Spool Servo Valve Layout for Precise Flow Control With Low Leakage
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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 critical.
Innovation Solution
A servo valve design featuring a movable member with specific cross-sectional areas and surfaces forming a channel within the valve housing, actuated by solenoids and biased by a spring, allowing for precise control of fluid flow through multiple ports with minimal leakage and reduced calibration needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a flapper and nozzle mechanism is used to control fluid flow, 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 system and replaces it with a spool valve mechanism. The spool valve directly controls fluid flow through its position in the valve body, eliminating the need for flapper-deflector-nozzle calibration while maintaining precise control capability.
Solution Approach 2:
The patent replaces the mechanical flapper-nozzle control system with a spool valve mechanical system. The spool valve uses a sliding spool mechanism within a valve body to directly regulate fluid flow, substituting the complex flapper-deflection mechanism with a simpler linear positioning system that reduces calibration requirements.
2Measurement precision
If a flapper and nozzle mechanism is used to control fluid flow, then precise control of actuator movement is achieved, but leakage occurs
Solution Approach 1:
The patent removes the flapper and nozzle components that are prone to leakage and replaces them with a spool valve design. The spool valve creates sealed fluid passages through precision machining of the valve body and spool, eliminating the jet injection mechanism that can leak.
Solution Approach 2:
The patent employs hydraulic sealing principles within the spool valve design, where precision-fitted surfaces and sealing rings create reliable fluid barriers. The valve body and spool are designed with mating surfaces that maintain hydraulic seals under pressure, preventing leakage while controlling fluid flow.
3Reliability
If a spool valve with multiple sealing sections is used, then leakage is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple sealing functions into a single integrated spool component. The spool includes first and second cavity sealing sections and nozzle obstructing sections all in one piece, which can be manufactured using precision machining or additive manufacturing techniques, reducing assembly complexity while maintaining multiple sealing surfaces.
Solution Approach 2:
The spool valve component performs multiple functions simultaneously: it seals the first and second cavities, obstructs nozzles when needed, and controls fluid flow between ports. This multi-functional design consolidates what would otherwise require multiple separate components into a single versatile element.
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 design enables precise and reliable control of fluid flow with reduced leakage and simplified construction, allowing for more efficient and accurate actuator movement 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
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AI summary
A servo valve (10) comprises a valve housing (12), a cavity (16) formed in the valve housing (12) defining an axis (X) and an axially moveable member (18) disposed in the cavity (16). At least one actuator (22a, 22c) is configured to axially move the member (18) within the cavity (16) and a spring (26) is arranged between first and second axial ends of the valve housing (12a, 12b). A channel (20) is formed within the cavity (16) and a plurality of ports (48a, 48b, 48c) each forming a fluid passage through the valve housing (12) in fluid communication with a spool (80) and with the channel (20). The plurality of ports (48a, 48b, 48c) comprise first and second nozzles (50a, 50c) with nozzle openings (52a, 52c), wherein in a first axial position of the member (18) the first nozzle opening (52a) is at least substantially obstructed, and in a second axial position of the member (18) the second nozzle opening (52c) is at least substantially obstructed, the member (18) controlling fluid between the spool (80) and the channel (20).