Bellows Valve Assembly With Pressure-Balancing Orifice
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Solution Overview
Problem
Valve assemblies in gas turbine engines face issues with parasitic leakage due to unbalanced forces on metal bellows, leading to lateral distortion and reduced service life, which increases maintenance costs and friction between moving components.
Innovation Solution
Incorporating a bellows within the valve member that includes at least one orifice to balance pressure between the control chamber and the outer volume, reducing unbalanced forces and eliminating the need for sliding seals, thereby enhancing the cyclic life and reducing friction and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If metal bellows are used to seal the control chamber at high temperatures, then thermal resistance is improved, but unbalanced forces cause lateral distortion and reduced cyclic life
Solution Approach 1:
The bellows is divided into two functional zones: an inner bellows portion sealing the control chamber and an outer bellows portion exposed to the outer volume. This segmentation allows differential pressure exposure, with the orifice balancing pressures between the two zones to eliminate lateral distortion while maintaining thermal sealing capability.
Solution Approach 2:
The orifice acts as an intermediary element that fluidly communicates the control chamber with the outer volume. It mediates pressure balance between the two bellows portions, allowing the inner portion to withstand high temperatures while the outer portion experiences balanced pressures that prevent lateral distortion.
2Reliability
If seals are used to prevent leakage, then sealing performance is improved, but friction between moving components increases
Solution Approach 1:
The invention replaces traditional sliding seals with a bellows-based sealing system. The bellows provides dynamic sealing through its expansion and contraction motion rather than sliding contact, eliminating friction between moving seal components while maintaining effective sealing of the control chamber.
3Stability of the object's composition
If pressure balance is achieved between control chamber and outer volume, then lateral distortion is eliminated, but device complexity increases
Solution Approach 1:
The inner and outer bellows portions are merged into a single integrated bellows structure that simultaneously performs multiple functions: sealing the control chamber, withstanding high temperatures, and enabling pressure balance through the orifice. This integration avoids the need for separate pressure balancing mechanisms, reducing overall device complexity.
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 significantly reduces parasitic leakage, increases the service life of the valve assembly, and lowers maintenance costs by balancing pressures and minimizing friction, resulting in a more reliable and efficient operation.
Implementation Method 1
The at least one orifice fluidly communicates the control chamber with the outer volume. The at least one orifice may allow flow of a fluid between the control chamber and the outer volume, and therefore, allow a pressure inside the control chamber to be balanced with a pressure outside the control chamber
Data Source
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AI summary
A valve assembly (100) includes a fluid flow passage (102), a valve seat (104), and an actuator assembly (120). The actuator assembly includes an actuator body (122) stationary relative to the valve seat (104) and a valve member (130) moveable relative to the valve seat between a first position in which the valve member (130) engages the valve seat (104), and a second position (P2) in which the valve member is remote from the valve seat. The valve member (130) includes at least one orifice extending therethrough. The actuator assembly (120) further includes a bellows (124) attached to the valve member (130) and to the actuator body (122). An interior surface of the bellows, the actuator body (122), and the valve member (130) define a control chamber therebetween. An exterior surface of the bellows (124) and the valve member (130) define an outer volume therebetween such that the outer volume is around the control chamber. The at least one orifice fluidly communicates the control chamber with the outer volume.