A converter, a manufacturing process and a flow meter

Abstract

The present invention relates to the technical field of fluid flow measurement, in particular a transducer, a manufacturing method, and a flow measuring device. It comprises a body and an acoustic communication rod, wherein the body and the acoustic communication rod are rigidly connected, and the radiating surface of the body rests against one end of the acoustic communication rod to enable signal transmission. The special feature is that the acoustic matching layer of the body is made of a composite material containing silver and epoxy resin. The composite material contains, by mass ratio, 2 to 4 parts silver powder and 6 to 8 parts AB adhesive. This transducer exhibits good electrical performance and excellent acoustic matching, and the measurement results of the flow measuring device with this transducer show lower deviation.

Description

Technical field

[0001] The present invention relates to the technical field of fluid flow measurement, more precisely to a transducer, a manufacturing process and a flow meter. Background technology

[0002] An ultrasonic flow meter is a device that uses the time-difference method to measure fluid flow in a pipe. It determines the fluid's flow velocity by measuring the time an ultrasonic pulse takes to travel back and forth between two ultrasonic transducers when flowing with or against the flow, and calculates the fluid flow rate from this measurement. An ultrasonic flow meter primarily comprises a host and transducers, with the transducer leads connected to the host. The transducer contains a body and a transducer rod, which are rigidly connected. The body's radiating surface abuts one end of the transducer rod to transmit the signal.

[0003] Currently, the acoustic matching layer in conventional transducers consists of low-viscosity plastic, PEEK, or epoxy resin. However, due to the inherent properties of these materials, the resulting acoustic matching layer exhibits poor electrical properties and insufficient acoustic matching, leading to significant measurement deviations in the flow meter readings. Subject of the invention

[0004] The technical problem to be solved by the present invention is to provide a transducer, a manufacturing method and a flow measuring device, wherein the transducer has good electrical properties and good acoustic matching and the measurement results are associated with lower deviations.

[0005] To solve the problems mentioned above, the following scheme is applied: The transducer of the present invention comprises a body and a sound communication rod, wherein the body and the sound communication rod are rigidly connected to one another, and the radiating surface of the body abuts one end of the sound communication rod to effect signal transmission. It is characterized in that the acoustic matching layer of the body is made of a composite material consisting of silver and epoxy resin. The composite material contains, according to the mass ratio, 2 to 4 parts silver powder and 6 to 8 parts AB adhesive.

[0006] The device comprises a housing and a wire. The housing contains a support cylinder in which a cylindrical backing plate is arranged coaxially. The inner end of the backing plate is a smooth plane, while the outer end has an irregular, uneven surface. The inner end of the backing plate is covered with a piezoelectric ceramic sheet, which serves as the acoustic transmitting and receiving element. The acoustic matching layer is located between the piezoelectric ceramic sheet and the base of the support cylinder's interior. A retaining device is situated between the backing plate and the interior of the support cylinder, securing the backing plate, the piezoelectric ceramic sheet, and the acoustic matching layer within the support cylinder. The backing plate is connected to one end of the wire, and the other end of the wire extends outward through the opening of the support cylinder.The outer end face of the base of the support cylinder is the aforementioned radiation surface.

[0007] The limiting device comprises a limiting sleeve and a press nut. The limiting sleeve is fitted over the piezoelectric ceramic blade and the backing plate, and the outer circumferential surface of the limiting sleeve abuts the inside of the support cylinder. An internal thread is provided on the inner circumferential surface of the opening of the support cylinder. The press nut is located in the opening of the support cylinder and is connected to it via a thread. A compression spring is located between the inner side of the press nut and the outer end of the backing plate.

[0008] A connecting pin is arranged concentrically on the outer end of the backing plate, projecting outwards. At the outer end of the connecting pin, a threaded bore is provided along the radial direction of the support cylinder, in which a bolt is located. One end of the wire is positioned between the bolt and the connecting pin. The crimp nut has a through-hole to facilitate the insertion of the wire, and the other end of the wire protrudes through the recess and opening of the support cylinder.

[0009] The support cylinder on the outside around the press nut is filled with a block of adhesive, and the wire passes through the block of adhesive.

