Dual-Spool Servo Valve for Precise Flow Control With Lower Tolerance Demands
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Solution Overview
Problem
Existing servo valves require precise tolerances and can suffer from wear and inaccuracies due to the use of single spools, especially when utilizing piezoelectric actuators, leading to hysteresis and reduced accuracy in fluid control.
Innovation Solution
A dual-spool servo valve system with independent piezoelectric actuators for each spool, allowing for precise control of fluid flow through multiple metering edges, reducing the need for a pilot stage and enhancing accuracy by enabling independent translation of the spools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single spool with multiple lands is used, then the valve can control fluid flow through multiple ports, but the manufacturing precision requirement increases and wear-related reliability decreases
Solution Approach 1:
The patent divides the single spool into multiple separate spools (first spool and second spool), each with fewer lands. This segmentation reduces the manufacturing precision requirement for each individual spool while maintaining the overall fluid flow control capability through coordinated operation of multiple spools.
2Reliability
If a single spool with multiple lands is used, then the valve can block fluid flow at equilibrium, but wear over time reduces reliability
Solution Approach 1:
By segmenting the spool into multiple independent spools, the wear on each spool is reduced compared to a single spool with multiple lands. Each spool has fewer contact points and lower stress, extending service life while maintaining the ability to block fluid flow when both spools are at equilibrium position.
3Measurement precision
If piezoelectric actuators are used for precise control, then the valve achieves accurate fluid flow control, but hysteresis reduces measurement precision
Solution Approach 1:
The patent applies different control strategies to different spools. The first spool is controlled by a piezoelectric actuator for precise positioning, while the second spool uses a different actuation method. This local differentiation optimizes overall system performance by compensating for piezoelectric hysteresis through coordinated control of multiple spools with different actuation characteristics.
4Measurement precision
If a pilot stage is added for actuation, then the valve achieves precise control, but the device complexity increases
Solution Approach 1:
The patent extracts and eliminates the pilot stage from the traditional servo valve design. Instead of using a pilot stage to control main spool movement, the invention directly actuates the spools using piezoelectric actuators and other direct actuation methods, simplifying the overall device structure while maintaining precise fluid flow control capability.
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 dual-spool system improves accuracy and reduces wear-related issues, providing more precise control over fluid flow and simplifying the manufacturing process while minimizing the number of high-tolerance components needed.
Implementation Method 1
a first piezoelectric actuator operatively connected to the first spool for translating the first spool in response to a voltage applied thereto
Data Source
AI summary
A servo valve comprises a first spool extending along a first spool axis, a second spool extending along a second spool axis, a first piezoelectric actuator, and a second piezoelectric actuator. The first piezoelectric actuator is operatively connected to the first spool for translating the first spool in response to a voltage applied thereto. The second piezoelectric actuator is operatively connected to the second spool for translating the second spool in response to a voltage applied thereto.