Ultrasonic transducer connecting structure, connecting method and ultrasonic physiotherapy equipment

Abstract

The invention relates to an ultrasonic transducer connecting structure, a connecting method and ultrasonic physiotherapy equipment, and belongs to the technical field of physiotherapy equipment. A rigid mechanical bolting structure is adopted to replace a traditional gluing mode, and uniform axial pre-tightening force is applied to the piezoelectric ceramic element through cooperation of a bolt and a metal gasket, so that the negative electrode face of the piezoelectric ceramic element is in direct contact with the smooth bottom face of the inner side of the metal shell. According to the invention, the risk of performance attenuation caused by aging of an adhesive layer is eliminated, and the synchronism and stability of vibration energy transmission are ensured through uniform rigid coupling, so that sound field distortion and local hot spots are effectively inhibited, and the long-term reliability of connection and the uniformity of a sound field are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of physiotherapy equipment technology, and in particular to an ultrasonic transducer connection structure, connection method, and ultrasonic physiotherapy equipment. Background Technology

[0002] With the development of physiotherapy equipment technology, ultrasonic physiotherapy equipment using piezoelectric ceramic elements as vibration generators has emerged. This technology enables efficient electromechanical conversion to generate ultrasonic waves for treatment. To fix the piezoelectric ceramic element to the metal shell of the physiotherapy head and achieve electrical connection, conductive adhesive is commonly used in related technologies for bonding, whereby the piezoelectric ceramic is adhered to the inside of the shell using conductive adhesive.

[0003] However, the above-mentioned conductive adhesive bonding method has inherent defects in terms of reliability and acoustic performance: In terms of reliability, adhesives are prone to aging, creep, fatigue, and even decomposition under long-term mechanical vibration and operating temperature rise, which leads to gradual degradation of bonding strength and electrical properties, posing a risk of failure. This not only shortens the service life of equipment but may also introduce safety hazards. In terms of acoustic performance, the adhesive layer is prone to uneven thickness and stress distribution during curing and service. As a non-uniform viscoelastic medium, it will distort the transmission path of vibration energy, causing the mechanical coupling between the piezoelectric ceramic element and the shell to be spatially uneven and temporally unstable. This coupling state will cause phase distortion of the radiation wave front, generating random interference in the acoustic near field (Fresnel region) and forming a highly concentrated local focus of energy, which may cause burning or stinging of the patient's subcutaneous tissue, seriously affecting the treatment experience and safety. Summary of the Invention

[0004] In response to the shortcomings of the existing manufacturing technology, the applicant provides an ultrasonic transducer connection structure, connection method, and ultrasonic physiotherapy device, thereby simultaneously solving the problems of low connection reliability, easy performance attenuation, and near-field sound field distortion caused by uneven coupling in traditional adhesive methods, and comprehensively improving the product's service life, treatment safety, and comfort.

[0005] The technical solution adopted in this invention is as follows: An ultrasonic transducer connection structure, comprising: The metal casing has a smooth bottom surface perpendicular to the axial direction on its inner side; A piezoelectric ceramic element having a positive electrode surface, a negative electrode surface, and an electrode coating connected to the positive and negative electrode surfaces, wherein the negative electrode surface is disposed facing the smooth bottom surface of the metal casing; A connecting assembly configured to apply a spatially uniform axial preload to the positive electrode surface of the piezoelectric ceramic element, and through the preload, force the negative electrode surface of the piezoelectric ceramic element to form direct contact with the smooth bottom surface of the metal casing.

[0006] As a further improvement to the above technical solution: In one embodiment, the connection assembly includes: a metal gasket, the lower surface of which is in direct contact with the positive electrode surface of the piezoelectric ceramic element; a preload bolt; and an insulating bushing fitted onto the preload bolt. The preload bolt passes through the metal washer and the insulating bushing in sequence and is threaded to the metal housing so as to generate the axial preload force by tightening the preload bolt; the insulating bushing is used to electrically isolate the preload bolt from the metal washer and the piezoelectric ceramic element.

