Compressor liquid level ultrasonic measurement system based on transverse waves

Abstract

The invention belongs to the technical field of liquid level detection, and particularly relates to a compressor liquid level ultrasonic measuring system based on transverse waves, which comprises a compressor body, a cavity wall, a transmitting ultrasonic transducer and a receiving ultrasonic transducer, the compressor body is arranged in the cavity wall, and the transmitting ultrasonic transducer and the receiving ultrasonic transducer are fixed on the outer surface of the cavity wall. And the transmitting ultrasonic transducer and the receiving ultrasonic transducer are arranged on the same side of the cavity wall. Liquid level judgment is carried out depending on the transverse waves propagating along the cavity wall, compared with a traditional longitudinal wave penetrating type measurement method, the transverse wave propagation path is stable and does not penetrate through the interior of liquid, interference of complex structures (such as a cylinder body, a valve and a lubricating pipeline) in the cavity on the sound wave propagation path can be effectively avoided, and the measurement accuracy is improved. Therefore, the accuracy of a measurement result and the anti-interference capability of the system are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid level detection, and particularly relates to a compressor liquid level ultrasonic measurement system based on shear waves. Background Art

[0002] As a core component of industrial refrigeration, gas transmission and other equipment, the normal operation of a compressor plays a decisive role in the safety and stability of the overall system. During the operation of the compressor, real-time monitoring of the lubricating oil level is crucial. An excessively high liquid level may cause liquid hammer in the cylinder, while an excessively low liquid level may result in insufficient lubrication, component wear, and even serious accidents such as compressor burnout. Therefore, developing a precise and reliable compressor liquid level measurement system has important engineering significance and application value.

[0003] To achieve non-contact monitoring of the liquid level inside the compressor cavity, ultrasonic measurement technology is commonly used in the prior art. Such systems usually set a pair of ultrasonic transducers outside the compressor cavity wall. One transducer is used to emit ultrasonic waves in the form of longitudinal waves, and the other transducer is used to receive the propagated signal. By changing the propagation characteristics of the ultrasonic signal in the liquid, the liquid level height inside the cavity is indirectly judged.

[0004] Although the non-contact ultrasonic liquid level measurement technology based on longitudinal waves has the advantages of not requiring contact with the liquid, simple installation, and being applicable to sealed cavities, when longitudinal waves propagate in solid media, they are easily interfered by reflections, refractions, and scatterings from complex structures inside the cavity wall (such as cylinder blocks, brackets, pipelines, etc.), resulting in unstable acoustic wave paths and overlapping echo signals, thus affecting the accuracy of liquid level identification. Summary of the Invention

[0005] To solve the above problems, the present invention provides a compressor liquid level ultrasonic measurement system based on shear waves, including a compressor body, a cavity wall, a transmitting ultrasonic transducer, and a receiving ultrasonic transducer. The compressor body is placed inside the cavity wall, and the transmitting ultrasonic transducer and the receiving ultrasonic transducer are fixed on the outer surface of the cavity wall. In particular, the transmitting ultrasonic transducer and the receiving ultrasonic transducer are placed on the same side of the cavity wall.

[0006] In the present invention, when the transmitting ultrasonic transducer operates, it simultaneously excites longitudinal waves and transverse waves. The longitudinal waves propagate in the vertical direction, pass through the cavity wall and enter the interior of the compressor cavity. At the liquid interface, reflection occurs, but the reflected longitudinal waves will not be received by the receiving ultrasonic transducer, so they do not participate in the measurement process. At the same time, the excited transverse waves propagate in the direction parallel to the cavity wall, especially along the path near the inner surface of the cavity wall to the receiving ultrasonic transducer. Since the contact interface between the inner surface of the cavity wall and the liquid changes with the change of the liquid level, when the transverse waves pass through the regions corresponding to different liquid level heights during propagation, the energy transmission will be affected by the change of the interface acoustic impedance, resulting in different propagation losses. The liquid-covered area usually causes absorption or scattering of the transverse wave energy, thus changing the intensity of the transverse wave signal reaching the receiving ultrasonic transducer. By detecting the change in the strength of the transverse wave signal, non-contact and precise measurement of the liquid level in the compressor cavity can be achieved.

