Acoustic enhancement driven parallel piezoelectric micropump and driving method thereof

Abstract

The invention discloses an acoustically enhanced driven parallel piezoelectric micropump and a driving method thereof. The input layer, the supporting structure and the output layer are sequentially arranged in a stacked mode. The device is characterized by further comprising a plurality of actuators arranged in the supporting structure. The actuators are arranged in a linear array or a matrix. And an input cavity which is connected into a whole is formed between each actuator and the input layer. And a plurality of mutually independent output cavities are formed between each actuator and the output layer. The actuator is used for pumping fluid through self vibration. The input layer is provided with a plurality of inflow structures staggered with the through-flow structures on the actuator. The output layer is provided with a plurality of outflow structures aligned with the through-flow structures on the actuator. The multiple pump flow units are connected in parallel, acoustic vibration is coupled with mechanical vibration, the multiple flow inlet structures are arranged at the multiple antinode points of acoustic resonance, flowing of fluid is further enhanced, and the air pumping efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of piezoelectric fluid micropumps, and in particular relates to an acoustically enhanced driven parallel piezoelectric micropump and a driving method thereof. Background Art

[0002] Driven by Generative AI (GAI) technology, the heat problem associated with smartphones is difficult to solve by relying solely on passive cooling technology. The piezoelectric active air-cooling / liquid-cooling solution prepared using micro-electromechanical technology (MEMS) can solve this problem well. Among them, the liquid cooling pump is far less universal than the air cooling solution due to the risk of liquid leakage.

[0003] Traditional active air cooling devices are limited in their application in mobile phones due to their large thickness and high power consumption. In addition, traditional fans have some other disadvantages, such as high noise, which affects the user experience; mechanical parts are easy to wear, resulting in a short life; and it is difficult to achieve precise air volume control, and it is impossible to dynamically adjust according to the actual heat dissipation needs of the device. Traditional piezoelectric micropump structures are mostly fixed on all sides, and the central membrane layer has a high residual stress, which reduces its vibration.

[0004] Traditional piezoelectric micropumps still have certain limitations in terms of heat dissipation efficiency and stability. For example, in order to achieve higher performance output, it is often necessary to connect multiple heat dissipation units in parallel, but simple parallel connection can easily lead to fluid turbulence inside the parallel chamber, thus failing to achieve the desired performance improvement. In order to further improve the performance of piezoelectric micropumps, it is possible to improve their driving efficiency through acoustic enhancement. Acoustically enhanced driven parallel piezoelectric micropumps use the coupling of sound waves and mechanical vibrations to significantly improve the flow efficiency of the fluid, thereby achieving more efficient heat dissipation.

[0005] By using acoustic coupling to mechanical vibration, the flow of fluid is enhanced through acoustic vibration and the pumping efficiency is improved. The Helmholtz resonant cavity is a classic acoustic resonance structure, and its resonant frequency can be precisely controlled by adjusting the cross-sectional area and volume of the cavity. The principle of the Helmholtz resonant cavity is applied to the design of the piezoelectric micropump. By adjusting the width and height of the input chamber, the acoustic resonance frequency inside the chamber is matched with the mechanical resonance frequency of the piezoelectric micropump, thereby achieving the coupled resonance of acoustic vibration and mechanical vibration, and enhancing the flow efficiency of the fluid by 30%-50%. Its simple and reliable design and optimized control capabilities give it a competitive advantage in the market, and it is expected to become the mainstream development direction of micropump technology in the future. Summary of the invention

[0006] The purpose of the present invention is to propose an acoustically enhanced driven parallel piezoelectric micropump to achieve more efficient heat dissipation in applications such as electronic device heat dissipation. By using the principle of the Helmholtz resonant cavity, higher performance output is achieved through acoustic coupling of mechanical vibrations. Combined with micro-nano processing technology, a lower power consumption and more miniaturized device structure can be achieved. Through a specific structure and driving method, the present invention can simultaneously achieve the functions of forward pump flow heat dissipation and reverse self-cleaning under the excitation of different frequencies, thereby providing continuous and stable heat dissipation output performance.

[0007] In a first aspect, the present invention provides an acoustically enhanced driven parallel piezoelectric micropump, comprising an input layer, a support structure and an output layer stacked in sequence; characterized in that: it also comprises a plurality of actuators arranged in the support structure. Each actuator is arranged in a straight line array or in a matrix. An input chamber connected to the input layer is formed between each actuator. Multiple output chambers independent of each other are formed between each actuator and the output layer. The actuator is used to pump fluid by self-vibration.

