A longitudinal vibration sandwich transducer assembly, a rectifying pump body and a valveless piezoelectric micropump

Abstract

This invention discloses a longitudinal vibration sandwich transducer assembly, a rectifier pump body, and a valveless piezoelectric micropump, belonging to the field of piezoelectric micropump technology. The main body of the device includes a longitudinal vibration sandwich transducer, a vibrating plate, and a multi-stage right-angle flow-restricting pump body; the core lies in the longitudinal vibration sandwich transducer employing a screw axial pre-tightening structure, utilizing the d-axis properties of piezoelectric ceramics... 33 The operating mode generates high-power-density longitudinal vibration, which drives the vibrating plate to produce bending vibration through the energy-concentrating effect of the amplitude transformer. The multi-stage right-angle flow-resistance pump body innovatively designs a symmetrical flow channel composed of multiple right-angle flow-resistance components. Utilizing the vortex shedding effect of the right-angle structure, it constructs highly efficient asymmetric flow resistance characteristics, thereby achieving high-frequency cavity vibration while deeply suppressing backflow losses. This invention overcomes the shortcomings of traditional patch-type piezoelectric micropumps, such as low energy utilization, easy fatigue of the adhesive layer, and insufficient rectification efficiency of conventional valveless pumps, significantly improving the output flow stability and long-term operational reliability of the device under high-frequency driving conditions.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric micropump technology, specifically to a longitudinal vibration sandwich transducer assembly with high energy conversion efficiency, a multi-stage right-angle choke pump body, and a valveless piezoelectric micropump device comprising the above-mentioned assembly and the multi-stage right-angle choke pump body. Background Technology

[0002] Piezoelectric micropump technology utilizes the inverse piezoelectric effect of piezoelectric ceramics to excite vibrations in the pump chamber or elastomer, driving liquid flow along the channel through periodic pressure changes, thereby achieving liquid delivery and quantitative control. Currently, most mature piezoelectric micropumps are driven by directly bonding or attaching piezoelectric ceramic sheets to the pump chamber structure. Piezoelectric ceramics typically operate in the d31 mode with low electromechanical coupling efficiency, resulting in relatively low energy utilization. Furthermore, the strength of the adhesive layer between the piezoelectric ceramic and the pump chamber limits the pump's maximum flow rate, while the fatigue life of the adhesive layer also restricts the pump's long-term stable operation and reliability.

[0003] On the other hand, valveless pump design avoids the mechanical structures such as diaphragm valves and check valves found in traditional micro pumps, significantly reducing wear and jamming risks and improving system reliability and service life. However, existing valveless pumps suffer from low flow channel rectification efficiency and severe backflow, resulting in poor energy utilization and operational stability. Common Z-shaped cavity bottoms or inlet / outlet wedge groove structures mainly rely on the continuous gradual change of the flow channel cross-sectional area to generate flow resistance differences, but in high-frequency oscillating flow fields, the asymmetry they generate is limited, and the backflow suppression effect is not ideal. Chinese patent CN201921820057.0 discloses a "sandwich-type valveless piezoelectric pump," which uses a U-shaped frame to clamp piezoelectric wafers to form a bending vibration mode, achieving rectification through the geometric asymmetry of the inlet and outlet channels. However, this scheme still uses bending vibration as the driving mode, resulting in low electromechanical conversion efficiency, and the rectification structure depends on the shape of the inlet and outlet, failing to significantly improve rectification efficiency from the internal flow channel design of the pump cavity, and the overall energy utilization of the system still needs to be improved.

