A kind of spherical container liquid level detection system and detection method based on piezoelectric micro-mechanical ultrasonic transducer and ultrasonic guided wave

Abstract

This invention discloses a liquid level detection system and method for a spherical container based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided wave. The system includes a spherical container with a transmitting end and a receiving end piezoelectric micromechanical ultrasonic probe. The vertical height of the transmitting end piezoelectric micromechanical ultrasonic probe is no higher than a specified minimum liquid level in the spherical container. The receiving end piezoelectric micromechanical ultrasonic probe is located above the transmitting end piezoelectric micromechanical ultrasonic probe. The center of the transmitting signal of the transmitting end piezoelectric micromechanical ultrasonic probe and the center of the receiving signal of the receiving end piezoelectric micromechanical ultrasonic probe pass through the center of the spherical container. The transmitting end piezoelectric micromechanical ultrasonic probe is connected to an ultrasonic signal excitation module, and the receiving end piezoelectric micromechanical ultrasonic probe is connected to a signal processing module. The signal processing module is connected to a host computer, which uses the ultrasonic signal processed by the signal processing module to calculate the liquid level in the spherical container.

Description

Technical Field

[0001] This invention belongs to the field of liquid level detection technology for spherical containers, specifically relating to a liquid level detection system and method for spherical containers based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided waves. Background Technology

[0002] Liquid level detection technology is widely used in aerospace, petrochemical, and biopharmaceutical industries. It is commonly used to detect changes in the liquid level within containers to achieve purposes such as automated control, monitoring of abnormal liquid level changes, and flow statistics. Common liquid level detection technologies include reed float detection, capacitance detection, X-ray detection, and ultrasonic detection methods.

[0003] The reed float method has advantages such as simple structure, low cost, and strong anti-interference, but it is a contact measurement with a small measurement range and cannot measure inclined or dynamic liquid surfaces. The capacitance detection method is easily affected by the dielectric constant of the liquid and foam impurities, and cannot measure corrosive liquids or dynamic liquid surfaces. X-ray detection has advantages such as high accuracy, fast response speed, and a wide range of detectable media, but it is costly, requires numerous and bulky auxiliary equipment, and carries radiation risks. The ultrasonic detection method utilizes the waveform changes caused by the difference in acoustic impedance of the medium along the ultrasonic propagation path. By analyzing the echo signal of the ultrasonic wave, relevant information about the liquid level in the container can be obtained. It has advantages such as high accuracy, real-time monitoring capability, non-contact measurement, and strong robustness, and has broad development prospects in the field of liquid level detection.

[0004] Currently, research on the application of ultrasound in liquid level detection has made some progress. Researchers have proposed a detection method based on ultrasonic time-of-flight for liquid level detection, verifying its feasibility through finite element simulation analysis. Liquid level detection in vertical pipes has been conducted in a laboratory environment. However, this method is limited to vertical pipes, restricting its application and resulting in low accuracy. To meet the needs of non-invasive liquid level detection in high-temperature environments in nuclear power plants, researchers have designed a laser-generated ultrasonic method for liquid level detection. This method has been successfully implemented in a 200°C laboratory environment for measuring liquid levels in vertical pipes. However, this method is also designed for pipes with vertical walls, and while suitable for nuclear power plants, it cannot detect spherical or other complex structures. Other researchers have designed an ultrasonic liquid level detection scheme based on ultrasonic impedance and time-of-flight methods, applicable to vertical sidewall tanks. This scheme improves accuracy by compensating for the differences between the two methods. However, this method requires a large number of ultrasonic probes, and its experimental verification was conducted on cubic tanks, similarly limiting its application to spherical or other shaped containers.

[0005] Furthermore, the current sensing units used in ultrasonic liquid level detection are mainly traditional block-shaped ultrasonic probes. These ultrasonic probes have drawbacks such as large size, high power consumption, and acoustic impedance mismatch. With the continuous advancement of microelectromechanical systems technology in recent years, the advantages of micromechanical ultrasonic transducers, such as miniaturization, low power consumption, good acoustic impedance matching characteristics, easy integration with ICs, and mass production, have gradually attracted the attention of the industry and have begun to be applied in various ultrasonic testing fields. In the field of ultrasonic liquid level detection, micromechanical ultrasonic transducers also have broad application prospects.

[0006] In summary, existing ultrasonic level detection methods can directly or indirectly detect the liquid level in straight-walled containers, exhibiting good accuracy and stability in the non-invasive detection field. However, current applications of ultrasonic detection are mainly concentrated on vertically walled containers. Research on level detection in slightly more complex containers, such as spherical containers or horizontally placed cylindrical pipes, is still lacking, and few related detection schemes and system designs have been proposed. Regarding ultrasonic probes, micromechanical ultrasonic transducers, as emerging sensing elements, have untapped potential in the field of ultrasonic level detection. Summary of the Invention

[0007] To address the problem of liquid level detection in spherical cross-section containers, the present invention aims to provide a liquid level detection system and method for spherical containers based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided waves. This invention utilizes ultrasonic guided wave signal analysis to achieve liquid level detection for containers with complex structures, particularly spherical containers and horizontally placed cylindrical pipes, obtaining highly accurate liquid level detection results.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A liquid level detection system for a spherical container based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic waveguide includes a spherical container. A transmitting piezoelectric micromechanical ultrasonic probe and a receiving piezoelectric micromechanical ultrasonic probe are mounted on the spherical container. The vertical height of the transmitting piezoelectric micromechanical ultrasonic probe is no higher than a specified minimum liquid level in the spherical container. The receiving piezoelectric micromechanical ultrasonic probe is located above the transmitting piezoelectric micromechanical ultrasonic probe. The center of the transmitting signal of the transmitting piezoelectric micromechanical ultrasonic probe and the center of the receiving signal of the receiving piezoelectric micromechanical ultrasonic probe pass through the center of the spherical container.

