JPH0754353B2 - Ultrasonic transducer for high temperature - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to high temperature transducers, in particular the position and shape of structures in reactor vessels filled with liquid sodium, which is an opaque substance, and various equipment in the reactor. Related to what is used to make the recognition of.

[Prior Art] FIG. 2 is a sectional view showing a conventional high temperature ultrasonic transducer. In the figure, (1) is a cylindrical box-shaped stainless steel case, (2) is a stainless steel case cover for sealing the opening of the stainless steel case (1), which is welded to the stainless steel case (1) and sealed. Is configured. (3) is a disc-shaped high-temperature ultrasonic transducer made of lithium niobate disposed on the inner surface of the bottom of the stainless steel case (1), with a Curie point of 1200 ° C and an electromechanical coupling coefficient.
Kt Is 0.17, frequency is about 2.5 MHz, and pulse width is about 50 μsec. (4) is a silver paste (8) which is a joining member fired at 800 ° C., and the high temperature ultrasonic transducer (3) is joined to the inner surface of the bottom of the stainless steel case (1). (5) is a hermetic seal connector attached through the stainless case cover (2), and (6) is an electric wire covered with a silicone rubber tube. The seal connector (5) and the ultrasonic transducer for high temperature are used. (3) is connected to.
(7) is a MI cable (Mineral Insulated Cable) connected to the seal connector (5), and (8) is a column attached to the stainless case cover (2).

The conventional high temperature ultrasonic transducer is constructed as described above, and the sealed container containing the high temperature ultrasonic transducer (3) made of lithium niobate having a Curie point of 1200 ° C. is a stainless steel case (1) and a stainless steel case cover. (2) consists of the following conditions: temperature of 200 ℃ -250 ℃, radiation 1.
Even in a reactor vessel of the order of 0 × 10 ⁶ Rad, it has corrosion resistance and can be used for a long time. Also, a stainless steel case (1) and a stainless steel case cover (2)
When a predetermined voltage is applied to the high temperature ultrasonic transducer (3) sealed by, the frequency is 2.5 MHz and the pulse width is
An ultrasonic wave of 50 μsec is oscillated, and the ultrasonic wave is transmitted to the outside of the stainless steel case (2) through the bottom of the stainless steel case (1). At this time, the directivity angle is 1.3 (-6 dB),
The S / N ratio was at most 20 dB.

[Problems to be Solved by the Invention] In the conventional high temperature ultrasonic transducer as described above, the high temperature ultrasonic transducer (3) is made of lithium niobate having a Curie point of 1200 ° C. and an electromechanical coupling coefficient of 0.17. For,
Although it is excellent in terms of temperature resistance, it has a problem that the S / N ratio is poor because the electromechanical coupling coefficient is small, the conversion efficiency between electric and ultrasonic waves is not good, and the ultrasonic energy is small.

Further, the high temperature ultrasonic transducer (3) is bonded to the inner surface of the bottom of the stainless steel case (1) with a silver paste (4) which is a bonding material, and the high temperature ultrasonic transducer (3) and the stainless steel case (1) are joined together. Since the coefficients of thermal expansion are different, a high temperature ultrasonic transducer (3) or a stainless steel case (1) caused by the temperature difference between the operating environment temperature and the storage location and repeated temperature changes
Deterioration of directivity due to warpage at the bottom of the base plate and partial or full peeling of the ultrasonic transducer (3) for high temperature from the stainless steel case (1), resulting in the ultrasonic transducer (3) for high temperature. Part or all of the generated ultrasonic energy does not propagate to the stainless steel case (1), and there is a problem in that performance deterioration such as S / N ratio deterioration, directivity angle change, and pulse width expansion occurs.

The present invention has been made to solve the above problems, and an object thereof is to obtain a high temperature ultrasonic transducer having a good S / N ratio and excellent durability without deterioration of initial performance.

[Means for Solving the Problems] A high temperature ultrasonic transducer according to the present invention includes a container made of stainless steel and a high temperature ultrasonic transducer having a large electromechanical coupling coefficient disposed on the inner surface of the bottom of the container. And a silicone oil interposed between the inner surface of the bottom portion formed on the mirror surface of the container and the container contact surface formed on the mirror surface of the high temperature ultrasonic transducer, and the high temperature ultrasonic transducer at the bottom portion of the container. The fixing member is fixed to the inner surface.

[Operation] In this invention, since the ultrasonic transducer for high temperature is formed of a material having a large electromechanical coupling coefficient, the conversion efficiency between electric and ultrasonic waves is good, and the ultrasonic energy is large. Further, since the container contact surface formed on the mirror surface of the ultrasonic transducer for high temperature is fixed to the inner surface of the bottom formed on the mirror surface of the container made of stainless steel by the fixing member via silicone oil, Even if the coefficient of thermal expansion of the ultrasonic transducer differs from that of the stainless steel case, the temperature of the operating environment and the storage location change due to the difference in the thermal expansion coefficient of both, and the bottom of the ultrasonic case for high temperature or stainless case caused by repeated temperature changes The problem of deterioration of directivity due to the warp and partial or full peeling of the ultrasonic transducer for high temperature from the stainless steel case disappeared.