[0004] Therefore, there is an urgent need for a valveless piezoelectric micropump solution that can synergistically improve energy utilization and operational stability from both the driving source and flow channel design aspects. Summary of the Invention

[0005] This invention aims to solve the above-mentioned problems and provide a valveless piezoelectric micropump solution with high energy utilization, stable operation, and excellent backflow suppression. This solution first innovates independently from two core components: one is to provide a d-type screw-based axial preload... 33First, a longitudinal vibration sandwich transducer assembly is used to address the efficiency and stability issues at the drive end. Second, a symmetrically distributed multi-stage right-angle flow-blocking fluid is designed within the multi-stage right-angle flow-blocking pump body to address the problem of low backflow suppression. Finally, these two components are combined to form a complete micro-pump device, achieving a significant improvement in overall performance through the synergistic effect between the components.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A longitudinal vibration sandwich transducer assembly for a valveless piezoelectric micropump includes: a rear end cover (1-1), a flange (1-2), longitudinal vibration piezoelectric ceramic plates (1-3) and electrode plates (1-4) stacked alternately along the axial direction, and an amplitude transformer (1-5); the rear end cover (1-1), flange (1-2), longitudinal vibration piezoelectric ceramic plates (1-3), and electrode plates (1-4) are fixed together with the large end of the amplitude transformer (1-5) by an axially arranged fastening screw (1-6) to achieve axial pre-tightening; the small end of the amplitude transformer (1-5) is used to connect to and drive the vibrating plate (2).

[0007] A multi-stage right-angle flow-blocking pump body includes: a pump chamber (3-1), an inlet (3-2), an outlet (3-3), and a right-angle flow-blocking fluid (3-4) respectively connected to the pump chamber, wherein the axes of the inlet (3-2) and the outlet (3-3) coincide; the right-angle flow-blocking fluid (3-4) is protrudingly disposed on the bottom surface of the pump chamber (3-1), and the right-angle flow-blocking fluid is configured to be symmetrically distributed about the axes of the inlet and the outlet, and the right-angle flow-blocking fluids work together to form an asymmetric flow channel with different resistance to forward and reverse flow on the bottom surface of the pump chamber.

[0008] A valveless piezoelectric micropump based on a longitudinal vibration sandwich transducer includes: the aforementioned longitudinal vibration sandwich transducer assembly; the aforementioned multi-stage right-angle flow-blocking pump body; and a vibrating plate (2); one side center of the vibrating plate (2) is fixedly connected to the small end of the amplitude transformer (1-5), and the other side covers and seals the pump cavity opening of the pump body.

[0009] In a preferred embodiment, the right-angle blocking fluid (3-4) includes a right-angle blocking fluid near the liquid inlet at the edge (3-4a), a right-angle blocking fluid near the liquid inlet at the center (3-4b), a right-angle blocking fluid near the liquid outlet at the edge (3-4c), and a right-angle blocking fluid near the liquid outlet at the center (3-4d), and the right-angle blocking fluids are symmetrically distributed along the axis of the liquid inlet (3-2).

[0010] In a preferred embodiment, there are four longitudinally vibrating piezoelectric ceramic sheets (1-3), all of which are polarized along the thickness direction and the polarization directions of adjacent sheets are opposite. There are also four electrode sheets (1-4).

[0011] In a preferred embodiment, the obstructing fluid is a right-angle obstructing fluid. Further, the symmetrically distributed right-angle obstructing fluids form at least two W-shaped flow channels on the bottom surface of the pump chamber.

[0012] In a preferred embodiment, the pump chamber (3-1) has an octagonal cross-section.

[0013] In a preferred embodiment, the inner diameter of the inlet (3-2) is larger than the inner diameter of the outlet (3-3); a conical drainage channel (3-6) is provided on the inner side of the outlet (3-3).

[0014] The present invention also provides a control method for the above-mentioned valveless piezoelectric micropump, comprising: using AC voltage excitation to cause the longitudinally vibrating piezoelectric ceramic plate (1-3) to generate the inverse piezoelectric effect, and its mechanical deformation is amplified by the amplitude transformer (1-5) to drive the vibrating plate (2) to reciprocate; subsequently, the vibration causes periodic fluctuations in the pressure inside the octagonal pump chamber (3-1), and the fluid rectification is achieved by combining the asymmetric flow resistance difference constructed by the right-angle flow resistance fluid (3-4) inside the chamber, and finally the stable unidirectional pumping of the liquid is achieved through the accumulation of high-frequency energy.