[0010] The transmitting end piezoelectric micromechanical ultrasonic probe is connected to an ultrasonic signal excitation module, and the receiving end piezoelectric micromechanical ultrasonic probe is connected to a signal processing module. The signal processing module is connected to a host computer, which is used to calculate the liquid level in the spherical container using the ultrasonic signal processed by the signal processing module.

[0011] Preferably, the receiving piezoelectric micromechanical ultrasonic probe includes an upper receiving piezoelectric micromechanical ultrasonic probe, the vertical height of which is not lower than the highest liquid level specified in the spherical container (1), and the host computer calculates the liquid level in the spherical container according to the following formula. H :

[0012]

[0013]

[0014]

[0015] In the formula, V k 、V m These figures represent the peak-to-peak value of the ultrasonic guided wave received signal by the piezoelectric micromechanical ultrasonic probe at the receiving end when the spherical container is empty, and the peak-to-peak value of the ultrasonic guided wave received signal by the piezoelectric micromechanical ultrasonic probe at the receiving end when the spherical container is full, respectively. V d This represents the peak-to-peak value of the ultrasonic guided wave received signal received by the piezoelectric micromechanical ultrasonic probe at the upper receiving end during the measurement of the liquid level in the spherical container, under the condition of the liquid level to be measured inside the spherical container. α The angle between the line connecting the signal transmission center of the piezoelectric micromechanical ultrasonic probe at the transmitting end and the center of the spherical container, and the vertical axis of the spherical container. β The angle between the line connecting the upper receiving end piezoelectric micromechanical ultrasonic probe to the center of the spherical container and the line connecting the signal transmission center of the transmitting end piezoelectric micromechanical ultrasonic probe to the center of the spherical container on the vertical plane. R Let the radius of the spherical descriptor be . θ The angle between the line connecting the edge of the liquid level to be measured inside the spherical container and the center of the circle, and the vertical axis of the spherical container.

[0016] Preferably, both the transmitting piezoelectric micromechanical ultrasonic probe and the receiving piezoelectric micromechanical ultrasonic probe are located on the circumference of the cross section passing through the center of the spherical container in the vertical direction, and both are located on the same side of the vertical axis of the spherical container.

[0017] Preferably, the receiving piezoelectric micromechanical ultrasonic probe includes an upper receiving piezoelectric micromechanical ultrasonic probe and a lower receiving piezoelectric micromechanical ultrasonic probe. The vertical height of the upper receiving piezoelectric micromechanical ultrasonic probe is not lower than the specified highest liquid level in the spherical container, and the vertical height of the lower receiving piezoelectric micromechanical ultrasonic probe is located at the midpoint between the upper receiving piezoelectric micromechanical ultrasonic probe and the transmitting piezoelectric micromechanical ultrasonic probe. The host computer calculates the liquid level in the spherical container according to the following formula.H :

[0018]

[0019]

[0020]

[0021] In the formula, V k 、V m These figures represent the peak-to-peak values ​​of the ultrasonic guided wave received signals received by the piezoelectric micromechanical ultrasonic probe at the receiving end and the lower receiving end when the spherical container is empty, and the peak-to-peak values ​​of the ultrasonic guided wave received signals received by the piezoelectric micromechanical ultrasonic probe at the receiving end and the lower receiving end when the spherical container is full. V 1d , V 2d These represent the peak-to-peak value of the ultrasonic guided wave received signal received by the piezoelectric micromechanical ultrasonic probe at the receiving end and the peak-to-peak value of the ultrasonic guided wave received signal received by the piezoelectric micromechanical ultrasonic probe at the lower receiving end, respectively, during the measurement of the liquid level in the spherical container under the condition of the liquid level to be measured inside the spherical container. α The angle between the line connecting the signal transmission center of the piezoelectric micromechanical ultrasonic probe at the transmitting end and the center of the spherical container, and the vertical axis of the spherical container. β The angle between the line connecting the upper receiving end piezoelectric micromechanical ultrasonic probe to the center of the spherical container and the line connecting the signal transmission center of the transmitting end piezoelectric micromechanical ultrasonic probe to the center of the spherical container on the vertical plane. R Let the radius of the spherical descriptor be . θ The angle between the line connecting the edge of the liquid level to be measured inside the spherical container and the center of the circle, and the vertical axis of the spherical container.

[0022] Preferably, the transmitting piezoelectric micromechanical ultrasonic probe, the upper receiving piezoelectric micromechanical ultrasonic probe, and the lower receiving piezoelectric micromechanical ultrasonic probe are all located on the circumference of the cross section passing through the center of the spherical container in the vertical direction, and are all located on the same side of the vertical axis of the spherical container.

[0023] Preferably, the spherical container is provided with a piezoelectric micromechanical ultrasonic probe fixing device on its exterior, and both the transmitting end piezoelectric micromechanical ultrasonic probe and the receiving end piezoelectric micromechanical ultrasonic probe are mounted on the piezoelectric micromechanical ultrasonic probe fixing device.

[0024] Preferably, a coupling layer is provided between the spherical container and the transmitting piezoelectric micromechanical ultrasonic probe, as well as between the spherical container and the receiving piezoelectric micromechanical ultrasonic probe.

