JPH0110574Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> The present invention is characterized in that the inner surface of the wall facing the liquid surface to be measured has a concave curved shape with respect to the liquid surface to be measured, such as a part of a spherical or cylindrical shape. , relates to a mounting structure for an ultrasonic level meter in which an ultrasonic transducer is attached to the wall side of the concave curved surface, and the distance to the liquid level to be measured is measured using ultrasonic waves.

<Prior Art> For example, in a flow meter using a Palmer bolus fluid, an ultrasonic level meter is used to measure the liquid level.

A flowmeter using a Palmer bolus flume has a cylindrical flow path 1 as shown in Figures 1 and 2.
1, a Palmer bolus furium 12 is arranged. The frium 12 is constructed by forming side walls 14 and 15 in an inverted trapezoid shape diagonally upward from both side edges of a bottom plate 13.

The flow of the fluid 16 flowing within the flow path 11 is restricted by the fluid 12, and the level of the liquid surface 17 of the fluid 16 near the inlet of the fluid 12 corresponds to the flow rate of the fluid. Therefore, by measuring the level of the liquid surface 17, the flow rate of the fluid 16 can be measured.

In order to measure the level of the liquid level 17, a hole is made in the upper part of the channel 11 facing the liquid level 17, and a cylindrical attachment part 18 is attached to the hole. Mounting part 18
Ultrasonic level meter transmitter 1 including a transducer at the upper end
9 is attached.

<Problem to be solved by the invention> In such a flowmeter, an error sometimes occurs in the measured flow rate. As a result of investigating the cause, it was found that it was based on the following reasons.

That is, as shown in FIG. 3, the ultrasonic pulse from the ultrasonic level meter transmitter 19 is incident perpendicularly to the liquid surface 17, and the reflected wave follows a path 21 shown by a solid line.
Take. However, since the ultrasonic pulse beam has a spread, there are various reflection paths 2 as shown by the dotted line.
Pass through 2. In other words, the upper side of the flow path 11, in other words, both sides of the attachment part 18 of the ultrasonic level meter transmitter 19, especially both sides in the extending direction of the flow path 11, have a concave curved surface with respect to the liquid level 17, especially the cylindrical surface. It makes up the department. The ultrasonic waves that have reached the inner surfaces of the side walls 11a and 11b reach the ultrasonic level meter transmitter 19 through the same path. This path 22 is longer than the ultrasound path 21 shown by the solid line. As mentioned above, since it is a concave curved surface, the lens action causes the things that have passed through the unnecessary path 22 to return in a concentrated manner, and the received level becomes considerably strong, resulting in an erroneous signal.

Furthermore, as shown in FIG. 4, when the fluid 16 flows in waves and the waves become larger than the wavelength of the ultrasonic waves, the ultrasonic waves that arrive perpendicular to the liquid surface 17 as shown by the solid line 23 Side wall 11 for wave front
In some cases, the reflected waves do not return to the transducer after being reflected by the inner surfaces of the side walls 11a and 11b and reach the transducer through an unnecessary path 24 as shown by the dotted line 24. In such a case, a malfunction will clearly occur. Because of the waves, reflected waves on the correct route may or may not be received, and reflected waves on unnecessary routes are also received, making the received waves unstable.

For this purpose, for example, as shown in FIGS. 5 and 6, sound absorbing materials 25 and 26 are attached to the inner surfaces of the concave curved surfaces 20 on both sides of the mounting portion 18, and the waves of the fluid 16 cause the sound to be absorbed as shown as a path 27, for example. A conceivable structure is such that the sound absorbing material 26 absorbs ultrasonic waves directed toward the concave curved surface 22.

However, with this structure, there is a risk that the fluid will come into contact with the sound absorbing materials 25, 26 when the flow rate increases, and foreign matter contained in the fluid will adhere to the sound absorbing materials 25, 26, deteriorating the sound absorbing performance of the sound absorbing materials 25, 26. There is. Therefore, during long-term use, the sound absorbing performance of the sound absorbing materials 25 and 26 deteriorates and returns to its original state.

In some cases, instead of the sound absorbing materials 25 and 26, a reflecting plate is provided at the same location to scatter the reflected ultrasonic waves that have reached the concave curved surface 20. As this reflecting plate, an uneven surface larger than the wavelength of the ultrasonic wave, that is, one having projections or recesses distributed almost uniformly is used.

An example of this is shown in FIG.
Attachment portions 18 are provided on the inner surfaces of the side walls 11a and 11b on both sides of the
Reflector plate 2 that is close to and almost forms part of a spherical surface.
The case where 8 and 29 are installed is shown.

As shown in FIG. 8, the ultrasonic level meter transmitter 1
There is also an example in which the flat reflecting plates 28 and 29 are formed so as to reach the upper edges of the side plates 14 and 15 of the frium 12 from the position of the mounting portion 18 obliquely with respect to the transmission/reception direction 33 of the frame 12 .

However, even in the examples shown in FIGS. 7 and 8, unnecessary reflected waves cannot be completely removed.
A portion of the unnecessary reflected waves enters the hole in the mounting portion 18 to which the ultrasonic kevel meter transmitter 19 is mounted, causing errors.

