CN115022784B - Low-frequency piezoelectric transducer integrating flange joint and nested front and rear cover plates - Google Patents
Low-frequency piezoelectric transducer integrating flange joint and nested front and rear cover plates Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R17/00—Piezoelectric transducers; Electrostrictive transducers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/30—Assessment of water resources
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention discloses a low-frequency piezoelectric transducer integrating a flange joint and nested front and rear cover plates. The embedded type front cover plate is fixedly connected with the flange plate end of the flange joint, the plug end of the flange joint is connected with a communication load, and low-frequency sound wave signal transmission of longitudinal vibration is achieved. According to the invention, through designing the nested front cover plate and the nested rear cover plate, the intrinsic frequency of the transducer is effectively reduced under the condition of not increasing the actual length of the transducer, the size of the embedded piezoelectric ceramic transducer is far smaller than that of a sandwich piezoelectric ceramic transducer working in the same frequency band, the embedded piezoelectric ceramic transducer is conveniently connected with a communication load through a flange joint, and the influence of the load on the intrinsic frequency and impedance characteristics of the transducer is effectively reduced.
Description
Technical Field
The invention belongs to the field of transducers, and particularly relates to a low-frequency piezoelectric transducer integrated with a flange joint and nested front and rear cover plates.
Background
In recent years, the development of acoustic wave technology is extremely rapid, the application is increasingly wide, and since acoustic waves belong to material waves, and both solid and liquid are good carriers of acoustic waves, acoustic waves are the most suitable carrier selection in the fields of underwater communication, marine survey, oil well communication and the like. The transducer is an important component in the acoustic wave communication system, the requirements of different purposes on the transducer are also different, when the transducer is in a transmitting state, the transducer converts electromagnetic oscillation into mechanical vibration, a medium is pushed to vibrate, acoustic wave signals are radiated outwards, and the transmitting transducer is required to have high output power and high energy conversion efficiency; when in the receiving state, the transducer converts the received mechanical vibration into an electrical signal, which is transmitted to a demodulation circuit for signal extraction, requiring a wide operating band and high sensitivity of the receiving transducer.
With the increasing demand for long-distance acoustic communication in various fields, the demands for transducers gradually tend to be low-frequency, small-sized and high-power, and low-frequency transducers have been widely used in the fields of marine surveying and communication, and common low-frequency underwater acoustic transducer forms include a bend-open type, a circular ring type and a laminated type; in the field of oil well communication, the acoustic logging low-frequency transducer which can be put into practical production is not more. In oil well communications, the carrier for acoustic transmission may be a drill string, pipe or fluid in the well, and the communication distance is as long as a few kilometers, the development of a low frequency, high power transmitting transducer as the acoustic source generator is a necessary choice, however the size of the transducer is generally proportional to wavelength, so that a lower operating frequency means a larger transducer size, and also means a larger weight and cost, and difficulty in installation and connection. In order to solve the contradiction between the low frequency and the small size of the transducer, a common method is to design a novel transducer structure and increase the equivalent acoustic wave length under the condition of not increasing the actual physical size of the transducer, wherein typical structures are a bending transducer, a spiral slotting transducer, a slotting circular tube transducer and the like. In addition, when the radiation end of the transducer is directly connected with different loads, the impedance characteristic of the transducer may be changed, so that the impedance matching between the transducer and the signal source is affected, and the energy output efficiency of the transducer driving circuit is reduced.
Disclosure of Invention
The invention aims at providing a low-frequency, high-power, low-cost and small-size sound wave transmitting transducer which is suitable for pipeline communication and can generate a sound wave signal of longitudinal vibration under the excitation of an externally applied voltage signal to propagate along a pipeline with a periodic arrangement rule. And a flange joint structure with optimized design is provided for connecting a transducer and a communication load, so that the influence of the load on the eigenfrequency and impedance characteristics of the transducer is reduced.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention comprises a fastening nut, a prestress screw, an insulating sleeve, a nested rear cover plate, a piezoelectric ceramic crystal stack, a nested front cover plate and a flange joint;
the fastening nut and the nested front cover plate are respectively and fixedly arranged at two ends of the prestress screw, an insulating sleeve is sleeved on the outer circumferential side face of the prestress screw between the fastening nut and the nested front cover plate, a nested rear cover plate and a piezoelectric ceramic crystal stack which are sequentially arranged along the axial direction of the prestress screw are sleeved on the outer circumferential side face of the insulating sleeve, the fastening nut, the nested rear cover plate, the piezoelectric ceramic crystal stack and the nested front cover plate are sequentially and tightly arranged along the axial direction of the prestress screw, the nested front cover plate is fixedly connected with one end of a flange plate of the flange joint, the prestress screw and the flange joint are respectively arranged at two ends of the nested front cover plate, the end of the flange joint is used as a radiation end of the low-frequency piezoelectric transducer, and the plug end of the flange joint is connected with a communication load to realize low-frequency sound wave signal transmission of longitudinal vibration.