[0015] Compared with the prior art, the present invention has the following significant advantages: (1) In this invention, the longitudinal vibration sandwich transducer assembly adopts a screw axial pre-tightening structure. The screw axial pre-tightening ensures the mechanical integrity of the transducer under high frequency and high power conditions, effectively avoids the performance degradation caused by long-term high frequency vibration, and significantly extends the service life of the device. The piezoelectric ceramic works in the d33 mode with higher electromechanical coupling efficiency, and has high energy density output and long-term working stability. The variable cross-section structure of the amplitude rod can realize the concentration of vibration energy, significantly improve the amplitude and velocity of the small end, and thus effectively improve the output flow of the device. The screw-fastened sandwich structure can effectively avoid various problems caused by insufficient adhesive layer strength and limited fatigue life of traditional patch piezoelectric micropumps.

[0016] (2) The pump body of the multi-stage right-angle flow-blocking pump of the present invention, through the coupling of the octagonal pump cavity and the symmetrical W-shaped flow channel, combined with the stepped flow field formed by multiple right-angle flow-blocking fluids, constructs a flow resistance asymmetry that is more efficient than the traditional Z-shaped or wedge-shaped structure. Its advantage lies in the fact that the vortex shedding effect of the right-angle structure greatly suppresses the reverse backflow, and at the same time, combined with the nozzle effect of the asymmetric inlet and outlet, it significantly improves the rectification efficiency, output pressure and flow stability of the valveless piezoelectric pump.

[0017] (3) When the two components are combined, the system produces a synergistic effect of "1+1>2". The longitudinal vibration sandwich transducer assembly provides an efficient and stable high-energy-density drive source; the rectifier pump assembly realizes efficient directional conversion of fluid kinetic energy. The high-speed oscillating jet generated by the longitudinal vibration sandwich transducer fully excites the vortex shedding effect of the right-angle obstructed fluid, causing the kinetic energy on the return path to be strongly dissipated, while the forward flow passes through with low resistance; at the same time, the reduction of the return flow significantly reduces the proportion of negative work done by the vibrating plate, making the driving energy more effectively converted into net flow. This synergistic effect significantly improves the hydraulic efficiency of the system, and the output flow and pressure are significantly increased. Meanwhile, the axisymmetric distribution of the components in the pump chamber ensures the radial balance of the force on the vibrating plate, and combined with the high dynamic stiffness of the sandwich structure, it effectively resists the disturbance caused by load fluctuations, ensuring the high linearity of the flow output and long-term working stability of the micro pump under complex working conditions. Attached Figure Description

[0018] Figure 1 This is a cross-sectional view of the multi-stage right-angle choke fluid valveless piezoelectric micropump device based on a longitudinal vibration sandwich transducer as described in this invention. Figure 2 This is a three-dimensional structural schematic diagram of a multi-stage right-angle choke fluid valveless piezoelectric micropump device based on a longitudinal vibration sandwich transducer; Figure 3 This is a structural schematic diagram of a multi-stage right-angle flow-restricting pump body; Figure 4 This is an isometric view of a multi-stage right-angle flow-restricting pump body; Figure 5 This is a schematic diagram of the initial state of the piezoelectric micropump device when the longitudinal vibration sandwich transducer is in a free state; Figure 6 This is a cross-sectional view of the micropump with a longitudinally vibrating sandwich transducer in the contracted state, and a schematic diagram of the flow field inside the pump. Figure 6 A is a diagram showing the transducer in its contracted state. Figure 6 B is a schematic diagram of the flow field inside the pump; Figure 7 This is a cross-sectional view of the micropump with a longitudinally vibrating sandwich transducer in the elongated state, and a schematic diagram of the flow field inside the pump. Figure 7 A is a diagram showing the state of transducer elongation. Figure 7 B is a schematic diagram of the flow field inside the pump;

[0019] 1-Longitudinal vibration sandwich transducer; 2-Vibrating plate; 3-Multi-stage right-angle flow-blocking pump body; 1-1-Rear end cover; 1-2-Flange; 1-3-Longitudinal vibration piezoelectric ceramic plate; 1-4-Electrode plate; 1-5-Amplitude rod; 1-6-Fastening screw; 3-1-Octagonal pump chamber; 3-2-Inlet; 3-3-Outlet; 3-4-Right-angle flow-blocking; 3-5-W-type flow channel; 3-6-Conical drainage channel. Detailed Implementation