[0007] Furthermore, the transmitting ultrasonic transducer is placed directly below the receiving ultrasonic transducer, which helps the transverse waves to propagate stably in the vertical direction in the cavity wall, forming a relatively simple and linear propagation path. This up-and-down arrangement not only reduces the path deflection and multiple reflections of the transverse waves during propagation in the cavity wall, but also improves the energy transmission efficiency and enhances the consistency and repeatability of the signals. At the same time, since the change of the liquid level occurs in the vertical direction, this arrangement makes the propagation path of the transverse waves perpendicular to the direction of the liquid level change, which is beneficial to enhancing the modulation effect of the interface state change on the transverse wave energy loss, thereby improving the sensitivity and resolution of the liquid level measurement.

[0008] Furthermore, it also includes a first fixing part and a second fixing part. The first fixing part is arranged between the transmitting ultrasonic transducer and the cavity wall, and the second fixing part is arranged between the receiving ultrasonic transducer and the cavity wall. The first fixing part and the second fixing part provide a stable mechanical connection, which helps to maintain a good coupling state among the transmitting ultrasonic transducer, the receiving ultrasonic transducer and the cavity wall, and improves the excitation and reception efficiency of ultrasonic waves. In addition, the first fixing part and the second fixing part can also play the roles of vibration isolation, buffering and thermal insulation, reducing the interference of the vibration and high temperature during the operation of the compressor on the ultrasonic signals, and further improving the stability and reliability of the system measurement.

[0009] Furthermore, the first fixing part and the second fixing part are trapezoidal. The inclined surface of the first fixing part faces the receiving ultrasonic transducer, and the inclined surface of the second fixing part faces the transmitting ultrasonic transducer. The upper inclined surface of the first fixing part helps to direct the shear wave excited by the transmitting ultrasonic transducer towards the receiving ultrasonic transducer, reducing the divergence of the initial beam; while the inclined surface of the second fixing part faces the transmitting ultrasonic transducer, which can play a role in beam convergence or suppressing reflection interference when the shear wave reaches the receiving end. Overall, this structure forms a geometric profile of an "acoustic wave channel", enabling the shear wave to propagate in the cavity wall in a more stable, concentrated and efficient path, enhancing the transmission efficiency and reception consistency of the shear wave energy, thereby improving the measurement sensitivity and anti-interference ability of the system.

[0010] Furthermore, it also includes micro-grooves. The micro-grooves are arranged horizontally. There are multiple micro-grooves, and the multiple micro-grooves are arranged between the transmitting ultrasonic transducer and the receiving ultrasonic transducer on the inner surface of the cavity wall. By introducing periodic microstructural perturbations into the shear wave propagation path, the interaction between the shear wave and the liquid interface is effectively enhanced. When the liquid level change covers different numbers of micro-groove areas, the energy loss, scattering or phase change of the shear wave during propagation also changes accordingly, making the shear wave signal more sensitive to small fluctuations in the liquid level. At the same time, the horizontal arrangement direction of the micro-grooves is perpendicular to the liquid level change direction, which is conducive to "mapping" the change in the liquid level height into the "structural difference" on the shear wave propagation path, significantly improving the spatial resolution and response sensitivity of the liquid level measurement, and enhancing the system's perception ability to the liquid level change.

[0011] Furthermore, the cross-section of the micro-groove is V-shaped. Compared with rectangular or U-shaped grooves, the V-shaped micro-groove has stronger acoustic energy perturbation and coupling modulation ability during the shear wave propagation. The sharp structure of the V-shaped groove can form obvious stress concentration areas in the shear wave propagation path, enhancing the local scattering and attenuation effects; when the liquid level covers or leaves these V-shaped grooves, the energy loss of the shear wave caused by the change in the interface acoustic impedance is more significant, making the intensity of the received signal more sensitively respond to small changes in the liquid level. In addition, the wedge-shaped structure of the V-shaped groove is convenient for manufacturing deeper incisions, improving the modulation depth without significantly increasing the processing width, which helps to amplify the influence of the liquid level change on the shear wave propagation characteristics and further improve the measurement sensitivity and resolution of the system.

