JPH04329326A - Torque detection apparatus - Google Patents

Abstract

PURPOSE:To obtain torque output characteristics stabilized from a low torque to a high torque and to improve manufacture of shape magnetic anisotropy parts. CONSTITUTION:A surface part of a measured axis 2 is formed by melting a magnetostrictive material 2b made of Fe-Al alloy into a single body. On the surface part of the measured axis 2, a smoothly curved surface is formed by plastic processing and shape magnetic anisotropy parts 5a, 5b composed of recess shaped parts 3a, 3b and projection shaped parts 4a, 4b are provided with a fixed angle to the axial direction of the measured axis 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque detection device used to detect torque applied to a shaft to be measured.

0002

2. Description of the Related Art Conventional torque detecting devices of this type include, for example, the one disclosed in Japanese Patent Application Laid-Open No. 185136/1986 as shown in FIG.
There is one shown in the publication.

A torque detection device 101 shown in FIG. 6 has a plurality of grooves 103 that are inclined left and right at intervals in the axial direction formed on the surface of a shaft 102 to be measured in the circumferential direction to form a shape magnetic anisotropy portion. and a measured axis 1 facing the shape magnetic anisotropy section.
Coils 104 and 105 are placed outside the coils 104 and 105 with a gap 106 in between, and the yoke 10 is placed outside the coils 104 and 105.
7.

In the torque detection device 101 having such a structure, the coils 104 and 105 are combined with resistors 111 and 112 to form a bridge circuit, as illustrated in FIG. An excitation oscillator 113 is connected between C and a differential amplifier 114 is connected between connection points B and B', so that when torque T is applied to the shaft to be measured 102, the It is possible to extract a detection output with a torque-output characteristic.

The torque detection device 101 of this type detects the magnetostrictive component of the shaft 102 to be measured.
There is no output fluctuation due to rotation, and stable output can be obtained over a wide range from static torque to high-speed rotating torque, making it useful as a non-contact torque detection means.

[0006]

However, in such a conventional torque detection device 101, when providing the shape magnetic anisotropy portion on the shaft 102 to be measured, the groove 103
This is done by forming by cutting, but since cutting may cause stress concentration especially when high torque is applied, it is necessary to maintain stable torque-output characteristics from low torque to high torque. In particular, the measured axis 102
When hard magnetostrictive materials such as Fe-Al alloys are used as the material, machinability is poor, drill bits often break, and machining requires a considerable amount of time, which hinders mass production. However, there are problems in that there are many problems, and it has been a challenge to solve these problems.

[0007]

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art. The shape is designed to prevent stress concentration from occurring even when high torque is applied.
In addition to making it possible to obtain stable torque-output characteristics from low torque to high torque, it also improves the manufacturability of the shape magnetic anisotropy part, making it possible to mass-produce the shaft to be measured. It is an object of the present invention to provide a torque detection device according to the present invention.

[0008]

[Means for Solving the Problems] The present invention provides a shaft to be measured such as a power transmission shaft, an excitation means for forming a magnetic circuit in which the shaft to be measured is a part of a magnetic path, and a magnetostriction of the shaft to be measured. In a torque detection device comprising a detection means for detecting a component, the surface portion of the shaft to be measured is formed by fusion and integration with a magnetostrictive material made of a Fe-Al alloy, and the surface portion of the shaft to be measured is It is characterized by having a shape magnetic anisotropic part formed by plastic working into a smooth curved shape and consisting of an uneven part forming a predetermined angle with respect to the axial direction of the shaft to be measured. In an embodiment, the plastic working is plastic working under heating at a temperature of 400° C. or higher at least on the surface portion of the shaft material to be measured, the surface portion of which is fused and integrated with a magnetostrictive material made of an Fe-Al alloy. The structure of the invention related to such a torque detection device is a means for solving the above-mentioned conventional problems.

In the torque detection device according to the present invention, the surface portion of the shaft to be measured is formed by fusion and integration with a magnetostrictive material made of Fe-Al alloy. In this case, the shaft base of the shaft to be measured is As such, it is possible to use materials with a high yield point, and it is desirable to actively use high yield point materials as necessary. Steel materials for machine structures, for example, carbon steel materials for machine structures (SC materials, S
-CK materials, etc.), alloy steel materials for machine structures (SCr materials,
SCM materials, SNC materials, SNCM materials, etc.) are used, and materials with improved yield points and the like are used by appropriately changing additive components and compositions.

[0010] In addition, as a magnetostrictive material made of an Fe-Al alloy that is formed by fusing and integrating the surface portion of the shaft to be measured, not only the Fe-Al alloy but also this Fe-Al
A Fe-Al alloy is used, which has improved magnetostriction and the like by appropriately changing the additive components and composition of the alloy.

[0011] The material having a high yield point, for example, which constitutes the shaft base of the shaft to be measured, and the Fe-Al alloy, which is a high magnetostrictive material, formed on the surface of this shaft base are alloyed with each other in metallographic structure. It is desirable that the two be alloyed by metallographically merging them, such as TIG welding, plasma powder welding,
Examples include laser welding, electron beam welding, and diffusion.

