JP2000009519A - Ultrasonic level gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an ultrasonic level gauge, which measures the liquid level in a liquid storage part such as a tank and a pit, to securely measure the liquid level, even when the area of the liquid surface of the liquid storage part is small or when there is an obstacle in the liquid storage part, and to securely measure the liquid level without any mutual interference between >=2 ultrasonic level gauges even when they are arranged closely to each other. SOLUTION: An ultrasonic-wave transmitter/receiver 3 which is so arranged to sent an ultrasonic wave 14 at right angles to the liquid surface 16 of the liquid 2 put in the liquid storage part 1, and a signal processing part 6 which finds the distance from the ultrasonic-wave transmitter/receiver 3 to the liquid surface 16 according to transmit and receive wave signals from the ultrasonic- wave transmitter/receiver 3, are provided above the liquid surface 16 of the liquid 2 and to the ultrasonic-wave transmitter/receiver 3. A diffusion preventive structure 21 is added which prevent the transmitted ultrasonic wave 14 from being diffused.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic level gauge suitable for measuring the level of liquid in a liquid container such as a tank or a pit.

[0002]

2. Description of the Related Art An ultrasonic level gauge is used to measure the level of a liquid contained in a liquid container such as a tank or a pit. 2. Description of the Related Art As a conventional ultrasonic liquid level meter, there is one shown in the configuration diagram (partly in cross-sectional view) of FIG. The ultrasonic transceiver 3 is installed on the support 16 while being supported by the support 4, and the ultrasonic transceiver 3 is connected to the signal processing unit 6 by the cable 5. The signal processing unit 6 includes:
The temperature sensor 17 is connected by the cable 18, and the display unit 8 is connected by the cable 7.

[0003] Ultrasonic waves 14 are transmitted from the ultrasonic transceiver 3 toward the liquid surface 16, and the ultrasonic echo waves 15 reflected on the liquid surface 16 are received by the ultrasonic transceiver 3. In the signal processing unit 6, the transmission / reception wave is input from the ultrasonic transmitter / receiver 3, and the ambient temperature of the gas in the liquid storage unit 1 measured by the temperature sensor 17 is input. The distance between the ultrasonic transmitting / receiving surface of the ultrasonic transmitting / receiving device 3 and the liquid surface 16, that is, the liquid level, is determined from the propagation speed of the sound in the gas in the liquid container 1 corrected by the measured ambient temperature. calculate. The calculated liquid level information is
The liquid is sent to the display unit 8 and the liquid level is displayed on the display unit 8.

[0004]

However, the conventional ultrasonic liquid level meter as described above may not be able to accurately measure the liquid level due to the characteristics of the ultrasonic waves. That is, since the ultrasonic wave has a weak directivity and has a characteristic of spreading toward the liquid surface 16 as shown by a hatched region (ultrasonic propagation range) 20 in FIG. If there is an object that reflects a sound wave, an echo wave of an ultrasonic wave will be reflected from the object.

In addition, there is no problem if this object is sufficiently farther than the distance between the ultrasonic transmitter / receiver of the ultrasonic transmitter / receiver 3 and the liquid surface 16, but from the ultrasonic transmitter / receiver of the ultrasonic transmitter / receiver 3 to the object. When the distance is short, the echo wave from the object interferes with the echo wave from the liquid surface 16 and the liquid level cannot be measured accurately. For example, when the area of the liquid level 16 of the liquid storage unit is small due to a small pit or the bottom area of the tank is small, or when there is an obstacle on the liquid level 16 in the liquid storage unit such as a pit or a tank. Since the echo wave reflected by the wall surface or obstacle around the liquid surface 16 interferes with the echo wave from the liquid surface 16, the liquid level cannot be measured accurately.

