Two-Stage Servo Valve Spool Layout for Compact Flow Control
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Solution Overview
Problem
Conventional two-stage servo valves are large, bulky, and costly due to the need for precise machining and assembly, which is not suitable for applications with size, weight, and cost constraints, such as in aircraft and aerospace industries.
Innovation Solution
A simplified two-stage servo valve design with a spool having only two control edges and a housing with three ports, reducing the complexity and cost of manufacturing and assembly, while maintaining effective fluid flow control through optimized spool movement within the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional two-stage servo valve design is used, then fluid flow control precision is maintained, but device size and weight increase significantly
Solution Approach 1:
The patent merges the supply channel and first control channel into a single integrated passage structure within the spool body. The spool features a unified internal flow path that combines multiple fluid control functions, eliminating the need for separate supply and control channels while maintaining precise fluid flow control. This integration reduces the overall valve size and weight without compromising control precision.
2Measurement precision
If conventional two-stage servo valve design is used, then fluid flow control precision is maintained, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines multiple channel functions into a single integrated spool design. The spool body contains merged supply and control channels that work together as one unified structure, reducing the number of separate components and machining operations required. This integration simplifies manufacturing while preserving the precision fluid flow control characteristics.
Solution Approach 2:
The spool component is designed to perform multiple functions simultaneously - it serves as both a supply channel conductor and a control channel regulator through its integrated internal passages. This multi-functionality reduces the overall component count and manufacturing complexity while maintaining precise fluid flow control capabilities.
3Reliability
If conventional two-stage servo valve design is used, then reliable fluid flow control is achieved, but assembly time and cost increase
Solution Approach 1:
The patent integrates the supply and control channels into a single molded or machined spool component. This merged structure eliminates the need for separate assembly steps for installing individual supply and control channel components, significantly reducing assembly time while maintaining the reliable fluid flow control through the integrated passage design.
4Measurement precision
If spool with multiple control edges is used, then fluid flow control precision is improved, but manufacturing cost and time increase
Solution Approach 1:
The patent merges the functions of multiple control edges into a single integrated spool geometry with unified internal passages. The merged channel design achieves precise fluid flow control through its integrated structure without requiring multiple separate control edges, thereby simplifying manufacturing while maintaining control precision.
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 results in a smaller, lighter, and less expensive servo valve that is quicker to manufacture and assemble, with improved dynamic behavior and reduced resistance, enabling reliable and efficient operation.
Implementation Method 1
a spool axially moveable within an axial cavity defined within the housing to control flow of fluid between the plurality of ports according to the axial position of the spool
Implementation Method 2
a first stage with a motor e.g. an electrical or electromagnetic force motor or torque motor is controlling a moveable member
Data Source
AI summary
A two-stage servo valve comprising a first, drive stage (11) and a second fluid transfer stage, the fluid transfer stage comprising a housing (140) having a plurality of ports (70, 80, 90) and a spool (50) axially moveable within an axial cavity (142) defined within the housing to control flow of fluid between the plurality of ports according to the axial position of the spool, wherein the drive stage is configured to cause axial movement of the spool; wherein the housing comprises three ports, a first port being a supply port fluidly connected to a second port, being a control port, via a supply channel (sc) and a first control channel (cc1) via the spool cavity, and a third port being a return port fluidly connected to the control port via a return channel (rc) and a second control channel (cc2) via the spool cavity, and wherein the spool comprises a middle portion (53) and first and second end portions (51a, 51b), a first opening (52) defined between a first edge (K1) of the middle portion and the first end portion and a second opening (54) defined between a second edge (L1) of the middle portion and the second end portion, the first and second openings (52, 54) being sized such that in a neutral position, the first opening (52) does not overlap both the supply channel and the first control channel and the first edge K1 is positioned to prevent fluid flow between the supply channel and the first control channel and the second opening (54) does not overlap both the return channel and the second control channel and the second edge L1 is positioned to prevent fluid flow between the second control channel and the return channel; in a first axial position, the first edge K1 is positioned such that the first opening (52) overlaps at least a portion of both the supply channel and the first control channel to allow fluid flow between the supply channel and the first control channel, and the second opening (54) does not overlap both the return channel and the second control channel and the second edge L1 is positioned to prevent fluid flow between the second control channel and the return channel; and in a second axial position, the second edge L1 is positioned such that the second opening (54) overlaps at least a portion of both the return channel and the second control channel to allow fluid flow between the return channel and the second control channel, and the first opening (52) does not overlap both the supply channel and the first control channel and the first edge K1 is positioned to prevent fluid flow between the supply channel and the first control channel.