[0010] The sound communication rod comprises a long tube, the end of which is closed near the body. The long tube is filled with a transmission element made of cylindrical wires or thin sheets. One end of the transmission element abuts the inner surface of the closed end of the long tube, and a connecting sheet is fixed to the other end of the transmission element, extending outside the opening of the long tube. A protective cap is located between the outer surface of the connecting sheet and the open end of the long tube. A connecting sleeve is fitted to the closed end of the long tube, with its inner end extending over the outer surface of the long tube and being firmly connected to it.A ventilation hole is provided between the inner side wall of the connecting sleeve and the outer side wall of the long tube, arranged in the axial direction of the sound communication rod, and the bottom end of the support cylinder projects from the outer end of the connecting sleeve into the connecting sleeve.

[0011] The manufacturing process of the aforementioned converter is characterized by the fact that it comprises the following steps: First step: create the body and the sound communication rod, respectively. Manufacture the body: produce each of the support cylinder, the piezoelectric ceramic sheet, the backing plate, the compression spring, the limiting bushing, the press nut, the wire and the bolt. The connection process between the connecting pin and the wire is as follows: One end of the wire is wrapped around the bolt, then the bolt is inserted into the threaded hole so that the wire is clamped to the connecting pin;

[0012] The assembly process is as follows: A. To prepare the acoustic matching layer on the bottom of the support cylinder's interior: First, mix 2-4 parts silver powder according to mass ratio with 6-8 parts AB adhesive and stir well to obtain a sticky mixture; then, apply the mixture evenly to the bottom of the support cylinder's interior, with a thickness of 1 / 4 the wavelength of the ultrasound; after the mixture applied to the support cylinder has dried, the acoustic matching layer is obtained. B. After completion of the production of the acoustic matching layer, the limiting sleeve, the piezoelectric ceramic sheet, the backing, the compression spring and the press nut are first inserted into the support cylinder, and the outer end of the wire is led out through the recess hole from the support cylinder; then the press nut is tightened so that the compression spring is compressed to fix the backing in the support cylinder. C. High-temperature sealant is poured into the support cylinder outside the press nut, and after the high-temperature sealant cools, the adhesive block forms, from which the aforementioned body is obtained.

[0013] Acoustic communication rod: manufacture each of the long tube, the transmission section, the connecting plate, the protective cover, and the connecting socket. The assembly process is as follows: The connection process between the transmission section, the connecting sheet, the protective hood and the long pipe is as follows: A. By welding, the ends of all cylindrical wires or thin sheets in the transmission section are successively and evenly applied to the connecting sheet. B. The transmission section is inserted into the long pipe after low-temperature treatment. C. The protective hood is firmly connected to the open section of the long tube, the transmission section expands as the temperature rises, the transmission section connects firmly to the interior of the long tube, and the protective hood rests against the connecting sheet.

[0014] The connection process between the connecting sleeve and the long tube is as follows: The connecting sleeve is placed over the closed outer end of the long tube, and the connecting sleeve is firmly joined to the long tube by welding; during the welding process, it is ensured that a gap exists between one side of the connecting sleeve and the long tube to form the ventilation holes. Second step: assembling the body and the sound communication rod

[0015] First, coupling agent is applied to the outer surface of the base of the support cylinder and to the outer surface of the closed end of the long tube; then, the base end of the support cylinder is inserted into the connecting sleeve, the support cylinder and the connecting sleeve are firmly connected by threads or a clamp, the base end of the support cylinder rests against the closed end of the long tube, and the coupling agent flows under pressure into the gap, thereby forcing the air between the support cylinder, the long tube, and the connecting sleeve into the gap, so that the radiating surface of the body rests firmly against the sound communication rod and stable signal transmission is ensured.

[0016] A flow meter comprising a host (3) and at least two transducer groups, each transducer group having two transducers, and the wires (1013) of the transducers being connected to the host (3), characterized in that the transducer is a transducer according to the above scheme.