[Embodiment] FIG. 1 is a sectional view showing an embodiment of the present invention. In the figure, the same configurations as those of the conventional example are denoted by the same reference numerals, and the description of the duplicated configurations will be omitted. (1) is a stainless steel case, the inner surface of the bottom of which is mirror-finished. (2) is a stainless case cover that seals the opening of the stainless case (1), and is assembled to the stainless case (1) by welding to form a sealed container. (13) is a disc-shaped high-temperature ultrasonic transducer made of lead titanate-based ceramics.
The case contact surface that is brought into contact with the inner surface of the bottom of the stainless steel case (1) is formed into a mirror surface. This high-temperature ultrasonic transducer (13) has a Curie point of 360 ° C., an electromechanical coupling coefficient of 0.45, a frequency of about 2.5 MHz, a pulse width of 20 μsec, and a thermal expansion coefficient of 6 × 10 ⁻⁶ . (14) is a disc-shaped pressing member holding plate which constitutes a part of a fixing member having a plurality of screw holes at equal intervals, and the outer peripheral edge of which is a step formed on the inner peripheral surface of the Steres case (1). It is fixed to the section with screws (9). (15) is a vibrator holding screw that constitutes a part of a fixing member that is screwed into each screw hole of the holding member holding plate (14), and (16) is screwed to the tip of the vibrator holding screw (16). and pressing pieces of stainless steel, (17) is a polyimide having flexibility, which is an insulating member, 250 ° C. of heat resistance, 10 ¹⁷
It has insulation of Ω / cm and radiation resistance of 1 × 10 ⁷ Rad order or more. (18) is a liquid silicone oil, which is used for the inner surface of the bottom of the stainless steel case (1) and the ultrasonic transducer for high temperature
It is interposed between and 3).

To attach the ultrasonic transducer for high temperature (13) to the stainless steel case (1), first apply silicone oil (18) to the inner surface of the bottom of the stainless steel case (1), and then attach the ultrasonic transducer for high temperature (13). ) Is disposed on the inner surface of the bottom of the stainless steel case (1) coated with silicone oil (18).
A polyimide sheet (17) which is a heat-resistant sheet having flexibility is placed on the surface of the high-temperature ultrasonic oscillator (13) opposite to the case contact surface. Next, the outer peripheral edge of the holding member holding plate (14) screwed with the vibrator holding screw (15) in each screw hole is screwed (9) to the step formed on the inner peripheral surface of the stainless steel case (1). Fix with. After that, each vibrator holding screw (15) is screwed, and the polyimide sheet (17) is pressed by the holding piece (16) attached to the tip of the vibrator holding screw (15). By the pressing force of 15), the high temperature ultrasonic transducer (13) is pressed and fixed to the inner surface of the bottom of the stainless steel case (1). Finally, the stainless steel case (1) is covered with the stainless steel case cover (2).
Attach by welding.

In the high-temperature ultrasonic transducer configured as described above, the high-temperature ultrasonic oscillator (13) made of lead titanate-based ceramics has a Curie point of 360 ° C and a transducer usage condition of 200 ° C to 250 ° C. Therefore, it operates normally without being affected by temperature, and the electromechanical coupling coefficient is 0.45, which is higher than the electromechanical coupling coefficient of 0.17 of the conventional high temperature ultrasonic transducer (3) made of lithium niobate. , The conversion efficiency between electric and ultrasonic waves was good, the ultrasonic energy increased and the S / N ratio improved. Further, the high temperature ultrasonic transducer (13) made of lead titanate-based ceramics has a coefficient of thermal expansion of 6 × 10 ⁻⁶ , and the stainless steel case (1) has a coefficient of thermal expansion of 16 × 10 ^−6. , It is different from the stainless steel case (1) by an order of magnitude. Therefore, when the high temperature ultrasonic transducer (15) of this embodiment is soldered to the inner surface of the bottom of the stainless steel case (1) with the silver paste (4) as in the conventional case, the high temperature ultrasonic transducer (13) is used at low temperature. ) Even if it is soldered to the stainless steel case (1), if the usage temperature is high, the ultrasonic transducer (15) for high temperature or the stainless steel case (1) will warp due to the difference in expansion coefficient between the two. The directivity deteriorates and the high-temperature ultrasonic transducer (15) is partially or wholly peeled off from the stainless steel case (1) and cannot be put to practical use. However, in this embodiment, the stainless steel case (1) is used. ) A silicone oil (18) is interposed between the inner surface of the bottom of the stainless steel case (1) and the ultrasonic vibrator (13) for high temperature, and the ultrasonic vibrator (15) for high temperature is held on the bottom of the stainless steel case (1). (4) and oscillator pressed Because it was pressed and fixed by a fixing member consisting of a screw (15), stainless steel case (1) and the high temperature ultrasonic transducer (1
Even if the coefficient of thermal expansion is significantly different from that of 3), the silicone oil (18) absorbs the warp of the ultrasonic vibrator for high temperature (13) caused by temperature changes during storage and use of the vibrator and repeated temperature changes. The problem of deterioration of directivity and peeling due to warpage caused by conventional soldering does not occur.
Therefore, the ultrasonic transducer for high temperature has excellent durability without deterioration of initial performance.

