Ultrasonic transducer and pretightening force accurate control method thereof

Abstract

The invention relates to the field of medical instruments, in particular to an ultrasonic transducer and a pretightening force accurate control method thereof. The ultrasonic transducer comprises an outer shell, a front cover plate, an amplitude-change pole, a fastening assembly, a connecting rod and a clamping assembly, piezoelectric ceramic crystal piles and electrode plates are arranged in the outer shell at equal intervals, and the front cover plate used for fixing the piezoelectric ceramic crystal piles is arranged in the outer shell; an amplitude-change pole used for amplifying the amplitude is installed on the side, away from the piezoelectric ceramic crystal stack, of the front cover plate, and a fastening assembly is installed between the outer shell and the front cover plate. According to the ultrasonic transducer and the pre-tightening force accurate control method thereof, through the design of the fastening assembly, automatic control over pre-tightening force application is achieved, the micro motor drives the locking bolt, the pressure sensor is matched for monitoring pre-tightening pressure in real time, the consistency problem caused by the difference of the using force and angle of a torque wrench in manual operation is avoided, and the working efficiency is improved. The time consumed for adjusting the pre-tightening force is reduced, and the assembling qualification rate is increased.

Description

Technical Field

[0001] The present invention relates to the field of medical devices, and in particular to an ultrasonic transducer and a method for accurately controlling the preload force thereof. Background Art

[0002] Ultrasonic transducers, devices that convert high-frequency electrical energy into mechanical vibrations, are widely used in the medical device field. Their performance directly impacts the accuracy and safety of ultrasonic treatments and diagnostics. The structure of an ultrasonic transducer typically includes an outer shell, a piezoelectric ceramic stack, electrodes, a front cover, a horn, and locking bolts. These bolts apply a preload to secure these components, ensuring efficient transmission of mechanical vibration and optimal piezoelectric ceramic operation.

[0003] Precise control of preload force is a key step in the assembly process of ultrasonic transducers. Excessive or insufficient preload force will significantly affect the performance and life of the transducer. In the current industry, the preload force control of ultrasonic transducers mostly relies on torque wrench adjustment. The operator observes the torque value of the digital torque wrench to determine whether the preload force meets the standard.

[0004] However, this method has significant limitations: different operators may have different operating forces and angles for the torque wrench. Even if the same torque wrench settings are used, the actual preload force applied may also be different. This uncertainty caused by human factors makes it difficult to ensure the control accuracy of the preload force. It is easy for overtightening to cause the ceramic piece to crack, or undertightening to reduce the resonance efficiency of the mechanical vibration, making it difficult to achieve precise adjustment and stable control of the preload force.

[0005] Therefore, it is necessary to provide a new ultrasonic transducer and a method for accurately controlling its preload force to solve the above technical problems. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides an ultrasonic transducer and a method for accurately controlling the preload force thereof.

[0007] The first aspect of the present application provides an ultrasonic transducer, comprising: an outer shell, a front cover, an amplitude rod, a fastening assembly, a connecting rod and a clamping assembly, wherein a piezoelectric ceramic crystal stack and an electrode sheet are equidistantly arranged inside the outer shell, a front cover for fixing the piezoelectric ceramic crystal stack is provided inside the outer shell, a mounting groove is provided inside the front cover, a pressure sensor is installed inside the mounting groove, an amplitude rod for amplifying the amplitude is installed on the side of the front cover away from the piezoelectric ceramic crystal stack, a fastening assembly is installed between the outer shell and the front cover, and the fastening assembly drives the front cover to move, which is equivalent to moving the piezoelectric ceramic The ceramic crystal stack and the electrode sheet are fixed together, and the fastening assembly includes: a micro motor and a locking bolt. The inner wall of the outer shell is fixedly connected to the micro motor, and the output end of the micro motor is fixedly connected to the square rod. The locking bolt is installed inside the outer shell, and a square groove is opened at one end of the locking bolt close to the micro motor. The square rod is placed inside the square groove and is slidably connected to the inner wall of the outer shell. A connecting rod for connecting an ultrasonic probe is installed at the end of the amplitude rod, and a clamping assembly is installed inside the connecting rod. The clamping assembly is used to quickly clamp and release the connecting rod and the ultrasonic probe.

[0008] In one embodiment, the fastening assembly also includes: a rear cover plate and a spring 1, the outer wall of the locking bolt is provided with a spring 1, one end of the spring 1 contacts the outer wall of the locking bolt close to the micro motor, the outer wall of the locking bolt is provided with a rear cover plate, and the side wall of the rear cover plate contacts the other end of the spring 1.

