Airflow Guide Vane Control Linkage for Fail-Safe Pitch Positioning
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Solution Overview
Problem
Existing airflow guiding systems in aircraft turbine engines face issues with unknown piston and vane pitch angle positions during control kinematics breakdown, leading to increased maintenance costs and flight costs due to engine shutdowns.
Innovation Solution
A control device with an actuator and drive mechanism that ensures the control rod moves to a safety position and a known pitch angle, even in breakdown scenarios, using an over-stroke mechanism integrated between the actuation and control rods, with guide rails and bearings for reliability and accessibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control device uses a traditional hydraulic distributor to control piston movement, then the vane pitch angle can be adjusted within the nominal operating range, but the position of the piston and vane becomes unknown in case of breakdown
Solution Approach 1:
The drive mechanism is pre-configured with a safety position that the control rod automatically moves to upon breakdown. The guide rails and connecting members are designed in advance to enable this automatic positioning, ensuring the vane reaches a known safe angle without requiring active control or sensors during the failure event.
Solution Approach 2:
The drive mechanism acts as an intermediary between the hydraulic actuator and the control rod. It translates the actuator's movement into a predetermined safety position for the control rod, mediating the control signal to ensure reliable position knowledge even when the primary control system fails.
2Reliability
If the entire engine is sent to maintenance for control system failures, then the control device can be thoroughly inspected and repaired, but the hourly flight cost of the engine increases considerably
Solution Approach 1:
The control device is segmented into modular components: the actuator, the drive mechanism with guide rails, and the control rod. This segmentation allows the drive mechanism to be independently accessed and maintained without shutting down the entire engine, enabling localized repairs and reducing engine downtime.
Solution Approach 2:
The drive mechanism is designed to be self-diagnosing through its mechanical structure. The guide rails and connecting members provide inherent position feedback, and the safety position mechanism automatically corrects to a known state upon failure, allowing operators to assess the condition without complete system shutdown and perform targeted maintenance.
3Ease of repair
If the drive mechanism is integrated directly between the actuation rod and control rod, then accessibility for maintenance is improved, but the device complexity increases
Solution Approach 1:
The drive mechanism components serve multiple functions: the guide rails provide both structural support and movement guidance, the connecting members transmit force while enabling positional feedback, and the integrated assembly allows both normal operation and safety positioning. This multi-functionality reduces the need for separate components, actually simplifying the overall device while improving accessibility.
Data Source
AI summary
A device for controlling an airflow guiding system comprising:at least one vane movable in rotation about an axis of rotation between a first angle and a second angle,an actuator comprising a body inside which a piston is mounted in translation secured to an actuation rod, anda control rod comprising a downstream end connected to the axis of the vane, the actuator being configured to drive the control rod in movement between a first end position and a second end position of a nominal operating range and, in the event of breakdown of said device, to perform an over-stroke of the actuation rod into a safety position.The device comprises a drive mechanism linking an upstream end of the actuation rod to an upstream end of the control rod, opposite to the downstream end.