[0006] Even if the liquid container such as a pit or a tank is sufficiently wide and the echo wave from the wall surrounding the liquid surface 16 does not hinder the measurement of the liquid level, the liquid level is not reduced.
When installing more than one ultrasonic level gauge, the ultrasonic waves of each ultrasonic level gauge will interfere if the ultrasonic level gauges adjacent to each other are installed close to each other. There is also a problem that the ultrasonic level gauges cannot be used unless they are separated from each other by a distance that does not interfere with each other so that the ultrasonic waves do not interfere.

The present invention has been made in view of the above-described problems, and can reliably measure the liquid level even when the liquid surface area of the liquid container is small or when there is an obstacle in the liquid container. It is an object of the present invention to provide an ultrasonic level gauge capable of reliably measuring a liquid level without interfering with each other even when two or more ultrasonic level gauges are arranged close to each other.

[0008]

According to the present invention, there is provided an ultrasonic liquid level gauge according to the present invention, wherein the liquid level of the liquid stored in the liquid storing portion is perpendicular to the liquid level. An ultrasonic transmitter / receiver arranged to transmit ultrasonic waves in a direction, and a signal processing for obtaining a distance from the ultrasonic transmitter / receiver to the liquid surface based on a transmission / reception wave signal from the ultrasonic transmitter / receiver The ultrasonic transceiver is provided with a diffusion preventing structure for preventing the transmitted ultrasonic waves from diffusing.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram (partly a cross-sectional view) showing an ultrasonic level gauge as one embodiment of the present invention. is there. As shown in FIG. 1, a liquid 2 is stored in a concrete pit 1 as a liquid storage unit. The present ultrasonic level gauge includes an ultrasonic transceiver 3 disposed above the pit 1 so as to transmit ultrasonic waves in a direction perpendicular to the liquid surface 16, A signal processing unit 6 is connected to the device 3 via a cable 5 and processes a transmission / reception signal from the ultrasonic transceiver 3 to calculate a liquid level.

The signal processing section 6 has a temperature sensor 17 for detecting the ambient temperature of the gas in the pit 1.
And a display section 8 for displaying the liquid level calculated by the signal processing section 6 via the cable 7. As a result, in the signal processing unit 6, the ultrasonic transceiver 3
When the transmission / reception wave is input from the controller and the ambient temperature of the gas in the liquid storage unit 1 measured by the temperature sensor 17 is input, the liquid storage corrected by the time difference between the transmission and reception and the ambient temperature measured by the temperature sensor 17. The ultrasonic transmission / reception surface of the ultrasonic transmission / reception device 3 and the liquid level 16
, That is, the liquid level is calculated, and the calculated liquid level information is sent to the display unit 8.

If the ambient temperature is constant, the temperature sensor 17 and the cable 18 can be omitted. In this ultrasonic level meter, the ultrasonic transmitter / receiver 3 transmits ultrasonic waves (hereinafter referred to as “ultrasonic transmission waves”) 14 transmitted from the ultrasonic transmitter / receiver 3 as an ultrasonic conduction as a diffusion preventing structure. A tube 21 is provided.

That is, below the ultrasonic transmitter / receiver 3 (in the ultrasonic transmission direction), the cylindrical pipe 9 is disposed in a direction perpendicular to the liquid surface 16, the intermediate part is fixed to the support 4, and the lower end is fixed to the support 4. An opening is provided near the bottom surface for facilitating infiltration of the liquid, and is submerged in the liquid surface 16. Above the cylindrical pipe 9, a cylindrical pipe 11 is installed via an intermediate table 10, and above the cylindrical pipe 11, an ultrasonic transceiver mounting portion 12 is fixed.