[0025] Preferably, both the ultrasonic signal excitation module and the signal processing module are connected to the host computer. The host computer is used to control the ultrasonic signal excitation module to generate ultrasonic signals from the piezoelectric micromechanical ultrasonic probe at the transmitting end. The host computer is also used to receive the ultrasonic signals processed by the signal processing module, as well as to collect and record signals, and to calculate the liquid level in the spherical container using the collected signals.

[0026] This invention also provides a method for detecting the liquid level in a spherical container based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided waves. This method utilizes the spherical container liquid level detection system based on the piezoelectric micromechanical ultrasonic transducer and ultrasonic guided waves described in this invention. The method includes the following steps:

[0027] The ultrasonic signal excitation module controls the piezoelectric micromechanical ultrasonic probe at the transmitting end to generate ultrasonic signals; the piezoelectric micromechanical ultrasonic probe at the receiving end receives ultrasonic guided wave signals; the signal processing module processes the ultrasonic guided wave signals received by the piezoelectric micromechanical ultrasonic probe at the receiving end, and the host computer uses the ultrasonic signals processed by the signal processing module to calculate the liquid level in the spherical container.

[0028] Preferably, the signal processing module performs signal processing on the ultrasonic guided wave signal received by the piezoelectric micromechanical ultrasonic probe at the receiving end, including signal noise reduction, signal filtering, and signal amplification.

[0029] The present invention has the following beneficial effects:

[0030] This invention presents a spherical container liquid level detection system based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided waves. This system boasts advantages such as simple structure and flexible installation. Both the transmitting and receiving piezoelectric micromechanical ultrasonic probes are mounted on the spherical container and do not contact the liquid inside. It does not require embedding within the container, thus employing non-contact, non-destructive testing to meet higher measurement requirements. Operation and maintenance costs are low, eliminating the need for periodic consumable replacements. It also offers good scalability, allowing for the replacement of different types of ultrasonic probes. The spherical container liquid level detection system based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided waves requires only contact between the liquid inside the spherical container and its wall. It has low requirements for the internal structure and shape of the spherical container, making it applicable to various types of containers and exhibiting strong versatility and universality. This invention uses a piezoelectric micromechanical ultrasonic transducer as an ultrasonic probe (i.e., a piezoelectric micromechanical ultrasonic probe at the transmitting end and a piezoelectric micromechanical ultrasonic probe at the receiving end). Because this type of ultrasonic probe has advantages such as miniaturization, flexible design, and easy integration, it can be installed in a small space.

[0031] Furthermore, the spherical container is equipped with a piezoelectric micromechanical ultrasonic probe fixing device. Both the transmitting and receiving piezoelectric micromechanical ultrasonic probes are mounted on the fixing device, thus fixing the positions of the transmitting and receiving ultrasonic probes. When the liquid level is between the transmitting and receiving ends, the liquid level can be measured based on the change in the ultrasonic guided wave received signal. Because the detection system is stably installed and less affected by human factors and environmental interference, the ultrasonic liquid level detection system has good stability and high detection accuracy. Attached Figure Description

[0032] Figure 1 A schematic diagram of the structure of a spherical container liquid level detection system based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guide wave, provided in an embodiment of the present invention;

[0033] Figure 2 A diagram showing the positional relationship between a spherical container, a piezoelectric micromechanical ultrasonic probe at the transmitting end, a piezoelectric micromechanical ultrasonic probe at the receiving end, and the liquid level to be measured, provided in an embodiment of the present invention.

[0034] Figure 3 This is a flowchart of the ultrasonic guided wave liquid level detection method provided in an embodiment of the present invention;

[0035] Figure 4 This is a flowchart of the ultrasonic guided wave signal acquisition process provided in an embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the liquid level detection calculation results provided in an embodiment of the present invention;

[0037] Figure 6 This is a schematic diagram of the micromechanical ultrasonic transducer array structure provided in an embodiment of the present invention;

[0038] Reference numerals: 1-Spherical container, 2-Piezoelectric micromechanical ultrasonic probe at the transmitting end, 3-Piezoelectric micromechanical ultrasonic probe at the upper receiving end, 4-Piezoelectric micromechanical ultrasonic probe at the lower receiving end, 5-Piezoelectric micromechanical ultrasonic probe fixing device, 6-Ultrasonic signal excitation module, 7-Signal processing module, 8-Host computer. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this technical solution clearer, the following detailed description, in conjunction with specific embodiments, further illustrates this technical solution. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this technical solution.

[0040] To address the problem of liquid level detection in complex spherical containers, this invention proposes a liquid level detection system and method for spherical containers based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided waves. By analyzing the changes in the ultrasonic guided waves after propagation within the container wall, the specific liquid level inside the container is calculated. This method employs a fixed ultrasonic probe for detection, typically using a piezoelectric micromechanical ultrasonic transducer as the detection unit. This allows for installation of the detection equipment in confined spaces and offers advantages such as high accuracy, good stability, and strong environmental adaptability in liquid level detection.