[0017] The application of the above-mentioned scheme offers the following advantages: 1. Since the acoustic matching layer of the transducer of the present invention is made of a mixture of silver and epoxy resin, this mixture exhibits good electrical properties and excellent acoustic matching, so that the measurement results of the flow meter with this transducer are accurate. 2. Since the back surface of the transducer of the present invention has an irregular plane, the use of an irregular back surface can inhibit the propagation of ultrasound within the back surface, perform a diffuse reflection function, and ultimately achieve an acoustic damping effect to ensure a low signal-to-noise ratio. The surface of conventional back surfaces is smooth, resulting in a low signal-to-noise ratio. Prior art also includes methods in which back surfaces are manufactured from novel materials created by combining several materials. By adding acoustic damping materials to these novel materials, an acoustic damping effect is achieved, resulting in back surfaces with a high signal-to-noise ratio. However, the processing technique for combining several materials is complex.The backing of the present invention is machined directly from conventional graphite-bronze material, without the need to first produce and then machine a composite material, which significantly simplifies the processing process. 3. Because ventilation holes are provided between the connecting bushing and the long tube of the transducer of the present invention, the coupling agent applied when connecting the support cylinder and the long tube can flow into these ventilation holes, thereby expelling the air between the bottom of the support cylinder and the closed end of the long tube. This allows the support cylinder and the closed end of the long tube to fit tightly together, ensuring excellent intensity of the acoustic signal received by the transducer, reducing measurement errors, and improving measurement stability. Description of the drawings Fig.Figure 1 shows a schematic representation of the structure of the converter of the present invention; Fig. 2 shows a sectional view of the body in the converter of the present invention; Fig. Figure 3 shows a schematic representation of the structure of the backing plate in the converter of the present invention; Fig. Figure 4 shows a sectional view of the sound communication rod in the transducer of the present invention (with a transmission section made of thin sheets); Fig. Figure 5 shows an end view of the transmission section formed from thin sheets in the converter of the present invention; Fig. Figure 6 shows a sectional view of the connection between the body and the sound communication rod in the transducer of the present invention; Fig. Figure 7 shows a schematic representation of the structure of the measuring device of the present invention; Fig.Figure 8 shows a comparison diagram of the signal-to-noise ratio between the converter of the present invention and a converter with a flat back surface of the backing material; Fig. Figure 9 shows a comparison diagram of the intensity of the acoustic signal received by the transducer of the present invention and of the acoustic signal received by a transducer without ventilation holes; Fig. Figure 10 shows a comparison diagram of the acoustic signal between the transducer of the present invention and a conventional transducer. Examples of implementation

[0018] The present invention will now be described with reference to the Fig. 1-10 and the examples of implementation are described in more detail. Example 1

[0019] As in Fig.As shown in Figure 1, the transducer of the present invention comprises a body 1 and an acoustic communication rod 2. The body 1 is a piezoelectric transducer. The body 1 and the acoustic communication rod 2 are rigidly connected to each other, and the radiating surface of the body 1 abuts one end of the acoustic communication rod 2 to effect signal transmission. The acoustic matching layer 1010 of the body 1 consists of a mixture of silver and epoxy resin. The mixture contains, in a mass ratio of 3 parts silver powder and 7 parts AB adhesive. This mixture exhibits good electrical properties and excellent acoustic matching, ensuring accurate measurement results from the flow meter using this transducer. The acoustic communication rod 2 isolates the body 1 from the medium, thus protecting the transducer from the effects of the medium's temperature and pressure.

[0020] As in Fig.2 and Fig. As shown in Figure 3, the body 1 comprises a housing and a wire 1013. The housing contains a support cylinder 104 in which a cylindrical backing plate 108 is arranged concentrically. The inner end face of the backing plate 108 is a smooth plane, and the outer end face of the backing plate 108 has an irregular plane. The irregular outer end face can inhibit the ultrasounds at the rear of the backing plate 108, suppress the propagation of ultrasounds within the backing plate 108, cause diffuse reflection, and ultimately achieve an acoustic damping effect. This reduces the oscillations of the acoustic signal, decreases the after-waves, and improves the sensitivity and the narrow pulse shape of the original signal.

[0021] The inner end face of the backing 108 is covered with a piezoelectric ceramic sheet 1011, which serves as an acoustic transmitting and receiving element. There are two types of ceramic sheets: those with and those without crimped edges. To achieve a better piezoelectric effect, the present invention uses a piezoelectric ceramic sheet 1011 made of non-crimped piezoelectric ceramic.

