Piezo Actuator Droplet Maker via Rigid Membrane
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Solution Overview
Problem
Existing methods for producing uniform droplets in the thermal spray industry face challenges with compositional non-homogeneity and limited control over droplet size, particularly at higher frequencies, due to the limitations of piezoelectric actuators in direct contact with the liquid, which restricts the production of droplets with uniform diameters and frequencies above 10 KHz.
Innovation Solution
A system comprising a solution dispenser, a fluid reservoir with a separation membrane, and a piezoelectric actuator not in direct contact with the liquid, but connected through a rigid membrane, utilizing a high-frequency electronic driver circuit with a choke inductor to generate sinusoidal perturbation waves that produce uniform droplets through capillary channels, allowing for frequencies up to 1 MHz and droplet diameters as small as 1 micrometer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If piezoelectric actuators are used in direct contact with liquid to generate droplets, then droplet generation is achieved, but frequency is limited to no higher than 10 KHz
Solution Approach 1:
A rigid membrane is introduced as an intermediary between the piezoelectric actuator and the liquid. The membrane transmits mechanical vibrations from the piezoelectric element to the liquid without requiring direct contact, enabling high-frequency operation (up to 1 MHz) while maintaining system reliability and preventing liquid contamination of the actuator.
2Productivity
If piezoelectric actuators operate at higher frequencies, then droplet generation speed increases, but droplet uniformity deteriorates
Solution Approach 1:
The system utilizes mechanically driven vibrations through the rigid membrane at controlled frequencies to generate uniform droplets. The membrane acts as an efficient vibration transmitter, allowing precise control of droplet formation at high frequencies while maintaining uniform diameter through resonant vibration modes.
Solution Approach 2:
The invention changes the operating parameters by using a rigid membrane with specific mechanical properties (stiffness, thickness) that enable high-frequency vibration transmission. This allows the system to operate at frequencies up to 1 MHz while maintaining droplet uniformity, overcoming the limitations of direct-contact piezoelectric actuators.
3Quantity of substance
If conventional droplet generation methods are used, then droplets are produced, but compositional non-homogeneity occurs in the injected solution
Solution Approach 1:
High-frequency mechanical vibrations transmitted through the rigid membrane create intense mixing and cavitation effects in the liquid, ensuring compositional homogeneity throughout the solution volume. This prevents non-uniform injection and ensures consistent coating quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables the production of uniform droplets with precise control over size and frequency, overcoming the limitations of existing technologies by allowing for higher frequency operation and smaller droplet sizes, enhancing the homogeneity and quality of surface coatings and powder generation.
Implementation Method 1
a piezoelectric actuator not in direct contact with the liquid, but connected through a rigid membrane, utilizing a high-frequency electronic driver circuit with a choke inductor to generate sinusoidal perturbation waves
Implementation Method 2
impart a disturbance and initiate capillary instability responsible to break up a single stream into uniform droplets
Implementation Method 3
connected through a rigid membrane
Implementation Method 4
adding the inductor which in the ideal case makes a resonant LC circuit with the actuator (capacitor) at the desired drive frequency
Data Source
AI summary
Systems, methods, and devices are disclosed for producing substantially uniform droplets. The system includes a fluid reservoir vessel defining a fluid reservoir, a separation membrane at one end of the fluid reservoir, at least one capillary channel at an opposite end of the fluid reservoir, a solution dispenser, and a piezo actuator in contact with a separation membrane. The separation membrane has a thickness greater than about 0.2 mm, and the solution dispenser maintains the fluid reservoir filled with fluid such that the fluid simultaneously contacts the separation membrane and the capillary channel. The solution dispenser maintains the fluid reservoir under pressure to create a fluid stream exiting the capillary. The piezo actuator is in contact with the separation membrane on a side opposite that in contact with the fluid, and the piezo actuator transfers a pressure wave through the fluid in the fluid reservoir to break up the fluid stream into uniform droplets.