[0020] Please see Figure 1 and Figure 2 A multi-stage right-angle flow-blocking valveless piezoelectric micropump device based on a longitudinal vibration sandwich transducer is integrated into three parts: a longitudinal vibration sandwich transducer 1, a vibrating plate 2, and a multi-stage right-angle flow-blocking pump body 3. The longitudinal vibration sandwich transducer 1 includes: a rear end cover 1-1, a flange 1-2, longitudinal vibration piezoelectric ceramic plates 1-3 and electrode plates 1-4 stacked alternately along the axial direction, and an amplitude transformer 1-5. The rear end cover 1-1, flange 1-2, longitudinal vibration piezoelectric ceramic plates 1-3, and electrode plates 1-4 are fixed to the large end of the amplitude transformer 1-5 by an axially arranged fastening screw 1-6, achieving axial pre-tightening. The amplitude transformer 1-5 is a block with a gradually tapering cross-section, and its small end connects to and drives the vibrating plate 2. There are four electrode plates 1-4 and four longitudinal vibration piezoelectric ceramic plates 1-3. All longitudinal vibration piezoelectric ceramic plates (1-3) are polarized along the thickness direction, and the polarization directions of adjacent plates are opposite.

[0021] Please see Figure 3 and Figure 4 The multi-stage right-angle flow-blocking pump body 3 of this embodiment of the invention is provided with an octagonal pump cavity 3-1, an inlet 3-2, an outlet 3-3, and a right-angle flow-blocking fluid 3-4 respectively communicating with the pump cavity 3-1. The axes of the inlet 3-2 and the outlet 3-3 coincide. The right-angle flow-blocking fluid 3-4 protrudes from the bottom surface of the pump cavity 3-1, specifically including a right-angle flow-blocking fluid 3-4a near the inlet at the edge, a right-angle flow-blocking fluid 3-4b near the inlet at the center, a right-angle flow-blocking fluid 3-4c near the outlet at the edge, and a right-angle flow-blocking fluid 3-4d near the outlet at the center. The right-angle flow-blocking fluids are symmetrically distributed along the axis of the inlet 3-2. The symmetrically distributed right-angle flow-blocking fluids together form two symmetrically distributed W-shaped flow channels 3-5. The right-angle flow-blocking fluid 3-4 is integrally formed with the pump cavity 3-1. The height of the right-angle flow-blocking fluid is lower than the height of the side wall of the octagonal pump cavity 3-1. The outer diameter of the inlet 3-2 is larger than the outer diameter of the outlet 3-3, the inner diameter of the inlet 3-2 is larger than the inner diameter of the outlet 3-3, and a conical drainage channel 3-6 is provided on the inner side of the outlet 3-3.

[0022] The center of one side of the vibrating plate 2 is fixedly connected to the small end of the amplitude rod 1-5 by laser welding, and the pump cavity opening of the multi-stage right-angle flow-blocking pump body is covered and sealed by laser welding on the other side.

[0023] Please see Figure 5 When the longitudinal vibration sandwich transducer 1 is in a free state, such as Figure 5 As shown.

[0024] Please see Figure 6 When the longitudinal vibration sandwich transducer 1 contracts axially, as Figure 6As shown in Figure A, the vibrating plate 2 deforms towards the outside of the pump chamber. At this time, the volume of the octagonal pump chamber 3-1 increases instantaneously, generating negative pressure and guiding a large amount of external liquid to flow in from the inlet 3-2 (corresponding to the dark solid arrow in the figure). Simultaneously, the right-angled flow barrier 3-4 located in the pump chamber forms a physical barrier against the liquid attempting to be drawn back from the outlet 3-3 (corresponding to the white hollow arrow in the figure), thereby ensuring that the chamber can efficiently "fully load" the fluid during the liquid suction phase. Figure 6 As shown in B.