[0022] The acoustic adaptation layer 1010 is located between the piezoelectric ceramic sheet 1011 and the bottom of the interior of the support cylinder 104. A retaining device is located between the backing 108 and the interior of the support cylinder 104. This device secures the backing 108, the piezoelectric ceramic sheet 1011, and the acoustic adaptation layer 1010 within the support cylinder 104. The retaining device comprises a retaining bushing 109 and a press nut 105. The retaining bushing 109 is fitted over the piezoelectric ceramic sheet 1011 and the backing 108, and its outer circumferential surface abuts the inside of the support cylinder 104. An internal thread is machined onto the inner circumferential surface of the opening of the support cylinder 104. The press nut 105 is located in the opening of the support cylinder 104 and is connected to it via a thread.A compression spring 106 is located between the inner side of the press nut 105 and the outer end of the backing pad 108. The limiting bushing 109 serves to radially limit the backing pad 108, ensuring that the backing pad 108 is centered within the support cylinder 104. The limiting bushing 109 is used as a structural component to fix the backing pad 108; it does not transmit any effective acoustic signals and must exhibit high and low temperature resistance. Therefore, Teflon or PEEK is chosen for it, and in this embodiment, the limiting bushing 109 is made of Teflon. When the press nut 105 is tightened downwards, the compression spring 106 is compressed, and its force ensures a tight connection between the backing pad 108 and the piezoelectric ceramic sheet 1011, as well as between the piezoelectric ceramic sheet 1011 and the acoustic matching layer 1010.In the support cylinder 104 above the press nut 105, an adhesive block 103 is arranged, which fulfills a secondary limiting effect.

[0023] A coaxially projecting connecting pin 107 is arranged on the outer end of the backing plate 108. A threaded bore 1012, extending radially towards the support cylinder 104, is located on the outer end of the connecting pin 107. A bolt 1016 is seated in this bore. One end of the wire 1013 is located between the bolt 1016 and the connecting pin 107. The press nut 105 has a recess 1014 that facilitates the passage of the wire 1013, and the other end of the wire 1013 extends outwards through the recess 1014 and the opening of the support cylinder 104. To facilitate contact between the wire 1013 and the connecting pin 107, the upper side of the connecting pin 107 is provided with two parallel planes, and the two ends of the threaded bore 1012 are each located on these two planes, as shown in Fig. 3 shown.

[0024] In this embodiment, a protective cylinder 1015 made of Teflon is arranged between the compression spring 106 and the connecting pin 107. The protective cylinder 1015 is fitted over the connecting pin 107, and the outer wall of the protective cylinder 1015 abuts the inner wall of the compression spring 106. The cylindrical protective cylinder 1015 serves to guide the compression spring 106 and prevents deformation of the compression spring 106.

[0025] In this embodiment, a top cover 101 is provided at the opening of the support cylinder 104 to better protect the core components of the body 1. The top cover 101 is firmly connected to the support cylinder 104, and a through-hole 102 is located on the side wall of the top cover 101 to facilitate the passage of the wire 1013.

[0026] As in Fig.As shown in Figure 4, the sound communication rod 2 comprises a long tube 203, the end of which is closed near the body 1. The long tube 203 is filled with a transmission section 204 made of cylindrical wires or thin sheets (see Figure 4). Fig. 5) Tests and trials have shown that the best acoustic transmission performance is achieved when using 316SS cylindrical wires with a radius of 0.5 mm or thin steel strips with dimensions of 1 × 15 mm. In this embodiment, the transmission section 204 consists of steel strips with dimensions of 1 × 15 mm.

[0027] As in Fig.As shown in Figure 4, one end of the transmission section 204 abuts the inner surface of the closed end of the long tube 203, and a connecting plate 206, made of silver, is attached to the other end of the transmission section 204. The connecting plate 206 is located outside the opening of the long tube 203, and a protective sleeve 205 made of 316SS is located between the outer surface of the connecting plate 206 and the open end of the long tube 203. The protective sleeve 205 is threaded and firmly connected to the opening of the long tube 203. A connecting bushing 201 is fitted over the closed end of the long tube 203, with the inner end of the connecting bushing 201 being fitted over the outer surface of the long tube 203 and firmly connected to it.Between the inner side wall of the connecting sleeve 201 and the outer side wall of the long tube 203, there are ventilation holes arranged along the axial direction of the sound communication rod 2, and the bottom end of the support cylinder 104 projects from the outer end of the connecting sleeve 201 into it.