[0041] This embodiment is based on a spherical container liquid level detection system using a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided waves. It includes a spherical container 1, on which a transmitting piezoelectric micromechanical ultrasonic probe 2 and a receiving piezoelectric micromechanical ultrasonic probe are mounted. The vertical height of the transmitting piezoelectric micromechanical ultrasonic probe 2 is no higher than the minimum liquid level specified in the spherical container 1. The receiving piezoelectric micromechanical ultrasonic probe is located above the transmitting piezoelectric micromechanical ultrasonic probe 2. The transmission signal center of the transmitting piezoelectric micromechanical ultrasonic probe 2 and the reception signal center of the receiving piezoelectric micromechanical ultrasonic probe both pass through the center of the spherical container 1. The transmitting piezoelectric micromechanical ultrasonic probe 2 is connected to an ultrasonic signal excitation module 6, which excites the transmitting piezoelectric micromechanical ultrasonic probe 2 to generate ultrasonic signals. The ultrasonic waves generated by the transmitting piezoelectric micromechanical ultrasonic probe 2 are reflected multiple times on the inner wall of the spherical container 1 to form ultrasonic guided waves, which propagate along the inner wall of the spherical container 1 and are received by the receiving piezoelectric micromechanical ultrasonic probe. The receiving piezoelectric micromechanical ultrasonic probe is connected to a signal processing module 7. The signal processing module 7 performs preliminary processing of the ultrasonic guided wave signal received by the receiving piezoelectric micromechanical ultrasonic probe. Specific processing includes signal noise reduction, signal filtering, and signal amplification to improve the signal-to-noise ratio and intensity. The processed ultrasonic guided wave signal is then transmitted to a host computer 8. The signal processing module 7 is connected to the host computer 8, which uses the processed ultrasonic signal to calculate the liquid level in the spherical container 1. In this embodiment, both the transmitting and receiving piezoelectric micromechanical ultrasonic probes use piezoelectric micromechanical ultrasonic transducers as sensing units, which are miniaturized and adaptable to confined installation spaces.

[0042] The liquid level detection system for a spherical container based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided waves provided in the above embodiments includes the following steps for detecting the liquid level inside the spherical container:

[0043] The ultrasonic signal excitation module 6 controls the piezoelectric micromechanical ultrasonic probe 2 at the transmitting end to generate ultrasonic signals; the piezoelectric micromechanical ultrasonic probe at the receiving end receives the ultrasonic guided wave signals; the signal processing module processes the ultrasonic guided wave signals received by the piezoelectric micromechanical ultrasonic probe at the receiving end, and the host computer 8 uses the ultrasonic signals processed by the signal processing module 7 to calculate the liquid level in the spherical container 1. The signal processing module 7 is mainly used to preprocess the ultrasonic guided wave signals received by the piezoelectric micromechanical ultrasonic probe at the receiving end to improve the signal-to-noise ratio and amplify the signal. The signal processing module's signal processing of the ultrasonic guided wave signals received by the piezoelectric micromechanical ultrasonic probe at the receiving end includes signal noise reduction, signal filtering, and signal amplification.

[0044] As an optional embodiment of the present invention, in this embodiment, when one piezoelectric micromechanical ultrasonic probe is provided (i.e., using the upper receiving piezoelectric micromechanical ultrasonic probe 3), reference is made. Figure 2 The vertical height of the upper receiving end piezoelectric micromechanical ultrasonic probe 3 is not lower than the specified highest liquid level in the spherical container 1. The host computer 8 calculates the liquid level in the spherical container 1 according to the following formula. H :

[0045]

[0046]

[0047]

[0048] In the formula, V k 、V m These figures represent the peak-to-peak values ​​of the ultrasonic guided wave received signal received by the piezoelectric micromechanical ultrasonic probe at the receiving end of the spherical container 1 when it is empty, and the peak-to-peak values ​​of the ultrasonic guided wave received signal received by the piezoelectric micromechanical ultrasonic probe at the receiving end of the spherical container 1 when it is full, respectively. V d This represents the peak-to-peak value of the ultrasonic guided wave received signal received by the piezoelectric micromechanical ultrasonic probe 3 at the upper receiving end during the measurement of the liquid level in the spherical container 1, under the condition of the liquid level to be measured in the spherical container 1. α Let be the angle between the line connecting the signal transmission center of the piezoelectric micromechanical ultrasonic probe 2 at the transmitting end and the center of the spherical container 1, and the vertical axis of the spherical container 1. β The angle between the line connecting the upper receiving end piezoelectric micromechanical ultrasonic probe 3 to the center of the spherical container 1 and the line connecting the signal transmission center of the transmitting end piezoelectric micromechanical ultrasonic probe 2 to the center of the spherical container 1 on the vertical plane. R Let be the radius of spherical container 1. θThe angle between the line connecting the edge of the liquid level to be measured inside the spherical container 1 and the center of the circle and the vertical axis of the spherical container 1.

[0049] As a preferred embodiment of the present invention, for ease of calculation, based on the above embodiments, in this embodiment, the transmitting end piezoelectric micromechanical ultrasonic probe 2 and the upper receiving end piezoelectric micromechanical ultrasonic probe 3 are both located on the circumference of the cross section passing through the center of the spherical container 1 in the vertical direction, and the transmitting end piezoelectric micromechanical ultrasonic probe 2 and the upper receiving end piezoelectric micromechanical ultrasonic probe 3 are both located on the same side of the vertical axis of the spherical container 1.