In the torque detection device according to the present invention, the surface portion of the shaft to be measured is made of Fe-Al as described above.
A magnetostrictive material made of a magnetostrictive alloy is fused and integrated, and the surface portion of the shaft to be measured is formed into a smooth curved shape by plastic working and at a predetermined angle with respect to the axial direction of the shaft to be measured. In this case, at least the surface of the axis to be measured is subjected to plastic working under heating at 400°C or higher to improve the shape magnetic anisotropy. It is desirable to form a section.

In this case, the heating means for the shaft to be measured is as follows:
In addition to being able to use an electric heating furnace, it is also possible to heat only the surface portion using high frequency induction heating.

[0014] The reason why it is desirable to carry out plastic working at a temperature of 400°C or higher is because the toughness of Fe-Al alloys is greatly improved when heated to 400°C or higher, and the This is because the shape magnetic anisotropy portion can be formed even more easily.

[0015] In this way, a shape magnetically anisotropic part having a smooth curved surface shape is formed by plastic working using a mold, but if plastic working is performed at too high a temperature, Since the life of the mold will be reduced, it is desirable that the temperature be 900°C or less.

[0016]

Effect of the Invention In the torque detecting device according to the present invention, the surface portion of the shaft to be measured is formed by fusion and integration with a magnetostrictive material made of Fe-Al alloy, and the surface portion of the shaft to be measured is subjected to plastic processing. Since the shape magnetic anisotropy part is formed with a smooth curved surface shape and consists of an uneven part forming a predetermined angle with respect to the axial direction of the shaft to be measured, the shape magnetic anisotropy part is Compared to forming by cutting, stress concentration is less likely to occur, and in particular, stress concentration does not occur even when high torque is applied, so stable torque-output characteristics can be obtained from low torque to high torque. In addition, the formability is much better than that obtained by cutting, and the manufacturability of the shape magnetically anisotropic part is further improved.

[0017]

[Embodiment] Next, an embodiment of the torque detection device according to the present invention will be described.

FIG. 1 shows an embodiment of a torque detection device according to the present invention.
As shown in FIG. 2, Fe-
A shaft 2 to be measured is provided, which is formed by metallographically fusing magnetostrictive material 2b made of an Al-based alloy into one piece, and a surface portion of the shaft 2 to be measured is formed into a smooth curved shape by plastic working. and concave portions 3a and 3b forming a predetermined angle with respect to the axial direction of the shaft 2 to be measured, and a convex portion 4 formed relatively by the formation of these concave portions 3a and 3b.
Shape magnetic anisotropy parts 5a and 5b consisting of a and 4b are provided,
Further, coils 6a and 6b are arranged on the outer circumferential side of the shaft 2 to be measured so as to face the shape magnetic anisotropy parts 5a and 5b with a gap 7 interposed therebetween, and a yoke 8 is provided on the outside of the coils 6a and 6b. It is something that does.

In this case, the coils 6a and 6b form a bridge circuit together with the resistors (111, 112) in a circuit configuration similar to that shown in FIG. It serves both as an excitation means for forming the magnet and as a detection means for detecting the magnetostriction component of the shaft 2 to be measured.

The process of manufacturing the shaft to be measured 2 in the torque detection device 1 having such a structure will be explained.

In this embodiment, in the torque detecting device 1 having the structure shown in FIG. 1, carbon steel for mechanical structures corresponding to JIS S25C is used as the material for the shaft base 2a having a high yield point of the shaft 2 to be measured. Using a material processed to a diameter of 18.5 mm, a Fe-Al alloy consisting of 13% by weight of Al and the balance of Fe was fused metallographically to the surface by plasma powder welding (PPW) as a high magnetostrictive material 2b, and then, By cutting the outer periphery, a shaft material 2' to be measured having a diameter of 20 mm was obtained, as shown in FIG. 3, in which the high magnetostrictive material 2b was metallographically fused and integrated into a part of the shaft base 2a.

Next, the shaft material 2' to be measured is subjected to high frequency heating, so that at least the surface portion of the shaft material 2' to be measured becomes 400%
℃ or more, and immediately put it in a rolling machine and perform plastic working, thereby forming the concave portion 3a as shown in FIG.
, 3b and convex portions 4a, 4b formed relative to each other by forming these concave portions 3a, 3b, shape magnetic anisotropic portions 5a, 5b having smooth curved surfaces were formed. Here, the pitch of the formed uneven portions is approximately 3 mm, and the step difference is 1 mm.

Thus, as shown in FIG.
In this case, the Fe-Al alloy layer which is the magnetostrictive material 2b on the surface of the magnetostrictive material 2b forms a corrugated uneven portion, and the S25C of the shaft base 2a serves as a support to form neatly shaped magnetic anisotropic portions 5a and 5b. It has become a thing.

