An acoustically enhanced driven parallel piezoelectric micropump and its driving method

Abstract

The present invention discloses an acoustically enhanced driven parallel piezoelectric micropump and its driving method; it includes an input layer, a support structure, and an output layer stacked in sequence; characterized in that: it further includes a plurality of actuators arranged in the support structure. Each actuator is arranged in a straight line queue or in a matrix. An integrated input chamber is formed between each actuator and the input layer. A plurality of independent output chambers are formed between each actuator and the output layer. The actuator is used to pump fluid through its own vibration. The input layer is provided with a plurality of inflow structures staggered from the flow-through structures on the actuator. The output layer is provided with a plurality of outflow structures aligned with the flow-through structures on the actuator. The present invention realizes the coupling of acoustic vibration and mechanical vibration by the way of paralleling multiple pump flow units, and arranges a plurality of inflow structures at multiple antinodes of acoustic resonance to further enhance the fluid flow and improve the pumping efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of piezoelectric fluid micro - pumps, and particularly relates to a parallel - type piezoelectric micro - pump with acoustic - enhanced driving and a driving method thereof. Background Art

[0002] Driven by Generative AI (GAI) technology, the heat problem associated with smartphones is difficult to solve solely by passive heat - dissipation technology. The piezoelectric active air - cooling / liquid - cooling heat - dissipation solutions prepared by applying Micro - Electro - Mechanical Systems (MEMS) technology can well solve this problem. Among them, due to the risk of liquid leakage in liquid - cooling pumps, their universality is far less than that of air - cooling heat - dissipation solutions.

[0003] Traditional active air - cooling devices are limited in their application on mobile phones due to their large thickness and high power consumption. In addition, traditional fans have some other drawbacks. For example, they produce relatively high noise, which affects the user experience; mechanical components are prone to wear, resulting in a short service life; and it is difficult to achieve precise air - volume control and dynamically adjust according to the actual heat - dissipation requirements of the device. The structures of traditional piezoelectric micro - pumps are mostly fixed around the periphery, and there is a relatively high residual stress in the central membrane layer, which weakens their vibration.

[0004] Traditional piezoelectric micro - pumps also have certain limitations in terms of heat - dissipation efficiency and stability. For example, in order to achieve higher - performance output, multiple heat - dissipation units often need to be connected in parallel. However, simple parallel connection easily leads to fluid disorder inside the parallel chambers, thus failing to achieve the desired performance improvement. To further improve the performance of piezoelectric micro - pumps, it becomes possible to improve their driving efficiency through acoustic enhancement. The parallel - type piezoelectric micro - pump with acoustic - enhanced driving utilizes the coupling of sound waves and mechanical vibrations, which can significantly improve the fluid flow efficiency, thereby achieving more efficient heat - dissipation.

[0005] By using acoustic coupling with mechanical vibration, the fluid flow is enhanced through sound - wave vibration to improve the pumping efficiency. The Helmholtz resonator is a classic acoustic resonance structure, and its resonance frequency can be precisely controlled by adjusting the cross - sectional area and volume of the cavity. Applying the principle of the Helmholtz resonator to the design of piezoelectric micro - pumps, by adjusting the width and height of the input chamber, the acoustic resonance frequency inside the chamber is made to match the mechanical resonance frequency of the piezoelectric micro - pump, thereby achieving the coupled resonance of sound - wave vibration and mechanical vibration and enhancing the fluid flow efficiency by 30% - 50%. Its simple and reliable design and optimized control ability give it a competitive advantage in the market and are expected to become the mainstream development direction of future micro - pump technology. Summary of the Invention

[0006] The object of the present invention is to provide a parallel piezoelectric micropump driven by acoustic enhancement to achieve more efficient heat dissipation in applications such as heat dissipation of electronic devices. By utilizing the principle of Helmholtz resonance cavity and coupling acoustic and mechanical vibrations, higher performance output can be achieved. Combining micro-nano processing techniques, a device structure with lower power consumption and smaller size can be realized. Through specific structures and driving methods, the present invention can simultaneously achieve the functions of forward pumping heat dissipation and reverse self-cleaning under excitation at different frequencies, thereby providing continuous and stable heat dissipation output performance.

[0007] In a first aspect, the present invention provides a parallel piezoelectric micropump driven by acoustic enhancement, including an input layer, a support structure, and an output layer stacked in sequence; characterized in that: it further includes a plurality of actuators arranged in the support structure. Each actuator is arranged in a straight line queue or in a matrix. An integrated input chamber is formed between each actuator and the input layer. A plurality of independent output chambers are formed between each actuator and the output layer. The actuator is used to pump fluid through its own vibration.

[0008] A plurality of inflow structures are provided on the input layer. The positions of the inflow structures are offset from the through-flow structures on the actuators. The vibrating actuator forms a standing wave in the acoustic vibration in the input chamber; the positions of the multiple wave antinode points of the standing wave are aligned with the positions of the respective inflow structures. A plurality of outflow structures corresponding to the respective output chambers are provided on the output layer. The positions of the outflow structures are aligned with the through-flow structures on the actuators.

[0009] Preferably, the positions of the inflow structures are all aligned with the connection between two adjacent actuators or the edge of the actuator at the end.