The nested back cover plate comprises a cylindrical inner cover plate and a cylindrical outer cover plate, wherein the cylindrical inner cover plate is arranged in the cylindrical outer cover plate, the outer circumferential side surface of the cylindrical inner cover plate and the inner circumferential side surface of the cylindrical outer cover plate are arranged at intervals, through holes are formed in the middle of the cylindrical inner cover plate and the middle of the cylindrical outer cover plate, the cylindrical inner cover plate and the cylindrical outer cover plate are tightly sleeved on the outer circumferential side surface of the insulating sleeve, the fastening nut, the bottom of the cylindrical outer cover plate and the cylindrical inner cover plate are sequentially and tightly arranged along the axial direction of the prestress screw, the top of the cylindrical outer cover plate extends to the cylindrical inner cover plate, and the other end surface of the cylindrical inner cover plate and the piezoelectric ceramic crystal stack are tightly arranged.
The piezoelectric ceramic crystal stack comprises piezoelectric ceramic rings and electrode plates, a plurality of piezoelectric ceramic rings are stacked in sequence, one electrode plate is arranged between every two adjacent piezoelectric ceramic rings, each electrode plate is connected with a lead, the polarization directions of the two adjacent piezoelectric ceramic rings are opposite, the piezoelectric ceramic rings and the electrode plates are sleeved on the outer circumferential side face of the insulating sleeve, and the electrode plates arranged at the two ends are respectively and tightly arranged with the nested back cover plate and the nested front cover plate.
The nested front cover plate consists of a cylinder, a first trapezoid round table, a barrel-shaped connecting piece and a second trapezoid round table, wherein one end face of the cylinder is tightly arranged with the piezoelectric ceramic crystal stack, the other end face of the cylinder is fixedly connected with the upper bottom face of the first trapezoid round table, the lower bottom face of the first trapezoid round table is fixedly connected with the inner bottom face of the barrel-shaped connecting piece, the outer bottom face of the barrel-shaped connecting piece is fixedly connected with the lower bottom face of the second trapezoid round table, and the upper bottom face of the second trapezoid round table is fixedly connected with the flange plate end of the flange joint.
The diameter of the lower bottom surface of the first trapezoid round table is smaller than the diameter of the inner bottom surface of the barrel-shaped connecting piece.
The flange joint comprises a flange plate and a screwed plug, one end face of the flange plate is fixedly connected with one end of the nested front cover plate, one end of the screwed plug is fixedly installed in the middle of the other end face of the flange plate, the other end of the screwed plug is used as a radiation end of the low-frequency piezoelectric transducer and used for being connected with communication loads, and a cavity is formed in the flange plate.
The nested back cover plate is made of a metal material with higher density, and the nested front cover plate is made of a metal material with lower density.
The flange joint has two main functions:
1) The device is used for effectively connecting the fixed transducer and a communication load to realize the transmission of sound wave signals;
2) The flange with the cavity structure forms a vibration node (i.e. where vibration is zero) at the bottom plug, thereby reducing the disturbance of the connected load to the natural frequency and impedance characteristics of the transducer.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, the front cover plate structure and the rear cover plate structure of the transducer are designed, and the nested front cover plate and the nested rear cover plate are adopted, so that the intrinsic frequency of the transducer is effectively reduced under the condition that the actual length of the transducer is not increased, and the transducer is driven by a low-frequency voltage signal to vibrate longitudinally and radiate sound wave signals outwards. Compared with a sandwich type piezoelectric transducer working in the same frequency band, the size and the volume of the sandwich type piezoelectric transducer are greatly reduced, the overall height of the transducer is about 1m, the maximum radius is 127mm, the low-frequency longitudinal vibration acoustic wave signal emission in the frequency range of 1KHz can be realized, and the contradiction between the small size and the low frequency of the transducer is overcome. And the intrinsic frequency of the transducer can be changed by adjusting the height of the cylindrical inner cover plate in the rear cover plate of the transducer so as to meet the requirements of working frequencies of different scenes, and the method is strong in robustness and wide in application range. In addition, the transmitting transducer can be directly connected with a communication load through a flange joint with a cavity structure, is convenient to install, and effectively reduces interference of the connected load on the intrinsic frequency and impedance characteristics of the transducer. The transmitting transducer has the advantages of simple integral structure, convenient manufacture, low cost and wide application prospect.
