JPH05340826A - Mangetostriction type torque sensor - Google Patents

Abstract

PURPOSE:To obtain a magnetostriction torque sensor which can be improved in torque detection sensitivity even under a high-temperature or high-torque condition. CONSTITUTION:In the title torque sensor which magnetically detects the torque transmitted to a power transmission shaft 1 by utilizing an effect of reverse magnetostriction, crystalline layers 2 and 3 of (Fe0.9Co0.1)0.78SixBy (where X+Y=0.22) are formed on the surface of the shaft 1 with a mutual diffusion layer 10 in between. In the layer 10, the crystalline layers 2 and 3 and shaft 1 are uniformly joined to each other at an atomic level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetostrictive torque sensor which measures the torque transmitted to a power transmission shaft in a non-contact manner by utilizing the inverse magnetostrictive effect of a magnetic alloy.

[0002]

2. Description of the Related Art Ferromagnetic materials have the property that when magnetized, their dimensions change, and conversely, when an external force is applied to elastically deform them, their magnetic permeability changes. The former is called the magnetostrictive effect and the latter is called the inverse magnetostrictive effect. The saturation magnetostriction coefficient λ _S is used as a measure of the magnitude of these effects. A sensor that magnetically detects the torque applied to the rotating shaft by utilizing the inverse magnetostrictive effect is called a magnetostrictive torque sensor.

Generally, in a power transmission shaft (rotating shaft) used for a prime mover, a machine tool, etc., torque applied to the power transmission shaft is measured for output control or power fluctuation control. A magnetostrictive torque sensor is used to measure this torque. Conventionally, the "torque sensor" disclosed in Japanese Patent Laid-Open No. 63-158432 is manufactured by fixing a magnetic metal ribbon on the surface of a power transmission shaft with a synthetic resin adhesive or the like to form a magnetostrictive layer. There is. In this torque sensor, torque is applied to the power transmission shaft, the stress of the power transmission shaft due to this torque is introduced into the magnetostrictive layer, and the change in permeability due to the inverse magnetostriction effect of the magnetostrictive layer at this time is detected from the outside without contact. To do.

[0004]

However, in such a conventional magnetostrictive torque sensor, depending on the magnitude of the torque applied to the power transmission shaft or the temperature of the operating environment of 200 ° C. or more, the magnetic metal is used. There is a problem in that the joint between the ribbon and the power transmission shaft is deteriorated, the correlation between the applied torque and the change in the detected magnetic permeability is broken, and the torque detection accuracy is reduced. The problem is that the ratio between the torque applied to the power transmission shaft and the joint strength of the synthetic resin adhesive decreases as the torque increases, and the stress generated in the power transmission shaft is sufficiently applied to the magnetostrictive layer of the magnetic metal ribbon. It is assumed that it will not be able to be introduced in. Alternatively, it is assumed that it is caused by a change with time of the synthetic resin adhesive itself, deterioration by heat at a temperature of 200 ° C. or higher, or the like.

Therefore, an object of the present invention is to provide a magnetostrictive torque sensor capable of improving the torque detection sensitivity even in a use environment such as high temperature and high torque.

[0006]

In the magnetostrictive torque sensor according to claim 1, a magnetostrictive torque sensor for magnetically detecting torque transmitted to a power transmission shaft by utilizing an inverse magnetostrictive effect is used. It has a crystalline magnetic alloy layer formed on the surface of the shaft through an interdiffusion layer.
Examples of the crystalline magnetic alloy include Fe (Co) -S
In an i-B type alloy, (Fe _0.9 Co _0.1 ) _X (Si
_m B _n ) _Y , X + Y = 1.0, 0.75 <X <0.
90, within the range of 0.25 <Y <0.10, and m + n
= 1, alloys in the range of 0.2 <m <0.8, 0.2 <n <0.8, (Fe _0.9 Co _0.1 ) _0.78 Si _{X BY} [however, X + Y = 0.22], Co -40% Fe, Fe-1
3% Al, TbFe ₂ , Tb-30% Fe, Tb (Co
Fe) ₂ , Tb (NiFe) ₂ , TbFe ₃ and DyFe ₂ .

[0007]

In the magnetostrictive torque sensor according to the first aspect of the present invention, the magnetic alloy film is fixed to the surface of the power transmission shaft by, for example, high frequency fusion bonding. At this time, an interdiffusion layer is formed at the interface between the magnetic alloy film and the power transmission shaft. The magnetic alloy layer is bonded to the surface of the power transmission shaft with good adhesion through the mutual diffusion layer. Therefore, it is possible to obtain a magnetostrictive torque sensor having high sensitivity and high durability even in an environment of high temperature and high torque and having sufficient magnetic characteristics.

