JPS604101Y2 - Wavebreak tube for ultrasonic level meter - Google Patents

Description

[Detailed description of the invention] This invention mainly relates to a wavebreak tube for an ultrasonic level meter that measures the liquid level, and in particular eliminates the inconvenience that occurs when the liquid level to be measured falls below the lower end of the wavebreak tube. The purpose of this project is to provide a structure for a breakwater pipe that is possible.

Generally, an ultrasonic level meter emits ultrasonic waves 3 from an ultrasonic receiver 1 toward a surface to be measured 2, as shown in Fig. 1, receives the reflected waves, and calculates the return and return time of the surface to be measured 2. It measures the level.

When the object to be measured is a liquid, if the surface of the liquid is rippled, the reflected waves cannot be received accurately, so a wave break tube 4 is used as shown in FIG. 2.

When liquid is stored in a tank or the like, when the liquid level is close to the top of the tank, the liquid level will ripple due to the influence of wind and other factors.

As another example, in a tank or the like, the closer the liquid level is to the top of the tank, the greater the amount of liquid stored, so in such cases, a dumping machine is often operated to dump the liquid.

Therefore, in consideration of such a case, a wave break tube 4 is provided to surround the reflecting surface 2 of the ultrasonic wave 3 with the wave break tube 4 to prevent the waves from being applied to the reflecting surface.

However, when the liquid level to be measured decreases, the liquid level moves away from the lower end of the breakwater pipe 4, as shown in FIG.

If the opening surface at the lower end of the wavebreak tube 4 is cut so as to be perpendicular to its axis, the acoustic impedance changes sharply at this opening end surface, so the ultrasonic waves 3 are reflected at this portion. This method has the disadvantage that erroneous measurements are performed based on the assumption that a liquid level exists.

For this reason, it is conceivable to extend the breakwater pipe 4 to near the bottom of a tank or the like, but since containers such as tanks are generally deep in many cases, there is a drawback that the breakwater pipe 4 becomes long and the cost increases.

Further, as the liquid level approaches the bottom, the ripples decrease, so there is little need for the breakwater tube 4 near the bottom.

This idea proposes a structure in which the wavebreak tube is only as long as necessary, and ultrasonic waves will not be reflected at the lower end surface even if the liquid level drops below the bottom end of the wavebreak tube. be.

In this invention, there are sections with different distances between the lower edge of the wavebreak tube and the ultrasonic transducer, so that the change in acoustic impedance in these sections is made to gradually change.

FIG. 4 shows an embodiment of this invention.

4 in the figure indicates a breakwater pipe.

This example shows a case where the lower end edge 5 of the breakwater pipe 4 is cut at an angle of θ with respect to the axis of the pipe 4.

By inclining the lower end edge of the wavebreak tube 4 at an angle other than perpendicular to the axis, the acoustic impedance at the lower end of the wavebreak tube 4 can be gradually changed between the inside and outside of the wavebreak tube 4. can.

Therefore, ultrasonic waves are not reflected at this portion, and even if the liquid level falls below the lower end of the wave break tube 4, it is possible to avoid performing erroneous measurements.

5 to 8 show other embodiments of this invention.

In the example shown in FIG. 5, unevenness 6 is formed on the lower edge 5 of the breakwater pipe 4,
A case is shown in which a portion having a different distance from the ultrasonic transducer 1 to the lower end edge 5 of the wave break tube 4 is formed by the unevenness 6.

The example shown in FIG. 6 shows a case where the lower end edge 5 of the breakwater tube 4 is formed in a corrugated shape.

Further, as shown in FIG. 7, the lower end edge 5 of the wavebreak pipe 4 is cut diagonally as in the embodiment shown in FIG. 4, and unevenness 6 is formed on the cut edge.

Further, the example shown in FIG. 8 shows a case where the lower end edge 5 of the breakwater tube 4 is formed in a stepped shape.

Even when formed in this way, the change in acoustic impedance at the boundary between the lower end of the breakwater tube 4 and the outside of the tube 4 gradually changes, making it possible to achieve a non-reflection end.

Therefore, according to this invention, reflection at the lower end of the wave break tube 4 can be avoided without making the wave break tube 4 long, and an inexpensive ultrasonic level meter that does not generate false signals can be provided.

[Brief explanation of the drawing]

Figure 1 is a side view explaining an ultrasonic level meter, Figure 2 is a cross-sectional view explaining a wavebreak tube used in an ultrasonic level meter, and Figure 3 is an explanation of the drawbacks of conventional wavebreak tubes. Fig. 4 is a sectional view showing an embodiment of this invention;
Figures 8 through 8 are sectional views showing other embodiments of this invention. 1: Ultrasonic transducer, 2: Measured liquid level, 4: Wavebreak pipe, 5
: Lower edge.

Claims (1)

[Scope of utility model registration request] An ultrasonic transducer is attached to the upper end, and the lower end is extended toward the liquid surface to be level measured, and surrounds the reflecting surface of the ultrasonic wave on the liquid surface to be measured to prevent ripples on the reflecting surface. A wavebreak tube for an ultrasonic level meter, which is provided with a portion having a different distance between the opening edge at the lower end of the wavebreak tube and the ultrasonic transducer.