[0012] Furthermore, it also includes a damping part, which is fixed between the ultrasonic transducer and the receiving transducer on the outer surface of the cavity wall. The damping part can be made of high-loss flexible materials such as rubber, polyurethane or foam materials, which have good vibration absorption ability and can convert part of the energy into heat energy dissipation when the shear wave propagates to its position, thus significantly suppressing the multiple reflections and crosstalk effects of the sound wave on the outer surface. By directionally controlling the sound field outside the cavity wall, the damping part helps to enhance the response signal-to-noise ratio of the system to the shear wave propagating on the inner surface of the cavity wall, improving the accuracy, stability and anti-interference ability of the liquid level measurement, especially suitable for high-precision liquid level detection scenarios under complex working conditions.

[0013] Furthermore, inserts are provided in the damping part, and the Young's modulus of the inserts is greater than that of the damping part. The inserts with high Young's modulus can form a strong reflection interface when the shear wave enters the damping part, suppressing the continuous propagation of sound energy along the outer surface; while the damping matrix with low modulus further absorbs the remaining energy, forming a double damping mechanism. This structure can not only reflect part of the shear wave energy but also dissipate the remaining fluctuations, significantly improving the suppression efficiency of the shear wave on the outer surface of the cavity wall, reducing the interference of external noise on the received signal, and thus improving the stability of the liquid level measurement and the anti-interference ability of the system.

[0014] Furthermore, the inserts are cylindrical, and the height direction of the inserts is the normal direction of the cavity wall. The cylindrical inserts form periodically or discretely distributed high-stiffness regions on the shear wave propagation path, causing the sound wave to undergo strong reflection, scattering or mode conversion when encountering these vertical rigid columns, thereby reducing the long-distance transmission efficiency of the sound energy. At the same time, since the columns are arranged along the normal direction of the cavity wall, which is orthogonal to the propagation direction of the shear wave surface wave, the propagation continuity of the shear wave can be disrupted to the maximum extent, effectively enhancing the isolation ability of the damping part to the shear wave. This design not only enhances the shielding effect on the interference wave but also helps to improve the purity of the received signal and the signal-to-noise ratio of the measurement system.

[0015] Furthermore, it also includes a refrigeration part, which is connected to the inserts. When the compressor operates, the temperature inside the cavity is relatively high, which easily causes thermal expansion of the cavity wall, reduction of the material elastic modulus and change of the acoustic impedance, thus causing adverse effects such as bending of the shear wave path and enhanced scattering. The setting of the refrigeration part can slow down the temperature difference from the inside to the outside of the cavity wall, keep the physical properties of the shear wave propagation medium relatively stable, and improve the propagation consistency and directionality of the shear wave along the inner surface of the cavity wall. At the same time, cooling the inserts can also enhance their reflection ability to the shear wave, further suppressing the transmission of external interference waves, and helping to improve the liquid level detection accuracy, signal stability and measurement reliability of the system in high-temperature environments.

[0016] Advantages of the present invention: (1) The present invention adopts a structural design in which an ultrasonic transducer is installed on the outside of the compressor cavity wall, thereby realizing non-contact measurement of the liquid level in the cavity. There is no need to destroy the sealing of the cavity, nor is there a need to set up a sensor element inside the compressor. The present invention is particularly suitable for liquid level monitoring of sealed compressors in industrial environments such as high pressure, high temperature, and prone to leakage, effectively improving the safety and reliability of the system.

[0017] (2) The present invention relies on the shear waves propagating along the cavity wall to judge the liquid level. Compared with the traditional longitudinal wave penetration measurement method, the shear wave propagation path is stable and does not pass through the interior of the liquid. It can effectively avoid the interference of complex structures in the cavity (such as cylinder body, valve parts, lubrication pipes, etc.) on the sound wave propagation path, thereby improving the accuracy of the measurement results and the anti-interference ability of the system.