Drawings
Fig. 1 is a schematic diagram of a low-frequency piezoelectric transducer with integrated flange joints and nested front and rear cover plates according to the present invention.
Fig. 2 is a schematic perspective view of a flange joint.
Fig. 3 is a schematic structural diagram of a conventional sandwich-type longitudinal vibration piezoelectric transducer.
Fig. 4 is a graph of the vibrational modes of the transducer at eigenfrequencies 690 Hz.
Fig. 5 is a graph of the transducer eigenfrequency followed by a change in the height of the cylindrical inner cover plate in the cover plate.
FIG. 6 is a graph of the eigenfrequency of a transducer as a function of length of a connecting metal tube.
FIG. 7 is a graph of the vibrational mode of the transducer at an eigenfrequency of 689.5Hz when the transducer is coupled to a flange joint and a 5m pipe.
FIG. 8 is an admittance spectrum of a transducer when the transducer is connected to a flange joint and a 5m pipe.
FIG. 9 is a graph of the Z-direction acceleration spectrum of the radiating surface of the nested front cover plate of the transducer and the bottom of the water injection pipe when the transducer is connected with a flange joint and a 5m pipeline.
In the figure: 1. a fastening nut; 2. a pre-stressing screw; 3. an insulating sleeve; 4. a cylindrical inner cover plate; 5. a drum-shaped outer cover plate; 6. a piezoelectric ceramic crystal stack; 7. a nested front cover plate; 8. a threaded hole; 9. a disc; 10. a barrel-shaped base; 11. and (5) plugging.
Detailed Description
The invention is described in further detail below with reference to the drawings and specific examples, but embodiments of the invention are not limited thereto.
As shown in fig. 1, the invention comprises a fastening nut 1, a prestress screw 2, an insulating sleeve 3, a nested back cover plate, a piezoelectric ceramic crystal stack 6, a nested front cover plate 7 and a flange joint;
the fastening nut 1 and the nested front cover plate 7 are respectively and fixedly arranged at two ends of the prestress screw 2, an insulating sleeve 3 is sleeved on the outer circumferential side surface of the prestress screw 2 between the fastening nut 1 and the nested front cover plate 7, a nested rear cover plate and a piezoelectric ceramic crystal stack 6 which are sequentially arranged along the axial direction of the prestress screw 2 are sleeved on the outer circumferential side surface of the insulating sleeve 3, the fastening nut 1, the nested rear cover plate, the piezoelectric ceramic crystal stack 6 and the nested front cover plate 7 are sequentially and tightly arranged along the axial direction of the prestress screw 2, the nested front cover plate 7 is fixedly connected with one end of a flange plate of a flange joint, the prestress screw 2 and the flange joint are respectively arranged at two ends of the nested front cover plate 7, the end of the flange joint is used as a radiation end of a low-frequency piezoelectric transducer, and the plug end of the flange joint is connected with a communication load to realize low-frequency sound wave signal transmission of longitudinal vibration.
