axis represents the heating time t, the vertical axis represents the heating temperature Tan, and the heating temperature Tan at which Δμm/μmo becomes maximum for a constant heating time t is indicated by a black circle. in this case,
Under the conditions indicated by black circles, microcrystals were mixed in the amorphous state. In addition, in the shaded area in FIG. 4, the thin plate is almost completely crystallized, and Δμ
m/μmo was almost zero.

Experimental Example 4 In the same manner as in Experimental Example 1, a completely amorphous thin plate having a composition of Fe ₇₈ Mo ₂ B ₂₀ and a thickness of 40 μm (crystallization temperature 420° C.) was obtained.

This thin plate was heated at 410°C for 20 minutes and then air cooled to room temperature. At this time, it was confirmed by X-ray diffraction that microcrystals were mixed in the amorphous material.

Next, when a detector was constructed in the same manner as in Experimental Example 1 using this thin plate, an output signal equivalent to that in Experimental Example 1 could be obtained.

Note that a satisfactory output voltage could not be obtained with a thin plate that was not subjected to any heat treatment immediately after high-speed quenching.

Further, when the tension σ was variously changed for the thin plate after the above-mentioned heat treatment and Δμ=μm−μmo was measured, a change in Δμm/μmo as shown in FIG. 5 was obtained.

Experimental Example 5 In Experimental Example 1, the thin plate (Fe ₄₀ Ni ₄₀ ) ₈₀ P ₁₄ B ₁₆
Instead, when we used one that had been heat-treated at 300°C for 60 minutes and then air-cooled to room temperature, we obtained an output signal that was almost the same as in the experimental example.

Experimental Example 6 In Experimental Example 1, the thin plate was (Fe ₀ . ₉₅ Co ₀ . ₀₅ ) ₈₀
( _{B 0.9} Si _0.1 ) ₂₀ and _{( Fe 0.85 Ni 0.15 ) 80} ( _{B 0.9}
Instead of Si _0.1 ) _{20 ,} we heated each of them at 400℃ for 30 minutes while applying a magnetic field of 1000 Oe in the width direction of the thin plate, and then air-cooled them to room temperature, and the output was almost the same as in Experimental Example 1. Got a signal.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention.
FIG. 2 is a diagram for explaining the effects of the present invention, and a to d are the electromotive force e (0.1V/1
FIG. 2 is a diagram showing a change in time t (20 μsec/1 cm) in cm). Figure 3 shows the ^maximum magnetic permeability change Δμm/μmo [Δμm=μm
(σ=5Kg/mm ² )−μmo(σ=0)] and heating temperature Tan. FIG. 4 is a diagram showing the heating time Tan indicating the maximum value of Δμm/μmo when an amorphous magnetic alloy thin plate is subjected to heat treatment for a heating time t. FIG. 5 is a diagram showing the relationship between Δμm/μmo and tension σ of a thin plate. 1... Thin plate of magnetic alloy, 2... Support, 3...
Coil for output.

Claims (1)

[Claims] 1. A thin plate of a magnetic alloy in which microcrystals are mixed in an amorphous state, and a support that supports the thin plate, and only an output coil is wound around the thin plate. ,
A vibration or shock detector characterized in that the vibration or shock detector is configured to output an electromotive force that changes based on a change in the magnetization of the thin plate to both ends of the coil due to the strain generated in the thin plate when vibration or shock is applied. 2. The vibration or impact detector according to claim 1, which comprises a thin plate supported in a flat plate shape by a support. 3. The vibration or shock recited in claim 2, wherein the thin plate is supported in a flat plate shape by a support at both ends in the longitudinal direction of the thin plate, and vibration or impact is applied in the longitudinal direction of the thin plate. Shock detector. 4. A thin plate of magnetic alloy contains 10 to 35 at% of vitrifying elements, with the balance substantially consisting of 1 to 35 at% of Fe, Co, and Ni.
The vibration or impact detector according to any one of claims 1 to 3, comprising three types. 5. The vibration or impact detector according to any one of claims 1 to 4, wherein a corrosion-resistant coating is formed on the surface of the thin plate.