Piezo Dispensing Amplifier for High-Frequency Viscous Fluid Jetting
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Solution Overview
Problem
Piezoelectric actuators used in dispensers for viscous fluids face limitations due to small displacement and reduced life expectancy when operated at high frequencies, necessitating improved actuation systems for reliable and accurate fluid jetting.
Innovation Solution
A dispensing system that incorporates a piezoelectric stack and an amplifier mechanism, where the amplifier deforms to amplify the movement of the piezoelectric stack, allowing for greater displacement of a valve element and increased fluid dispensing accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a piezoelectric stack is used as an actuator in a dispenser, then the actuator is accurate and fast reacting, but the displacement produced is very small and insufficient for proper jetting of fluids
Solution Approach 1:
A mechanical amplifier is introduced as an intermediary device between the piezoelectric stack and the valve element. The amplifier receives the small displacement from the piezoelectric stack and mechanically amplifies it to produce larger displacement at the valve element, enabling proper fluid jetting while preserving the fast response characteristics of the piezoelectric actuator
Solution Approach 2:
The mechanical amplifier changes the displacement parameter from the piezoelectric stack to a larger displacement at the valve element. By using lever arms or linkage mechanisms with different lengths, the system transforms small input displacement into larger output displacement, resolving the contradiction between small piezoelectric displacement and required jetting displacement
2Length of moving object
If the piezo stack is placed in a tension condition to increase displacement, then the displacement increases, but the life expectancy is severely shortened
Solution Approach 1:
A spring is introduced to provide a pre-compression force that counteracts the tensile loads on the piezoelectric stack. The spring maintains the stack in a compressed or neutral state during operation, preventing tension conditions that would reduce lifespan, while still allowing the stack to achieve the required displacement for fluid jetting
Solution Approach 2:
The spring provides beforehand cushioning by pre-compressing the piezoelectric stack and absorbing tensile stresses before they can damage the stack. This protective mechanism ensures the stack operates within safe stress limits, extending its operational life while maintaining sufficient displacement capability
3Productivity
If the piezoelectric stack operates at high frequency (1000 Hz continuous), then the productivity increases, but the life expectancy is severely shortened due to tension conditions
Solution Approach 1:
The spring acts as a counterweight mechanism that balances the dynamic tensile forces generated during high-frequency operation. By maintaining the piezoelectric stack in compression throughout the 1000 Hz cycling, the spring enables continuous high-speed operation without the tension-induced degradation that would otherwise limit lifespan
Solution Approach 2:
The spring provides beforehand cushioning against the repeated tensile shocks of high-frequency operation. This protective mechanism absorbs the stress cycles that would otherwise accumulate damage during 1000 Hz continuous operation, enabling high productivity while preserving the actuator's life expectancy
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
The system enhances the reliability and durability of fluid dispensing, enabling efficient and precise jetting of viscous fluids with increased lifespan and cost-effectiveness, reducing the need for complex and expensive machinery and tolerances.
Implementation Method 1
a piezoelectric stack having a distal end and being configured to expand upon application of a voltage such that the distal end is moved by a first length
Implementation Method 2
The body is configured to deform in response to a force applied to the primary surface, such that the push rod is moved in a first direction
Data Source
AI summary
A dispensing system includes a piezoelectric stack having a distal end and being configured to expand upon application of a voltage such that the distal end is moved by a first length. The system further includes an amplifier with a primary surface to contact the distal end of the stack and a secondary surface, a base configured to contact the secondary surface, and a valve assembly with an outlet orifice and valve element. The valve element is configured to move in first and second directions and is coupled with the amplifier. When the distal end is moved by a first length, a portion of the amplifier is moved by a second length that is greater than the first length, and the valve element is moved in a first direction by the second length.