[0007] In one embodiment, the metal housing includes a housing base and a protrusion extending axially from the inner side of the housing base, the end of the preload bolt being threadedly connected to the protrusion.

[0008] In one embodiment, the contact area between the lower surface of the metal pad and the piezoelectric ceramic element is configured to cover the active area of ​​the positive electrode surface of the piezoelectric ceramic element.

[0009] In one embodiment, the magnitude of the axial preload is configured such that the minimum value is sufficient to eliminate the gap between the negative electrode surface of the piezoelectric ceramic element and the smooth bottom surface of the metal housing, and the maximum value is less than the compressive strength of the piezoelectric ceramic element, so as to maintain a long-term stable direct contact state under the rated operating conditions of the equipment.

[0010] In one embodiment, the minimum value of the axial preload satisfies the following: eliminating gaps at the contact interface and achieving effective sound energy transfer, the required interface pressure... for:

[0011] in, The equivalent elastic modulus of the contact material; For overall surface roughness; This refers to the characteristic contact dimension.

[0012] On the other hand, this application also provides an ultrasonic transducer connection method, applied to the above-mentioned ultrasonic transducer connection structure, the method comprising: The negative electrode surface of the piezoelectric ceramic element is placed facing the smooth bottom surface of the metal casing; Install the connection components; By operating the connecting assembly, a spatially uniform axial preload is applied to the positive electrode surface of the piezoelectric ceramic element, forcing the negative electrode surface of the piezoelectric ceramic element to form direct contact with the smooth bottom surface of the metal casing.

[0013] In one embodiment, the connection assembly includes a metal gasket, a preload bolt, and an insulating bushing; The process of installing the connecting assembly is as follows: the metal gasket is placed on the positive electrode surface of the piezoelectric ceramic element, and the pre-tightening bolt passes through the metal gasket and the insulating bushing sleeved thereon in sequence, and is then threadedly connected to the metal shell. The process of applying axial preload is as follows: tighten the preload bolt to the set torque to generate the axial preload.

[0014] In one embodiment, the set torque is configured such that the resulting axial preload is between 0.5 kN and 2.0 kN.

[0015] On the other hand, this application also provides an ultrasound physiotherapy device, including the ultrasound transducer connection structure as described above.

[0016] The beneficial effects of this invention are as follows: This invention features a compact structure that eliminates adhesives and employs an all-metal rigid bolted structure. By using a preset and controllable mechanical preload, the coupling between the piezoelectric ceramic element and the metal shell is maintained. This completely eliminates the risk of connection strength degradation and electrical performance deterioration caused by aging, creep, fatigue, or decomposition of the adhesive layer under long-term vibration and temperature rise. The mechanical connection method of this application can maintain the stability of the coupling state throughout the entire life cycle of the device, fundamentally improving the durability and safety reliability of the product.

[0017] This invention also has the following advantages: This invention achieves a direct and tight rigid mechanical coupling between the piezoelectric ceramic element and the outer shell without an intermediate viscoelastic layer through uniform axial preload and a smoothly machined bottom surface on the inner side of the metal shell. This coupling method ensures the spatial uniformity and temporal stability of vibration energy transmission from the piezoelectric ceramic to the radiating surface. Crucially, it excites a radiating wavefront with extremely high phase consistency, effectively avoiding wavefront phase distortion caused by uneven coupling. Therefore, it can significantly suppress harmful random interference and the formation of highly concentrated local focal points (hot spots) in the acoustic near field (treatment area), thereby creating a smooth and uniform acoustic energy distribution in the treatment area. This fundamentally reduces the risk of local overheating or stinging in the patient's subcutaneous tissue, greatly improving the safety and comfort of the treatment.

[0018] This invention achieves direct contact coupling through uniform preload, and has wide adaptability to the specific shape (such as circular, annular, rectangular, etc.) and arrangement (single piece or array) of piezoelectric ceramic elements. At the same time, the preload of this assembly process can be accurately calibrated and repeated by controlling the torque of the preload bolts. The process is simple and reliable, does not depend on the experience of the operators, and is conducive to ensuring the consistency of product performance under large-scale production. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of this application.