[0008]

Embodiments of the magnetostrictive torque sensor according to the present invention will be described below with reference to the drawings. The magnetostrictive torque sensor is configured as follows. That is, as shown in FIG. 3, which is a schematic view showing a magnetostrictive torque sensor according to an embodiment of the present invention, a cylindrical bobbin 4 is provided so as to surround the power transmission shaft 1. The gap between the bobbin 4 and the power transmission shaft 1 is 2 mm or more. The exciting coil 5 is wound around the bobbin 4. The exciting coil 5 is connected to an AC power supply (not shown) of several kHz to several hundred kHz. Therefore, the power transmission shaft 1
An AC magnetic field that is sufficiently saturated is applied to the magnetostrictive layers 2 and 3 formed on the surface. The detection coil 6 is wound around the outer circumference of the excitation coil 5 so that the detection coil 7 is located above the magnetostrictive layer 2 and the detection coil 7 is located above the magnetostrictive layer 3. One ends of the detection coils 6 and 7 are connected to each other, and the other ends thereof are connected to a detector and an amplifier (not shown), respectively.
Outputs a voltage.

FIG. 1 shows a magnetostrictive device according to an embodiment of the present invention.
It is sectional drawing which shows the principal part of a luc sensor. Power transmission shaft
The magnetostrictive layers 2 and 3 are provided on the surface of
Is formed. These magnetostrictive layers 2 and 3 are crystalline magnetic
A layer made of an alloy, for example, Fe (Co) -Si-B
In the alloys of the series, (Fe_0.9Co_0.1)_X(Si_mB_n)_Y, X
+ Y = 1.0, 0.75 <X <0.90, 0.2
Within the range of 5 <Y <0.10, and m + n = 1
When within the range of 0.2 <m <0.8 and 0.2 <n <0.8
Gold, (Fe_0.9Co_0.1)_0.78Si_XB_Y[However, X + Y =
0.22], Co-40% Fe, Fe-13% Al, T
bFe₂, Tb-30% Fe, Tb (CoFe)₂, Tb
(NiFe)₂, TbFe₃, DyFe₂And the magnetostriction constant of
10 x 10 ^-6It is formed of the above magnetic alloy. This phase
The interdiffusion layer 10 forms a power transmission shaft with this crystalline magnetic alloy.
It is a layer formed by mutual diffusion with the steel material for use.

Therefore, when a torque is applied to the power transmission shaft 1, the magnetic permeability of the strip-shaped magnetostrictive layer 2 which receives tension in its longitudinal direction increases. On the contrary, in the magnetostrictive layer 3 which receives tension in the width direction, its magnetic permeability decreases. As a result, there is a difference in mutual inductance between the excitation coil 5 and the detection coils 6 and 7. By detecting these changes, the torque applied to the power transmission shaft 1 can be measured. Further, the magnetostrictive layers 2, 3 and the coils 5,
Since the electromagnetic coupling between 6 and 7 is rotationally symmetrical, the change in magnetic permeability can be detected regardless of the rotation of the power transmission shaft 1. The change in magnetic permeability may be detected using a magnetic head.

The method of manufacturing this torque sensor will be described below. First, the material of the power transmission shaft 1 is SNCM.
439 steel with a diameter of 20 mm and a length of 100 m
Prepare a cylindrical body of m. Next, as shown in FIG. 2, the surface of the power transmission shaft 1 is masked with a mask 100 (hatched portion in the figure) having a predetermined pattern. This mask 10
At 0, a chevron-shaped opening is formed.

Next, powders of Fe, Co, Si and B are mixed in a predetermined composition. For example, Fe: 82.4% by weight,
The composition is such that Co: 9.7 wt%, Si: 4.7 wt%, B: 3.2 wt%. The vehicle is added to the mixed powder blended in this composition. This vehicle is made of acrylic resin with α-
It contains 5% by weight of terpineol. And
The mixed powder and the vehicle are sufficiently kneaded, and the mixed powder is dispersed in the vehicle to form a thick suspension (slurry). This slurry is applied to the surface of the power transmission shaft 1. The power transmission shaft 1 is dried at a temperature of 120 ° C. for 10 to 20 minutes. For example, this coating and drying are repeated until the slurry has a coating thickness of 100 μm. Next, the power transmission shaft 1 is pre-baked for 10 minutes at a temperature in the range of 320 to 380 ° C. As a result, the vehicle of the slurry applied to the power transmission shaft 1 is decomposed. Only the Fe-Co-Si-B film is fixed to the surface of the power transmission shaft 1 (the chevron-shaped opening).