[0009] In one embodiment, a thread groove is formed inside one end of the amplitude transformer close to the locking bolt and is threadedly connected to the locking bolt, and a side of the front cover close to the micro motor contacts the electrode sheet.

[0010] In one embodiment, the outer wall of the front cover is symmetrically provided with limiting grooves, the inner wall of the outer shell is symmetrically fixedly connected with limiting rods, and the limiting rods are placed inside the corresponding limiting grooves and are slidably connected to the inner wall.

[0011] In one embodiment, the clamping assembly includes: a driving block, a push rod and a tension spring. The end of the outer shell away from the micro motor is threadedly connected to the connecting shell. The outer wall of the connecting shell is symmetrically provided with placement grooves. The inner wall of the placement groove is fixedly connected to the tension spring. The other end of the tension spring is fixedly connected to the driving block. The driving block is slidably connected to the inner wall of the corresponding placement groove. The opposite side of the driving block is fixedly connected to an inclined push rod.

[0012] In one embodiment, a first trapezoidal block is symmetrically and slidingly connected to the inside of one end of the amplitude variable rod close to the driving block, and a connecting plate is fixedly connected to the opposite side of the first trapezoidal block. A fixed rod is fixedly connected to the inside of the amplitude variable rod, and both ends of the fixed rod pass through the inside of the corresponding connecting plate and are slidably connected to its inner wall.

[0013] In one embodiment, a second spring is sleeved on the outer wall of the fixing rod, both ends of the second spring are in contact with the side walls of the corresponding connecting plate, a second trapezoidal block is symmetrically and slidably connected to the inside of the connecting rod, and an end of the connecting plate away from the first trapezoidal block is fixedly connected to the side wall of the corresponding second trapezoidal block.

[0014] In one embodiment, the inner wall of the connecting shell is symmetrically fixedly connected with a slide rail, and the outer wall of the amplitude transformer is symmetrically fixedly connected with a protrusion, which is placed inside the slide rail and slidably connected to the inner wall thereof.

[0015] In one embodiment, spring 1 and spring 2 are both compression springs.

[0016] A second aspect of the present application provides a method for accurately controlling the preload force of an ultrasonic transducer, which is applied to the ultrasonic transducer described in any one of the first aspects, and the specific steps are as follows: S1. Pass the locking bolt through the rear cover, piezoelectric ceramic crystal stack, electrode sheet, and front cover in sequence, and connect it to the threaded groove of the horn, ensuring that the surfaces of each component are in close contact. Drive the locking bolt to connect to the micro motor through the fit of the square rod and the square groove; S2. Discharge the piezoelectric ceramic crystal stack to release the initial charge accumulated during the assembly process to avoid interference with voltage monitoring during the preload process; S3, start the micro motor to drive the locking bolt to tighten, and apply a gradually increasing pre-tightening force to the piezoelectric ceramic crystal stack through the front cover. At the same time, use an oscilloscope to monitor the boundary voltage change curve of the piezoelectric ceramic crystal stack in real time, so that the voltage has a linear relationship with the externally applied pre-tightening force and meets the requirements. ; Wherein, U is the boundary voltage of the piezoelectric ceramic crystal stack, d is the thickness of the piezoelectric ceramic sheet, N is the number of piezoelectric ceramic sheets, A is the area of ​​the piezoelectric ceramic sheet, C m is the parallel capacitance of the piezoelectric ceramic crystal stack, and T is the preload force applied to the piezoelectric ceramic crystal stack; S4. Observe the voltage curve displayed on the oscilloscope. At the same time, the pressure sensor in the front cover monitors the value of the preload in real time. When the voltage changes from the linear region to the nonlinear region, it is determined that the preload has reached the qualified window. At this time, the micro motor stops driving, and the elastic force of spring 1 and the thread locking force of the locking bolt jointly maintain the stability of the preload.

