An array-type micro ball valve and a piezoelectric micro pump

Abstract

This invention discloses an array-type microball valve and a piezoelectric micropump, relating to the fields of microelectromechanical systems and fluid machinery. The microball valve includes a valve chamber plate, a limiting plate, and multiple micron-sized rigid microball valve cores. The valve chamber plate has stepped, continuously abrupt, or gradually changing valve chamber holes arranged in an array. The microball valve cores are movably disposed within the valve chamber holes. The limiting plate is stacked and fixed to the valve chamber plate, and a cantilever beam structure elastic pressure rod is provided on it corresponding to each valve chamber hole, with the elastic pressure rod abutting against the microball valve core. When the valve is closed and subjected to reverse pressure, the elastic pressure rod actively presses the microball valve core against the air inlet to form a line contact hard seal. When the valve is open, under forward pressure and the fluid thrust is greater than the pressure rod stiffness force, the microballs lift the pressure rod to conduct the flow path. This invention achieves microsecond-level rapid response under high-frequency drive above 20kHz and physical cutoff under high reverse back pressure. The array design balances high flow rate and miniaturization, and the use of all-inorganic materials and glue-free encapsulation significantly improves fatigue life and yield.

Description

Technical Field

[0001] This invention relates to the fields of microelectromechanical systems and piezoelectric driven fluid machinery, and more specifically, to an array-type microball valve for a piezoelectric micro pump that can be adapted to high-frequency drive, and a piezoelectric micro pump including the array-type microball valve. Background Technology

[0002] A piezoelectric micro-pump is a miniature fluid machine that utilizes the inverse piezoelectric effect of piezoelectric ceramics to transport gas. Its basic working principle is as follows: under the excitation of an alternating electric field, the piezoelectric oscillator undergoes periodic high-frequency bending deformation, causing periodic expansion and compression of the closed pump chamber volume. Combined with the rectifying effect of a one-way valve, this achieves unidirectional gas intake and exhaust. Compared to traditional electromagnetically driven pumps, piezoelectric micro-pumps have significant advantages such as small size, low power consumption, and no electromagnetic interference.

[0003] To meet the stringent requirements of physical silence in modern medical equipment, portable instruments, and high-end electronic devices, the driving frequency of piezoelectric micropumps typically needs to be pushed to the ultrasonic frequency band above 20kHz, far exceeding the upper limit of human hearing. However, under high-frequency driving above 20kHz, the period of a single vibration of the piezoelectric oscillator is extremely short, usually not exceeding 50 microseconds, and the amplitude of a single vibration is tiny, only 2μm to 8μm. This results in extremely limited changes in pump chamber volume and transient gas driving force, typically at the millinewton level. This places extremely high demands on the high-frequency responsiveness, i.e., the response speed, and the pressure-holding and sealing capabilities of the one-way valve, the core component of the piezoelectric micropump.

[0004] Currently, the existing micro check valves for piezoelectric micro air pumps mainly fall into the following technical categories, but all of them have insurmountable defects.

[0005] I. Diaphragm Valves Made of Polymer Materials Existing technologies, such as Chinese patents CN118327943A (a piezoelectric micropump) and CN114992098A (a resonant excitation piezoelectric pump), disclose diaphragm-type check valves that use polymer films, such as polyurethane, PET, and polyimide, as valve plates, in conjunction with a rigid substrate with through holes. Figure 1As shown, this type of one-way valve typically includes a spacer 31, a first plate 32, a second plate 33, and a valve 34. The first plate 32 and the second plate 33 are respectively disposed on the upper and lower sides of the spacer 31, and the first plate 32 and the second plate 33 are perpendicularly inserted through the first hole 35 corresponding to the opening position. The valve 34 is disposed between the second plate 33 and the spacer 31, and the second plate 33 and the valve 34 are perpendicularly inserted through the second hole 36 corresponding to the opening position, with the second hole 36 offset from the first hole 35. The one-way valve vibrates up and down at the same frequency under the change of air pressure on both sides: when the valve 34 is in contact with the first plate 32, the pressure inside the air passage is greater than that inside the pump chamber, the valve is closed, and the air pump is in a stopped pumping state. However, because the valve 34 is made of polymer material, in the area of ​​the first hole 35 of the first plate 32, the polymer material valve 34 will undergo elastic deformation after being subjected to airflow pressure 38, and continue to deform towards the depth of the hole 35, forming a pressure loss area 37, which seriously reduces the valve's pressure holding capacity.

[0006] Furthermore, the connection method between the membrane and the rigid substrate also has limitations: bonding reduces fatigue life, and flowing adhesive can easily clog valve channels; the high temperature of laser welding can cause ablation damage to the membrane, and the membrane and welding point must maintain a large distance, which greatly reduces the input and output efficiency of the microvalve. At the same time, in order to fix the polymer resin membrane and the metal sheet, a third perforated metal sheet is required to clamp the polymer resin membrane in the middle, and a fourth metal frame structure is also required between the two metal sheets and the polymer resin membrane to provide deformation space. The laser welding process between the four layers is complex and has poor reliability.

[0007] Therefore, the defects of this type of valve are as follows: 1. Poor pressure holding capacity: When reverse pressure is generated in the pump chamber, i.e., when the valve needs to close to maintain pressure, the flexible polymer film will elastically deform into the depth of the pores of the rigid substrate under the action of airflow pressure, creating a so-called pressure loss depression zone, causing gas backflow, which severely limits the high-pressure output capacity of the air pump. Typically, the maximum back pressure it can withstand is only 20kPa to 40kPa. 2. High-frequency response hysteresis: Polymer materials have inherent viscoelastic hysteresis characteristics. Under high-frequency alternating loads above 20kHz, the mechanical response of the film lags significantly behind the drive signal, causing the valve to fail to close completely and the volumetric efficiency to drop sharply. 3. Short fatigue life and difficult encapsulation: Polymer films are prone to fatigue tearing under high-frequency reciprocating deformation; at the same time, the assembly of the film and the rigid substrate is extremely difficult. If glue is used for bonding, capillary action can easily cause glue overflow to block the microchannels; if laser welding is used, the high temperature can easily cause the polymer film to ablate or melt and deform, forcing the film to maintain a large distance from the welding point, thus wasting the effective vibration area and reducing the energy conversion efficiency.