The nested back cover plate comprises a cylindrical inner cover plate 4 and a cylindrical outer cover plate 5, wherein the cylindrical inner cover plate 4 is arranged in the cylindrical outer cover plate 5, the outer circumferential side surface of the cylindrical inner cover plate 4 and the inner circumferential side surface of the cylindrical outer cover plate 5 are arranged at intervals, through holes are formed in the middle of the cylindrical inner cover plate 4 and the cylindrical outer cover plate 5, the cylindrical inner cover plate 4 and the cylindrical outer cover plate 5 are tightly sleeved on the outer circumferential side surface of the insulating sleeve 3, the fastening nut 1, the bottom of the cylindrical outer cover plate 5 and the cylindrical inner cover plate 4 are sequentially and tightly arranged along the axial direction of the prestress screw 2, the top of the cylindrical outer cover plate 5 extends to the cylindrical inner cover plate 4, in a specific implementation, the cylindrical inner cover plate 4 is not necessarily completely arranged in the cylindrical outer cover plate 5, and the axial length of the cylindrical outer cover plate 5 depends on the eigenfrequency of the transducer. The other end face of the cylindrical inner cover plate 4 is closely arranged with the piezoelectric ceramic crystal stack 6.
The piezoelectric ceramic crystal stack 6 comprises piezoelectric ceramic circular rings and electrode plates, a plurality of piezoelectric ceramic circular rings are stacked in sequence, one electrode plate is arranged between every two adjacent piezoelectric ceramic circular rings, each electrode plate is connected with a lead, the polarization directions of the two adjacent piezoelectric ceramic circular rings are opposite, the positive electrode and the negative electrode of each piezoelectric ceramic circular ring are respectively led out through the corresponding electrode plates and then are connected with the lead, the piezoelectric ceramic circular rings and the electrode plates are respectively sleeved on the outer circumferential side face of the insulating sleeve 3, and the electrode plates arranged at the two ends are respectively and tightly arranged with one end face of the cylindrical inner cover plate 4 of the nested rear cover plate and one end face of the cylinder of the nested front cover plate 7.
The nested front cover plate 7 comprises a cylinder, a first trapezoid round table, a barrel-shaped connecting piece and a second trapezoid round table, in the concrete implementation, the nested front cover plate 7 is of an integrated structure formed by the four parts, one end face of the cylinder and an electrode plate at one end of the piezoelectric ceramic crystal stack 6 are closely arranged, the other end face of the cylinder is fixedly connected with the upper bottom face of the first trapezoid round table, the lower bottom face of the first trapezoid round table is fixedly connected with the inner bottom face of the barrel-shaped connecting piece, the outer bottom face of the barrel-shaped connecting piece is fixedly connected with the lower bottom face of the second trapezoid round table, and the diameter of the lower bottom face of the first trapezoid round table is smaller than that of the inner bottom face of the barrel-shaped connecting piece. The top of the barrel-shaped connecting piece extends to the first trapezoid round platform, so that part of the first trapezoid round platform is arranged in the barrel-shaped connecting piece, the outer side face of the first trapezoid round platform and the inner circumferential side face of the barrel-shaped connecting piece are arranged at intervals, and the upper bottom face of the second trapezoid round platform is fixedly connected with the flange plate end of the flange joint.
As shown in fig. 2, the flange joint comprises a flange plate and a plug 11, one end face of the flange plate is fixedly connected with one end of the nested front cover plate 7, one end of the plug 11 is fixedly installed in the middle of the other end face of the flange plate, the other end of the plug 11 is used as a radiation end of the low-frequency piezoelectric transducer and used for connecting communication loads, and a cavity is formed in the flange plate. The cavity is not filled with any medium, i.e. air.
In specific implementation, the flange plate comprises a disc 9 and a barrel-shaped base 10, the middle part of the outer bottom surface of the barrel-shaped base 10 is fixedly connected with one end of a plug 11, the bottom of the barrel-shaped base 10 is fixedly connected with one end surface of the disc 9, a closed cavity is formed between the barrel-shaped base 10 and the disc 9, and the other end surface of the disc 9 is fixedly connected with one end of a nested front cover plate 7. Wherein, a plurality of threaded holes 8 are correspondingly arranged in the end surfaces of the disc 9 and the nested front cover plate 7, and the disc 9 and the nested front cover plate 7 are connected together by bolts respectively arranged in the threaded holes 8 of the end surfaces of the disc 9 and the nested front cover plate 7. In addition, the positions of the disc 9 and the barrel-shaped base 10 can be interchanged, namely, the middle part of one end face of the disc 9 is fixedly connected with one end of the plug 11, and the outer bottom face of the barrel-shaped base 10 is fixedly connected with one end of the nested front cover plate 7.
