Piezoelectric Servovalve Spool Control for High-Flow Response

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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, being less vulnerable to contamination, damage, and leakage.

Innovation Solution

A servovalve design incorporating a piezoelectric actuator to regulate fluid flow to the valve spool, with a drive stage assembly that includes a piezoelectric element and rod, allowing axial movement in response to control signals, and a housing with orifices connected via fluid channels, along with torsion springs for each spool end, enabling efficient fluid management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional flapper type servovalves are used to handle large fluid flows, then large valve orifice areas are required, but flow force acts in the direction of flapper movement forcing the motor to overcome the flow forces

Engineering Contradiction:

Improvefluid flow rateVSAvoidflow force on motor

Core Design Contradiction:

Quantity of substanceVSForce

Solution Approach 1:

The patent replaces the conventional flapper-type mechanical drive system with a piezoelectric actuator that directly drives the valve spool. This substitution eliminates the flapper mechanism and its associated flow forces acting on the motor, while maintaining the ability to control large fluid flows through direct spool actuation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the actuation mechanism from electromagnetic motor-driven flapper to piezoelectric-driven spool. This parameter change in the drive system allows direct control of the valve spool position without encountering flow forces that oppose motor operation in flapper-type systems.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If jet pipe servovalves are used to reduce contamination sensitivity, then the valve is less sensitive to contamination, but the valve becomes larger and more complex with external supply pipes

Engineering Contradiction:

Improvecontamination resistanceVSAvoidvalve structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the supply port and control port into a single integrated fluid transfer valve assembly. The piezoelectric actuator is positioned between these ports and directly actuates the valve spool within the same housing, eliminating the need for external supply pipes and separate jet pipe components found in conventional designs.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent nests the piezoelectric actuator and valve spool within a compact housing that integrates the fluid transfer pathways. The actuator is positioned between the supply and control ports with fluid channels providing pathways around it, creating a nested, space-efficient configuration that reduces overall valve size and complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Quantity of substance

If larger valve orifices are used to handle larger flows, then flow capacity increases, but the valve size increases

Engineering Contradiction:

Improvefluid flow capacityVSAvoidvalve size

Core Design Contradiction:

Quantity of substanceVSVolume of moving object

Solution Approach 1:

The patent changes the actuation mechanism to piezoelectric drive, which provides greater force output in a compact form factor. This allows the valve spool to effectively control large fluid flows through well-defined orifices without requiring oversized valve bodies or excessively large orifice areas.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

By replacing conventional motor-driven mechanisms with a piezoelectric actuator, the system achieves more efficient force transmission directly to the valve spool. This substitution enables compact valve design while maintaining the capability to handle large fluid flows through optimized spool geometry and direct actuation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 actuator-based servovalve operates at higher frequencies, provides greater force, and maintains a compact, less vulnerable design, enhancing responsiveness and reducing the risk of contamination and leakage.

Implementation Method 1

a piezoelectric actuator configured to vary the flow of fluid to respective ends of the valve spool in response to the control signal

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

with torsion springs for each spool end

Methodology Applied

Scientific EffectElastic potential energy: Spring

Data Source

PatentUS10954971B2Servovalve

Publication Date: 2021.03.23 HAMILTON SUNDSTRAND CORP

AI summary

A servovalve includes: a fluid transfer valve assembly comprising a supply port and a control port; a moveable valve spool 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. The drive assembly comprises a piezoelectric actuator configured to vary the flow of fluid to respective ends of the valve spool in response to the control signal.