JP2000266583A - Portable liquid level judging apparatus, standard member for calibration and liquid level judging method within internal space of object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the judgment from the outside of whether a liquid such as water is inside a pipe or the like or not. SOLUTION: In this portable liquid level judging apparatus, a probe 4 is applied on the external surface of an object to transmit an ultrasonic signal inside it. The ultrasonic signal propagating through the liquid inside to be reflected and received is displayed on a CRT7 with a delay in time from the transmitted signal. If no liquid exists, the ultrasonic signal propagating through the liquid is not received thereby enabling the judging of the liquid level depending on whether the liquid exists or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable liquid level for externally determining the level of a liquid surface when a liquid exists inside an object such as a container for storing a fluid or a pipe for transporting the fluid. The present invention relates to a determination device, a calibration standard member, and a liquid level determination method in an internal space of an object.

[0002]

2. Description of the Related Art Generally, the presence or absence of liquid in a container or a transportation route is determined by
The determination can be made only in a portion that has been prepared for confirmation or detection in advance. For example, the presence / absence of a liquid is determined from the outside unless there is a structure in which it is possible to directly visually check whether or not a liquid is present inside, or if some kind of detection means is provided. It is very difficult to do.

The necessity of judging the presence or absence of a liquid is, for example, when water is mixed in a supply pipe for city gas and a supply failure occurs, the existence of a liquid is not expected. This is particularly necessary when no is provided. If a gas supply failure occurs, even if it is presumed to be due to water leakage, appropriate measures cannot be taken unless the leakage is directly confirmed.

[0004]

For example, as a method of detecting water leakage in a supply pipe for city gas, a radiation transmission test, an ultrasonic flaw detection test, and the like can be considered. Since the radiation transmission test requires a large-scale inspection device and requires several hours until an inspection result is obtained, it is difficult to apply the radiation transmission test as a method that can easily determine the presence or absence of water leakage. In order to apply an ultrasonic wave such as an ultrasonic flaw detection test to the determination of the presence or absence of water leakage, it is necessary to develop a device and a method that can easily and effectively determine the liquid level in a pipe.

SUMMARY OF THE INVENTION An object of the present invention is to provide a portable liquid level determining apparatus and a calibration standard member capable of determining the liquid level inside an object using ultrasonic waves, and a liquid level judging method in the internal space of the object. It is to be.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a device which is housed in a portable housing and is capable of judging the liquid level in an internal space of an object to be judged from the outside. A probe that transmits ultrasonic waves to the inside of the object to be determined and receives a reflected wave, a drive circuit that electrically drives the probe to generate ultrasonic waves for transmission, and a probe. The ultrasonic signal received by the stylus is compared with the timing of the electric drive of the drive circuit, and it is determined whether or not the received signal includes a component that has propagated in the liquid inside the determination target object. A judgment circuit for judging that the contact position of the probe is below the liquid level when the medium propagation component is included, a display for displaying the judgment result of the judgment circuit outside the housing, and a calibration standard member prepared in advance Based on the received signal obtained by bringing the probe into contact with And a positive calibration circuit, housing is
A portable liquid level determination device comprising a holding unit capable of holding the calibration standard member.

According to the present invention, when the probe is brought into contact with the outer surface of the object to be determined and the ultrasonic wave is transmitted inside the object to be determined, the liquid exists inside the object to be determined, and the ultrasonic wave is contained in the liquid. If the signal is propagated, the ultrasonic signal propagated through the liquid and reflected can be received by the probe. The determination circuit compares the ultrasonic signal received by the probe with the electrical drive timing of a drive circuit that causes the probe to generate ultrasonic waves for transmission. Whether or not the received signal has propagated in the liquid can be determined based on a time delay from the transmission time of the ultrasonic signal. When the determination circuit determines that the component propagated in the liquid is included, the determination circuit determines that the contact position of the probe is below the liquid level, and the display unit displays the determination result outside the housing. When the probe is brought into contact with the liquid above the liquid level, the ultrasonic signal propagating through the liquid is not generated. Therefore, referring to the display, the contact position of the probe is below or above the liquid level. Can be easily determined, and the liquid level inside the object can be easily determined from the outside. The housing is provided with a holding portion capable of holding a calibration standard member, and a calibration circuit for calibrating a criterion of a determination circuit based on a received signal obtained by bringing a probe into contact with a calibration standard member prepared in advance. Is included, the criterion of the determination circuit can be calibrated at any time so that the determination of the liquid level can be performed with high accuracy.

