JPS59188968A - Torque sensor made of double layer structural amorphous magnetic thin band - Google Patents

Abstract

PURPOSE:To facilitate the manufacture of the torque sensor by making the following substance as a differential torque system sensor by using the titled magnetic thin band made of high and low magnetostriction layer having different properties of magnetic characteristic, or the magnetic layer of positive magnetic characteristic and that of negative one. CONSTITUTION:The titled magnetic thin bands 9a and 9b different from each other in spiral direction are fixed by adhesion on the outer peripheral surface of a torque transmission shaft 8. An excitation winding 10 excited to these magnetic thin bands 9a and 9b by means of an AC power source, detection windings 12a and 12b connected in reverse series, and a synchronization rectifying circuit 13 which obtains a DC voltage from the voltage induced in said windings 12a and 12b are provided. By this constitution, the impressed torque is made as the difference of permeabilities of the two magnetic thin bands 9a and 9b, which is detected by an AC bias magnetic field. Then, the influence by the material of the transmission shaft 8 and the rotational direction and rotational speed is eliminated, and accordingly the torque is detected with a high accuracy in a wide dynamic range.

Description

[Detailed Description of the Invention] The present invention is easy to manufacture, and can detect torque with high sensitivity and precision without being affected by the material of the torque transmission shaft, the direction of rotation, or the rotation speed. This issue concerns a new torque sensor with dynamic characteristics.

Torque is the most fundamental variable when controlling rotary drive parts such as electric motors and automobiles, and is also a parameter that indicates the degree of system optimization.

It can also be used for fault diagnosis. In this case, the torque sensor must be of a non-contact type, capable of detecting torque in forward rotation, reverse rotation, and at rest with high sensitivity and precision, and must have good dynamic characteristics and high reliability.

Prior art of the present invention includes a torque sensor constructed by taking advantage of the excellent mechanical properties, uniformity of the material, and remarkable magnetostrictive properties of an amorphous magnetic material.

In this torque sensor, two wide amorphous magnetic ribbons are wound and fixed around the torque transmission shaft, and each ribbon has a uniaxial magnetic anisotropy of ±45° with respect to the axial direction of the torque transmission shaft. It was possible to differentially detect the applied torque by utilizing the fact that the magnetic permeability of these two thin ribbons changes in opposite ways to each other due to the application of torque. Therefore, not only can the detection time be made highly sensitive and accurate, but the torque transmission shaft has the characteristic that it is not limited by magnetic properties.

However, from the perspective of actually applying the above-mentioned torque sensor, depending on the mechanical device to which it is applied, the process of imparting uniaxial magnetic anisotropy to two wide amorphous magnetic ribbons bonded to the torque transmission shaft may be difficult. In some cases, a problem may occur. Conventionally, the above-mentioned -axis magnetic anisotropy has been obtained by heat-treating an amorphous magnetic ribbon in a magnetic field, and by applying a torque to the torque transmission shaft in advance when bonding the ribbon to a torque transmission shaft, and then after the bonding is completed. There was no way to remove it. However, in the former case, it is not easy to create a relatively large uniaxial magnetic anisotropy, and therefore the dynamic range cannot be made very large.In the latter case, the amorphous magnetic ribbon is bonded in advance. This may not be possible in cases where it is difficult to apply torque.

The present invention is based on the same principle as the differential torque sensor using the wide amorphous magnetic ribbon.

Moreover, the present invention provides a new torque sensor that can be easily manufactured without incurring the above-mentioned manufacturing problems.

In order to achieve this object, the present invention uses an amorphous magnetic ribbon having a two-layer structure including a magnetic layer having magnetic properties. The present invention will be described in detail below using FIG. 9.

FIG. 1 shows the mechanism of generation of principal stress due to screw moment, which is the basis of the present invention. FIG. 1(a) shows a spiral cylinder 1 made of short elastic ribbons.

It is assumed that all internal stress has been removed in this state. If a screw moment 2 is added to this, uniform elastic deformation results in a complete cylinder 3 as shown in FIG. 1(b).

In this process, the short elastic ribbon is twisted around its longitudinal direction, that is, its circumferential direction, as a central axis, and a thread moment exists inside it. As a result, a principal stress is generated in the cylindrical short elastic ribbon 3.

The direction is as shown by the solid line arrow in the outer half of this strip-shaped elastic ribbon 3, and conversely, as shown in the broken line arrow in the inner half. The direction of this principal stress is in the width direction of the elastic ribbon, that is, in the direction of the central axis of the cylinder.

It forms an angle of ±45°.

If a helical cylinder 4 as shown in FIG. 2, which is constructed of two-layered amorphous magnetic ribbons with different magnetic properties, is used, the angle will be 45° or -45° with respect to the central axis of the cylinder.
Stress induction in the ° direction - axial magnetic anisotropy can be obtained. For example, if the outer layer 5 is made of a high magnetostriction amorphous magnetic layer with positive magnetostriction and the inner layer 6 is made of a non-magnetic amorphous alloy layer, the elastic deformation shown in Figs. A stress-induced axial magnetic anisotropy Kuo appears in the - direction, which forms an angle of 45° with the central axis direction of the cylinder as shown in FIG. In this case, if the magnetostriction constant is negative, the Kuo direction only changes by 90° to a 45° direction. Furthermore, when the inner and outer layers of the two-layer spiral cylinder are exchanged, the sign of Kuo is reversed. That is, Ku.