[0010] The center-to-center distance P between adjacent inflow structures, the length L and width of the input chamber satisfy the following relationship:

[0011]

[0012] wherein, is the zero point of the Bessel function.

[0013] Preferably, the operating vibration frequency of the actuator and the acoustic resonance frequency a of the input chamber satisfy the following relationship: 0.8f ≤ f

[0014] ≤ 1.2f. Preferably, the acoustic resonance frequency of the input chamber is 18 kHz to 22 kHz; the acoustic resonance frequency of the input chamber is adjusted by the length L and width of the input chamber.

[0015] Preferably, each actuator corresponds to a pump flow unit; the length of the pump flow unit is 3 mm to 4 mm.

[0016] Preferably, the actuator includes two actuator units arranged side by side. The actuator unit includes a vibrating plate, a flexible sealing structure, and a vibrating element. The four peripheral edges of the vibrating plate are respectively a fixed edge, a movable edge, and two swinging edges. The fixed edges of the vibrating plates in the two actuator units are respectively fixed on two opposite side surfaces inside the support structure. A flow-through gap is formed between the movable edges of the vibrating plates in the two actuator units. The swinging edges of the vibrating plate are connected to the inside of the support structure with a flexible sealing structure.

[0017] Preferably, a groove structure is provided on the side surface of the vibrating plate close to the output chamber. The width of the groove structure is less than or equal to 60 μm, and the depth is less than or equal to 50% of the thickness of the vibrating plate; the distance between the groove structure and the flow-through gap is less than or equal to 30 μm.

[0018] Preferably, the actuator includes four actuator units arranged in a surrounding manner. The actuator unit includes a vibrating plate and a vibrating element. One side edge of each vibrating plate away from the center position of the actuator is fixed to the inner cavity of the support structure. The remaining edges of different vibrating plates form a flow-through gap.

[0019] Preferably, the shapes of the four actuator units adopt any one of the following two schemes.

[0020] Scheme 1: All four actuator units are triangular. The flow-through gaps between the four actuator units are in an X shape.

[0021] Scheme 2: Two of the actuator units are triangular, and the other two actuator units are trapezoidal. The two triangular actuator units and the two trapezoidal actuator units are alternately arranged around the center of the actuator in sequence.

[0022] In a second aspect, the present invention provides a pump gas driving method, which uses a parallel piezoelectric micropump with acoustic enhanced driving as described above; characterized in that: the pump gas driving method includes a forward pump gas method and a reverse self-cleaning method;

[0023] The forward pump gas method is: applying excitation signals with the same frequency and the same phase to different vibrating elements in the same actuator; each actuator unit in the same actuator vibrates synchronously in the same direction, driving the air flow to enter from the air inlet structure, passing through the input chamber, the flow-through gap, and the output chamber, and then outputting from the air outlet structure;

[0024] The reverse self-cleaning method is as follows: different excitation signals are applied to different vibration elements in the same actuator, and each actuator unit in the same actuator vibrates asynchronously. The gas in the piezoelectric micropump flows reversely during part or all of the operation time, and the air flow enters from the air outlet and is output from the air inlet.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1. By connecting multiple pump flow units in parallel, the present invention realizes the coupling of acoustic vibration and mechanical vibration, and arranges multiple inflow structures at multiple antinodes and nodes of acoustic resonance, further enhancing the fluid flow and improving the pumping efficiency.

[0027] 2. By regulating the number and arrangement mode of the parallel pumping units, the present invention can adjust the length and width of the input chamber without changing the structure of each pumping unit, so as to realize the regulation of the resonance frequency of the input chamber. Furthermore, while controlling the mechanical vibration frequency of the actuator at a relatively low level (about 20 kHz), the mechanical vibration frequency is made close to the resonance frequency of the input chamber. Therefore, the present invention can minimize mechanical losses as much as possible on the premise of generating coupled vibration, and further improve the energy conversion efficiency.

[0028] 4. The groove structure opened on one side of the vibration plate close to the flow-through gap in the present invention helps to relieve the pressure generated in the output chamber during the pumping process, so that the resistance received by the vibration plate during vibration is smaller, the amplitude of the actuator is increased, and the pumping performance is further improved.

[0029] 5. Compared with the traditional piezoelectric pump with a fixed perimeter, the actuator in the present invention adopts an up-and-down reciprocating vibration form, reducing the influence of residual stress on piezoelectric devices. At the same time, by applying different excitation signals to the vibration elements on the vibration plate, the present invention can realize the function of reverse self-cleaning, and is more suitable as a heat dissipation element for electronic devices, with a wide range of application scenarios. Description of the Drawings

[0030] Figure 1 It is a schematic cross-sectional structure diagram of Embodiment 1 of the present invention.

[0031] Figure 2 It is a schematic diagram of the standing wave distribution generated by acoustic vibration in the parallel input chambers in Embodiment 1 of the present invention.

[0032] Figure 3 It is a comparison diagram of the analytical solution and simulation solution of the Helmholtz resonance width and acoustic vibration frequency.

[0033] Figure 4 It is a schematic structure diagram of the actuator in Embodiment 1 of the present invention.