[0028] As in Fig.As shown in Figure 6, the support cylinder 104 and the connecting sleeve 201 are firmly connected via threads or a clamp. For the clamp connection, reference can be made to the structure of Chinese patent application number 2022103031383. In this embodiment, the body 1 and the sound communication rod 2 are connected via threads: An external thread is machined on the outer end face of the bottom end of the support cylinder 104, and an internal thread is machined on the inner surface of the connecting sleeve 201. The bottom end of the support cylinder 104 is screwed into the connecting sleeve 201 until the bottom surface of the support cylinder 104 abuts the closed end of the long tube 203.

[0029] The manufacturing process of the converter in this embodiment comprises the following steps: First step: produce body 1 and sound communication rod 2 respectively.

[0030] Manufacture of body 1: manufacture each of the support cylinder 104, the piezoelectric ceramic sheet 1011, the backing 108, the compression spring 106, the limiting bushing 109, the press nut 105, the wire 1013, the bolt 1016 and the protective cylinder 1015.

[0031] The support cylinder 104 is made of SS316 or titanium alloy. In this embodiment, the support cylinder 104 is made of titanium alloy. The piezoelectric ceramic blade 1011 is made of non-flanged piezoelectric ceramic. The limiting bushing 109 is made of Teflon. The backing plate 108 and the connecting pin 107 are machined in one piece from graphite bronze. A threaded hole 1012 is then machined in the upper end of the connecting pin 107, and finally, a silver plating process is carried out. The advantage of manufacturing the backing plate 108 and connecting pin 107 in one piece is that welding is avoided, thus preventing the problem of the silver plating flaking off due to welding.

[0032] The connection process between connecting pin 107 and wire 1013 is as follows: One end of the wire 1013 is wrapped around the bolt 1016, then the bolt 1016 is inserted into the threaded hole 1012, so that the wire 1013 is clamped to the connecting pin 107.

[0033] The assembly process is as follows: A. Preparation of the acoustic matching layer 1010 on the bottom of the interior of the support cylinder 104: First, 3 parts silver powder are mixed by mass with 7 parts AB adhesive and stirred thoroughly to obtain a sticky mixture. The mixture is then applied evenly to the bottom of the interior of the support cylinder 104, with a thickness equal to 1 / 4 of the wavelength of the ultrasound. After the mixture applied to the support cylinder 104 has dried, the acoustic matching layer 1010 is obtained. The AB adhesive consists of 1 part A adhesive and 3 parts B adhesive by mass. B. After completion of the production of the acoustic matching layer 1010, the limiting bushing 109, the piezoelectric ceramic sheet 1011, the backing 108, the protective cylinder 1015, the compression spring 106, and the press nut 105 are first inserted into the support cylinder 104, and the outer end of the wire 1013 is led outwards through the recess hole 1014 from the support cylinder 104. The press nut 105 is then tightened so that the compression spring 106 is compressed, thereby fixing the backing 108 in the support cylinder 104. C. High-temperature sealant is poured into the support cylinder 104 outside the press nut 105. After the high-temperature sealant cools, the adhesive block 103 forms, from which the body 1 is obtained.

[0034] Sound communication rod 2: produce each of the long tube 203, the transmission section 204, the connecting sheet 206, the protective sleeve 205 and the connecting socket 201.

[0035] Connection process of transmission section 204, connection sheet 206, protective sleeve 205 and long pipe 203: A. Using the AgCu soldering process, the ends of all cylindrical wires or thin sheets in the transmission section 204 are successively and uniformly applied to the connecting sheet 206. B. The transmission section 204 is cooled by cooling with liquid nitrogen and then inserted into the long pipe 203. C. The protective sleeve 205 is threaded and firmly connected to the open section of the long tube 203. After tightening the thread, a weld is made between the protective sleeve 205 and the inclined surface of the long tube 203 to ensure the integrity and tightness of the sound communication rod 2, making it suitable for use under high pressure. The transmission section 204 expands as the temperature rises, thus becoming firmly connected to the interior of the long tube 203, and the protective sleeve 205 abuts the connecting plate 206.

[0036] The steel strip is soldered to the connecting sheet 206 using an AgCu soldering process, and the solder thickness is controlled to be 1 / 4 of the ultrasonic wavelength to ensure superior acoustic matching. This soldering method ensures that the transmission section 204 operates stably and reliably at 800 °C.

