JPH0310047B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a magnetostrictive potentiometer that utilizes ultrasonic waves.

[Prior art]

A magnetostrictive potentiometer using ultrasonic waves was developed by the applicant of this application, and the developed technology is disclosed in Japanese Patent Application No. 53-22281 (Japanese Unexamined Patent Publication No. 54-115172) and Japanese Patent Application No. 53-22282 ( Many applications have been filed such as Japanese Patent Application Laid-Open No. 115173/1989, and Yokogawa New Technology Report '79P3
(1979) and others, and is already well known. Such a known magnetostrictive potentiometer is shown in FIG.

In FIG. 1, 10 is a magnetostrictive wire, 20 is a movable drive unit composed of an ultrasonic generation coil 21 and a permanent magnet 22, and 30 and 40 are detection coils 31 and 41 and permanent magnets 32 and 42, respectively. This is a detection unit consisting of. The detection units 30 and 40 are fixed to both ends of the magnetostrictive wire 10 and receive ultrasonic signals generated by the drive unit 20 and propagated through the magnetostrictive wire 10. The displacement position of the drive unit 20 is such that the ultrasonic signal is detected by the detection units 30 and 4.
It is obtained by detecting the difference in time until it reaches 0. The device of FIG. 1 having such a configuration is suitable for use as a non-contact potentiometer, for example, as a position return element of a recorder.

When attaching the magnetostrictive wire 10 used in the magnetostrictive potentiometer having such a configuration to a fixed member, if the magnetostrictive wire 10 is supported at other than both ends, the output will attenuate and an error will occur. Therefore, the first
In the illustrated potentiometer, the magnetostrictive wire 10 is supported by detecting sections 30 and 40 fixed to both ends thereof. On the other hand, as the magnetostrictive wire 10, a thin material such as a thin pipe or a thin ribbon is more suitable than a thick material because the influence of eddy current loss or propagation attenuation is smaller. However, the above-mentioned method of supporting both ends cannot support magnetostrictive wires that are thin and have extremely low strength, and furthermore, there are problems such as the inability to support magnetostrictive wires having shapes other than round, equilinear shapes.

[Object of the present invention]

The present invention has been made to improve these problems, and is capable of supporting magnetostrictive wires that are thin and have shapes other than straight lines, such as round magnetostrictive wires, without affecting the signal. The purpose of this invention is to obtain a magnetostrictive potentiometer with a simple overall configuration that can be used. Examples of the present invention will be described in detail below.

〔Example〕

FIG. 2 is a configuration diagram of an embodiment of the magnetostrictive potentiometer according to the present invention. In Figure 2, 10
is a magnetostrictive wire, and this magnetostrictive wire has a round shape. 2
0 is a support part that supports the magnetostrictive wire 10, and this support part is formed in a round shape along the outer periphery of the magnetostrictive wire 10 with a constant gap therebetween. 31 to 34 are the magnetostrictive wire 10 and the support part 20, respectively.
It is the connecting part that connects the two. The magnetostrictive wire 10, the supporting part 20, and the connecting parts 31 to 34 are made of Ni, for example.
It is formed by etching a metal plate with large magnetostrictive properties such as . Since the connecting portions 31 to 34 are formed by etching in this manner, according to the present invention, these connecting portions can be formed extremely thin (0.1 mm to 0.2 mm in the embodiment). The support portion 20 has its peripheral surface attached to a fixing member (not shown). Reference numeral 40 denotes a drive unit having a coil 41 (and a permanent magnet 42 shown in FIG. 1) for generating ultrasonic waves. This drive section is fixedly attached to one end 11 of the magnetostrictive wire 10. 50 is a rotating shaft, 60 is a mounting member, and 70 is a detection section. The detection unit 70 is attached to the rotating shaft 50 via an attachment member 60.

In the detection unit 70, 71 and 72 are cores, respectively.
73 is a permanent magnet. A detection coil 74 for detecting ultrasonic waves is wound around the core 71 . core 7
1 and 72 are assembled in a U-shape with a permanent magnet 73 in between, thereby forming a detection head.

The detection unit 70 having such a configuration is attached to the rotating shaft 50 via the attachment member 60 so that the magnetostrictive wire 10 is inserted into the detection head with one side open. When the rotating shaft 50 is rotated, the detecting section 70 rotates in an arc shape along the magnetostrictive line 10 about this rotating shaft.

