An ultrasonic sensor

Abstract

The utility model provides a kind of ultrasonic sensor, second matching layer is integrated with piezoelectric ceramic in the accommodating space of first matching layer, form integrated packaging structure, i. e. first matching layer is used as the shell of ultrasonic sensor, also as matching layer, eliminate the acoustic wave reflection interface between the shell of traditional ultrasonic sensor and matching layer, make sound energy transmission efficiency significantly improve;At the same time, the inner wall of accommodating space and second matching layer directly abut, reduce the acoustic impedance mismatch problem between multilayer medium, reduce liquid-sensor interface echo loss, improve the signal-to-noise ratio of flow detection signal;Use 0-3 type composite piezoelectric ceramic, the composite structure of its polymer matrix and piezoelectric ceramic particle can widen sensor operating bandwidth, have lower QM value and faster response rate, eliminate the pulse broadening problem caused by the QM value of traditional PZT piezoelectric ceramic in liquid medium is too high, further improve detection precision.

Description

Technical Field

[0001] This utility model belongs to the field of flow detection technology, specifically relating to an ultrasonic sensor. Background Technology

[0002] Flow measurement has a wide range of applications in industrial and consumer sectors. Compared to traditional mechanical sensors, ultrasonic flow meters offer advantages such as high measurement accuracy, good stability, wide rangeability, no mechanical parts, low pressure loss, and easy installation, gradually becoming the mainstream in the market. Ultrasonic sensors also play a crucial role in the field of liquid flow measurement.

[0003] Ultrasonic sensors are the core components of ultrasonic flow meters, and their performance directly affects the accuracy of measurement. In existing technologies, ultrasonic sensors used for liquid flow detection often consist of a housing, piezoelectric ceramic, and a matching layer. For example, patent application number 202211607987.4 discloses an ultrasonic sensor including a plastic housing, a piezoelectric ceramic sheet, and a matching layer. The piezoelectric ceramic sheet is connected to the matching layer, and the plastic housing is connected to the matching layer. The piezoelectric ceramic sheet, the plastic housing, and the matching layer are joined together as a whole during the curing process of the matching layer.

[0004] However, due to the significant difference in acoustic impedance between liquids and gases, when traditional ultrasonic sensors are used for liquid flow detection, the change and difference in acoustic impedance often lead to a decrease in ultrasonic transmittance, reducing the acoustic efficiency of the ultrasonic sensor and thus affecting the detection accuracy. Utility Model Content

[0005] To address the technical problem in the background art where traditional ultrasonic sensors used for liquid flow detection often suffer from reduced ultrasonic transmittance due to differences in acoustic impedance, thus lowering the acoustic efficiency of the ultrasonic sensor and affecting detection accuracy, this utility model provides an ultrasonic sensor.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An ultrasonic sensor for liquid flow detection includes: a first matching layer, a second matching layer, and a piezoelectric ceramic; wherein,

[0008] The first matching layer has a accommodating space;

[0009] The piezoelectric ceramic and the second matching layer are concentrically stacked in the receiving space along the ultrasonic wave transmission direction, and the second matching layer abuts against the inner wall of the receiving space, and the piezoelectric ceramic abuts against the second matching layer.

[0010] Furthermore, the piezoelectric ceramic is a 0-3 type composite piezoelectric ceramic.

[0011] Optionally, the ultrasonic sensor further includes a backing layer, which is stacked on the piezoelectric ceramic in the opposite direction of ultrasonic wave transmission and is concentric with the piezoelectric ceramic, and the backing layer is fixedly connected within the receiving space.

[0012] Optionally, the ultrasonic sensor further includes a connecting wire assembly, one end of which extends into the receiving space and is electrically connected to the piezoelectric ceramic, and the other end of which is electrically connected to an external electronic processing system.

[0013] Optionally, the connecting wire assembly includes a shielding section and a conductor section;

[0014] One end of the shielding section is electrically connected to an external electronic processing system, and the other end extends into the accommodating space;

[0015] The conductor segment includes a first conductor and a second conductor, which are electrically connected to corresponding sides of the piezoelectric ceramic, and both the first conductor and the second conductor are electrically connected to the shielding segment.

[0016] Optionally, the conductor segment is a bare wire.

[0017] Optionally, there is a gap between the backing layer and the inner wall of the receiving space, through which both the first wire and the second wire pass and are electrically connected to the piezoelectric ceramic.

[0018] Optionally, the first matching layer includes a shell and a support portion;

[0019] The shell portion and the supporting portion enclose the receiving space, and the second matching layer abuts against the supporting portion.

[0020] Optionally, the thickness of the support portion is greater than the thickness of the second matching layer.

[0021] Optionally, an anti-corrosion coating is provided on the outer side of the first matching layer.