[0037] Connection process of connecting sleeve 201 and long tube 203: The connecting sleeve 201 is placed over the outside of the closed end of the long tube 203 and welded firmly to the long tube 203. During the welding process, it is ensured that a gap 202 of 0.5 to 1 mm exists between one side of the connecting sleeve 201 and the long tube 203, thus forming the ventilation holes. Second step: Assemble body 1 and sound communication rod 2.

[0038] First, coupling agent is applied to the outer surface of the base of the support cylinder 104 and to the outer surface of the closed end of the long tube 203. Then, the base of the support cylinder 104 is screwed into the connecting sleeve 201 until it abuts the closed end of the long tube 203. The coupling agent flows under pressure into the gap 202, forcing the air between the support cylinder 104, the long tube 203, and the connecting sleeve 201 into the gap 202. This ensures that the radiating surface of the body 1 is firmly in contact with the acoustic communication rod 2, guaranteeing stable signal transmission.

[0039] Due to the gap 202, the coupling medium flows under pressure into this gap when the body 1 is tightened, compressing the air between the body 1 and the coupling rod. Without this gap, the air between the contact surfaces would prevent the body 1 and the coupling rod from fitting tightly together, ultimately leading to a reduction in the amplitude of the acoustic signal transmission and to measurement anomalies. Furthermore, the gap 202 has the property of isolating acoustic noise from pipelines. After the body 1 is assembled, the gap 202, by virtue of its existence, can act as a decoupling medium when acoustic noise caused by high-frequency ambient vibrations of the pipeline passes through the coupling rod.

[0040] As in Fig.As shown in Figure 7, the flow measuring device of the present invention comprises a host 3 and at least two transducer groups, each transducer group comprising two transducers from this embodiment, and the wires 1013 of the transducers are each connected to the host 3. The connection method between the transducers and the fluid pipeline can be found in Chinese patent application number 2022103031383. Example 2

[0041] In comparison to embodiment 1, the mixture contains, according to the mass ratio, 2 parts silver powder and 8 parts AB adhesive. Example 3

[0042] In comparison to embodiment 1, the mixture contains, according to the mass ratio, 4 parts silver powder and 6 parts AB adhesive. Comparative example 1

[0043] In contrast to embodiment 1, the acoustic adaptation layer 1010 is made of plastic. Comparative example 2

[0044] In contrast to embodiment 1, the acoustic matching layer 1010 consists of PEEK. Comparative example 3

[0045] In contrast to embodiment 1, the acoustic adaptation layer 1010 consists of low viscosity epoxy resin. Comparative example 4

[0046] In comparison to embodiment 1, the mixture contains, according to the mass ratio, 1 part silver powder and 9 parts AB adhesive. Comparative example 5

[0047] In comparison to embodiment 1, the mixture contains, according to the mass ratio, 5 parts silver powder and 5 parts AB adhesive.

[0048] The following table shows the performance parameters of the acoustic matching layers of all embodiments and comparison examples: object Implementation example 1 Example 2 Example 3 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Impedance (Ω) 50 1000 540 13M 10M 5,6M 6,7M 5,5K Acoustic impedance component (Pa*s / m) 3,5×10 6 7,5×10 6 6,3×10 6 8,5×10 6 6,7×10 6 5,5×10 6 6,9×10 6 7,2×10 6

[0049] The table shows that the impedance of the acoustic matching layers 1010 in all embodiments is below 1000 Ω, while the impedance of the acoustic matching layers 1010 in the comparison examples is above 5.5 kΩ. The acoustic impedance component of both all embodiments and the comparison examples meets the requirements. Thus, it is clearly evident that the acoustic matching layer 1010 of the transducer of the present invention has a lower impedance and an appropriate acoustic impedance component, resulting in excellent electrical and acoustic properties for the transducer. This ensures accurate measurement results and good stability of the flow metering device using the transducer of the present invention.

[0050] A signal-to-noise ratio test was performed on the converter of embodiment 1, and the resulting curve is in the upper half of Fig. Figure 8 shows that the backing plate of the converter in embodiment 1 was replaced by a backing plate with a smooth back surface, and another signal-to-noise ratio test was performed, with the resulting curve in the lower half of Fig.Figure 8 shows that a backing plate with an irregular back surface improves the signal-to-noise ratio of the transducer, leading to a stable testing process and accurate test results for the flow meter. While manufacturing backing plates from novel materials created by combining several materials can also ensure a good signal-to-noise ratio, the processing technique for combining multiple materials is more complex and efficient compared to the one-piece manufacturing of the backing plate of the present invention from conventional graphite-bronze material.