[0008] The input layer is provided with a plurality of inlet structures. The positions of the inlet structures are staggered with the through-flow structures on the actuator. The acoustic wave vibration of the vibrating actuator in the input chamber 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. The output layer is provided with a plurality of outflow structures corresponding to the respective output chambers. The positions of the outflow structures are aligned with the through-flow structures on the actuator.

[0009] Preferably, the positions of the inlet structures are aligned with the connection between two adjacent actuators, or with the edges of the actuators at the ends.

[0010] The center distance P of adjacent inlet structures, the length L and width of the input chamber The following relations are satisfied:

[0011]

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

[0013] Preferably, the operating vibration frequency of the actuator The acoustic resonance frequency of the input chamber The following relationship is satisfied: 0.8f ≤f a ≤ 1.2f.

[0014] Preferably, the acoustic resonance frequency of the input chamber is 18kHz~22kHz; input the acoustic resonance frequency of the chamber By inputting the length L and width of the chamber Adjustment.

[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 comprises two actuating units arranged side by side. The actuating units comprise a vibration plate, a flexible sealing structure and a vibration element. The edges of the vibration plate are respectively a fixed edge, a movable edge and two swinging edges. The fixed edges of the vibration plates in the two actuating units are respectively fixed on two opposite sides inside the supporting structure. A flow gap is formed between the movable edges of the vibration plates in the two actuating units. The swinging edge of the vibration plate is connected to the inside of the supporting structure by a flexible sealing structure.

[0017] Preferably, a groove structure is provided on the side of the vibration 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 vibration plate; the distance between the groove structure and the flow gap is less than or equal to 30 μm.

[0018] Preferably, the actuator comprises four actuator units arranged in a circle. The actuator units comprise a vibration plate and a vibration element. The edge of each vibration plate away from the center of the actuator is fixed to the inner cavity of the support structure. The remaining edges of different vibration plates form flow gaps.

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

[0020] Solution 1: The four actuating units are all triangular in shape, and the flow gaps between the four actuating units are X-shaped.

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

[0022] In a second aspect, the present invention provides a pumping gas driving method, which uses the aforementioned acoustically enhanced driven parallel piezoelectric micropump; characterized in that: the pumping gas driving method includes a forward pumping gas method and a reverse self-cleaning method;

[0023] The forward pumping method comprises: applying excitation signals of the same frequency and the same phase to different vibration elements in the same actuator; each actuating unit in the same actuator vibrates synchronously in the same direction, driving the air flow to enter from the air inlet structure, pass through the input chamber, the flow gap and the output chamber, and then be output 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, the actuating units in the same actuator vibrate asynchronously, the gas in the piezoelectric micropump flows in the reverse direction during part or all of the operation time, the air flow enters from the air outlet and is output from the air inlet.

[0025] The present invention has the following beneficial effects:

[0026] 1. The present invention realizes the coupling of acoustic vibration with mechanical vibration by connecting multiple pump flow units in parallel, and arranges multiple flow inlet structures at multiple antinodes and node points of acoustic resonance, so as to further enhance the flow of fluid and improve the pumping efficiency.

[0027] 2. The present invention can adjust the length and width of the input chamber without changing the structure of each pumping unit by regulating the number and arrangement of parallel pumping units, thereby realizing the regulation of the resonant frequency of the input chamber, and then controlling the mechanical vibration frequency of the actuator at a relatively low level (about 20kHz) while making the mechanical vibration frequency close to the resonant frequency of the input chamber; therefore, the present invention can reduce mechanical losses as much as possible while generating coupled vibrations, thereby further improving the energy conversion efficiency.

[0028] 4. The present invention helps to relieve the pressure generated in the output chamber during the pumping process by opening a groove structure on the side of the vibration plate close to the flow gap, thereby reducing the resistance encountered by the vibration plate during the vibration process, increasing the amplitude of the actuator, and further improving the pumping performance.

[0029] 5. Compared with the traditional piezoelectric pump with fixed periphery, the actuator in the present invention adopts the vibration form of reciprocating swing up and down, which reduces the influence of residual stress on the piezoelectric device. At the same time, the present invention can realize the function of reverse self-cleaning by applying different excitation signals to the vibration element on the vibration plate, which is more suitable as a heat dissipation element of electronic devices and has a wide range of application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0031] Figure 2 Schematic diagram of standing wave distribution generated by acoustic vibration in parallel input chambers in Example 1 of the present invention.

[0032] Figure 3 Comparison chart of analytical solution and simulation solution of Helmholtz resonance width and acoustic vibration frequency.

[0033] Figure 4 Schematic diagram of the structure of the actuator in Example 1 of the present invention.