[0022] Optionally, a bonding layer is provided between the second matching layer and the sidewall of the receiving space.

[0023] The beneficial effects of this utility model are:

[0024] This invention provides an ultrasonic sensor that integrates a second matching layer and piezoelectric ceramic within the accommodating space of the first matching layer, forming an integrated encapsulation structure. The first matching layer serves as both the ultrasonic sensor housing and the matching layer, eliminating the acoustic wave reflection interface between the housing and matching layer in traditional ultrasonic sensors, thus significantly improving acoustic energy transmission efficiency. Simultaneously, the inner wall of the accommodating space directly abuts against the second matching layer, reducing acoustic impedance mismatch between multiple media, minimizing return loss at the liquid-sensor interface, and improving the signal-to-noise ratio of the flow detection signal. The use of 0-3 type composite piezoelectric ceramic, with its composite structure of polymer matrix and piezoelectric ceramic particles, broadens the sensor's operating bandwidth, resulting in a lower QM value and faster response rate. This eliminates the pulse broadening problem caused by excessively high QM values ​​in traditional PZT piezoelectric ceramics in liquid media, further improving detection accuracy and solving the problems of decreased ultrasonic transmittance and detection accuracy in existing ultrasonic sensors used for liquid flow detection. Attached Figure Description

[0025] Figure 1 This is a cross-sectional schematic diagram of the ultrasonic sensor in this utility model;

[0026] Figure 2 This is a further cross-sectional schematic diagram of the ultrasonic sensor in this utility model;

[0027] Figure 3 This is a schematic diagram of the ultrasonic sensor in this utility model;

[0028] Figure 4 This is a top view of the ultrasonic sensor in this utility model.

[0029] Wherein: 1. First matching layer; 11. Accommodating space; 12. Shell; 13. Bearing part; 2. Second matching layer; 3. Piezoelectric ceramic; 4. Backing layer; 5. Connecting wire group; 51. Shielding section; 52. Conductor section; 521. First conductor; 522. Second conductor. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this utility model or its application or use. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0033] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this utility model.

[0034] It should be noted that, where there is no conflict, the embodiments and features in the embodiments of this utility model can be combined with each other. The present utility model will now be described in detail with reference to the accompanying drawings and embodiments.

[0035] See Figures 1 to 3 The diagram shows a schematic of an ultrasonic sensor according to the present invention. The ultrasonic sensor is used for liquid flow detection and includes: a first matching layer 1, a second matching layer 2, and a piezoelectric ceramic 3. The first matching layer 1 has a receiving space 11. The piezoelectric ceramic 3 and the second matching layer 2 are concentrically stacked in the receiving space 11 along the ultrasonic transmission direction, and the second matching layer 2 abuts against the inner wall of the receiving space 11, and the piezoelectric ceramic 3 abuts against the second matching layer 2. The piezoelectric ceramic 3 is a 0-3 type composite piezoelectric ceramic.

[0036] In this embodiment, the second matching layer 2 and the piezoelectric ceramic 3 are integrated within the accommodating space 11 of the first matching layer 1 to form an integrated encapsulation structure. The first matching layer 1 is directly used as the shell of the ultrasonic sensor and also as a matching layer, eliminating the acoustic wave reflection interface between the shell and the matching layer of the traditional ultrasonic sensor, thus significantly improving the acoustic energy transmission efficiency. At the same time, the inner wall of the accommodating space 11 directly abuts against the second matching layer 2, reducing the acoustic impedance mismatch problem between the multilayer media, reducing the return loss at the liquid-sensor interface, and improving the signal-to-noise ratio of the flow detection signal. The use of 0-3 type composite piezoelectric ceramic, whose composite structure of polymer matrix and piezoelectric ceramic particles can broaden the sensor's operating bandwidth, has a lower QM value and a faster response rate, eliminates the pulse broadening problem caused by the excessively high QM value of traditional PZT piezoelectric ceramic in liquid media, further improves the detection accuracy, and solves the problems of decreased ultrasonic transmittance and decreased detection accuracy when traditional ultrasonic sensors are used for liquid flow detection in the prior art.

[0037] Furthermore, in this embodiment, the first matching layer 1 can be made of a lightweight polymer material; specifically, the lightweight polymer material can be a foaming material, a composite material composed of hollow glass microspheres and epoxy resin, or a high-viscosity thermosetting epoxy resin; the second matching layer 2 is made of a dense polymer material, specifically, the dense polymer material is a thermosetting epoxy resin.

[0038] Furthermore, the housings of traditional ultrasonic sensors are mostly made of plastic or metal, serving only as protection or encapsulation. In this application, the first matching layer is a plastic housing with modified acoustic impedance achieved by doping with glass fiber, which serves the dual function of acoustic matching layer and protective encapsulation. Specifically, the acoustic impedance of commonly used plastic housings is around 3.4 MRayl. In this application, after modification, the acoustic impedance of the first matching layer is above 4.1 MRayl. The supplier can be Celanese.