[0034] Figure 5 Schematic diagram of the working mode of forward pump flow for Embodiment 1 of the present invention.

[0035] Figure 6 Schematic diagram of the working mode of reverse self-cleaning for Embodiment 1 of the present invention.

[0036] Figure 7 Exploded view of the device with four pump flow units in parallel in Embodiment 2 of the present invention.

[0037] Figure 8 Exploded view of the device with eight pump flow units in parallel in Embodiment 2 of the present invention.

[0038] Figure 9 Schematic diagram of the structure of the actuator in Embodiment 3 of the present invention.

[0039] Figure 10 Schematic diagram of the structure of the actuator in Embodiment 4 of the present invention.

[0040] Figure 11 Schematic diagram of the structure of the actuator in Embodiment 5 of the present invention.

[0041] Figure 12 Schematic diagram of the structure of the actuator in Embodiment 6 of the present invention. Detailed implementation manners

[0042] The present invention will be further described below with reference to the accompanying drawings.

[0043] Embodiment 1

[0044] As Figure 1 shown, an acoustically enhanced driven parallel piezoelectric micropump includes an input layer 10, a support structure 40, an output layer 30 which are sequentially stacked, and a plurality of actuators arranged in a straight line queue. The support structure 40 is a hollow structure with both ends open, and a vertical partition is provided inside. The bottom of the partition is connected to the output layer 30. The top of the partition is spaced from the input layer 10. The partition divides the inner cavity range of the support structure 40 into a plurality of pump flow regions arranged side by side. The number of actuators is equal to and corresponds one by one to the number of pump flow regions.

[0045] Each actuator is respectively arranged in the corresponding pump flow region. In the initial state, the top surface of the actuator is flush with the top surface of the partition. An integrated input chamber 100 is formed between each actuator and the input layer 10. A plurality of output chambers 200 which are separated by the partition and independent of each other are formed between each actuator and the output layer 30. Each actuator and the corresponding input chamber 100 and output chamber 200 together form a pump flow unit.

[0046] The actuator is used to transfer the fluid in the input chamber 100 to the output chamber 200 through the flow-through structure in the actuator by its own vibration, so as to realize the continuous pumping of the fluid of the pump flow unit. The flow-through structure is located in the middle of the actuator.

[0047] As Figure 1 shown, inlet structures 11 are provided at both side edges of the input layer 10 and at positions aligned with the partition; three inlet structures 11 are formed at the position farthest from the flow-through structure of the actuator; therefore, the middle inlet structure 11 is located at the connection of adjacent pump flow units. Two outlet structures 31 are provided on the output layer 30. The two outlet structures 31 are respectively aligned with the flow-through structures of the two actuators. The outlet structure 31 is strip-shaped, and the length direction is parallel to the length direction of the flow-through gap 300.

[0048] As Figure 2 shown, the overall structured input chamber 100 can be approximately regarded as a Helmholtz resonator. When the pump flow unit is driven, acoustic vibrations can be generated inside the input chamber, thus forming a standing wave. When the vibration frequency of the pump flow unit is close to the acoustic resonance frequency of the input chamber 100, the fluid can be driven more effectively.

[0049] For a Helmholtz resonator, its resonance frequency can be expressed as:

[0050] where is the zero of the Bessel function; is the resonance frequency of the input chamber 100; is the speed of sound; L, are respectively the length and width of the input chamber. The length of the input chamber is the dimension parallel to the arrangement direction of the pump flow units.

[0051] When the vibration frequency of the actuator is close to the acoustic resonance frequency , the acoustic vibration and the mechanical vibration will be coupled and resonate, so as to enhance the amplitude of the mechanical vibration and improve the performance; in this embodiment takes 0.8f to 1.2f.

[0052] Furthermore, regarding the relationship between the length L and the height H of the input chamber 100 that the present invention pays more attention to, it should satisfy:

[0053]

[0054] Since the height differs by more than one order of magnitude from the length and width, it is ignored, and the focus is on the length L of the input chamber. A shorter length L of the input chamber will result in a higher acoustic resonance frequency , therefore, to couple acoustic vibrations with mechanical vibrations, the acoustic resonance frequency can be reduced or the mechanical vibration frequency can be increased in two aspects.

[0055] For piezoelectric materials or elastic materials, mechanical losses usually show the following several dependencies on frequency: at low frequencies, it shows a linear relationship: in some simplified models, mechanical losses are linearly related to frequency, especially in the low-frequency region or for certain specific materials; in some high-frequency cases, especially considering factors such as internal friction, viscosity, and structural vibration of the material, mechanical losses may be proportional to the square of the frequency. This relationship usually appears under certain specific conditions, such as under high-frequency excitation, the internal friction of the material will increase significantly.

[0056] Therefore, although mechanical vibrations driven at high frequencies can also couple with acoustic vibrations, higher frequencies will bring greater mechanical losses and reduce the energy conversion efficiency. In this embodiment, the mechanical vibration frequency is 18 kHz to 22 kHz.

