Conical Spool Servo Valve for Precise Flow Control
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Solution Overview
Problem
Existing servo valve designs, such as the flapper and nozzle arrangement, face challenges in achieving precise movement control, require tight tolerances, and are heavy, complex to manufacture, and limited in operational pressures and frequencies.
Innovation Solution
A servo valve assembly with a spool and conical blocking surfaces within a housing, where the spool is moveable along a central axis to vary fluid flow passages, utilizing electromagnetic forces and biasing members for precise control, and a design that simplifies construction and improves fluid flow characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a flapper and nozzle arrangement is used for servo valve control, then position control capability is achieved, but manufacturing precision requirements become extremely tight and device complexity increases
Solution Approach 1:
The patent replaces the traditional flapper and nozzle mechanical arrangement with a spool valve mechanism that uses a conical seat and movable spool. This substitution eliminates the need for tight spacing tolerances between flapper and nozzle, as the spool valve achieves precise control through axial movement along a defined axis rather than relying on precise radial positioning and small gaps.
Solution Approach 2:
The spool valve is divided into distinct functional segments: the conical seat portion that defines the flow passage geometry, the movable spool portion that controls flow area, and the housing that provides structural support. This segmentation allows each component to be manufactured and assembled with relaxed tolerances while maintaining overall control precision.
2Measurement precision
If a flapper and nozzle arrangement is used for servo valve control, then position control capability is achieved, but device weight and manufacturing complexity increase
Solution Approach 1:
The patent replaces the complex flapper and nozzle mechanical system with a simpler spool valve mechanism. The spool valve requires fewer precision-machined components and eliminates the need for delicate flapper positioning mechanisms, resulting in a lighter overall structure that maintains position control capability.
3Measurement precision
If a flapper and nozzle arrangement is used for servo valve control, then position control capability is achieved, but operational pressures and frequencies are limited
Solution Approach 1:
The spool valve design incorporates dynamic characteristics that allow faster response times compared to flapper and nozzle systems. The spool can move axially with less inertia and friction, enabling higher operational frequencies. The conical seat geometry also facilitates faster fluid flow changes, improving the valve's ability to respond to control signals at higher frequencies.
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 solution enables more precise adjustment of fluid flow, reduces weight and manufacturing complexity, and enhances operational pressures and frequencies, improving overall performance and control of the servo valve.
Implementation Method 1
the electromagnet 205 includes coils (not shown) that surround the armature 202 and a set of permanent magnets (not shown) that surround the coils. When a current is applied to the coils from the electrical input, magnetic flux acting on the ends of the armature 202 is developed. The magnetic flux will cause the armature tips 202a, 202b to be attracted to the electromagnet 205
Data Source
Figure 1
Figure 2~6
Figure 3
AI summary
The present disclosure provides a servo valve assembly (100) comprising a housing (102) defining a cylindrical cavity (140) having a central axis (C-C), and a spool (120) disposed in the cavity and co-axially aligned with the central axis. A pair of transition portions define opposing conical cavity surfaces (144, 145) each connect a respective one of first and second cylindrical cavity portions (141, 142) with a third cylindrical cavity portion (143). The spool comprises a pair of blocking members (130a, 130b) projecting radially therefrom, and each of the blocking members defines a conical blocking surface (134a, 134b) opposing a respective one of the conical cavity surfaces to define a fluid flow passage (150) therebetween. A cone angle (θa, θb) of each conical blocking surface relative to the central axis is equal to a cone angle (θa, θb) of the opposing conical cavity surface relative to the central axis. The spool is moveable along the central axis to vary a flow area of the flow passages between the conical blocking surfaces and the conical cavity surfaces. The spool further comprises a pair of guiding lands (124a, 124b) extending radially from the spool and disposed in the third cylindrical portion. The guiding lands each define a plurality of circumferentially extending guiding surfaces (127a, 127b) spaced circumferentially apart by a plurality of grooves (126a, 126b) extending axially through the guiding lands. A servo valve and method is also disclosed.