[0039] Furthermore, the 0-3 type composite piezoelectric ceramic of this invention is a piezoelectric ceramic made by sintering in an oxygen-rich atmosphere using PZT-5A powder and nano carbon black as raw materials, with nano carbon black (particle size <100nm) as a sacrificial template and precise control of the amount of nano carbon black. It has pores, which are uniform micropores concentrated in 1μm–5μm. This achieves the purpose of reducing the mechanical quality factor (QM) of the material and improving bandwidth performance while maintaining porosity and structural uniformity.

[0040] Optionally, refer to Figure 2 The ultrasonic sensor in this utility model also includes a backing layer 4, which is stacked on the piezoelectric ceramic 3 in the opposite direction of ultrasonic wave transmission and is concentric with the piezoelectric ceramic 3. The backing layer 4 is fixedly connected in the receiving space 11.

[0041] In this embodiment, the backing layer 4 and the piezoelectric ceramic 3 are concentrically abutted and fixed in the receiving space 11. The backing layer 4 absorbs the acoustic energy radiated from the piezoelectric ceramic 3, converting the residual vibration energy into heat energy dissipation, thereby improving the time resolution of flow detection. The fixed connection structure between the backing layer 4 and the inner wall of the receiving space 11 enhances the overall mechanical stability. At the same time, it also serves as a heat conduction path to conduct the working heat generated by the piezoelectric ceramic 3 to the outside of the first matching layer 1, avoiding signal drift caused by continuous temperature rise in the receiving space 11 and ensuring detection accuracy.

[0042] Optionally, refer to Figure 1 The ultrasonic sensor in this utility model also includes a connecting wire group 5, one end of which extends into the receiving space 11 and is electrically connected to the piezoelectric ceramic 3, and the other end of which is electrically connected to the external electronic processing system.

[0043] In this embodiment, one end of the connecting wire group 5 extends into the accommodating space 11 and is connected to the piezoelectric ceramic electrode 3, while the other end is connected to the external electronic processing system to realize signal transmission between the ultrasonic sensor and the external electronic processing system.

[0044] Optionally, refer to Figure 2 , Figure 3 and Figure 4 The connecting wire assembly 5 in this utility model includes a shielding section 51 and a conductor section 52; one end of the shielding section 51 is electrically connected to an external electronic processing system, and the other end extends into the accommodating space 11; the conductor section 52 includes a first conductor 521 and a second conductor 522, which are electrically connected to corresponding sides of the piezoelectric ceramic 3, and both the first conductor 521 and the second conductor 522 are electrically connected to the shielding section 51.

[0045] In this embodiment, the shielding section 51 wraps around the conductor section 52 extending to the external electronic processing system, reducing external electromagnetic interference and protecting the conductor; the first conductor 521 and the second conductor 522 are respectively connected to the electrodes of the piezoelectric ceramic 3 and then converge to the shielding section 51 to form a signal loop.

[0046] Optionally, the conductor segment 52 in this utility model is a bare wire.

[0047] In this embodiment, the conductor segment 52 adopts a bare wire structure without insulation coating, which reduces the capacitance / inductance loss of the conductor, improves signal integrity, and enhances detection accuracy.

[0048] Optionally, in this invention, there is a gap between the backing layer 4 and the inner wall of the accommodating space 11, and both the first and second wires pass through the gap and are electrically connected to the piezoelectric ceramic.

[0049] In this embodiment, the gap reserved between the backing layer 4 and the inner wall of the receiving space 11 serves as a dedicated channel for the wire segment 52, eliminating the stress exerted on the piezoelectric ceramic 3 by the wire swing and preventing the generation of ceramic microcracks; the gap can be filled with silicone sealant to form a stress buffer layer, which absorbs deformation energy when the sensor is impacted by fluid pressure, reducing the amplitude of wire swing; at the same time, it ensures that the first wire 521 and the second wire 522 are symmetrically distributed on both sides of the piezoelectric ceramic 3, reducing possible delays.

[0050] Optionally, the first matching layer 1 in this invention includes a shell portion 12 and a support portion 13;

[0051] The shell portion 12 and the support portion 13 enclose and form an accommodating space 11, and the second matching layer 2 abuts against the support portion 13.

[0052] In this embodiment, the first matching layer 1 includes a shell portion 12 and a support portion 13. The shell portion 12 serves as the housing of the ultrasonic sensor to accommodate and protect the components in the accommodating space. The support portion 13 serves as the mounting reference surface of the second matching layer 2 and as the matching layer material that cooperates with the second matching layer 2, forming a structure with gradually changing acoustic impedance.