[0017] Compared with the related prior art, the ultrasonic transducer and the method for precise control of preload force provided by the present invention have the following beneficial effects: Through the design of the fastening components, automatic control of preload is achieved. The micro motor drives the locking bolt, and the pressure sensor is used to monitor the preload pressure. This avoids consistency issues caused by differences in torque wrench force and angle during manual operation, reduces the time spent on preload adjustment, and improves the assembly qualification rate. By using the linear relationship between the voltage and preload of the piezoelectric ceramic stack and real-time monitoring of the voltage curve using an oscilloscope, the traditional control method that relies on a torque wrench and operator experience is replaced. This avoids preload deviations caused by insufficient torque wrench accuracy and differences in friction coefficients between components, effectively improving preload control accuracy. The design of the snap-on assembly enables quick assembly and disassembly of the ultrasonic probe, avoiding the tediousness of traditional bolt connections and loosening due to vibration during use, further improving the working efficiency and reliability of the transducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic structural diagram of the ultrasonic transducer provided by the present invention; Figure 2 for Figure 1 A schematic structural diagram of the outer shell section shown; Figure 3 for Figure 2 The structural diagram of the front cover shown; Figure 4 for Figure 3 The structural diagram of A shown; Figure 5 for Figure 3 The structural diagram of B shown; Figure 6 for Figure 3 The schematic diagram of the structure of the horn shown; Figure 7 for Figure 6 The structural diagram of C shown; Figure 8 Schematic diagram of the deformation of the piezoelectric ceramic crystal stack when an external force is applied; Figure 9 Schematic diagram of the method for measuring piezoelectric ceramic voltage using an oscilloscope; Figure 10 This is a schematic diagram of the real-time voltage curve of the piezoelectric ceramic crystal stack oscilloscope.

[0019] Numbers in the figure: 1. Outer shell; 2. Piezoelectric ceramic crystal stack; 3. Electrode sheet; 4. Front cover; 5. Amplitude transformer; 6. Connecting rod; 7. Micro motor; 8. Locking bolt; 9. Rear cover; 10. Square rod; 11. Square slot; 12. Spring 1; 13. Pressure sensor; 14. Limiting slot; 15. Limiting rod; 16. Driving block; 17. Push rod; 18. Tension spring; 19. Connecting shell; 20. First trapezoidal block; 21. Connecting plate; 22. Fixing rod; 23. Spring 2; 24. Second trapezoidal block; 25. Slide rail; 26. Bump. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] Ultrasonic transducers use preloaded bolts to tightly secure components, ensuring efficient transmission of mechanical vibrations and optimal operating conditions for the piezoelectric ceramics. Excessive or insufficient preload can affect transducer performance. Excessive preload can cause piezoelectric ceramics to crack, despite their high compressive strength. Furthermore, excessive preload increases internal stress in the material, potentially altering the piezoelectric ceramic's elastic modulus, affecting the transducer's resonant frequency and electromechanical coupling efficiency. Excessive stress can also cause plastic deformation or fatigue damage in the bolts and surrounding metal components, impacting long-term stability. Insufficient preload can cause the piezoelectric ceramics to crack due to tensile stress. Furthermore, the relative motion between components during vibration generates friction and wear, potentially impacting the transducer's long-term life. During dynamic operation, insufficient preload can also cause mechanical loosening, leading to unstable resonant frequency and even abnormal vibration modes, impacting the transducer's output performance.

[0022] During the assembly process, if the preload is applied improperly, such as without staged loading or if the torque control tool lacks precision, the actual preload value can deviate significantly from the theoretical value. In this case, even if the appropriate preload range is calculated during design, the assembled transducer may not achieve the expected performance indicators, such as resonant frequency shift, reduced Qm value, and insufficient output power.

[0023] The effects of inaccurate preload control can be summarized as follows: material damage (ceramic cracking, metal fatigue), energy loss (contact resistance, friction loss), performance instability (resonant frequency shift, abnormal vibration mode), shortened life (wear, fatigue accumulation), and increased temperature sensitivity. These effects not only affect the transducer's immediate performance but also its reliability and service life. Therefore, precise preload control is crucial to the performance, reliability, and lifespan of sandwich transducers.