Further, the present invention relates to a calibration standard member used in a portable liquid level judging device, comprising a cylinder having a bottom and a predetermined shape, a liquid filled in the cylinder, and a liquid filled in the cylinder. And a lid that seals the cylindrical body, transmits an ultrasonic signal from the outer surface of the lid, reflects off the inner surface of the lid and returns to the outer surface, and propagates from the inner surface of the lid into the liquid Then, a calibration standard member capable of receiving the ultrasonic signal reflected by passing through the liquid, the reflected signal passing back through the lid, and returning to the outer surface by the probe of the portable liquid level determination device. .

According to the present invention, the inside of the bottomed cylinder is filled with a liquid and sealed with a lid. When an ultrasonic signal is transmitted from the outer surface of the lid, it is reflected on the inner surface and returns to the outer surface of the lid. And the reflected signal that passes through the lid and returns to the outer surface can be received by the probe of the portable liquid level determination device. Since the cylindrical body has a predetermined shape, the reflected signal reflected back inside the lid and the reflected signal returned through the liquid can be easily identified as a time difference from the ultrasonic transmission time. Can be. Therefore, the criterion of the determination circuit of the portable liquid level determination device can be easily calibrated.

Further, the present invention is a method for judging a liquid level in a space from the outside of an object having a space therein, wherein a signal is transmitted by ultrasonic waves from the outer surface of the object, The liquid is stored in the object according to whether or not a signal that passes through the outer wall, is transmitted into the liquid from the inner surface of the outer wall, propagates through the liquid, is reflected, and returns to the outer wall is received, and the ultrasonic wave is applied. A liquid level determination method in an object internal space, which determines whether a signal transmission position is below a liquid level.

According to the present invention, it is possible to easily know from outside using ultrasonic waves whether or not there is a liquid inside the object and whether the ultrasonic wave transmission position is above or below the liquid level. it can. Further, it is also possible to easily know whether or not the container or the transport pipe is filled with the liquid.

[0012]

FIG. 1 shows an external configuration of a portable liquid level judging device according to an embodiment of the present invention. In the portable liquid level determination device, an electric circuit portion is housed in a housing 1.
A display 2 and an operation switch 3 are arranged on the surface of the housing 1. A probe 4 that transmits an ultrasonic wave to a determination target and receives a reflected wave is connected to the housing 1 via a connection cord 5. The housing 1 is also provided with a test piece holder 6 for holding a test piece for performing calibration for liquid level determination by bringing the probe 4 into contact therewith.

The display 2 has a CRT (cathode ray tube) 7 for displaying the waveform of the reflected wave received after transmitting the ultrasonic wave,
There are provided a numerical display 8 for displaying a numerical value with a segment type light emitting diode, a lamp 9 using a light bulb or a light emitting diode, and the like. CRT 7 and numerical display 8 for waveform display
Can be replaced by a liquid crystal display (LDC) or the like. The operation switch 3 includes a power switch, a switch for adjusting the reception sensitivity of the probe 4, a switch for adjusting display on the CRT 7, and the like.

FIG. 2 shows an outline of an electric configuration of the portable liquid level judging device shown in FIG. The processing circuit 10 including the microcomputer determines the presence or absence of a signal component that has passed through the liquid surface based on the received signal of the ultrasonic wave, and functions as a determination circuit that determines whether the liquid surface exists. It also functions as a calibration circuit for calibrating the criterion of the determination circuit. The memory 11 includes a ROM and a RAM. In the ROM, a program for causing a microcomputer in the processing circuit 10 to function as a determination circuit or a calibration circuit is stored in advance. The drive circuit 12 performs electrical drive for transmitting ultrasonic waves by the ultrasonic transmission element in the probe 4.
The transmission of the ultrasonic wave is performed on the pulse, and the transmission is stopped when the reflected wave is received. That is, the transmission of the ultrasonic wave is performed in a fixed short period, the reception of the ultrasonic signal is performed in the reception period longer than the transmission period, and the transmission of the ultrasonic wave is periodically repeated. The ultrasonic signal received by the receiving element in the probe 4 is electrically converted and amplified by the receiving circuit 13. The timing of transmission by the drive circuit 12 and the reception signal received by the reception circuit 13 are provided to the processing circuit 10. Operation power for the processing circuit 10, the memory 11, the driving circuit 12, and the receiving circuit 13 is supplied from a battery 14.

