JP3478124B2 - Sensor couplant holding device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact medium holding device for a sensor, and more particularly to a contact medium holding device suitable for ultrasonic elements used in an AE (Acoustic Emission) method.

[0002]

2. Description of the Related Art As a method of nondestructively detecting welded joints of metal pipes, cracks of concrete members, and hollow defects existing in the material, a method of emitting sound waves or ultrasonic waves and receiving reflections thereof. Is known, and such an acoustic emission method is also used for, for example, a fish finder and ultrasonic examination of a living body.

In such an acoustic emission method, an ultrasonic sensor using piezoelectric ceramics such as PZT is generally adopted. When measuring with an ultrasonic sensor, the sensor is brought into contact with an object to be measured to emit and receive ultrasonic waves.

In this case, if a foreign substance is present between the ultrasonic sensor and the object to be measured, the measurement accuracy will decrease, so
Prevents deterioration of measurement accuracy by interposing uniform and homogeneous contact media such as water, oil, glycerin, etc. between the ultrasonic sensor and the object to be measured and pressing these contact media with the ultrasonic sensor. is doing.

However, in such a measuring method,
There was a technical problem described below.

[0006]

That is, in the conventional measurement, the contact medium was applied by coating it on the surface of the object to be measured. Each time the thickness is measured,
Accurate measurement is difficult.

Further, for example, when measuring cracks and cavity defects in metal pipes and concrete members, measurement is made on a long straight line or plane. In such measurement, contact medium such as water, oil, glycerin, etc. is used. When you apply
Since the couplant may evaporate or may deteriorate, it is difficult to perform continuous measurement with high accuracy.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a contact for a sensor which can achieve a great improvement in measurement accuracy even when continuous measurement is performed. It is to provide a device for holding a medium.

[0009]

In order to achieve the above object, the present invention is a device for holding a contact medium interposed between a sensor body and an object to be measured, wherein the sensor body is held at a central portion. An inner cylinder part, an outer cylinder part arranged at a predetermined distance from the outer periphery of the inner cylinder part, a storage part for the couplant medium provided between the inner and outer cylinder parts, and the outer cylinder. An annular gap holding portion that is provided on the outer peripheral edge of the tip of the portion to hold the couplant, and the gap holding portion is the outer tubular portion.
And a plurality of spacers protruding from the outer peripheral edge of the
And an annular resin brush provided on the inner peripheral side of the sensor,
The accommodating portion and the inner peripheral side of the space retaining portion are communicated with each other.
According to the contact medium holding device for a sensor configured as described above, the measurement can be performed by simply bringing the holding device into contact with the object to be measured, and the troublesome application work of the contact medium is unnecessary, and the handleability is improved. Improve dramatically. Further, according to the couplant holding device of the present invention, the thickness of the couplant to be interposed between the sensor body and the object to be measured is determined by the protrusion amount of the spacing member, and the couplant having a constant thickness is always provided in the sensor body. It is possible to perform the measurement while being interposed between the measurement object and the measurement object. Then, when measuring a long straight line or surface, if a part of the contact medium escapes from the space holding unit, the space holding unit and the storage unit are in communication with each other, so that the contact medium in the storage unit is sequentially replenished. It Furthermore, the space holding part is an outer cylinder part.
And a plurality of spacers protruding from the outer peripheral edge of the
And an annular resin brush provided on the inner peripheral side of the
Therefore, a plurality of spacers protrudingly fixed to the outer peripheral edge of the outer cylinder portion maintain a space between the sensor body and the object to be measured, and an annular resin brush provided on the inner peripheral side of the spacer. This makes it possible to limit the amount of the couplant that escapes to the outside. The sensor body may be an ultrasonic element, and the contact medium may be a gel contact medium in which a water-absorbing polymer is mixed with degassed water or saline. According to this configuration, the gel contact medium in which the water-absorbing polymer is mixed with degassed water or saline has a very small release of water once retained, and thus can be used for a long period of time. Further, since deaerated water or saline is used as the water content, there are no bubbles that reflect ultrasonic waves in the gel contact medium, and the measurement accuracy is improved. The sensor body may be composed of a polymeric piezoelectric film. According to this configuration, when a solid piezoelectric element such as PZT is used, a thick wave receiving plate is provided on the front side of the element, so that the measurement accuracy is lowered, but when a polymer piezoelectric film is used, such a thick wave receiving plate is used. The plate is not required, and the measurement accuracy is improved.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. 1 to 3 show an embodiment of a couplant for holding a sensor according to the present invention.

