JPH10260092A - Magnetostriction memberane for magentosriction type trque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetostriction type torque sensor having a high degree of sensitivity. SOLUTION: In a magnetostriction membrane selecting method for a magentostriction membrane for a magnetostriction type torque sensor, in which a a metal shaft is coated over its outer peripheral surface with the magnetostriction membrane, a magnetostriction membrane having a composition having an absolute value of (μs*E)<1/2> ×λ, where μm is a specific magnetic permeability, E is a young's modulus, and λ is a magnetostriction constant, which is higher than 5×10<4> , is selected. Accordingly, with the use of a simple solid-state property test, or with the use of existing solid-state property data, it is possible to estimate a magentostriction membrane having a high degree of sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetically anisotropic magnetostrictive film adhered to a shaft surface, the magnetic characteristic of which is changed according to the twist of the shaft (permeability). The present invention relates to a magnetostrictive film for detecting a magnetostrictive torque sensor.

[0002]

2. Description of the Related Art Conventional methods for producing a magnetostrictive film include PVD methods such as sputtering and ion plating (for example, JP-A-60-42628 and JP-A-6-13798).
No. 1), a plating method (for example, Japanese Unexamined Patent Publication No.
No. 1) and a thermal spraying method such as a plasma spraying method (for example, JP-A-5-52678, JP-A-6-160209) has been proposed.

JP-A-6-160209 discloses a Ni-Fe film containing 40 to 80 wt% of Ni, a film containing 7 wt% or less of Al or the like in the Ni-Fe film, and a film containing 8 to 15 wt% of Al.
A wt% Fe-Al film, and a film in which Ni or the like is contained in the Fe-Al film in an amount of 5 wt% or less have been proposed. Japanese Patent Application Laid-Open No. Hei 6-137811 discloses that a 90% Ni—Fe film is used as the magnetostrictive film.

Further, Japanese Patent Application Laid-Open No. 5-52678 discloses an F
An e-Co (Co, 30 to 60 wt%) alloy is used, and at least one of Mn, V, and Nb is added as an additive element in 5w.
It has been proposed to employ a magnetostrictive film formed by a plasma spraying method in which the content of oxygen is set to t% or less and the content of oxygen is set to 0.2 wt or less.

[0005]

As described above, various methods have been proposed for manufacturing a magnetostrictive film of a magnetostrictive torque sensor and its composition. However, the most important factor in the magnetostrictive film is magnetostriction sensitivity. How to select an excellent magnetostrictive film has never been known before,
However, there was no effective means other than obtaining the magnetostriction sensitivity by repeatedly manufacturing and testing while changing the composition ratio little by little.

For example, even in the composition range proposed by the above-mentioned prior art, it is completely unclear at which composition point the most sensitive magnetostrictive film can be obtained, but it is suggested that this degree is only good. Not just. This means that the magnetostrictive film is composed of two or more main constituent elements, and it is enormous labor, time and cost to manufacture and test each magnetostrictive torque sensor by changing the composition ratio of each main constituent element one by one. Because it is difficult.

In view of this problem, the present inventors have found a technique for easily selecting a high-sensitivity magnetostrictive film, and thereby have made it possible to select a high-sensitivity magnetostrictive film among the magnetostrictive films of the respective component systems. Accordingly, an object of the present invention is to provide a magnetostrictive torque sensor having a highly sensitive magnetostrictive film.

[0008]

According to the first aspect of the present invention, there is provided a method for selecting a magnetostrictive film of a magnetostrictive torque sensor, wherein the outer peripheral surface of a shaft made of a metal is covered with the magnetostrictive film. , Relative permeability μs, Young's modulus E,
When the magnetostriction constant is λ, a magnetostrictive film having a composition in which the absolute value of (μs · E) ^1/2 · λ is 5 × 10 ⁴ or more is selected. This makes it possible to estimate a highly sensitive magnetostrictive film using a simple physical property data test or an existing physical property data table.

According to the magnetostrictive film of the magnetostrictive torque sensor of claim 2, the magnetostrictive film of the magnetostrictive torque sensor of claim 1 further has a relative magnetic permeability μs of 170 or more and a Young's modulus E
Is 14000 or more, the magnetostriction constant λ is 30 or more, and Ni
Of 85 wt% or more is adopted. In this way, a highly sensitive magnetostrictive film could be realized.