[0057] As Figure 3 shown, further, since the length of a single pump flow unit in this embodiment is controlled within 3 mm to 4 mm, the pump flow units are connected in parallel in this embodiment to increase the length L of the input chamber, thereby reducing the acoustic resonance frequency and controlling the mechanical vibration frequency and the acoustic resonance frequency at a relatively low level, thus effectively improving the energy conversion efficiency; for example, if the acoustic resonance frequency is controlled at 20 kHz, the length L of the input chamber should be controlled within 6 mm to 8 mm, that is, the number of pump flow units along the length direction is preferably two.

[0058] As Figure 5 shown, when the integral input chamber 100 formed by connecting the pump flow units in parallel satisfies the acoustic resonance condition, the acoustic vibrations generated can form a standing wave. At this time, the fluid flow efficiency at the node TT of the standing wave is weak; while the fluid at the antinode TB of the standing wave is affected by the acoustic vibrations and the flow efficiency is enhanced. Therefore, in the present invention, the inflow structure 11 is arranged at the antinode TB of the standing wave to enhance the fluid flow at the inlet.

[0059] The distance between adjacent antinodes TB is equal to half of the wavelength of the acoustic standing wave , and the standing wave wavelength can be simply obtained from the acoustic resonance frequency, that is

[0060]

[0061] where is the speed of sound wave propagation (usually 344 m / s in air), is the frequency of the acoustic vibration.

[0062] Therefore, taking the center distance P between two adjacent inflow structures 11, the length L and width of the input chamber 100 Satisfy the following relational expressions:

[0063]

[0064]

[0065] By combining the above equations, it can be obtained that, in an ideal situation, the optimal relationships among the length L, width of the input chamber 100 , and the center distance P between adjacent inflow structures 11 are as follows:

[0066]

[0067] At the same time, since the center distance P between the inflow structures 11 is the same as the length of the pump flow unit; and the number n of pump flow units in the length direction is an integer, so n = L / P is a positive integer.

[0068] In this embodiment, L, W, and P are taken as 8 mm, 3 mm, and 4 mm respectively, and the number n of arrays in the length direction is taken as 2.

[0069] In this embodiment, multiple output chambers 200 are independent of each other, and their main purpose is to ensure stable performance output of a single pump flow unit. Compared with connecting the input chamber 100, limited by the position of the outflow structure 30 of the output chamber (it must be opposed to the through-flow gap 300), therefore, connecting the output chambers may cause the same acoustic wave vibration to inhibit the fluid flow inside the output chamber 200. Further, the through-flow gap 300 is arranged at the wave node of the standing wave formed by connecting the input chamber 100 to prevent the acoustic wave vibration from affecting the fluid flow inside the output chamber 200.

[0070] In this embodiment, the number of pump flow units is two; in some other embodiments, the number of parallel-connected pump flow units can be more than two, such as 4, 8 or more, but at least it is necessary to ensure that the length of the input chamber 100 after array is not less than 2000 μm, and the vibration frequency of the actuator is 18 kHz to 22 kHz.

[0071] In this embodiment, the actuator adopts a side-by-side double-swing oscillator structure, and a gap serving as a through-flow structure is formed by two independent oscillators that can swing up and down; the synchronous vibration of the two oscillators realizes continuous fluid pumping. In some other embodiments, the actuator can also adopt other piezoelectric oscillator structures, such as a ring oscillator structure with a central hole.

[0072] In this embodiment, the actuator with a double-swing oscillator structure includes two actuator units arranged left and right. The opposite sides of the two actuator units are fixedly connected to a set of opposite side surfaces in the corresponding pump flow regions of the support structure 40 respectively. The arrangement direction of the two actuator units is the same as that of the two pump flow units.

[0073] As Figure 1 and Figure 4 shown, a flow-through gap 300 is formed between the adjacent sides of the two actuator units. The actuator unit includes a vibrating plate 20, a flexible sealing structure 51, and a vibrating element. The four peripheral edges of the vibrating plate 20 are a fixed edge, a movable edge, and two swinging edges respectively. The two swinging edges are one pair of opposite sides of the vibrating plate 20; the fixed edge and the movable edge are the other pair of opposite sides of the vibrating plate 20. The fixed edge of the vibrating plate 20 is fixed to the inner side surface of the corresponding pump flow region. The two swinging edges of the vibrating plate 20 are close to the corresponding inner side walls on the support structure 40 and there is a flow-through gap 300 left.

[0074] A flexible sealing structure 51 is connected between the two swinging edges of the vibrating plate 20 and the corresponding side walls or partitions inside the support structure 40. One side of the flexible sealing structure 51 is adhesively fixed to the swinging edge of the vibrating plate 20, and the other side is fixed to the side wall or partition inside the support structure 40. The flexible sealing structure 51 seals the gap between the swinging edge of the vibrating plate 20 and the inner side wall of the support structure 40, realizing the sealing between the two swinging edges of the vibrating plate 20 and the inner side surface of the pump flow region, so that the fluid only flows through the flow-through gap 300 during the operation of the piezoelectric micropump. The flexible sealing structure 51 can expand and contract with the up-and-down swing of the vibrating plate 20, so it will not affect or limit the reciprocating swing of the vibrating plate 20.