The direction changes by 90° and becomes a 45° direction with respect to the center axis of the 9 cylinder. The same can be considered in the case of a two-layer structure amorphous magnetic ribbon in which a low magnetostriction amorphous magnetic layer is used instead of a nonmagnetic amorphous alloy layer. By the way, the elastic deformation given to these spiral cylinders is limited when the pitch of the spiral is not very large.

It is obtained by winding and fixing the inner surface of the spiral cylinder around the outer circumferential surface of a round bar having an outer diameter equal to but slightly larger than the inner diameter of the spiral cylinder so that the inner surface of the spiral cylinder is in complete contact with the outer circumferential surface of the rod. Therefore,
If the above-mentioned two-layer structure consisting of the two layers 75j having different magnetic properties is removed by a method such as amorphous heat treatment, these two spiral cylinders can be simply wound tightly around the outer periphery of the torque transmission shaft and fixed. Thus, each of the two-layered amorphous magnetic ribbons has a torque transmission axis suitable for the construction of a torque sensor and uniaxial magnetic anisotropy in the 45° and -45° directions, respectively. In these two-layer structure amorphous magnetic ribbons, the non-magnetic layer and the low magnetostriction layer simply serve as supporting materials that take on the screw moment generated in the inner part of the ribbon. Also as a support material.

Uniaxial magnetic anisotropy as shown in FIG. 3 can also be obtained by using an amorphous magnetic ribbon with a two-layer structure consisting of a magnetic gold layer.

In this case, the signs of the magnetostrictive properties are opposite to each other, and the signs of the distribution of principal stress are also opposite to each other in the outer layer 5 and the inner layer 6, so the directions of stress induction and axial magnetic anisotropy are the same, and the overall direction is the same. As a result, uniaxial magnetic anisotropy as shown in FIG. 3 can be obtained.

FIG. 4 shows one embodiment of the present invention. Two-layered amorphous magnetic ribbons 9a and 9b with different helical directions are fixed on the outer peripheral surface of the torque transmission shaft 8 by adhesive, and the difference in magnetic permeability of the two ribbons due to the applied torque is applied to an alternating current bias magnetic field. To detect by.

It consists of an excitation winding 10, an excitation AC power supply 11, detection windings 12a and 12b connected in anti-series, and a synchronous rectification circuit 13 for obtaining a DC voltage from the detection winding induced voltage.

Here, the excitation winding 10 and the detection windings 12a and 12b are shown in the simplified representation of the windings in FIG. It is a characteristic.

In this experiment, the two-layer helical cylinder was fabricated by bonding two helical cylinders of the same shape made using two types of amorphous magnetic ribbons.

However, how to obtain this two-layer spiral Akita cylinder?

The method is not limited to the adhesive method described above.

Graph 16 in Figure 6 shows the magnetostriction constant λ8 = 24 x 10
Graph 17 shows the results when a high magnetostriction amorphous magnetic ribbon of -6 is used for the outer layer 5 and a non-magnetic amorphous alloy ribbon is used for the inner layer 6. 6. Out of the two results of 0 or more, which are the results when zero magnetostrictive amorphous magnetic ribbon is used, 1. The torque sensor according to the present invention has linearity.

It can be seen that both sensitivity and characteristics are sufficient for practical applications.

In addition to this embodiment, there is also a torque sensor that uses a magnetic head to detect changes in magnetic permeability of a two-layered amorphous magnetic ribbon. But it is possible.

[Brief explanation of drawings]

Figure 1 shows the explanation of stress induction and axial magnetic anisotropy caused by elastic deformation when the outer layer 5 in the diagram is a high magnetostrictive amorphous magnetic layer with a positive magnetostriction constant. FIG. 4 shows one embodiment of the present invention. Figure 5 shows a simplified representation of windings. FIG. 6 shows the rotational torque detection characteristics when the present invention is realized by the embodiment shown in FIG. 1. 2. A spiral cylinder made of short elastic ribbons; 2. Screw moment, 7. Cylinder after elastic deformation made of two-layered amorphous magnetic ribbon,
8. Torque transmission shaft, 9. Two-layer structure amorphous magnetic ribbon, 14. ) A cylindrical winding that shares a central axis with the torque transmission axis, 151 Simplified diagram of a cylindrical winding. Patent applicant Kosuke Harada and 2 others (a) (b) Fig. 1 Fig. 2 Fig. 3 Fig. 4 Rotating torque (N-m) Fig. 6

Claims (1)

[Claims] A high magnetostrictive amorphous magnetic ribbon A that has been deformed into a spiral cylindrical shape and has stress removed is joined with a supporting material B made of an elastic ribbon with different magnetic properties from A. A torque sensor made of a two-layered amorphous magnetic ribbon that is wound and fixed so that the inner surface of C is in close contact with the outer circumferential surface, and enables torque detection by utilizing the change in magnetic permeability of A due to the torque applied to D. .