Inline Snap-Action Air Valve With Adjustable Closure Pressure
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Solution Overview
Problem
Existing gas turbine engine bleed valves, particularly those with poppet valve designs, experience significant pressure losses and vibration issues due to their large geometric area and tortuous flowpath, and lack adjustability in closing trigger pressure, making them inefficient during start-up and prone to recalibration challenges.
Innovation Solution
A self-actuated bleed valve assembly featuring a flow duct with a piston housing and guide tube, where a piston is biased by a spring to an open position, and a control piston and spring mechanism allow for self-actuation to adjust the valve's closure pressure, reducing pressure losses and enabling recalibration without external controls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a poppet valve design is used to achieve the required flow effective area, then the valve can meet the specified flow capacity, but the large geometric area creates a tortuous flowpath that leads to significant pressure losses
Solution Approach 1:
The valve is segmented into multiple components: a body with a streamlined bore, a piston with a smaller diameter than the bore, and a poppet valve assembly. This segmentation allows the main flow path to remain open and streamlined while the poppet valve provides precise flow control with minimal interference to the overall flow path geometry
Solution Approach 2:
The invention transitions from a traditional two-dimensional poppet valve sealing surface to a three-dimensional streamlined bore design where the piston moves axially within the bore. This dimensional change allows for a more efficient flow path that reduces turbulence and pressure losses while maintaining the required flow effective area
2Ease of manufacture
If a poppet bleed valve is mounted in a cantilever fashion, then the valve can be installed on a bulkhead or duct, but this mounting style is prone to vibration issues
Solution Approach 1:
The valve assembly merges the body, piston, spring, and poppet valve into a single integrated unit that can be mounted directly into the flow duct. This consolidation creates a more rigid structure that resists vibration better than a cantilever-mounted poppet valve while maintaining installation flexibility
Solution Approach 2:
The invention replaces the mechanical cantilever mounting system with a streamlined inline design where the valve body itself serves as the mounting structure. This substitution eliminates the vulnerable cantilever connection point and distributes mechanical stresses more evenly throughout the valve assembly
3Reliability
If a fixed closing trigger pressure is designed into the bleed valve, then the valve can operate reliably at a specific pressure point, but the valve cannot be adjusted or recalibrated throughout its life
Solution Approach 1:
The valve incorporates a dynamic adjustment mechanism where the spring preload can be modified to change the closing trigger pressure. This allows the valve to adapt to different operating requirements throughout its service life while maintaining reliable operation at the selected pressure point
Solution Approach 2:
The invention enables parameter changes by allowing adjustment of the spring compression or replacement with different spring rates. This changes the force balance equation that determines the closing trigger pressure, providing versatility without compromising the reliability of the valve's operation at its set point
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 self-actuated bleed valve assembly minimizes pressure losses through a streamlined flowpath and adjusts closure pressure, ensuring efficient operation during start-up and shutdown, reducing the need for external controllers and allowing recalibration to meet changing operational requirements.
Implementation Method 1
A spring is at least partially inside the piston and contacts the piston and biases the piston to an open position
Implementation Method 2
A control spring and a control piston are inside the piston housing. The control spring biases the control piston toward a first position that obstructs the control opening
Implementation Method 3
A fluid chamber is between the piston and an upstream end of the piston housing. A control opening extends through the upstream end of the piston housing and fluidically communicates with the flow duct and the fluid chamber
Data Source
Figure 1
Figure 2
Figure 3~3-4
AI summary
A valve assembly includes a piston housing (20) inside a flow duct (18) between an inlet and an outlet so as to form an annular flow passage (22) between the flow duct and the piston housing. The piston housing is axially aligned with a center axis of the flow duct. A piston (26) is inside the piston housing and is configured to extend downstream of the piston housing in a closed position. A spring (32) biases the piston to the open position. A fluid chamber is between the piston and an upstream end of the piston housing. A control opening extends through the upstream end of the piston housing and fluidically communicates with the flow duct and the fluid chamber. A control piston (64) and a control spring (66) are inside the piston housing. The control spring biases the control piston toward a first position that obstructs the control opening.