According to the magnetostrictive film of the magnetostrictive torque sensor of the third aspect, the magnetostrictive film of the magnetostrictive torque sensor of the second aspect further employs a Ni-C-based magnetostrictive film containing 0.01 to 2 wt% of C. Is done. In this way, a highly sensitive magnetostrictive film could be realized. According to the magnetostrictive film of the magnetostrictive torque sensor according to claim 4, the magnetostrictive film of the magnetostrictive torque sensor according to claim 1 further has a magnetic permeability μs of 350 or more, a Young's modulus E of 18000 or more, and a magnetostriction constant λ of 17 or more. And 30 to 90% by weight of Ni and 0.1 to 1% of Al.
A 5 wt% Ni-Fe-Al-based magnetostrictive film is employed. In this way, a highly sensitive magnetostrictive film could be realized.

According to the magnetostrictive film of the magnetostrictive torque sensor according to claim 5, the magnetostrictive film of the magnetostrictive torque sensor according to claim 4 further includes Ni-Fe further containing 0.01 to 2 wt% of C.
-An Al-C magnetostrictive film is employed. If you do this,
A highly sensitive magnetostrictive film was realized. According to the magnetostrictive film of the magnetostrictive torque sensor according to claim 6, the magnetostrictive film of the magnetostrictive torque sensor according to claim 1 further has a relative magnetic permeability μ.
s is 150 or more, Young's modulus E is 15000 or more, the absolute value of magnetostriction constant λ is 25 or more, and Ni is 80 to 98 wt.
% Is adopted. In this way, a highly sensitive magnetostrictive film could be realized.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the following examples. N used as a magnetostrictive film
As the i-Co-based alloy, Ni is more preferably 90%.
It is preferable to contain 含 む 95 wt%. Other auxiliary additive elements that can be included include Mn, Mo, S
i, Cr, Cu, etc. can be added in an amount of about 0.1 to 10 wt%.

Ni--Fe--Al--C used as a magnetostrictive film
As the system magnetostrictive film, Ni is more preferably 40 to 80 watts.
It is preferable that t% and Al contain 5 to 10 wt%. Other auxiliary additive elements that can be included include M
n, Mo, Si, Cr, Cu, etc. 0.1 to 10 wt.
% Can be added. As the shaft, SC
Alloy steel such as r and SCM, carbon steel, and non-magnetic stainless steel can be used.

[0014]

【Example】

Embodiment 1 FIG. 1 shows the shape of a magnetostrictive film of a magnetostrictive torque sensor used in an experiment. Reference numeral 1 denotes a shaft, and 2 denotes a bobbin fitted to the shaft 1 with a small gap.

The bobbin 2 has a pair of coil grooves in the front and rear directions in the axial direction. Excitation coils 3 and 4 are individually wound above the two coil grooves, and a detection coil 5 and a detection coil 5 are provided below the both coil grooves.
6 are individually wound. Bobbin 2 in one coil groove
A first magnetostrictive film 7 is attached to the outer peripheral surface of the shaft 1 facing the other, and a second magnetostrictive film 8 is applied to the outer peripheral surface of the shaft 1 facing the bobbin 2 to the other coil groove. Is being worn. The number of turns of both excitation coils 3 and 4 is equal, and the number of turns of both detection coils 5 and 6 is set equal.

FIG. 2 shows the configuration of the detection circuit. When a sine wave AC voltage of a predetermined frequency (here, 50 kHz) is applied to the exciting coils 3 and 4 connected in series, the magnetostrictive films 7 and 8 modulate the AC magnetic field according to the torsional stress applied to the shaft 1. Then, since the signal voltages induced in the two detection coils 5 and 6 change in the opposite direction, the signal voltages of the two detection coils 5 and 6 are detected by the detectors 9 and 10, respectively, and the voltage amplifier 1
If the signal is amplified by 1 and 12, and the difference between the two signal voltages is obtained by the differential amplifier 13, a signal voltage substantially proportional to the stress of the shaft 1, that is, the torque, can be obtained.

The magnetostrictive films 7 and 8 are formed by plasma spraying, and thereafter, by cutting, a number of short strips extending in directions opposite to each other and parallel at 45 degrees to the axial direction as shown in FIG. It consists of. These configurations described above are general as a magnetostrictive torque sensor structure, and are well known, so detailed description will be omitted.

The diameter of the shaft 1 is 17 mm and the length is 12
A sample having a thickness of 0 mm and processed using SCr420 as a raw material was prepared, the outer peripheral surface thereof was blasted, and plasma spraying was performed. The plasma spraying was performed in the atmosphere, and a 0.3 mm thick magnetostrictive film was formed on the outer peripheral surface of the shaft 1. Next, the shaft 1 is held at 950 ° C. for 3 hours in a CO (carbon monoxide) atmosphere, and then at 850 ° C. for 1.5 hours.
and then oil quenching to 130 ° C.
After holding at 0 ° C. for 2 hours, a carburizing heat treatment for air cooling and tempering was performed.

