Bleed Valve Altitude Compensating Pneumatic Actuator
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Solution Overview
Problem
Traditional start and stability bleed valves for gas turbine engines can fail to actuate in icy conditions, preventing engine starting and compressor stability control.
Innovation Solution
A bleed valve design featuring a housing with a piston, bellows, and spring that can reliably open and close based on pressure differences, ensuring operation in various conditions, including icy environments, by using a bellows or airbag with a substantial spring constant to bias the piston into the open position and a spring to bias it into the closed position, with optional active control using a pressure system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional start and stability bleed valve is used, then the valve can provide compressor bleed function, but the valve fails to actuate in icy conditions, preventing engine starting and compressor stability control
Solution Approach 1:
The patent replaces the traditional mechanical actuator with a pneumatic actuator that uses compressed air to drive the piston. This substitution eliminates the mechanical components that are susceptible to freezing in icy conditions, while the pneumatic system remains functional because compressed air is already available in the engine system and does not freeze at operating temperatures.
Solution Approach 2:
The patent introduces a pneumatic actuator that uses compressed air pressure to actuate the bleed valve. The actuator includes a piston, bellows, and spring mechanism that converts pneumatic pressure into mechanical motion to open or close the valve. This pneumatic system is immune to freezing because the compressed air is heated by the engine operation and maintains temperatures above freezing point.
2Reliability
If a pneumatic actuator is used to replace mechanical actuator, then the valve can operate in icy conditions, but the device complexity increases
Solution Approach 1:
The pneumatic actuator serves multiple functions: it acts as both the actuation mechanism and the control element, while also providing altitude compensation through the bellows mechanism. The compressed air supply, already present in the engine system for other purposes, is dual-utilized to power the actuator, eliminating the need for separate pneumatic infrastructure.
Solution Approach 2:
The bellows is nested within the actuator housing and integrates the altitude compensation function directly into the actuator structure. The spring mechanism is housed within the same assembly, creating a compact nested configuration where multiple components occupy overlapping spatial volumes, reducing overall complexity.
3Adaptability or versatility
If altitude compensation is added to the pneumatic actuator, then the valve can maintain consistent performance across different altitudes, but the device complexity increases
Solution Approach 1:
The bellows acts as a counterbalancing element that compensates for altitude effects. As external atmospheric pressure decreases with altitude, the bellows expands, maintaining constant pressure within the actuator chamber. This passive compensation mechanism automatically adjusts to altitude changes without requiring external control signals or additional active components.
Solution Approach 2:
The altitude compensation system is self-regulating and requires no external control. The bellows automatically responds to changes in external atmospheric pressure by expanding or contracting, thereby maintaining constant actuator performance across different altitudes without requiring pilot input, electronic sensors, or additional control systems.
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 valve reliably aids in engine starting and maintains compressor stability across different altitudes and operational conditions, including icy conditions, by ensuring consistent actuation and preventing compressor stall or surge.
Implementation Method 1
using a bellows or airbag with a substantial spring constant to bias the piston into the open position
Implementation Method 2
a spring to bias it into the closed position
Implementation Method 3
can reliably open and close based on pressure differences
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A valve includes a housing with a mounting portion (66), a venting portion (72), and a cap portion (76). The valve also includes a piston (60) in the housing with a shaft (86), a disc (88), and a flange (90), the piston being moveable between a closed position and an open position. The valve also includes a vessel (62) that is in contact with the cap portion and the flange wherein fluid pressure contained in the vessel biases the piston into one of the opened position and the closed position.