[0024] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0025] Example 1 See also Figures 1 to 10, an ultrasonic transducer, the ultrasonic transducer includes: an outer shell 1, a front cover plate 4, an amplitude rod 5, a fastening assembly, a connecting rod 6 and a clamping assembly, a piezoelectric ceramic crystal stack 2 and an electrode sheet 3 are equidistantly arranged inside the outer shell 1, a front cover plate 4 for fixing the piezoelectric ceramic crystal stack 2 is provided inside the outer shell 1, a mounting groove is opened inside the front cover plate 4, a pressure sensor 13 is installed inside the mounting groove, a amplitude rod 5 for amplifying the amplitude is installed on the side of the front cover plate 4 away from the piezoelectric ceramic crystal stack 2, a fastening assembly is installed between the outer shell 1 and the front cover plate 4, and the fastening assembly drives the front cover plate 4 to move to fix the piezoelectric ceramic crystal stack 2 and the electrode sheet 3 together, the fastening assembly includes: a micro motor 7 and a locking bolt 8, the inner wall of the outer shell 1 is fixedly connected to the micro motor 7, and a small battery is installed inside the outer shell 1 for powering the micro motor 7, the output end of the micro motor 7 is fixedly connected to the square rod 10, and a locking bolt 8 is installed inside the outer shell 1, and the locking bolt 8 is close to the micro A square groove 11 is provided at one end of the motor 7, and the square rod 10 is placed inside the square groove 11 and is slidably connected to its inner wall. A connecting rod 6 for connecting an ultrasonic probe is installed at the end of the horn 5, and a clamping assembly is installed inside the connecting rod 6. The clamping assembly is used to quickly clamp and release the connecting rod 6 and the ultrasonic probe. The fastening assembly also includes: a rear cover plate 9 and a spring 12. The outer wall of the locking bolt 8 is sleeved with a spring 12, and one end of the spring 12 contacts the outer wall of the locking bolt 8 close to the end of the micro motor 7. The outer wall of the locking bolt 8 is sleeved with a rear cover plate 9, and the side wall of the rear cover plate 9 contacts the other end of the spring 12. A threaded groove is provided inside the end of the horn 5 close to the locking bolt 8 and is threadedly connected to the locking bolt 8. The side of the front cover plate 4 close to the micro motor 7 contacts the electrode sheet 3, and the outer wall of the front cover plate 4 is symmetrically provided with a limiting groove 14. The inner wall of the outer shell 1 is symmetrically fixed with a limiting rod 15, and the limiting rod 15 is placed inside the corresponding limiting groove 14 and is slidably connected to its inner wall.

[0026] The precise control method of the preload force of the ultrasonic transducer includes the following specific steps: S1. Pass the locking bolt 8 through the rear cover plate 9, the piezoelectric ceramic crystal stack 2, the electrode sheet 3 and the front cover plate 4 in sequence, and connect it with the threaded groove of the amplitude transformer 5 to ensure that the surfaces of each component are in close contact. Through the cooperation of the square rod 10 and the square groove 11, drive the locking bolt 8 to connect with the micro motor 7.

[0027] S2. Discharging the piezoelectric ceramic crystal stack 2 to release the initial charge accumulated during the assembly process to avoid interference with voltage monitoring during the pre-tightening process.

[0028] S3, start the micro motor 7 to drive the locking bolt 8 to tighten, and apply a gradually increasing pre-tightening force to the piezoelectric ceramic crystal stack 2 through the front cover 4. At the same time, use an oscilloscope to monitor the boundary voltage change curve of the piezoelectric ceramic crystal stack 2 in real time, so that the voltage has a linear relationship with the externally applied pre-tightening force and meets the requirements. , where U is the boundary voltage of the piezoelectric ceramic crystal stack, d is the thickness of the piezoelectric ceramic sheet, N is the number of piezoelectric ceramic sheets, A is the area of ​​the piezoelectric ceramic sheet, C m is the parallel capacitance of the piezoelectric ceramic crystal stack, and T is the preload force applied to the piezoelectric ceramic crystal stack.

[0029] S4. Observe the voltage curve displayed on the oscilloscope. At the same time, the pressure sensor 13 in the front cover 4 monitors the value of the preload in real time. When the voltage changes from the linear region to the nonlinear region, it is determined that the preload has reached the qualified window. At this time, the micro motor 7 stops driving. The elastic force of the spring 12 and the thread locking force of the locking bolt 8 jointly maintain the stability of the preload.

[0030] Ultrasonic transducers are sandwich transducers. From the perspective of mechanical and electrical boundary conditions, the second-type piezoelectric equation is applicable, as shown in the following equations (1) and (2):

[0031]

[0032] in, is the stress on the piezoelectric ceramic, is the strain corresponding to the stress, is the elastic modulus of the piezoelectric ceramic, is the electric displacement, is the electric field strength, is the absolute dielectric constant, is the piezoelectric stress constant, which is the inverse of the pressure strain constant.

[0033] For a piezoelectric ceramic piece vibrating longitudinally, the force diagram is as follows Figure 8 As shown, its linear one-dimensional motion equation is shown in formula (3):

[0034] in: is the stress on the piezoelectric ceramic, is the density of piezoelectric ceramics, is the particle displacement, is the coordinate of the particle, t is the time variable The mechanical boundary conditions are:

[0035] in, is the thickness of the piezoelectric ceramic, is the thickness variation of the piezoelectric ceramic The one-dimensional wave equation (3) is applied under static load The motion equation when is shown in formula (5):

[0036] in, is the electric potential, which indicates the change of electromotive force during the deformation of the piezoelectric ceramic piece The electrical boundary conditions are:

[0037] in, Boundary voltage Combining the second kind of piezoelectric equations (1) and (2), the matrix can be simplified as follows:

[0038] in: is the area of ​​the piezoelectric ceramic, For static load, For static load The boundary voltage under the action of is the charge of the piezoelectric ceramic, is the capacitance of the piezoelectric ceramic under clamping conditions,

[0039] The free capacitance of the piezoelectric ceramic is

[0040] During the bolt pre-tightening process, Figure 4 As shown, the parallel capacitors The charge stored on is:

[0041] According to equations (5), (7), and (9), for a crystal stack composed of N pieces of piezoelectric ceramics, the applied stress When As shown in formula (10):

[0042] According to formula (10), the boundary voltage of piezoelectric ceramics is With externally applied stress It is a linear relationship with the number of piezoelectric ceramics , piezoelectric ceramic thickness , piezoelectric ceramic area Proportional to the capacitance in parallel with the piezoelectric ceramic crystal stack By displaying the piezoelectric ceramic crystal stack voltage in real time on an oscilloscope, it is possible to accurately determine whether the current preload force is within the qualified window. Therefore, the preload force during the assembly process can be precisely controlled by monitoring the piezoelectric ceramic crystal stack voltage. Figure 10 As stated.

[0043] In summary: 1. By providing a functional relationship between piezoelectric ceramic voltage and preload force, the piezoelectric ceramic boundary voltage is linearly related to the externally applied stress and is proportional to the number of piezoelectric ceramic sheets, the thickness of the piezoelectric ceramic sheets, and the area of ​​the piezoelectric ceramic sheets.

[0044] 2. By controlling the piezoelectric ceramic voltage to determine whether the preload force has reached the target torque, torque errors caused by torque wrench accuracy issues are avoided.

[0045] 3. The different friction coefficients of different transducer components will result in a wider range of torque during the pre-tightening process. By monitoring the piezoelectric ceramic voltage to determine the pre-tightening force, the influence of different friction coefficients between transducer components is avoided, and the torque can be accurately controlled within a narrower range.

[0046] 4. By displaying the voltage curve of the piezoelectric ceramic crystal stack 2 in real time on an oscilloscope, the changing trend of the applied preload can be accurately determined, and the target preload can be controlled more precisely, greatly improving the qualified rate of ultrasonic transducer assembly.

[0047] Example 2 See also Figure 3 、 Figures 6 and 7 , the clamping assembly includes: a driving block 16, a push rod 17 and a tension spring 18. The end of the outer shell 1 away from the micro motor 7 is threadedly connected to the connecting shell 19. The outer wall of the connecting shell 19 is symmetrically provided with a placement groove. The inner wall of the placement groove is fixedly connected with a tension spring 18. The other end of the tension spring 18 is fixedly connected to the driving block 16. The driving block 16 is slidably connected to the inner wall of the corresponding placement groove. The opposite side of the driving block 16 is fixedly connected with an inclined push rod 17. The end of the amplitude rod 5 close to the driving block 16 is symmetrically slidably connected to the first trapezoidal block 20. The opposite side of the first trapezoidal block 20 is fixedly connected to the connecting plate 21. The interior of the amplitude rod 5 is fixedly connected with The fixing rod 22 has two ends passing through the interior of the corresponding connecting plate 21 and slidingly connected to the inner wall thereof. The outer wall of the fixing rod 22 is sleeved with a spring 23. Both ends of the spring 23 are in contact with the side walls of the corresponding connecting plate 21. The interior of the connecting rod 6 is symmetrically slidably connected with a second trapezoidal block 24. One end of the connecting plate 21 away from the first trapezoidal block 20 is fixedly connected to the side wall of the corresponding second trapezoidal block 24. The inner wall of the connecting shell 19 is symmetrically fixedly connected with a slide rail 25. The outer wall of the amplitude variable rod 5 is symmetrically fixedly connected with a protrusion 26. The protrusion 26 is placed inside the slide rail 25 and slidingly connected to its inner wall. Both spring 12 and spring 23 are compression springs.

[0048] The working principles of the ultrasonic transducer and preload control method provided by the present invention are as follows: Initial assembly and connection: Align the square groove 11 at the end of the locking bolt 8 with the square rod 10 at the output end of the micro motor 7, so that the square rod 10 is fully inserted into the square groove 11 to form a transmittable rigid connection, ensuring that the torque of the micro motor 7 can be accurately transmitted to the locking bolt 8; a spring 12 is sleeved on the outer wall of the locking bolt 8, and one end of the spring 12 is in contact with the end step of the locking bolt 8; then the rear cover plate 9 is sleeved in sequence, so that the side wall of the rear cover plate 9 is in close contact with the other end of the spring 12.