Specifically, a plurality of through holes are provided at equal intervals on the edge of the end face of the disc 9, correspondingly, the same number of screw holes with equal intervals are provided in the top end face of the barrel-shaped base 10, and a plurality of bolts are used to pass through the through holes and the screw holes to connect the disc 9 with the barrel-shaped base 10; the plug 11 is integrally formed with the barrel-shaped base 10, and threads are formed on the plug 11 for connecting communication loads.
The nested back cover plate is made of a metal material with higher density, and the nested front cover plate 7 is made of a metal material with lower density. Wherein the cylindrical inner cover plate 4 is of the same or different material as the cylindrical outer cover plate 5. In the concrete implementation, the cylindrical inner cover plate 4 is made of lead, the barrel-shaped outer cover plate 5 is made of copper, and all parts of the nested front cover plate are made of aluminum alloy. The prestress screw 2 and the fastening nut 1 are made of steel. The material of the disc 9 is aluminum alloy, and the materials of the barrel-shaped base 10 and the plug 11 are steel. The piezoelectric ceramic ring is made of PZT-8. The electrode plate is made of copper.
The transducer designed by the invention is improved on the basis of the structure of a traditional sandwich type longitudinal vibration piezoelectric transducer, as shown in fig. 3, the traditional sandwich type longitudinal vibration piezoelectric transducer mainly comprises three parts: when the transducer is excited by an external electric field to generate longitudinal vibration, a surface with zero displacement and vibration speed is necessarily present at a certain position inside the transducer, and the surface is called a joint surface. The front and rear portions of the joint have respective frequency equations, which are for the portion containing the front cover plate:
wherein F is the expansion coefficient, defined as f=r 2 /(r 1 -r 2 ) Wherein r is 1 And r 2 Respectively a front cover plate radiation surface and a piezoelectric ceramic crystal stacked connectionRadius of the contact surface; ρ p And ρ 1 The densities of the piezoelectric ceramic crystal stack and the front cover plate material are respectively; c p And c 1 Sound velocity in the piezoelectric ceramic and the front cover plate material respectively; k (k) p And k is equal to 1 Wave numbers in the piezoelectric ceramic crystal stack and the front cover plate material respectively; s is S p And S is equal to 1 The cross-sectional areas of the piezoelectric ceramics and the radiation end of the front cover plate are respectively; l (L) p1 And/l 1 The length of the front piezoelectric ceramic crystal stack and the length of the front cover plate are respectively the length of the front section surface. For the section containing the back cover plate, the frequency equation is:
wherein l p2 And/l 2 The length of the piezoelectric ceramic crystal stack after the section surface and the length of the rear cover plate are respectively; ρ 2 Is the density of the material of the back cover plate; c 2 Is the speed of sound in the back cover material; k (k) 2 Wavenumbers in the front cover material; s is S 2 Is the cross-sectional area of the back cover plate. In general, the front cover plate of the transducer is connected with a load, the rear cover plate is in an empty state, and in order to realize efficient energy conversion, energy is radiated from the front cover plate as much as possible to act on the load, so that the vibration ratio of the front radiation surface and the rear radiation surface of the transducer is improved as much as possible in the design process, and the vibration ratio is defined as:
wherein z is 1 ＝ρ 1 c 1 S 1 ，z 2 ＝ρ 2 c 2 S 2 ，z p ＝ρ p c p S p ，z 1 、z 2 And z p Respectively representing the equivalent mechanical impedance of the front cover plate, the rear cover plate and the piezoelectric ceramic crystal stack.
When designing a transducer with a given eigenfrequency, if the materials and cross-sectional areas of the front and rear cover plates of the transducer, and the materials and dimensions of the piezoelectric ceramic stack are known, they can be determined according to the general knowledgeDirectly calculating the length l of the rear cover plate 2 And because of the presence of F and l in equation (1) 1 The two unknowns cannot be directly solved, and parameter scanning can be performed by means of MATLAB in combination with the formula (3), so that the size of the front cover plate which can meet the formula (2) and enable the vibration ratio to be maximum is solved.