[0020] Figure 2 This is a cross-sectional view of the internal structure of this application.

[0021] Figure 3 This is a schematic diagram of a cylindrical piezoelectric ceramic element bonded with adhesive under existing technology in a 1MHz radiated acoustic field.

[0022] Figure 4 This is a schematic diagram of a ring-shaped piezoelectric ceramic element bonded with adhesive under existing technology in a 1MHz radiated acoustic field.

[0023] Figure 5 This is a schematic diagram of a bolted connection of a ring-shaped piezoelectric ceramic element in a 1MHz radiated acoustic field according to an embodiment of this application.

[0024] Among them: 100, metal shell; 200, piezoelectric ceramic element; 300, metal gasket; 400, insulating bushing; 500, bolt washer; 600, preload bolt; 110. Outer shell base; 120. Protrusion. Detailed Implementation

[0025] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0029] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0030] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides an ultrasonic transducer connection structure that abandons the traditional conductive adhesive bonding method and adopts a rigid mechanical bolt connection, aiming to solve the problems of connection reliability, long-term stability and acoustic performance uniformity at the same time.

[0031] In some embodiments, the ultrasonic transducer connection structure mainly includes three core parts: a metal shell 100 serving as the acoustic radiation surface and the basis of the electrical circuit, a piezoelectric ceramic element 200 serving as the electromechanical conversion core, and a set of connection components for achieving efficient electromechanical coupling. The connecting component is configured to apply a spatially uniform axial preload to the positive electrode surface of the piezoelectric ceramic element 200, which forces the negative electrode surface of the piezoelectric ceramic element 200 to form a direct and tight physical contact and electrical connection between it and the smooth bottom surface of the metal housing 100, which is precision machined without any intermediate adhesive layer.

[0032] In some embodiments, the metal shell 100 constitutes the main structure of the physiotherapy head. It is usually made of materials such as stainless steel or aluminum alloy that have good biocompatibility, high rigidity and excellent acoustic properties. It not only serves as a mechanical support and protective shell, but also plays a more crucial role as the radiation surface of ultrasound (i.e. the treatment contact surface) and the negative electrode of the electrical circuit. Furthermore, the outer shell base 110 of the metal shell 100 constitutes the main part of the shell, and its inner bottom surface (i.e. the side facing the piezoelectric ceramic element 200) is processed to form a smooth bottom surface perpendicular to the axial direction. The flatness of the bottom surface is usually required to be better than 5 μm, and the surface roughness Ra is not greater than 0.4 μm, in order to ensure that large-area uniform contact is achieved subsequently. Furthermore, a protrusion 120 is formed by extending axially (i.e., perpendicular to the bottom surface) from the center of the inner bottom surface of the outer shell base 110. The center of the protrusion 120 is machined with an internal threaded hole for cooperating with the preload bolt 600 in the connecting assembly, so that the point of application of the preload force is located on the central axis of the structure, which is beneficial to the symmetrical distribution of the force line.

[0033] In some embodiments, the piezoelectric ceramic element 200 is the source of ultrasonic vibration energy, and is typically made of piezoelectric ceramic materials such as PZT (lead zirconate titanate) series. Figure 2 As shown, the component has two planes that are axially opposite each other, defined as a positive electrode surface and a negative electrode surface, respectively; both surfaces are coated with a high conductivity electrode coating (e.g., a silver electrode) by sputtering, screen printing or other methods; the negative electrode surface is disposed facing the smooth bottom surface of the metal housing 100, while the positive electrode surface faces upward to connect to the excitation circuit.

[0034] It is understood that, in practical applications, the shape of the piezoelectric ceramic element 200 can be various geometric shapes such as circles, rings, and rectangles, or it can be an array of multiple elements.