In addition, the silicone oil (18) is exposed to high temperature ultrasonic vibration (1
By interposing it between the stainless steel case (1) and the bottom of the stainless steel case (1), the sound transmission efficiency is significantly improved compared to the case where both are in direct contact, that is, an air layer is interposed, and the silver paste ( It has the same acoustic propagation efficiency as when the two are joined in 4). Also, stainless steel case (1)
Since the inner surface of the bottom of the and the case contact surface of the ultrasonic transducer for high temperature (13) are formed as mirror surfaces, the stainless steel case (1)
The layer of silicone oil (16) interposed between the bottom of the and the high temperature ultrasonic transducer (15) is extremely thin, and the sound propagation efficiency is improved. Therefore, the S / N ratio is also improved.

Furthermore, since the high-temperature ultrasonic vibrator (15) made of lead titanate-based ceramics does not have the cleavability unlike lithium niobate, it is hard to break and strong against thermal shock. Therefore, the manufacturing yield at the time of manufacturing the ultrasonic vibrator was improved and the life was improved.

In this embodiment, the high temperature ultrasonic transducer (13) is made of lead titanate-based ceramics having a Curie point of 300 ° C. or higher, but the present invention is not limited to this, and the stainless steel case (1) and the thermal expansion are used. It is needless to say that the present invention can be applied as long as the electromechanical coupling coefficient is large and the coefficient is high temperature even if the coefficients are different. For example, there is lead silicon titanate-based ceramics other than lead titanate-based ceramics. In addition, although silicone oil (18) is used to propagate sound in this embodiment, oil,
It goes without saying that even if a liquid such as a liquid metal is used, the same function as that of the silicone oil is exhibited.

EFFECTS OF THE INVENTION As described above, according to the present invention, the container contact surface formed on the mirror surface of the ultrasonic transducer for high temperature having a large electromechanical coupling coefficient is formed on the inner surface of the bottom portion formed on the mirror surface of the container formed of stainless steel. Since it is fixed by the fixing member via silicone oil, the conversion efficiency between electric and ultrasonic waves is good, the ultrasonic energy is large, and the sound propagation efficiency is improved compared to the conventional one. The N / N ratio is improved, and even if the thermal expansion coefficient of the ultrasonic transducer for high temperature differs from that of the stainless steel case, the warp of the ultrasonic transducer for high temperature or the bottom of the container caused by the temperature change during storage and use of the transducer Is absorbed by the silicone oil interposed between the inner surface of the bottom of the container and the ultrasonic transducer for high temperature, and the directivity deteriorates due to warping and the ultrasonic transducer for high temperature is partially removed from the stainless steel case. Alternatively, there is an effect that the problem of complete peeling can be solved and an ultrasonic transducer for high temperature having excellent durability without deterioration of initial performance can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view showing a conventional high temperature ultrasonic transducer. In the figure, (1) is a stainless steel case (container),
(2) is a stainless steel case cover (container), (13) is an ultrasonic vibrator for high temperature, (14) is a holding member holding plate (fixing member), (15) is a vibrator holding screw (fixing member), (17) )
Is a polyimide sheet (insulating member), and (18) is silicone oil (liquid).

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Hirokazu Karasawa 1-1-1, Shibaura, Minato-ku, Tokyo Inside Toshiba Headquarters office (72) Inventor Masuo Sato 1-1-1, Shibaura, Minato-ku, Tokyo Toshiba Headquarters Office (56) References Japanese Patent Laid-Open No. 55-46620 (JP, A) Japanese Utility Model 59-189156 (JP, U) Japanese Patent Publication No. 59-11238 (JP, B2)

Claims (2)

[Claims] 1. A container made of stainless steel, an ultrasonic vibrator for high temperature having a large electromechanical coupling coefficient disposed on the inner surface of the bottom of the container, an inner surface of the bottom formed on the mirror surface of the container and ultrasonic waves for high temperature. A high temperature characterized by comprising silicone oil interposed between a container contact surface formed on the mirror surface of the vibrator and a fixing member for fixing the high temperature ultrasonic vibrator to the inner surface of the bottom of the container. Ultrasonic transducer. 2. The high temperature ultrasonic transducer has a Curie point of 300 ° C.
The ultrasonic transducer for high temperature according to claim 1, which is the lead titanate-based ceramics described above.