[0008] II. Traditional macroscopic ball valves Existing technology, Chinese patent CN108468636B, discloses a piezoelectrically driven pump utilizing a lightweight ball valve. This piezoelectric pump uses polystyrene balls as one-way valve cores, with the ball diameter ranging from 1mm to 5mm. The ball is constrained within a flow channel composed of three orifices, and moves up and down by fluid drag, its own buoyancy, and gravity to achieve the switching function. Figure 2 As shown, this type of ball valve includes an inlet 11, a valve chamber 12, a valve core ball 13, an outlet 14, and a spring pressure plate 15. The valve core ball 13 is relatively large in size and mass. The airflow 10 generated by the deformation of the piezoelectric vibrator is insufficient to push the valve core ball 13. Furthermore, since mass is inversely proportional to the movement frequency, the back-and-forth movement frequency of the larger mass valve core ball 13 is low. The large mass leads to high pressure transmission lag. At the same time, because of its large size, the length of the spring plate 15 controlling the movement of the valve core ball is also increased, and the start-up time of the spring pressure plate 15 is longer. The defects of this type of valve are: 1. Severe lag, unable to adapt to high-frequency drive; mass is inversely proportional to the movement frequency, and the mass and motion inertia of a 1mm to 5mm ball in micro-fluids are too large. Under the extremely small fluid driving force of the piezoelectric pump at the millinewton level, the opening and closing time of the large mass ball valve is too long, unable to keep up with the driving frequency above 20kHz, which can easily lead to pump-valve phase misalignment, or even cause the air pump to stop working completely. 2. Lack of an active reset mechanism: The ball valve in this technical solution lacks any active elastic reset element such as a spring or elastic rod. The opening and closing of the valve relies entirely on fluid dynamics, making its shut-off tightness and response sensitivity completely uncontrollable in high-frequency microflow fields. 3. The conflict between flow rate and pressure holding cannot be reconciled: If the size of a single ball valve is forcibly reduced to improve response speed, the overall airflow of the air pump will decrease significantly, failing to meet the needs of high-flow-rate applications.

[0009] III. Valveless Fluid Control Route Existing technology, Chinese patent CN117627900B, discloses a miniature piezoelectric pump with multiple inlet Tesla valve channels. This scheme employs a fractal geometry Tesla valveless channel at the inlet for fluid rectification, theoretically avoiding the high-frequency response problem of mechanical moving parts. However, the valveless piezoelectric pump relies on the difference in fluid resistance between the forward and reverse directions, rather than an absolute physical cutoff. During the piezoelectric oscillator's exhaust and pressurization stroke, a significant proportion of high-pressure fluid inevitably leaks backward through the inlet channel, resulting in low volumetric efficiency of the pump chamber and an inability to generate sufficient macroscopic output pressure. Therefore, it is unsuitable for applications requiring strict high back pressure holding.

[0010] IV. Integrated metal valve plate with valve-oscillator Existing technology, Chinese patent CN101328879B, discloses a valve-oscillator integrated piezoelectric pump that uses a punching process to cut slits in a metal sheet to form a moving valve disc and a connecting hinge, utilizing the elastic restoring force of the metal material itself to achieve valve opening and closing. However, this solution faces an inherent paradox in materials mechanics: if the connecting hinge is wide enough to improve pressure resistance and pressure holding capacity, the equivalent stiffness of the metal valve disc is too large, making it unable to open quickly under the weak driving force of the piezoelectric oscillator; if the hinge is cut extremely narrow to obtain the flexibility required for high-frequency response, stress concentration and metal fatigue fracture can easily occur at the root of the hinge under millions of high-frequency reciprocating bending stresses. This single-layer metal valve disc, relying on its own bending, cannot simultaneously achieve both the responsiveness of high-frequency opening and closing and the structural integrity of long-term operation.

[0011] In summary, existing micro-check valves, whether miniaturized polymer diaphragm valves that sacrifice rigidity and pressure holding capacity, traditional ball valves that possess rigidity but suffer from excessive mass and slow response, or valveless flow channels and integrated metal valve plates, cannot simultaneously meet the comprehensive requirements of piezoelectric micro-pumps in four dimensions: ultrasonic high-frequency drive, high back pressure holding capacity, long fatigue life, and large flow output. Therefore, there is an urgent need in this field for a novel micro-check valve structure to overcome the aforementioned technical bottlenecks. Summary of the Invention

[0012] The problem this invention aims to solve is that existing one-way valves for piezoelectric micro-pumps cannot simultaneously achieve microsecond-level rapid response under ultra-high frequency drive above 20kHz, absolute physical hard seal pressure holding under high back pressure, large flow output, and high fatigue life under long-term operation. Furthermore, existing multilayer micro-valve are prone to capillary overflow of adhesive clogging micropores during packaging manufacturing, or thermal damage to the structure caused by high laser temperatures, making it difficult to achieve reliable packaging with high yield and high cleanliness. Specifically, polymer diaphragm valves suffer from high-frequency response hysteresis, poor pressure holding capacity, susceptibility to fatigue tearing, and packaging difficulties; traditional macroscopic ball valves suffer from high-frequency inertial hysteresis due to excessive mass, cannot follow the movement, and lack an active reset mechanism; valveless flow channels suffer from reverse leakage and low output pressure; and integrated metal valve plates suffer from stress concentration at the hinge, making it difficult to balance flexibility and fatigue strength.