[0049] Continue to install the piezoelectric ceramic crystal stack 2, electrode sheet 3 and front cover plate 4 along the axial direction of the locking bolt 8, ensuring that the central axes of the components are aligned and the contact surfaces are free of impurities; insert the horn 5 into the interior of the front cover plate 4, and the threaded end of the locking bolt 8 passes through the front cover plate 4 and contacts the thread groove of the horn 5, completing the preliminary assembly; During the assembly process, the limit rod 15 on the inner wall of the outer shell 1 needs to be accurately embedded in the limit groove 14 on the outer wall of the front cover plate 4 to form an axial guide structure to limit the circumferential rotation of the front cover plate 4 and the amplitude transformer 5, ensuring that only axial displacement occurs during the subsequent pre-tightening process.

[0050] Preload application and monitoring: Start the micro motor 7, and its output end drives the locking bolt 8 to rotate through the cooperation of the square rod 10 and the square groove 11; at the same time, it pushes the amplitude variable rod 5, so that the locking bolt 8 passes through the front cover plate 4 and contacts the internal thread groove of the amplitude variable rod 5. Under the rotation of the micro motor 7, the locking bolt 8 is threadedly connected to the amplitude variable rod 5. Since the front cover plate 4 cannot rotate due to the constraint of the limiting rod 15, the rotation of the locking bolt 8 will drive the amplitude variable rod 5 and the front cover plate 4 to move along the axial direction of the locking bolt 8.

[0051] During the movement of the front cover plate 4, the electrode sheet 3 and the piezoelectric ceramic crystal stack 2 are gradually squeezed, and the rear cover plate 9 is pushed to compress the spring 12. At this time, the pressure between the front cover plate 4 and the electrode sheet 3 is transmitted to the pressure sensor 13, and the pressure sensor 13 converts the pressure signal into an electrical signal output in real time for real-time monitoring of the preload value.

[0052] At the same time, the piezoelectric ceramic crystal stack 2 is connected to an oscilloscope through a wire, and the oscilloscope displays the boundary voltage change curve of the crystal stack in real time; according to the principle of piezoelectric effect, the voltage is linearly related to the externally applied preload (in accordance with the functional relationship ), in the linear stage, the voltage rises steadily with the increase of preload force.

[0053] Preload stability control: When the monitoring value of the pressure sensor 13 reaches the preset threshold, the voltage curve displayed by the oscilloscope enters the nonlinear region from the linear region, indicating that the preload force reaches the designed qualified window. At this time, the control system immediately stops driving the micro motor 7 to avoid excessive increase in the preload force.

[0054] After stopping, the rebound force of spring 12 and the thread self-locking force of the locking bolt 8 form a balance, jointly maintaining the stability of the preload force; the elastic buffering effect of spring 12 can offset the tiny stress fluctuations caused by vibration or temperature changes, ensuring that the piezoelectric ceramic crystal stack 2 is always in the best stress state.

[0055] Then, the connecting shell 19 is put on the outside of the amplitude transformer 5, so that the connecting rod 6 at the end of the amplitude transformer 5 passes through the connecting shell 19. At the same time, the protrusion 26 fixed on the outer wall of the amplitude transformer 5 is placed inside the slide rail 25 inside the connecting shell 19, so that the top rod 17 fixed on the side wall of the driving block 16 corresponds to the first trapezoidal block 20 sliding inside the amplitude transformer 5, ensuring the subsequent normal operation of the snap-on assembly. Then, the connecting shell 19 and the outer shell 1 are connected together by threads. During this process, the half of the amplitude transformer 5 close to the connecting rod 6 rotates together with the connecting shell 19, and finally the connecting shell 19 and the outer shell 1 are fastened together to complete the assembly.

[0056] When the ultrasound probe needs to be replaced, the driving block 16 connected to the outer wall of the shell 19 is pushed toward the connecting rod 6. The driving block 16 slides along the inner wall of the placement groove and stretches the tension spring 18, while driving the inclined top rods 17 to move synchronously. The end of the top rod 17 contacts the inclined surface of the first trapezoidal block 20 in the amplitude rod 5 and generates a lateral thrust, causing the two first trapezoidal blocks 20 to slide toward each other along the inner wall of the amplitude rod 5.

[0057] The first trapezoidal block 20 drives the second trapezoidal block 24 to move synchronously toward each other through the connecting plate 21. The connecting plate 21 slides axially along the fixed rod 22 and compresses the spring 23. When the second trapezoidal block 24 is completely retracted into the connecting rod 6, its card connection with the ultrasonic probe slot is released, and the ultrasonic probe can be directly pulled out.

