Spool Servo Valve Architecture for Precise Flow Without Flapper Calibration
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Solution Overview
Problem
Existing servo valves in aerospace applications face challenges in precise control of fluid flow due to complex calibration requirements and potential leakage, especially in hydraulic systems where precise actuator movement is crucial.
Innovation Solution
A servo valve design featuring a moveable member with specific cross-sectional areas and surfaces that form a channel within the valve housing, allowing for precise control of fluid flow through multiple ports, combined with a spring biasing mechanism and solenoids for axial movement, enabling precise positioning and redundancy in fluid control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a flapper and nozzle mechanism is used for fluid control, then precise control of actuator movement is achieved, but complex calibration requirements and potential leakage occur
Solution Approach 1:
The patent extracts the flapper and nozzle mechanism from the servo valve system, replacing it with a spool valve design where the member directly controls fluid flow through its position in the valve body. This eliminates the complex flapper-nozzle calibration requirements while maintaining precise control capability through the spool's axial positioning.
Solution Approach 2:
The patent introduces a spool member as an intermediary element that directly interfaces with fluid passages in the valve body. This spool member, with its sealing sections and obstructing sections, serves as a mediator between the actuator and fluid flow control, eliminating the need for complex flapper-nozzle calibration while providing precise flow control through its position-dependent sealing and obstruction characteristics.
2Measurement precision
If a flapper and nozzle mechanism is used for fluid control, then precise control of actuator movement is achieved, but leakage potential increases
Solution Approach 1:
The patent removes the flapper-nozzle mechanism that is prone to leakage and replaces it with a spool valve architecture where sealing occurs through the spool member's engagement with the valve body's fluid passages. This direct sealing approach through the spool's cavity sealing sections and obstructing sections provides more reliable leakage resistance while maintaining control precision.
Solution Approach 2:
The spool member acts as an intermediary that provides direct sealing contact with the valve body's fluid passages. Its cavity sealing sections engage with the valve housing to prevent leakage, while its obstructing sections control fluid flow. This intermediary design eliminates the leakage-prone flapper-nozzle interface and provides more reliable sealing through the spool's position-dependent engagement with the valve body.
3Manufacturing precision
If multiple components are used in the servo valve, then precise fluid flow control is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent merges multiple functions into the spool member, which combines cavity sealing sections, obstructing sections, and actuator engagement features in a single component. This consolidation reduces the number of separate parts that need to be assembled and calibrated, simplifying manufacturing while maintaining precise fluid flow control through the integrated design.
Solution Approach 2:
The spool member serves multiple functions simultaneously: it seals fluid passages through its cavity sealing sections, controls fluid flow through its obstructing sections, and transmits actuator force through its engagement features. This multi-functionality reduces the overall component count and assembly complexity while maintaining the precision required for fluid flow control.
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 design provides precise and reliable control of fluid flow with reduced calibration needs and minimized leakage, enhancing the performance and reliability of hydraulic systems in aerospace applications.
Implementation Method 1
a spring arranged between first and second axial ends of the valve housing, the spring operatively connected with the member and configured to bias the member towards a neutral position
Implementation Method 2
The at least one actuator may comprise a pair of actuators arranged at opposite axial ends of the member. Each at least one actuator may be a solenoid.
Data Source
AI summary
A servo valve includes a valve housing, a cavity formed in the valve housing defining an axis (X) and an axially moveable member disposed in the cavity. At least one actuator is configured to axially move the member within the cavity and a spring is arranged between first and second axial ends of the valve housing. A channel is formed within the cavity and a plurality of ports each forming a fluid passage through the valve housing in fluid communication with a spool and with the channel. The plurality of ports comprise first and second nozzles with nozzle openings, wherein in a first axial position of the member the first nozzle opening is at least substantially obstructed, and in a second axial position of the member the second nozzle opening is at least substantially obstructed, the member controlling fluid between the spool and the channel.