[0013] To address the above problems, this invention provides an array-type micro-ball valve for a piezoelectric micro-pump, comprising: A valve cavity plate has multiple valve cavity holes arranged in an array. Each valve cavity hole is a stepped hole, a hole with abrupt change in diameter, or a hole with a gradual change in diameter. It includes an air inlet, a valve core cavity, and an air outlet that are coaxially connected. The diameter of the air inlet is smaller than the diameter of the valve core cavity. Multiple microball valve cores, each of which is independently and movably disposed in a corresponding valve core cavity, wherein the microball valve core is a rigid ball; A limiting plate is stacked and fixedly disposed with the valve cavity plate; an elastic pressure rod is provided on the limiting plate at the position corresponding to each valve cavity hole, the elastic pressure rod is a cantilever beam structure, and its free end abuts against the microball valve core; In the non-working state or the reverse pressure state when the valve is closed, the elastic pressure rod presses the microball valve core against the air inlet to form a line contact hard seal; in the forward pressure state when the valve is open, when the fluid pressure difference is greater than the stiffness force of the elastic pressure rod, the microball valve core pushes up the elastic pressure rod to make it elastically deformed, thereby opening the air inlet.

[0014] Preferably, the microball valve core is a ceramic or metal microsphere with a diameter between 0.05 mm and 1 mm. More preferably, it is between 0.05 mm and 0.5 mm, further clarifying the optimal solution for mass and stiffness. The ceramic or metal material ensures extremely high compressive strength and wear resistance, preventing denting or deformation under reverse high pressure. This extremely small size range allows the inertial mass of a single microsphere to approach the control limit of a microelectromechanical system, ensuring not only microsecond-level ultra-fast opening and closing at ultra-high frequencies above 20 kHz, completely overcoming the inertial hysteresis of macroscopic ball valves, but also guaranteeing the operability and mass production feasibility of subsequent ball implantation processes.

[0015] Preferably, the valve cavity holes on the valve cavity plate are arranged in a rectangular array; multiple connecting plates are spaced apart on the limiting plate, and the elastic pressure rod is disposed on the connecting plate and extends to both sides, corresponding to the positions of the valve cavity holes on adjacent sides. This maximizes the spatial arrangement density of the micro-ball valves within a limited two-dimensional plane, multiplying the total flow cross-sectional area without increasing the macroscopic volume of the pump body. Simultaneously, the rectangular symmetrical arrangement greatly simplifies matrix programming positioning during microfabrication and orientation recognition during assembly, reducing production costs. Each micro-ball valve core can open and close independently and asynchronously according to real-time pressure changes in the local microflow field, effectively compensating for uneven pressure distribution within the pump cavity and greatly improving the valve assembly's tolerance and response sensitivity to complex flow fields.

[0016] Preferably, the projected geometric space of the valve chamber plate is rectangular or circular, with a length not exceeding 10 mm and a width not exceeding 8 mm, or a diameter not exceeding 10 mm; the number of valve chamber holes is at least two rows and two columns or two rows and two columns. This strictly limits the maximum macroscopic size of the valve chamber plate and the minimum array density of the valve chamber holes. This allows the microball valve assembly of the present invention to be perfectly embedded in the heat dissipation modules of extremely small portable medical wearable devices or highly integrated electronic chips. Through the parallel operation of dozens or even hundreds of microball valves, utilizing the frequency advantage of microscopic ultra-fast opening and closing combined with the quantitative advantage of arrayed multi-channels, a stable and continuous high-flow-rate gas output is achieved macroscopically, achieving an excellent balance between extreme miniaturization and high-flow-rate ventilation.

[0017] Preferably, the elastic pressure bar is made of metal, with a width of 0.02mm to 0.8mm and a cantilever length of 0.03mm to 1.5mm. More preferably, the width is 0.02mm to 0.3mm and the cantilever length is 0.03mm to 0.4mm. This precisely defines the width-to-length ratio of the metal elastic pressure bar. This stringent dimensional combination is crucial for balancing the fluid thrust opening and stiffness force reset. These dimensional parameters ensure that the elastic deformation of the cantilever beam is precisely within the linear elastic region of the material, guaranteeing instantaneous opening under millinewton-level fluid positive pressure while avoiding stress concentration. Simultaneously, the high elastic modulus and fatigue resistance of the metal material ensure that the working alternating stress is far below the material's fatigue limit, physically guaranteeing an ultra-long fatigue life under hundreds of millions of high-frequency bends, further solving the defect of easy breakage at the hinge of existing integrated valve-oscillator metal valve plates.

[0018] Preferably, the valve chamber plate and the limiting plate are provided with a first riveting hole and a second riveting hole that are aligned in position. The two plates are fixedly connected by riveting or welding through a solder ball riveting body inserted into the riveting hole; or they are made from a single plate using a semi-etching process.

[0019] Furthermore, each pair of adjacent valve cavity holes forms a group, and a first riveting hole is provided at the middle position of each group of valve cavity holes; the connecting plate is provided with a second riveting hole corresponding to the position of the first riveting hole; the valve cavity plate and the limiting plate are fixedly connected by solder ball riveting bodies implanted in the first riveting hole and the second riveting hole. A packaging process using solder ball riveting or reflow soldering is employed. This packaging process innovatively introduces advanced semiconductor packaging technology into the field of microfluidics, without any organic liquid adhesives throughout the process, completely eliminating the fatal risk of capillary adhesive overflow clogging micron-level valve holes from a physical principle perspective; at the same time, the reflow soldering temperature is controllable and relatively low, supplemented by inert gas protection, far lower than laser soldering, effectively avoiding thermal stress warping deformation and thermal damage of micro-fine structures, achieving high cleanliness, high yield, and high consistency batch packaging of micro-components.

[0020] Preferably, the main structures of the valve chamber plate and the limiting plate are integrally formed from metal or ceramic materials through an etching process. The microball valve core is integrally formed from metal or ceramic materials. The etching process can achieve extremely high micron-level two-dimensional and three-dimensional machining accuracy, avoiding burrs and micro-cracks produced by traditional machining, ensuring extremely high surface finish of the stepped hole inner wall and the microball valve core sealing surface, further improving the pressure-holding effect of the line contact hard seal (i.e., Hertzian contact) between the rigid spherical surface and the edge of the air inlet, and achieving absolute physical cutoff when the fluid flows in reverse.