[0025] Please see Figure 7 When the longitudinal vibration sandwich transducer 1 elongates axially, such as Figure 7 As shown in Figure A, the driving vibrator 2 deforms towards the inside of the pump chamber. At this time, the volume inside the octagonal pump chamber 3-1 rapidly shrinks, generating high pressure, forcing the liquid inside the chamber to smoothly spray out from the outlet 3-3 along the W-shaped flow channel 3-5 (corresponding to the dark solid arrow at the top of the figure). Meanwhile, the fluid attempting to escape back to the inlet 3-2 (corresponding to the white hollow arrow at the bottom of the figure) violently impacts the edge of the multi-stage right-angle flow barrier 3-4, inducing a violent vortex shedding effect and generating extremely high reverse flow resistance, like a "fluid roadblock" locking the return path, achieving powerful unidirectional pumping, such as... Figure 7 As shown in B.

[0026] The working process of the valveless piezoelectric micropump is as follows: First, the longitudinally vibrating piezoelectric ceramic plate (1-3) is excited by AC voltage to generate the inverse piezoelectric effect. Its mechanical deformation is amplified by the amplitude transformer 1-5 and drives the vibrating plate 2 to vibrate reciprocally. Subsequently, the vibration causes periodic fluctuations in the pressure inside the octagonal pump cavity 3-1. Combined with the asymmetric flow resistance difference constructed by the right-angle flow resistance 3-4 inside the cavity, the fluid is rectified. Finally, the stable unidirectional pumping of the liquid is achieved through the accumulation of high-frequency energy.

[0027] The working mechanism of the device is described as follows: 1. Power conversion stage: Electrical energy is converted into mechanical energy. When an external drive signal is applied to electrode 1-4, the four longitudinally vibrating piezoelectric ceramic plates 1-3 located between flange 1-2 and amplitude transformer 1-5, under the action of the drive voltage, utilize the highly efficient electromechanical coupling of the d-type piezoelectric ceramic plates. 33 The operating mode generates axial extension and contraction vibration. The fastening screws 1-6 and the rear end cap 1-1 work together to provide preload to the ceramic plate, ensuring mechanical stability under high-frequency vibration and preventing energy dissipation. This high-frequency micro-vibration, after entering the amplitude transformer 1-5, utilizes the variable cross-section structure to generate an energy-concentrating amplification effect, significantly increasing the amplitude and velocity at the end of the amplitude transformer.

[0028] 2. Cavity Deformation Stage: Negative Pressure Liquid Absorption and High Pressure Liquid Discharge The end of the amplitude transformer is fixedly connected to the vibrating plate 2, transmitting the longitudinal mechanical wave to the octagonal pump cavity 3-1 of the multi-stage right-angle flow-blocking pump body 3. Suction stroke: When the transducer contracts, causing the vibrating plate to deform away from the pump cavity, the volume inside the pump cavity increases instantaneously, generating negative pressure. Liquid mainly enters the pump cavity through the inlet 3-2. At this time, the right-angle flow-blocking fluid 3-4 utilizes geometric resistance to generate a large reverse resistance, suppressing the backflow of liquid from the outlet 3-3. Discharge stroke: When the transducer extends, causing the vibrating plate to deform towards the inside of the pump cavity, the volume inside the pump cavity decreases, generating high pressure and driving the fluid outward.

[0029] 3. Rectification and suppression stage: Asymmetric flow resistance enables unidirectional pumping. This device integrates a multi-stage right-angle flow barrier 3-4 and a W-shaped flow channel 3-5 within an octagonal pump chamber 3-1, creating a significant asymmetric flow resistance characteristic: during the discharge stroke, the fluid flows smoothly along the W-shaped flow channel 3-5 towards the outlet 3-3, while fluid attempting to flow backward towards the inlet 3-2 will flow into a "funnel" composed of a central right-angle flow barrier or an edge right-angle flow barrier and the inner wall of the pump chamber, inducing a severe vortex shedding effect and momentum dissipation, resulting in high local resistance; combined with the nozzle effect generated by the conical drainage channel 3-6 inside the outlet 3-3, this mechanism achieves an extremely high flow resistance difference during the suction and discharge cycle, thereby ensuring efficient unidirectional pumping of fluid in the ultrasonic frequency band.