Ultrasonic conduction tube 21 as diffusion preventing structure
Is composed of the cylindrical pipe 9 and the intermediate table 10, the cylindrical pipe 11, the ultrasonic transmitter / receiver mounting part 12, and the sound absorbing material (rubber, cork, etc.) 13 installed inside the cylindrical pipe 11. . That is, the ultrasonic transmitter / receiver 3 is attached to the ultrasonic transmission tube 21 below the ultrasonic transmitter / receiver mounting portion 12, and the ultrasonic transmitter / receiver mounting portion 1 is provided.
2. It is arranged in a space defined by a cylindrical pipe 11 and an intermediate base 10. In addition, a hole 10A is formed in the center of the intermediate table 10, and among the ultrasonic waves 14 transmitted from the ultrasonic transmitting / receiving section 3A of the ultrasonic transmitting / receiving
Only components directed in a direction substantially perpendicular to the direction are sent to the liquid surface side. In addition, the sound absorbing material 13 has the hole 1
The inner surface (upper surface) of the intermediate table 10 is covered so as not to block 0A.

Therefore, the ultrasonic transmitter / receiver 3 is surrounded by the ultrasonic transmitter / receiver mounting portion 12 on the upper side (rear side), by the cylindrical pipe 11 on the side, and by the intermediate table 10 on the lower side (ultrasonic transmission / reception direction). Further, the lower part in the cylindrical pipe 11, that is, a region (ultrasonic propagation range) 20 where the ultrasonic transmission wave 14 from the ultrasonic transceiver 3 is diffused.
A sound absorbing material 13 is provided in the inside (see FIG. 2).

As a result, the diffused component of the ultrasonic transmission wave 14 from the ultrasonic transmitter / receiver 3 collides mainly with the cylindrical pipe 11 and the sound absorbing material 13 inside the cylindrical pipe 11 and is reflected or absorbed. It does not spread below the intermediate table 10. Here, since the cylindrical pipe 11 itself does not absorb sound, the transmission wave 14 hitting the cylindrical pipe 11 is reflected, but the liquid surface 16 side below the exposed portion of the cylindrical pipe 11 is not reflected. Since the transmission wave 14 reflected by the cylindrical pipe 11 is covered with the sound absorbing material 13, the transmission wave 14 is not absorbed by the sound absorbing material 13 and diffused below the intermediate base 10 to travel.

The cylindrical pipe 9 below the intermediate table 10
This also assists in preventing diffusion of the ultrasonic transmission wave 14 transmitted below the intermediate table 10. In other words, even if the ultrasonic transmission wave 14 is prevented from being diffused by the cylindrical pipe 11 and the sound absorbing material 13, the ultrasonic transmission wave 14 does not propagate without spreading below the intermediate table 10. Although it is very slight, it spreads below the intermediate table 10.

The sound pressure of the ultrasonic transmission wave 14 thus diffused is very small, and there is not much problem in detecting the echo wave of the ultrasonic transmitter / receiver 3 itself which has transmitted the ultrasonic transmission wave 14, but the ultrasonic wave 14 has no problem. When the ultrasonic transceiver 3 is installed,
Even if the sound pressure of the transmitted ultrasonic transmission wave 14 is slight, it may interfere with each other and affect the detection of the echo wave.
The cylindrical pipe 9 is provided to avoid such a fear.

Since the ultrasonic level gauge as one embodiment of the present invention is configured as described above, the ultrasonic transceiver 3
Transmits the ultrasonic transmission wave 14 and receives the ultrasonic echo wave 15 reflected by the liquid surface 16 of the liquid 2. Then, the transmission / reception wave signal at this time is transmitted to the signal processing unit 6 via the cable 5. At the same time, the atmospheric temperature of the gas in the liquid container 1 measured by the temperature sensor 17 is
8 to the signal processing unit 6.