[0021] Preferably, a piezoelectric micro-pump includes: The pump body has a pump cavity formed inside it, and the pump body has an air inlet and an air outlet communicating with the pump cavity. A piezoelectric vibrator, which is sealed to the pump body and forms at least a portion of the wall of the pump cavity, is used to generate reciprocating bending deformation under the drive of an alternating electrical signal to change the volume of the pump cavity; It also includes at least two array-type micro-ball valves as described in any of the above, namely a first array-type micro-ball valve and a second array-type micro-ball valve. One of the array-type micro-ball valves is installed at the air inlet with its unidirectional flow direction pointing towards the inside of the pump chamber, and the other array-type micro-ball valve is installed at the exhaust port with its unidirectional flow direction pointing away from the pump chamber and towards the outside. By configuring two array-type micro-ball valves in opposite directions at the air inlet and exhaust port of the pump body, the high-frequency micro-amplitude oscillations (≥20kHz, 2μm~8μm) generated by the piezoelectric vibrator are efficiently converted into a macroscopically continuous, unidirectional directional gas flow. Since both array-type micro-ball valves have extremely fast high-frequency response capabilities and absolute physical cutoff and pressure holding capabilities, the entire system completely eliminates the persistent problems of airflow back leakage and volumetric efficiency decay in traditional piezoelectric pumps under high-frequency operation. Ultimately, this allows the entire piezoelectric micro-pump product to maintain excellent high flow rate and high back pressure output even under the stringent conditions of physical silence that completely exceeds the upper limit of human hearing. Specifically, the two micro-ball valves are installed in opposite directions, one for inlet and one for outlet. This allows the inlet valve to open and the outlet valve to close when the piezoelectric vibrator bends upward (i.e., the pump chamber expands), drawing gas into the pump chamber. Conversely, when the piezoelectric vibrator bends downward (i.e., the pump chamber compresses), the inlet valve closes and the outlet valve opens, compressing the gas and pumping it out from the outlet. This achieves continuous unidirectional gas delivery from the inlet to the outlet, forming a complete unidirectional rectified flow circuit. Both micro-ball valves feature the aforementioned active reset structure combining a rigid ball with an elastic pressure rod. Regardless of whether the pump chamber is in the intake or exhaust phase, the closed valves can withstand reverse high pressure from the pump chamber or external sources, achieving absolute physical cutoff and effectively preventing gas backflow. This significantly improves the pump's volumetric efficiency and output pressure, achieving reliable bidirectional shut-off. Both micro-ball valves have microsecond-level opening and closing response speeds, perfectly matching high-frequency drives. They can maintain high phase synchronization with piezoelectric vibrators driven at ultra-high frequencies above 20kHz, ensuring the pump maintains excellent output performance even under high-frequency conditions.

[0022] Preferably, the array-type micro-ball valve one and array-type micro-ball valve two are assembled with the air inlet and exhaust port of the pump body using an adhesive-free interference fit. The micro-ball valve assembly is also assembled with the pump body's air inlet and exhaust port using an adhesive-free small interference fit. This avoids the risk of secondary contamination from adhesives introduced during the final assembly of the entire unit, ensuring the absolute cleanliness of the microchannels inside the pump chamber. Furthermore, the small interference fit utilizes the structure's own elastic compressive force to achieve reliable gas sealing at the edges, simplifying the assembly process, improving the reliability of the finished air pump, and facilitating disassembly and repair.

[0023] Preferably, the operating frequency of the piezoelectric vibrator is configured to be no less than 20kHz, and the vibration amplitude of the piezoelectric vibrator is configured to be 1μm to 20μm, more preferably 2μm to 8μm. This limits the overall operating frequency of the piezoelectric micro-pump to the ultrasonic frequency band above 20kHz. This completely eliminates audible noise, achieving physical silence. The tiny amplitude of 2μm to 8μm, combined with the highly sensitive array micro-valve of this invention, enables the output of extremely smooth macroscopic airflow with extremely low power consumption. This achieves optimal energy utilization of the entire pump-valve system, significantly improving the overall efficiency and volumetric efficiency of the pump, perfectly meeting the active silent heat dissipation requirements of precision medical instruments, wearable devices, and high-end office equipment.

[0024] Compared with the prior art, the present invention achieves the following beneficial technical effects: This invention breaks through the bottleneck of ultra-high frequency response, achieving excellent follow-up response under ultra-high frequency drive above 20kHz, overcoming the defects of existing polymer membrane hysteresis and large inertia of large ball valves. This invention uses a miniature rigid ball with a diameter of only 0.05mm to 0.5mm as the valve core, reducing its mass by several orders of magnitude compared to macroscopic ball valves, resulting in extremely low motion inertia and significantly reducing the inertial mass of moving parts. Simultaneously, in conjunction with a metal cantilever beam structure elastic pressure rod with high-frequency elasticity, the micro-ball valve core can not only open rapidly under extremely weak fluid millinewton positive pressure, but also achieve rapid reset and closure by relying on the active stiffness force of the elastic pressure rod. The elastic pressure rod can rapidly deform elastically to open the valve when the forward fluid pressure difference exceeds its stiffness force; under reverse pressure, it actively and rapidly forces the micro-ball valve core back to the closed position using the unique rigid restoring force of metal. This synergistic effect of the micron-sized rigid ball combined with the active reset of the metal cantilever beam allows the valve core to open and close within microseconds, perfectly matching the ultra-high frequency drive requirements above 20kHz. It completely eliminates the inertial hysteresis of existing macroscopic ball valves and the viscoelastic hysteresis of polymer films, ensuring that the valve opening and closing and the deformation of the piezoelectric vibrator remain highly phase synchronized in the ultrasonic frequency band of 20kHz or even higher, thus guaranteeing the high volumetric efficiency of the air pump.