[0018] (3) The present invention utilizes the modulation effect of liquid level changes on the acoustic impedance of the cavity wall interface to achieve a highly sensitive response to the intensity of the shear wave signal. By accurately detecting the slight changes in the shear wave signal, high-resolution liquid level recognition can be achieved, meeting the refined needs of liquid level change monitoring.

[0019] (4) The present invention only requires a pair of ultrasonic transducers to be arranged outside the compressor cavity wall, without modifying the internal structure of the compressor. The overall system structure is simple and easy to integrate or modify in new equipment and existing equipment. At the same time, since the sensor element is located outside the equipment, the subsequent maintenance, calibration and replacement operations are simple, which significantly reduces the system operation and maintenance costs.

[0020] In summary of the above beneficial effects, the present invention has good application prospects in the field of compressor liquid level measurement technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of a compressor liquid level ultrasonic measurement system based on shear waves.

[0022] Figure 2 Schematic diagram of another compressor liquid level ultrasonic measurement system based on shear waves.

[0023] Figure 3 Schematic diagram of another compressor liquid level ultrasonic measurement system based on shear waves.

[0024] Figure 4 Schematic diagram of the damping unit.

[0025] In the figure: 1, cavity wall; 2, transmitting ultrasonic transducer; 3, receiving ultrasonic transducer; 4, first fixing part; 5, second fixing part; 6, damping part; 61, insert. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of this application more clear and understandable, the following provides further detailed descriptions of this application with reference to the accompanying drawings and by way of examples.

[0027] Embodiment 1 This embodiment provides a compressor liquid level ultrasonic measurement system based on shear waves. As Figure 1 shown, it includes a compressor body, a cavity wall 1, a transmitting ultrasonic transducer 2, and a receiving ultrasonic transducer 3.

[0028] It should be noted that generally, the cavity wall 1 is part of the compressor. For the convenience of description, in this invention, the cavity wall 1 is separated and described independently.

[0029] The compressor body is a vertical closed structure, using a high-pressure-resistant cast aluminum housing, which is used to compress and store refrigerant and lubricating oil inside. The cavity wall 1 is the metal outer shell part of this compressor body, and 304 stainless steel plates with a thickness of 8 mm are selected. Both the transmitting ultrasonic transducer 2 and the receiving ultrasonic transducer 3 are fixedly installed on the same side of the outer surface of the cavity wall 1, and are specifically fixed by means of coupling threads + thermal conductive silicone to ensure the close contact between the transducer and the metal cavity wall 1 and the acoustic energy coupling efficiency. Among them, the transmitting ultrasonic transducer 2 selects a high-frequency shear wave piezoelectric transducer with the model Airmar PZT-SW150-5T, with a working frequency of 5 MHz, a diameter of φ10 mm, a thickness of 5 mm, the housing is coated with aluminum alloy, and a conical waveguide head is provided at the bottom. The receiving ultrasonic transducer 3 selects a shear wave receiver of the Olympus V151 series, with a center frequency of 5 MHz and the same size of φ10mm×5 mm. The transmitting transducer 2 is installed directly below the receiving transducer 3, and the central axes of the two are collinear, with a vertical distance of 40 mm, forming a vertical shear wave propagation path, and the shear wave propagates upward along the inner surface of the cavity wall 1 in the form of a surface wave to the receiving transducer 3.

[0030] When the transmitting transducer 2 works, it excites an ultrasonic shear wave in the shear mode, and the shear wave propagates in the form of a surface wave or a plate wave within the thickness range of the cavity wall 1. Since the energy of the shear wave is mainly distributed in the area near the inner surface of the cavity wall, whether the propagation path is covered by liquid will significantly affect its energy attenuation degree and phase characteristics.

