Spool Servo Valve Nozzle Obstruction for Precise Flow Control
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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 nozzle obstructing sections, actuated by solenoids, and biased by a spring, allowing for precise control of fluid flow through multiple ports with O-ring seals and screen filters, enabling precise fluid communication and minimizing leakage.
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. The spool's linear movement directly modulates the opening area of fluid passages.
Solution Approach 2:
The patent replaces the mechanical flapper-nozzle system with a spool valve mechanism that uses direct mechanical displacement of the spool to control fluid flow. This substitution eliminates the complex calibration requirements of the flapper system while providing more straightforward and reliable leakage control through the spool's sealing surfaces.
2Measurement precision
If a flapper and nozzle mechanism is used to control fluid flow, 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 design. The spool valve's continuous sealing surfaces and direct fluid path control provide superior leakage resistance compared to the discrete nozzle openings and flapper positioning system.
Solution Approach 2:
The patent employs O-ring seals (flexible sealing elements) around the spool and within the valve body to create reliable sealing barriers. These elastic seals conform to the mating surfaces and maintain sealing under varying pressure conditions, preventing leakage that would occur in rigid flapper-nozzle interfaces.
3Reliability
If O-ring seals are added to minimize leakage, then reliability improves, but device complexity increases
Solution Approach 1:
The O-ring seals are designed to be installed in grooves that automatically position them during assembly. The elastic nature of the O-rings allows them to self-seal against the spool and valve body surfaces through pressure differential, eliminating the need for complex adjustment mechanisms or multiple sealing layers.
Solution Approach 2:
The patent uses standard O-ring seal designs that are homogeneous in material and geometry, allowing for simplified manufacturing and assembly. The uniform sealing approach throughout the valve body reduces the need for different sealing technologies and simplifies maintenance procedures.
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 provides precise control of fluid flow with reduced calibration needs and minimized leakage, enhancing the reliability and efficiency of fluid control 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 axial position
Implementation Method 2
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). The member (18) comprises flat surfaces (64a, 64b) parallel to the axis (X). 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 by the first flat surface (64a), and in a second axial position of the member (18) the second nozzle opening (52c) is at least substantially obstructed by the second surface (64b), the member (18) controlling fluid between the spool (80) and the channel (20).