Claims

1. A longitudinal sandwich transducer assembly for a valveless piezoelectric micropump, characterized by include: The rear end cover (1-1), flange (1-2), longitudinally vibrating piezoelectric ceramic plates (1-3) and electrode plates (1-4) are stacked alternately along the axial direction, and an amplitude transformer (1-5); the rear end cover (1-1), flange (1-2), longitudinally vibrating piezoelectric ceramic plates (1-3), and electrode plates (1-4) are fixed to the large end of the amplitude transformer (1-5) by an axially set fastening screw (1-6) to achieve axial pre-tightening; the small end of the amplitude transformer (1-5) is connected to and drives the vibrating plate (2).

2. The longitudinal vibration sandwich transducer assembly of claim 1, wherein, The number of longitudinally vibrating piezoelectric ceramic sheets (1-3) is four. All longitudinally vibrating piezoelectric ceramic sheets (1-3) are polarized along the thickness direction, and the polarization directions of adjacent sheets are opposite.

3. A multi-stage right angle blocking pump body, characterized by, include: The pump chamber (3-1) is connected to an inlet (3-2), an outlet (3-3), and a right-angle flow barrier (3-4). The axes of the inlet (3-2) and the outlet (3-3) coincide. The right-angle flow barrier (3-4) protrudes from the bottom surface of the pump chamber (3-1). The right-angle flow barrier is configured to be symmetrically distributed about the axes of the inlet and the outlet. The right-angle flow barrier works together to form an asymmetric flow channel with different resistance to forward and reverse flow on the bottom surface of the pump chamber.

4. The pump body of claim 3, wherein The right-angle resistance fluid (3-4) includes a right-angle resistance fluid near the liquid inlet at the edge (3-4a), a right-angle resistance fluid near the liquid inlet at the center (3-4b), a right-angle resistance fluid near the liquid outlet at the edge (3-4c), and a right-angle resistance fluid near the liquid outlet at the center (3-4d). The right-angle resistance fluids are symmetrically distributed along the axis of the liquid inlet (3-2).

5. The multi-stage right angle flow blocking pump body of claim 3, wherein, The symmetrically distributed right-angled flow barriers form at least two W-shaped flow channels (3-5) on the bottom surface of the pump chamber.

6. The multi-stage right angle flow blocking pump body of claim 3, wherein, The pump chamber (3-1) has an octagonal cross-section.

7. The multi-stage right angle pump body of claim 3, wherein, The inner diameter of the liquid inlet (3-2) is larger than the inner diameter of the liquid outlet (3-3).

8. The multi-stage right-angle flow-restricting pump body according to claim 6, characterized in that, The inner side of the liquid outlet (3-3) is provided with a conical drainage channel (3-6).

9. A valveless piezoelectric micropump based on a longitudinal vibration sandwich transducer, characterized in that, include: The longitudinal vibration sandwich transducer assembly according to claim 1 or 2; the multi-stage right-angle flow-blocking pump body according to any one of claims 3 to 7; and the vibrating plate (2); one side center of the vibrating plate (2) is fixedly connected to the small end of the amplitude rod (1-5), and the other side covers and seals the pump cavity opening of the multi-stage right-angle flow-blocking pump body.

10. A control method for a valveless piezoelectric micropump as described in claim 9, characterized in that, The longitudinally vibrating piezoelectric ceramic sheet (1-3) is excited by AC voltage to generate the inverse piezoelectric effect. Its mechanical deformation is amplified by the amplitude transformer (1-5) and drives the vibrating sheet (2) to vibrate back and forth. Subsequently, the vibration causes periodic fluctuations in the pressure inside the octagonal pump chamber (3-1). Combined with the asymmetric flow resistance difference constructed by the right-angle flow barrier (3-4) inside the chamber, the fluid is rectified. Finally, the stable unidirectional pumping of the liquid is achieved through the accumulation of high-frequency energy.

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