[0034] Figure 5 This is a schematic diagram of the working mode of the forward pump flow in Example 1 of the present invention.

[0035] Figure 6 This is a schematic diagram of the working mode of reverse self-cleaning in Example 1 of the present invention.

[0036] Figure 7 This is an exploded diagram of a device in which four pump flow units are connected in parallel in Example 2 of the present invention.

[0037] Figure 8 This is an exploded diagram of a device in which eight pump flow units are connected in parallel in Example 2 of the present invention.

[0038] Fig. 9 Schematic diagram of the structure of the actuator in Example 3 of the present invention.

[0039] Fig.10 Schematic diagram of the structure of the actuator in Example 4 of the present invention.

[0040] Fig.11 Schematic diagram of the structure of the actuator in Example 5 of the present invention.

[0041] Fig.12 Schematic diagram of the structure of the actuator in Example 6 of the present invention. DETAILED DESCRIPTION

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

[0043] Example 1

[0044] like Figure 1 As shown, an acoustically enhanced driven parallel piezoelectric micropump comprises an input layer 10, a support structure 40, an output layer 30 stacked in sequence, and a plurality of actuators arranged in a straight line. 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 apart from the input layer 10. The partition divides the inner cavity range of the support structure 40 into a plurality of pump flow areas arranged side by side. The number of actuators is equal to the number of pump flow areas and corresponds one to one.

[0045] Each actuator is arranged in a corresponding pump flow area. In the initial state, the top surface of the actuator is flush with the top surface of the partition. An input chamber 100 connected as one is formed between each actuator and the input layer 10. Multiple output chambers 200 separated by partitions 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 structure in the actuator by its own vibration, so as to realize continuous pumping of the fluid of the pump flow unit. The flow structure is located in the middle of the actuator.

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

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

[0049] For a Helmholtz cavity, the resonant frequency is It can be expressed as:

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

[0051] When the vibration frequency of the actuator Acoustic resonant frequency When the acoustic vibration and the mechanical vibration are close, they will couple and resonate, thereby enhancing the amplitude of the mechanical vibration and improving the performance; in this embodiment Take 0.8f~1.2f.

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

[0053]

[0054] Since the height is more than an order of magnitude different from the length and width, it is ignored and the focus is on the length L of the input chamber. A shorter input chamber length L will result in a higher acoustic resonance frequency. Therefore, if you want to couple acoustic vibration with mechanical vibration, you can reduce the acoustic resonance frequency Or increase the mechanical vibration frequency Two aspects.

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

[0056] Therefore, although high-frequency driven mechanical vibration can also couple acoustic vibration, higher frequency will bring greater mechanical loss and reduce energy conversion efficiency. It is 18kHz~22kHz.

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

[0058] like Figure 5 As shown, when the integral input chamber 100 formed by the parallel connection of the pump flow units meets the acoustic resonance condition, the acoustic vibration generated by it 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 wave vibration and the flow efficiency is enhanced. Therefore, the present invention sets the inlet structure 11 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 the wavelength of the acoustic standing wave. The standing wave wavelength can be simply obtained by the acoustic resonance frequency, that is,

[0060]

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

[0062] Therefore, the center distance P of two adjacent inlet structures 11, the length L of the input chamber 100, and the width The following relationship is satisfied:

[0063]

[0064]

[0065] Combining the above equations, we can get that, ideally, the length L and width of the input chamber 100 are , the optimal relationship between the center distances P of adjacent inlet structures 11 is as follows:

[0066]

[0067] At the same time, since the center distance P of the inlet structure 11 is consistent with the length of the pump flow unit, and the number n of the pump flow units along the length direction is an integer, n=L / P is a positive integer.

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

[0069] In this embodiment, the multiple output chambers 200 are independent of each other, and their main purpose is to ensure the stable performance output of a single pump flow unit. Compared with the connected input chamber 100, the output chamber outflow structure 30 is limited by the position limit (it must be opposite to the flow gap 300), so the connected output chamber may cause the same sound wave vibration to inhibit the fluid flow inside the output chamber 200. Further, the flow gap 300 is set at the node of the standing wave formed by the connected input chamber 100 to prevent the sound 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 pump flow units in parallel can be greater than two, such as 4, 8 or more, but at least the length of the input chamber 100 after the array must be no less than 2000 μm, and the vibration frequency of the actuator must be It is 18kHz~22kHz.

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

[0072] In this embodiment, the actuator using a double swing oscillator structure includes two actuating units arranged left and right. The opposite sides of the two actuating units are fixedly connected to a set of opposite side surfaces in the corresponding pump flow area of ​​the support structure 40. The arrangement direction of the two actuating units is consistent with the arrangement direction of the two pump flow units.