[0031] In this embodiment, during the operation of the compressor, the height of the lubricating oil liquid level changes at any time. After the liquid contacts the inner surface of the cavity wall 1, it changes the acoustic impedance characteristics at this place, causing part of the shear wave energy to be absorbed or scattered here. The signal intensity received by the receiving transducer 3 fluctuates accordingly due to the liquid level change, and through the dynamic change of the signal intensity, the quantitative inversion of the liquid level height can be realized.

[0032] The advantages of this system are as follows: no need to set any sensing elements inside the cavity; the shear wave propagation path does not penetrate the liquid, with high signal stability; the structure is compact and suitable for external integration with existing compressors.

[0033] Embodiment 2 Based on Embodiment 1, as Figure 2 shown, this embodiment further includes a first fixing part 4 and a second fixing part 5. The first fixing part 4 is arranged between the transmitting ultrasonic transducer 2 and the cavity wall 1, and the second fixing part 5 is arranged between the receiving ultrasonic transducer 3 and the cavity wall 1. Both are fixed on the outer surface of the cavity wall 1 and are on the same straight axis in the vertical direction.

[0034] Both the first fixing part 4 and the second fixing part 5 are trapezoidal structural blocks, in the shape of a right trapezoid, with structural dimensions: the upper base is 8 mm, the lower base is 10 mm, and the inclined surface inclination angle is 30°. The inclined surface of the first fixing part 4 faces the receiving ultrasonic transducer 3 and is used to conduct the shear wave energy excited at the transmitting end upward; the inclined surface of the second fixing part 5 faces the transmitting ultrasonic transducer 2, which is beneficial for the receiving end to focus the shear wave beam from the direction of the transmitting end and enhance the coupling efficiency.

[0035] The materials of the first fixing part 4 and the second fixing part 5 are selected as aluminum alloy 6061-T6, with a Young's modulus of about 69 GPa and a density of 2.7 g / cm³. To enhance corrosion resistance and thermal stability, the surfaces of the fixing parts are treated by anodic oxidation. A layer of thermally conductive acoustic coupling glue (such as 3M TC-2810) is respectively applied between the first fixing part 4 (the second fixing part 5) and the cavity wall 1, and between the first fixing part (the second fixing part) and the transmitting ultrasonic transducer (the receiving ultrasonic transducer) to reduce the acoustic impedance jump and improve the energy transmission efficiency of the shear wave.

[0036] The symmetric layout design of the first fixing part 4 and the second fixing part 5 forms a "geometric acoustic channel" between the transmitting and receiving transducers, enabling the shear wave to form a stable and clearly defined propagation path along the inner surface of the cavity wall. This structure significantly suppresses the scattering and deviation of the shear wave caused by factors such as cavity wall deformation and local unevenness, enhances the propagation consistency of the shear wave under the modulation of the liquid level interface, and thus improves the sensitivity and repeatability of the system for liquid level measurement.

[0037] In addition, the first fixing part 4 and the second fixing part 5 also play a role in mechanical vibration isolation. The trapezoidal structure itself has certain structural damping characteristics, and together with the buffering effect of the coupling glue, the transmitting ultrasonic transducer 2 and the receiving ultrasonic transducer 3 can still maintain a good fitting state under the vibration conditions during the operation of the compressor, preventing the signal waveform from fluctuating due to micro-displacement and further improving the signal stability and system reliability.

[0038] In summary, in this embodiment, by introducing the trapezoidal first fixing part 4 and the second fixing part 5 with symmetrical orientations, not only the excitation and reception paths of shear waves are optimized, but also the structural adaptability and measurement accuracy of the ultrasonic system in high-temperature and high-vibration environments are improved, which is particularly suitable for the key application scenarios of industrial compressor liquid level monitoring.

[0039] Embodiment 3 Based on Embodiment 1 or 2, this embodiment further includes a plurality of micro-groove structures for enhancing the shear wave's ability to sense liquid level changes. The micro-grooves are arranged horizontally and evenly distributed on the inner surface of the cavity wall 1, specifically between the regions corresponding to the transmitting ultrasonic transducer 2 and the receiving ultrasonic transducer 3. This region is the main path for shear waves to propagate along the cavity wall 1, so the setting position of the micro-grooves highly coincides with the shear wave energy distribution area.