[0058] After releasing the driving block 16, the tension of the tension spring 18 resets the driving block 16 and the push rod 17; the elastic force of the second spring 23 pushes the connecting plate 21, the first trapezoidal block 20 and the second trapezoidal block 24 to move in the opposite direction to the initial position, waiting for the next installation.

[0059] When installing a new ultrasound probe, align the connecting end of the probe with the connecting rod 6 and insert it axially; during the insertion process, the end of the probe squeezes the inclined surface of the second trapezoidal block 24, forcing the second trapezoidal block 24 to shrink into the inside of the connecting rod 6, driving the connecting plates 21 to move toward each other and compressing the second spring 23.

[0060] When the probe is fully inserted and the internal slot corresponds to the position of the second trapezoidal block 24, the spring 23 releases its elastic force, pushing the connecting plate 21 and the second trapezoidal block 24 to move in opposite directions, and the second trapezoidal block 24 is embedded in the probe slot to form a firm connection; at this time, the tension spring 18 is in a natural state, and the driving block 16 and the push rod 17 are not subjected to force, ensuring that the connection structure is stable.

[0061] The preload adjustment system uses the closed-loop control of "motor drive-pressure monitoring-spring buffering" to ensure that the piezoelectric ceramic crystal stack 2 efficiently converts electrical energy into mechanical vibration under the optimal preload. The vibration is amplified by the amplitude rod 5 and then transmitted to the connecting rod 6 and the ultrasonic probe.

[0062] The quick-change system uses a "trapezoidal block transmission-spring return" mechanical structure to achieve non-destructive and rapid replacement of ultrasonic probes without affecting the stability of the preload adjustment system, further improving the working efficiency and reliability of the transducer.

[0063] The standard parts used in the present invention can all be purchased from the market, and special-shaped parts can be customized according to the description in the specification and drawings. The specific connection methods of each part adopt conventional means such as mature bolts, rivets, welding, etc. in the existing technology. The machinery, parts and equipment all adopt conventional models in the existing technology, and the circuit connection adopts the conventional connection method in the existing technology, which will not be described in detail here.

[0064] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An ultrasonic transducer, characterized in that: include: An outer shell (1), wherein piezoelectric ceramic crystal stacks (2) and electrode sheets (3) are equidistantly arranged inside the outer shell (1); A front cover plate (4) is provided inside the outer shell (1) for fixing the piezoelectric ceramic crystal stack (2), a mounting groove is provided inside the front cover plate (4), and a pressure sensor (13) is installed inside the mounting groove; A horn (5) for amplifying the amplitude is installed on a side of the front cover (4) away from the piezoelectric ceramic crystal stack (2); A fastening assembly is installed between the outer shell (1) and the front cover (4), and the fastening assembly fixes the piezoelectric ceramic crystal stack (2) and the electrode sheet (3) together when the fastening assembly drives the front cover (4) to move. The fastening assembly includes: a micro motor (7) and a locking bolt (8), the inner wall of the outer shell (1) is fixedly connected to the micro motor (7), the output end of the micro motor (7) is fixedly connected to the square rod (10), the inner part of the outer shell (1) is installed with a locking bolt (8), and a square groove (11) is provided at one end of the locking bolt (8) close to the micro motor (7), and the square rod (10) is placed inside the square groove (11) and is slidably connected to the inner wall thereof; A connecting rod (6) is installed at the end of the horn (5) for connecting to an ultrasonic probe; A clamping assembly is installed inside the connecting rod (6), and the clamping assembly is used to quickly clamp and release the connecting rod (6) and the ultrasonic probe.

2. The ultrasonic transducer according to claim 1, characterized in that The fastening assembly further comprises: a rear cover plate (9) and a spring 1 (12); the inner wall of the outer shell (1) is fixedly connected to the micro motor (7); the output end of the micro motor (7) is fixedly connected to the square rod (10); a locking bolt (8) is installed inside the outer shell (1); a square groove (11) is provided at one end of the locking bolt (8) close to the micro motor (7); the square rod (10) is placed inside the square groove (11) and is slidably connected to the inner wall thereof; a spring 1 (12) is sleeved on the outer wall of the locking bolt (8); one end of the spring 1 (12) contacts the outer wall of the end of the locking bolt (8) close to the micro motor (7); a rear cover plate (9) is sleeved on the outer wall of the locking bolt (8); a side wall of the rear cover plate (9) contacts the other end of the spring 1 (12).