[0075] In this embodiment, the flexible sealing structure 51 is made of a polymer material that can expand and contract in a large proportion without being damaged, preferably Parylene C or other xylene-based polymers. The flexible sealing structure 51 can block the fluid from passing through the free side of the vibrating plate 20 without affecting the vibration of the actuator, so that the fluid can only pass through the flow-through gap 50, thereby improving the overall pressure and flow output of the device.

[0076] In this embodiment, the pump flow unit is square, and the width or diameter is less than or equal to 3000 μm (preferably 2000 μm). The material of the support structure 40 is one or more of stainless steel, silicon, silicon compounds, and germanium compounds.

[0077] Since the two actuator units of the actuator in this embodiment are independent of each other and form a flow-through gap 300, the actuator in this embodiment will not generate residual stress at the center during the vibration process like the conventional annular actuator structure fixed around.

[0078] One side of all the vibrating elements is commonly grounded, and the other sides are respectively connected to independent power supply control interfaces, enabling all the vibrating elements in this embodiment to be independently controlled. For each pump flow unit, by applying driving signals with different frequencies or the same frequency but different phases to the vibrating elements in the two actuating units, asynchronous vibration of the two actuating units can be achieved.

[0079] In some other embodiments, one of the vibrating elements in the same actuator is called the first vibrating element, and the other vibrating element is called the second vibrating element; the first vibrating elements in all actuators are controlled in parallel; the second vibrating elements in all actuators are controlled in parallel; thus, while achieving independent control of the two vibrating elements in the same actuator, synchronous control of different actuators is performed; on the one hand, reverse pumping self-cleaning of the pump flow unit can be achieved through asynchronous control, and on the other hand, the complexity of the control circuit is reduced.

[0080] In this embodiment, the initial width of the flow-through gap 300 is controlled between 1 μm and 10 μm; when the actuator is in a stationary state, the flow-through gap 300 with a width of only 1 μm to 10 μm can be approximately considered closed, that is, the fluid cannot pass through the flow-through gap 300 or only a small amount of fluid can pass through (which can be ignored).

[0081] The flow-through gap 300 and two mutually independent vibrating plates 20 are obtained by etching and dividing a complete laminate structure in the middle. The two vibrating elements can either be generated by dividing a large piece of piezoelectric material after etching the flow-through gap 300, or be formed by sputtering at two symmetric positions of the actuator respectively. The vibrating elements are made of piezoelectric materials, usually one of lead zirconate titanate and aluminum nitride, with a thickness of 2 μm.

[0082] In this embodiment, the inlet structure 11 is in a long strip shape, and the length direction is parallel to the length direction of the flow-through gap 300; the inlet structure 11 can either adopt a long strip-shaped through-channel structure or a queue through-hole structure formed by arranging multiple through-holes in sequence. The width of the input position of the inlet structure 11 is between 30 μm and 50 μm (preferably 40 μm), and the inlet structure 11 in the middle parallel part is slightly wider than the two sides by 10 to 20 μm.

[0083] In this embodiment, the outlet structure 31 can either adopt a long strip-shaped through-channel structure or a queue through-hole structure formed by arranging multiple through-holes in sequence. The width of the output position of the outlet structure 31 is controlled between 100 μm and 120 μm (preferably 110 μm).

[0084] Each inlet flow structure 11 of the input layer 10 is an inlet flow gradient channel structure with a larger inner portion and a smaller outer portion. Each outlet flow structure 31 of the output layer 30 is an outlet flow gradient channel structure with a larger inner portion and a smaller outer portion. The gradient channel structure can be a stepped structure or a smoothly transitioned inclined plane structure or a curved surface structure.

[0085] In the initial state, the height of the input chamber 100 is greater than the height of the output chamber 200 . In this embodiment, the height of the input chamber 100 is greater than or equal to 300 μm; and the height of the output chamber 200 is less than or equal to 120 μm.

[0086] The inner side of the input layer 10 (i.e., the side close to the actuator) is provided with an air intake concave structure 12 connected to the air intake port 11 on both side edges. The air intake concave structure 12 forms an air intake gradient flow channel structure with a large inner side and a small outer side at the air intake port 11. Since the height of the input chamber 100 is greater than or equal to 300 μm and has sufficient height space, when the actuator vibrates toward the input layer 10, the fluid entering the input chamber 100 generates a vortex at the air intake gradient flow channel structure with a large inner side and a small outer side due to the Bernoulli principle, thereby inhibiting the fluid from flowing back to the outside of the air intake port.

[0087] The middle of the inner side surface (i.e., the side surface close to the actuator) of the output layer 30 is provided with an outlet concave structure 32 of the outlet 31. The width of the outlet concave structure 32 is greater than the width of the outlet 31, so that an outlet gradient flow channel structure with a larger inner side and a smaller outer side is formed at the outlet 31; since the height of the output chamber 200 is less than or equal to 120 μm, the flow gap 300 is closer to the outlet 31 during vibration, and the fluid near the outlet gradient flow channel structure will be compressed sharply, causing the temperature of the fluid to rise, thereby helping to increase the flow rate, and improving the pumping efficiency without increasing the aperture of the flow hole.