[0040] The length direction of each micro-groove extends horizontally and is orthogonal to the vertical change direction of the liquid level. This enables the liquid level to gradually cover or expose different numbers of micro-grooves when rising or falling, thereby changing the boundary conditions in the shear wave propagation path and causing perceivable signal intensity changes, enhancing the spatial resolution and sensitivity of the liquid level detection system.

[0041] The cross-sectional shape of the micro-groove is V-shaped, presenting an acute-angle wedge structure. Compared with rectangular or U-shaped grooves, the V-shaped design can generate stronger stress concentration and scattering effects during the propagation of shear waves, thereby enhancing the shear wave's response ability to changes in the cavity wall surface state. The opening width of each V-shaped groove is 1 mm, the groove depth is 0.8 mm, and the bottom angle of the groove is 60°. These are parameter configurations optimized through acoustic field simulation, taking into account both enhanced scattering and machining feasibility.

[0042] The micro-grooves are precisely etched on the inner surface of the cavity wall 1 through a laser engraving process and are suitable for stainless steel materials. The cavity wall 1 is made of 304 stainless steel with a thickness of 8 mm, having good mechanical stability and shear wave propagation ability. At the same time, its metal surface has sufficient hardness to withstand the local thermal shock during the micro-groove processing.

[0043] The spacing between the micro-grooves is 5 mm, and they are arranged continuously in the vertical direction. A total of 12 grooves are arranged, with a total coverage height of 55 mm, corresponding to the conventional liquid level change range of the compressor. Each groove is kept strictly parallel to prevent mode coupling and aliasing of shear waves during propagation, ensuring that each level change in the liquid level can cause distinguishable energy attenuation differences.

[0044] The presence of microgrooves introduces controllable periodic structural disturbances on the inner surface of the cavity wall, forming local modulation of the shear wave propagation path. When the liquid level rises to cover more microgrooved areas, the liquid and the V-groove form a composite boundary, which will lead to an increase in the sudden change of acoustic impedance and an increase in the shear wave energy attenuation, thereby significantly reducing the signal strength received by the receiving ultrasonic transducer 3. By analyzing the amplitude changes of the received signal, high-precision, segmented inversion of the liquid level height can be achieved.

[0045] In summary, this embodiment significantly enhances the modulation capability of the shear wave propagation path to the liquid level change by setting a plurality of horizontal V-shaped microgrooves on the inner surface of the cavity wall 1, thereby improving the sensitivity, resolution and anti-interference capability of the system, and is particularly suitable for compressor systems that require precise liquid level control under complex working conditions.

[0046] Example 4 On the basis of Embodiments 1 to 3, this embodiment further includes a damping portion 6, which is fixed on the outer surface of the cavity wall 1, located between the transmitting ultrasonic transducer 2 and the receiving ultrasonic transducer 3, and is located in the corresponding outer area on the shear wave propagation path. This structure is used to absorb and weaken the shear wave propagating along the outer surface of the cavity wall, prevent it from interfering with the received signal, and improve the system's ability to resolve the inner surface shear wave signal.

[0047] The damping part 6 is made of a high molecular weight polyurethane foam rubber material with a Young's modulus of about 3 MPa, a thickness of 10 mm, and a length of 50 mm, covering most of the outer surface area between the transmitting ultrasonic transducer 2 and the receiving ultrasonic transducer 3. The material has good flexibility and high internal friction characteristics, can effectively absorb medium and high frequency shear wave energy, and play a damping and attenuation role.

[0048] To further enhance the damping effect, multiple inserts 61 are embedded inside the damping part 6. The insert 61 is a rigid cylindrical structure, and the material is stainless steel 304, whose Young's modulus is about 200 GPa, much higher than the polyurethane matrix material. The diameter of the insert 5 is 3 mm, and the height is 10 mm. Its axial direction (height direction) is consistent with the normal direction of the cavity wall 1, that is, it is embedded perpendicular to the cavity wall surface, and the top is slightly higher than the surface of the damping part 6.