FIG. 3A shows a cross-sectional shape of a test piece 15 used as a calibration standard member in the portable liquid level determination device of FIG. The test piece 15 is a cylindrical cylinder 1
6, a disk-shaped bottom 17 and a lid 18 are inserted from both sides in the axial direction to form an airtight space inside, and the space is filled with water 19. The cylindrical body 16 is made of steel, has an outer diameter of about 6 mm, and has an axial length of 10 m.
m. The thickness of the cylindrical body 16 is about 1.5 mm, and the thickness of the bottom 17 and the lid 18 is about 2 mm. The test piece holding portion 6 of FIG. 1 that holds such a test piece 15 can be formed on the surface of the housing 1 as a round hole whose inside diameter is slightly larger than the outside diameter of the cylindrical body 16.

A portable liquid level determination device as shown in FIG.
It has basically the same configuration as a portable ultrasonic flaw detector used conventionally. FIG. 3B shows a cross-sectional shape of the test piece 20 for an ultrasonic flaw detector. The test piece 20 has a steel column shape as a whole, and has no space inside.

FIG. 4 shows the principle of detecting the liquid level in the present invention. When the ultrasonic wave is perpendicularly incident on the boundary surface 23 between the two substances, the steel 21 and the water 22, the sound pressure reflectance r that determines the ratio of the reflected wave and the transmitted wave is given by the following equation 1. .

[0018]

(Equation 1)

Here, Z ₁ and Z ₂ are steel 21 and water 2
2 shows the acoustic impedance. Acoustic impedance is the product of the density and speed of sound, the sound velocity and density in the steel 21 and C ₁ and [rho _1, when the acoustic velocity and density in the water 22 and C ₂ and [rho _2, the acoustic impedance Z _1, Z ₂ is expressed by the following equations 2 and 3.

Z ₁ = ρ ₁ × C ₁ (2) Z ₂ = ρ ₂ × C ₂ (3) When the boundary surface 23 is a combination of the steel 21 and the water 22, the sound pressure reflectance r is 0. 0.9, the reflected wave is about 90% of the incident wave, and the passing wave is about 10%. Water 2
2 is reflected from the opposite boundary surface or the surface of the water 22 and reenters the boundary surface 23,
The rate of returning to 1 is called the sound pressure reciprocating passage rate T and is expressed by the following equation 4.

T = 1−r ² (4) When a gas such as air or city gas is present in place of the water 22, the acoustic impedance of the gas is extremely small as compared with the steel 21, so that the ultrasonic wave Total reflection at 23,
Some features do not propagate in the end. That is, if the water 22 exists, not only the reflected wave at the boundary surface 23 but also the water 2
2 can be received again as a reflected wave, whereas when only water and no gas are present, only the reflected wave from the boundary surface 23 can be received. Is the basic principle of the present invention.

FIG. 5 shows a state in which a leak check test is performed by applying the basic principle shown in FIG. When the probe 4 is brought into contact with the outer peripheral surface of the polyethylene tube 24 in a state in which water 25 is filled in the polyethylene tube 24 which is a polyethylene tube, and the contact position is changed in the axial direction, reflection occurs. The presence of the water 25 and its liquid level can be determined from the wave reception state. The polyethylene tube 24 has an outer diameter of 32 mm and is manufactured according to a standard called 32A, for example.

FIGS. 6A and 6B show reception waveforms of ultrasonic signals at the positions 4a and 4b of the probe 4 shown in FIG. 5, respectively. The transmission of the ultrasonic signal starts from time t0, and the polyethylene pipe 2
The reflected wave from the inner peripheral surface of No. 4 is observed. After time t2, the ultrasonic wave propagates from the inner peripheral surface of the polyethylene tube 24 into the water 25, and a received waveform that is reflected by the inner peripheral surface of the opposite polyethylene tube 24 and returns is observed. At the contact position 4a in FIG. 5 shown in FIG. 6A, since no water 25 exists inside, the reflected wave after time t2 is not received. FIG. 6 (b)
As shown in (2), if water 25 is present, a reflected wave can be received after time t2. If a reception waveform as shown in FIG. 6B is obtained, it can be determined that liquid such as water 25 is present, and generally it is determined that water 25 is present due to water leakage. it can.