[0050] As another optional embodiment of the present invention, in this embodiment, two piezoelectric micromechanical ultrasonic probes can be provided (i.e., an upper piezoelectric micromechanical ultrasonic probe 3 and a lower piezoelectric micromechanical ultrasonic probe 4 are used), see reference. Figure 2 The vertical height of the upper receiving piezoelectric micromechanical ultrasonic probe 3 is not lower than the specified highest liquid level in the spherical container 1. The vertical height of the receiving piezoelectric micromechanical ultrasonic probe 4 is located at the midpoint between the upper receiving piezoelectric micromechanical ultrasonic probe 3 and the transmitting piezoelectric micromechanical ultrasonic probe 2. The host computer 8 calculates the liquid level in the spherical container 1 according to the following formula. H :

[0051]

[0052]

[0053]

[0054] In the formula, V k 、V m These figures represent the peak-to-peak values ​​of the ultrasonic guided wave received signals received by the piezoelectric micromechanical ultrasonic probe 3 and the lower piezoelectric micromechanical ultrasonic probe 4 when the spherical container 1 is empty, and the peak-to-peak values ​​of the ultrasonic guided wave received signals received by the piezoelectric micromechanical ultrasonic probe 3 and the lower piezoelectric micromechanical ultrasonic probe 4 when the spherical container 1 is full. V 1d , V 2d These represent the peak-to-peak value of the ultrasonic guided wave received signal received by the piezoelectric micromechanical ultrasonic probe 3 at the receiving end and the peak-to-peak value of the ultrasonic guided wave received signal received by the piezoelectric micromechanical ultrasonic probe 4 at the lower receiving end, respectively, during the measurement of the liquid level in the spherical container 1. α Let be the angle between the line connecting the signal transmission center of the piezoelectric micromechanical ultrasonic probe 2 at the transmitting end and the center of the spherical container 1, and the vertical axis of the spherical container 1. βThe angle between the line connecting the upper receiving end piezoelectric micromechanical ultrasonic probe 3 to the center of the spherical container 1 and the line connecting the signal transmission center of the transmitting end piezoelectric micromechanical ultrasonic probe 2 to the center of the spherical container 1 on the vertical plane. R Let be the radius of spherical container 1. θ The angle between the line connecting the edge of the liquid level to be measured inside the spherical container 1 and the center of the circle and the vertical axis of the spherical container 1.

[0055] As a preferred embodiment of the present invention, for ease of calculation, based on the above embodiments, in this embodiment, the transmitting end piezoelectric micromechanical ultrasonic probe 2, the upper receiving end piezoelectric micromechanical ultrasonic probe 3, and the lower receiving end piezoelectric micromechanical ultrasonic probe 4 are all located on the circumference of the cross section passing through the center of the spherical container 1 in the vertical direction, and the transmitting end piezoelectric micromechanical ultrasonic probe 2, the upper receiving end piezoelectric micromechanical ultrasonic probe 3, and the lower receiving end piezoelectric micromechanical ultrasonic probe 4 are all located on the same side of the vertical axis of the spherical container 1.

[0056] In the above-mentioned solution of the present invention, the specific liquid level calculation procedure needs to be adjusted according to the changes in the actual detection conditions such as the size of the container to be tested, the thickness of the container wall, and the material of the container wall. This calculation method is mainly designed for spherical containers and can be adapted to containers of various shapes and sizes, including spherical storage tanks, horizontally placed cylindrical pipes, etc.

[0057] In a preferred embodiment of the present invention, a piezoelectric micromechanical ultrasonic probe fixing device 5 is provided on the outside of the spherical container 1. Both the transmitting piezoelectric micromechanical ultrasonic probe 2 and the receiving piezoelectric micromechanical ultrasonic probe are mounted on the fixing device 5. In this embodiment, since both the transmitting and receiving piezoelectric micromechanical ultrasonic probes are mounted on the fixing device, the positions of the transmitting and receiving ultrasonic probes are fixed. When the liquid level is between the transmitting and receiving ends, the liquid level can be measured based on the change in the ultrasonic guided wave received signal. Because the detection system is stably installed and less affected by human factors and environmental interference, the ultrasonic liquid level detection system has good stability and high detection accuracy.

[0058] In a preferred embodiment of the present invention, the ultrasonic probe fixing device tightly fixes the transmitting ultrasonic probe and the receiving ultrasonic probe to the outer side of the container wall of the spherical cross-section container. A suitable coupling layer needs to be provided between the ultrasonic probe and the container wall. Therefore, in this embodiment, coupling layers are provided between the spherical container 1 and the transmitting piezoelectric micromechanical ultrasonic probe 2, as well as between the spherical container 1 and the receiving piezoelectric micromechanical ultrasonic probe. The use of coupling layers ensures good quality of the generated and received ultrasonic guided wave signals, which is beneficial to improving the accuracy of the detection results.

[0059] In a preferred embodiment of the present invention, both the ultrasonic signal excitation module 6 and the signal processing module 7 are connected to the host computer 8. The host computer 8 can be an industrial computer, a regular PC, an embedded host computer, or other types. Utilizing its storage and computing functions, the host computer 8 can control the operation of the ultrasonic signal excitation module 6, causing the piezoelectric micromechanical ultrasonic probe 2 at the transmitting end to generate ultrasonic signals, thus controlling the generation of ultrasonic signals. Simultaneously, the host computer 8 can also receive the ultrasonic signals processed by the signal processing module 7, perform signal acquisition and recording, and calculate the liquid level in the spherical container 1 using the acquired signals and a pre-set ultrasonic liquid level calculation algorithm. See also... Figure 4 In this embodiment, the host computer activates the ultrasonic signal excitation module 6 to control the piezoelectric micromechanical ultrasonic probe 2 at the transmitting end to generate ultrasonic signals; the receiving end piezoelectric micromechanical ultrasonic probe receives the ultrasonic guided wave signals; the received ultrasonic guided wave signals are transferred to the signal processing module 7, which amplifies, filters, and reduces noise before transmitting them to the host computer, which then collects and records the signals for subsequent signal processing and calculation.