[0088] In some embodiments, the parallel piezoelectric micropump is prepared by micro-nano technology, as follows:

[0089] (1) Processing to obtain a device embryo formed by stacking a substrate, an insulating layer, and a structural layer in sequence;

[0090] (2) forming a piezoelectric layer on the structural layer, and etching the piezoelectric layer to form a vibration element 21;

[0091] (3) forming a top electrode on the vibration element 21;

[0092] (4) The structural layer is etched to form a plurality of I-shaped gaps arranged in an array; each I-shaped gap corresponds to two vibration elements 21. The plurality of I-shaped gaps form vibration plates in the plurality of actuators.

[0093] (5) Setting a protective layer on the front side of the device and etching the back side of the substrate to form multiple independent output chambers;

[0094] (6) The protective layer is removed, and the contact sealing structure 50 is connected to the swinging edges on both sides of each vibration plate to obtain a micro pump body; the output layer 30, the part of the support structure 40 away from the output layer 30, and the input layer 10 are connected to the micro pump body through a bonding process.

[0095] The silicon-based piezoelectric micropump prepared by micro-nano technology has a smaller size and lower power consumption.

[0096] The working principle of the piezoelectric micropump with parallel double oscillators provided in this embodiment is as follows:

[0097] The two actuating units of each actuator can be driven by an excitation signal to generate vibrations toward the input layer 10 or the output layer 30. By applying the same or different excitation signals to the vibration elements in the two actuating units, the actuator generates two different vibration modes to achieve two different functions of forward pump flow and reverse self-cleaning.

[0098] like Figure 5 As shown, the forward pump flow process is: applying an excitation signal of the same frequency and phase to the two vibration elements of all pump flow units, and the two vibration plates 20 vibrate in the same direction (vibrate in the same direction) driven by the vibration elements, so that the volume inside the micro pump changes, and a pressure difference is generated inside and outside. When the two vibration plates 20 swing in the direction close to the output layer 30 at the same time, the volume of the connected input chamber 100 increases, while the volume of the output chamber 200 decreases. At the same time, a standing wave formed by acoustic vibration is generated inside the connected input chamber 100. The fluid is affected by the acoustic vibration and enters the pump body through the inlet structure 11 on the input layer 10, and there is a tendency to flow in the direction close to the flow gap 300. At the same time, the distance between the vibration plate 20 and the outflow concave structure 32 gradually decreases, and the fluid near the outflow structure 31 inside the output chamber 200 is sharply compressed, and the fluid viscosity increases, so that the fluid inside the output chamber 200 is mainly pumped out from the outflow structure 31 and will not flow back to the input chamber 100 through the flow gap 300;

[0099] When the vibration plate 20 swings toward the input layer 10 at the same time, the volume of the connected input chamber 100 decreases, while the volume of the output chamber 200 increases. Since the height of the connected input chamber 100 is higher than that of the output chamber 200, when the actuator vibrates toward the input layer 10, the stepped structure with a larger inside and a smaller outside will generate a vortex at the stepped structure due to the Bernoulli principle, thereby inhibiting the fluid from flowing back to the outside of the inlet structure, and more fluid flows from the input chamber 100 through the flow gap 300 into the output chamber 200, forming a circulation.

[0100] like Figure 6As shown, the reverse self-cleaning process is as follows: Two different excitation signals are respectively applied to the two vibrating elements of the same pump flow unit; in this embodiment, there is a certain difference in the frequencies of the two different excitation signals, which is set to 50 Hz in this embodiment, so that the two actuating units vibrate asynchronously, and the width of the flow-through gap 300 between the two vibrating plates 20 changes significantly; at this time, the fluid inside the piezoelectric micropump will flow reversely, which is different from the forward pump flow, so that the air flow enters from the outflow structure 31, passes through the output chamber 200, the flow-through gap 300 and the input chamber 100, and then is output from the inflow structure 11. To achieve that while the first vibrating element 22 vibrates towards the input layer 10, the second vibrating element 23 vibrates towards the output layer 30, and vice versa.

[0101] In this embodiment, reverse self-cleaning can blow away the dust blocked at the inflow structure 11 during the forward pump flow process, play a role in cleaning the dust, and restore the flow rate drop of the piezoelectric micropump caused by the blockage of the inflow structure 11, so that the piezoelectric micropump continuously and efficiently blows air to dissipate heat from the external heat-generating structure.

[0102] Embodiment 2

[0103] A parallel piezoelectric micropump using acoustic enhancement drive, the difference between this embodiment and Embodiment 1 is that: the partition in the support structure 40 is in a grid-like structure, so that a plurality of pump flow regions arranged in a multi-row and multi-column matrix are formed inside the support structure 40. An actuator is provided in each pump flow region, forming a plurality of pump flow units arranged in a matrix.

[0104] In some embodiments, the number of pump flow units in the width direction of the parallel piezoelectric micropump is two; further preferably, as Figure 7 shown, in the case of a total of four pump flow units, the four pump flow units are arranged in a 2×2 matrix. As Figure 8 shown, in the case of a total of eight pump flow units, the eight pump flow units are arranged in a 2×4 matrix, but not limited thereto.