[0025] This invention achieves absolute physical shut-off under high back pressure, resulting in a qualitative leap in pressure holding capacity. It significantly improves the valve's pressure holding and shut-off sealing performance, overcoming the defect of existing polymer membranes that easily collapse and lose pressure. Unlike the flexible polymer films in existing technologies that are easily deformed under pressure, this invention uses a rigid sphere with extremely high volumetric elastic modulus as the valve core. It will not undergo any collapse or deformation under reverse high pressure. Simultaneously, in conjunction with the stepped-hole structure at the air inlet end, a high-contact-stress line contact hard seal, i.e., Hertzian contact, is formed under the active pressure of the elastic pressure rod. Furthermore, in the reverse pressure holding state, there is not only reverse fluid pressure but also mechanical pressure applied by the elastic pressure rod. This sealing mechanism of a rigid sphere, active elastic compression, and stepped-hole hard support achieves a qualitative leap in the valve's reverse shut-off performance, completely avoiding the pressure loss and dead zone problem of diaphragm valves. It achieves absolute physical shut-off when the fluid flows in reverse, resulting in a leapfrog improvement in the ultimate back pressure output capacity of the piezoelectric micro-pump, meeting the stringent requirements of high back pressure holding scenarios.

[0026] This invention's array design perfectly resolves the physical contradiction between miniaturization and high flow rate, achieving a perfect balance between high flow rate and high response, and solving the problem of insufficient flow rate of a single microvalve. Miniaturizing individual valve cores to 0.05mm–0.5mm to accommodate high-frequency actuation inevitably leads to a sharp decrease in single-orifice ventilation and a significant reduction in flow area. This invention addresses this by creating multiple valve cavity orifices arranged in a rectangular array on a tiny valve cavity plate, forming a high-density micro-ball valve group. Through the parallel operation of dozens or even hundreds of micro-ball valves, the invention leverages the frequency advantage of extremely rapid microscopic opening and closing combined with the quantitative advantage of the arrayed multi-channel design, achieving stable and continuous high-flow-rate gas output on a macroscopic scale. Simultaneously, driven by a piezoelectric oscillator, each micro-ball valve core in the array can independently and asynchronously complete its opening and closing action based on real-time pressure changes in the local micro-flow field. The independent response of each micro-ball valve effectively compensates for uneven pressure distribution in the local micro-flow field within the pump cavity, greatly improving the overall valve group's tolerance and response sensitivity to complex flow fields. This spatially distributed parallel array coordination mechanism, while maintaining the extremely fast response of individual microvalves, macroscopically increases the flow area, perfectly reconciling the physical contradiction between large flow rate and high frequency response.

[0027] This invention completely eliminates polymer materials, achieving ultra-long fatigue life and high reliability. The core moving components—ceramic or metal microspheres, metal cantilever beam elastic pressure rods, etched valve cavity plates, and limiting plates—are all made of high-strength, fatigue-resistant inorganic or metallic materials, completely eliminating the easily aging and fatigue-tearable polymer films. It also solves the problem of stress concentration at the hinges and easy breakage during high-frequency bending in existing integrated metal valve plates. In particular, the elastic pressure rod of the cantilever beam structure, with its specific width-to-length ratio design, transforms the stress mode into uniform elastic bending deformation. The alternating stress during operation is far below the material's fatigue limit, effectively avoiding stress concentration. It can withstand hundreds of millions of high-frequency micro-bending without fatigue fracture, fundamentally ensuring the long-term operational reliability of the piezoelectric micro-pump under harsh conditions such as medical applications and high-performance chip cooling, significantly extending the valve's service life.

[0028] This invention overcomes the challenges of micro-valve packaging technology, achieving highly reliable sealing with no overflow and no thermal damage. It also overcomes and aligns with MEMS micro / nano manufacturing processes, enabling high-yield, glue-free packaging. The valve cavity plate and limiting plate are integrally formed using metal or ceramic etching processes, ensuring micron-level dimensional accuracy. During multilayer board assembly, solder ball riveting or reflow soldering packaging processes are employed, with solder ball rivets inserted through aligned riveting holes for secure connection. The entire process is free of organic adhesives, completely eliminating the risk of adhesive overflow clogging holes. Furthermore, the soldering temperature is controllable, preventing damage to the microstructure. This assembly method completely abandons traditional glue bonding, avoiding the problem of capillary adhesive overflow clogging micron-level valve holes, and also avoids the risk of microstructure thermal damage caused by laser welding ablation of the polymer film. The low and controllable process temperature significantly improves the yield rate of micro-valve assembly and the consistency of mass production. Meanwhile, the array-type micro ball valve is assembled with the pump body's air inlet and exhaust port using a small interference fit without adhesive, which further ensures the ultra-high cleanliness of the microchannel and achieves high yield and high cleanliness batch packaging of micro valves.

[0029] The stiffness of the elastic pressure bar in this invention, together with the diameter and mass of the microball valve core, constitutes a highly adjustable pressure threshold system. By precisely designing the width and cantilever length of the elastic pressure bar, the valve opening pressure threshold can be flexibly adjusted for different application scenarios, such as high flow rate and low pressure or low flow rate and high back pressure. Furthermore, in MEMS etching processes, the inherent machining errors cause minute random variations in the stiffness of each elastic pressure bar and the diameter of the microball valve core in the array. This error, considered a defect in traditional single-valve systems, unexpectedly becomes an advantage in the array structure of this invention: the opening time of each microball valve core exhibits a microsecond-level misalignment, forming a continuous opening pressure threshold band. This asynchronous misalignment effect effectively smooths the fluid pulse peak impact caused by the high-frequency oscillation of the piezoelectric vibrator, significantly suppresses high-frequency aerodynamic noise, and makes the output air pressure more stable. Attached Figure Description

[0030] Figure 1 A cross-sectional schematic diagram showing the working state of a polymer diaphragm valve in the prior art; Figure 2 This is a cross-sectional schematic diagram of the working state of a conventional ball valve in the prior art; Figure 3 This is a cross-sectional schematic diagram of the overall structure of the piezoelectric micro-pump provided in an embodiment of the present invention; Figure 4 The diagram below shows the working principle of the piezoelectric micro pump provided in the embodiment of the present invention, wherein (a) is a schematic diagram of the air intake process and (b) is a schematic diagram of the air exhaust process; Figure 5 This is a schematic diagram illustrating the internal structure and working principle of a single micro-ball valve provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the assembly structure and working state of the array-type micro ball valve provided in an embodiment of the present invention, wherein (a) is the valve closed state and (b) is the valve open state; Figure 7 This is a top view of the overall structure of the valve chamber plate provided in an embodiment of the present invention; Figure 8 for Figure 7 A partially enlarged schematic diagram of the hole distribution in the valve chamber plate; Figure 9 This is a top view of the overall structure of the limiting plate provided in an embodiment of the present invention; Figure 10 for Figure 9 A partially enlarged structural diagram of the middle limiting plate.

