JPH067305Y2 - Displacement detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention relates to a displacement detection device that detects a mechanical displacement of an object or a displacement of a liquid surface by using a magnetostriction phenomenon.

Conventional technology and its problems Conventionally, various types of displacement detection devices, such as a differential transformer, a potentiometer, and a capacitance type displacement detector, are known to detect mechanical displacement of an object or displacement of a liquid surface. Among them, the displacement detection device applying the magnetostriction phenomenon is particularly excellent in linearity and resolution.

As such a magnetostrictive displacement detection device, the applicant has a shape in which the permanent magnet surrounds the magnetostrictive line and has an axis line of the magnetostrictive line so that highly accurate detection can be performed even if the positional relationship of the movable permanent magnet with respect to the magnetostrictive line changes. One that is polarized in the direction is proposed (Japanese Patent Laid-Open No. 61-112923). This displacement detection device has a pulse generator that supplies a current pulse to one end of the magnetostrictive line, and a strain detection device that receives an ultrasonic wave that propagates through the magnetostrictive line. By measuring the time until the ultrasonic wave is received, the mechanical displacement given to the permanent magnet is detected.

By the way, in the above displacement detection device, in order to absorb and attenuate mechanical vibrations and shocks from the outside and prevent unnecessary disturbance from being detected by the strain detection device, the magnetostriction is applied at both ends of the middle cylinder that encloses the magnetostrictive wire. Both ends of the wire are crimped and supported via elastic rubber, and this middle cylinder is inserted into the outer cylinder to form a double cylinder structure, and a vibration absorbing material such as sponge is placed in the annular space between the outer cylinder and the middle cylinder. is doing. However, in this structure, the magnetostrictive wire is only supported by the middle cylinder at both ends, so the magnetostrictive wire vibrates like a kind of string due to external vibration or shock, and this causes an ultrasonic signal to malfunction. May occur.

The purpose of the present invention is to solve the above-mentioned conventional problems. The purpose of the present invention is to prevent the magnetostrictive wire from vibrating like a string inside the outer cylinder and to have a displacement that is excellent in assembling. It is to provide a detection device.

In order to achieve the above-mentioned object, the present invention generates an ultrasonic wave at a portion of a magnetostrictive line adjacent to a permanent magnet movable along the magnetostrictive line by causing a current pulse to flow through the magnetostrictive line, thereby causing magnetostriction. An apparatus for detecting a mechanical displacement applied to a permanent magnet by measuring a propagation time of an ultrasonic wave to a specific portion of a wire, an outer cylinder made of a non-magnetic material enclosing the magnetostrictive wire, and an outer cylinder for the magnetostrictive wire. A supporter made of elastic rubber for holding it in the center of the outer cylinder, one or more openings into which the supporter can be inserted in the middle part of the outer cylinder, and the outer periphery into which the magnetostrictive wire can be inserted into the supporter. A kerf extending from the central part to the central part is provided.

That is, since the middle portion of the magnetostrictive wire is supported by the rubber supporter for holding the central portion of the outer cylinder, it is possible to suppress the magnetostrictive wire from vibrating like a string due to external vibration or impact,
Malfunctions can be prevented. This also means that the measurement length of the magnetostrictive line can be extended by disposing the supporter. Also, since the supporter can be installed from the opening provided in the outer cylinder in a direction orthogonal to the axis line with respect to the magnetostrictive line, it can be installed after the magnetostrictive line is stretched, resulting in good workability and supporter Does not cause misalignment with respect to the magnetostrictive line.

Description of Embodiments FIG. 1 shows a specific example of a displacement detecting device according to the present invention.

In the drawing, the magnetostrictive wire 1 is inserted into a non-magnetic and conductive outer cylinder 12, and the left end portion of the outer cylinder 12 is fitted into a coil holder 13 and fixed by a set screw 14. The outer cylinder 12 has a function as a protective cylinder for the magnetostrictive wire 1 and a function as a return conducting wire for the current pulse supplied to the magnetostrictive wire 1. The outer cylinder 12 may be made of non-metal, but in this case, a return conductor for the current pulse needs to be separately provided. A ring-shaped movable permanent magnet 2 is slidably inserted into the outer circumference of the outer cylinder 12.
The opposite poles are magnetized on both sides.

Two torsion elastic wave receiving coils 15 and 16 are fixed inside the coil holder 13, and the coils 15 and 16 are the magnetostrictive wires 1 described above.
Is inserted in a non-contact state with respect to. Although only one receiving coil may be provided, if the output signals of the two coils are differentially amplified as described above, it is possible to reduce the number of nozzles that commonly enter both coils. An eccentric permanent magnet 17 is obliquely fixed near the coils 15 and 16, and the eccentric magnetic field substantially coincides with the direction of magnetic change due to a torsional elastic wave (transverse wave) propagating in the magnetostrictive line 1. Incidentally, the concrete fixing method of the odd permanent magnet 17 determines the direction in which the signal due to the transverse wave is maximized and the signal due to the longitudinal wave is minimized while actually rotating the odd permanent magnet 17. The biased permanent magnet 17 is fixed to the coil holder 13 by applying the adhesive material 18 in this direction.

Two rubber plates 19 and 20 and a pressing plate 21 are arranged at the left end of the coil holder 13, and the pressing plate 21 is fastened to the coil holder 13 with a tightening screw 22 with the rubber plates 19 and 20 sandwiched therebetween. Thereby, the magnetostrictive wire 1 is pressure-bonded and fixed between the rubber plates 19 and 20. Since the left end of the magnetostrictive wire 1 is pressure-bonded and supported by the rubber plates 19 and 20, the reflection of ultrasonic waves can be reduced. In order to prevent the magnetostrictive wire 1 from coming off from the rubber plates 19 and 20, a stopper 23 welded or soldered is arranged at the left end of the magnetostrictive wire 1, and the stopper 23 or the left end of the magnetostrictive wire 1 is disposed. A current pulse is supplied from a pulse generator (not shown).