Next, as shown in FIG. 1, a processing process was performed on the magnetostrictive film to form a film having a Chevron pattern shape, that is, a large number of the above-described bands. The width of each band is about 2.2mm,
The length was 10 mm, the film thickness was 0.2 mm, the right half of the axis was inclined at + 45 ° with respect to the longitudinal direction, and the left half was inclined at −45 ° with respect to the longitudinal direction. The interval between the bands was about 2.2 mm. The following theoretical analysis was performed to determine the composition of the magnetostrictive film. (Theoretical Analysis on Relationship between Magnetostrictive Sensitivity and Each Physical Property Value of Magnetostrictive Film) When the magnetic field H, the magnetic flux density B, the stress σ, and the strain e slightly change, the relationship between the respective changes is shown as follows. It is.

First, since B is a function of H and σ, B
= B (H, σ), and e is also a function of H and σ.
= (H, σ), Here, μs is a relative magnetic permeability expressed by a partial differential coefficient under a constant stress condition, μo is a vacuum magnetic permeability, and E is a Young's modulus. Here, d is a magnetostriction conversion constant, and d 'is an inverse magnetostriction conversion constant. Here, if B and △ e are simply written as B and e, Can be rewritten. Next, assuming that the ratio of the energy which is converted into elastic energy and is stored in the substance is k ² among the magnetically applied energy due to minute changes in B and H, Becomes Here, k is an electromechanical conversion constant. Also,
Since it is considered that d = d ′ from the Maxwell relational expression, using the above expression, B = (1−k ² ) μsμo · H + (μsμo · E) ^1/2
・ Ek is obtained. Here, (1−k ² ) μs μo · H is a magnetic flux density change based on an external magnetic field change, and (μs μo
E) ^1/2 · e · k is considered to be a change in magnetic flux density based on magnetostriction. Furthermore, assuming isotropic magnetostriction and letting the static magnetostriction constant be λ, the change in magnetic flux density based on the magnetostriction is Here, 1 is the length and dl is the amount of change. After all, the change in magnetic flux density based on magnetostriction, that is, the sensor sensitivity,
(Μsμo · E) Assuming that ^1/2 · λ is α, magnetic permeability (relative magnetic permeability × vacuum magnetic permeability), Young's modulus, magnetostriction conversion constant,
It was found that there was a relationship between the electromechanical coupling constant and α · k. It was found that if the change in the electromechanical conversion constant k before and after the application of the torque was ignored, the sensor sensitivity could be regarded as having a relationship α with respect to the relative permeability μs, the Young's modulus E, and the magnetostriction conversion constant λ.

When a causal relationship was examined by multiple regression analysis using multivariate analysis between the sensor sensitivity and the magnetic properties of various magnetic materials, the sensor sensitivity showed a deep correlation between the initial rise of magnetostriction and the magnetic permeability. I also knew it had. next,
Based on the above findings, the present inventors have previously known physical property values μs, E, and λ for three types of component sprayed magnetostrictive films.
Are selected from the compositions having large compositions.
~ C) was formed and the sensitivity was examined. For comparison, the sensitivity was also examined for a total of four types of comparative magnetostrictive films (d to g). The result is shown in FIG. FIG. 3 demonstrates that α and sensitivity (output) have an extremely strong proportional relationship in many magnetostrictive films of different component systems. The characteristics shown in FIG. 3 are measured at a measurement frequency of 50 KHz and an excitation voltage of 2 V in the magnetostrictive torque sensor shown in FIGS. 1 and 2, and the value (output) on the vertical axis in FIG. The ability value excluding the voltage amplification is shown.

As a result, the composition range in which excellent magnetostriction sensitivity (output) was obtained was found for each component system. Table 1 shows the results.

[0023]

[Table 1] Hereinafter, each of the above films will be described in more detail.

The Ni—C sprayed film, ie, the product a of the embodiment, is manufactured by the above-described manufacturing process.
00 wt% nickel, and carbon C is
Approximately 1 wt% is added by reduction heat treatment. Ni
The Fe-Al-C sprayed film, that is, the product of Example b was manufactured by the above-described manufacturing process, and the composition of the magnetostrictive film was 43 wt% of Ni, 1 wt% of Al, and 2 wt% of C.
%, And the balance is almost Fe. In addition, Co, Mo, Si, Cu, Mn, B, Cr, and the like may be contained as a total of about 10 wt% as an additional element.