[0060] See Figure 3 In the above embodiments of the present invention, when the spherical container 1 is empty, a first ultrasonic guided wave signal acquisition is performed, and the peak-to-peak value of the ultrasonic guided wave signal is extracted by the host computer and recorded as the peak-to-peak value in the empty container state. When the spherical container 1 is filled with the liquid to be tested, a second ultrasonic guided wave signal acquisition is performed, and the peak-to-peak value of the ultrasonic guided wave signal is extracted by the host computer and recorded as the peak-to-peak value in the full container state. The liquid level in the spherical container 1 to be tested is detected, and the specific operation method is as follows: When the liquid level in the pipe is unknown, the host computer controls the piezoelectric micromechanical ultrasonic probe at the transmitting end to generate ultrasonic guided waves, which are received by the piezoelectric micromechanical ultrasonic probe at the receiving end and transmitted back to the host computer, completing one ultrasonic guided wave signal acquisition. The peak-to-peak value of the ultrasonic guided wave signal at this time is recorded as the peak-to-peak value in the test state. The host computer can calculate the liquid level in the pipe to be tested based on the functional relationship between the peak-to-peak value in the test state, the peak-to-peak value in the empty container state, and the peak-to-peak value in the full container state, as well as the fixed positions of the transmitting and receiving ultrasonic probes.

[0061] Furthermore, the solution of the above embodiments of the present invention can also be applied to the measurement of liquid level in a horizontally arranged cylindrical pipe. The liquid level calculation process therein is similar to the liquid level calculation process in the spherical container of the present invention. The geometric relationships in the liquid level calculation process in the spherical container of the present invention (such as...) Figure 2 (As shown) is the geometric relationship of a cross section of a cylindrical horizontal pipe that is perpendicular to its axis.

[0062] The above-mentioned solution of the present invention is based on the principle of ultrasonic guided wave attenuation, that is, when ultrasonic guided waves propagate in a thin plate, the degree of energy attenuation of ultrasonic guided waves will change when the media on both sides of the thin plate are different; therefore, when the liquid level in a container (such as a spherical container or a cylindrical horizontal pipe) changes, the liquid level in the container can be calculated based on the degree of attenuation of the ultrasonic guided wave signal in the container wall.

[0063] In the above-described embodiment of the present invention, the ultrasonic probe is a piezoelectric micromechanical transducer, which can be used in confined ultrasonic probe installation environments to adapt to more complex and challenging conditions. If necessary, a conventional ultrasonic transducer can be used to replace the piezoelectric micromechanical transducer.

[0064] In the above-described scheme of the present invention, the detection range and detection accuracy are based on the coverage of the ultrasonic probe. If necessary, the detection range and detection accuracy can be increased by increasing the number of ultrasonic probes.

[0065] Example 1

[0066] like Figure 1 As shown, this embodiment of the spherical container liquid level detection system based on piezoelectric micromechanical ultrasonic transducers and ultrasonic guided waves includes a spherical container 1, a transmitting piezoelectric micromechanical ultrasonic probe 2, an upper receiving piezoelectric micromechanical ultrasonic probe 3, a lower receiving piezoelectric micromechanical ultrasonic probe 4, a piezoelectric micromechanical ultrasonic probe fixing device 5, an ultrasonic signal excitation module 6, a signal processing module 7, and a host computer 8. The piezoelectric micromechanical ultrasonic probe fixing device 5 fixes the transmitting piezoelectric micromechanical ultrasonic probe 2, the upper receiving piezoelectric micromechanical ultrasonic probe 3, and the lower receiving piezoelectric micromechanical ultrasonic probe 4 to the outer wall of the spherical container 1. The ultrasonic signal excitation module 6 connects the transmitting piezoelectric micromechanical ultrasonic probe 2 and the host computer 8 via a data transmission line. The signal processing module 7 connects the upper receiving piezoelectric micromechanical ultrasonic probe 3, the lower receiving piezoelectric micromechanical ultrasonic probe 4, and the host computer 8 via a data transmission line.

[0067] This embodiment describes a method for detecting liquid level in a spherical container based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided waves, including the following steps (see...). Figure 3 ):

[0068] Step (1), according to Figure 1 The diagram shows the ultrasonic guided wave liquid level detection system. The various parts of the ultrasonic guided wave liquid level detection system are installed.

[0069] Step (2), the process of acquiring an ultrasonic guided wave signal ( Figure 4The system is controlled by a host computer, which activates the ultrasonic signal excitation module to control the ultrasonic probe at the transmitting end to generate ultrasonic signals. After the ultrasonic signals are transmitted into the container wall, some of the ultrasonic waves are dispersed and propagated along the container wall to form ultrasonic guided waves, which are then transmitted to the ultrasonic probes at the upper and lower receiving ends for reception. The received ultrasonic guided wave signals are then transferred to the signal processing module, where they are amplified, filtered, and noise-reduced before being transmitted to the host computer for signal acquisition and recording for subsequent signal processing and calculation.

[0070] Step (3): Before detecting the liquid level, the ultrasonic guided wave liquid level detection system needs to be calibrated to a reference value. The specific operation method is as follows: When there is no liquid in the pipeline, the first ultrasonic guided wave signal acquisition is performed, and the peak-to-peak value of the ultrasonic guided wave signal is extracted by the host computer and recorded as the peak-to-peak value in the empty tank state; when the pipeline is filled with the liquid to be tested, the second ultrasonic guided wave signal acquisition is performed, and the peak-to-peak value of the ultrasonic guided wave signal is extracted by the host computer and recorded as the peak-to-peak value in the full tank state; at this point, the ultrasonic guided wave liquid level detection system has completed all the reference value calibrations.