In the magnetostrictive potentiometer having such a configuration, the ultrasonic generation coil 41 that constitutes the drive unit 40
When a pulse current is supplied to the magnetostrictive wire 10 in the coil 41, a local change in the magnetic field occurs in the magnetostrictive wire 10, and this change is converted into a longitudinal elastic wave (ultrasonic wave) by the magnetostrictive effect, and the inside of the magnetostrictive wire 10 is transmitted to the detection unit 70. propagate towards.
On the other hand, in the detection head constituting the detection section 70, a magnetic path is formed in which the magnetic flux generated by the permanent magnet 73 returns to the permanent magnet 73 through the core 71→magnetostrictive wire 10→core 72. When a magnetostrictive signal enters such a magnetic path, the permeance of the magnetic path changes due to the inverse magnetostrictive effect, causing a change in magnetic flux, and as a result, a pulse is generated in the detection coil 74 after a time corresponding to the displacement position of the detection unit 70. Voltage is generated.

Here, after applying a pulse current to the ultrasonic generation coil 41 that constitutes the drive section 40, the detection section 70
The time until the detection pulse signal is generated is the time t1, t2 required for the detection unit 70 to detect the direct wave from the coil 41 and the reflected wave reflected from the end face 12 of the magnetostrictive wire 10 and returned. By measuring,
The displacement position of the detection section 70, which is a movable section, can be detected. Equation (1) below shows the calculation contents of t1 and t2, and by performing such calculations, it is possible to obtain a displacement position signal from which the influence of temperature changes and the like on the speed of sound has been removed.

(t2-t1)/(t2+t1) =d2/(d1+d2)...(1) Here, t1=d1/c t2=d2/c d1=distance from the drive section 40 to the detection section 70 d2=detection section 70 and the distance C to the end face 12 of the magnetostrictive wire 10 = speed of sound. That is, the ratio of the sum and difference of the delay times t1 and t2 becomes a signal representing the displacement position of the detection section 70, which is a movable section.

In the magnetostrictive potentiometer according to the present invention having such a configuration, the connecting portions 31 to 34 are integrally molded together with the magnetostrictive wire 10 and the support portion 20 by etching.
4 can be configured extremely thin as in the embodiment. As a result, according to the present invention, it is possible to obtain a magnetostrictive potentiometer having the support portion 20 that supports the thin and weak magnetostrictive wire 10 without substantially affecting the propagating longitudinal elastic waves. Further, according to the present invention, even a round magnetostrictive wire 10 can be supported, and since the magnetostrictive wire 10 and the support part 20 are formed by integral molding, the structure is simple, and moreover, the support part 20 is used. As a result, it is possible to obtain a magnetostrictive potentiometer that is easy to attach to a device and has an inexpensive structure.

[Other Examples]

Although FIG. 2 shows an embodiment of a magnetostrictive potentiometer in which the magnetostrictive wire is made into a round shape, FIG. 3 is a configuration diagram of an embodiment of a linear magnetostrictive potentiometer in which the magnetostrictive wire is made into a straight shape. In FIG. 3, 10 is a straight magnetostrictive wire, 20 is a support part, 31...34 are connecting parts, 40 is a drive part attached to one end 11 of the magnetostrictive wire 10, and 70 is a displaceable detection part. It is. In the potentiometer of FIG. 3 having such a configuration, a linear magnetostrictive potentiometer having the same effect as that of FIG. 2 can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional magnetostrictive potentiometer, and FIGS. 2 and 3 are block diagrams showing embodiments of the magnetostrictive potentiometer according to the present invention. 10... Magnetostrictive wire, 20... Support part, 31-34
... Connecting section, 40 ... Drive section, 70 ... Detection section.

Claims (1)

[Claims] 1. A magnetostrictive wire that is connected to a support part attached to a fixed member via a plurality of connecting parts and formed by integrally molding a magnetostrictive material together with the support part by etching, and is attached to one end of this magnetostrictive wire. A magnetostrictive potentiometer comprising: a driving section that generates a signal on the magnetostrictive wire; and a detecting section that moves along the magnetostrictive wire and detects the signal that electrolytically spreads the magnetostrictive wire.