FIG. 7 shows the detection result of water 25 in the zinc pipe 26. "No water" shown in FIG.
The result of “with water” shown in (b) is the contact position 4a of the probe 4 with the outer surface of the zinc pipe 26 shown in FIG.
And 4b respectively. Also in the zinc pipe 26, when the water 25 is present, a received wave that passes through the water 25 and is reflected is observed, and the observation point is:
It can be seen that it corresponds to the shape of the zinc pipe 26.

The probe position 4b of the probe 4 shown in FIG.
The position of the reflected wave after time t2 in (b) also corresponds to the shape of the polyethylene tube 24. Generally, if the shape of the container storing the liquid such as water 25 is known, the time until the reflected wave returns can be easily calculated. The test piece 15 as shown in FIG.
If the shapes of the cylindrical body 16, the bottom 17 and the lid 18 are known,
The time required until the reflected wave is received can be easily narrowed down. Therefore, as shown in FIGS. 6 and 7,
By receiving or neglecting the reflected waves inside the tube walls of the polyethylene pipe 24 and the zinc pipe 26, the reflected waves that have passed through the liquid such as the water 25 can be easily identified.

FIG. 8 shows a water pipe 31 adjacent to a low-pressure main pipe 30 for supplying city gas buried underground.
1 shows a state in which it is determined whether or not water has leaked from the inside of the low-pressure main pipe 30 due to water leakage. It is assumed that city gas is supplied from the low-pressure main pipe 30 to a customer gas meter 33 via a supply pipe 32. If the present invention is applied, the supply pipe 32
If the water level has risen to the exposed part of the
The presence of moisture can be easily determined by contacting the probe 4 to the outer peripheral surface of the device, and the presence or absence of water leakage can be easily determined.

FIG. 9 shows a state in which it is determined whether or not the pipe 35 is filled with the liquid 36. When the tube 35 is filled with the liquid 36, the same result can be obtained by applying the probe 4 from any direction on the outer peripheral surface of the tube 35. However, it is generally easier to bring the probe 4 into contact with the upper part of the tube 35 as shown in FIG.

FIG. 11 shows a case where the fluid 35 is not completely filled in the pipe 35, that is, a case where a space exists and a liquid level of the fluid 36 also exists. In such a case, the tube 3
5 needs to be brought into contact with the probe 4. When the pipe 35 is buried underground, it is necessary to excavate below the pipe 35 to expose the lower part of the pipe 35.

FIG. 12 shows the waveform of the reflected wave when the liquid surface of the liquid 36 exists inside the tube 35. FIGS. 12A and 12B correspond to the contact positions 4a and 4b of the probe 4 shown in FIG. 12C, respectively. Upper contact position 4
In the received waveform shown in (a) with respect to a, it is understood that the reflected wave that has passed through the liquid 36 is not received. In the received waveform of FIG. 12B corresponding to the contact position 4b of the probe 4 below the tube 35, it can be seen that the received waveform reflected on the liquid surface of the liquid 36 is detected.

In the present invention, the principle of determining the liquid level is based on the difference between the acoustic impedance of a solid such as a tube, the acoustic impedance of a liquid, and the acoustic impedance of a gas. Almost no liquid can be detected, and the liquid level can be determined. Therefore, liquids of highly corrosive chemicals such as hydrochloric acid and sulfuric acid can be detected. Also, for example, it can be easily determined from the outside whether or not a deodorant to be added to add a smell to the city gas is present in the pipe for addition. As the material of the tube, any material capable of transmitting ultrasonic waves can be applied, and any material such as a steel tube, a vinyl chloride tube, a polyethylene tube, a copper tube, a metal tube, or a synthetic resin tube can be used. However, since the probe 4 needs to be brought into contact with the surface to transmit ultrasonic waves and receive ultrasonic signals, the present invention cannot be applied to a tube having a complicated outer shape.

Further, according to the present invention, not only the presence of the liquid inside the pipe but also the presence of the liquid inside the container or the like is determined in the same manner, and the liquid level can be easily determined.

[0032]

As described above, according to the present invention, the probe is brought into contact with the outer surface of the object, the ultrasonic wave is transmitted, and the liquid inside the object is determined based on the received ultrasonic signal. Can be easily determined, and the position of the liquid level can be easily determined based on whether or not the liquid is detected due to the change in the contact position of the probe.