[0031] Explanation of reference numerals in the attached drawings: 1-Array type micro ball valve one; 2-Pump body; 201-Pump chamber; 202-Air inlet; 203-Exhaust port; 3-Piezoelectric vibrator; 301-Metal substrate; 302-Piezoelectric ceramic; 4-Array type micro ball valve two; 101-Valve chamber plate; 1011-First riveting hole; 1012-Valve chamber hole; 10121-Air inlet; 10122-Valve core chamber; 10123-Air outlet; 102-Limiting plate; 1021-Second riveting hole; 1022-Connecting plate; 1023-Elastic pressure rod; 103-Micro ball valve core; 104-Solder ball riveting body; 10-Air flow; 11-Air inlet; 12-Valve chamber; 13-Valve core ball; 14-Air outlet; 15-Spring pressure plate; 31-Spacer; 32-First plate; 33-Second plate; 34-Valve; 35-First orifice; 36-Second orifice; 37-Depressurization area; 38-Airflow pressure. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further explained and described below in conjunction with the accompanying drawings and embodiments.

[0033] Example 1: See Figures 5 to 10 As shown, this embodiment provides an array-type micro-ball valve specifically for ultra-high frequency piezoelectric micro-pumps, which is mainly composed of a valve chamber plate 101, a limiting plate 102, multiple micro-ball valve cores 103, and a solder ball riveting body 104 for connection.

[0034] Specifically, please refer to the following: Figure 7 and Figure 8 The valve cavity plate 101 serves as the main support structure of the valve, and it has multiple valve cavity holes 1012 arranged in a rectangular array. To meet the miniaturization requirements of MEMS and related devices, the overall macroscopic dimensions of the valve cavity plate 101 are strictly controlled: the total length is no more than 10 mm, and the total width is no more than 8 mm. Within this small area, at least two rows and two columns of valve cavity holes 1012 are evenly distributed; in this embodiment, it is preferably 8 rows × 12 columns, for a total of 96 valve cavity holes.

[0035] Furthermore, please combine Figure 5 and Figure 6 As shown, each valve cavity orifice 1012 is machined into a coaxially connected stepped orifice structure, sequentially including an air inlet 10121 (valve cavity inlet), a valve core cavity 10122, and an air outlet 10123 (valve cavity outlet) along the forward flow direction of the fluid. The diameter of the air inlet 10121 is strictly smaller than the diameter of the valve core cavity 10122, thus forming a hard physical step at their junction for the microsphere to rest on, constituting a hard-seal valve seat.

[0036] Multiple microball valve cores 103 are independently and movably disposed within a corresponding valve core cavity 10122. To completely overcome the inertial hysteresis of macroscopic ball valves under high-frequency actuation, the microball valve cores 103 in this embodiment are micron-sized rigid spheres with a diameter of only 0.05 mm to 0.5 mm. Preferably, the material is a high-temperature resistant ceramic material such as zirconium oxide, or a high-strength metal material such as titanium alloy. These materials not only make the microspheres extremely lightweight, enabling microsecond-level high-frequency servo response, but also have extremely high bulk modulus of elasticity and compressive strength, ensuring no deformation under reverse high pressure.

[0037] Please see Figure 9 and Figure 10As shown, the limiting plate 102 is stacked and fixedly disposed on the side of the valve chamber plate 101 with the air outlet 10123. Multiple connecting plates 1022 are evenly arranged at intervals along the length of the limiting plate 102. In this embodiment, there are six connecting plates. Multiple elastic pressure rods 1023 extend to both sides on these connecting plates 1022, and the positions of the elastic pressure rods 1023 correspond one-to-one with the respective valve chamber holes 1012 below.

[0038] The elastic compression bar 1023 is a metal cantilever beam structure with its width strictly controlled between 0.02mm and 0.3mm and its cantilever length controlled between 0.03mm and 0.4mm. This specific width-to-length ratio design ensures that the deformation of the metal cantilever beam lies precisely within the linear elastic region of the material. This provides excellent high-frequency elastic response while avoiding stress concentration, enabling it to withstand hundreds of millions of high-frequency micro-bending events without fatigue fracture.

[0039] Another key innovation of this embodiment lies in its adhesive-free micro / nano packaging process. The main structures of the valve chamber plate 101 and the limiting plate 102 are integrally formed from metal or ceramic materials through MEMS etching, ensuring micron-level processing precision and avoiding the impact of burrs and micro-cracks generated by traditional machining on sealing performance.

[0040] like Figure 8 and Figure 10 As shown, on the valve chamber plate 101, every two adjacent valve chamber holes 1012 form a group, and a first riveting hole 1011 is provided at the middle position of each group of valve chamber holes; the corresponding connecting plate 1022 of the limiting plate 102 is also provided with a second riveting hole 1021 for alignment. At the same time, edge riveting holes for alignment are also provided on the four edges of the valve chamber plate 101 and the limiting plate 102.

[0041] During assembly, the microball valve cores 103 are first precisely implanted into their respective valve core cavities 10122 using a fully automated ball-planting device. Then, the valve cavity plate 101 and the limiting plate 102 are aligned and stacked, and solder ball rivet bodies 104 are implanted into the aligned first riveting hole 1011 and second riveting hole 1021. Finally, under inert gas protection, a temperature-controlled reflow soldering or laser-guided point riveting process is used to melt and solidify the solder balls, thereby firmly bonding the two layers together. This process completely eliminates the fatal risk of traditional fluid adhesives overflowing and clogging micron-level valve orifices due to capillary action, and also avoids the problem of thermal damage to the microstructure caused by direct laser welding, achieving high-yield mass production of array-type microball valves.