[0049] The cylindrical inserts 61 are arranged at equal intervals in the damping part 6, with a center spacing of 10 mm, forming a periodic structural array. When the shear wave propagates along the outer surface of the cavity wall to the damping area, it will encounter the acoustic impedance mutation and interface reflection of multiple vertical inserts 61, resulting in energy splitting and scattering, and most of the sound energy is rebounded back to the cavity wall 1 or absorbed by the damping material. This structure essentially forms a local composite bandgap damping layer, which can significantly inhibit the propagation of shear wave energy along the outer surface and prevent it from diffracting through the wall or structural support to the receiving end.

[0050] In addition, since the direction of the cylindrical insert 61 is orthogonal to the direction of the transverse wave propagation, it forms a high-reflection surface locally, interrupting the continuous propagation path at the structural level. At the same time, it also increases the damping ability of the damping part 6 to suppress the vibration of the external structure, which is beneficial to improving the anti-vibration stability of the overall system.

[0051] The damping part 6 is bonded to the outer surface of the cavity wall 1 by an industrial adhesive with high bonding strength (such as Loctite 480) and can be disassembled for maintenance. The overall structure is reasonably arranged and the processing technology is mature, which is suitable for working stably in the high-temperature and high-vibration environment during the operation of industrial compressor equipment for a long time.

[0052] Embodiment 5 On the basis of Embodiment 4, this embodiment further includes a refrigeration part for actively cooling the insert 61 in the damping part 6 and the outer surface of the cavity wall 1. The refrigeration part is thermally connected to the cylindrical insert 61 with a high Young's modulus to achieve heat conduction and regional temperature reduction. The purpose is to reduce the temperature gradient fluctuation on the outer surface of the cavity wall 1 and improve the propagation stability and signal-to-noise ratio of the transverse wave under high-temperature operating conditions.

[0053] The refrigeration part is arranged on the outside of the damping part 6 and is in close contact with the outer end face of the insert 61 to form a thermal contact coupling interface. In this embodiment, 3 mm is reserved at the upper end of the insert 61 to protrude from the surface of the damping part to form a heat transfer interface with the refrigeration module, and the interface is coated with thermal conductive silicone grease (such as ARCTIC MX-4) to reduce the thermal resistance.

[0054] The refrigeration part is a thermoelectric refrigeration component (TEC module). The Peltier thermoelectric chip with the model of TEC1-12706 is selected, with a working voltage of 12V, a refrigeration power of 60W, a size of 40 mm×40 mm×3.5 mm. The bottom surface is pressed against the top of all inserts through a heat-conducting copper plate to achieve multi-point parallel cooling. The hot end is connected with an aluminum fin-type radiator and a silent fan for forced air convection heat dissipation to ensure the continuous and efficient operation of the thermoelectric component.

[0055] For structural fixation, the refrigeration part is fastened above the damping part 6 through a stainless steel pressing plate + spring screws. The pressing plate is provided with a plurality of round holes for precise alignment with the cylindrical insert 61 to ensure good coupling thermodynamically and no disturbance structurally. The outside of the pressing plate is provided with a polyurethane buffer cushion layer to isolate mechanical vibration.

[0056] By cooling the insert 61 and the outer surface of the cavity wall 1, the acoustic impedance gradient caused by the internal and external temperature difference is reduced, avoiding non-linear effects such as the bending of the shear wave propagation path, the change in velocity, and the fluctuation of the attenuation rate. The decrease in temperature increases the elastic modulus and reduces the damping of the metal cavity wall 1, which helps to keep the shear wave waveform clear and the propagation direction stable, effectively improving the signal consistency. In addition, the hardness and acoustic impedance of the cooled cylindrical insert 61 are relatively enhanced, which is beneficial to enhancing its reflection performance for shear waves and further weakening the possibility of interference waves propagating on the outer surface of the cavity wall.