[0071] Step (4): The liquid level in the pipe to be tested is detected. The specific operation method is as follows: When the liquid level in the pipe is unknown, the host computer controls the ultrasonic probe at the transmitting end to generate ultrasonic guided waves, which are received by the ultrasonic probe at the receiving end and transmitted back to the host computer to complete one ultrasonic guided wave signal acquisition. The peak-to-peak value of the ultrasonic guided wave signal at this time is recorded as the peak-to-peak value of the state to be tested. Since the ultrasonic guided wave propagating in the container wall will leak when there is liquid on one side of the container wall, the amplitude change of the ultrasonic guided wave received signal and the liquid level change are fixed when the container shape is determined. The host computer can calculate the liquid level in the pipe to be tested at this time based on the functional relationship between the peak-to-peak value of the state to be tested, the peak-to-peak value of the empty box state, and the peak-to-peak value of the full box state, as well as the fixed position of the ultrasonic probe at the transmitting end and the receiving end. Finally, the result is as follows. Figure 5 The liquid level detection results are shown.

[0072] In this embodiment, the transmitting and receiving ultrasonic probes use piezoelectric micromechanical ultrasonic transducers as sensing elements. A preferred micromechanical ultrasonic transducer array structure is as follows: Figure 5As shown, both the transmitting and receiving ultrasonic probes must maintain tight and stable contact with the outer wall of the container under test. The fixed positions of the transmitting and receiving ultrasonic probes relative to the container must be precise; their installation accuracy directly affects the detection accuracy of the ultrasonic guided wave liquid level detection system. The installation positions of the upper and lower receiving ultrasonic probes determine the measurement range of the ultrasonic guided wave liquid level detection system; liquid levels exceeding the installation positions of the upper and lower receiving ultrasonic probes cannot be measured. The functional relationship between the amplitude of the ultrasonic guided wave received signal and the liquid level will change according to the actual detection conditions such as the size of the container, the thickness of the container wall, and the material of the container wall. The functional relationship used in actual detection needs to be calculated by the host computer based on the actual liquid level detection environment. The measurement range and accuracy of this liquid level detection method can be increased by increasing the number of transmitting and receiving ultrasonic probes.

[0073] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A liquid level detection system for a spherical container based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided waves, characterized in that, Includes a spherical container (1), on which is provided a transmitting piezoelectric micromechanical ultrasonic probe (2) and a receiving piezoelectric micromechanical ultrasonic probe. The vertical height of the transmitting piezoelectric micromechanical ultrasonic probe (2) is not higher than the minimum liquid level specified in the spherical container (1). The receiving piezoelectric micromechanical ultrasonic probe is located above the transmitting piezoelectric micromechanical ultrasonic probe (2). The transmitting signal center of the transmitting piezoelectric micromechanical ultrasonic probe (2) and the receiving signal center of the receiving piezoelectric micromechanical ultrasonic probe pass through the center of the spherical container (1). The transmitting end piezoelectric micromechanical ultrasonic probe (2) is connected to an ultrasonic signal excitation module (6), the receiving end piezoelectric micromechanical ultrasonic probe is connected to a signal processing module (7), the signal processing module (7) is connected to a host computer (8), and the host computer (8) is used to calculate the liquid level in the spherical container (1) using the ultrasonic signal processed by the signal processing module (7). The receiving end piezoelectric micromechanical ultrasonic probe includes an upper receiving end piezoelectric micromechanical ultrasonic probe (3). The vertical height of the upper receiving end piezoelectric micromechanical ultrasonic probe (3) is not lower than the highest liquid level specified in the spherical container (1). The host computer (8) calculates the liquid level in the spherical container (1) according to the following formula. H : In the formula, V k 、V m The values ​​represent the peak-to-peak value of the ultrasonic guided wave received signal received by the piezoelectric micromechanical ultrasonic probe at the receiving end of the spherical container (1) in the empty state and the peak-to-peak value of the ultrasonic guided wave received signal received by the piezoelectric micromechanical ultrasonic probe at the receiving end of the spherical container (1) in the full state, respectively. V d The peak-to-peak value of the ultrasonic guided wave received signal received by the piezoelectric micromechanical ultrasonic probe (3) at the upper receiving end during the measurement of the liquid level in the spherical container (1) under the condition of the liquid level to be measured in the spherical container (1); α The angle between the line connecting the signal transmission center of the piezoelectric micromechanical ultrasonic probe (2) and the center of the spherical container (1) and the vertical axis of the spherical container (1) is given. β The angle between the line connecting the center of the upper receiving piezoelectric micromechanical ultrasonic probe (3) and the center of the spherical container (1) and the line connecting the signal transmission center of the transmitting piezoelectric micromechanical ultrasonic probe (2) and the center of the spherical container (1) on the vertical plane is given. R Let the radius of the spherical container (1) be . θ The angle between the line connecting the edge of the liquid level to be measured inside the spherical container (1) and the center of the circle and the vertical axis of the spherical container (1); Alternatively, the receiving piezoelectric micromechanical ultrasonic probe includes an upper receiving piezoelectric micromechanical ultrasonic probe (3) and a lower receiving piezoelectric micromechanical ultrasonic probe (4). The vertical height of the upper receiving piezoelectric micromechanical ultrasonic probe (3) is not lower than the highest liquid level specified in the spherical container (1), and the vertical height of the lower receiving piezoelectric micromechanical ultrasonic probe (4) is located at the midpoint between the upper receiving piezoelectric micromechanical ultrasonic probe (3) and the transmitting piezoelectric micromechanical ultrasonic probe (2). The host computer (8) calculates the liquid level in the spherical container (1) according to the following formula. H : In the formula, V k 、V m The peak-to-peak values ​​of the ultrasonic guided wave received signals received by the piezoelectric micromechanical ultrasonic probe (3) at the receiving end and the piezoelectric micromechanical ultrasonic probe (4) at the lower receiving end in the empty state of the spherical container (1) are respectively, and the peak-to-peak values ​​of the ultrasonic guided wave received signals received by the piezoelectric micromechanical ultrasonic probe (3) at the receiving end and the piezoelectric micromechanical ultrasonic probe (4) at the lower receiving end in the full state of the spherical container (1) are respectively. V 1d , V 2d The peak-to-peak values ​​of the ultrasonic guided wave received by the piezoelectric micromechanical ultrasonic probe (3) at the receiving end and the ultrasonic guided wave received by the piezoelectric micromechanical ultrasonic probe (4) at the lower receiving end are respectively represented during the measurement of the liquid level in the spherical container (1) under the liquid level to be measured. α The angle between the line connecting the signal transmission center of the piezoelectric micromechanical ultrasonic probe (2) and the center of the spherical container (1) and the vertical axis of the spherical container (1) is given. β The angle between the line connecting the center of the upper receiving piezoelectric micromechanical ultrasonic probe (3) and the center of the spherical container (1) and the line connecting the signal transmission center of the transmitting piezoelectric micromechanical ultrasonic probe (2) and the center of the spherical container (1) on the vertical plane is given. R Let the radius of the spherical container (1) be . θ The angle between the line connecting the edge of the liquid level to be measured inside the spherical container (1) and the center of the circle and the vertical axis of the spherical container (1).