[0042] Please see Figure 5 and Figure 6 As shown, after assembly, the free end of the elastic pressure rod 1023 abuts against the top of the micro ball valve core 103.

[0043] 1. Closed state: e.g. Figure 6 As shown in Figure a, in the non-working state or under reverse pressure (i.e., the air pressure on the outlet 10123 side is higher than that on the inlet 10121 side), the elastic pressure rod 1023, made of metal, utilizes its inherent stiffness and restoring force to actively and quickly press the normally closed micro-ball valve core 103 downward against the stepped end of the inlet 10121. The rigid spherical surface of the micro-ball valve core 103 and the hard edge of the inlet 10121 form a high-contact-stress line seal, i.e., Hertzian contact, achieving absolute physical cutoff when the fluid flows in reverse, and possessing extremely high pressure-holding capacity.

[0044] 2. On status: e.g. Figure 6 As shown in b, under positive pressure, that is, when the positive pressure of the fluid below the air inlet 10121 is greater than the pressure above, and when the thrust generated by the fluid pressure difference is greater than the stiffness force of the elastic rod 1023, the micro ball valve core 103 is instantly pushed upward, forcing the elastic rod 1023 to undergo a slight elastic bending deformation, the air inlet 10121 is opened, and the fluid achieves unidirectional flow.

[0045] When the positive pressure difference decreases to below the stiffness force of the elastic rod 1023, the elastic rod 1023, relying on its own elastic restoring force, actively pushes the micro-ball valve core 103 back to the end of the air inlet 10121, and the valve closes again.

[0046] The array-type micro-ball valve of the present invention achieves a synergistic effect of microscopic ultra-fast opening and closing and arrayed multi-channel by arranging 96 micro-ball valve cores in a high-density array. Driven by a piezoelectric oscillator, each micro-ball valve core 103 in the array can independently and asynchronously complete the opening and closing action according to the real-time pressure change of its local coordinate.

[0047] Specifically, in MEMS etching and assembly processes, there are inherently minute system tolerances in the cantilever dimensions and microsphere diameters. In traditional single-valve systems, such processing errors are considered defects. However, in the high-density array of this embodiment, these random, discrete tolerances unexpectedly transform into a series of continuous opening pressure threshold bands. Each microball valve exhibits asynchronous opening and closing actions with microsecond-level time differences, based on its local micro-pressure difference and its own physical threshold. This spatially distributed parallel working mechanism not only accumulates a significantly larger ventilation volume on a macroscopic scale but also effectively smooths high-frequency aerodynamic pulse peaks, greatly suppresses high-frequency aerodynamic noise, and results in extremely smooth and stable output air pressure.

[0048] Example 2: Based on the array-type micro-ball valve described in Example 1, this example provides a complete piezoelectric micro-pump assembly including an array-type micro-ball valve group. Please refer to... Figure 3 and Figure 4 As shown, the piezoelectric micro pump includes a pump body 2, a piezoelectric vibrator 3, and at least two arrayed micro ball valves.

[0049] The pump body 2 has an internally formed pump chamber 201 for containing gas. The pump body 2 has an air inlet 202 and an exhaust port 203 that communicate with the pump chamber 201. The pump body 2 can be made of metal or polymer material.

[0050] The piezoelectric vibrator 3 is composed of a metal substrate 301 and a piezoelectric ceramic 302 bonded together, and is sealed to the open end of the pump body 2, forming the deformable wall surface of the pump cavity 201. In this embodiment, the operating frequency of the piezoelectric vibrator 3 is configured to be no less than 20kHz, preferably in the 20kHz to 25kHz ultrasonic frequency band, to achieve physical silence, and its vibration amplitude is configured to be 2μm to 8μm. Under the drive of an alternating electrical signal, the piezoelectric vibrator generates high-frequency reciprocating bending deformation, thereby changing the volume of the pump cavity 201 at high frequency. However, the vibration amplitude can be adjusted within the range of 1μm to 20μm. In this embodiment, two array-type micro-ball valves as described in Embodiment 1 are provided, serving as the inlet valve, namely array-type micro-ball valve 4, and the outlet valve, namely array-type micro-ball valve 1.

[0051] Among them, the array-type micro ball valve 24 is installed at the air inlet 202 of the pump body 2, and its one-way conduction direction is pointing towards the inside of the pump chamber 201, allowing only external gas to be drawn in; the array-type micro ball valve 1 is installed at the exhaust port 203, and its one-way conduction direction is away from the pump chamber 201 and points outward, allowing only the gas inside the chamber to be discharged.

[0052] To ensure absolute cleanliness of the microchannels, the array-type microball valve 1 and array-type microball valve 2 are physically assembled with the exhaust port 203 and air inlet 202 of the pump body 2 using a small interference fit without adhesive. This assembly not only eliminates secondary contamination from glue but also achieves reliable sealing of the perimeter using interference compression.

[0053] 1. Intake stroke: such as Figure 4 As shown in Figure a, when the piezoelectric vibrator 3 bends and deforms downward under the action of the alternating electric field, the volume of the pump chamber 201 increases instantaneously, and the gas pressure inside the chamber decreases, forming a negative pressure. At this time, the outlet valve, i.e., the array-type micro-ball valve 1, achieves a hard seal closure under the active pressure of the external high gas pressure and the elastic pressure rod; while the micro-ball valve core of the inlet valve, i.e., the array-type micro-ball valve 2 4, is pushed open against the stiffness force of the elastic pressure rod, and the external gas is rapidly drawn into the pump chamber 201 from the air inlet 202.

[0054] 2. Exhaust stroke: such as Figure 4As shown in Figure b, when the piezoelectric vibrator 3 bends and deforms upwards, the volume of the pump chamber 201 is rapidly compressed, and the pressure inside the chamber surges. At this time, the array-type micro-ball valve 4 is instantly forced to close under the dual action of the high pressure in the pump chamber and the elastic pressure rod. Due to the use of rigid micro-ball hard seal, there will never be a situation where the polymer membrane collapses backward and leaks, thus achieving high back pressure cutoff; while the array-type micro-ball valve 1 is pushed open by the high pressure inside the chamber, and the gas is directionally compressed and pumped out from the exhaust port 203.