[0073] As Figure 1 and Figure 4 As shown, a flow gap 300 is formed between adjacent sides of the two actuating units. The actuating unit includes a vibration plate 20, a flexible sealing structure 51 and a vibration element. The four edges of the vibration plate 20 are a fixed edge, a movable edge and two swinging edges. The two swinging edges are one set of opposite edges of the vibration plate 20; the fixed edge and the movable edge are the other set of opposite edges of the vibration plate 20. The fixed edge of the vibration plate 20 is fixed to the inner side surface of the corresponding pump flow area. The two swinging edges of the vibration plate 20 are close to the corresponding inner side walls on the support structure 40 and leave a flow gap 300.

[0074] A flexible sealing structure 51 is connected between the two swinging edges of the vibration plate 20 and the corresponding side walls or partitions in the support structure 40. One side of the flexible sealing structure 51 is bonded and fixed to the swinging edge of the vibration plate 20, and the other side is fixed to the side wall or partition in the support structure 40. The flexible sealing structure 51 closes the gap between the swinging edge of the vibration plate 20 and the inner side wall of the support structure 40, and realizes the sealing between the two swinging edges of the vibration plate 20 and the inner side surface of the pump flow area, so that the fluid only flows through the flow gap 300 during the operation of the piezoelectric micropump. The flexible sealing structure 51 can be stretched and deformed as the vibration plate 20 swings up and down, so it will not affect the swinging reciprocating vibration of the vibration plate 20.

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

[0076] In this embodiment, the pump flow unit is square, and its 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 compound, and germanium compound.

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

[0078] One side of all the vibration elements is grounded, and the other side is connected to an independent power supply control interface, so that all the vibration elements in this embodiment can be controlled independently. For each pump flow unit, by passing driving signals of different frequencies or the same frequency but different phases to the vibration elements in the two actuating units, asynchronous vibration of the two actuating units can be achieved.

[0079] In some other embodiments, one of the vibration elements in the same actuator is called the first vibration element, and the other vibration element is called the second vibration element; the first vibration elements in all actuators are controlled in parallel; the second vibration elements in all actuators are controlled in parallel; thereby, while independently controlling the two vibration elements in the same actuator, different actuators are controlled synchronously; on the one hand, reverse pumping air 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 gap 300 is controlled between 1 μm and 10 μm; when the actuator is in a stationary state, the flow 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 gap 300 or only a small amount of fluid can pass through (which can be ignored).

[0081] The flow gap 300 and the two independent vibration plates 20 are obtained by etching and dividing a complete layer plate structure in the middle. The two vibration elements can be produced by dividing a whole large piezoelectric material after etching the flow gap 300, or they can be formed by sputtering at two symmetrical positions of the actuator. The vibration element uses piezoelectric material, 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 the shape of an elongated strip, and the length direction is parallel to the length direction of the through-flow gap 300; the inlet structure 11 can be a long strip through-groove structure, or a queue through-hole structure formed by a plurality of through-holes arranged 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 outflow structure 31 can be a long strip through-slot structure or a queue through-hole structure formed by a plurality of through-holes arranged in sequence. The width of the output position of the outflow 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: two different excitation signals are applied to the two vibration elements of the same pump flow unit respectively; in this embodiment, there is a certain difference in the frequency of the two different excitation signals, which is set to 50Hz in this embodiment, so that the two actuating units vibrate asynchronously, and the width of the flow gap 300 between the two vibration plates 20 changes greatly; at this time, the fluid inside the piezoelectric micropump will flow in the reverse direction different from the forward pump flow, so that the airflow enters from the outflow structure 31, passes through the output chamber 200, the flow gap 300 and the input chamber 100, and is output from the inflow structure 11. This is to achieve that while the first vibration element 22 vibrates toward the input layer 10, the second vibration element 23 vibrates toward the output layer 30, and vice versa.

[0101] In this embodiment, reverse self-cleaning can blow away the dust blocked at the inlet structure 11 during the forward pump flow, thereby playing a role in cleaning and restoring the flow rate drop of the piezoelectric micropump caused by the blockage of the inlet structure 11, so that the piezoelectric micropump can continue to blow air to dissipate heat to the external heating structure efficiently.

[0102] Example 2

[0103] A parallel piezoelectric micropump driven by acoustic enhancement, the difference between this embodiment and embodiment 1 is that the partition in the support structure 40 is a grid structure, so that a plurality of pump flow areas arranged in a matrix of multiple rows and columns are formed in the support structure 40. An actuator is provided in each pump flow area, forming a plurality of pump flow units arranged in a matrix.

