JPH07311183A - Sensor for ultrasonic densitometer - Google Patents

Abstract

PURPOSE:To enhance accuracy in the measurement of sound velocity, while reducing the size, by measuring the temperature in the ultrasonic propagation region accurately. CONSTITUTION:The sensor 10 comprises a planar ultrasonic oscillator 12, a radiator 14 loaded with the ultrasonic oscillator 12 and radiating ultrasonic wave U generated therefrom, a reflector 16 disposed oppositely to the reflector 14 through a liquid L to be measured and reflecting the ultrasonic wave U radiated from the ultrasonic oscillator 12 back to the ultrasonic oscillator 12, a post 18 coupling the reflector 16 and the radiator 14 and a temperature measuring element 60 disposed in the post 18. The ultrasonic oscillator 12 is provided with a central through hole 20 and the post 18 is provided in the axial direction thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor used in, for example, an ultrasonic densitometer, and more particularly to a sensor used to know various characteristics of a liquid by measuring the velocity of ultrasonic waves propagating in the liquid. .

[0002]

2. Description of the Related Art FIG. 3 shows a conventional sensor such as an ultrasonic densitometer, FIG. 3 (1) is a vertical sectional view taken along the line III-III in FIG. 3 (2), and FIG. 3 (2) is a plan view. . Hereinafter, description will be given with reference to these drawings.

A sensor 50, such as an ultrasonic densitometer, has a plate-shaped ultrasonic vibrator 52, a radiation plate 54 for mounting the ultrasonic vibrator 52 and radiating an ultrasonic wave U generated from the ultrasonic vibrator 52. A reflecting plate 56 facing the radiation plate 54 with the liquid L to be measured sandwiched therebetween and reflecting the ultrasonic waves U radiated from the ultrasonic transducer 52 toward the ultrasonic transducer 52, and the reflecting plate 56 and the radiation plate 54. A pillar 58 for connecting the
The temperature measuring element 60 is provided inside. Then, the support column 58 is provided outside the ultrasonic transducer 52.

Next, the operation of the sensor 50 will be described.

The ultrasonic wave U generated from the ultrasonic vibrator 52
Is radiated from the radiation plate 54 to the liquid L to be measured. The ultrasonic wave U propagates through the liquid L to be measured, is reflected by the reflection plate 56, and returns to the ultrasonic transducer 52 again. Since the distance D between the reflection plate 56 and the radiation plate 54 is constant, the propagation time t from the emission of the ultrasonic wave U to the return of the ultrasonic wave U is measured, whereby the ultrasonic wave U in the liquid L to be measured is measured. Speed of sound v
(V = 2D / t) can be calculated. Then, based on the already known relationship between the sound velocity v and the concentration of the measured liquid L, the concentration of the measured liquid L corresponding to the sound velocity v is obtained.

Further, since the sound velocity v has temperature dependency, the sound velocity v is corrected by measuring the temperature T of the propagation region 62 of the ultrasonic wave U by the temperature measuring element 60. For example,
The ultrasonic wave propagation velocity of distilled water changes about 0.3 [m] per 0.1 [℃]. In this case, in order to guarantee the measurement resolution of 0.1 [m], the temperature of 0.03 [℃] must be measured accurately.

[0007]

However, the sensor 50 has the following problems.

As is clear from FIG. 3A, strictly speaking, the temperature measuring element 60 measures the temperature T outside the propagation region 62 of the ultrasonic wave U. Therefore, since the temperature T measured by the temperature measuring element 60 does not necessarily match the temperature T of the propagation region 62, the correction of the sound velocity v is insufficient and the measurement accuracy is reduced.

If the amount of the liquid L to be measured is small, the sensor 50 cannot be immersed in the liquid L to be measured, so that the sensor 50 is required to be small. However, the fact that the column 58 is provided outside the ultrasonic transducer 52 has been a factor that hinders downsizing of the sensor 50. As a result, when the sensor 50 is mounted in the pipe, the diameter of the pipe must be increased according to the size of the sensor 50, which incurs a great expense on the user of the sensor 50.