[0105] Embodiment 3

[0106] A parallel piezoelectric micropump using acoustic enhancement drive, the difference between this embodiment and Embodiment 1 is that: the structure of the vibrating plate 20 is different; a rectangular groove 24A is opened at a position close to the flow-through gap 300 on the side of the vibrating plate 20 close to the output chamber 200. The rectangular groove 24A is formed by etching. The rectangular groove 24A is not directly communicated with the flow-through gap 300.

[0107] As Figure 9As shown, the presence of the rectangular grooves 24A on the two vibrating plates 20 forms additional chambers at the bottoms of the two vibrating plates 20, which helps to relieve the pressure generated in the output chamber 200 during the pumping process, and further reduces the resistance suffered by the two vibrating plates 20 during vibration, thereby increasing the amplitude of the actuator. In this embodiment, the width of the rectangular groove 24A is less than 60 μm, and the depth is less than or equal to 50% of the thickness of the vibrating plate 20; the distance between the rectangular groove 24A and the flow-through gap 300 is not greater than 30 μm.

[0108] Embodiment 4

[0109] A parallel piezoelectric micropump using acoustic enhancement drive. The difference between this embodiment and Embodiment 1 lies in: the structure of the vibrating plate 20 is different; an arc-shaped groove 24B is provided at a position close to the flow-through gap 300 on the side of the vibrating plate 20 close to the output chamber 200. The arc-shaped groove 24B is formed by etching. The arc-shaped groove 24B is not directly communicated with the flow-through gap 300.

[0110] As Figure 10 shown, the presence of the arc-shaped grooves 24B on the two vibrating plates 20 forms additional chambers at the bottoms of the two vibrating plates 20, which helps to relieve the pressure generated in the output chamber 200 during the pumping process, and further reduces the resistance suffered by the two vibrating plates 20 during vibration, thereby increasing the amplitude of the actuator. In this embodiment, the width of the arc-shaped groove 24B is less than 60 μm, and the depth is less than or equal to 50% of the thickness of the vibrating plate 20; the distance between the arc-shaped groove 24B and the flow-through gap 300 is not greater than 30 μm.

[0111] Embodiment 5

[0112] An acoustic enhancement drive parallel piezoelectric micropump. The difference between this embodiment and Embodiment 1 lies in: the structure of the actuator is different.

[0113] As Figure 11 shown, in this embodiment, each actuator includes four actuator units. Each actuator unit is triangular, and together they enclose a rectangular actuator. The four actuator units together form an X-shaped flow-through gap 300. In this embodiment, no flexible sealing structure 51 is provided in the actuator unit. The vibrating plate 20 and the vibrating element 21 in the actuator unit are both isosceles triangles. The bottom edge of the vibrating plate 20 is fixed to the support structure 40; the waist edges of the vibrating plate 20 are used to form the flow-through gap 300.

[0114] The shapes of the inlet flow structure 11 and the outlet flow structure 31 are adjusted according to the shape of the flow-through gap 300, so that the inlet flow structure 11 is as far away from the flow-through gap 300 as possible; the outlet flow structure 31 maximizes the alignment area with the flow-through gap 300; for example, the inlet flow structure 11 is circular and is arranged in the middle of the connection line between two adjacent pump flow units. The circular inlet flow structure 11 can be acoustically enhanced in both the length and width directions, which helps to further improve the pumping efficiency; the outlet flow structure 31 is in an X shape aligned with the flow-through gap 300.

[0115] Compared with the structure of Embodiment 1, the actuator structure provided in this embodiment avoids the gap generated only between the double vibration plates 20 and the support structure 40, so there is no need to use polymers for sealing, reducing the complexity of the device. At the same time, the structure of the four vibration plates 20 is divided into four vibration units for driving, and the change in the chamber volume is larger, further enhancing the driving ability.

[0116] Embodiment 6

[0117] An acoustically enhanced driven parallel piezoelectric micropump. The difference between this embodiment and Embodiment 1 lies in the different structures of the actuators.

[0118] As Figure 12 shown, in this embodiment, each actuator includes four actuator units. Two of the actuator units are triangular, and the other two actuator units are trapezoidal. The two triangular actuator units and the two trapezoidal actuator units are alternately arranged in a ring structure in sequence to form a back-to-back double-Y-shaped flow-through gap. The flow-through gap is formed by the two waists of the triangular actuator unit, the upper base and the two waists of the trapezoidal actuator unit, and includes a middle straight gap and two sets of bifurcated gaps connecting the two ends of the middle straight gap.

[0119] In this embodiment, no flexible sealing structure 51 is provided in the actuator unit. Compared with the structure of Embodiment 1, the actuator structure provided in this embodiment avoids the gap generated only between the double vibration plates 20 and the support structure 40, so there is no need to use polymers for sealing, reducing the complexity of the device. At the same time, the structure of the four vibration plates 20 is divided into four vibration units for driving, and the change in the chamber volume is larger, further enhancing the driving ability. At the same time, the amplitude of the trapezoidal vibration plate 20 is larger than that of the triangular vibration plate 20, so the vibration in the trapezoidal direction of this structure is more obvious and is more suitable for the scenario of parallel use in this direction.