[0035] In some embodiments, the connecting assembly is an actuator that enables rigid bolting and uniform force application, and mainly includes, from top to bottom, a preload bolt 600, a bolt washer 500, an insulating bushing 400, and a metal washer 300; Among them, the preload bolt 600, as a force-applying component, is usually made of high-strength stainless steel (such as A2-70 grade). Its screw part passes through the through holes on the metal washer 300, the insulating bushing 400 and the bolt washer 500 in sequence, and the end engages with the internal thread hole on the protrusion 120 of the metal housing 100. By tightening the preload bolt 600, a precise and controllable axial preload force can be generated. Among them, bolt washer 500 is a standard flat washer, which is placed under the head of pre-tightening bolt 600. Its function is to increase the force-bearing area, disperse the concentrated pressure applied to the bolt head, and prevent indentation or damage to adjacent parts during the tightening process. The insulating bushing 400 is made of engineering plastic with high insulation strength and high mechanical strength (such as polyimide PI or polyether ether ketone PEEK). It is tightly fitted on the threaded rod of the preload bolt 600 and located in the through hole of the metal washer 300 and the space above it. The insulating bushing 400 is used to achieve electrical isolation and ensure that the metal fastener, the preload bolt 600, is completely insulated from the metal washer 300 and the positive circuit of the piezoelectric ceramic element 200 to prevent short circuit. Among them, the metal gasket 300 is a component that achieves "uniform force application". It is made of a metal material with both high conductivity (to ensure low loss transmission of electrical signals) and high elastic modulus (to ensure small deformation and uniform pressure transmission), such as beryllium copper alloy. The lower surface of the metal gasket 300 is finely ground and has extremely high flatness to ensure full-area contact with the positive electrode surface of the piezoelectric ceramic element 200. The diameter or size of the metal gasket 300 is configured to be slightly larger than or completely cover the effective vibration area of ​​the positive electrode surface of the piezoelectric ceramic element 200; thus, when the concentrated force applied by the preload bolt 600 acts on the metal gasket 300, the highly rigid metal gasket 300 can diffuse this concentrated force and convert it into a uniform interfacial pressure distributed across its entire lower surface, thereby effectively providing a rigid and uniform mechanical boundary condition for the piezoelectric ceramic element.

[0036] The ultrasonic transducer connection method of this application specifically includes the following steps: Step 1, Interface Preparation: Clean the smooth bottom surface inside the metal casing 100 and the negative electrode surface of the piezoelectric ceramic element 200 with anhydrous ethanol or other cleaning agents to ensure that the two contact surfaces are free of oil, dust or other impurities, so as to create conditions for good contact. Step 2, component positioning: precisely place the piezoelectric ceramic component 200 with its negative electrode facing down on the smooth bottom surface inside the metal casing 100. Step 3: Install the connecting components. First, place the metal washer 300 with its machined lower surface facing down on the positive electrode surface of the piezoelectric ceramic element 200, ensuring complete coverage of the effective area. Then, fit the insulating bushing 400 onto the screw of the pre-tightening bolt 600. Next, pass the screw of the pre-tightening bolt 600 with the insulating bushing 400 through the through hole in the center of the metal washer 300 and the through hole in the bolt washer 500 in sequence. Step 4: Apply and calibrate the preload by screwing the end of the preload bolt 600 into the threaded hole of the protrusion 120 on the metal housing. Tighten the preload bolt 600 using a calibrated torque wrench until the preset torque value is reached, thereby generating the required axial preload. In step four above, the design principle of the preload is as follows: the preload has a design range. Its minimum value must be sufficient to overcome the microscopic unevenness of the contact surface, completely eliminate the microscopic gap between the negative electrode surface of the piezoelectric ceramic element 200 and the bottom surface of the metal shell 100, and realize the effective transfer of vibration energy; its maximum value must ensure that the compressive stress borne by the piezoelectric ceramic element 200 is much lower than the compressive strength of its material, leaving sufficient safety margin to prevent the element from being damaged due to excessive stress during long-term vibration. Step 5, Electrical connection: Connect the positive wire of the excitation circuit to the edge of the metal pad 300 by soldering, and connect the negative wire of the circuit to the grounding terminal of the metal casing 100. Thus, the current path is: positive electrode wire → metal pad 300 → positive electrode surface of piezoelectric ceramic element 200 → piezoelectric ceramic body → negative electrode surface of piezoelectric ceramic element 200 → metal shell 100 → negative electrode wire.

