Aircraft Turbomachine Airflow Vane Control With Fail-Safe Pitch
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Solution Overview
Problem
Existing airflow guidance systems in turbomachines lack reliable mechanisms to determine the position of blades in the event of a failure, leading to increased maintenance costs and potential operational risks.
Innovation Solution
A control device with an actuator and drive mechanism that ensures the control rod moves to a safety position and maintains a known blade pitch angle, even in failure scenarios, by incorporating a drive mechanism between the control rod and actuating rod, allowing overtravel to a safe setting angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blade control system is designed to reach a safety position beyond extreme positions, then safety in event of failure is improved, but device complexity increases
Solution Approach 1:
The guide casing is pre-configured with guide rails that define a predetermined path including a safety position beyond the normal operating range. The control rod is guided along this path by the guide rails, which automatically direct the control mechanism to the safety position when the actuator moves beyond extreme positions, eliminating the need for complex detection and control systems.
Solution Approach 2:
The guide casing acts as an intermediary element between the actuator and the control rod. It contains guide rails that mechanically constrain and direct the control rod's movement along a predetermined path, ensuring the control mechanism reaches the safety position without requiring complex sensing or control electronics.
2Ease of repair
If the control mechanism is made accessible for maintenance, then ease of repair is improved, but device complexity increases
Solution Approach 1:
The control mechanism is segmented into distinct components: the actuator, the control rod, and the guide casing. The guide casing is designed as a separate housing that contains the guide rails, allowing it to be removed or opened to provide direct access to the control rod and its connection to the blade, facilitating maintenance without disassembling the entire engine.
Solution Approach 2:
The guide casing serves as an intermediary structure that provides both functional guidance and maintenance access. By housing the guide rails and control rod connection within this removable or openable casing, the design enables easy access to critical components for maintenance while keeping the overall structure relatively simple.
3Measurement precision
If the piston position is always known, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The guide rails are pre-configured in the guide casing to define a predetermined movement path for the control rod. This predetermined path is directly linked to the piston's movement range, so when the piston reaches known positions (extreme positions or safety position), the control rod automatically reaches corresponding known positions, eliminating the need for additional sensors or detection systems.
Solution Approach 2:
The system provides inherent feedback through the mechanical guidance structure. The guide rails ensure that specific piston positions correspond to specific control rod positions, creating a deterministic relationship where the control rod's position along the predetermined path directly indicates the piston's position without requiring electronic sensors or complex measurement systems.
Data Source
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Figure 3A~3C
Figure 4A~4C
AI summary
The invention relates to a control device (30) for controlling an airflow guiding system (20), comprising: - at least one vane (21) that is rotatable on a shaft (21a) of the vane between a first angle and a second angle; - an actuator (31) comprising a body (32) inside which a piston (32a) is translatably mounted, the piston being rigidly connected to a drive rod (33); - a control rod (34) comprising a downstream end (34a) that is connected to the shaft (21a) of the vane, the actuator (31) being configured to drive the piston (32a) between a first end position (P1') and a second end position (P2') of a nominal operating range and the downstream end (34a) of the control rod (34) between a first end position (P1) and a second end position (P2) of a nominal operating range in which the vane (21) is movable between a first angle and a second angle, the device being characterised in that it comprises a drive mechanism (40) that connects an upstream end (33a) of the drive rod (33) to an upstream end (34b) of the control rod (34), which is opposite the downstream end (34a), and in that the drive mechanism (40) is configured so that, in the event of the control device failing, it places the downstream end (34a) of the control rod (34) in a safety position (PS) located between the first end position (P1) and a second end position (P2) of the nominal operating range and in which the vane (21) is oriented at a safety pitch angle between the first angle and the second angle.