The holding device shown in the figure illustrates the case where the present invention is applied to the ultrasonic sensor 10, and includes an inner cylinder 12 and an outer cylinder 14 having a double cylindrical structure. The ultrasonic sensor 10 is a sensor body 10a whose details are shown in FIG.
And a sensor holder 1 for holding the sensor body 10a
0b and 0b.

The sensor body 10a comprises a protective film 100a made of polyester provided at the lower end, a polymeric piezoelectric film 101a made of polyvinylidene fluoride provided on the protective film, and a porous film provided on the piezoelectric film 101a. It has a plate 102a made of high quality cast iron and a low repulsion elastic rubber material 103a provided on the plate 102a, and all of these members are embedded in a resin layer 104a such as an epoxy resin, and the whole is substantially cylindrical. It is formed into a shape.

A pair of electrode plates 106a is provided on both sides of the polymeric piezoelectric film 101a, and a lead wire 105a is connected to each electrode plate 106a. The sensor holder 10b is fixed to the upper end side of the sensor body 10a and has a cylindrical shape having a diameter slightly larger than the outer diameter of the sensor body 10a.

A screw portion 100b is engraved on the outer peripheral surface of the sensor holder 10b. Incidentally, reference numeral 10 in FIG.
The member indicated by c is a sleeve 10c embedded in the sensor holder 10b, and the lead wire 105a of the sensor body 10a is inserted into the sleeve 10c.

The inner cylinder 12 is formed in a cylindrical shape with both ends open, and a screw portion 16 is provided around the inner peripheral surface. The screw portion 16 has a screw of a sensor holder 10b holding a sensor body 10a. The part 100b is screwed.

A sensor body 10a screwed to the inner cylinder 12
Is adjusted to a position where the tip of the sensor body 10a slightly projects downward from the lower end of the inner cylinder 12 by adjusting the screwing amounts of the screw portions 16 and 100b.

The outer cylinder 14 is provided at a predetermined distance from the outer peripheral surface of the inner cylinder 12, has an upper end opened, and a ring-shaped inner flange portion 18 protruding inward at the lower end. A through hole 20 is formed in the center of the inner flange portion 18, and the inner cylinder 12 is inserted into the through hole 20 at the front end side so that the inner flange portion 18 and the lower end edge are substantially flush with each other. It is fixed so that.

An annular space defined between the outer peripheral surface of the inner cylinder 12 and the inner peripheral surface of the outer cylinder 14 serves as a storage portion 22 for the couplant B. In the case of this embodiment, the contact medium B
Is a gel-like contact medium in which water-absorbing polymer is mixed with degassed water or saline.

When such a contact medium B is used, a gel-type contact medium obtained by mixing water-absorbing polymer with degassed water or saline has very little release of water once held, and therefore can be used for a long period of time. it can.

Further, since deaerated water or saline is used as the water content, there are no bubbles that reflect ultrasonic waves in the gel contact medium, and the measurement accuracy is improved.

On the outer peripheral edge of the tip of the outer cylinder 14, a contact medium B interposed between the ultrasonic sensor 10 and the object A to be measured.
Is provided with a space holding portion 24.

The spacing member 24 of this embodiment is composed of a plurality of spacers 24a and an annular resin brush 24b. The plurality of spacers 24a are fixed to the outer peripheral surface of the outer cylinder 14 so that the lower ends thereof project downward.

The lower ends of the spacers 24a are in contact with the upper surface of the object A to be measured, and by this contact, the space between the sensor body 10a and the object A to be measured is maintained. .

This interval is, for example, 0.1 to 0.5 mm.
The degree is appropriate, and can be changed by adjusting the screwing amounts of the sensor holder 10b and the screw portions 16 and 100b of the inner cylinder 12.

The annular resin brush 24b is the spacer 24.
It is arranged on the inner peripheral side of a, and the upper end side thereof is planted and fixed to the lower end surface of the inner flange portion 18 of the outer cylinder 14. The annular resin brush 24b limits the amount of the contact medium B, which is interposed between the ultrasonic sensor 10 and the object A to be measured, to escape to the outside.

The space surrounded by the annular brush 24b and the housing portion 22 are made to communicate with each other by a plurality of communication holes 26 formed through the inner flange portion 18 of the outer cylinder 14. Storage 22
A ring-shaped pressing plate 28 is placed on the upper surface of the contact medium B housed inside.