[0120] Embodiment 7

[0121] A piezoelectric heat dissipation system includes a parallel piezoelectric micropump described in Embodiment 1; a heat dissipation flow channel is formed between the parallel piezoelectric micropump and the device to be dissipated. Each outflow structure 31 of the parallel piezoelectric micropump faces the device to be dissipated; the device generating heat is effectively dissipated by pumping a low-temperature heat exchange medium into the heat dissipation flow channel through the parallel piezoelectric micropump.

Claims

1. An acoustically enhanced driven parallel piezoelectric micropump, comprising an input layer (10), a support structure (40) and an output layer (30) stacked in sequence; characterized in that: It also includes a plurality of actuators disposed in the support structure (40); the actuators are arranged in a straight line array or in a matrix; an input chamber (100) connected to the input layer (10) is formed between the actuators; and a plurality of output chambers (200) independent of each other are formed between the actuators and the output layer (30); the actuators are used to pump fluids through their own vibrations; The input layer (10) is provided with a plurality of inlet structures (11); the positions of the inlet structures (11) are staggered with the through-flow structures on the actuator; the acoustic wave vibration of the vibrating actuator in the input chamber (100) forms a standing wave; the positions of the plurality of antinode points of the standing wave are aligned with the positions of the respective inlet structures (11); the output layer (30) is provided with a plurality of outlet structures (31); the positions of the outlet structures (31) are aligned with the through-flow structures on the actuator; Each actuator corresponds to a pump flow unit; the operating vibration frequency of the actuator f a is 18kHz~22kHz; the length of a single pump flow unit is controlled at 3 mm~4 mm; the operating vibration frequency of the actuator The acoustic resonance frequency of the input chamber (100) The following relationship is satisfied: 0.8f ≤ f a ≤ 1.2f.

2. The acoustically enhanced parallel piezoelectric micropump according to claim 1, characterized in that: The positions of the inlet structures (11) are aligned with the connection between two adjacent actuators, or with the edges of the actuators at the ends; The center distance P between adjacent inlet structures (11), the length L and width of the input chamber (100) The following relations are satisfied: ； in, is the zero point of the Bessel function.

3. The acoustically enhanced parallel piezoelectric micropump according to claim 1, characterized in that: The acoustic resonance frequency of the input chamber (100) The acoustic resonance frequency of the input chamber (100) is 18kHz to 22kHz. By inputting the length L and width of the chamber (100) adjust.

4. The acoustically enhanced parallel piezoelectric micropump according to claim 1, characterized in that: The actuator comprises two actuating units arranged side by side; the actuating units comprise a vibration plate (20), a flexible sealing structure (51) and a vibration element; the edges of the vibration plate (20) are respectively a fixed edge, a movable edge and two swinging edges; the fixed edges of the vibration plates (20) in the two actuating units are respectively fixed on two opposite side surfaces inside a support structure (40); a flow gap (300) is formed between the movable edges of the vibration plates (20) in the two actuating units; the swinging edge of the vibration plate (20) and the inside of the support structure (40) are connected by a flexible sealing structure (51); and the initial width of the flow gap (300) is controlled to be between 1 μm and 10 μm.

5. The acoustically enhanced parallel piezoelectric micropump according to claim 4, characterized in that: A groove structure is provided on the side of the vibration plate (20) close to the output chamber (200); the groove structure has a width of less than 60 μm and a depth less than or equal to 50% of the thickness of the vibration plate (20); and the distance between the groove structure and the flow gap (300) is less than or equal to 30 μm.

6. The acoustically enhanced parallel piezoelectric micropump according to claim 1, characterized in that: The actuator comprises four actuator units arranged in a circle; the actuator units comprise a vibration plate (20) and a vibration element; a side edge of each vibration plate (20) away from the center position of the actuator is fixed to the inner cavity of a support structure (40); the remaining edges of the different vibration plates (20) form a flow gap (300); and the initial width of the flow gap (300) is controlled to be between 1 μm and 10 μm.

7. The acoustically enhanced parallel piezoelectric micropump according to claim 6, characterized in that: The shapes of the four actuating units are either of the following two schemes: Solution 1: The four actuating units are all triangular in shape; the flow gaps (300) between the four actuating units are X-shaped; Solution 2: Two of the actuating units are in the shape of a triangle, and the other two actuating units are in the shape of a trapezoid; the two actuating units in the shape of a triangle and the two actuating units in the shape of a trapezoid are alternately arranged in sequence around the center of the actuator.

8. A pump air driving method, characterized in that: Using an acoustically enhanced driven parallel piezoelectric micropump as described in any one of claims 5 to 7; characterized in that: the pumping gas driving method includes a forward pumping gas method and a reverse self-cleaning method; The forward pumping method comprises: applying excitation signals of the same frequency and the same phase to different vibration elements (21) in the same actuator; each actuating unit in the same actuator vibrates synchronously in the same direction, driving the airflow to enter from the inlet structure (11), pass through the input chamber (100), the flow gap (300) and the output chamber (200), and then be output from the outlet structure (31); The reverse self-cleaning method comprises: applying different excitation signals to different vibration elements (21) in the same actuator, causing each actuating unit in the same actuator to vibrate asynchronously, causing the gas in the piezoelectric micropump to flow in the reverse direction during part or all of the operation time, with the gas entering from the outflow structure (31) and being output from the inflow structure (11).

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