Aircraft Engine Bleed Flap Spring Preload Calibration
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Solution Overview
Problem
Existing air bleed scoop adjustment devices in aircraft engines face challenges in precise control due to direct attachment of torsion springs, leading to variability in return torques and calibration across identical valves, making it difficult to ensure consistent operation.
Innovation Solution
A torsion spring return system with an adjustable second end connected to the frame via a screwing mechanism, allowing independent adjustment of return torque and compensation for manufacturing deviations, using a connecting rod with a ball joint and guide ring for precise guidance and a tubular adjustment screw with a lock nut for calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the torsion spring is attached directly to the frame and shaft, then the structure is simple, but the adjustment of abutment positions directly impacts spring calibration causing variability in return torques
Solution Approach 1:
The patent segments the spring attachment system into three independent components: the spring itself, the abutment position adjustment mechanism, and the spring calibration adjustment mechanism. This is achieved by introducing an adjustable connection means between the spring and frame that includes separate adjustment capabilities for abutment position and spring preload, allowing each parameter to be controlled independently without affecting the other.
Solution Approach 2:
The patent introduces an intermediary adjustable connection means (comprising the connecting rod, adjustment screw, and locking mechanism) between the spring and the frame. This intermediary device acts as a mediator that decouples the relationship between abutment position and spring calibration, enabling independent adjustment of each parameter while maintaining a simple overall structure.
2Measurement precision
If abutment positions are adjusted to control flap stroke, then the stroke precision is improved, but the spring calibration varies due to direct attachment
Solution Approach 1:
The patent separates the control of flap stroke (via abutment position adjustment) from spring calibration (via preload adjustment) into independent functions. The abutment can be positioned precisely to control stroke while the spring preload is independently adjusted to maintain consistent calibration, eliminating the coupling effect that causes reliability issues.
Solution Approach 2:
The patent introduces dynamic adjustability to the spring connection system, allowing the connection point on the frame to be repositioned along the adjustment screw thread. This dynamic adjustment capability enables the system to adapt and compensate for variations, maintaining consistent spring calibration regardless of abutment position changes or manufacturing tolerances.
3Ease of manufacture
If springs are produced with standard tolerances, then manufacturing cost is reduced, but return torque variability increases across identical valves
Solution Approach 1:
The patent enables each individual valve assembly to self-adjust and self-calibrate during installation or maintenance. The adjustable connection means allows operators to compensate for spring manufacturing variations by adjusting the preload at each specific location, eliminating the need for tight spring manufacturing tolerances while maintaining consistent return torque across all valves.
Solution Approach 2:
The patent changes the adjustable parameter from spring manufacturing dimensions (which are difficult to control) to spring preload (which can be easily adjusted after assembly). By allowing adjustment of the preload parameter at the installation stage, the system compensates for manufacturing variations in spring wire diameter, coil spacing, and other dimensional parameters.
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
Enables precise and consistent calibration of air bleed devices by allowing independent adjustment of return torque and compensation for manufacturing variations, simplifying the adjustment process and maintaining precise guidance of the spring strand.
Implementation Method 1
a torsion spring, a first end of which is connected to the flap and a second end of which is connected to the frame
Implementation Method 2
a return system configured to bias the flap into a determined position around the axis and comprising a torsion spring
Implementation Method 3
said second end is connected to the frame by means for adjusting the preload of the spring by screwing when the flap is in said determined position
Data Source
AI summary
An air bleed device for an aircraft engine, including a frame and a flap able to rotate about an axis in relation to the frame, the device further including a return system configured to bias the flap in a determined position about the axis and including a torsion spring, a first end of which is connected to the flap and a second end of which is connected to the frame. The second end is connected to the frame by adjusting the preload of the spring by screwing when the flap is in the determined position.