Next, together with the mask 100, the mask 10
The Fe-Co-Si-B film formed on the oxide film 0 is lifted off. As a result, the strip-shaped Fe-Co-Si-B films (magnetostrictive layers 2, 3) are paired with each other, and the magnetostrictive layers 2, 3 are formed.
Is formed so that the longitudinal direction thereof is ± 45 ° with respect to the axial direction of the power transmission shaft 1 (see FIG. 3). These magnetostrictive layers 2 and 3 are thus ± 4 with respect to the axial direction of the power transmission shaft 1.
The reason why it is arranged at 5 ° is that the maximum tensile stress and the maximum compressive stress generated by the twist of the power transmission shaft 1 are both generated at a direction of 45 ° with respect to the axial direction of the power transmission shaft 1. A magnetic alloy ribbon (ribbon) such as Fe-Co-Si-B is prepared in advance, the magnetic alloy ribbon is cut into strips, and predetermined spots are spot-welded at positions 2 and 3 in FIG. Alternatively, it may be temporarily fixed with a Cr wire or the like.

Next, the interface between the Fe-Co-Si-B film and the power transmission shaft 1 is evenly bonded at the atomic level using a high-frequency fusion bonding device. For example, vacuum degree: 10 ^-3 T
Melt diffusion bonding is performed in a vacuum of orr under the conditions of high frequency output: 5 kW and time: 10 seconds. As a result, Fe-Co-S
A layer 10 (see FIG. 1) in which the composition of the i-B film and the composition of the power transmission shaft 1 are mutually diffused is formed at this interface. The (Fe _0.9 Co _0.1 ) ₇₈ Si _{X BY} layer is formed on the surface of the power transmission shaft 1 via the mutual diffusion layer 10. Then, the (Fe _0.9 Co _0.1 ) ₇₈ Si _{X BY} layer and the power transmission shaft 1
The joining strength with and becomes 20 kg / mm ² or more, and the durability becomes 10 ⁷ cycles or more. One cycle is one rotation when torque is applied.

In the magnetostrictive torque sensor of this embodiment having the magnetostrictive layers 2 and 3 thus formed, the change in the inductance of the magnetostrictive layers 2 and 3 with respect to the torque applied to the power transmission shaft 1 (torque detection sensitivity). FIG. 4 shows the result of the examination at room temperature. In this figure, ● indicates the characteristic of the magnetostrictive torque sensor according to the present embodiment. And ○ indicates the characteristics of a magnetostrictive torque sensor in which an amorphous magnetostrictive layer is formed using a conventional synthetic resin adhesive (epoxy adhesive) and the surface of the magnetostrictive layer is covered with a non-magnetic layer. is there. As is clear from this result, in the magnetostrictive torque sensor of the present embodiment, it is possible to obtain large magnetic characteristics comparable to the amorphous magnetostrictive layer in a wide torque range.

Further, when the characteristics with respect to the operating environment temperature were examined, the results shown in FIG. 5 were obtained. Also in this figure, ● indicates the characteristics of the magnetostrictive torque sensor of the present embodiment, and ○ indicates the characteristics of the conventional magnetostrictive torque sensor. As is clear from this result, the magnetostrictive torque sensor of this embodiment provides stable detection sensitivity in a wide range from a low temperature range to a high temperature range of 200 ° C. or higher. The environmental temperature when applied to a prime mover, for example, an internal combustion engine (automobile engine) is about 170 ° C.,
Stable detection sensitivity is ensured even in this environment.

Therefore, since the magnetic alloy layer is strongly formed at the atomic level on the surface of the power rotating shaft via the interdiffusion layer, a high torque, especially in an engine of an automobile, can be obtained.
Even in severe operating environments such as high temperatures, the sensitivity and linearity of stress-magnetic property conversion are excellent.

[0018]

As described above, according to the magnetostrictive torque sensor of the present invention, the torque detection sensitivity can be improved even in a use environment such as high temperature and high torque.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a magnetostrictive torque sensor according to an embodiment of the present invention.

FIG. 2 is a diagram showing a power transmission shaft for explaining a method of manufacturing a magnetostrictive torque sensor according to an embodiment of the present invention.

FIG. 3 is a schematic diagram showing a magnetostrictive torque sensor according to an embodiment of the present invention.

FIG. 4 is a graph showing changes in torque detection sensitivity with respect to torque of a magnetostrictive torque sensor according to an example of the present invention and a conventional example.

FIG. 5 is a graph showing changes in torque detection sensitivity with respect to operating temperature of the magnetostrictive torque sensor according to the example of the present invention and the conventional example.

[Explanation of symbols]

 1 Power Transmission Shaft 2 Magnetostrictive Layer (Crystalline Magnetic Alloy Layer) 3 Magnetostrictive Layer (Crystalline Magnetic Alloy Layer) 10 Mutual Diffusion Layer

[Procedure amendment]

[Submission date] July 29, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

Claims (1)

[Claims] 1. A magnetostrictive torque sensor for magnetically detecting torque transmitted to a power transmission shaft by utilizing an inverse magnetostrictive effect, wherein a crystalline magnetic alloy is formed on the surface of the power transmission shaft via an interdiffusion layer. A magnetostrictive torque sensor having a layer.