The present invention has been made to solve the above-mentioned problems, and its purpose is to remove unnecessary reflected waves from the liquid surface to be measured and obtain a correct liquid level value.

<Means for Solving the Problems> The present invention for solving the above problems has the following configuration.

That is, the installation of an ultrasonic level meter installed in a flow path in which a Palmer bolus frium is installed and the inner surfaces of at least both side walls of the ultrasonic transducer mounting part are concave curved surfaces relative to the liquid level to be measured. In the structure, the correct ultrasonic waves from the liquid surface to be measured are arranged opposite to the mounting part of the transducer so as to prevent the reflected ultrasonic waves from the liquid surface to be measured from being re-reflected to the transducer. An ultrasonic level characterized by having a single reflecting plate having a hole through which the sound waves pass, bent from approximately the center, and fixed on both sides to the concave curved surface of the inner surface of the side wall of the flow path. This is the mounting structure of the meter.

<Function> Unnecessary reflected waves from the liquid surface to be measured are not reflected back to the ultrasonic transducer by the reflection plate bent from approximately the center provided on the inner surface of the side wall of the channel. , only the correct reflected waves return to the ultrasound transducer.

<Example> FIG. 9 shows an embodiment of this invention.

In this example, a single reflecting plate 34 with holes is placed in the flow path 11 so as to prevent re-reflected waves from the liquid surface 17. Channel 1 on both sides in the longitudinal direction
It is bent so as to approach the concave curved surface 20 of No. 1.

That is, one reflecting plate 34 is bent from its center so that the ridgeline faces the liquid level 17, and both sides of this reflecting plate 34 are provided on the inner surface of the concavely curved side wall of the flow path 11.

Further, the size of the holes 35 provided in the reflection plate 34 through which the ultrasonic waves pass may be arbitrary, and by making them larger or smaller than the holes provided in the flow path 11, desired correct reflection can be achieved. Only waves can be brought in.

When such a reflecting plate 34 is provided, the ultrasonic pulses that reach the reflecting plate 34 are scattered by the reflecting plate 34 and return to the liquid level 17 side through an unnecessary path, and then to the ultrasonic level meter transmitter 19 side. The level of the ultrasonic waves that reach this point is significantly lower, and there is no possibility of it being detected as a false signal pulse.

Further, the reflecting plate 34 of the present invention is provided near the mounting portion 18 and is relatively far from the liquid level 17, so there is little possibility that the reflecting plate 34 will come into contact with the fluid. Even if foreign matter adheres to the reflector 34,
Only the reflectance of the reflector 34 decreases, and there is no effect thereof.

Although the reflector 34 of the present invention is provided with holes 35,
This hole may be of any shape, such as circular or square.
It is also possible to change the size of this hole for installation. Since the hole size can be changed, the mounting part 18
The diameter of the hole can be made smaller than the diameter of the hole, and unnecessary reflections can be completely eliminated, allowing accurate measurements.

As described above, the present invention is applied to the Palmer bolus frium type flowmeter, and is particularly effective when the surface facing the liquid level to be measured is a concave curved surface.

<Effects of the Invention> As described above, according to the mounting structure of the ultrasonic level meter of the present invention, it is possible to eliminate the influence of unnecessary reflected waves from the liquid surface to be measured, and to obtain correct liquid level values.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a Furium type flowmeter, Fig. 2 is a sectional view taken along the line A-A, Figs. 3 and 4 are sectional views corresponding to Fig. 2 showing the path of reflected waves, respectively. Fig. 5 is a sectional view corresponding to Fig. 1 showing an example of a conventional mounting structure of an ultrasonic level meter applied to a fluum type flowmeter, and Fig. 6 is a sectional view corresponding to Fig. 2. FIG. 7 is a cross-sectional view corresponding to FIG. 6 showing another example in which the conventional mounting structure of an ultrasonic level meter is applied to a frium type flow meter, and FIG. 8 is a cross-sectional view showing yet another conventional example. FIG. 9 is a diagram showing an example of a mounting structure for an ultrasonic level meter according to this invention. 11... Channel, 11a, 11b... Side wall, 12
...Furium, 17...Liquid level, 18...Mounting section, 19...Ultrasonic level meter transmitter, 20...Concave curved surface, 34...Reflector, 35...Hole.

Claims (1)

[Scope of utility model registration request] In the mounting structure of an ultrasonic level meter installed in a flow path in which a Palmer bolus frium is installed and the inner surfaces of at least both side walls of the ultrasonic transducer mounting part are concave curved surfaces with respect to the measured liquid level. ,
Correct ultrasonic waves from the liquid surface to be measured are passed through opposite to the mounting part of the transducer so as to prevent reflected ultrasonic waves from the liquid surface to be measured from being re-reflected to the transducer. A reflecting plate is provided with a hole formed therein, bent from approximately the center so that the ridge line faces the liquid surface, and fixed on both sides to the concave curved surface of the inner surface of the side wall of the flow channel. Mounting structure for ultrasonic level meter.