Further, according to the present invention, it is possible to easily perform calibration so that the portable liquid level determination device can reliably perform the liquid level determination based on the presence or absence of the ultrasonic signal transmitted through the liquid.

Further, according to the present invention, the liquid level in the object can be easily determined using an ultrasonic signal.
Therefore, it is possible to easily determine the presence or absence of water leakage in the gas supply pipe where there is normally no liquid.

[Brief description of the drawings]

FIG. 1 is a simplified front view showing a schematic configuration of a portable liquid level determination device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an electrical configuration of the portable liquid level determination device of FIG.

3 is a cross-sectional view showing a test piece used for the portable liquid level determination device of FIG. 1 and a test piece used for a conventional ultrasonic flaw detector.

FIG. 4 is a diagram showing a principle by which the present invention can determine that a liquid exists.

FIG. 5 is a simplified cross-sectional view showing a state in which it is determined whether or not water 25 is present in a polyethylene pipe 24 assuming water leakage using the principle of FIG.

FIG. 6 is a graph showing waveforms of ultrasonic signals received at the probe positions 4a and 4b of the probe 4 in FIG. 5, respectively.

FIG. 7 is a graph showing a reception waveform for determining the presence or absence of water 25 on the zinc pipe 26, and a simplified cross-sectional view showing a determination state.

FIG. 8 is a simplified cross-sectional view showing a configuration capable of confirming the presence or absence of water leakage in a city gas supply pipe 32 by applying the present invention.

FIG. 9 is a simplified cross-sectional view showing a state in which a liquid filled in a pipe is detected.

FIG. 10 is a perspective view showing a state in which a liquid filled in a tube 35 is determined by applying a probe 4 thereto.

FIG. 11 is a simplified cross-sectional view showing a contact position of the probe 4 when a space exists due to the partial presence of the fluid 36 in the pipe 35.

FIG. 12 is a graph showing a reception waveform corresponding to whether the contact position of the probe 4 is above or below the tube 35 when the liquid 36 partially exists in the tube 35, and It is sectional drawing which shows a position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Display 4 Probe 6 Test piece holding part 7 CRT 8 Numerical display part 9 Lamp 10 Processing circuit 11 Memory 12 Drive circuit 13 Receiving circuit 15 Test piece 16 Cylindrical body 17 Bottom 18 Lid 19,22 Water 21 Steel 23 Boundary surface 24 Polyethylene pipe 26 Zinc pipe 30 Low-pressure main pipe 31 Water pipe 32 Supply pipe 33 Gas meter 35 Pipe 36 Fluid

Claims (3)

[Claims] 1. A device which is housed in a portable housing and is capable of judging a liquid level in an internal space of an object to be judged from the outside. A probe that transmits ultrasonic waves to the probe and receives reflected waves, a drive circuit that electrically drives the probe to generate ultrasonic waves for transmission, and an ultrasonic wave that is received by the probe The signal and the timing of the electric drive of the drive circuit are compared, and it is determined whether or not the received signal includes a component that has propagated in the liquid inside the determination target object. A determination circuit that determines that the contact position of the probe is below the liquid level, a display that displays the determination result of the determination circuit outside the housing, and a probe that is brought into contact with a calibration standard member that is prepared in advance. A calibration circuit for calibrating the criterion of the determination circuit based on the obtained reception signal. , Housing the portable liquid level determining apparatus comprising: a holding unit capable of holding the 該較 Tadashiyo standard member. 2. A standard member for calibration used in the portable liquid level determination device according to claim 1, wherein: a cylinder having a bottom and a predetermined shape; a liquid to be filled in the cylinder; A lid for sealing the filled cylinder, transmitting an ultrasonic signal from the outer surface of the lid, reflecting a signal from the inner surface of the lid and returning to the outer surface, A calibration standard member capable of receiving, by the probe of the portable liquid level determination device, an ultrasonic signal transmitted through the liquid and reflected by the liquid and returned to the outer surface through the lid. 3. An object having a space inside from outside.
A method for determining a liquid level in the space, wherein a signal is transmitted by ultrasonic waves from the outer surface of the object, passes through the outer wall of the object, is transmitted into the liquid from the inner surface of the outer wall, and passes through the liquid. The liquid is stored in the object and whether the transmission position of the ultrasonic signal is below the liquid level is determined in accordance with whether or not a signal which is propagated and reflected and returns again through the outer wall is received. A method for determining a liquid level in an internal space of an object, characterized by determining.