For example, if a conventional sandwich type longitudinal vibration piezoelectric transducer with a resonance frequency of 690Hz is designed, the material of the back cover plate is selected to have a density of 8960kg/m 3 The radius of the cross section is 87mm, the piezoelectric ceramic crystal stack consists of 22 piezoelectric ceramic rings made of PZT-8, the outer radius of each piezoelectric ceramic ring is 30mm, the inner radius is 15mm, the height is 10mm, and the density of the front cover plate material is 2800kg/m 3 The radius of the section of the front cover plate, which is in contact with the piezoelectric ceramic stack, is 30mm, the length of the rear cover plate of the transducer, calculated according to formulas (1) - (3), is 0.54m, the length of the front cover plate is 1.48m, the radius of the radiation end face is 38.6mm, and then the whole length of the transducer is 2.24m. Because the transducer is long and the back cover plate has a large mass of about 114kg, and the front cover plate has a small diameter and a light mass, if the transducer is directly applied to oil well communication, the problems of difficult and unstable installation occur, and the transducer is too large in size, resulting in high manufacturing cost.
In order to reduce the size of the transducer, the transducer designed by the invention is based on the traditional sandwich type longitudinal vibration piezoelectric transducer structure, the front cover plate and the rear cover plate are designed into a nested type, and the equivalent mass and the equivalent length of the front cover plate and the rear cover plate are increased under the condition of not increasing the actual length of the transducer, thereby overcoming the contradiction between small size and low frequency. And lead with higher density and mass is adopted as the material of the inner cover plate in the nested rear cover plate, compared with the case of using copper as the material of the rear cover plate, the size of the transducer can be further reduced, and the vibration ratio can be improved.
The specific dimensions of the transducer in this embodiment are: the diameter of the cylindrical inner cover plate in the nested rear cover plate is 57mm, the height is 180mm, the outer diameter of the cylindrical outer cover plate is 87mm, the wall thickness of the barrel is 24mm, and the height is 320mm; the piezoelectric ceramic crystal stack comprises 22 piezoelectric ceramic rings made of PZT-8, the outer radius of each piezoelectric ceramic ring is 30mm, the inner radius is 15mm, and the height is 10mm; the radius of the cylindrical part of the nested front cover plate is 30mm, the height is 40mm, the radius of the upper bottom surface of the first trapezoid round table part is 30mm, the radius of the lower bottom surface is 80mm, the height is 420mm, the outer diameter of the round barrel structure part is 127mm, the barrel wall thickness is 32mm, and the height is 220mm; the radius of the upper bottom surface of the second trapezoid round table part is 127mm, the radius of the lower bottom surface is 60mm, and the height is 50mm; the radius of the disc at the top of the flange plate is 150mm, the thickness of the disc is 15mm, the outer diameter of the middle barrel part is 127mm, the wall thickness of the barrel is 15mm, and the radius of the bottom plug is 38mm. The whole height of the transducer is about 1m, the whole mass is about 85kg, and the transducer can be directly arranged on the top of an oil well pipeline through a flange plate for acoustic wave communication.
Fig. 4 shows the vibration mode of the transducer designed by the invention at the eigenfrequency 690Hz, and the deformation of the transducer can show that the mode almost only has displacement in the Z direction, so that the mode is the longitudinal vibration mode of the transducer, wherein the displacement of the nested front cover plate is larger, the displacement of the nested rear cover plate is smaller, and the fact that most of energy of the transducer is efficiently radiated from the nested front cover plate is shown.
In practical application, the frequency of the transmissible acoustic pass band may be different due to different structures and sizes of different pipelines, so that the optimal communication frequency needs to be selected according to practical situations, when the transducer designed by the invention is used as a signal source, the resonant frequency can be conveniently changed by adjusting the height of the cylindrical inner cover plate in the nested back cover plate, as shown in fig. 5, when the height of the cylindrical inner cover plate is increased from 130mm to 230mm, the resonant frequency of the transducer is reduced from 740Hz to 650Hz, and the height of the cylindrical inner cover plate is inversely proportional to the resonant frequency of the transducer.