[0010]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a sensor such as an ultrasonic densitometer, which can improve the accuracy of sound velocity measurement by accurately measuring the temperature of the propagation region of ultrasonic waves and can be downsized. To provide.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and includes a plate-shaped ultrasonic vibrator, and the ultrasonic vibrator to which the ultrasonic vibrator is attached. A radiation plate that radiates the generated ultrasonic waves, and a reflection plate that faces the radiation plate while sandwiching the liquid to be measured and that reflects the ultrasonic waves radiated from the ultrasonic vibrator toward the ultrasonic vibrator, This is an improvement of a sensor such as an ultrasonic densitometer, which is provided with a support for connecting the reflection plate and the radiation plate and a temperature measuring element provided in the support.

That is, a through hole is provided in the center of the ultrasonic transducer, and the support column is provided in the axial direction of the through hole.

[0013]

The ultrasonic wave generated from the ultrasonic oscillator is radiated into the liquid to be measured through the radiation plate. The emitted ultrasonic waves are reflected by the reflector while propagating through the liquid to be measured, and then return to the ultrasonic transducer. The time from when the ultrasonic wave is emitted from the ultrasonic vibrator to when it returns to the ultrasonic vibrator represents the speed of sound of the ultrasonic wave in the liquid under measurement. because,
Since the radiation plate and the reflection plate are connected by the columns,
This is because the distance between them is always constant. On the other hand, since the speed of sound is closely related to various characteristics such as the concentration of the liquid to be measured, it is possible to know the various characteristics of the liquid to be measured by measuring the speed of sound. In addition, the speed of sound has temperature dependence. Therefore, the temperature of the liquid to be measured is measured by the temperature measuring element to correct the sound velocity. At this time, the temperature measuring element measures the temperature at the approximate center in the region where the ultrasonic waves propagate. This is because the column is provided in the axial direction of the through hole of the ultrasonic transducer and the temperature measuring element is provided in the column.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a sensor such as an ultrasonic densitometer according to the present invention. FIG.
FIG. 1 (2) is a plan view taken along line -I. Hereinafter, description will be given with reference to FIGS. 1 and 2. However, the same parts as those in FIG.

A sensor 10 such as an ultrasonic densitometer according to the present invention.
Is a plate-shaped ultrasonic vibrator 12 and the ultrasonic wave U generated by the ultrasonic vibrator 12 when the ultrasonic vibrator 12 is attached.
A radiating plate 14 for radiating light, a reflecting plate 16 facing the radiating plate 14 with the liquid L to be measured interposed therebetween, and reflecting an ultrasonic wave U radiated from the ultrasonic vibrator 12 toward the ultrasonic vibrator 12. Support 18 for connecting the reflector 16 and the radiator 14
And a temperature measuring element 60 provided in the column 18. Then, a through hole 20 is provided at the center of the ultrasonic transducer 12, and a column 18 is provided in the axial direction of the through hole 20.

The ultrasonic oscillator 12 is formed in an annular shape by, for example, a piezoelectric ceramic or the like. The temperature measuring element 60 is an element such as a thermistor whose electric resistance changes with temperature. The electrodes, wiring, etc. of the ultrasonic transducer 12 and the temperature measuring element 60 are omitted in the drawing.

FIG. 2 is a block diagram of the ultrasonic densitometer. The operation of the sensor 10 will be described below with reference to FIGS. 1 and 2. However, the same parts as those in FIG.

The ultrasonic densitometer 30 comprises a sensor 10 and a main body 3
2 and. The main body 32 includes an ultrasonic wave propagation velocity measuring unit 34 for measuring the velocity v of the ultrasonic wave U propagating in the liquid L to be measured, a temperature measuring unit 36 for measuring the temperature T of the liquid L to be measured, and an ultrasonic densitometer 30. An external input switch 38 for turning on and off, an arithmetic processing unit 40 for calculating the concentration of the liquid L to be measured based on the measurement data obtained by the ultrasonic propagation velocity measuring unit 34 and the temperature measuring unit 36, and an arithmetic processing The memory unit 42 stores software for operating the unit 40, and the output unit 44 outputs the calculation result of the arithmetic processing unit 40.