[0053] Optionally, the thickness of the support portion 13 in this invention is greater than the thickness of the second matching layer 2. Furthermore, the thickness of the support portion 13 and the thickness of the second matching layer 2 are both designed based on the acoustic impedance formula.

[0054] In this embodiment, the thickness of the support portion 13 is greater than the thickness of the second matching layer 2. At the same time, the thicknesses of the support portion 13 and the second matching layer 2 are designed according to the acoustic impedance formula. In specific use, the process of making the acoustic impedance drop from the piezoelectric ceramic 3 (about 30 MRayl) to the liquid (about 1.5 MRayl) is completed in two stages: the second matching layer 2 achieves the first reduction of acoustic impedance (specifically, it drops to about 8-10 MRayl), and the support portion 13 further reduces the acoustic impedance to about 4-5 MRayl, thereby reducing the reflection coefficient of sound waves at the interlayer interface.

[0055] Optionally, the outer side of the first matching layer 1 in this invention is provided with an anti-corrosion coating.

[0056] In this embodiment, the outer surface of the first matching layer 1 is coated with an anti-corrosion coating, such as polyvinylidene fluoride (PVDF), to resist corrosion that may be caused by the test liquid during use.

[0057] Furthermore, the thickness of the anti-corrosion coating should be controlled between 5μm and 20μm to avoid excessive thickness affecting the acoustic wave transmission phase; the coating also acts as a sacrificial layer for mechanical wear, extending the service life of the sensor in fluids containing solid particles.

[0058] Optionally, the second matching layer 2 in this invention has a bonding layer between it and the sidewall of the accommodating space 11.

[0059] In this embodiment, a bonding layer is provided between the second matching layer and the side wall of the accommodating space. Specifically, it can be an epoxy resin-based bonding layer, which fills the gap between the first matching layer 1 and the second matching layer 2, eliminates the acoustic impedance abrupt change point caused by air gap, and forms a mechanical interlocking structure after the bonding layer is cured, thereby enhancing the structural strength of the ultrasonic sensor.

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An ultrasonic sensor for liquid flow detection, characterized in that, include: The first matching layer (1), the second matching layer (2), and the piezoelectric ceramic (3) are included; among them, The first matching layer (1) has a accommodating space (11); The piezoelectric ceramic (3) and the second matching layer (2) are concentrically stacked in the accommodating space (11) along the ultrasonic transmission direction, and the second matching layer (2) abuts against the inner wall of the accommodating space (11), and the piezoelectric ceramic (3) abuts against the second matching layer (2). Furthermore, the piezoelectric ceramic (3) is a 0-3 type composite piezoelectric ceramic.

2. The ultrasonic sensor of claim 1, wherein, The ultrasonic sensor also includes a backing layer (4), which is stacked on the piezoelectric ceramic (3) in the opposite direction of ultrasonic transmission and is concentric with the piezoelectric ceramic (3). The backing layer (4) is fixedly connected in the receiving space (11).

3. The ultrasonic sensor of claim 2, wherein, The ultrasonic sensor also includes a connecting wire assembly (5) with one end extending into the receiving space (11) and electrically connected to the piezoelectric ceramic (3), and the other end electrically connected to an external electronic processing system.

4. The ultrasonic sensor of claim 3, wherein, The connecting wire assembly (5) includes a shielding section (51) and a conductor section (52); One end of the shielding section (51) is electrically connected to an external electronic processing system, and the other end extends into the accommodating space (11); The conductor segment (52) includes a first conductor (521) and a second conductor (522). The first conductor (521) and the second conductor (522) are electrically connected to corresponding sides of the piezoelectric ceramic (3), and both the first conductor (521) and the second conductor (522) are electrically connected to the shielding segment (51).

5. The ultrasonic sensor of claim 4, wherein, The conductor segment (52) is a bare wire.

6. The ultrasonic sensor of claim 4, wherein, There is a gap between the backing layer (4) and the inner wall of the accommodating space (11), and the first conductor (521) and the second conductor (522) both pass through the gap and are electrically connected to the piezoelectric ceramic (3).

7. The ultrasonic sensor of claim 1, wherein, The first matching layer (1) includes a shell portion (12) and a support portion (13); The shell portion (12) and the supporting portion (13) enclose the receiving space (11), and the second matching layer (2) abuts against the supporting portion (13).

8. The ultrasonic sensor according to claim 7, characterized in that, The thickness of the bearing portion (13) is greater than the thickness of the second matching layer (2).

9. The ultrasonic sensor according to claim 1, characterized in that, The first matching layer (1) has an anti-corrosion coating on its outer side.

10. The ultrasonic sensor of claim 1, wherein, The second matching layer (2) has a bonding layer between it and the sidewall of the accommodating space (11).

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