The flange joint designed by the invention can effectively couple sound wave energy generated by the transducer to a communication load, reduce the influence of the load on the intrinsic frequency and impedance characteristics of the transducer, and take the load of a long metal pipeline as an example to illustrate the effect of the flange joint, wherein the material for arranging the metal pipeline in simulation is steel. When the transducer is connected with the flange joint and the metal pipeline, the length of the connecting pipeline is changed, so that a change curve of the intrinsic frequency of the transducer along with the length of the pipeline is obtained, as shown in fig. 6, the intrinsic frequency of the transducer periodically changes along with the length of the connecting pipeline, and the intrinsic frequency of the transducer changes near 690Hz, wherein the frequency deviation is not more than 30Hz, namely, the frequency deviation is at most 4%, the change is small, and the effectiveness of the added flange joint structure is proved. The reason for this periodic variation is that the long pipe is a periodic structure for low frequency acoustic signals, and its acoustic impedance is periodically varied. The sound velocity of the sound wave in the steel pipe is about 5100m/s, the wavelength is about 7.4m for a sound wave signal with a frequency of 690Hz, and the variation period of the acoustic impedance is half a wavelength, i.e., 3.7m, corresponding to the variation period in fig. 6.
When the transducer is connected to a 5m long pipe through a flange joint, the vibration mode of the transducer is shown in fig. 7, the intrinsic frequency of the transducer is 689.5Hz, the intrinsic frequency of the transducer is slightly shifted, the maximum displacement is still concentrated on the front cover plate of the transducer, and a joint surface is formed at the connection position of the lower surface of the flange plate and the plug. As shown in fig. 8, when the flange plate and the 5m long pipeline are connected and the flange joint and the pipeline are not connected, the admittance of the transducer changes along with the frequency, wherein the frequency corresponding to the maximum value of the admittance is the resonant frequency, and the admittance corresponding to the resonant frequency is 0.062S and 0.057S under the two conditions that the pipeline is not added and the pipeline is not added, which indicates that after the flange joint is added, the load has less influence on the intrinsic frequency and the impedance characteristic of the transducer.
To study the energy radiation efficiency of the transducer after the addition of the flange joint, the energy radiation efficiency was evaluated by comparing the Z-direction acceleration of the radiation surface of the nested front cover plate of the transducer with the Z-direction acceleration of the bottom of the pipe, as shown in FIG. 9, which is a spectrum of Z-direction acceleration detected at a point of the radiation surface of the nested front cover plate of the transducer and the bottom of the pipe, respectively, both of which have maxima at the resonance frequency, wherein the acceleration at the radiation surface of the front cover plate of the transducer is 120000m/s 2 The acceleration of the bottom of the pipeline is 51500m/s 2 After the transmission through the flange joint, the acceleration amplitude is attenuated by about 33%. Although the flange joint is added to cause certain radiation energy loss, the influence of the load on the intrinsic frequency and the impedance characteristic of the transducer is reduced, so that the transducer always keeps higher energy excitationThe efficiency of the transmission can be increased in practice by increasing the excitation signal power of the transducer to increase the intensity of the acoustic signal in the communication load.
Claims (6)
1. The low-frequency piezoelectric transducer integrating the flange joint and the nested front and rear cover plates is characterized by comprising a fastening nut (1), a prestress screw (2), an insulating sleeve (3), a nested rear cover plate, a piezoelectric ceramic crystal stack (6), a nested front cover plate (7) and a flange joint;
the embedded type low-frequency acoustic wave transducer comprises a fastening nut (1) and a nested front cover plate (7), wherein the fastening nut (1) and the nested front cover plate (7) are respectively and fixedly arranged at two ends of a prestress screw (2), an insulating sleeve (3) is sleeved on the outer circumferential side surface of the prestress screw (2), a nested rear cover plate and a piezoelectric ceramic crystal stack (6) which are sequentially arranged along the axial direction of the prestress screw (2) are sleeved on the outer circumferential side surface of the insulating sleeve (3), the fastening nut (1), the nested rear cover plate, the piezoelectric ceramic crystal stack (6) and the nested front cover plate (7) are sequentially and tightly arranged along the axial direction of the prestress screw (2), the nested front cover plate (7) is fixedly connected with one end of a flange plate of a flange joint, the prestress screw (2) and the flange joint are respectively arranged at two ends of the nested front cover plate (7), and the end of the flange joint is used as a radiation end of a low-frequency piezoelectric transducer;
the nested front cover plate (7) consists of a cylinder, a first trapezoid round table, a barrel-shaped connecting piece and a second trapezoid round table, wherein one end face of the cylinder and the piezoelectric ceramic crystal stack (6) are tightly arranged, the other end face of the cylinder is fixedly connected with the upper bottom face of the first trapezoid round table, the lower bottom face of the first trapezoid round table is fixedly connected with the inner bottom face of the barrel-shaped connecting piece, the outer bottom face of the barrel-shaped connecting piece is fixedly connected with the lower bottom face of the second trapezoid round table, and the upper bottom face of the second trapezoid round table is fixedly connected with the flange plate end of the flange joint.
