Piezoelectric Servovalve Drive for High-Frequency Large-Flow Control
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Solution Overview
Problem
Conventional servovalves face challenges in handling large fluid flows effectively at high operation frequencies while maintaining a compact design and minimizing vulnerability to contamination, damage, and leakage.
Innovation Solution
A servovalve design incorporating a piezoelectric drive assembly with a piezoelectric actuator and torsion springs at the valve spool ends, which replaces the traditional motor-driven first stage, allowing for more direct and responsive control of fluid flow and reducing the system's size and susceptibility to damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If jet pipe servovalves are used to handle large fluid flows, then the valve is less sensitive to contamination, but the valve becomes larger and more complex with additional external joints and pipes
Solution Approach 1:
The patent merges the jet pipe fluid supply system with the valve body by providing fluid supply passages directly within the valve body structure. The jet pipe is positioned to receive fluid through these internal passages, eliminating the need for external fluid supply pipes and joints. This integration maintains the contamination-resistant benefits of jet pipe design while reducing structural complexity and vulnerability to external damage.
2Volume of moving object
If flapper type servovalves are used for large flows, then the valve structure is compact, but flow forces act in the direction of flapper movement forcing the motor to overcome these forces
Solution Approach 1:
The patent replaces the motor-driven flapper mechanism with a jet pipe system that uses fluid dynamic forces. Instead of a motor overcoming flow forces to move a flapper, the fluid jet itself creates the control forces by impinging on the spool. This substitution eliminates the need for a motor in the first stage and removes the problem of motors having to overcome large flow forces, while maintaining a compact structure.
3Stability of the object's composition
If clevis-like metering valves are used for large flows, then the flow forces are balanced and centered, but the valve needs to be bigger due to bigger orifices required for larger flows
Solution Approach 1:
The patent replaces the mechanical clevis structure with a jet pipe system that achieves flow force balance through fluid dynamics. The jet pipe directs fluid at an angle to create a reaction force that centers the spool, eliminating the need for large balanced orifices and mechanical balancing structures. This approach maintains force balance while enabling a more compact valve design suitable for large flows.
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 piezoelectric drive assembly enables the servovalve to operate at higher frequencies, provide greater force, and maintain a compact, less vulnerable design, enhancing its ability to manage large fluid flows and improve responsiveness.
Implementation Method 1
A servovalve design incorporating a piezoelectric drive assembly with a piezoelectric actuator
Implementation Method 2
torsion springs at the valve spool ends
Data Source
Figure 1a~1b
Figure 1c~2
Figure 3
AI summary
A servovalve comprising: a fluid transfer valve assembly comprising a supply port and a control port; a moveable valve spool (4) arranged to regulate flow of fluid from the supply port to the control port in response to a control signal; and a drive assembly configured to axially move the valve spool relative to the fluid transfer assembly in response to the control signal to regulate the fluid flow; wherein the drive assembly comprises a piezoelectric actuator (7, 8) configured to vary the flow of fluid to respective ends of the valve spool in response to the control signal.