The right end of the magnetostrictive wire 1 penetrates a spring holder 24 fitted and fixed to the right end of the outer cylinder 12, and the inside of the spring holder 24 is fixed to a slidable spring receiving plate 25 by welding or soldering. Has been done. A spring 26 is arranged in a compressed state between the spring receiving plate 25 and the spring holder 24, so that the magnetostrictive wire 1 is given a rightward tension. The function of the spring 26 is not only to give an appropriate tension to the magnetostrictive wire 1, but also when the outer cylinder 12 and the magnetostrictive wire 1 expand and contract due to ambient temperature change.
It can also prevent loosening. A damping material 27 such as adhesive rubber is applied near the right end of the magnetostrictive wire 1 to absorb the reflection of ultrasonic waves from the right end of the magnetostrictive wire 1.

A plurality of supporters 28 are arranged between the magnetostrictive wire 1 and the outer cylinder 12 at appropriate distances. As shown in FIGS. 2 and 3, the supporter 28 is integrally formed of elastic rubber, and has a cylindrical outer peripheral portion 28a which is in close contact with the inner peripheral surface of the outer cylinder 12,
It has a thin intermediate film portion 28b continuous inside the outer peripheral portion 28a, a small hole 28c for holding the magnetostrictive line 1 is formed at the center of the intermediate film portion 28b, and the small hole 28c is formed from the outer peripheral portion 28a to the above small hole 28c. A cut groove 28d reaching to is formed. And the above supporters 2
8 is inserted from the opening 12a of the outer cylinder 12 in a state where the magnetostrictive wire 1 is stretched, and is incorporated into the outer cylinder 12 by inserting the cut groove 28d into the magnetostrictive wire 1.

By adding the supporter 28 as described above, the magnetostrictive wire 1 is held in the central portion of the outer cylinder 12, and it is possible to prevent vibration such as a string due to external vibration or shock, and prevent malfunction. Further, since the contact length between the supporter 28 and the magnetostrictive wire 1 is short, the torsional elastic wave propagating on the magnetostrictive wire 1 is not unnecessarily attenuated, while the propagation of disturbance to the magnetostrictive wire 1 is suppressed. You can Further, since the supporter 28 is incorporated in the magnetostrictive wire 1 through the opening 12a of the outer cylinder 12 in the direction orthogonal to the axis, the supporter 28 is inserted in the magnetostrictive wire 1 in the axial direction, as compared with the case where the supporter 28 is inserted in the axial direction. Since the supporter 28 can be installed after the tension is set, the workability is good, and there is a problem that the supporter 28 is misaligned with respect to the magnetostrictive wire 1 or an unnecessary load acts on the magnetostrictive wire 1 in the assembled state. Absent.

The present invention is not limited to the structure of the above embodiment,
Any displacement detection device having a structure in which the magnetostrictive wire is externally enclosed is applicable. For example, in the above embodiment, a ring-shaped permanent magnet with opposite poles magnetized on both sides was used as the movable permanent magnet.
It is not limited to this. Further, in the above-mentioned embodiment, the receiving coil and the odd permanent magnet are provided in order to detect only the torsional elastic wave in a non-contact manner.
As described in Japanese Patent No. 112923, a contact-type strain sensing device may be used in which a contact is made to contact so as to be substantially orthogonal to the magnetostrictive line, and a piezoelectric element is fixed to the end of this contact.

Effect of the Invention As is apparent from the above description, according to the present invention, the middle portion of the magnetostrictive wire is supported inside the outer cylinder via the rubber supporter, so that the magnetostrictive wire looks like a string due to external vibration or shock. Vibration can be prevented, and malfunction can be prevented. Further, since the supporter is installed from the opening provided in the outer cylinder from the direction orthogonal to the axis with respect to the magnetostrictive line, the supporter can be installed after the magnetostrictive line is stretched, the workability is improved, and the supporter is improved. Does not cause misalignment with respect to the magnetostrictive line.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of a displacement detecting device according to the present invention,
FIG. 2 is a perspective view of the main part, and FIG. 3 is an enlarged sectional view of the supporter. 1 ... Magnetostrictive wire, 2 ... Permanent magnet, 12 Outer cylinder, 12a ... Opening part, 13
... Coil holder, 15, 16 ... Receiving coil, 17 ... Uneven permanent magnet, 26 ... Spring, 28 ... Supporter, 28a ... Outer peripheral part, 28b ... Intermediate film part, 28c ... Small hole, 28d ... Cut groove.

Claims (2)

[Scope of utility model registration request] 1. A current pulse is applied to a magnetostrictive line to generate an ultrasonic wave at a portion of the magnetostrictive line which is adjacent to a permanent magnet movable along the magnetostrictive line and propagates the ultrasonic wave to a specific part of the magnetostrictive line. In a device for detecting mechanical displacement applied to a permanent magnet by measuring time, an outer cylinder made of a non-magnetic material that encloses the magnetostrictive wire and an elastic rubber for holding the magnetostrictive wire in the center of the outer cylinder. 1 or 2 which has a supporter consisting of
A displacement detecting device, characterized in that the above-mentioned opening is provided, and the supporter is provided with a kerf from the outer peripheral portion into which the magnetostrictive wire can be inserted to the central portion. 2. The supporter has a cylindrical outer peripheral portion that is in close contact with the inner peripheral surface of the outer cylinder, and a thin intermediate film portion that is continuous inside the outer peripheral portion. The displacement detecting device according to claim 1, wherein a cut groove extending to the center is formed.