2. The spherical container liquid level detection system based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided wave as described in claim 1, characterized in that, The transmitting piezoelectric micromechanical ultrasonic probe (2) and the receiving piezoelectric micromechanical ultrasonic probe (3) are both located on the circumference of the cross section passing through the center of the spherical container (1) in the vertical direction. The transmitting piezoelectric micromechanical ultrasonic probe (2) and the receiving piezoelectric micromechanical ultrasonic probe (3) are both located on the same side of the vertical axis of the spherical container (1).

3. The spherical container liquid level detection system based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided wave as described in claim 1, characterized in that, The transmitting piezoelectric micromechanical ultrasonic probe (2), the upper receiving piezoelectric micromechanical ultrasonic probe (3), and the lower receiving piezoelectric micromechanical ultrasonic probe (4) are all located on the circumference of the cross section passing through the center of the spherical container (1) in the vertical direction. The transmitting piezoelectric micromechanical ultrasonic probe (2), the upper receiving piezoelectric micromechanical ultrasonic probe (3), and the lower receiving piezoelectric micromechanical ultrasonic probe (4) are all located on the same side of the vertical axis of the spherical container (1).

4. The spherical container liquid level detection system based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided wave as described in claim 1, characterized in that, The outside of the spherical container (1) is provided with a piezoelectric micromechanical ultrasonic probe fixing device (5), and the transmitting end piezoelectric micromechanical ultrasonic probe (2) and the receiving end piezoelectric micromechanical ultrasonic probe are both set on the piezoelectric micromechanical ultrasonic probe fixing device (5).

5. The spherical container liquid level detection system based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided wave as described in claim 1, characterized in that, A coupling layer is provided between the spherical container (1) and the transmitting piezoelectric micromechanical ultrasonic probe (2) as well as between the spherical container (1) and the receiving piezoelectric micromechanical ultrasonic probe.

6. The spherical container liquid level detection system based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided wave as described in claim 1, characterized in that, The ultrasonic signal excitation module (6) and the signal processing module (7) are both connected to the host computer (8). The host computer (8) is used to control the ultrasonic signal excitation module (6) so that the piezoelectric micromechanical ultrasonic probe (2) at the transmitting end generates ultrasonic signals. The host computer (8) is also used to receive the ultrasonic signals processed by the signal processing module (7), as well as to collect and record signals, and to calculate the liquid level in the spherical container (1) using the collected signals.

7. A method for detecting the liquid level in a spherical container based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided waves, characterized in that, The liquid level detection method uses the spherical container liquid level detection system based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided wave as described in any one of claims 1-6. The liquid level detection method includes the following process: The ultrasonic signal is generated by the piezoelectric micromechanical ultrasonic probe (2) at the transmitting end controlled by the ultrasonic signal excitation module (6); the ultrasonic guided wave signal is received by the piezoelectric micromechanical ultrasonic probe at the receiving end; the signal processing module processes the ultrasonic guided wave signal received by the piezoelectric micromechanical ultrasonic probe at the receiving end; and the host computer (8) uses the ultrasonic signal processed by the signal processing module (7) to calculate the liquid level in the spherical container (1).

8. The method for detecting liquid level in a spherical container based on a piezoelectric micromechanical ultrasonic transducer and ultrasonic guided wave, as described in claim 7, is characterized in that... The signal processing module performs signal processing on the ultrasonic guided wave signal received by the piezoelectric micromechanical ultrasonic probe at the receiving end, including signal noise reduction, signal filtering, and signal amplification.

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