The detection signal processor 6 determines the ultrasonic transmission / reception time of the ultrasonic transmitter / receiver 3 based on the transmitted / received time difference and the propagation speed of the sound in the gas in the liquid container 1 corrected by the transmitted ambient temperature. The distance between the sound wave transmitting / receiving surface and the liquid surface 16, that is, the liquid level is calculated, and the calculated liquid level information is sent to the display unit 8. Then, the liquid level information is displayed on the display unit 8. By the way, the ultrasonic transmission wave 14 transmitted from the ultrasonic transmitter / receiver 3 toward the liquid surface 16 of the liquid 2 normally spreads toward the liquid surface 2 as in an ultrasonic propagation range 20 shown in FIG. In the ultrasonic level gauge of the present invention, the ultrasonic transmission tube 21 is provided as a diffusion preventing structure for preventing the ultrasonic transmission wave 14 from diffusing.
Proceed toward the liquid surface 2 without diffusion.

That is, the diffuse component of the ultrasonic transmission wave 14 transmitted from the ultrasonic transmission / reception unit 3A of the ultrasonic transmission / reception unit 3 is the cylindrical pipe 11 or the sound absorbing material 1 in the diffusion region.
3, the ultrasonic transmitter / receiver mounting part 12, the cylindrical pipe 1
1, only the component of the ultrasonic transmission wave 14 that is directed in a direction substantially orthogonal to the liquid surface 16 is transmitted below the intermediate table 10 because it is confined in the space defined by the intermediate table 10. .

As described above, the ultrasonic transmission wave 14 is provided with directivity and is transmitted below the intermediate table 10. Even below the intermediate table 10, a part of the ultrasonic transmission wave 14 is extremely small. But it spreads. Although the sound pressure of the ultrasonic transmission wave 14 thus diffused is small, in the present ultrasonic level gauge, since the cylindrical pipe 9 is disposed below the intermediate base 10, the ultrasonic transmission wave 14 Progresses in the cylindrical pipe 9.

The ultrasonic transmission wave 14 is reflected on the liquid surface 16 to become an echo wave 15 and travels toward the ultrasonic transmission / reception section 3A of the ultrasonic transmission / reception device 3. The ultrasonic transmission wave 14 component spread below the intermediate stage 10 travels while being reflected on the inner surface of the ultrasonic cylindrical pipe 9, and similarly, a part of the echo wave 15 is also transmitted to the ultrasonic cylindrical pipe 9. 9 While proceeding while reflecting on the inner surface, such an ultrasonic component
Since the sound pressure level is extremely low as compared with an ultrasonic component which is given directivity and travels in a direction perpendicular to the liquid surface 16, it does not hinder liquid level measurement.

As described above, in the present ultrasonic liquid level meter, since the ultrasonic waves used for liquid level measurement travel only in the ultrasonic transmission tube 21, the ultrasonic waves are located on the side walls of the liquid storage section such as a pit or a tank or in the liquid storage section. The liquid level can be accurately measured without being affected by existing obstacles, and when the surface area of the liquid surface 16 of the liquid storage unit is small, such as a narrow pit or a tank with a small bottom area, or when the liquid in the liquid storage unit is small. Even when there is an obstacle on the surface 16, the liquid level can be accurately measured.

Further, since the ultrasonic wave travels only in the ultrasonic conduction tube 21, even when the ultrasonic transceivers 3 are installed close to each other, they interfere with each other and affect the liquid level detection. Therefore, the liquid level can be accurately measured by the respective ultrasonic transceivers 3. Therefore, even when a plurality of ultrasonic transceivers 3 are installed, they can be freely arranged such that they are arranged close to each other.

The ultrasonic level gauge of the present invention is not limited to the above-described embodiment, but can be implemented in various modifications without departing from the spirit of the present invention. In particular, the diffusion prevention structure only needs to be able to prevent diffusion of the ultrasonic transmission wave, and the configuration and shape of the diffusion prevention structure are not limited to the above-described embodiment. For example, in the above-described embodiment, the ultrasonic transmission tube 21 is connected to the cylindrical pipe 9 and the intermediate table 10, the cylindrical pipe 11, the ultrasonic transceiver attaching section 1
2 and the sound absorbing material 13 provided inside the cylindrical pipe 11, but the sound absorbing material 13 can be omitted if the intermediate table 10 and the inner surface of the cylindrical pipe 11 have sound absorbing properties.
In this case, the diffused component of the ultrasonic transmission wave 14 is absorbed by the intermediate table 10 and the inner surface of the cylindrical pipe 11 having a sound absorbing property, thereby preventing the ultrasonic transmission wave 14 from diffusing.

