Dual-Flapper Servo Valve Assembly for Low-Leakage Pressure Control
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Solution Overview
Problem
Conventional single stage servo valves suffer from inefficiencies due to inherent leakage and the need for oversized fuel pumps to compensate for pressure losses, limiting their suitability for many applications.
Innovation Solution
The design incorporates two flappers, each driven by a respective torque motor, positioned between the nozzles to eliminate leakage in the neutral position and reduce the displacement required for pressure control, thereby eliminating the need for oversized fuel pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single flapper is used in a conventional single stage servo valve, then the structure is simple, but inherent leakage occurs and oversized fuel pumps are required to compensate for pressure losses
Solution Approach 1:
The single flapper is segmented into two separate flappers (first flapper and second flapper), each controlling one nozzle independently. This segmentation eliminates the inherent leakage problem by allowing each flapper to precisely control its associated nozzle without requiring the other side to be closed, thereby reducing pressure losses and eliminating the need for oversized fuel pumps.
2Stability of the object's composition
If a single flapper is positioned equidistant from both nozzles in neutral position, then the valve is balanced, but leakage cannot be eliminated
Solution Approach 1:
The control function is segmented from a single flapper into two independent flappers, each associated with one nozzle. In the neutral position, both flappers remain equidistant from their respective nozzles maintaining balance, but can independently close their nozzles to eliminate leakage without requiring the other side to be closed.
Solution Approach 2:
Each flapper acts as an intermediary element between the torque motor and its associated nozzle, providing precise control. The flappers mediate the control action by positioning themselves relative to the nozzles to either allow or block fluid flow, enabling reliable leakage control while maintaining valve balance.
3Stress or pressure
If oversized fuel pumps are used to compensate for pressure losses, then sufficient pressure is maintained, but system efficiency decreases
Solution Approach 1:
By segmenting the control into two independent flapper-nozzle pairs, the system eliminates the pressure losses associated with single flapper design. This allows the use of appropriately sized fuel pumps that maintain sufficient pressure without the excess capacity needed in conventional designs, thereby improving system efficiency.
4Power
If large flapper displacement is required for pressure control, then the valve can handle low power applications, but the response time increases
Solution Approach 1:
The segmentation into two independent flapper-nozzle control paths allows for more efficient pressure control with reduced flapper displacement. Each flapper controls one side of the valve independently, enabling faster response times while maintaining the power handling capability through the combined effect of both control paths.
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 configuration enhances the efficiency of single stage servo valves by minimizing leakage and reducing the flapper displacement needed for pressure control, allowing them to be used in applications previously reserved for two stage servo valves.
Implementation Method 1
a first torque motor located on a first side of the valve body and a second torque motor located on a second side of the valve body opposite the first side
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A single stage servo valve assembly comprising: a drive assembly (1000); and a valve body assembly (2000), the valve body assembly defining a valve body (2001) extending along a valve body axis (X) between a first valve body end and a second valve body end; a supply port (101), a control port (102) and a return port (103) formed through the valve body each defining a respective fluid flow channel, having a fluid flow axis, providing fluid communication between an interior of the valve body and an exterior of the valve body, wherein the drive assembly operates to control the flow of fluid between the supply port, the control port and the return port, via the interior of the valve body, in response to an electric command signal; wherein a first nozzle (201A) is located in the valve body between the supply port and the control port and a second nozzle (201B) is located between the return port and the control port, the first nozzle defining a first fluid flow path from the supply port to the control port and the second nozzle defining a second fluid flow path between the control port and the return port; wherein the drive assembly comprises a flapper means (501, 510) extending in a direction essentially perpendicular to the valve body axis from a first end in connection with the drive assembly to a second end that extends into a space (S) between the first nozzle and the second nozzle, the second end being moveable by means of the drive means, relative to the nozzles; the assembly characterised in that the drive means comprises a first motor (600A) located on a first side of the valve body and a second motor (600B) located on a second side of the valve body opposite the first side as defined with respect to the valve body axis, and wherein the flapper means comprises a first elongate flapper (501) extending along a first flapper axis YA from a first end (502) in driving engagement with the first motor to a second end (503) in the space (S), and a second elongate flapper (510) extending from a first end (511) in driving engagement with the second motor along a second flapper axis YB to a second end (512) in the space (S), wherein the second end of the first flapper is located adjacent the first nozzle and the second end of the second flapper is located adjacent the second nozzle.