[0037] Example 1: The following embodiment uses a low-frequency ultrasound therapy head suitable for deep tissue treatment as an example to specifically illustrate the implementation of the present invention. This probe is designed with a center frequency of 1.0 MHz, a bandwidth ≥60%, and an effective depth of 3–5 cm. It is suitable for physiotherapy of deep tissues such as the lumbar region and knee joints, and mainly includes, from bottom to top: The metal casing 100 is made of medical-grade stainless steel or aluminum alloy. Its inner bottom surface is a high-flatness precision-machined smooth surface with a flatness requirement of ≤ 5μm (compliant with ISO 1101 standard) and a surface roughness Ra ≤ 0.4μm. This surface also serves as the acoustic radiation backing and electrical negative electrode. The piezoelectric ceramic element 200 is made of PZT-4 type piezoelectric ceramic and is made into a circular monolithic structure with a diameter of 25 mm and a thickness of 1.5 mm (frequency and thickness are inversely proportional: for PZT-4, the half-wave thickness resonant frequency ≈ 1 MHz corresponds to a thickness of 1.5 mm). Its upper and lower surfaces are covered with silver electrode coatings with a thickness of 5–10 μm and a sheet resistance ≤ 10 mΩ / sq, which serve as the positive and negative electrodes, respectively. The connection assembly includes the following components: The metal gasket 300 is made of beryllium copper alloy (such as C17200), with an elastic modulus ≥120GPa and conductivity ≥18MS / m. The gasket diameter is slightly larger than the positive electrode surface of the piezoelectric ceramic element, with a thickness of 0.5 mm. The lower surface is finely ground to a flatness ≤3μm to ensure uniform pressure transmission and avoid stress concentration. The insulating bushing 400, made of polyimide (PI) or polyether ether ketone (PEEK), is fitted onto the pre-tightening bolt, located inside and above the through hole of the force equalizing washer, for electrical isolation, with a dielectric strength ≥15kV / mm; Bolt washers 500, standard flat washers, made of stainless steel, used to distribute pressure on bolt heads or nuts; The preload bolt 600 is made of high-strength stainless steel (such as A2-70) with a diameter of M4 to accommodate larger ceramic disc areas and preload requirements. The preload setting range is 0.5kN–2.0kN, and the corresponding torque control range is 2.0–6.0 N·m (calculated based on the thread friction coefficient of 0.12–0.15). The assembly process in this embodiment is as follows: Step 1: Clean the smooth inner bottom surface of the metal casing 100 and the negative electrode surface of the piezoelectric ceramic element 200 with anhydrous ethanol to ensure that there is no oil or dust. Step 2, component positioning: Place the piezoelectric ceramic component 200 with the negative electrode facing down precisely in the positioning groove on the inner bottom surface of the metal casing 100, with a positional deviation ≤ 0.1 mm; Step 3: Install the connecting assembly. Sequentially fit the metal gasket 300, insulating bushing 400, and bolt washer 500 onto the pre-tightening bolt 600. Pass the connecting assembly through the pre-set threaded through hole of the protrusion 120 of the housing base 110, and make the lower surface of the metal gasket 300 completely fit with the positive electrode surface of the piezoelectric element. Step 4: Apply and calibrate the preload: The minimum preload must be sufficient to eliminate microscopic gaps at the contact interface and achieve effective sound energy transfer; the required interfacial pressure... It can be calculated as:

[0038] in The equivalent elastic modulus of the contact materials (piezoelectric ceramics, metal gaskets, and housing). The overall surface roughness is 1-2 μm. The characteristic contact dimension (in this example, the diameter of the piezoelectric ceramic element is 25 mm). Calculations show that the minimum pressure required to achieve good coupling is 1–3 MPa; For a ceramic sheet with a diameter of 25 mm (area of ​​490.9 mm²), the minimum required total preload is... The resistance is 0.5kN–1.5kN; The maximum preload must ensure that the average compressive stress borne by the piezoelectric ceramic element is much lower than its compressive strength, and the stress concentration effect should be considered (the stress concentration factor is taken as 2-4, with 3 as an example). The typical compressive strength of PZT-4 is ≥600MPa, and the allowable compressive stress is taken as 1 / 10 of the compressive strength (i.e. 60MPa). After taking stress concentration factor into account, the actual allowable compressive stress is 20MPa. For a ceramic sheet with an area of ​​490.9 mm², the theoretical maximum allowable preload is 9.8 kN; To ensure sufficient safety margin, avoid edge stress concentration, and ensure reliability under long-term vibration, the maximum preload is limited to 2.0 kN (corresponding to an average compressive stress of 4.1 MPa). This value is far below the bearing capacity limit of ceramics and meets the interface tightness requirements.

[0039] In actual operation, use a precision torque wrench to tighten the preload bolt 600 to the set value of 3.5 N·m (generating a preload force of 1.2 kN, which is in the middle of the design range). When the resonant frequency of the piezoelectric element stabilizes at 1.00 ± 0.02 MHz and the impedance curve is smooth without stray peaks, it indicates that the coupling interface has reached the optimal tight state and the ceramic element is undamaged.

[0040] Step 5, electrical connection: The positive wire is welded to the edge of the rigid conductive force equalizing pad, and the negative wire is connected to the grounding terminal of the metal casing.

[0041] Additionally, see Figures 3 to 5 The acoustic performance of this application is verified as follows: As attached Figure 3 , Figure 4 and Figure 5 As shown, the radiated sound field of cylindrical and annular piezoelectric ceramic elements at 1MHz was simulated using finite element software with two connection methods: glued and bolted. The results shown are all radiated sound power density in the sound field analysis area below the therapy head. like Figure 3 and Figure 4 In the middle, the more concentrated and brighter the red pixel blocks are on the same horizontal plane, the higher the sound power density and the more concentrated the sound energy. And such Figure 5 As shown in the diagram, the more dispersed the distribution of red pixels, the more uniform the sound energy.

[0042] Therefore, by Figure 3 , Figure 4 The comparison shows that, under the same glued connection conditions, both cylindrical and annular piezoelectric ceramic elements have obvious focal points along the main acoustic axis of the radiated sound field. The sound power density at the focal point is significantly different from that at other points in the same plane, indicating poor uniformity. However, there is no significant difference in uniformity between the two, suggesting that the shape of the piezoelectric ceramic element is not the main factor affecting the uniformity of the sound field. Depend on Figure 4 , Figure 5 The comparison shows that, under the premise of the same piezoelectric ceramic element shape, when using the bolt connection method described in this application, the sound power density at the focal position of the 1MHz radiated sound field is less different from that at other points in the same plane, and the uniformity is significantly better than that of the radiated sound field when using glue connection.

[0043] In summary, this application, through uniform axial preload, forces the piezoelectric ceramic element 200 and the metal housing 100 into direct contact without an intermediate viscoelastic adhesive layer, eliminating the risk of connection failure and electroacoustic performance degradation caused by adhesive layer aging, creep, and fatigue, thus fundamentally improving connection reliability and equipment lifespan. Furthermore, the metal gasket 300 uniformizes the concentrated force of the bolts, and combined with the bottom surface of the housing, ensures that the constraint conditions on the entire back of the piezoelectric ceramic element 200 are spatially highly consistent. When the piezoelectric ceramic element 200 is excited by an electrical signal and vibrates in the thickness direction, its vibration energy can be synchronously and in phase transmitted to the entire radiating surface of the metal housing 100. This excited ultrasonic wavefront has extremely high phase consistency; furthermore, as... Figure 5 As shown, the bolted structure of this application significantly improves the uniformity of the radiated sound field (taking 1MHz as an example) due to the uniform and stable coupling, and effectively suppresses the phenomenon of local focal energy concentration. This results in a smooth and uniform sound energy distribution in the treatment area, fundamentally avoiding the burning or stinging sensation in the patient's subcutaneous tissue caused by excessive local energy, and greatly improving the safety and comfort of the treatment.