Further, by reducing the inner diameter of the cylindrical pipe 11 or forming the cylindrical pipe 11 into a funnel shape in which the diameter of the cylindrical pipe 11 is reduced downward, the cylindrical pipe 11 also serves as the intermediate base 10 and Omission of the intermediate stage 10 and the cylindrical piping 11
It is also conceivable to integrate In addition, cylindrical piping 1
The ultrasonic transmitter / receiver mounting portion 12 may also be used as 1.

Further, in the ultrasonic transmission tube 21, the diffusion of the ultrasonic transmission wave 14 below the intermediate table 10 is prevented by the cylindrical pipe 9, but the ultrasonic transmission wave below the intermediate table 10 is prevented. If the diffusion of 14 is not a problem, the cylindrical pipe 9
May be omitted. Furthermore, when a plurality of ultrasonic transmitters / receivers 3 are installed, the cylindrical pipe 9 can be omitted even if the intervals can be made so as not to interfere with each other.

When the cylindrical pipe 9 is omitted, some member is connected to the support 4 to support the ultrasonic transceiver 3, the cylindrical pipe 11, and the like. Even when the cylindrical pipe 9 is omitted in this manner, the ultrasonic transceivers 3 are installed close to each other and are not easily affected by obstacles existing in the side wall of the liquid container and the liquid container. In this case as well, it is difficult to interfere with each other, so that an effect similar to that of the above embodiment can be obtained.

[0029]

As described in detail above, according to the ultrasonic level gauge of the present invention, the diffusion preventing structure prevents the ultrasonic wave transmitted from the ultrasonic transceiver from diffusing. It is less susceptible to the obstacles existing in the side wall of the liquid storage unit and the liquid storage unit, and when the surface area of the liquid surface of the liquid storage unit is small, such as a narrow pit or a tank with a small bottom area, Even when there is an obstacle, there is an advantage that the liquid level can be accurately measured.

Further, even when the ultrasonic transceivers are installed close to each other, it is difficult for the ultrasonic waves to interfere with each other. Therefore, even if two or more ultrasonic water level gauges are arranged close to each other, The liquid level can be reliably measured without interference.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an ultrasonic level gauge as one embodiment of the present invention, and a part thereof is shown in cross section.

FIG. 2 is a configuration diagram showing a conventional ultrasonic level gauge, and a part thereof is shown in cross section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Concrete pit as liquid storage part 2 Liquid 3 Ultrasonic transceiver 3A Ultrasonic transceiver 4 Support 5 Cable 6 Signal processing part 7 Cable 8 Display part 9 Cylindrical piping 10 Intermediate stand 10A hole 11 Cylindrical piping 12 Ultrasonic Transceiver mounting part 13 Sound absorbing material 14 Ultrasonic wave (ultrasonic transmission wave) 15 Ultrasonic wave (echo wave) 16 Liquid surface 17 Temperature sensor 18 Cable 20 Ultrasonic propagation range 21 Ultrasonic conduction tube as diffusion prevention structure

Claims (1)

[Claims] An ultrasonic transmitter / receiver disposed above a liquid surface of a liquid stored in a liquid storage portion so as to transmit ultrasonic waves in a direction orthogonal to the liquid surface; A signal processing unit for calculating a distance from the ultrasonic transceiver to the liquid level based on a transmission / reception wave signal from the ultrasonic transceiver, and preventing the transmitted / received ultrasonic wave from being diffused to the ultrasonic transceiver. An ultrasonic level gauge, further comprising a diffusion preventing structure.