[0051] A test for the received signal intensity was performed on the converter of embodiment 1, and the resulting curve is in the upper half of Fig.Figure 9 shows that during the manufacture of the transducer of embodiment 1, the ventilation holes were removed to obtain a transducer without ventilation holes. A test for the received signal intensity was also performed on this transducer, and the resulting curve is shown in the lower half of Figure 9. Fig. Figure 9 shows that the arrangement of ventilation holes allows for a close fit between the support cylinder and the closed end of the long tube, resulting in excellent intensity of the received acoustic signal from the transducer. This reduces measurement errors and improves measurement stability.

[0052] After the actual measurement, as in Fig.As shown in Figure 10, the original acoustic echo signal detected by the transducer of the present invention is significantly improved compared to the conventional transducer, and the output drive signal is also significantly increased. This considerably improves the measurement accuracy of the flow measuring device with the transducer of the present invention.

Claims

[1] A transducer comprising a body (1) and a sound communication rod (2), wherein the body (1) and the sound communication rod (2) are rigidly connected, and the radiating surface of the body (1) is in contact with one end of the sound communication rod (2) to enable signal transmission; characterized by , that the acoustic matching layer (1010) of the body (1) is made of a mixture material containing silver and epoxy resin; the mixture material contains, by mass ratio, 2~4 parts silver powder and 6~8 parts AB adhesive. [2] The converter according to claim 1, characterized by, that the body (1) comprises a housing and a wire (1013), the housing containing a support cylinder (104) in which a cylindrical backing (108) is arranged concentrically, wherein the inner end face of the backing (108) is a smooth plane and the outer end face of the backing (108) has an irregular, uneven surface; the inner end of the backing (108) is covered with a piezoelectric ceramic sheet (1011) which serves as an acoustic transmitting and receiving element, the acoustic matching layer (1010) lies between the piezoelectric ceramic sheet (1011) and the bottom of the interior of the support cylinder (104), and a limiting device is arranged between the backing (108) and the interior of the support cylinder (104) so ​​that the backing (108), the piezoelectric ceramic disc (1011) and the acoustic matching layer (1010) are fixed in the support cylinder (104);The backing (108) is connected to one end of the wire (1013), and the other end of the wire (1013) protrudes through the opening of the support cylinder (104); the outer end face of the bottom of the support cylinder (104) is the said radiating surface. [3] The converter according to claim 2, characterized by , that the limiting device comprises a limiting sleeve (109) and a press nut (105); the limiting sleeve (109) is fitted over the piezoelectric ceramic disc (1011) and the backing (108), and the outer circumferential surface of the limiting sleeve (109) abuts the outside of the support cylinder (104); the inner circumferential surface of the opening of the support cylinder (104) is provided with an internal thread, the press nut (105) is located in the opening of the support cylinder (104) and is connected to it via a thread, and a compression spring (106) is arranged between the inner side of the press nut (105) and the outer end of the backing (108). [4] The converter according to claim 3, characterized by , that on the outer end of the backing (108) a connecting pin (107) projecting outwards is arranged concentrically, a threaded bore (1012) arranged in the radial direction of the support cylinder (104) is provided at the outer end of the connecting pin (107), a bolt (1016) is provided in the threaded bore (1012), one end of the wire (1013) lies between the bolt (1016) and the connecting pin (107), a through-hole (1014) is provided in the press nut (105) for easy passage of the wire (1013), and the other end of the wire (1013) protrudes through the through-hole (1014) and the opening of the support cylinder (104). [5] The converter according to claim 4, characterized by , that the support cylinder (104) is filled with an adhesive block (103) around the outside of the press nut (105), and the wire (1013) passes through the adhesive block (103). [6] The converter according to claim 5, characterized by, that the sound communication rod (2) comprises a long tube (203), wherein the end of the long tube (203) is closed near the body (1), the long tube (203) is filled with a transmission part (204) made of cylindrical wires or thin sheets, one end of the transmission part (204) abuts the inner surface of the closed end of the long tube (203), a connecting sheet (206) is fixed to the other end of the transmission part (204), the connecting sheet (206) lies outside the opening of the long tube (203), and a protective hood (205) is arranged between the outside of the connecting sheet (206) and the open end of the long tube (203);A connecting