The Ni—Co film, ie, Example product c, is a bulk film produced by the casting and forging method, and contains 95 wt% of Ni. The SCr film, ie, the non-sprayed comparative example product d, is a bulk film made from a commercially available round bar, and has a thickness of 0.9 to 1.2 watts.
Contains t% Cr. The Co bulk film, ie, the comparative example product e, and the Ni bulk film, ie, the comparative example product f, are also 100 wt% bulk films produced by the casting and forging method.

The Ni sprayed film, ie, the comparative example g, is obtained by omitting the reduction heat treatment step after the completion of the thermal spraying in the manufacturing steps described above. From various tests including this test and the above theoretical analysis, the following was found. The Ni-based magnetostrictive film has a relative magnetic permeability μs of 170 or more and a Young's modulus E of 1400.
0 or more, the magnetostriction constant λ is 30 or more, and Ni is 85 wt.
% Of a material having a composition containing at least
A material having a composition further containing 0.01 to 2 wt% of C in the i-based magnetostrictive film, and a Ni—Fe—Al-based magnetostrictive film having a relative magnetic permeability μs of 350 or more, a Young's modulus E of 18000 or more, and a magnetostriction constant λ of 17 As described above, 30 to 90 wt% of Ni, A
material containing 0.1 to 15 wt% of Ni, Ni-Fe-
In the Al—C magnetostrictive film, a material having a composition further containing 0.1 to 2 wt% of C in the above Ni—Fe—Al magnetostrictive film;
A material having a relative magnetic permeability μs of 180 or more, a Young's modulus E of 18000 or more, an absolute value of the magnetostriction constant λ of 25 or more, and a composition containing 80 to 98 wt% of Ni in the i-Co-based bulk magnetostrictive film.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing shapes of a magnetostrictive film and a shaft of a magnetostrictive torque sensor used in an experiment.

FIG. 2 is a circuit diagram showing a configuration of a detection circuit of a magnetostrictive torque sensor used in an experiment.

FIG. 3 is a characteristic diagram showing a relationship between an output voltage (sensitivity) of each sample and a composite physical property parameter α.

[Explanation of symbols]

 1 is a shaft, 7 and 8 are magnetostrictive films

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Atsunao Ito 2-1-1 Asahi-cho, Kariya-shi, Aichi Pref. Aisin Seiki Co., Ltd.

Claims (6)

[Claims] 1. A magnetostrictive film of a magnetostrictive torque sensor in which a magnetostrictive film is attached to an outer peripheral surface of a shaft made of metal. When a relative magnetic permeability is μs, a Young's modulus is E, and a magnetostriction constant is λ, (μs · E) ^1/2 · λ absolute value magnetostrictive film of the magnetostrictive torque sensor, which is a magnetostrictive film in which the composition 5 × 10 ⁴ or more. 2. The magnetostrictive film according to claim 1, wherein said magnetostrictive film has a relative magnetic permeability μs of 170 or more and a Young's modulus E.
Is 14000 or more, the magnetostriction constant λ is 30 or more, and Ni
Of a Ni-based magnetostrictive film containing at least 85 wt% of Ni. 3. The magnetostrictive film of a magnetostrictive torque sensor according to claim 2, wherein said magnetostrictive film further contains 0.01% to 2% by weight of Ni-Ni.
A magnetostrictive film for a magnetostrictive torque sensor, comprising a C-based magnetostrictive film. 4. The magnetostrictive film according to claim 1, wherein said magnetostrictive film has a relative magnetic permeability μs of 350 or more and a Young's modulus E.
Is 18000 or more, the magnetostriction constant λ is 17 or more, and Ni
Containing 30 to 90 wt% of Al and 0.1 to 15 wt% of Al
A magnetostrictive film for a magnetostrictive torque sensor, comprising an i-Fe-Al-based magnetostrictive film. 5. A magnetostrictive film for a magnetostrictive torque sensor according to claim 4, wherein said magnetostrictive film further contains 0.1 to 2 wt% of C.
A magnetostrictive film for a magnetostrictive torque sensor, comprising an e-Al-C-based magnetostrictive film. 6. The magnetostrictive film according to claim 1, wherein said magnetostrictive film has a relative magnetic permeability μs of 150 or more and a Young's modulus E.
Is 15000 or more, the absolute value of the magnetostriction constant λ is 25 or more, and a magnetostrictive film of a magnetostrictive torque sensor comprising a Ni—Co-based magnetostrictive film containing 80 to 98 wt% of Ni.