The container 46 is filled with the liquid L to be measured, and the sensor 10 is immersed in the liquid L to be measured. Here, the electric pulse generated from the ultrasonic wave propagation velocity measuring unit 34 is applied to the ultrasonic wave oscillator 12. The ultrasonic transducer 12 converts the electric pulse into an ultrasonic wave and radiates the ultrasonic wave U into the liquid L to be measured through the radiation plate 14. The ultrasonic wave U propagates through the liquid L to be measured, is reflected by the reflection plate 16, and returns to the ultrasonic vibrator 12. The ultrasonic transducer 12 converts the returned ultrasonic wave U into an electric reception signal and outputs it to the ultrasonic wave propagation velocity measuring unit 34. The ultrasonic wave propagation velocity measuring unit 34 measures the velocity v by measuring the time from the application of the electric pulse to the ultrasonic oscillator 12 to the input of the reception signal by the ultrasonic oscillator 12. A constant current is supplied to the temperature measuring element 60 from the temperature measuring unit 36. As a result, a voltage proportional to the temperature T is generated across the temperature measuring element 60. The temperature measuring unit 36 measures the temperature T by measuring this voltage.

The temperature measuring element 60 is provided in the column 18, and the column 18 is provided in the axial direction of the through hole 20. That is, the temperature measuring element 60 measures the temperature T at the almost center of the propagation region 48 of the ultrasonic wave U. Therefore, the measured temperature T is a value that is extremely averaged even if there is temperature unevenness in the propagation region 48.
Will accurately reflect the temperature of.

Further, since the supporting column 18 is provided in the axial direction of the through hole 20 of the ultrasonic transducer 12, the supporting column 18 is inside the ultrasonic transducer 12. As a result, it is possible to reduce the size of the conventional column as compared with a column in which the column is outside the ultrasonic transducer.

[0022]

According to the sensor of the present invention, by measuring the temperature at the center in the ultrasonic wave propagation region, the ultrasonic wave propagation region can be compared to the conventional temperature measurement outside the ultrasonic wave propagation region. Can measure the exact temperature of. As a result, the temperature dependence of the ultrasonic wave propagation velocity can be accurately corrected, and the measurement accuracy can be improved.

Further, since the support pillar is provided inside the ultrasonic vibrator by providing the support pillar in the axial direction of the through hole of the ultrasonic vibrator, the conventional support pillar extends outside the ultrasonic vibrator. Can be made smaller than.

[Brief description of drawings]

1 shows an embodiment of a sensor such as an ultrasonic densitometer according to the present invention, FIG. 1 (1) is a vertical sectional view taken along the line I-I in FIG. 1 (2), and FIG. 1 (2) is a plan view. Is.

2 is a block diagram of an ultrasonic densitometer configured using the sensor of FIG. 1. FIG.

FIG. 3 shows a sensor such as a conventional ultrasonic densitometer, and FIG.
(1) is a vertical sectional view taken along the line III-III in FIG.
(2) is a plan view.

[Explanation of symbols]

 10 Sensor 12 Ultrasonic Transducer 14 Radiating Plate 16 Reflecting Plate 18 Support 20 Ultrasonic Transducer Through Hole 60 Temperature Measuring Element U Ultrasonic L Liquid to be Measured

Claims (1)

[Claims] 1. A plate-shaped ultrasonic transducer, a radiation plate for mounting the ultrasonic transducer and radiating ultrasonic waves generated from the ultrasonic transducer, and a liquid to be measured sandwiched between the radiation plates. A reflecting plate that is opposed and reflects the ultrasonic waves emitted from the ultrasonic vibrator toward the ultrasonic vibrator,
In a sensor such as an ultrasonic densitometer provided with a pillar connecting the reflection plate and the radiation plate and a temperature measuring element provided in the pillar, a through hole is provided in the center of the ultrasonic transducer. A sensor such as an ultrasonic densitometer, wherein the support is provided in the axial direction of the through hole.