[0044] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0045] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An ultrasonic transducer connection structure, characterized in that, include: The metal casing (100) has a smooth bottom surface perpendicular to the axial direction on its inner side; A piezoelectric ceramic element (200) has a positive electrode surface, a negative electrode surface, and an electrode coating connected to the positive and negative electrode surfaces, wherein the negative electrode surface is disposed facing the smooth bottom surface of the metal housing (100); A connecting assembly configured to apply a spatially uniform axial preload to the positive electrode surface of the piezoelectric ceramic element (200) and force the negative electrode surface of the piezoelectric ceramic element (200) to form direct contact with the smooth bottom surface of the metal casing (100) through the preload.

2. The ultrasonic transducer connection structure according to claim 1, characterized in that, The connection component includes: A metal gasket (300) has its lower surface in direct contact with the positive electrode surface of the piezoelectric ceramic element (200); Preload bolt (600), and insulating bushing (400) sleeved on the preload bolt (600); The preload bolt (600) passes through the metal washer (300) and the insulating bushing (400) in sequence, and is threaded to the metal housing (100) to generate the axial preload force by tightening the preload bolt (600); the insulating bushing (400) is used to electrically isolate the preload bolt (600) from the metal washer (300) and the piezoelectric ceramic element (200).

3. The ultrasonic transducer connection structure according to claim 2, characterized in that, The metal casing (100) includes a casing base (110) and a protrusion (120) extending axially from the inside of the casing base (110), the end of the preload bolt (600) being threaded to the protrusion (120).

4. The ultrasonic transducer connection structure according to claim 2, characterized in that, The contact area between the lower surface of the metal pad (300) and the piezoelectric ceramic element (200) is configured to cover the active area of ​​the positive electrode surface of the piezoelectric ceramic element (200).

5. The ultrasonic transducer connection structure according to claim 1, characterized in that, The magnitude of the axial preload is configured such that the minimum value is sufficient to eliminate the gap between the negative electrode surface of the piezoelectric ceramic element (200) and the smooth bottom surface of the metal housing (100), and the maximum value is less than the compressive strength of the piezoelectric ceramic element (200) to maintain a long-term stable direct contact state under the rated operating conditions of the equipment.

6. The ultrasonic transducer connection structure according to claim 5, characterized in that, The minimum value of the axial preload force satisfies the following requirements: eliminating gaps at the contact interface and achieving effective sound energy transfer, the required interface pressure. for: in, The equivalent elastic modulus of the contact material; For overall surface roughness; This refers to the characteristic contact dimension.

7. A method for connecting an ultrasonic transducer, characterized in that, The method, employing the ultrasonic transducer connection structure as described in any one of claims 1-6, comprises: The negative electrode surface of the piezoelectric ceramic element (200) is placed facing the smooth bottom surface of the metal casing (100); Install the connection components; By operating the connecting assembly, a spatially uniform axial preload is applied to the positive electrode surface of the piezoelectric ceramic element (200), forcing the negative electrode surface of the piezoelectric ceramic element (200) to form direct contact with the smooth bottom surface of the metal casing (100).

8. The ultrasonic transducer connection method according to claim 7, characterized in that, The connection assembly includes a metal gasket (300), a preload bolt (600), and an insulating bushing (400). The process of installing the connecting assembly is as follows: the metal gasket (300) is placed on the positive electrode surface of the piezoelectric ceramic element (200), and the pre-tightening bolt (600) passes through the metal gasket (300) and the insulating bushing (400) sleeved on it in sequence, and then is threadedly connected to the metal shell (100). The process of applying axial preload is as follows: tighten the preload bolt (600) to the set torque to generate the axial preload.

9. The ultrasonic transducer connection method according to claim 8, characterized in that, The set torque is configured such that the resulting axial preload is between 0.5 kN and 2.0 kN.

10. An ultrasonic physiotherapy device, characterized in that, Includes the ultrasonic transducer connection structure as described in any one of claims 1-6.

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