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

[0105] Example 3

[0106] A parallel piezoelectric micropump driven by acoustic enhancement, the difference between this embodiment and embodiment 1 is that: the structure of the vibration plate 20 is different; a rectangular groove 24A is opened on the side of the vibration plate 20 close to the output chamber 200 and close to the flow gap 300. The rectangular groove 24A is formed by etching. The rectangular groove 24A is not directly connected to the flow gap 300.

[0107] like Fig. 9As shown, the presence of the rectangular groove 24A on the two vibration plates 20 forms an additional chamber at the bottom of the two vibration plates 20, which helps to relieve the pressure generated by the output chamber 200 during the pumping process, thereby making the two vibration plates 20 less subject to resistance during the vibration process and increasing the amplitude of the actuator. In this embodiment, the width of the rectangular groove 24A is less than 60μm, and the depth is less than or equal to 50% of the thickness of the vibration plate 20; the distance between the rectangular groove 24A and the flow gap 300 is not more than 30μm.

[0108] Example 4

[0109] A parallel piezoelectric micropump driven by acoustic enhancement, the difference between this embodiment and embodiment 1 is that: the structure of the vibration plate 20 is different; an arc groove 24B is opened on the side of the vibration plate 20 close to the output chamber 200 and close to the flow gap 300. The arc groove 24B is formed by etching. The arc groove 24B is not directly connected to the flow gap 300.

[0110] like Fig.10 As shown, the presence of the arc-shaped groove 24B on the two vibration plates 20 forms an additional chamber at the bottom of the two vibration plates 20, which helps to relieve the pressure generated by the output chamber 200 during the pumping process, thereby making the two vibration plates 20 less subject to resistance during the vibration process and increasing the amplitude of the actuator. In this embodiment, the width of the arc-shaped groove 24B is less than 60μm, and the depth is less than or equal to 50% of the thickness of the vibration plate 20; the distance between the arc-shaped groove 24B and the flow gap 300 is not more than 30μm.

[0111] Example 5

[0112] A parallel piezoelectric micropump driven by acoustic enhancement, the difference between this embodiment and embodiment 1 is that the structure of the actuator is different.

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

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

[0115] Compared with the structure of Example 1, the actuator structure provided in this embodiment avoids the gap between the dual vibration plates 20 and the support structure 40, so there is no need to use polymer for sealing, which reduces 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 chamber volume changes more greatly, and the driving ability is further improved.

[0116] Example 6

[0117] A parallel piezoelectric micropump driven by acoustic enhancement, the difference between this embodiment and embodiment 1 is that the structure of the actuator is different.

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

[0119] In this embodiment, the flexible sealing structure 51 is not provided in the actuator unit. Compared with the structure of Example 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 polymer for sealing, which reduces 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 its chamber volume changes more greatly, and the driving ability has been further improved. 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 of the structure along the trapezoidal direction is more obvious, and it is more suitable for the scenario of parallel use in this direction.

[0120] Example 7

[0121] A piezoelectric heat dissipation system includes the parallel piezoelectric micropump described in Example 1; a heat dissipation channel is formed between the parallel piezoelectric micropump and the device to be cooled. Each outflow structure 31 of the parallel piezoelectric micropump is directed toward the device to be cooled; the parallel piezoelectric micropump pumps pump a low-temperature heat exchange medium to the heat dissipation channel, thereby effectively cooling the device to be heated.

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 flow-through structures on the actuator; the acoustic wave vibrations of the vibrating actuator in the input chamber (100) form standing waves; the positions of the plurality of antinode points of the standing waves 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 flow-through structures on the actuator.

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 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.

4. The acoustically enhanced parallel piezoelectric micropump according to claim 3, 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.

5. The acoustically enhanced parallel piezoelectric micropump according to claim 1, characterized in that: Each actuator corresponds to a pump flow unit; the length of the pump flow unit is 3 mm to 4 mm.

6. 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; and the swinging edge of the vibration plate (20) and the inside of the support structure (40) are connected via a flexible sealing structure (51).

7. The acoustically enhanced parallel piezoelectric micropump according to claim 1, 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.

8. 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); and the remaining edges of the different vibration plates (20) form flow gaps (300).

9. The acoustically enhanced parallel piezoelectric micropump according to claim 8, 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.

10. A pump air driving method, characterized in that: Using an acoustically enhanced driven parallel piezoelectric micropump as described in any one of claims 6 to 9; 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 airflow to enter from the air intake structure (11), pass through the input chamber (100), the flow gap (300) and the output chamber (200), and then be output from the air 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 gas outlet (31) and being output from the gas inlet (11).

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