The pressing plate 28 is urged downward by a spring member 32 interposed between the pressing plate 28 and a cap 30 mounted on the upper end of the outer cylinder 14.

The biasing force of the spring member 32 is applied to the contact medium B stored in the storage portion 22 via the pressing plate 28, whereby the contact medium B is pressed downward. It is always acting, and this urging force is the pressurization of the contact medium B.

Therefore, when a part of the contact medium B interposed between the ultrasonic sensor 10 and the object A to be measured escapes to the outside, the contact medium B under pressurization immediately passes through the communication hole 26. Will be replenished via.

According to the holding device for the contact medium B configured as described above, the measurement can be performed by simply bringing the holding device into contact with the object A to be measured, and the troublesome contact medium B is required.
The application work of is not required, and the handling is dramatically improved.

Further, according to the couplant holding device of the present invention, the sensor main body 10 is controlled by the protrusion amount of the space holding portion 24.
The thickness of the contact medium B interposed between a and the object A to be measured is determined, and the measurement can be performed with the contact medium B having a constant thickness always interposed between the sensor body 10a and the object A to be measured. Therefore, variations in measurement are extremely reduced, and measurement accuracy is improved.

When measuring a long straight line or surface, if the contact medium B escapes from the space holding unit 24, the space holding unit 24 and the storage unit 22 communicate with each other. The contact medium B is replenished, and long-term measurement can be performed accurately.

Further, in the case of this embodiment, since the sensor body 10a is composed of the polymer piezoelectric film 102a, when a solid piezoelectric element such as PZT is used, a thick wave receiving plate is provided on the front side of the element. Since the measurement accuracy is lowered because it is provided, when the polymer piezoelectric film 102a is used, such a thick wave receiving plate is not necessary, and the measurement accuracy is further improved.

In the above embodiment, the case where the contact medium B is a gel contact medium in which water-absorbing polymer is mixed with degassed water or saline is exemplified, but the practice of the present invention is not limited to this. However, a homogeneous substance such as oil having high viscosity can also be used.

Further, in the above embodiment, the sensor body 10
Although the case where the polymer piezoelectric film 102a is used is illustrated in a, the implementation of the present invention is not limited to this, and a solid-state ultrasonic sensor may be used.

Further, in the above-mentioned embodiment, the space holding portion 24
The spacer 24a and the annular resin brush 24b are illustrated as an example, but the spacer 24a may be integrally provided on the outer circumference of the outer cylinder 14, or the spacer 24a and the annular resin brush 24b may be replaced by rubber or the like. The same function can be obtained by projecting and fixing the flexible annular member on the lower surface of the inner flange portion 18 of the outer cylinder 14.

[0037]

As described above in detail in the embodiments,
According to the couplant holding device for a sensor of the present invention,
The handling at the time of measurement is dramatically improved, and long-term continuous measurement can be performed with high accuracy.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of a contact medium holding device for a sensor according to the present invention.

FIG. 2 is a cross-sectional view of a main part of FIG.

3 is an explanatory diagram showing an example of a sensor used in the holding device of FIG. 1. FIG.

[Explanation of symbols]

10 Ultrasonic sensor 10a sensor body 102a Polymer piezoelectric sensor 10b sensor holder 12 inner cylinder 14 outer cylinder 16 screw part 18 Inner flange 22 Storage 24 Interval holding part 24a spacer 24b annular resin brush A Object to be measured B contact medium

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Claims (3)

(57) [Claims] 1. A holding device for a couplant, which is interposed between a sensor body and an object to be measured, wherein an inner cylinder portion for holding the sensor body at a central portion, and an outer periphery of the inner cylinder portion are arranged at a predetermined distance. An outer cylindrical portion arranged at a distance from each other, a housing portion for the couplant provided between the inner and outer cylindrical portions, and an annular shape protruding from the outer peripheral edge of the tip of the outer cylindrical portion to hold the couplant. And an interval holding part, wherein the interval holding part is projectingly fixed to an outer peripheral edge of the outer cylinder part.
A plurality of spacers and are provided on the inner peripheral side of the spacers.
A contact medium holding device for a sensor , comprising: an annular resin brush, and the storage portion and the inner peripheral side of the space holding portion are communicated with each other. 2. The sensor body is an ultrasonic element.
The contact medium is water or degassed water-absorbing polymer.
Is a gel-like contact medium mixed with saline solution.
The couplant holding device for a sensor according to claim 1. 3. The sensor body is a polymer piezoelectric film.
The cell according to claim 1 or 2, characterized in that
Medium holding device for sensors.