3. The ultrasonic transducer according to claim 2, characterized in that A threaded groove is provided inside one end of the amplitude changing rod (5) close to the locking bolt (8) and is threadedly connected to the locking bolt (8). A side of the front cover plate (4) close to the micro motor (7) contacts the electrode sheet (3), and a mounting groove is provided inside the front cover plate (4). A pressure sensor (13) is installed inside the mounting groove.

4. The ultrasonic transducer according to claim 3, characterized in that The outer wall of the front cover (4) is symmetrically provided with limiting grooves (14), and the inner wall of the outer shell (1) is symmetrically fixedly connected with limiting rods (15). The limiting rods (15) are placed inside the corresponding limiting grooves (14) and are slidably connected to the inner wall.

5. The ultrasonic transducer according to claim 1, characterized in that The clamping assembly comprises: a driving block (16), a push rod (17) and a tension spring (18); one end of the outer shell (1) away from the micro motor (7) is threadedly connected to a connecting shell (19); the outer wall of the connecting shell (19) is symmetrically provided with placement grooves; the inner wall of the placement groove is fixedly connected to a tension spring (18); the other end of the tension spring (18) is fixedly connected to the driving block (16); the driving block (16) is slidably connected to the inner wall of the corresponding placement groove; and the opposite side of the driving block (16) is fixedly connected to an inclined push rod (17).

6. The ultrasonic transducer according to claim 5, characterized in that The first trapezoidal block (20) is symmetrically and slidably connected to the interior of one end of the amplitude changing rod (5) close to the driving block (16), and the opposite side of the first trapezoidal block (20) is fixedly connected to a connecting plate (21). The interior of the amplitude changing rod (5) is fixedly connected to a fixing rod (22), and both ends of the fixing rod (22) pass through the interior of the corresponding connecting plate (21) and are slidably connected to the inner wall thereof.

7. The ultrasonic transducer according to claim 6, characterized in that The outer wall of the fixing rod (22) is provided with a second spring (23), both ends of the second spring (23) are in contact with the side wall of the corresponding connecting plate (21), the interior of the connecting rod (6) is symmetrically slidably connected to the second trapezoidal block (24), and the end of the connecting plate (21) away from the first trapezoidal block (20) is fixedly connected to the side wall of the corresponding second trapezoidal block (24).

8. The ultrasonic transducer according to claim 5, characterized in that The inner wall of the connecting shell (19) is symmetrically fixedly connected to a slide rail (25), and the outer wall of the amplitude changing rod (5) is symmetrically fixedly connected to a protrusion (26), which is placed inside the slide rail (25) and slidably connected to the inner wall thereof.

9. The ultrasonic transducer according to claim 6, characterized in that: Spring 1 (12) and spring 2 (23) are both compression springs.

10. A method for accurately controlling the preload force of an ultrasonic transducer, characterized in that: Applied to the ultrasonic transducer according to any one of claims 1 to 8, the specific steps are as follows: S1. Pass the locking bolt (8) through the rear cover (9), the piezoelectric ceramic crystal stack (2), the electrode sheet (3) and the front cover (4) in sequence, and connect it with the threaded groove of the amplitude rod (5), ensuring that the surfaces of each component are in close contact. Drive the locking bolt (8) to connect with the micro motor (7) through the cooperation of the square rod (10) and the square groove (11); S2, performing a discharge process on the piezoelectric ceramic crystal stack (2) to release the initial charge accumulated during the assembly process to avoid interference with voltage monitoring during the pre-tightening process; S3, start the micro motor (7) to drive the locking bolt (8) to tighten, and apply a gradually increasing pre-tightening force to the piezoelectric ceramic crystal stack (2) through the front cover (4). At the same time, use an oscilloscope to monitor the boundary voltage change curve of the piezoelectric ceramic crystal stack (2) in real time, so that the boundary voltage has a linear relationship with the externally applied pre-tightening force and meets the requirements. ; Wherein, U is the boundary voltage of the piezoelectric ceramic crystal stack, d is the thickness of the piezoelectric ceramic sheet, N is the number of piezoelectric ceramic sheets, A is the area of ​​the piezoelectric ceramic sheet, C m is the parallel capacitance of the piezoelectric ceramic crystal stack, and T is the preload force applied to the piezoelectric ceramic crystal stack; S4. Observe the voltage curve displayed on the oscilloscope. At the same time, the pressure sensor (13) in the front cover (4) monitors the value of the preload in real time. When the voltage curve enters the nonlinear region from the linear region, it is determined that the preload has reached the qualified window and the driving of the micro motor (7) is stopped. The elastic force of the spring (12) and the thread locking force of the locking bolt (8) jointly maintain the stability of the preload.

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