[0055] Driven by high-frequency alternating current above 20kHz, the aforementioned micron-level intake and exhaust actions occur more than 20,000 times per second. Thanks to the extreme response speed and absolute pressure holding capability of the microball valve assembly of this invention within microseconds, the minute volume changes at the microscopic level are efficiently accumulated and ultimately converge on the macroscopic scale into a continuous, stable, high-back-pressure, high-flow-rate airflow output, perfectly meeting the silent air-cooling and fluid transport requirements of high-end equipment.

[0056] In summary, this invention, through a novel structural design using a micron-level rigid sphere, a metal cantilever beam elastic pressure bar, a high-density array arrangement, and glue-free solder ball riveting encapsulation, achieves significantly superior technical effects compared to existing technologies in five dimensions: ultra-high frequency responsiveness, high back pressure holding capability, high flow rate output, long lifespan reliability, and micro-nano packaging technology.

[0057] In the description of this invention, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not 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 invention. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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 between two elements. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0058] It should be noted that in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0059] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention described herein.

Claims

1. An array-type micro-ball valve for a piezoelectric micro-pump, characterized in that, include: A valve chamber plate (101) is provided with a plurality of valve chamber holes (1012) arranged in an array. Each valve chamber hole (1012) is a stepped hole, a hole with a sudden change in diameter, or a hole with a gradual change in diameter. It includes an air inlet (10121), a valve core cavity (10122), and an air outlet (10123) that are coaxially connected. The diameter of the air inlet (10121) is smaller than the diameter of the valve core cavity (10122). Multiple microball valve cores (103) are provided, each of which is independently and movably disposed in a corresponding valve core cavity (10122), and the microball valve core (103) is a rigid sphere; A limiting plate (102) is stacked and fixedly disposed with the valve cavity plate (101); an elastic pressure rod (1023) is provided on the limiting plate (102) corresponding to each valve cavity hole (1012), the elastic pressure rod (1023) is a cantilever beam structure, and its free end abuts against the micro ball valve core (103). In the non-working state or the reverse pressure state when the valve is closed, the elastic pressure rod (1023) presses the microball valve core (103) against the air inlet (10121) to form a line contact hard seal; in the forward pressure state when the valve is open, when the fluid pressure difference is greater than the stiffness force of the elastic pressure rod (1023), the microball valve core (103) pushes up the elastic pressure rod (1023) to make it elastically deform, thereby opening the air inlet (10121).

2. The array-type micro-ball valve for a piezoelectric micro-pump according to claim 1, characterized in that, The microsphere valve core (103) is a ceramic microsphere or a metal microsphere with a diameter between 0.05 mm and 1 mm.

3. The array-type micro-ball valve for piezoelectric micro-pumps according to claim 1, characterized in that, The valve cavity holes (1012) on the valve cavity plate (101) are arranged in a rectangular array; multiple connecting plates (1022) are arranged at intervals on the limiting plate (102), and the elastic pressure rod (1023) is set on the connecting plate (1022) and extends to both sides, corresponding to the positions of the valve cavity holes (1012) on the adjacent sides.

4. The array-type micro-ball valve for a piezoelectric micro-pump according to claim 3, characterized in that, The projected geometric space of the valve cavity plate (101) is rectangular or circular, with a length not greater than 10mm and a width not greater than 8mm, or a diameter not greater than 10mm; the number of valve cavity holes (1012) is at least two rows and two columns or two rows and two columns.

5. The array-type micro-ball valve for a piezoelectric micro-pump according to claim 1, characterized in that, The elastic pressure bar (1023) is made of metal and has a width of 0.02mm to 0.8mm and a cantilever length of 0.03mm to 1.5mm.

6. The array-type micro-ball valve for a piezoelectric micro-pump according to any one of claims 1 to 5, characterized in that, The valve chamber plate (101) and the limiting plate (102) are provided with a riveting hole one (1011) and a riveting hole two (1021) aligned in position. The two plates are fixedly connected by riveting or welding through a solder ball riveting body (104) inserted into the riveting hole; or they can be made from a single plate using a semi-etching process.

7. The array-type micro-ball valve for a piezoelectric micro-pump according to claim 6, characterized in that, The main structures of the valve chamber plate (101) and the limiting plate (102) are both integrally formed from metal through an etching process; the microball valve core (103) is integrally formed from metal or ceramic material.

8. A piezoelectric micro-pump, characterized in that, include: Pump body (2), a pump chamber (201) is formed inside the pump body (2), and an air inlet (202) and an exhaust port (203) communicating with the pump chamber (201) are provided on the pump body (2). A piezoelectric vibrator (3) is sealed to the pump body (2) and forms at least a portion of the wall of the pump cavity (201), and is used to generate reciprocating bending deformation under the drive of an alternating electric signal to change the volume of the pump cavity (201). It also includes at least two array-type micro-ball valves as described in any one of claims 1 to 7, namely a first array-type micro-ball valve (1) and a second array-type micro-ball valve (4), wherein one of the array-type micro-ball valves is installed at the air inlet (202) and its unidirectional conduction direction points to the inside of the pump chamber (201), and the other array-type micro-ball valve is installed at the exhaust port (203) and its unidirectional conduction direction points away from the pump chamber (201) and outwards.

9. The piezoelectric micro-pump according to claim 8, characterized in that, The array-type micro ball valve one (1) and array-type micro ball valve two (4) are assembled with the air inlet (202) and exhaust port (203) of the pump body (2) by an interference fit without adhesive.

10. The piezoelectric micro-pump according to claim 8, characterized in that, The operating frequency of the piezoelectric vibrator (3) is configured to be no less than 20kHz, and the vibration amplitude of the piezoelectric vibrator (3) is configured to be 1μm to 20μm.

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