sleeve (201) is fitted over the closed end of the long tube (203), the inner end of the connecting sleeve (201) is fitted over the outer side of the long tube (203) and firmly connected to it, a ventilation hole arranged in the axial direction of the sound communication rod (2) is provided between the inner side wall of the connecting sleeve (201) and the outer side wall of the long tube (203), and the bottom end of the support cylinder (104) projects from the outer end of the connecting sleeve (201) into the connecting sleeve (201). [7] Method for manufacturing a converter according to claim 6, characterized by that it includes the following steps: First step: produce the body (1) and the sound communication rod (2) respectively. To manufacture the body (1): manufacture the support cylinder (104), the piezoelectric ceramic sheet (1011), the backing (108), the compression spring (106), the limiting bushing (109), the press nut (105), the wire (1013) and the bolt (1016) respectively; The connection process between the connecting pin (107) and the wire (1013) is as follows: One end of the wire (1013) is wrapped around the bolt (1016), then the bolt (1016) is inserted into the threaded hole (1012) so that the wire (1013) is clamped to the connecting pin (107); The assembly process is as follows: A. To prepare the acoustic matching layer (1010) on the bottom of the interior of the support cylinder (104): First, 2-4 parts of silver powder are mixed by mass with 6-8 parts of AB adhesive and stirred well to obtain a sticky mixture; then, the mixture is applied evenly to the bottom of the interior of the support cylinder (104), with the application thickness being 1 / 4 of the wavelength of the ultrasound; after the mixture applied to the support cylinder (104) has dried, the acoustic matching layer (1010) is obtained; B. After completion of the production of the acoustic matching layer (1010), the limiting sleeve (109), the piezoelectric ceramic sheet (1011), the backing (108), the compression spring (106) and the press nut (105) are first inserted into the support cylinder (104), and the outer end of the wire (1013) is guided outwards through the recess hole (1014) from the support cylinder (104); subsequently, the press nut (105) is tightened so that the compression spring (106) is compressed to fix the backing (108) in the support cylinder (104); C. High-temperature sealant is poured into the support cylinder (104) outside the press nut (105), and after the high-temperature sealant has cooled, the adhesive block (103) is formed, from which the body (1) is obtained; Sound communication rod (2): Manufacture each of the long tube (203), the transmission section (204), the connecting plate (206), the protective cover (205) and the connecting socket (201). The assembly process is as follows: The connection process between the transmission section (204), the connecting sheet (206), the protective hood (205) and the long tube (203) is as follows: A. By welding, the ends of all cylindrical wires or thin sheets in the transmission section (204) are successively and uniformly applied to the connecting sheet (206); B. The transmission section (204) is inserted into the long pipe (203) after low-temperature treatment; C. The protective hood (205) is firmly connected to the open section of the long tube (203), the transmission section (204) expands when the temperature rises, the transmission section (204) connects firmly to the interior of the long tube (203), and the protective hood (205) rests against the connecting sheet (206); The connection process between the connecting bushing (201) and the long tube (203) is as follows: The connecting sleeve (201) is placed over the closed outer end of the long tube (203), and the connecting sleeve (201) is firmly welded to the long tube (203); during the welding process, it is ensured that a gap (202) exists between one side of the connecting sleeve (201) and the long tube (203) to form the ventilation holes; Second step: assemble the body (1) and the sound communication rod (2). First, coupling agent is applied to the outer surface of the base of the support cylinder (104) and to the outer surface of the closed end of the long tube (203); then the base end of the support cylinder (104) is inserted into the connecting sleeve (201), the support cylinder (104) and the connecting sleeve (201) are firmly connected by thread or a clamp, the base end of the support cylinder (104) rests against the closed end of the long tube (203), and the coupling agent flows under pressure into the gap (202), thereby forcing the air between the support cylinder (104), the long tube (203) and the connecting sleeve (201) into the gap (202), so that the radiating surface of the body (1) rests firmly against the sound communication rod (2) and stable signal transmission is ensured. [8] A flow meter comprising a host (3) and at least two transducer groups, each transducer group having two transducers, and the wires (1013) of the transducers being connected to the host (3), characterized by that the converter is a converter according to one of claims 1 to 6.

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