[0057] In this embodiment, the refrigeration unit adopts a modular design, and multiple thermoelectric refrigeration units can be added according to different application scenarios, or it can be replaced with a fluid cooling method (such as a water-cooled plate) to adapt to extremely high-temperature environments, with good expandability and maintainability.

[0058] In summary, the present invention provides a compressor liquid level ultrasonic measurement system based on shear waves. By arranging a transmitting ultrasonic transducer 2 and a receiving ultrasonic transducer 3 on the outer surface of the compressor cavity wall 1 and making the shear wave propagate along the inner surface of the cavity wall 1, non-contact and accurate measurement of the liquid level inside the compressor is achieved. The system further introduces a trapezoidal first fixing part 4 and a second fixing part 5 to optimize the shear wave propagation path, sets a microgroove structure to enhance the modulation response of the liquid level to the shear wave signal, and suppresses the shear wave interference on the outer surface through the damping part 6 and the high-modulus cylindrical insert 61. At the same time, the refrigeration part is combined to reduce the influence of thermal disturbance on the sound field stability. The overall system structure is compact, has a high signal-to-noise ratio and strong sensitivity, is suitable for the liquid level monitoring scenario of industrial compressors with high temperature, high pressure and strong sealing performance, and has broad engineering application prospects.

[0059] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the scope of protection of the present application.

Claims

1. An ultrasonic measurement system for the liquid level of a compressor based on shear waves, comprising a compressor body, a cavity wall, a transmitting ultrasonic transducer, and a receiving ultrasonic transducer. The compressor body is placed inside the cavity wall, and the transmitting ultrasonic transducer and the receiving ultrasonic transducer are fixed on the outer surface of the cavity wall. It is characterized in that: The transmitting ultrasonic transducer and the receiving ultrasonic transducer are placed on the same side of the cavity wall.

2. The ultrasonic measurement system for compressor liquid level based on shear waves according to claim 1, wherein: The transmitting ultrasonic transducer is placed directly below the receiving ultrasonic transducer.

3. The ultrasonic measurement system for compressor liquid level based on shear waves according to claim 2, characterized in that: It further includes a first fixing part and a second fixing part. The first fixing part is arranged between the transmitting ultrasonic transducer and the cavity wall, and the second fixing part is arranged between the receiving ultrasonic transducer and the cavity wall.

4. The ultrasonic measurement system for compressor liquid level based on shear waves according to claim 3, characterized in that: The first fixing part and the second fixing part are trapezoidal. The inclined surface of the first fixing part faces the receiving ultrasonic transducer, and the inclined surface of the second fixing part faces the transmitting ultrasonic transducer.

5. The ultrasonic measurement system for compressor liquid level based on shear waves according to claim 1, wherein: It further includes micro-grooves. The micro-grooves are arranged horizontally. There are multiple micro-grooves, and the multiple micro-grooves are arranged on the inner surface of the cavity wall between the transmitting ultrasonic transducer and the receiving ultrasonic transducer.

6. The ultrasonic measurement system for compressor liquid level based on shear waves according to claim 5, wherein: The cross-section of the micro-groove is V-shaped.

7. The ultrasonic measurement system for compressor liquid level based on shear waves according to any one of claims 1-6, characterized in that: It further includes a damping part. The damping part is fixed on the outer surface of the cavity wall between the transmitting ultrasonic transducer and the receiving transducer.

8. The ultrasonic measurement system for compressor liquid level based on shear waves according to claim 7, characterized in that: An insert is provided in the damping part, and the Young's modulus of the insert is greater than that of the damping part.

9. The ultrasonic measurement system for compressor liquid level based on shear wave according to claim 8, characterized in that: The insert is cylindrical, and the height direction of the insert is the normal direction of the cavity wall.

10. The ultrasonic measurement system for compressor liquid level based on shear waves as claimed in claim 9, wherein: It further includes a refrigeration part, and the refrigeration part is connected to the insert.

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