In the present invention, the inventor discovered that the Charpy impact value of the Fe-Al alloy, which is the magnetostrictive material 2b, changes with temperature as shown in FIG. As a result, if the shaft material to be measured, which has an integral Fe-Al alloy on its surface, is heated to 400°C or higher, it is possible to form smooth uneven parts through plastic working, that is, rolling, etc. In addition, by heating the surface part with high frequency, the underlying base material S25C is hardly heated, so the Fe-Al alloy heated to 400℃ or more Since this base material is harder, almost no plastic flow occurs in this base material, and only the magnetostrictive material 2b is deformed to form the shape magnetically anisotropic portions 5a,
It was confirmed that this method is extremely convenient for forming 5b.

In the torque detection device 1 according to the present invention, the shape magnetic anisotropy caused by the uneven portions is utilized to detect changes in the magnetic properties of the magnetostrictive material due to stress applied to the convex portions 4a and 4b. Therefore, it is desirable that most of the convex portions be made of magnetostrictive material, and the present invention provides the shaft 2 to be measured with an optimal structure.

In this way, the shape magnetic anisotropic parts 5a and 5b having smooth curved surfaces were formed by plastic working, and then heat-treated by quenching and tempering to form the shaft 2 to be measured.

The torque-output characteristics of the torque detection device 1 in this embodiment are shown in FIG. 5. As shown in FIG. 5, stable and good torque-output characteristics can be obtained from low torque to high torque. Ta.

Furthermore, in this embodiment, the axis to be measured 2
It was possible to complete the processing for forming the shape magnetically anisotropic parts 5a and 5b on each piece within 3 minutes, and the productivity was extremely good.

[0029]

[Effects of the Invention] The torque detection device according to the present invention includes a shaft to be measured, an excitation means forming a magnetic circuit in which the shaft to be measured is a part of a magnetic path, and a magnetostrictive component of the shaft to be measured. In the torque detection device comprising a detection means, the surface portion of the shaft to be measured is formed of a magnetostrictive material made of Fe-Al alloy, and the surface portion of the shaft to be measured is formed into a smooth curved shape by plastic working. Since the shape magnetic anisotropy part is formed by a concavo-convex part formed at a predetermined angle with respect to the axial direction of the shaft to be measured, the shape magnetic anisotropy part is formed by cutting. There are no areas that tend to cause stress concentration, and the magnetic anisotropic part due to unevenness is formed with a smooth curved shape, so when torque is applied, the measured shaft remains in the specified direction in the axial direction. The concavo-convex portion forming an angle causes distortion in the principal stress direction with shape magnetic anisotropy, but at this time, local stress concentration does not occur, so stable torque-output characteristics are maintained from low torque to high torque. It can be easily realized, it can be made to have excellent durability, and there is no problem such as drill breakage that occurs when forming a shape magnetic anisotropic part by cutting. Plastic working brings about the remarkable effect that it becomes possible to efficiently manufacture the shape magnetic anisotropy part in the axis to be measured.

[Brief explanation of drawings]

FIG. 1 is a partial vertical sectional view showing an embodiment of a torque detection device according to the present invention.

FIG. 2 shows an enlarged view of the structure of the shape magnetic anisotropy portion of the shaft to be measured in the torque detection device shown in FIG.
2A is an explanatory front view, and FIG. 2B is an explanatory cross-sectional view.

3 shows the structure of an intermediate product in the manufacturing process of the shaft to be measured shown in FIG. 2; FIG. 3(a) is an explanatory front view;
b) is an explanatory cross-sectional view.

FIG. 4 is a graph illustrating the relationship between the temperature of the magnetostrictive material used in the torque detection device according to the present invention and the Charpy impact value.

FIG. 5 is a graph illustrating the torque-output characteristics of the torque detection device according to the present invention.

FIG. 6 is a partial longitudinal sectional view illustrating the structure of a conventional torque detection device.

FIG. 7 is an explanatory diagram illustrating the configuration of an excitation and detection circuit used in a torque detection device of a method for detecting a change in the magnetostriction component of a shaft to be measured due to torque.

FIG. 8 is a graph illustrating torque-output characteristics of a conventional torque detection device.

[Explanation of symbols]

1 Torque detection device 2 Measured axis 2a Shaft base of shaft to be measured 2b Magnetostrictive material on the surface of the shaft to be measured 3a, 3b concave part 4a, 4b Convex part 5a, 5b Shape magnetic anisotropy part

Claims (2)

[Claims] 1. Torque detection comprising: a shaft to be measured; excitation means for forming a magnetic circuit in which the shaft to be measured is part of a magnetic path; and detection means for detecting a magnetostrictive component of the shaft to be measured. In the apparatus, the surface portion of the shaft to be measured is made of Fe-Al.
The surface portion of the shaft to be measured is formed by plastic working into a smooth curved surface shape and forms a predetermined angle with respect to the axial direction of the shaft to be measured. A torque detection device characterized in that a shape magnetic anisotropy section consisting of an uneven section is provided. 2. A claim in which the plastic working is carried out under heating at a temperature of at least 400° C. at least the surface portion of the shaft material to be measured, the surface portion of which is fused and integrated with a magnetostrictive material made of an Fe-Al alloy. 1. The torque detection device according to 1.