2. The low-frequency piezoelectric transducer integrated with the flange joint and the nested front and rear cover plates according to claim 1, wherein the nested rear cover plate comprises a cylindrical inner cover plate (4) and a cylindrical outer cover plate (5), the cylindrical inner cover plate (4) is arranged in the cylindrical outer cover plate (5), the outer circumferential side surface of the cylindrical inner cover plate (4) and the inner circumferential side surface of the cylindrical outer cover plate (5) are arranged at intervals, through holes are formed in the middle parts of the cylindrical inner cover plate (4) and the cylindrical outer cover plate (5), the cylindrical inner cover plate (4) and the cylindrical outer cover plate (5) are tightly sleeved on the outer circumferential side surface of the insulating sleeve (3), the fastening nuts (1), the bottom of the cylindrical outer cover plate (5) and the cylindrical inner cover plate (4) are sequentially and tightly arranged along the axial direction of the prestress screw (2), the top of the cylindrical outer cover plate (5) extends to the cylindrical inner cover plate (4), and the other end surface of the cylindrical inner cover plate (4) is tightly arranged between the piezoelectric ceramic crystal stack (6).
3. The low-frequency piezoelectric transducer integrated with the flange joint and the nested front and rear cover plates according to claim 1, wherein the piezoelectric ceramic crystal stack (6) comprises piezoelectric ceramic circular rings and electrode plates, a plurality of piezoelectric ceramic circular rings are sequentially stacked, one electrode plate is arranged between every two adjacent piezoelectric ceramic circular rings, each electrode plate is connected with a lead, the polarization directions of the two adjacent piezoelectric ceramic circular rings are opposite, the piezoelectric ceramic circular rings and the electrode plates are sleeved on the outer circumferential side surface of the insulating sleeve (3), and the electrode plates arranged at two ends are respectively and tightly arranged with the nested rear cover plate and the nested front cover plate (7).
4. The low frequency piezoelectric transducer of claim 1 wherein the diameter of the lower base of the first trapezoidal land is less than the diameter of the inner base of the barrel connector.
5. The low-frequency piezoelectric transducer integrated with the flange joint and the nested front cover plate and the nested back cover plate according to claim 1, wherein the flange joint comprises a flange plate and a plug (11), one end face of the flange plate is fixedly connected with one end of the nested front cover plate (7), one end of the plug (11) is fixedly arranged in the middle of the other end face of the flange plate, the other end of the plug (11) serves as a radiation end of the low-frequency piezoelectric transducer and is used for connecting communication loads, and a cavity is formed in the flange plate.
6. The low-frequency piezoelectric transducer integrated with the flange joint and the nested front and rear cover plates according to claim 1, wherein the nested rear cover plates are made of metal materials with higher density, and the nested front cover plates (7) are made of metal materials with lower density.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101998201A (en) * | 2010-11-22 | 2011-03-30 | 哈尔滨工程大学 | Folding cover plate broadband underwater transducer |
| CN103521423A (en) * | 2013-09-29 | 2014-01-22 | 天津大学 | High-frequency piezoelectric ultrasonic transducer used for integrated circuit thermosonic bonding equipment |
| CN207154077U (en) * | 2017-02-23 | 2018-03-30 | 重庆西山科技股份有限公司 | Ultrasonic transducer |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6222305B1 (en) * | 1999-08-27 | 2001-04-24 | Product Systems Incorporated | Chemically inert megasonic transducer system |
| US7105985B2 (en) * | 2001-04-23 | 2006-09-12 | Product Systems Incorporated | Megasonic transducer with focused energy resonator |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101998201A (en) * | 2010-11-22 | 2011-03-30 | 哈尔滨工程大学 | Folding cover plate broadband underwater transducer |
| CN103521423A (en) * | 2013-09-29 | 2014-01-22 | 天津大学 | High-frequency piezoelectric ultrasonic transducer used for integrated circuit thermosonic bonding equipment |
| CN207154077U (en) * | 2017-02-23 | 2018-03-30 | 重庆西山科技股份有限公司 | Ultrasonic transducer |
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